Jana R. Cooke, MD

• Clinical Instructor, Division of Pulmonary and
• Critical Care Medicine, University of California
• San Diego School of Medicine, San Diego, CA
• Staff Physician, Veterans Administration San Diego
• Healthcare System, La Jolla, USA

Intracranial aneurysms can present with cranial neuropathies as a result of cranial nerve compression from mass effect within the cavernous sinus or irritation by hemodynamic effects tylenol arthritis pain label buy generic celebrex 200 mg on line. When it occurs arthritis yoga poses buy celebrex mastercard, it can cause carotid cavernous fistulas and potentially fatal epistaxis due to erosion through the sphenoid sinus juvenile arthritis in feet buy cheap celebrex 200 mg. It is important to rule out the possibility of an aneurysm prior to planning surgery for resection of a presumed tumor rheumatoid arthritis ulnar drift discount celebrex 100 mg buy. How do these clinical and radiological findings influence the decision on whether or not to intervene Surgical intervention carries a significant risk for procedural morbidity and mortality arthritis pain management drugs celebrex 100 mg generic, which exceeds 30% in some series. Recent series have demonstrated high rates of improvement in cranial neuropathies following flow diversion, although they may persist despite adequate aneurysm occlusion. What endovascular devices or techniques should be considered for treatment of this aneurysm If a flow-diverting stent is used, what medication should be prescribed prior to surgery Surgical Procedure the patient was treated with flow diversion and adjunctive coiling. She was started on dual antiplatelet therapy (aspirin 325 mg and clopidogrel 75 mg daily) 1 or 2 weeks prior to flow diversion, and blood tests to verify antiplatelet response were performed before the procedure. In cases in which stent placement is unplanned and patients are not placed on preoperative dual antiplatelet therapy, an intraprocedural bolus of abciximab (0. All patients are maintained on dual antiplatelet therapy for at least 6 months after flow diversion. Depending on the results of the initial follow-up angiogram, which is typically performed 6 months after the procedure, most patients are continued on aspirin 81 or 325 mg daily indefinitely. Following arterial access, the patient is systemically heparinized with an intravenous loading dose of 70 U/kg, which is adjusted accordingly to a target activated clotting time of >250 seconds. Three-dimensional rotational angiography is performed to obtain the working projections under high magnification. In contrast to coil embolization cases, the aneurysm itself can be ignored in obtaining the working angles for flow diversion. Instead, the appropriately working angles should delineate the proximal and distal landing zones of the flow diverter. In general, the lateral projection is used to visualize the proximal landing zone, whereas the anteroposterior projection is used to visualize the distal landing zone. The device length is chosen to allow for approximately 5 mm of stent on either side of the aneurysm neck. Longer devices are stiffer and therefore more difficult to advance through the microcatheter and to deploy. In these cases, the smaller distal device is deployed first, and then the larger proximal device is telescoped within the initial stent. The microcatheter is navigated over a micro guide wire into the proximal middle cerebral artery M1 segment. When adjunctive coiling is being performed, a microcatheter is jailed in the aneurysm dome prior to deployment of the flow diverter because the tines of the stent cannot be crossed with a coiling microcatheter. The initial deployment of the flow diverter is an unsheathing maneuver to open the distal portion of the device. Once the device is unsheathed to the midpoint of the aneurysm neck, the operator begins to push the device out of the microcatheter, which closes the stent interstices across the neck to improve its flow-diverting properties. Finally, after the device is unsheathed proximal to the aneurysm neck, the remainder of the device is deployed. Failure to recapture the delivery wire results in the operator having to navigate through the stent to obtain distal access, which carries the potential risk of stent displacement. After stent deployment, final angiograms should be performed to assess for stent apposition, intra-aneurysmal contrast stasis, parent vessel patency, and distal thrombosis. Once satisfied with the final result, the catheter system is removed, and a closure device is deployed into the femoral arterial puncture site. During preoperative planning, patients who are scheduled to undergo flow diversion should be started on dual antiplatelet therapy and assessed for adequate antiplatelet response whenever possible. Patients who are nonresponders to aspirin are switched to cilostazol 100 mg twice daily or dipyridamole 75 mg three times daily. Patients who are nonresponders to clopidogrel are switched to prasugrel 10 mg daily or ticagrelor 90 mg twice daily. The neurointerventionalist must be prepared to perform salvage tactics including intra-arterial thrombolysis, mechanical thrombectomy, or angioplasty. Adjunctive coiling during flow-diverting stent placement is considered to promote intra-aneurysmal thrombosis in aneurysms 10 mm in size. Aftercare Following treatment, the patient is monitored in the intensive care unit overnight, and with an uncomplicated postoperative course, the patient is discharged home the next day on a dual antiplatelet regimen. The femoral puncture site and pedal pulses should be monitored for post-intervention hematoma and ischemia. If the angiogram demonstrates progressive or complete aneurysm occlusion without significant in-stent stenosis, clopidogrel is discontinued, and the patient is maintained indefinitely on antiplatelet monotherapy with aspirin. These events are diagnosed on control angiography by inspecting the distal vasculature, particularly in the branch vessel traversed by the delivery wire, being attentive to alterations in stent configuration and noting intraluminal thrombus or delayed flow through the parent vessel. Other ways to identify complications include examining clinical and neurophysiological monitoring data. Neurophysiological monitoring of changes in regional cerebral blood flow during endovascular treatment has also proved useful for early recognition of locoregional cerebral ischemia. In the event of nonocclusive thrombi or platelet aggregation, additional heparin and/or antiplatelet agents can be administered in order to stabilize the intraluminal thrombus. In rare instances of large vessel occlusion, mechanical thrombectomy may be necessary. Device migration and prolapse into the aneurysm is a serious complication of flow diversion. It is best avoided by carefully sizing and accurately deploying the flow diverter. For large or giant aneurysms, multiple devices can be deployed in a telescoping fashion. In the event of device prolapse, if distal access can be attained across the stent, an additional device can be deployed to anchor the distal portion of the prolapsed stent to the distal landing zone. If this is not possible, parent vessel occlusion may be necessary, with or without surgical revascularization with a high-flow bypass, depending on the state of the collateral flow to the distal vasculature. Infrequent, but potentially devastating, complications of flow diversion include delayed aneurysm rupture and ipsilateral intracranial hemorrhage. The underlying mechanisms for both these uncommon complications are incompletely understood. An analysis of the International Retrospective Study of Pipeline Embolization Device registry, which comprised 793 patients with 906 aneurysms, reported ipsilateral intracranial hemorrhage in 20 patients (2. This is typically discovered on routine follow-up angiography, but the patient also may present with recurrent or new cranial neuropathies. Significant residual or recurrent aneurysms after flow diversion should be retreated with placement of additional flow diverter devices, usually if the aneurysm fails to obliterate in the first year after treatment. However, lesions that are completely obliterated by flow diversion have proven to be remarkably durable; few cases of aneurysm recurrence after complete occlusion by flow diversion have been reported. Thromboembolic complications can be managed with intra-arterial thrombolysis with an antiplatelet agent. Delayed aneurysm rupture after flow diversion is uncommon, and adjunctive coiling may decrease its incidence by promoting intra-aneurysm thrombosis. Careful inspection of the flow diverter for its apposition to the parent vessel wall can detect an endoleak, which can result in persistent aneurysm filling and thromboembolic complications. Recanalization can be detected on routine follow-up imaging or can result in new or recurrent neurological symptoms. However, deconstructive treatment with parent vessel occlusion carries a risk of ischemic stroke even if patients successfully pass balloon test occlusion. Management of antiplatelet therapy in patients undergoing neuroendovascular procedures. Long-term clinical and imaging followup of complex intracranial aneurysms treated by endovascular parent vessel occlusion. Resolution of cranial neuropathies following treatment of intracranial aneurysms with the Pipeline embolization device. Retreatment rates after treatment with the Pipeline embolization device alone versus Pipeline and coil embolization of cerebral aneurysms: A single-center experience. Resolution of mass effect and compression symptoms following endoluminal flow diversion for the treatment of intracranial aneurysms. Unruptured large and giant carotid artery aneurysms presenting with cranial nerve palsy: Comparison of clinical recovery after selective aneurysm coiling and therapeutic carotid artery occlusion. Neurological examination revealed orientation to person and place only, with significant dysarthria and confusion. Sensation was decreased on the left hemibody, with associated neglect of the left upper and lower extremities and a mild left hemiparesis. The most common stroke mimics include seizures, complicated migraines, neoplasms, metabolic derangements, sepsis, and syncope. Seizures, complicated migraines, and syncope can often be ruled out by the clinical history and physical examination. Patients suffering from complicated migraines will typically have a history of migraines, and the acute episode of hemiparesis will usually be accompanied by a severe headache, scintillating scotoma, and/or aura. Symptoms associated with a syncopal episode often overlap with those of a vertebrobasilar stroke, although typically without the cranial nerve findings expected with an ischemic insult to the brainstem. History and physical examination, in addition to cranial imaging, are often sufficient to distinguish between ischemic stroke and stroke-mimicking diagnoses. Seizures: Although a post-ictal paresis or plegia is often seen following a seizure, the majority of patients will present with stereotypical motor movements or paresthesias. Unfortunately, the absence of such movements does not rule out a seizure, nor does their presence confirm diagnosis. Complicated migraines: Migraines may be complicated with either hemiplegia or vertebrobasilar symptoms (ataxia, decreased consciousness, or vertigo). Patients will often have a personal or familial history of migraines, and these episodes are often accompanied by a headache and/or scintillating scotoma. Syncope: Symptoms of syncope may resemble vertebrobasilar ischemia, including loss of consciousness and vertigo. Neoplasm: Intracranial neoplastic processes may present with stroke-like symptoms, such as in the case of seizure, intratumoral hemorrhage, or apoplexy, although presentation is often subacute or progressive. For this patient, the management of symptomatic carotid stenosis is relatively straightforward, although some debate exists regarding the timing and exact nature of treatment. This improvement in morbidity and mortality was substantially greater in patients with 90­99% stenosis. As such, the American Heart Association official guidelines recommend that revascularization for symptomatic carotid artery stenosis should ideally occur within 14 days of an ischemic event. What adjunctive measures can be undertaken to detect potential ischemic complications during the procedure Patients are typically started on 325 mg of daily aspirin prior to surgery, which is continued postoperatively, although some surgeons prefer additional perioperative clopidogrel. Patients are typically placed under general anesthesia and positioned supine with the head rotated slightly away from the operative side. A shoulder roll may assist with a slight degree of extension to increase exposure. A longitudinal incision is fashioned along the anterior border of the sternocleidomastoid muscle. This is carried down through the platysma, and a plane just medial to the anterior border of the sternocleidomastoid is identified and opened further through blunt dissection. A large transverse sensory nerve may be encountered and can be sacrificed to facilitate exposure, although the surgeon should be careful not to violate the parotid fascia. The neurovascular bundle involving the carotid artery can then be easily identified and palpated. Sharp dissection can be used to open the cervical fascia, and then blunt dissection can be performed. Important structures encountered during this exposure include the common facial vein, omohyoid muscle, and hypoglossal nerve. The common facial vein, an anteriorly oriented branch of the internal jugular vein, often lies directly superficial to the carotid bifurcation and should be suture ligated and divided to facilitate exposure. The omohyoid muscle typically marks the inferior extent of the dissection and usually can be left intact. The vagus nerve and its superior laryngeal branch lie deep to the carotid and internal jugular vein, and care must be taken to avoid disruption of these structures when dissection below the carotid is needed. Damage to the superior laryngeal branch of the vagus nerve will result in significant postoperative dysphagia. Prior to further cross-clamping, mild hypertension (systolic blood pressure 160­180 mmHg) is induced by the anesthesiologist. A shunt can be placed if clamping potentiates changes in intraoperative ischemic monitoring. It is important to start the dissection below the bulk of the plaque and truncate the plaque sharply at the proximal extent of the arteriotomy. Careful inspection of the intima is required to identify any residual debris or plaque material for removal. Particular attention must be paid to the distal end to ensure that no ledge or intimal flap is present because this significantly raises the risk of dissection. If the plaque does not come to a smooth end, it can be sharply cut and tacked down with sutures, although with adequate distal exposure this is rarely required. If tack-up sutures are needed, it is often prudent to employ a patch to obviate the possibility of residual stenosis at the distal end. Alternatively, a patch may be sewn into the arteriotomy site using an autologous saphenous vein or prosthetic material.

The bilateral A3 segments are followed distally over the corpus callosum and circumferentially dissected for approximately 1 arthritis in outside of knee purchase celebrex overnight delivery. At this point arthritis medication voltaren 100 mg celebrex purchase with mastercard, electroencephalographic burst suppression is induced for neuroprotection using titrated doses of anesthetics rheumatoid arthritis new treatments order 200 mg celebrex visa. A continuous microsurgical suction is then placed deep in the interhemispheric fissure arthritis relief medication generic celebrex 200 mg line, and temporary clips are applied proximally and distally to the anastomosis site on both A3 segments arthritis in back icd 9 buy 200 mg celebrex with visa. Arteriotomies are made, which are typically three times the diameter of the vessels. Once the bypass is completed and patency confirmed, the aneurysmal segment is again inspected and then trapped using permanent clips placed proximal and distal to the aneurysm. In cases in which direct aneurysm clipping is possible, proximal temporary clip control is recommended while performing the final aneurysm dissection. Distal-only clipping after bypass typically results in spontaneous aneurysm thrombosis and can be considered in cases of large, dysplastic, fusiform aneurysms in which proximal access is not feasible through the same exposure. Following aneurysm trapping, electroencephalographic burst suppression is discontinued, and somatosensory and motor evoked potential responses are checked. Meticulous hemostasis of the operative field is achieved, and a watertight dural closure is performed followed by replacement of the bone flap using cranial plates. Careful preoperative approach trajectory planning and vascular anatomy analysis are crucial for surgical success in the narrow and deep surgical corridor of the interhemispheric fissure, especially if a ruptured aneurysm is associated with a large hematoma and extensive cerebral swelling. Care should be taken to avoid bridging vein injury during dural opening and entry into the interhemispheric fissure. Extensive retractor use should be avoided to prevent ischemic complications and intraoperative aneurysm rupture. A proper use of bipolar forceps, suction, microscissors, and cottonoids can be aided with gentle cotton roll placement at the opposite ends of the working segment of interhemispheric fissure. When significant compromise or complete occlusion of the parent artery is unavoidable while securing the aneurysm, revascularization of distal arterial segments is necessary. Although technically challenging, an A3­A3 anastomosis is a convenient option that avoids the limitations of an extracranial-tointracranial end-to-side bypass. Preoperative imaging should be carefully inspected for sclerotic changes in the aneurysm and parent artery as well as the proximity of branching arteries, which can significantly complicate temporary and/or permanent clip placement. Alternative strategies such as distal-only clipping or trapping of the aneurysm with distal revascularization can then be considered and planned accordingly. Intraoperative somatosensory, motor evoked potential, and electroencephalogram monitoring should be used, and responses should be checked at multiple points throughout the procedure, especially if a revascularization is planned. Vasospasm monitoring includes serial neurological exams, careful monitoring of serum sodium levels, and daily transcranial Doppler ultrasonography. Standard prophylactic antibiotics such as cefazolin are continued for 24 hours postoperatively. Therapeutic antiepileptic medication levels may be maintained for up to 2 or 3 months postoperatively. Retraction injury and damage to bridging veins may result in postoperative cortical venous infarcts. Retraction or other ischemic insult to the cingulate gyri can cause postoperative akinetic mutism, which is typically transient. Other deficits can include bilateral leg weakness and behavioral and cognitive impairment that can be related to bilateral ischemic or mass effect injury to the supplementary motor area and limbic structures. In the case of intraoperative bypass failure, an extracranial-to-intracranial bypass from the ipsilateral superficial temporal artery stump with a radial artery graft can be considered. In cases of postoperative bypass failure, an additional extracranial-tointracranial bypass should only be considered when the patient is symptomatic with radiographic evidence of a perfusion deficit that has not yet resulted in a completed infarct. Upon suspicion of a vasospasm, the patient should be treated with vasopressors, or if necessary, a catheter angiogram can be performed to deliver intra-arterial vasodilators or to perform angioplasty. At 1-month follow-up, the patient was living independently without neurological deficit. Technical complications can be minimized with preoperative imaging and planning as well as meticulous surgical technique. Ruptured aneurysm patients should remain in the intensive care unit postoperatively for vasospasm monitoring. Serial neurological exams and transcranial Doppler ultrasonography are useful tools for early vasospasm detection. Hypertensive therapy is the first-line treatment, whereas intraarterial vasodilators and angioplasty are secondary means in resistant or severe vasospasm cases. A lower mortality risk than that of ruptured aneurysms in other locations has also been shown. Independent risk factors associated with unfavorable outcomes are advanced age, poor Hunt and Hess grade, rehemorrhage before treatment, intracerebral hemorrhage, intraventricular hemorrhage, and severe preoperative hydrocephalus. Microsurgical management is still a treatment option for these aneurysms, although individual treatment should be evaluated on a case-by-case basis, ideally within a multidisciplinary team. The rapid advancement of endovascular access and treatment devices will likely impact the management of these lesions in the near future. Surgical revascularization for the treatment of complex anterior cerebral artery aneurysms: Experience and illustrative review. Microneurosurgical management of aneurysms at A3 segment of anterior cerebral artery. Distal anterior cerebral artery aneurysms: Treatment and outcome analysis of 501 patients. Anatomic features of distal anterior cerebral artery aneurysms: A detailed angiographic analysis of 101 patients. Abla Case Presentation 12 A 47-year-old female presented to the neurosurgery clinic complaining of headaches. After a detailed discussion of the natural history of this aneurysm, she was advised to stop smoking and to follow the aneurysm with serial imaging. However, she continued to have headaches and returned to the clinic 4 months later. What is the appropriate interval follow-up and preferred image modality to follow incidental unruptured aneurysms When should treatment be considered for incidental unruptured aneurysms of the basilar apex What treatment modalities are available and how is the optimal treatment strategy determined Evaluation of noncontrast studies also provides additional information regarding partial thrombosis of the aneurysm and/or calcification of parent arteries that may influence treatment decisions. Inset, higher magnification view of aneurysm in coronal plane; arrows, basilar tip aneurysm; asterisk, dorsum sellae. Note that when selecting the surgical approach, it is important to appreciate the relative position of the aneurysm with the dorsum sellae. The decision to treat or observe an unruptured aneurysm must balance the risks of rupture or neurologic deficit with the potential morbidity of treatment. To estimate risks of rupture, a detailed patient history and careful review of aneurysm size, location, and morphology are required. These statistics reflected pooled data of aneurysms from multiple sites in the posterior circulation, and aneurysms of the basilar tip are associated with greater odds of rupture. A detailed history and careful review of angiographic anatomy are necessary in the evaluation of any intracranial aneurysm. Interval aneurysm growth >2 mm or development of daughter blebs suggests aneurysm instability and favors intervention. The following aneurysm morphological parameters should be considered to facilitate treatment decisions: a. Dome-to-neck ratio-the ratio between the maximum width of the dome divided by the width of the aneurysm neck c. Aspect ratio-the ratio of the maximum height of the aneurysm divided by the width of the aneurysm neck d. Other qualitative considerations-fusiform morphology, partial thrombosis, calcification of the aneurysm or parent vessels, and perforators or aberrant branches arising from the aneurysm dome Questions 1. What factors are associated with increased risk of rupture for incidentally discovered aneurysms What attributes on surveillance imaging should prompt reconsideration of intervention Decision-Making Once a decision is made to treat the aneurysm, careful consideration of both patient demographics and aneurysm morphology is needed to select the appropriate treatment modality. For posterior circulation aneurysms, such as those arising from the basilar tip, the benefits of coiling may be even more apparent. For example, in the Barrow Ruptured Aneurysm Trial, patients with posterior circulation aneurysms, but not anterior circulation aneurysms, treated with endovascular coiling continued to have superior clinical outcomes at 6-year follow-up. As a result, many centers now favor endovascular treatment modalities over microsurgery, although with careful patient selection, endovascular and open microsurgical treatment may have equivalent outcomes. The most common endovascular treatment option involves deployment of detachable coils to induce aneurysm thrombosis. With ruptured aneurysms, balloon-assisted coiling is favored because stent placement requires dual antiplatelet therapy-most commonly aspirin and clopidogrel-to maintain stent patency. In patients with unruptured aneurysms and no contraindications to dual antiplatelet therapy, stent-assisted coiling with one or more stents is often preferred and is associated with lower rates of aneurysm recanalization and need for retreatment. Even with complete aneurysm obliteration, endovascular coiling is still more likely to result in residual aneurysm or aneurysm recurrence requiring re-treatment, and aneurysms in the basilar tip are at higher risk for recanalization compared to other aneurysm locations. With long-term follow-up, large case series have shown that 26% of coiled basilar tip aneurysms require re-treatment. Rates of re-treatment are highest within the first year of treatment, but recanalization may occur in delayed fashion and annual rates of re-treatment are roughly 2. Despite the shift toward endovascular treatment of basilar artery aneurysms, microsurgical clipping remains a safe and durable treatment option for appropriately selected basilar tip aneurysms. Aneurysms with wide or complex neck configurations, smaller dome-to-neck ratios, and smaller aspect ratios (the ratio of the height of the aneurysm to the width of the neck) are less favorable for endovascular intervention and may favor clip ligation. Similarly, aneurysms that are large or giant, partially thrombosed, or with aberrant branches arising from the aneurysm dome may be better treated with open microsurgery. Although small, risks with endovascular intervention accumulate with each treatment and surveillance angiogram, and studies have consistently demonstrated greater durability with clip ligation. What aneurysm morphologic parameters favor use of either balloon-assisted or stent-assisted coiling with endovascular treatment What anatomic factors help guide approach selection when microsurgically treating aneurysms of the basilar apex Surgical Procedure Open microsurgical clipping of basilar tip aneurysms is performed under general anesthesia with adequate intravenous access to facilitate rapid transfusion in the event of an intraoperative rupture. To ensure patient safety, the procedure should be performed with neuromonitoring, including both motor evoked potentials and somatosensory evoked potentials, and a coordinated effort between the neurophysiologist and the anesthesiologist is required to place the patient in burst suppression prior to aneurysm manipulation to minimize the deleterious consequences of any potential ischemic event. For the majority of basilar tip aneurysms, which are at or near the level of the dorsum sellae (such as in the current case), and for high-riding (above the dorsum sellae) aneurysms, an orbitozygomatic trans-sylvian approach is preferred (unless the aneurysm is completely in the third ventricle). For low-riding (below the dorsum sellae) aneurysms, the subtemporal approach is preferred. The head is affixed to a Mayfield head holder and then rotated 15­20 degrees toward the contralateral shoulder and extended roughly 20 degrees to make the malar eminence the highest point in the operative field. A curvilinear incision is made behind the hairline from the root of the zygoma to approximately the midline. The scalp is elevated using an interfascial technique to protect the frontalis branch of the fascial nerve, and both the scalp and the temporalis are reflected forward. Next, the orbitozygomatic unit is released as a second piece with a reciprocating saw. This is accomplished with a stereotypical series of cuts: (1) the zygomatic root, (2) the zygomatic body, (3) from the inferior orbital fissure to cut 2, (4) the medial orbital roof, (5) the posterior orbital roof, and (6) the lateral orbital wall. Once released, the lesser wing of the sphenoid is carefully shaved down to the superior orbital fissure, and the dura is opened. The temporal lobe is then further released through careful dissection and division of arachnoid adhesions and bridging veins along the middle fossa floor and the anterior temporal pole. Further dissection of the carotid and crural cisterns frees the temporal lobe and allows it to be retracted in a posterolateral dissection. Three operative corridors to the basilar apex are then identified: (1) the supracarotid triangle, (2) the optic­carotid triangle, and (3) the carotid­oculomotor triangle. A series of anatomic steps are utilized to safely gain both proximal and distal control when accessing the basilar apex. Once the basilar apex is visualized, access to the basilar trunk must be established for proximal vascular control. For a low-lying basilar apex, a posterior clinoidectomy or transcavernous exposure may be necessary. Adenosine cardiac arrest can also be used in conjunction with proximal control of the basilar trunk or as a standalone method for a short period of aneurysm deflation. After obtaining proximal and distal control, care and time must be spent to dissect free perforating arteries to prepare the neck of the aneurysm for clip application. Utilization of temporary clipping and/or intraoperative use of adenosine may soften the aneurysm dome to facilitate mobilization of the aneurysm and circumferential dissection of perforating arteries. The optimal clip configuration depends on the aneurysm morphology, with emphasis on perforator and parent artery preservation, and it may require the use of fenestrated clips and/or multiple stacked clip configurations. Clip positioning should be immediately confirmed with intraoperative indocyanine green angiography. If doubts persist regarding aneurysm occlusion, an intraoperative angiogram may be warranted to confirm complete occlusion. This provides better visualization of the aneurysm and facilitates circumferential dissection of thalamo-perforating arteries.

Forced vital capacity the maximum volume of gas that can be forcibly and rapidly exhaled after a full inspiration arthritis zehengrundgelenk celebrex 200 mg buy visa. Frank-Starling curve a graphic illustration that shows the relationship between the degree of myocardial stretch and cardiac output arthritis after back fusion cheap celebrex 200 mg on line. A friction rub auscultated over the pericardial area is suggestive of pericarditis; a rub over the pleural area may be a sign of lung disease arthritis medication cats quality 100 mg celebrex. Frontal process of the maxilla (nasal process) a strong plate that projects upward zoom for arthritis in dogs cheap celebrex 100 mg otc, medially ward arthritis pain relief machine buy celebrex 100 mg lowest price, and backward by the side of the nose, forming part of its lateral boundary. F Fascia the fibrous connective membrane of the body that may be separated from other specifically organized structures, such as the tendons, the aponeuroses, and the ligaments, and that covers, supports, and separates muscles. Fibrin whitish, filamentous protein formed by the action of thrombin on fibrinogen. Greater alar cartilage (lower lateral cartilage) a thin, flexible plate, situated immediately below the lateral nasal cartilage and bent upon itself in such a manner as to form the medial wall and lateral wall of the nostril of its own side. Generation the process of forming a new organism or part of an organism in the airways; a sequential, numbered branch off the trachea. Glomerulus a tuft or cluster; a structure composed of blood vessels or nerve fibers, such as a renal glomerulus. Glottis the glottis is defined as the combination of the vocal folds (vocal cords) and the space in between the folds (the rima glottidis). Glycoprotein any of a class of conjugated proteins consisting of a compound of a protein with a carbohydrate group. Goblet cell one of many specialized epithelial cells that secrete mucus and form glands of the epithelium of the stomach, the intestine, and parts of the respiratory tract. Granulocyte a type of leukocyte characterized by the presence of cytoplasmic granules. Gravity the universal effect of the attraction between any body of matter and any planetary body. The force of the attraction depends on the relative masses of the bodies and on the inverse of the square of the distance between them. Haldane effect the phenomenon in which deoxygenated blood enhances the loading of carbon dioxide and the oxygenation of blood enhances the unloading of carbon dioxide during carbon dioxide transport. Heart the muscular cone-shaped hollow organ, about the size of a clenched fist, that pumps blood throughout the body and beats normally about 70 times per minute by coordinated nerve impulses and muscular contractions. Enclosed in pericardium, it rests on the diaphragm between the lower borders of the lungs, occupying the middle of the mediastinum. It is covered ventrally by the sternum and the adjoining parts of the third to the sixth costal cartilages. The weight of the heart in men averages between 280 and 340 g and in women, between 230 and 280 g. The layers of the heart, starting from the outside, are the epicardium, the myocardium, and the endocardium. The chambers include two ventricles with thick muscular walls, making up the bulk of the organ, and two atria with thin muscular walls. A septum separates the ventricles and extends between the atria (interatrial septum), dividing the heart into the right and the left sides. The left side of the heart pumps oxygenated blood into the aorta and on to all parts of the body. The right side receives deoxygenated blood from the vena cava and Glossary 599 pumps it into the pulmonary arteries. The valves of the heart include the tricuspid valve, the bicuspid (mitral) valve, the semilunar aortic valve, and the semilunar pulmonary valve. The sinoatrial node in the right atrium of the heart (under the control of the medulla oblongata in the brainstem) initiates the cardiac impulse, causing the atria to contract. Both atria contract simultaneously, followed quickly by the simultaneous contraction of the ventricles. Other factors affecting the heartbeat are emotion, exercise, hormones, temperature, pain, and stress. Hematocrit volume of erythrocytes packed by centrifugation in a given volume of blood; is expressed as the percentage of total blood volume that consists of erythrocytes. Hemodynamics the study of the physical aspects of blood circulation, including cardiac function and peripheral vascular physiologic characteristics. Hemoglobin a complex protein-iron compound in the blood that carries oxygen to the cells from the lungs and carbon dioxide away from the cells to the lungs. Heparin a polysaccharide produced by the mast cells of the liver and by basophil leukocytes that inhibits coagulation by preventing conversion of prothrombin to thrombin. It also inhibits coagulation by preventing liberation of thromboplastin from blood platelets. Histamine a substance that is normally present in the body and exerts a pharmacologic action when released from injured cells. Histotoxic hypoxia a type of hypoxia that develops in any condition that impairs the ability of tissue cells to utilize oxygen. Homeostasis a physiologic state resulting from a dynamic equilibrium maintained by monitoring processes and altered effector activity, incorporating negative feedback pathways. Hormone a substance originating in an organ or gland that is conveyed through the body to another part of the body, which it stimulates by chemical action to increased functional activity and/or increased secretion. Hydrogen ion strictly, the nucleus of a hydrogen atom separated from its accompanying electron. The hydrogen nucleus is made up of a particle carrying a unit positive electric charge, called a proton. The isolated hydrogen ion, represented by the symbol H1, is therefore customarily used to represent a proton. Hydrostatic pertaining to the pressure of liquids in equilibrium and the pressure exerted on liquids. When dissolved in water, the hydroxide ion is the strongest base that can exist in aqueous solution. The procedure is performed in specially designed chambers that permit the delivery of 100% oxygen at atmospheric pressure that is three times normal. The technique is used to overcome the natural limit of oxygen solubility in blood, which is about 0. Hyperbaric oxygenation has been used to treat carbon monoxide poisoning, air embolism, smoke inhalation, acute cyanide poisoning, decompression sickness, wounds, clostridial myonecrosis, and certain cases of blood loss or anemia in which increased oxygen transport may compensate in part for hemoglobin deficiency. Factors limiting the usefulness of hyperbaric oxygenation include the hazards of fire and explosive decompression, pulmonary damage and neurologic toxicity at high atmospheric pressures, cardiovascular debility of the patient, and the need to interrupt treatments repeatedly because exposures at maximum atmospheric pressures must be limited to 90 minutes. Hyperinflation distention by air, gas, or liquid, as in the hyperinflation of the alveoli. Hyperpnea increased depth (volume) of breathing, with or without an increased frequency. Hypersecretion substance or fluid produced by cells or glands in an excessive amount or more than normal. Hypersensitivity an abnormal condition characterized by an exaggerated response of the immune system to an antigen. Hyperventilation pulmonary ventilation rate greater than that metabolically necessary for gas exchange, resulting from an increased respiration rate, an increased tidal volume, or both. Hyperventilation causes an excessive intake of oxygen and elimination of carbon dioxide and may cause hyperoxygenenation. Hypocapnia and respiratory alkalosis then occur, leading to dizziness, faintness, numbness of the fingers and toes, possibly syncope, and psychomotor impairment. Hypoperfusion deficiency of blood coursing through the vessels of the circulatory system. Hypoventilation may be caused by an uneven distribution of inspired air (as in bronchitis), obesity, neuromuscular or skeletal disease affecting the thorax, decreased response of the respiratory center to carbon dioxide, or a reduced amount of functional lung tissue, as in atelectasis, emphysema, and pleural effusion. The results of hypoventilation are hypoxia, hypercapnia, pulmonary hypertension with cor pulmonale, and respiratory acidosis. Treatment includes weight reduction in cases of obesity, artificial respiration, and possibly tracheostomy. Symptoms of acute hypoxemia are cyanosis, restlessness, stupor, coma, Cheyne-Stokes respiration, apnea, increased blood pressure, tachycardia, and an initial increase in cardiac output that later falls, producing hypotension and ventricular fibrillation or asystole. Hypoxia inadequate oxygen tension at the cellular level, characterized by tachycardia, hypertension, peripheral vasoconstriction, dizziness, and mental confusion. I Iatrogenic pneumothorax a condition in which air or gas is present in the pleural cavity as a result of mechanical ventilation, tracheostomy tube placement, or other therapeutic intervention. Immunoglobulin one of a family of closely related but not identical proteins that are capable of acting as antibodies. Immunologic mechanism reaction of the body to substances that are foreign or are interpreted by the body as foreign. Inflammation may be acute or chronic; its cardinal signs are redness, heat, swelling, and pain, often accompanied by loss of function. The process begins with a transitory vasoconstriction, then is followed by a brief increase in vascular permeability. The second stage is prolonged and consists of sustained increase in vascular permeability, exudation of fluids from the vessels, clustering of leukocytes along the vessels walls, phagocytosis of microorganisms, deposition of fibrin in the vessel, disposal of the accumulated debris by macrophages, and finally migration of fibroblast to the area and development of new, normal cells. The severity, timing, and local character of any particular inflammatory response depend on the cause, the area affected, and the condition of the host. Inguinal ligament a fibrous band formed by the inferior border of the aponeurosis of the external oblique that extends from the anterior superior iliac spine to the pubic tubercle. Innervation the distribution or supply of nerve fibers or nerve impulses to a body part. Inotrope the most commonly used term used for various drugs that affect the strength of contraction of the heart muscle (myocardial contractility). Insomnia chronic inability to sleep or to remain asleep throughout the night; wakefulness; sleeplessness. Inspiratory capacity the volume of air that can be inhaled after a normal exhalation. Inspiratory stridor stridor is a high pitched wheezing sound resulting from turbulent air flow in the upper airway. Interatrial septum the partition or wall that separates the right and left atrium of the heart. Interstitial placed or lying between; pertaining to the interstices or spaces within an organ or tissue. Interventricular septum the partition or wall that separates the right and left ventricles of the heart. Intrinsic an intrinsic property is an essential or inherent property of a system or of a material itself or within. It is independent of how much of the material is present and is independent of the form the material. Intrinsic properties are dependent mainly on the chemical composition or structure of the material. Intubation passage of a tube into a body aperture; specifically, the insertion of a breathing tube through the mouth or nose or into the trachea to ensure a patent airway for the delivery of anesthetic gases and oxygen or both. Inverse opposite in order, nature, or effect; as one variable increases, the other decreases. Ion atom, group of atoms, or molecule that has acquired a net electrical charge by gaining or losing electrons. It occurs primarily as a complication of diabetes mellitus and is characterized by a fruity odor of acetone on the breath, mental confusion, dyspnea, nausea, vomiting, dehydration, weight loss, and, if untreated, coma. Kussmaul breathing abnormally deep, very rapid sighing respirations characteristic of diabetic ketoacidosis. The infection leads to swelling inside the throat, which interferes with normal breathing and produces the classical symptoms of a "barking" cough, stridor, and hoarseness. It is often treated with a single dose of oral steroids; occasionally epinephrine is used in more severe cases. Larynx the organ of voice that is part of the upper airway passage connecting the pharynx with the trachea. The larynx forms the caudal portion of the anterior wall of the pharynx and is lined with mucous membrane that is continous with that of the pahrynx and the trachea. The larynx exends vertically to the fourth, fifth, and sixth cervical vertebrae and is somewhat higher in the female and during childhood. It is composed of three single cartilages and three paired cartilages, all connected together by ligaments and moved by various muscles. The paired cartilages are the arytenoid, corniculate, and cuneiform, which support the vocal folds. Lesser alar cartilages the part of the nose that forms the lateral wall and is curved to correspond with the ala of the nose; it is oval and flattened, narrow behind, where it is connected with the frontal process of the maxilla by a tough fibrous membrane, in which are found three or four small nasal cartilages; also referred to as minor alar or accessory quadrate. Leukocyte a white blood cell, one of the formed elements of the circulating blood system. Five types of leukocytes are classified by the presence or absence of granules in the cytoplasm of the cell. Leukemia may be associated with a white blood cell count as high as 500,000 to 1 million per cubic millimeter L Lactic acid acid formed in muscles during activity by the breakdown of sugar without oxygen. It causes hoarse voice or the complete loss of the voice because of irritation to the vocal folds (vocal cords). Dysphonia is the medical term for a vocal disorder, of which laryngitis is one cause. The chronic form of disease occurs mostly in middle age and is much more common in men than women. Laryngopharynx the laryngopharynx or hypopharynx (Latin: pars laryngea pharyngis) is the caudal part of the pharynx; it is the part of the throat that connects to the esophagus. It lies inferior to the epiglottis and extends to the location where this common pathway diverges into the respiratory (larynx) and digestive (esophagus) pathways. The esophagus conducts food and fluids to the stomach; air enters the larynx anteriorly.

In extreme cases arthritis relief nz cost of celebrex, an overextended stomach may rupture and lead to a condition known as pneumoperitoneum (air in the peritoneal cavity of the abdomen) arthritis diet uk purchase genuine celebrex on-line. Hyperbaric Medicine the administration of oxygen at increased ambient pressures is now being used routinely to treat a variety of pathologic conditions arthritis gadgets generic 200 mg celebrex visa. Clinically arthritis fingers herbs generic 200 mg celebrex with mastercard, this therapy is referred to as hyperbaric medicine and is accomplished by means of a hyperbaric chamber arthritis back pain surgery order cheap celebrex on-line. Most of the therapeutic benefits of hyperbaric oxygenation are associated with the increased oxygen delivery to the tissues. Very little additional O2 can be combined with hemoglobin once this saturation level is reached. However, the quantity of dissolved O2 will continue to rise linearly as the PaO increases. The breath-hold diver uses the oropharyngeal musculature to pump boluses of air into the lungs to increase the volume above his or her normal total lung capacity. Although the experienced breath-hold diver can increase their lung volumes by up to 3 L, this maneuver is associated with hypotension, decreased cardiac output, pulmonary barotrauma, and pneumomediastinum. Hyperbaric oxygen has long been useful in the treatment of diseases such as decompression sickness and gas embolism. Regardless of the cause of the bubbles, hyperbaric oxygen is effective in reducing bubble size, accelerating bubble resolution, and maintaining tissue oxygenation. Hyperbaric oxygen is used empirically to enhance wound healing in conditions associated with ischemic hypoxia. Clinically, such conditions include radiation necrosis of bone or soft tissue, diabetic microangiopathy, compromised skin grafts, crush wounds, acute traumatic ischemias, and thermal burns. For these conditions, it appears that hyperbaric oxygen increases both the tissue oxygenation and capillary density. Clinical evidence supports the use of hyperbaric oxygen for the treatment of anaerobic infections, including clostridial myonecrosis (gas gangrene); a variety of necrotizing soft-tissue infections; and chronic refractory osteomyelitis. Hyperbaric oxygen added to surgery and antibiotics in the treatment of clostridial myonecrosis increases tissue salvage and decreases mortality. Carbon monoxide poisoning, which is caused by all sources of combustion (such as defective indoor heaters, automobile exhaust systems, or smoke inhalation), is the leading cause of death by poisoning in the United States. The severity of intoxication is a function of both the level and duration of carbon monoxide exposure. Hyperbaric oxygen therapy is generally a safe procedure, and complications are rare. Potential risks include temporary myopia (nearsightedness), middle ear injuries. Chapter Summary High-pressure environments have a profound effect on the cardiopulmonary system. Currently, the administration of hyperbaric oxygen is being used routinely to treat a variety of pathologic conditions, including gas diseases. Clinical connections associated with these topics include the world record for breath-holding and glossopharyngeal insufflation. Absolute shunt the sum of the anatomic and capillary shunts is referred to as true or absolute shunt. Acetylcholine plays an important role in the transmission of parasympathetic nerve impulses at the synapses. Acid a compound that yields hydrogen ions when dissociated in aqueous solution (Arrhenius definition) or acts as a hydrogen ion donor (Brønsted definition) or acts as an electron pair acceptor (Lewis definition). Acids turn blue litmus red, have a sour taste, and react with bases to form salts. The hydrogen ion concentration of the blood increases as reflected by a lowering of serum pH values. Treatment depends on diagnosis of the underlying abnormality and concurrent correction of the acid­ base imbalance. A subdivision of the lung consisting of the tissue distal to a terminal bronchiole. Acromion process lateral portion of the spine of the scapula that forms the point of the shoulder. It articulates with the clavicle and gives attachment to the deltoid and trapezius muscles. Action potential an electrical impulse consisting of a self-propagating series of polarizations and depolarizations, transmitted across the plasma membranes of a nerve fiber during the transmission of a nerve impulse and across the plasma membranes of a muscle cell during contraction or other activity. In the absence of an impulse, the inside is electrically negative and the outside is positive (the resting potential). During the passage of an impulse at any point on the nerve fiber, the inside becomes positive and the outside, negative. Acute beginning abruptly with marked intensity or sharpness, then subsiding after a relatively short period. Acute alveolar hyperventilation a condition marked by low levels of carbon dioxide, and a high pH in the blood, due to breathing excessively. Acute epiglottitis a severe, rapidly progressing bacterial infection of the upper respiratory tract that occurs in young children, primarily between 2 and 7 years of age. It is characterized by sore throat, croupy stridor, and inflamed epiglottis, which may cause sudden respiratory obstruction and possibly death. The infection is generally caused by Haemophilus influenzae, type B, although streptococci may occasionally be the causative agent. Transmission occurs by infection with airborne particles or contact with infected secretions. A lateral X-ray film of the neck shows an enlarged epiglottis and distention of the hypopharynx, which distinguishes the condition from croup. Direct visualization of the inflamed, cherry-red epiglottis by depression of the tongue or indirect laryngoscopy is also diagnostic but may produce total acute obstruction and should be attempted only by trained 585 586 Glossary personnel with equipment to establish an airway or to provide respiratory resuscitation, if necessary. Acute respiratory distress syndrome a severe pulmonary congestion characterized by diffuse injury to alveolar-capillary membranes. Fulminating sepsis, especially when gram-negative bacteria are involved, is the most common cause. Other causes include diabetic ketoacidosis, fungal infections, high altitude, pancreatitis, tuberculosis, and uremia. Also called adult respiratory distress syndrome, congestive atelectasis, hemorrhagic lung, noncardiogenic pulmonary edema, pump lung, shock lung, stiff lung, wet lung. Adenoid one of two masses of lymphatic tissue situated on the posterior wall of the nasopharynx behind the posterior nares. During childhood these masses often swell and block the passage of air from the nasal cavity into the pharynx, preventing the child from breathing through the nose. Adrenergic nerve fibers that, when stimulated, release epinephrine at their endings. Adrenergic fibers include nearly all sympathetic postganglionic fibers except those innervating sweat glands. Adrenergic receptors a site in a sympathetic effector cell that reacts to adrenergic stimulation. Two types of adrenergic receptors are recognized: alphaadrenergic, which act in response to sympathomimetic stimuli, and beta-adrenergic, which block sympathomimetic activity. In general, stimulation of alpha receptors is excitatory of the function of the host organ or tissue, and stimulation of the beta receptors is inhibitory. Afferent nerves nerves that carry impulses from the periphery to the central nervous system. Affinity attraction between two substances that, when united, form new substances. Agranulocyte any leukocyte that does not contain predominant cytoplasmic granules, such as a monocyte or lymphocyte. Airway resistance a measure of the impedance to airflow through the bronchopulmonary system. Calculated by the pressure difference between the mouth and alveoli divided by flow rate. Alar cartilage refers to the greater alar cartilage (lower lateral cartilage), which is a thin, flexible plate, situated immediately below the lateral nasal cartilage and bent upon itself in such a manner as to form the medial wall and lateral wall of the naris of its own side. Alkalosis an abnormal condition of body fluids, characterized by a tendency toward a blood pH level greater than 7. Respiratory alkalosis may be caused by hyperventilation, resulting from an excess loss of carbon dioxide and a carbonic acid deficit. Metabolic alkalosis may result from an excess intake or retention of bicarbonate, loss of gastric acid in vomiting, potassium depletion, or any stimulus that increases the rate of sodium-hydrogen exchange. When a buffer system, such as carbon dioxide retention or bicarbonate excretion, prevents a shift in pH, it is labeled compensating alkalosis. Treatment of uncompensated alkalosis involves correction of dehydration and various ionic deficits to restore the normal acid-base balance in which the ratio of carbonic acid to bicarbonate is 20:1. Allergy a hypersensitive reaction to common, often intrinsically harmless substances, most of which are environmental. Glossary 587 Alpha receptor any of the postulated adrenergic components of receptor tissues that respond to norepinephrine and to various blocking agents. The activation of the alpha receptors causes such physiologic responses as increased peripheral vascular resistance, dilation of the pupils, and contraction of pilomotor muscles. Alveolus a small outpouching of walls of alveolar space through which gas exchange between alveolar air and pulmonary capillary blood takes place. Amniocentesis an obstetric procedure in which a small amount of amniotic fluid is removed for laboratory analysis. It is usually performed between the sixteenth and twentieth weeks of gestation to aid in the diagnosis of fetal abnormalities, especially genetic disorders. Amniotic fluid liquid produced by the fetal membranes and the fetus; it surrounds the fetus throughout pregnancy, usually totaling about 1000 mL at term. Anaerobic threshold the point at which the level of exercise is greater than the ability of the cardiopulmonary system to provide a sufficient supply of oxygen to the muscles, causing anaerobic metabolism to ensue. Anastomosis joining of vessels, either naturally or surgically, to allow flow to other structures. Anatomic shunt an anatomic shunt (also called a true shunt) exists when blood flows from the right side of the heart to the left side without coming in contact with an alveolus for gas exchange. In the healthy lung, there is a normal anatomic shunt of about 3 percent of the cardiac output. Common abnormalities that cause anatomic shunting include congenital heart disease, intrapulmonary fistula, and vascular lung tumors. Anemia disorder characterized by a decrease in hemoglobin in the blood to levels below the normal range. Anemic hypoxia a type of hypoxia in which the oxygen tension in the arterial blood is normal, but the oxygen-carrying capacity of the blood is inadequate. This form of hypoxia may develop from (1) a low amount of hemoglobin in the blood or (2) a deficiency in the ability of hemoglobin to carry oxygen, such as carbon monoxide poisoning. This test is most commonly performed in patients who present with altered mental status, unknown exposures, acute renal failure, and acute illnesses. Anoxia an abnormal condition characterized by a local or systemic lack of oxygen in body tissues. It may result from an inadequate supply of oxygen to the respiratory system, an inability of the blood to carry oxygen to the tissues, or a failure of the tissues to absorb the oxygen from the blood. Anterior indicating the front of a structure or body surface relative to other body parts. Antibody protein substance that develops in response to and interacts with an antigen. Antigen substance that induces the formation of antibodies that interact specifically with it. Aorta the main trunk of the systemic arterial circulation, comprising four parts: the ascending aorta, the arch of the aorta, the thoracic portion of the descending aorta, and the abdominal portion of the descending aorta. The arch rises at the level of the border of the second sternocostal articulation of the right side, passes to the left in front of the trachea, bends dorsally, and becomes the descending aorta. Apneustic center a portion of the pontine respiratory centers that influences the respiratory components of the medulla. If unrestrained, the apneustic center continually sends neural impulses to the ventral respiratory group and dorsal respiratory group in the medulla. Arterial-venous oxygen content difference the differrence between the oxygen content of arterial blood (CaO) and the oxygen content of venous 2 blood (CvO). Asphyxia severe hypoxia leading to hypoxemia and hypercapnia, loss of consciousness, and, if not corrected, death. Some of the more common causes of asphyxia are drowning, electrical shock, aspiration of vomitus, lodging of a foreign body in the respiratory tract, inhalation of toxic gas or smoke, and poisoning. Oxygen and artificial ventilation are promptly administered to prevent damage to the brain. Aspiration pneumonia an inflammatory condition of the lungs and bronchi caused by the inhalation of foreign material or acidic vomitus. Asthma a respiratory disorder characterized by recurring episodes of paroxysmal dyspnea, wheezing on expiration and/or inspiration caused by constriction of the bronchi, coughing, and viscous mucoid bronchial secretions. The episodes may be precipitated by inhalation of allergens or pollutants, infection, cold air, vigorous exercise, or emotional stress. Treatment may include elimination of the causative agent, hyposensitization, aerosol or oral bronchodilators, beta-adrenergic drugs, methylxanthines, cromolyn, leukotriene inhibitors, and short- or long-term use of corticosteroids. Ataxia an abnormal condition characterized by impaired ability to coordinate movement. Atelectasis an abnormal condition characterized by the collapse of alveoli, preventing the respiratory exchange of carbon dioxide and oxygen in a part of the lungs.

Also arthritis in back pictures celebrex 200 mg buy free shipping, avoidance of strenuous physical activity to reduce excessive mechanical stress arthritis relief bracelet reviews celebrex 100 mg buy mastercard, which may accelerate disease progression can arthritis pain make you tired purchase discount celebrex, is recommended in all patients with inherited dilated cardiomyopathies arthritis knee injections buy cheap celebrex on line. Also during follow-up rheumatoid arthritis medication effects celebrex 100 mg order, R-wave amplitude should be closely monitored because of the progressiveness of the disease. The disease is highly prevalent in children and is characterized by increasing ventricular ectopy during exercise tests. Typically, ventricular ectopy (initially often monomorphic) appears when heart rate exceeds 90 to 100 bpm. Exercise tests are generally very reproducible (and can be used to guide therapy). The genetic basis centers on genes involved in the calcium homeostasis of cardiac cells. Patients who first presented with an out-of-hospital cardiac arrest are at high risk for repeated events, and the same holds for patients who present early in life. Nadolol, being a long-acting drug, has been demonstrated to be clinically effective and is therefore preferred for prophylactic therapy. Exercise testing can be of value to titrate the dosage of -blockers and should be repeated periodically to ensure that the degree of sinus tachycardia that precedes the onset of ventricular arrhythmias is never reached. Several case reports have been described showing that both appropriate and inappropriate shocks can trigger catecholamine release, subsequently resulting in multiple shocks, arrhythmic storm and death. Long to very long time to therapy (>30 seconds) is recommended to allow for spontaneous termination of nonsustained ventricular arrhythmias (see Table 21-1). Elliott P, Andersson B, Arbustini E, et al: Classification of the cardiomyopathies: a position statement from the European Society of Cardiology Working Group on Myocardial and Pericardial Diseases. Developed in collaboration with the American Association for Thoracic Surgery, American Society of Echocardiography, American Society of Nuclear Cardiology, Heart Failure Society of America, Heart Rhythm Society, Society for Cardiovascular Angiography and Interventions, and Society of Thoracic Surgeons. Sen-Chowdhry S, Syrris P, Ward D, et al: Clinical and genetic characterization of families with arrhythmogenic right ventricular dysplasia/cardiomyopathy provides novel insights into patterns of disease expression. Taylor M, Graw S, Sinagra G, et al: Genetic variation in titin in arrhythmogenic right ventricular cardiomyopathy-overlap syndromes. Rigato I, Bauce B, Rampazzo A, et al: Compound and digenic heterozygosity predicts lifetime arrhythmic outcome and sudden cardiac death in desmosomal gene-related arrhythmogenic right ventricular cardiomyopathy. Wichter T, Borggrefe M, Haverkamp W, et al: Efficacy of antiarrhythmic drugs in patients with arrhythmogenic right ventricular disease. Dalal D, Jain R, Tandri H, et al: Long-term efficacy of catheter ablation of ventricular tachycardia in patients with arrhythmogenic right ventricular dysplasia/cardiomyopathy. Watanabe H, Chinushi M, Izumi D, et al: Decrease in amplitude of intracardiac ventricular electrogram and inappropriate therapy in patients with an implantable cardioverter defibrillator. Mugnai G, Tomei R, Dugo C, et al: Implantable cardioverterdefibrillators in patients with arrhythmogenic right ventricular cardiomyopathy: the course of electronic parameters, clinical features, and complications during long-term follow-up. Bramanti O, Melluso C, Luca F, et al: Late sensing due to extremely delayed right ventricular activation in arrhythmogenic right ventricular cardiomyopathy. Lochy S, Francois B, Hollanders G, et al: Left ventricular sensing and pacing for sensing difficulties in internal cardioverter defibrillator therapy for arrhythmogenic right ventricular cardiomyopathy. Antzelevitch C, Brugada P, Borggrefe M, et al: Brugada syndrome: report of the second consensus conference: endorsed by the Heart Rhythm Society and the European Heart Rhythm Association. Papavassiliu T, Veltmann C, Doesch C, et al: Spontaneous type 1 electrocardiographic pattern is associated with cardiovascular magnetic resonance imaging changes in Brugada syndrome. Nademanee K, Veerakul G, Chandanamattha P, et al: Prevention of ventricular fibrillation episodes in Brugada syndrome by catheter ablation over the anterior right ventricular outflow tract epicardium. Sacher F, Probst V, Iesaka Y, et al: Outcome after implantation of a cardioverter-defibrillator in patients with Brugada syndrome: a multicenter study. Watanabe H, Chinushi M, Sugiura H, et al: Unsuccessful internal defibrillation in Brugada syndrome: focus on refractoriness and ventricular fibrillation cycle length. Collaborative Research Group of the European Human and Capital Mobility Project on Familial Dilated Cardiomyopathy. Hayashi M, Denjoy I, Extramiana F, et al: Incidence and risk factors of arrhythmic events in catecholaminergic polymorphic ventricular tachycardia. Leenhardt A, Denjoy I, Guicheney P: Catecholaminergic polymorphic ventricular tachycardia. Biophysically detailed cardiac simulations can explain experimental observations and help reveal how organ-scale arrhythmogenic phenomena (ectopic heartbeats, conduction failure, electrical turbulence, etc. This extensive "virtual heart" methodology1-6 has been built upon a strong foundation of experimentally constrained model developments. Advancements in single cell action potential modeling have produced the contemporary building blocks for constructing models of the atria7-10 and the ventricles11-14 with unprecedented levels of biophysical detail and accuracy. Similarly, cell mechanics (myofilament) models (reviewed by Trayanova and Rice15) have enabled the assembly of coupled electromechanical models of the heart. Such developments have helped to fuel the exciting progress made in simulating cardiac electrical16-23 and mechanical20,24,25 behavior at the organ level. Importantly, the emergent, integrative behaviors in the heart uncovered by these modeling studies have demonstrated how they result from complex interactions not only within a specific level but also from feedforward and feedback interactions that connect a broad range of hierarchical levels of biological organization, further underscoring the importance of integrative research in heart (dys)function. Several recent reviews have been written on our current understanding of atrial and ventricular mechanisms from an integrative interactions perspective,6,26-36 often derived from computer simulations. Recent developments in modeling of heart rhythm and pump disorders have begun to adopt the patient-specific approach,5 where the geometry and structure of the heart (including structural remodeling such as infarction37 or fibrosis38), and in some cases the torso geometry,39,40 is reconstructed from clinical imaging modalities. Patientspecific electrophysiologic or mechanical information has also begun to be incorporated in simulation studies. In this article, we review the current state-of-the-art in using computer modeling as applied to patients with devices. We present the basic principles of how such models are developed, along with how simulations of arrhythmias and pump dysfunction as well as patient heart-device interactions can be used to improve treatment of patients with heart disease. This section reviews briefly the methodologic basis and advancements in biophysically based models of heart function. Modeling the electrophysiology of the heart, even in its most simple mathematical representation, involves propagation of an electrical impulse (cell action potential) in a three-dimensional network of cells. In the vast majority, these models involve biophysically detailed cell membrane kinetics, that is, ionic currents, pumps, and exchangers, the mathematical description of which is based on the formalism introduced by Hodgkin and Huxley. In tissue, atrial myocytes are electrically connected via low-resistance gap junctions. Ionic current can flow from cell to cell via this pathway, in addition to the current exchange between intracellular and extracellular spaces through cell membrane proteins. Propagation of the action potential is typically modeled using spatially continuous models that are viewed as resulting from a local spatial homogenization of behavior in tissue compartments (membrane, intracellular and extracellular spaces). The conductivity tensor fields used in these continuous models integrate all the information about the distribution of gap junctions over the cell membranes as well as the fiber, sheet, and other microstructure organization in the atria. Cardiac tissue has orthotropic passive electrical conductivities that arise from the cellular organization of the myocardium into fibers and laminar sheets. Global conductivity values in the atrial or ventricular model are obtained by combining fiber and sheet organization with myocyte-specific local conductivity values. Multiscale models of human heart electrophysiology are typically modular, allowing the use of a variety of cellular ionic models, with different levels of biophysical detail. Animageofthethree-dimensionalgeometricmodelof the patient heart rendered with the epicardium and the infarct border zone semitransparent is shown in the third panel. The right-most panel presents in silico activation map of arrhythmia, revealing reentry on the left ventricular endocardium. Inthisprocess,thematrix of transformation provides the "deformed" fiber orientations, which are the ones matching the patient ventricular geometry. Because the atria are much thinner than the ventricles, image-based models of at least one of the human atrial chambers can further be subclassified into surface and volumetric models. Surface models represent atrial geometry in three dimensions but neglect wall thickness50,51,57,58; the latter is not true for volumetric models. Rule-based approaches have been used to assign fiber orientation consistent with measurements, either manually or using a semiautomatic rule-based approach. Finally, numeric approaches for simulating the electrical behavior of the heart have been described in detail in previous publications, some of which offer comprehensive reviews on the subject. Specifically, modeling work has been conducted to optimize antitachycardia pacing, as reviewed in this section. This criterion is based on the critical mass hypothesis, which postulates that a defibrillation shock is successful if it produces a strong extracellular potential gradient over a large amount of ventricular tissue mass. Optimization of electrode/can placement was also performed in this torso by changing the anatomic relations of electrodes to the heart and by varying the length of the epicardial electrode. The middle graph represents the spatial extent (inred) of the best capture results obtained for eachmodel. In a patient with tricuspid valve atresia, two configurations with epicardial leads were found to have the lowest defibrillation threshold. The study also demonstrated that determining extracellular potential gradients during the shock without actually simulating defibrillation was not sufficient to predict defibrillation success or failure. Research has reported a strong correlation between increased arrhythmia risk and the presence of T-wave alternans. Currently, this trend continues to be strong, with cell-, tissue-, and organ-level studies contributing to major advances in our understanding of heart rhythm and pump dysfunction. In addition, a major thrust in computational cardiac electrophysiology had been to use models as a test bed for evaluation of antiarrhythmic drugs, including testing hypotheses regarding the mechanisms of drug action on the scale of the whole heart; the latter work has the potential to guide the drug development pipeline more effectively, a process that currently has high failure rates and high costs. The use of heart models in personalized diagnosis, treatment planning, and prevention of sudden cardiac death is also slowly becoming a reality. Computer simulations of the function of the individualized diseased heart and its response to electrophysiologic therapies such as pacing and defibrillation represent a profound example of a research avenue in the new discipline of computational medicine, and offer high promise for clinical translation. Vigmond E, Vadakkumpadan F, Gurev V, et al: Towards predictive modelling of the electrophysiology of the heart. Gurev V, Lee T, Constantino J, et al: Models of cardiac electromechanics based on individual hearts imaging data: imagebased electromechanical models of the heart. Nygren A, Fiset C, Firek L, et al: Mathematical model of an adult human atrial cell: the role of K+ currents in repolarization. Clayton R, Bishop M: Computational models of ventricular arrhythmia mechanisms: recent developments and future prospects. Hu Y, Gurev V, Constantino J, et al: Effects of mechano-electric feedback on scroll wave stability in human ventricular fibrillation. Hu Y, Gurev V, Constantino J, Trayanova N: Efficient preloading of the ventricles by a properly timed atrial contraction underlies stroke work improvement in the acute response to cardiac resynchronization therapy. Heijman J, Voigt N, Nattel S, Dobrev D: Cellular and molecular electrophysiology of atrial fibrillation initiation, maintenance, and progression. Ashikaga H, Arevalo H, Vadakkumpadan F, et al: Feasibility of image-based simulation to estimate ablation target in human ventricular arrhythmia. Prakosa A, Malamas P, Zhang S, et al: Methodology for imagebased reconstruction of ventricular geometry for patientspecific modeling of cardiac electrophysiology. Dang L, Virag N, Ihara Z, et al: Evaluation of ablation patterns using a biophysical model of atrial fibrillation. Jacquemet V, Virag N, Kappenberger L: Wavelength and vulnerability to atrial fibrillation: Insights from a computer model of human atria. Ukwatta E, Yuan J, Qiu W, et al: Myocardial infarct segmentation and reconstruction from 2D late-gadolinium enhanced magnetic resonance images. Reumann M, Bohnert J, Seemann G, et al: Preventive ablation strategies in a biophysical model of atrial fibrillation based on realistic anatomical data. Vadakkumpadan F, Arevalo H, Ceritoglu C, et al: Image-based estimation of ventricular fiber orientations for personalized modeling of cardiac electrophysiology. Uldry L, Virag N, Jacquemet V, et al: Optimizing local capture of atrial fibrillation by rapid pacing: study of the influence of tissue dynamics. Uldry L, Virag N, Lindemans F, et al: Atrial septal pacing for the termination of atrial fibrillation: study in a biophysical model of human atria. Eason J, Schmidt J, Dabasinskas A, et al: Influence of anisotropy on local and global measures of potential gradient in computer models of defibrillation. Arevalo H, Rodriguez B, Trayanova N: Arrhythmogenesis in the heart: Multiscale modeling of the effects of defibrillation shocks and the role of electrophysiological heterogeneity. Anderson C, Trayanova N, Skouibine K: Termination of spiral waves with biphasic shocks: role of virtual electrode polarization. Tilg B, Fischer G, Modre R, et al: Model-based imaging of cardiac electrical excitation in humans. Berger T, Fischer G, Pfeifer B, et al: Single-beat noninvasive imaging of cardiac electrophysiology of ventricular preexcitation. Paper presented at Computing in Cardiology (CinC), Krakow, Poland, Sep 9-12, 2012. The sixth publication, dated 1962, is entitled "Complications of an Implantable Cardiac Pacemaker. Since that initial implant, millions of pacemakers have been implanted, saving lives and reducing or even eliminating symptoms. With these undeniable benefits of electronic pacemakers have also come the complications, occurring in 5% to 10% of implant procedures. Long-term management of pacemaker patients is complicated by device and lead failures and a requirement to change out the device when the battery expires. One approach that has been widely publicized over the last few years is the idea of creating a "biological pacemaker" by either gene transfer or cell transplantation methods (Table 23-1). Their delivery method essentially scattered the transgene around the ventricular myocardium. The initial report targeted the left atrium,12 and a subsequent report showed gene transfer to the left bundle branch. The investigators did not report the time course of heart rate increase for the mice, but in the pigs they found a statistically significant increase in heart rate only on the second day postinjection. The usual experience with plasmid-mediated gene transfer is that the effect persists for several weeks or even months after gene transfer. Additional concern is raised when considering possible mechanisms for the increase in heart rate. The mouse study did not target the specialized conducting system, and under ordinary circumstances atrial myocytes should not display automaticity.

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