Jack W. Hsu, M.D.

• Assistant Professor
• Department of Medicine
• University of Florida
• Clinical Assistant Professor
• Department of Medicine
• University of Florida Shands Cancer Center
• Gainesville, Florida

Amiodarone versus lidocaine and placebo for the prevention of ventricular fibrillation after aortic crossclamping: a randomized muscle relaxant modiek purchase 500 mg robaxin visa, double-blind spasms esophagus problems order generic robaxin canada, placebocontrolled trial spasms right abdomen generic robaxin 500 mg with mastercard. Extracardiac medical and neuromuscular implications in restrictive cardiomyopathy muscle relaxant 5859 500 mg robaxin purchase visa. The restrictive and infiltrative cardiomyopathies and arrhythmogenic right ventricular dysplasia/cardiomyopathy muscle relaxant constipation buy generic robaxin 500 mg line. Paradoxical low flow and/or low gradient severe aortic stenosis despite preserved left ventricular ejection fraction: implications for diagnosis and treatment. Paradoxical low-flow, low-gradient severe aortic stenosis despite preserved ejection fraction is associated with higher afterload and reduced survival. Progress with genetic cardiomyopathies: screening, counseling, and testing in dilated, hypertrophic, and arrhythmogenic right ventricular dysplasia/ cardiomyopathy. Arrhythmogenic right ventricular cardiomyopathy/dysplasia: clinical impact of molecular genetic studies. An updated review on the clinicopathologic aspects of arrhythmogenic right ventricular cardiomyopathy. Postoperative sudden death in two adolescents with myelomeningocele and unrecognized arrhythmogenic right ventricular dysplasia. Prospective evaluation of relatives for familial arrhythmogenic right ventricular cardiomyopathy/dysplasia reveals a need to broaden diagnostic criteria. Clinical and genetic characterization of families with arrhythmogenic right ventricular dysplasia/cardiomyopathy provides novel insights into patterns of disease expression. Spectrum of clinicopathologic manifestations of arrhythmogenic right ventricular cardiomyopathy/dysplasia: a multicenter study. Arrhythmogenic right ventricular cardiomyopathy/dysplasia clinical presentation and diagnostic evaluation: results from the North American Multidisciplinary Study. Echocardiographic findings in patients meeting task force criteria for arrhythmogenic right ventricular dysplasia: new insights from the multidisciplinary study of right ventricular dysplasia. Prevalence and pathophysiologic attributes of ventricular dyssynchrony in arrhythmogenic right ventricular dysplasia/cardiomyopathy. Diagnosis of arrhythmogenic right ventricular cardiomyopathy/dysplasia: proposed modification of the Task Force Criteria. Task Force of the Working Group Myocardial and Pericardial Disease of the European Society of Cardiology and of the Scientific Council on Cardiomyopathies of the International Society and Federation of Cardiology. Unsuspected cardiac lesions associated with sudden unexpected perioperative death. Arrhythmogenic right ventricular cardiomyopathy: From genetics to diagnostic and therapeutic challenges. Three-dimensional echocardiographic reconstruction of the mitral valve, with implications for the diagnosis of mitral valve prolapse. Outcome of valve repair and the Cox maze procedure for mitral regurgitation and associated atrial fibrillation. Long-term assessment of mitral valve reconstruction with resection of the leaflets: triangular and quadrangular resection. Late outcomes of mitral valve repair for floppy valves: Implications for asymptomatic patients. Very long-term survival and durability of mitral valve repair for mitral valve prolapse. Mitral valve replacement versus repair: propensity-adjusted survival and quality-of-life analysis. Impact of timing and surgical approach on outcomes after mitral valve regurgitation operations. Arrhythmias in the mitral valve prolapse syndrome: clinical significance and management. Complex arrhythmias in mitral regurgitation with and without mitral valve prolapse: contrast to arrhythmias in mitral valve prolapse without mitral regurgitation. Malignant ventricular arrhythmias in patients with mitral valve prolapse and mild mitral regurgitation. Cerebral ischemic events after diagnosis of mitral valve prolapse: a community-based study of incidence and predictive factors. Cost-effectiveness of infective endocarditis prophylaxis for mitral valve prolapse with or without a mitral regurgitant murmur. Mitral valve prolapse: left ventricular hemodynamics in patients with chest pain, dyspnea or both. Early extubation after open-heart surgery with total intravenous anaesthetic technique. A prospective randomized study of paravertebral blockade in patients undergoing robotic mitral valve repair. Asymptomatic significant patent foramen ovale: giving patent foramen ovale management back to the cardiologist. Diagnosis of patent foramen ovale by transesophageal echocardiography and correlation with autopsy findings. Prevalence and repair of intraoperatively diagnosed patent foramen ovale and association with perioperative outcomes and long-term survival. The incidental finding of a patent foramen ovale during cardiac surgery: should it always be repaired Population-based study of the relationship between patent foramen ovale and cerebrovascular ischemic events. Patent foramen ovale closure vs medical therapy for stroke prevention: meta-analysis of randomized trials and review of heterogeneity in meta-analyses. Transcatheter closure of patent foramen ovale after presumed paradoxical embolism. Should a patent foramen ovale found incidentally during isolated coronary surgery be closed The impact of newly diagnosed patent foramen ovale in patients undergoing off-pump coronary artery bypass grafting: case series of eleven patients. Aspects of mechanical ventilation affecting interatrial shunt flow during general anesthesia. Aetiology, diagnosis and management of infective causes of severe haemoptysis in intensive care units. Swan-Ganz catheter induced pulmonary artery perforation during cardiac surgery concerning two cases. Multidisciplinary management of life-threatening massive hemoptysis: a 10-year experience. Role of fiberoptic bronchoscopy in conjunction with the use of double-lumen tubes for thoracic anesthesia: a prospective study. Therapeutic embolization of bronchial artery: a successful treatment in 209 cases of relapse hemoptysis. Pulmonary artery catheter induced pulmonary artery rupture in patients undergoing cardiac surgery. Small amounts of hemoptysis as an early warning sign of pulmonary artery rupture by a pulmonary arterial catheter. Pathophysiology of rupture of the pulmonary artery by pulmonary artery balloon-tipped catheters. Catheter-induced pulmonary artery perforation: Mechanisms, management, and modifications. The epidemiology of the postpericardiotomy syndrome: A common complication of cardiac surgery. Constrictive pericarditis in the modern era: evolving clinical spectrum and impact on outcome after pericardiectomy. Diastolic heart failure: restrictive cardiomyopathy, constrictive pericarditis, and cardiac tamponade: clinical and echocardiographic evaluation. Constrictive pericarditis in the modern era: novel criteria for diagnosis in the cardiac catheterization laboratory. Diagnostic value of mitral annular velocity for constrictive pericarditis in the absence of respiratory variation in mitral inflow velocity. Differentiation of constrictive pericarditis from restrictive cardiomyopathy using mitral annular velocity by tissue Doppler echocardiography. Tricuspid regurgitation in patients undergoing pericardiectomy for constrictive pericarditis. Surgical treatment of constrictive pericarditis: analysis of outcome diagnostic error. Impact of left ventricular function on immediate and long-term outcomes after pericardiectomy in constrictive pericarditis. Pericardiectomy for constrictive pericarditis: a clinical, echocardiographic, and hemodynamic evaluation of two surgical techniques. Pericardial effusion in patients with cancer: outcome with contemporary management stategies. Diastolic collapse of the right ventricle with cardiac tamponade: an echocardiographic study. Consecutive 1127 therapeutic echocardiographically guided pericardiocenteses: clinical profile, practice patterns, and outcomes spanning 21 years. Hemodynamic instability after cardiac surgery: transesophageal echocardiographic diagnosis of a localized pericardial tamponade. The importance of transesophageal echocardiography in diagnosis of pericardial tamponade after cardiac surgery. Penetrating intrapericardial wounds: clinical experience with a surgical protocol. Effects of dobutamine and norepinephrine on oxygen availability in tamponade-induced stagnant hypoxia: a prospective, randomized, controlled study. Surgical staging for simultaneous coronary and carotid disease: a study including prospective randomization. Modeling stroke risk after coronary artery bypass and combined coronary artery bypass and carotid endarterectomy. Combined carotid and coronary revascularization: the preferred approach to the severe vasculopath. Effect of coronary artery bypass graft surgery on survival: overview of 10-year results from randomised trials by the Coronary Artery Bypass Graft Surgery Trialists Collaboration. The influence of concurrent carotid endarterectomy on coronary bypass: a case-controlled study. Microemboli during coronary artery bypass grafting: Genesis and effect on outcome. Management strategy for simultaneous carotid endarterectomy and coronary revascularization. Screening carotid ultrasonography and risk factors for stroke in coronary artery surgery patients. Noninvasive screening for asymptomatic carotid artery disease prior to cardiac operations: experience with 500 patients. Impact of preexisting cerebral ischemia detected by magnetic resonance imaging and angiography on late outcome after coronary artery bypass surgery. Stroke risk after coronary artery bypass graft surgery and extent of cerebral artery atherosclerosis. Early and delayed stroke after coronary surgery - an analysis of risk factors and the impact on short- and long-term survival. Stroke after cardiac surgery and its association with asymptomatic carotid disease: an updated systematic review and meta-analysis. A systematic review of outcomes following staged and synchronous carotid endarterectomy and coronary artery bypass. Patients undergoing cardiac surgery with asymptomatic unilateral carotid stenoses have a low risk of peri-operative stroke. Carotid stenosis and perioperative stroke risk in symptomatic and asymptomatic patients undergoing vascular or coronary surgery. Simultaneous carotid endarterectomy and coronary artery bypass grafting: results in specific patient groups. Is there any benefit from staged carotid and coronary revascularization using carotid stents Is routine intravascular shunting necessary for carotid endarterectomy in patients with contralateral occlusion A modified combined approach to operative carotid and coronary artery disease: 82 cases in 8 years. Do shorter-acting neuromuscular blocking drugs or opioids associate with reduced intensive care unit or hospital lengths of stay after coronary artery bypass grafting Routine immediate extubation after cardiac operation: a review of our first 100 patients. Wake-up test after carotid endarterectomy for combined carotid-coronary artery surgery: a case series. Multiple coronary arteriovenous fistulas to the coronary sinus with an unruptured coronary sinus aneurysm and restrictive coronary sinus opening to the right atrium. Treatment of high-output coronary artery fistula by off-pump coronary artery bypass grafting and ligation of fistula. Congenital malformations of the coronary arteries: the Texas Heart Institute experience. Outcome of cardiovascular surgery and pregnancy: a systematic review of the period 1984-1996. Effect of mitral valve prosthetic surgery on the outcome of a growth-retarded fetus. Fetal and maternal effects of sodium nitroprusside used to counteract hypertension in gravid ewes.

In conclusion spasms tamil meaning 500 mg robaxin buy with visa, the results from these different validation studies indicate that this is a technology in evolution muscle relaxant potency buy robaxin cheap online. Pulsatility is easily assessed using parameters muscle relaxant cvs order 500 mg robaxin fast delivery, such as the area under the pressure wave muscle relaxant hiccups 500 mg robaxin order with visa, area under the systolic portion of the wave spasms on right side of stomach discount robaxin 500 mg on line, or standard deviation of the wave. Calibrated Pulse Contour Cardiac Output Deriving the calibration factor is more complex. The dose of lithium needed for calibration is minimal and has no known therapeutic side effects. The principle of this technology is based on the idea that blood volume in the arterial vascular bed varies during the cardiac cycle. The blood volume in the respective finger can be held constant using a rapid response finger pressure cuff (volume clamping). To measure thoracic electrical bioimpedance, an alternating current of low amplitude is introduced and simultaneously sensed by electrodes placed around the neck and laterally on the thorax or abdomen. Changes in thoracic bioimpedance are induced by ventilation and pulsatile blood flow, and processing of the measured signal results in a characteristic impedance (Z) waveform. Only the cardiacinduced pulsatile component of the total change in electrical impedance is analyzed time-dependent impedance change (dZ/dt) and the respiratory component is filtered out. The limitations to this technology are still significant,438 particularly in patients undergoing cardiac surgery. A Teflonpledgetted purse-string suture is placed around the catheter to provide a surface for clotting upon removal of the catheter. The catheter is brought out through the skin in the subxiphoid region and is sutured in place. The possibility of air embolism to the coronary or cerebral circulations is always present. There is also the risk of clot formation on the catheter and subsequent embolization when the catheter is flushed or removed; therefore a continuous flushing system is necessary to avoid thrombus formation on the catheter tip in the postoperative period. It therefore should be removed while the chest tubes are still in place to diagnose and treat this problem. Other reported complications include catheter retention and prosthetic valve entrapment. This procedure raises a number of issues including how deep to place the catheter and what pressures and flows to use with the administration of the cardioplegia. The ultimate sign of proper positioning is the establishment of asystole upon cardioplegia infusion. Further details of the insertion procedure can be found in articles by Lebon and colleagues448 and Clements and associates. Afterload is roughly defined as the force that impedes or opposes ventricular contraction. This has clinical significance because left ventricular wall stress is one of the major determinants of myocardial oxygen consumption (see Chapters 6 and 7). Transesophageal Echocardiography Multimedia Manual: A Perioperative Transdisciplinary Approach. The formulas, normal values, and units for the calculation of various hemodynamic parameters are presented in Tables 13. Although these parameters are easily derived using the standard formulas, many modern monitors perform these calculations. To compare data among patients of different body weights and types, the various hemodynamic parameters may be normalized by indexing them to body surface area. Frank-Starling Relationships Myocardial function depends on the contractile state and the preload of the ventricle (sarcomere length at end-diastole). The relationship between the ventricular preload and myocardial work (ventricular stroke work) is the Frank-Starling relationship. The relationship between end-diastolic pressure and volume is usually nonlinear (as described by the diastolic ventricular compliance curve) and is dynamic. End-Systolic Elastance and Pressure-Volume Loops An important limitation of isovolumic and ejection phase indices of contractility (eg, the Frank-Starling relationship) is their significant sensitivity to ventricular loading conditions. To overcome this shortcoming, the use of load-independent indices has been explored. On a pressure-volume diagram, points defined by the end-systolic pressures and volumes of the several contractions will be positioned on a single line. The intraoperative determination of contractility by this technique has been hampered by difficulties in obtaining accurate ventricular volumes and pressures. Continuous left ventricular pressure-volume loops may be displayed during cardiac surgery using left ventricular conductance and micromanometry catheters that are introduced through the pulmonary veins. Pulse Oximetry Pulse oximetry is one of the most important anesthesia monitoring technologies and has been accepted as a worldwide intraoperative monitoring standard. Postoperative complications (eg, cardiovascular, respiratory, neurologic, infectious) did not differ between patients monitored with or without pulse oximetry. The advantages and limitations of the technique merit discussion to prevent misinterpretation of the data provided by pulse oximetry devices. Oxyhemoglobin absorbs mostly infrared light (850 nm to 1000 nm) and transmits mostly red light (600 nm to 750nm), whereas deoxygenated Hb absorbs more red light and infrared light passes through. The pulse oximeter uses this principle to determine the relative concentration of oxyhemoglobin in the blood. Several things in addition to arterial blood also absorb red and infrared light in the tissues. These include capillary blood, venous blood, melanin in the epidermal skin layer, cytochrome c oxidase within the mitochondrial respiratory chain and, to a lesser extent, in soft tissue, fat, and bone. The pulse oximeter uses this pulsatile component of the light absorbance to calculate the arterial oxygen concentration. Some of these factors include diminished tissue perfusion (eg, limb ischemia, hypothermia, vasoconstricting drugs), ambient light, intravenous dyes, carboxyhemoglobin, and methemoglobin. Regarding a poor plethysmography tracing with a saturation of 85% as possibly representing artifact and confirming the result with an independent technique are both important. It must also be recognized that standard blood gas analyzers calculate or derive the arterial saturation based on the measured partial pressure of oxygen (PaO2) in the blood, which may cause significant errors in accurately determining low blood saturations. Another problem in cardiac procedures is that the plethysmography tracing often decreases in amplitude over the course of the procedure until the signal-to-noise ratio is too low for accurate oximetry. The overall incidence of cases that had at least one continuous gap of 10 minutes or more in pulse oximetry data was 31%. Intraoperative hypothermia, hypotension and hypertension, and duration of procedure also were independent risk factors. The primary disadvantage of pulse oximetry, however, is that the PaO2 must fall below 100 mm Hg before the device will begin to detect any change, and below 60 mm Hg before rapid changes will occur. Thus the device is not sensitive to changes in PaO2 over wide ranges that are of clinical significance. Despite many years of clinical experience, no convincing outcome data demonstrate the superiority of more invasive versus less invasive monitoring techniques. Oxygen is bound to Hb and is also dissolved in the plasma (to a much smaller extent). Optimization of these parameters are then allowed to improve delivery and uptake of the proper amount of oxygen to the tissues. Tachycardia is also detrimental because it decreases coronary filling time and increases oxygen demand. American Society of Anesthesiologists and Society of Cardiovascular Anesthesiologists Task Force on Transesophageal Echocardiography. Evaluation of the aorta-to-radial artery pressure gradient in patients undergoing surgery with cardiopulmonary bypass. Transmural right ventricular blood flow during acute pulmonary artery hypertension in the sedated dog. Systolic pressure variation: a dynamic measure of the adequacy of intravascular volume. Implications of arterial pressure variation in patients in the intensive care unit. A comparison of systolic blood pressure variations and echocardiographic estimates of end-diastolic left ventricular size in patients after aortic surgery. Evaluation of dynamic performance in liquid-filled catheter systems for measuring invasive blood pressure. Effect of the dynamic response of transducer-tubing system on accuracy of direct blood pressure measurement in patients. The fast-flush test-is the clinical comparison equivalent to its in vitro simulation The fast-flush test measures the dynamic response of the entire blood pressure monitoring system. Frequency response evaluation of radial artery catheter-manometer systems: Sinusoidal frequency analysis versus flush method. Briefly, cerebral tissue saturations reflect a mostly venous-weighted signal that is measured continuously. Thus it correlates strongly with jugular bulb saturation, with higher readings attributable to the 25% to 30% admixture of arterial blood in cerebral tissue. Its use in cardiac surgery has been steadily increasing, attributable to the noninvasive nature of the technology and the magnitude of clinically relevant data that can be derived. Trend monitoring from a baseline value obtained during hemodynamically stable conditions, as well as absolute lower thresholds, have been recommended in clinical practice for decision making. Dynamics of invasive pressure monitoring systems: Clinical and laboratory evaluation. Minimized mortality and neurological complications in surgery for chronic arch aneurysm: axillary artery cannulation, selective cerebral perfusion, and replacement of the ascending and total arch aorta. Axillary artery cannulation: routine use in ascending aorta and aortic arch replacement. Cannulation of the axillary artery for cardiopulmonary bypass: safeguards and pitfalls. Arterial pressure monitoring during cardiopulmonary bypass using axillary arterial cannulation. Comparison of axillary artery or brachial artery pressure with aortic pressure after cardiopulmonary bypass using a long radial artery catheter. Can we trust the direct radial artery pressure immediately after cardiopulmonary bypass Differences between aortic and radial artery pressure associated with cardiopulmonary bypass. Evaluation of peripheral arterial pressure in the thumb following radial artery cannulation. Thromboangiitis obliterans: methods of diagnosis of chronic occlusive arterial lesions distal to the wrist with illustrated cases. A simple method to determine patency of the ulnar artery intraoperatively prior to radial artery cannulation. Alternative arterial catheterization site using the ulnar artery in critically ill pediatric patients. Comparison of brachial and radial arterial pressure monitoring in patients undergoing coronary artery bypass surgery. Brachial artery catheterization: an assessment of use patterns and associated complications. Complication rates of percutaneous brachial artery access in peripheral vascular angiography. Clinical review: complications and risk factors of peripheral arterial catheters used for haemodynamic monitoring in anaesthesia and intensive care medicine. Indications and complications of arterial catheter use in surgical or medical intensive care units: analysis of 4932 patients. Direct or modified Seldinger guidewire-directed technique for arterial catheter insertion. A prospective comparison of ultrasound-guided and blindly placed radial arterial catheters. Short- axis versus long-axis approaches for teaching ultrasoundguided vascular access on a new inanimate model. Ultrasound-guided radial arterial cannulation: long axis/in-plane versus short axis/out-of-plane approaches Arterial catheter-related bloodstream infection: incidence, pathogenesis, risk factors and prevention. Arterial catheters as a source of bloodstream infection: a systematic review and meta-analysis. Prospective study of peripheral arterial catheter infection and comparison with concurrently sited central venous catheters. Use of full sterile barrier precautions during insertion of arterial catheters: a randomized trial. Centers for Disease Control and Prevention Healthcare Infection Control Practices Advisory Committee. Complications of percutaneous radial artery cannulation: an objective prospective study in man. Radial arterial function following percutaneous cannulation with 18- and 20-gauge catheters. Wrist circumference predicts the risk of radial arterial occlusion after cannulation. Ischaemia of the hand in infants following radial or ulnar artery catheterisation. Open surgical management of complications from indwelling radial artery catheters. Arterial fast bolus flush systems used routinely in neonates and infants cause retrograde embolization of flush solution into the central arterial and cerebral circulation.

NotetheclassicGlennshunt connecting the superior vena cava to the right pulmonary artery and the homografts at the inferior vena cava-right atrial junction and connecting the right atrium to the left pulmonary artery spasms ms robaxin 500 mg buy low cost. Frequently spasms prednisone robaxin 500 mg purchase visa, atrial fibrillation occurs spasms kidney area robaxin 500 mg fast delivery, and the loss of atrioventricular synchrony results in decreased effort tolerance quercetin muscle relaxant discount 500 mg robaxin. The onset of atrial tachyarrhythmias mandates an evaluation of the Fontan pathway with attention turned to relieving any significant obstructions muscle relaxer jokes buy genuine robaxin. In the setting of passive pulmonary blood flow, even small gradients can be very hemodynamically significant. Given the complex anatomy, dilated atrium, and atrial scar with suture lines from prior surgeries, it is not surprising that atrial arrhythmias can become refractory to standard treatment in many patients. Catheter ablation typically has high initial success rates that are not maintained. In a large cohort of patients with atriopulmonary connections, the incidence of bradyarrhythmias requiring pacemakers was 13%. If accompanied by premature atrial contractions, sinus or junctional bradycardia can precipitate an intraatrial reentry tachycardia. Thus sinus node dysfunction also serves as a risk factor for the development of atrial tachyarrhythmias. Pacemakers pose special problems in the Fontan patient because the altered anatomy precludes transvenous placement. Thus Fontan patients who require pacing will have epicardial leads placed via repeat sternotomy with all the accompanying risks. Even though atrioventricular synchrony can be achieved with pacing, it is still not as desirable as intrinsic sinus rhythm. The incidence of sinus node dysfunction is less with a cavopulmonary versus an atriopulmonary connection. The incidence is quoted as high as 15%, but a large international multicenter study found a rate of 3. Serum albumin is low and the diagnosis is confirmed by finding enteric protein loss with elevated levels of stool 1-antitrypsin. Elevated portal pressures lead to vascular congestion, lymphatic obstruction, and enteric protein loss from the gut. Any Fontan pathway obstruction should be treated and cardiac output optimized with medical therapy, fenestration, or pacing. The Modern Fontan Operation the atriopulmonary connection proved an inefficient method of pulmonary blood flow. Colliding streams of blood from the superior and inferior vena cavae resulted in energy loss and turbulence within the atrium. The lateral tunnel Fontan improved pulmonary blood flow, and only the lateral wall of the atrium was exposed to central venous hypertension. The extracardiac Fontan is a further modification of the total cavopulmonary connection. It is not yet certain if the development of long-term complications has been truly reduced or only delayed. Preoperative Assessment Patients with Fontan physiology are presenting in larger numbers for the entire array of noncardiac surgery, including obstetric procedures. Preoperative assessment begins with a directed history, concentrating on functional status and the presence of major complications. Heightened suspicion is clearly needed for patients with atriopulmonary connections and for those with a systemic right ventricle. Normal ventricular function on echocardiogram would stratify the patient as "low risk" only within the context of patients with Fontan circulation. A term that should immediately get the attention of the anesthesiologist is failing Fontan. Specific reasons for failing may differ, but the common denominator in these patients is a marked limitation of functional status. If loss of sinus rhythm is accompanied by severe tachyarrhythmias, Fontan conversion surgery is indicated. Aortopulmonary collaterals result in a progressive volume load on the single ventricle. Collaterals from the venous system to the systemic atrium or ventricle cause hypoxemia. In both cases large collaterals should be coil occluded in the catheterization laboratory. Another option is the creation of a fenestration, which can improve cardiac output and lower central venous pressures but at the expense of a right-to-left shunt. Unfortunately, not all of these therapeutic options are indicated or successful in every patient. At this point, if no realistic hope of further improvement exists, the only option is cardiac transplantation. The functional state of Fontan patients exists across a spectrum but generally falls into two groups. These patients will tolerate most surgical procedures with an acceptably low risk. The second group is smaller but consists of those patients who have manifested one of more of the "failing Fontan" criteria. When it comes to a discussion of anesthetic technique, the same lessons learned in caring for patients with acquired coronary artery disease apply. That is, there is no right drug for these patients, nor is there a single "best" anesthetic technique. Certain principles for patients with Fontan physiology are important and need to be stressed (Box 22. The physiologic changes of pregnancy are well known and described in standard texts. The dilemma facing physicians caring for these patients is that Fontan patients are known to have decreased cardiac reserve, even those who report good functional status. One series of 33 pregnancies found women tolerated pregnancy, labor, and delivery well but there was an increased risk of spontaneous abortion. First, pregnancy is usually undertaken only in those patients with relatively good functional status, thereby removing the highest risk patients. Undoubtedly, most adult congenital cardiologists would counsel against pregnancy in any patient with evidence of a failing Fontan circulation. In patients with good functional status, pregnancy can successfully be carried to term, albeit with increased risk of miscarriage and premature delivery. A review of the case reports in the anesthetic literature shows that epidural analgesia is well tolerated and indeed recommended for the first stage of labor. Perioperative complications are low, and peripartum cardiac decompensation is rare. Case reports and small case series began to appear in the literature in the mid-1990s. At this time, interest focused on the best indications for this major surgery, outcome predictors, and optimizing the surgical technique. It was believed that conversion of an atriopulmonary Fontan to the improved hemodynamics of the modern Fontan would relieve severe atrial arrhythmias. The profile of the early patient undergoing Fontan conversion surgery was one of refractory atrial arrhythmias and poor functional state. Second, arrhythmia control was much better in the group that underwent extracardiac connection with arrhythmia surgery. Conversion to extracardiac Fontan without an ablative procedure resulted in a high rate of arrhythmia recurrence. The largest experience came from Mavroudis, whose preferred technique was conversion to an extracardiac Fontan with intraoperative electrophysiologic mapping, arrhythmia ablation, and pacemaker placement. These encouraging results give hope to the many patients with atriopulmonary connections and poor functional status. Patients should not have multiple failed attempts at arrhythmia ablation in the catheterization laboratory because of a fear that surgery is associated with an unacceptably high mortality. The ideal patient is one with refractory arrhythmia and poor functional status despite adequate ventricular function. Preoperatively, the important factors are the degree of arrhythmia control and the ventricular function. They may be in sinus rhythm, but it is more likely they have an atrial arrhythmia with some degree of ventricular rate control. The underlying ventricular function may be poor due to longstanding arrhythmia, made worse by the negative inotropic effect of antiarrhythmic medications. Intravenous induction can be prolonged because blood moves sluggishly through the greatly dilated atrium. Airway management needs to be prompt and skilled, as it does for all Fontan patients. Once safely through induction and intubation, large-bore intravenous access must be established. This is usually not a problem because the central venous hypertension of Fontan patients creates dilated peripheral veins. Small central venous catheters are appropriate for delivering inotropic drugs and monitoring but some centers will prefer to place transthoracic atrial lines and completely avoid central access for fear of thrombosis. Transesophageal echocardiography is routinely used to assess volume status and ventricular function, as well as to exclude intracardiac thrombus. The repeat sternotomy, usually at least the third, can be especially bloody because of the raised central venous pressure. Also, a plan should be worked out with the surgeon and perfusionist for emergency establishment of femoral bypass if necessary. Patients with pacemakers are vulnerable to electromagnetic interference because the repeat sternotomy requires extensive use of electrocautery in close proximity to the heart and pacemaker generator. If the patient is pacemaker dependent, consideration should be given to reprogram the device to an asynchronous mode. Finally, aggressive management of coagulation is required, and in this regard there is no substitute for point-of-care testing to guide transfusion products. The anesthetic considerations for Fontan conversion surgery have been reviewed in detail. The progression of pulmonary vascular disease is relatively accelerated when compared with patients with other types of right-to-left shunts with equivalent degrees of shunting. The development of pulmonary vascular disease is dependent on the volume and pressure of the right-to-left shunt. With time, the ductus can become calcified or aneurysmally dilated with a risk of rupture. With calcification and friability of the ductus, if device closure is not practicable, it is possible to do a patch closure from inside the aorta or pulmonary artery. Almost all patients who have relief of stenosis either surgically or by balloon valvuloplasty have normal right ventricular function postoperatively, although surgical reintervention may be required in a significant number in the long term. However, abnormal ventricular function may not resolve after late surgical correction. The development of isolated pulmonary valvular stenosis, even of a severe degree, is usually well tolerated during pregnancy, even in the face of the volume overload that accompanies pregnancy. Coronary ischemia resolves if coronary perfusion pressure is increased, as with use of phenylephrine. Single Ventricle See the Fontan Physiology section earlier in this chapter for a detailed discussion. Tetralogy of Fallot As with many things in medicine, tetralogy of Fallot was first described by someone else-probably in 1673 by Stenson. However, there is a spectrum of disease with more severe defects including stenosis of the pulmonary valve, stenosis of the pulmonary valve annulus, or stenosis and hypoplasia of the pulmonary arteries in the most severe cases. Tetralogy of Fallot is the most common cyanotic lesion encountered in the adult population. Unrepaired or nonpalliated, approximately 25% of patients survive to adolescence, after which the mortality is 6. The 32- to 36-year survival has been reported to be 85% to 86%, although symptoms, primarily arrhythmias and decreased exercise tolerance, occur in 10% to 15% at 20 years after the primary repair205­208 (Box 22. In the past, most children with tetralogy were managed with a preliminary palliation with an aortopulmonary shunt such as a Blalock-Taussig, followed by complete correction. Currently, most children are managed with a complete repair in infancy, without preceding palliation. However, it can be encountered in immigrants or in patients whose anatomic variation was considered to be inoperable when they were children. In tetralogy, the right ventricle "sees" the obstruction from the pulmonic stenosis. Shunting is minimized, however, by pharmacologically increasing systemic vascular resistance. The increase in systemic vascular resistance decreases right-to-left shunting and diminishes cyanosis but at the expense of right ventricular or biventricular failure. Increases in the inotropic state of the heart increase the dynamic obstruction at the right ventricular infundibulum and worsen right-to-left shunting. Although halothane was the historic anesthetic of choice in children with tetralogy due to its myocardial depressant effects and ability to maintain systemic vascular resistance, current practice is to use sevoflurane, without undue consequence from a reduction in systemic vascular resistance. However, unlike the more usual bundle-branch block in adults, this represents disruption of the HisPurkinje system only in the right ventricular outflow, in the area of the right ventricular incision. Because the vast majority of His-Purkinje conduction is intact, it does not carry increased risk for the development of complete heart block. Some patients require repair of pulmonic stenosis by placement of a transannular patch, with obligate residual pulmonary insufficiency.

The primary determination of flow is the pressure differences in the two chambers uterus spasms 38 weeks generic robaxin 500 mg with amex. The velocity sweep speeds of 25 to 50 mm/sec should be initially used to evaluate respiratory variations in flow that may occur with pulmonary or pericardial disease spasms tamil meaning buy robaxin 500 mg on line, after which it may be increased to 100 mm/sec muscle relaxant methocarbamol addiction order generic robaxin canada. With impaired relaxation muscle relaxant that starts with a t buy robaxin with amex, the A-wave velocity increases muscle relaxant pregnancy safe buy robaxin 500 mg without a prescription, and the E/A ratio becomes less than 0. Further progression to restrictive cardiomyopathy results in the rapid increase in ventricular pressure during early diastole with resultant shortened early diastolic filling. Pulmonary Venous Flow Analysis the pulmonary veins may be imaged from a number of views as described earlier. Recommendations for the evaluation of left ventricular diastolic function by echocardiography. If both S1 and S2 components of the pulmonary systolic flows are present, then the S2 velocity should be used for calculations because S1 is related to atrial relaxation. After measuring of the transmitral Doppler spectrum, the difference between the atrial reversal duration and the A-wave duration should be calculated. The atrial systole component of the pulmonary venous flow (ie, atrial reversal) velocity is usually less than 35 cm/sec, and its duration is usually less than the transmitral E-wave duration. Color M-Mode Flow Propagation Velocity Mitral-apical propagation velocity (Vp) may be measured using color M-mode imaging. Tissue Doppler Spectral Doppler is usually used to determine blood-flow velocities. Because these velocities are relatively high and the amplitude of the Doppler signal is low, high amplitude­low velocity ultrasound signals are usually ignored. In contrast, during tissue Doppler examination, the primary interest is in the high amplitude­low velocity ultrasound signals created by the myocardium; low amplitude­high velocity signals are ignored. The sample volume should be positioned with 1 cm of the septal and lateral annular insertion points and should cover the longitudinal excursion of the mitral annulus in both systole and diastole. The peak e- and a-wave velocities should be determined, and both the e/a and E/e ratios should be calculated. Because preload has minimal effect on e-wave velocity, the E/e ratio is useful to correct for E-wave velocities in the presence of diastolic dysfunction. Other supporting data for the diagnosis of moderate diastolic dysfunction include an increase of the E/e ratio from 9 to 12, e less than 8 cm/sec, a pulmonary venous atrial reversal wave velocity greater than 30 cm/sec, the diastolic pulmonary venous blood-flow velocity greater than the systolic velocity, and the difference between pulmonary venous atrial reversal duration and transmitral A-wave (Ar-A) duration of 30 milliseconds or longer. In the intermediate E/A ratios or a high E-wave velocity, other indices must be considered as well. For intermediate values of E/e ratio, other factors associated with diastolic function must be considered. Right Ventricular Function the right ventricle is a complex structure that pumps venous blood to the normally low pressure­low resistance pulmonary arterial circuit. Unlike the left ventricle, which has a pistonlike contraction, the right ventricle contracts in a peristalticlike manner with contraction of the inflow, followed in sequence by the apical and outflow portion. Right Ventricular Anatomic Assessment As previously described, the right ventricle is particularly sensitive to increases in afterload. Current chamber quantification guidelines suggest upper reference values for a diameter of 4. Because the septal segment of the tricuspid annulus is fixed, the longitudinal contraction of the right ventricle causes a hingelike movement of the lateral annulus. Flow velocities of 1 and 2m/sec are marked, and the time interval between them is measured, converting millisecondstoseconds. If blood passes through an area of stenosis, then the potential energy (as represented by high pressure) must be converted into kinetic energy as observed as high blood-flow velocities. In addition, if the system is pulsatile, then some energy will be expended for blood acceleration and deceleration. Finally, some energy will be lost as heat by the viscous forces generated by friction. These relationships have been described by Bernoulli as: p1 - p2 = 1 2 (v 22 - v12) + (dv dt)ds + R(µ) [Eq. The first term represents the kinetic energy expenditure that results in the acceleration of blood over the obstruction. The second term of the equation represents unsteady acceleration and deceleration of pumping blood. During clinical application, the energy expended attributable to the cyclic acceleration and deceleration, as well as the energy loss attributable to viscous forces, are both negligible and may be ignored, leaving just the first term. Because both velocities are squared and v2 is significantly larger than v1 (v2 v1), v1 may be ignored as well, the equation may be simplified to: p1 - p2 = 0. It may be applied to the measurement of intravascular pressures, as well as the gradient across a stenotic orifice. When compared with direct measurements, some of these techniques yielded highly accurate correlations (r = 0. Because flow velocity is not constant throughout a flow cycle, all of the flow velocities during the entire ejection period are integrated to measure "distance traversed" of this "region of blood. Multiple regions of interest points may be seen, indicating range ambiguity of the cursor. If the velocities are too high, then localizing the jet without assumptions is not possible. The end-systolic dimension is best measured at the time of the peak downward motion of the posterior endocardium. Other methods using the mitral, tricuspid, and pulmonic orifices have been attempted with variable results. Their respective accuracy is dependent on the angle between the insonated Doppler signal and blood flow. The derivative of a function is the slope of the curve at a given point, whereas an integral of a function is the area under the curve between two points along its X axis. Similarly, given a graph of acceleration versus time, the integral would yield a velocity measurement; the integral of a velocity-versus-time graph would yield a distance traversed (ignoring initial conditions). A second source of variability in measuring flow involves the proper recording of reproducible Doppler signals. Occasionally, the Doppler signal is difficult to obtain, and the morphologic structure of the spectrum may be similar to a triangle with a spike at the peak velocity rather than a round "bell-shape" flow signal. The measurement of the mitral orifice diameter should probably be repeated at various angles. It has been well established that the size of the mitral orifice varies with varying flows. The importance of the sample volume location has been demonstrated in several studies. LaMantia and associates,129 who performed a similar study in 13 cardiac surgical patients, found only a modest correlation (r = 0. In contrast, Savino and associates130 found good agreement and correlation (r = 0. In addition, the method was tedious and not suitable for online analysis with current equipment and software. They observed a good correlation between these two measurements; however, there were significant bias and wide limits of agreements among the measurements. It should be noted, however, that each measurement required approximately 3 minutes per case, and poor image quality precluded analysis in four patients. As described earlier, homogeneous laminar flow and a cylindrical outlet is assumed during Doppler measurements. Real-time three-dimensional color Doppler echocardiography overcomes the inaccuracies of spectral Doppler for stroke volume calculation. Noncardiac intraoperative applications include assessment of perfusion in the kidney and in skeletal muscle. Work is ongoing to investigate the potential for analyzing cerebral blood flow with contrast-echocardiographic techniques. The images are processed such that the linear scatters from tissue are completely eliminated, leaving only nonlinear scatters from the bubble contrast. In addition, its use decreases interobserver variability associated with these measurements and increases the number of myocardial segments that may be accurately described during stress echocardiography. These saline solutions can be easily prepared by hand agitation of saline between two 10-mL Luer lock syringes connected by a three-way stopcock; small amounts of blood or air may be added to improve right-sided opacification. This technique is most commonly used to opacify the right atrium and right ventricle, assisting in the diagnosis of intraatrial and ventricular shunts and to enhance pulmonary arterial Doppler signals. After obtaining a bicaval view, a Valsalva maneuver is induced, and hand-agitated saline is injected into a large vein. Aortic Dissections Echocardiographic contrast may be used to diagnosis aortic dissections. Artifacts may be distinguished from true aortic dissection and artifact by the homogeneous distribution of contrast within the aortic lumen. Theimageontheleftiswithout contrast and the image on the right is after contrast enhancement. The contrast-enhanced image clearly demonstrates the high-velocity envelope consistent with aortic stenosis that could not be visualized withoutcontrast. American Society of Echocardiography Consensus Statement on the Clinical Applications of Ultrasonic Contrast Agents in Echocardiography. Lindner and colleagues143 described a method for the quantification of myocardial blood flow using contrast echocardiography. If a contrast agent is administered at a steady rate, then the blood concentration and myocardial concentration of the contrast agent will equilibrate. The rate of contrast replenishment in the myocardium is directly related to myocardial blood flow. Myocardial-contrast echocardiographic-derived indications of myocardial perfusion rate have relatively good between-study and between-reading reproducibility. A fixed myocardial deficit may be diagnosed with a perfusion deficit during rest and stress with akinetic segments during both of these periods. Myocardial stunning may be diagnosed if normal perfusion is observed during rest in the presence of a hypokinetic rest wall motion, and hibernation may be diagnosed with rest hypoperfusion and with hypokinetic rest wall motion. They detected significant coronary artery stenosis in 43 patients involving 69 coronary areas. The use of contrast further increases the successful differentiation between the true and false lumen. The valve has three fibrous cusps, right, left, and noncoronary, that are attached to the root of the aorta. Each cusp has a nodule, the nodule of Arantius, in the center of the free edge at the point of contact of the three cusps. The spaces between the attachments of the cusps are called the commissures, and the circumferential connection of these commissures is the sinotubular junction. The aortic ring is at the level of the ventricular septum and is the lowest and narrowest point of this complex. Doppler Enhancement the administration of contrast will enhance the echocardiographic Doppler spectrum, in which the signal is weak or suboptimal. Whereas the threshold for detecting contrast is substantially less for Doppler, compared with 2D imaging, contrast agents are usually used initially for the latter application. Myocardial Perfusion the second-generation agents allow for perfusion of the myocardial microcirculation. With severe calcification, echocardiographic shadowing is significant, which limits the accuracy of this measurement. Ahigh-velocity jet is appreciated, which is consistent with severe aortic stenosis. The higher velocity central jet is characterized by a high-pitched audio sound and a fine feathery appearance on the Doppler signal and is usually less dense than the thicker parajets that are distal to the valve. Peak and mean transvalvular gradients may be calculated using the peak and mean velocities of the signals, respectively. Peak gradients measured by Doppler ultrasonography tend to be higher than those measured in the cardiac catheterization laboratory because Doppler-determined peak gradients are instantaneous, whereas those reported by the cardiac catheterization laboratory are peak-to-peak systolic pressure differences. Distal to the orifice, flow decelerates again with both conversion of this loss of kinetic energy into heat, as well as a reconversion of some kinetic energy into potential energy with a corresponding increase in pressure. The continuity equation describes the conservation of a physical quantity, that is, energy and mass. Blood flow in one portion of the heart must be equal to the blood flow in another portion of the heart. Cusp pathologic conditions (eg, redundancy, restriction, mobility, thickness, integrity), commissural variations (eg, fusion, splaying, alignment, attachment site), and root morphologic characteristics (eg, septal hypertrophy, root dimensions) should be ascertained. The cusp prolapse may be further subdivided: cusp flail, partial cusp, and whole-cusp prolapse. This may be a result of thickened, rigid, or destroyed valves attributable to endocarditis or calcification. Functional anatomy of aortic regurgitation: accuracy, prediction of surgical repairability, and outcome implications of transesophageal echocardiography. The dotted lines represent the attachment of the leaflet tips to the sinotubular junction. Normally the leaflet tips coapt fully in diastole (short-axis view) and that the diameter of the sinotubular junction is similar to that at the base of the annulus. This panel shows incomplete leaflet closure when the sinotubular junction dilates (arrows) relative to the aortic annulus, resulting in leaflet tethering and a persistent diastolic orifice. Midesophageal aortic valve long-axis view demonstrates (left)therightcoronarycusp (most anterior) prolapsing into the left ventricularoutflow tract. Nyquist limits should provide an aliasing velocity of approximately 50 to 60 cm/sec and a color gain that just eliminates the random color speckle from nonmoving regions. In addition to providing the regurgitant jet area, the origin and width of the jet and the spatial orientation should be carefully defined.

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References

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