Michael Zucker MD

• Professor of Clinical Radiology, Emeritus, David Geffen School of Medicine at
• University of California Los Angeles, Los Angeles, California

Multi-society consensus quality improvement guidelines for the treatment of lower extremity superficial venous insufficiency with endovenous thermal ablation from the Society of Interventional Radiology symptoms before period amoxicillin 250 mg purchase with amex, Cardiovascular Interventional Radiological Society of Europe adhd medications 6 year old amoxicillin 500 mg purchase on-line, American College of Phlebology and Canadian Interventional Radiology Association treatment cervical cancer 250 mg amoxicillin purchase amex. Multi-disciplinary quality improvement guidelines for the treatment of lower extremity superficial venous insufficiency with ambulatory phlebectomy from the Society of Interventional Radiology treatment of hemorrhoids discount amoxicillin 500 mg buy on line, Cardiovascular Interventional Radiological Society of Europe medicine recall best amoxicillin 500 mg, American College of Phlebology and Canadian Interventional Radiology Association. In addition, many biopsies are performed in oncologic patients with residual masses after therapy to determine whether such a mass represents residual viable tumor or necrotic tissue. These needles obtain a cytologic aspirate that is sufficient to confirm or refute a diagnosis of malignancy, but that often is not able to provide a specific histologic diagnosis. The advantage of core biopsy needles is that cores of tissues retain the organization of the lesion, often allowing precise histologic diagnosis of malignant tumor type or confidently allowing the diagnosis of benignity. Advantages of fine-needle biopsy include the ability to traverse bowel without ill effect, and the likelihood of inducing hemorrhage when sampling vascular lesions is minimal. Large-gauge needle biopsies (14- to 19-gauge) are almost universally performed with a spring-activated, modified Tru-Cut system (Box 17-2). If the lesion to be biopsied is superficial, such as in the neck, coagulation studies are not required, because direct pressure will achieve hemostasis if bleeding occurs. Fine-Needle Biopsy (20- to 25-Gauge) Proper technique more important than needle type Can traverse bowel if necessary Computed tomography or sonographic guidance Nonaspiration technique for vascular lesions Coaxial or tandem technique can be used Often sufficient when known primary neoplasm present Box 17-2. Advantages are (1) ease of use, (2) ability to hold the biopsy gun with one hand, which is particularly important when using ultrasound guidance, and (3) uniform consistency in size and amount of tissue obtained. In general, large-gauge automated needle biopsies are performed in patients in whom there is no known primary tumor, when there is a possibility of lymphoma, or after fineneedle biopsy has failed (see Box 17-2). In recent years, this distinction between large-gauge biopsy and fine-needle biopsy has become blurred because of the development of 20-gauge automated Tru-Cut needles. These needles are now used more and more frequently, particularly when an experienced cytopathologist is not present for the biopsy procedure. Although magnetic resonance interventional systems are used in clinical practice, their role in performing routine biopsies is limited by cost and lack of widespread availability. All neck and soft tissue lesions, most liver lesions, large abdominal masses, and some pancreatic lesions can be biopsied under sonographic guidance. The needle (arrow) is then inserted at the short end of the transducer, and with proper alignment in the ultrasound beam, the entire needle shaft should be visible at all times. If the needle (arrows) is inserted at an angle to the direction of the ultrasound beam, the full length of the needle is not seen and the biopsy is difficult to perform. There are many commercially available biopsy guides that can be fitted to existing ultrasound transducers that will direct the needle into the path of the ultrasound beam. The freehand technique offers more flexibility in that needle position and angle adjustments can be made as the biopsy is being performed to correct or realign the needle path if necessary. The needle is aligned with the ultrasound beam and inserted through the anesthetized skin and subcutaneous tissues toward the lesion to be biopsied. When experience is gained with sonographically guided freehand biopsy methods, this becomes a very rapid and reliable method of guiding biopsy needles to the target in question. Sonographic guidance can be problematic in obese patients because the echogenic needle can be hard to visualize in the echogenic soft tissues. Alternatively, a homemade phantom can be constructed by taping together approximately ten 15-cm lengths of 4- or 5-French catheters at 1-cm intervals. Performing the Biopsy Fine-Needle Aspiration Biopsy A 10-mL syringe is applied to the hub of the needle that has been inserted into the lesion, and suction is applied. While suction is applied, the needle is moved quite firmly in a to-and-fro motion through the lesion for approximately 10-15 seconds or until blood appears in the hub of the needle. Suction is released while the needle is being removed to prevent aspiration of cells along the needle track that may confuse the cytologic interpretation of the sample. Ideally, a cytologic technician should be available to handle the specimen and a cytopathologist should be in attendance to render a preliminary report. If after four or five samples have been obtained a diagnosis is still not forthcoming, a large-gauge core biopsy sample should be obtained. Visualization of the needle is aided by a gentle rocking Nonaspiration Fine-Needle Biopsy movement of the transducer and a slight to-and-fro jiggling motion of the needle. The nonaspiration technique is particularly valid for hemorrhagic organs such as the thyroid and occasionally hemorrhagic lesions within the liver. Using the nonaspiration technique, the needle is inserted into the lesion and again multiple to-and-fro motions through the lesion are performed until either blood appears in the hub of the needle or 15 seconds have elapsed. This technique has not found widespread acceptance, although it is useful, in combination with aspiration cytology for biopsy of thyroid lesions. The coaxial technique has several advantages in that only one puncture is made into the organ, reducing the propensity for hemorrhage or other complications. Further needles are inserted in tandem to the reference needle and are placed to the same depth and follow the same trajectory as the reference needle. If the needle is not in an appropriate position, further needles can be inserted and scanned (using the first needle as a guide for adjusting the trajectory of further needles) until an appropriate position within the lesion is obtained. When biopsying peripheral lesions on the edge of the liver, it is best to try to traverse some normal liver before entering the lesion. Although generally a safe procedure, complications such as pneumothorax, hemothorax, and failure to obtain liver tissue occurred in patients with slightly abnormal anatomy. The liver capsule is also infiltrated with local anesthetic, which can be painful; the patient should be warned and asked not to move. Additionally, the larger needle can be manipulated at the skin so that it points in different directions for sampling different parts of the lesion. B, Using freehand ultrasound technique, the lesion was biopsied using first fine needles and then an 18-gauge automated Tru-Cut needle. The stomach is avoided if possible, but if impossible, the stomach can be punctured with 20- or 22-gauge needles to access the pancreas. A useful alternative is to use a 20-gauge automated Tru-Cut needle, particularly when a cytologist is not in attendance for the biopsy. When a fluid-filled pancreatic lesion such as a cystic tumor is encountered, it is vitally important not to transgress the colon with a small-gauge needle en route to the lesion. In general, core biopsies are needed for renal masses because sufficient tissue to differentiate metastases from primary tumors or to subtype lymphoma is required. Adrenal Glands the need for adrenal biopsy has decreased dramatically with the recent introduction of lipid-sensitive imaging techniques for differentiating benign from malignant adrenal masses. Because of their position, high up in the retroperitoneum, the adrenal glands can pose problems for biopsy in that a direct posterior approach often passes through lung. B, In this case, biopsy of the edge of the lesion is mandatory because a sample from the center of the lesion would be unrepresentative of the whole. A, Dynamic computed tomography through the head of the pancreas before biopsy reveals a small mass in the uncinate lobe of the pancreas. Pancreatic Biopsy Computed tomography guidance often necessary Stomach avoided if possible Accuracy improved by giving intravenous contrast Maximal suction often necessary Do not traverse colon en route to a cystic lesion 20-gauge cutting needle is a useful addition (right adrenal gland), the left anterior transhepatic approach (left adrenal), the angled posterior approach, and the lateral decubitus approach. The lateral decubitus approach works on the principle that when a patient is placed in the lateral decubitus position, the underlying lung expands less than the overlying lung. Occasionally in thin individuals retroperitoneal masses can be visualized with sonography using a posterior approach and the psoas muscle as an acoustic window. Whereas a level of up to 4 ng/mL is considered within normal limits, a level greater than 4 ng/mL does not specifically imply cancer. The patient was referred for biopsy rather than surgical removal because of the possibility that the mass represented recurrent lymphoma. Ultrasound guidance using a transrectal probe is used for both, but in the transperineal route, the needle is placed through the skin of the perineum, while in the transrectal route the needle is passed through the rectal wall. The author prefers the transrectal route because it is faster, requires no local anesthesia, and with appropriate antibiotic coverage, the infection rate is minimal. D represents the diaphragm, the shaded area represents the abdominal cavity, and the white area above the diaphragm represents the lung. To ensure that clot retention, which may lead to bladder obstruction, does not occur, the patient is asked to pass urine before leaving the department. The patient is told to expect hematuria and/or blood in the ejaculate for 24 hours and is instructed to return to the emergency department if he is unable to pass urine or fever develops. In this patient, using a lateral decubitus position, a direct posterior approach was used to biopsy the adrenal lesion (arrows) because the intervening lung becomes hypovolemic and no longer is in the path of the needle. With the advent of endocavitary ultrasound probes, access to pelvic lesions is now possible via the transvaginal and transrectal routes. When using the transvaginal approach, the posterior fornix is infiltrated with local anesthetic and a 20- or 22-gauge needle passed into the lesion. Patients with pancreatic cancer or other malignancies in the upper abdomen respond well to celiac axis ablation (70%-80% response rate). Not only is it necessary to differentiate lymphoma from carcinoma, but it is also necessary to differentiate Hodgkin from non-Hodgkin lymphoma and to subtype the Hodgkin or nonHodgkin lymphoma. The majority of deaths were due to hemorrhage after liver biopsy, with the next major cause of death being pancreatitis after pancreatic biopsy. Hemangiomas can be characterized with either liver magnetic resonance imaging or nuclear scintigraphy, and the need for biopsy is thus avoided. In addition, superficial liver lesions should not be punctured directly; rather, the needle should be angled obliquely to pass through normal intervening liver tissue, which should tamponade any bleeding. Other measures to reduce the number of complications from liver biopsy include the correction of any bleeding diathesis and/or plugging the biopsy track with Gelfoam after performing the biopsy in patients with bleeding diathesis. Two or three 18-gauge core biopsy samples generally ensure that the cytopathologist has enough tissue to render a diagnosis and to subtype. Accuracy rates in the retroperitoneum tend to be a little lower than in the liver and other locations in the abdomen; biopsy of lymphomas in the retroperitoneum decreases accuracy. After the procedure is finished, the patient is taken to a nursing observation area and vital signs are recorded every 15 minutes for 2 hours in patients who have had fine-needle biopsies and for 3-4 hours in patients who have had a large-gauge needle biopsy. Patients are instructed to rest at home after the biopsy and are given information regarding the procedure that was performed, symptoms that may herald complications, and contact numbers for the interventional radiology department. Conversely, bronchoscopy is less likely to yield a specific cytologic diagnosis in peripheral nodules, which are best approached percutaneously. Contraindications to thoracic biopsy are relative and include severe chronic obstructive pulmonary Complications of Abdominal Biopsy Complications related to fine-needle abdominal biopsy are rare. Celiac Ganglion Block Computed tomography guidance preferred One or two needles placed adjacent to celiac axis 20-40 mL of alcohol injected Patients with pancreatic cancers respond best Patients with chronic pancreatitis respond less well Box 17-5. Steps to Reduce Complications Avoid biopsying liver hemangiomas For superficial liver lesions, traverse normal liver parenchyma Correct bleeding diathesis Plug the biopsy track with Gelfoam if bleeding diathesis, or consider a transjugular liver biopsy Do not biopsy "normal" pancreas Technique Patient Preparation Informed consent is obtained from the patient, and in particular the possible complication of a pneumothorax is discussed. Some peripancreatic inflammation was present at the time the patient underwent another pancreatic biopsy for possible pancreatic tumor. Preferably a fluoroscopic unit with a C-arm should be used so that needle position can be confirmed on both frontal and lateral projections. A, Plain chest radio- graph showing a cavitating lesion in the left upper lobe (arrows) with associated hilar adenopathy (curved arrows). A 20-gauge needle (arrow) was placed in the periphery of the lesion and 23-gauge needles were used to obtain samples from the posterior wall of the lesion. For large pleural-based lesions or for mediastinal lesions (especially if lymphoma is suspected), a spring-activated modified Tru-Cut 18- or 20-gauge needle biopsy system should be used. In addition, there has been a recent trend toward biopsying more deep-seated pulmonary lesions with 20-gauge spring-activated core biopsy needles. The hypodermic needle used for lidocaine administration is then scanned to check needle course alignment with the lesion to be biopsied. The needle course can be adjusted by withdrawing the needle to the periphery of the lung (taking care not to withdraw the needle outside the pleura) and adjusting the direction of the needle to puncture the lesion. Needle course adjustment can also be aided by patient inspiration or expiration, depending on the location of the needle in relation to the lesion. Additionally the bevel on the needle can be used to steer the needle somewhat toward the lesion, particularly when small adjustments are necessary. The outer coaxial needle is inserted 2-3 mm into the superficial edge of the lesion to be biopsied so that it has some purchase within the lesion during coaxial biopsies. This is usually accomplished by first placing a 22-gauge needle into the anterior mediastinal fat and injecting saline to distend the anterior mediastinum. With the mediastinum distended, large-gauge cutting needles can be inserted into the anterior mediastinum without crossing adjacent lung parenchyma. The paravertebral space can be distended by inserting a 22-gauge needle into the paravertebral space and distending this with isotonic saline. It is important, too, to avoid the internal mammary artery and vein, which course in a parasternal location approximately 1 cm lateral to the sternum. The needle is inserted lateral to the internal mammary artery and vein and angled medially, or occasionally Aftercare and Complications Place the patient in the puncture-site-down position with the biopsied site dependent for 2 hours. The puncture-sitedown position helps decrease the amount of air leakage at the biopsy site because the weight of the lung itself helps oppose the two pleural layers. If the pneumothorax is moderate or large, or if the patient is symptomatic, the patient is admitted to hospital and the pneumothorax treated. If hemoptysis is moderate, the patient can be placed in the lateral decubitus position with the biopsied lung dependent to prevent aspiration of blood into the contralateral lung. Air embolism may be facilitated by leaving the needle open to the air while the needle is in the chest, or by deep breathing or coughing by the patient. Treatment includes administration of 100% oxygen, placing the patient in the left lateral decubitus position, with the head down (to prevent cerebral air embolism), and/or transfer to a hyperbaric unit. A negative result often leads to a repeat biopsy, with positive results being obtained in as many as 35%-45% of patients undergoing repeat biopsies. In patients with previous thyroid cancer, it is useful to send samples for markers of thyroid cancer as well as for cytologic analysis. The needle used to take the cytology sample is simply rinsed with 1 mL of saline into a sterile tube and sent to the endocrine laboratory for calcitonin or thyroglobulin analysis. In patients with metastatic lymph nodes, the thyroglobulin is dramatically elevated if the patient had a previous history of papillary or follicular cancer, and calcitonin is dramatically elevated in patients with prior histories of medullary carcinoma. In patients with hyperparathyroidism secondary to a parathyroid adenoma, the adenoma can be ablated under ultrasound guidance using 95% alcohol. Depending on the size of the parathyroid adenoma, a small (1-2 mL) volume of absolute ethanol is injected into the gland under sonographic visualization.

In addition treatment upper respiratory infection amoxicillin 500 mg buy cheap, drugs that block b-adrenergic receptors are used to reduce the arterial pressure in people with hypertension medicine hat tigers order amoxicillin cheap. They reduce myocardial work and cardiac output by inhibiting the effect of sympathetic neurons on heart rate and contractility medicine daughter lyrics purchase amoxicillin now. Drugs that prevent or reverse clotting within hours of its occurrence are also extremely important in the treatment (and prevention) of heart attacks medicine wheel wyoming buy 500 mg amoxicillin with visa. Use of these drugs medications you can crush order 500 mg amoxicillin otc, including aspirin, will be described in Section F of this chapter. Finally, a variety of drugs decrease plasma cholesterol by influencing one or more metabolic pathways for cholesterol (Chapter 16). There are several interventions for coronary artery disease after cardiac angiography (described earlier in this chapter) identifies an area of narrowing or occlusion. This procedure enlarges the lumen by stretching the vessel and breaking up abnormal tissue deposits. Stents are tubes made of a stainless steel lattice that provide a scaffold within a vessel to open it and keep it open. Researchers are testing stents made of a hardened, biodegradable polymer that is absorbed after 6 months to 1 year. Another surgical treatment is coronary bypass, in which a new vessel is attached across an area of occluded coronary artery. Despite the widespread use of these surgical interventions and their proven effectiveness in relieving the pain of angina, evidence accumulated over the past 20 years suggests that such procedures have a limited effect on long-term survival after a cardiac event or on the prevention of future events. Many arteries of the body are subject to this same occluding process, and wherever the atherosclerosis becomes severe, the resulting symptoms reflect the decrease in blood flow to the specific area. For example, occlusion of a cerebral artery due to atherosclerosis and its associated blood clotting can cause a stroke. Finally, note that both myocardial infarcts and strokes due to occlusion may result when a fragment of blood clot or fatty deposit breaks off and then lodges elsewhere, completely blocking a smaller vessel. The increase in cardiac output depends not only on the autonomic influences on the heart but on factors that help increase venous return. Hypertension is usually due to increased total peripheral resistance resulting from increased arteriolar vasoconstriction. More than 90% of cases of hypertension are called primary hypertension, meaning that a specific cause of the increased arteriolar vasoconstriction is unknown. However, obesity, excessive salt intake, and a variety of other environmental factors clearly contribute to the development of hypertension. Heart failure can occur as a result of diastolic or systolic dysfunction; in both cases, cardiac output becomes inadequate. This leads to fluid retention by the kidneys and formation of edema because of increased capillary pressure. Hypertrophic cardiomyopathy is a disease caused by genetic mutations in genes coding for cardiac contractile proteins. It results in thickening of the left ventricle wall and septum, and disruption of the orderly array of myocytes and conducting cells. If not successfully treated, it can result in sudden death by arrhythmia or heart failure. Hypotension can be caused by loss of body fluids, by cardiac malfunction, by strong emotion, and by liberation of vasodilator chemicals. Shock is any situation in which blood flow to the tissues is low enough to cause damage to them. The major cause of reduced coronary blood flow is atherosclerosis, an occlusive disease of the arteries. People may suffer intermittent attacks of angina pectoris without actually suffering a heart attack at the time of the pain. Atherosclerosis can also cause strokes and symptoms of inadequate blood flow in other areas. Coronary artery disease incidence is reduced by exercise, good nutrition, and avoiding smoking. Treatments for coronary artery disease include drugs that dilate blood vessels, reduce blood pressure, and prevent blood clotting. In the upright posture, gravity acting upon unbroken columns of blood reduces venous return by increasing vascular pressures in the veins and capillaries in the limbs. The increased venous pressure distends the veins, causing venous pooling, and the increased capillary pressure causes increased filtration out of the capillaries. The changes are due to active hyperemia in the exercising skeletal muscles and heart; increased sympathetic outflow to 1. What happens to plasma volume and interstitial fluid volume following a hemorrhage? List the directional changes that occur during exercise for all relevant cardiovascular variables. What changes in cardiac function occur at rest and during exercise as a result of endurance training? Blood was defined earlier as a mixture of cellular components suspended in a fluid called plasma. In this section, we will take a more detailed look at blood cells and plasma and then discuss the complex mechanisms that prevent excessive blood loss following injury. When a pluripotent stem cell divides, its two daughter cells either remain pluripotent stem cells or become committed to a particular developmental pathway. The first branching yields either lymphoid stem cells, which give rise to the lymphocytes, or myeloid stem cells, the progenitors of all the other varieties. At some point, the proliferating offspring of the myeloid stem cells become committed to differentiating along only one path - for example, into erythrocytes. A list of the major substances dissolved in plasma and their typical concentrations can be found inside the back cover of this book. Their role in exerting an osmotic pressure that favors the absorption of extracellular fluid into capillaries was described in Section C of this chapter. They can be classified into three broad groups: the albumins, the globulins, and fibrinogen. The first two have many overlapping functions, which are discussed in relevant sections throughout the book. The albumins are the most abundant of the three plasma protein groups and are synthesized by the liver. Fibrinogen functions in clotting, discussed in detail in the latter part of this section. Cells normally do not take up plasma proteins; plasma proteins perform their functions in the plasma itself or in the interstitial fluid. In addition 428 Chapter 12 Erythrocytes the major function of erythrocytes is gas transport; they carry oxygen taken in by the lungs and carbon dioxide produced by the cells. Erythrocytes contain large amounts of the protein hemoglobin with which oxygen and, to a lesser extent, carbon dioxide reversibly combine. For simplicity, no attempt has been made to differentiate the appearance of the various precursors. Erythrocytes are an excellent example of the general principle of physiology that structure is a determinant of - and has coevolved with - function. This shape and their small size (7 mm in diameter) impart to the erythrocytes a high surface-area-to-volume ratio, so that oxygen and carbon dioxide can diffuse rapidly to and from the interior of the cell. The site of erythrocyte production is the soft interior of certain bones called bone marrow, specifically, the red bone marrow. With differentiation, the erythrocyte precursors produce hemoglobin, but then they ultimately lose their nuclei and organelles - their machinery for protein synthesis. Young erythrocytes in the bone marrow still contain a few ribosomes, which produce a weblike (reticular) appearance when treated with special stains, an appearance that gives these young erythrocytes the name reticulocyte. Normally, erythrocytes lose these ribosomes about a day after leaving the bone marrow, so reticulocytes constitute only about 1% of circulating erythrocytes. In the presence of unusually rapid erythrocyte production, however, many more reticulocytes can be found in the blood, a phenomenon of clinically diagnostic usefulness. Because erythrocytes lack nuclei and most organelles, they can neither reproduce themselves nor maintain their normal structure for very long. The average life span of an erythrocyte is approximately 120 days, which means that almost 1% of the erythrocytes are destroyed and must be replaced every day. Destruction of damaged or dying erythrocytes normally occurs in the spleen and the liver. The major breakdown product of hemoglobin is bilirubin, which is returned to the circulation and gives plasma its characteristic yellowish color (Chapter 15 will describe the fate of this substance). Iron As noted previously, iron is the element to which oxygen binds on a hemoglobin molecule within an erythrocyte. Small amounts of iron are lost from the body via the urine, feces, sweat, and cells sloughed from the skin. In order to remain in iron balance, the amount of iron lost from the body must be replaced by ingestion of iron-containing foods. Particularly rich sources of iron are meat, liver, shellfish, egg yolk, beans, nuts, and cereals. A significant disruption of iron balance can result in either iron deficiency, leading to inadequate hemoglobin production, or an excess of iron in the body (hemochromatosis), which results in abnormal iron deposits and damage in various organs, including the liver, heart, pituitary gland, pancreas, and joints. The homeostatic control of iron balance resides primarily in the intestinal epithelium, which actively absorbs iron from ingested foods. The body has a considerable store of iron, mainly in the liver, bound up in a protein called ferritin. About 50% of the total body iron is in hemoglobin, 25% is in other heme-containing proteins (mainly the cytochromes) in the cells of the body, and 25% is in liver ferritin. As old erythrocytes are destroyed in the spleen (and liver), their iron is released into the plasma and bound to an iron-transport plasma protein called transferrin. Transferrin delivers almost all of this iron to the bone marrow to be incorporated into new erythrocytes. Recirculation of erythrocyte iron is very important because it involves 20 times more iron per day than the body absorbs and excretes. Folic Acid and Vitamin B12 Folic acid, a vitamin found in large amounts in leafy plants, yeast, and liver, is required for synthesis of the nucleotide base thymine. When this vitamin is not present in adequate amounts, impairment of cell division occurs throughout the body but is most striking in rapidly proliferating cells, including erythrocyte precursors. The production of normal erythrocyte numbers also requires extremely small quantities (one-millionth of a gram per day) of a cobalt-containing molecule, vitamin B12 (also called cobalamin), because this vitamin is required for the action of folic acid. Vitamin B12 is found only in animal products, and strictly vegetarian diets tend to be deficient in it. Also, the absorption of vitamin B12 from the gastrointestinal tract requires a protein called intrinsic factor, which is secreted by the stomach (see Chapter 15). Lack of this protein, therefore, causes vitamin B12 deficiency, and the resulting erythrocyte deficiency is known as pernicious anemia. In the previous section, we stated that iron, folic acid, and vitamin B12 must be present for normal erythrocyte Bone production, or erythropoiesis. However, none marrow Spleen of these substances constitutes the signal that (and liver) regulates the production rate. The direct control of erythropoiesis is All other cells exerted primarily by a hormone called erythropoietin, which is secreted into the blood mainly by a particular group of hormonesecreting connective tissue cells in the kidneys. Erythropoietin acts on the bone marrow Iron recirculation to stimulate the proliferation of erythrocyte progenitor cells and their differentiation into Plasma iron mature erythrocytes. The erythropoietin Loss (urine, skin cells, sweat, menstrual Dietary absorption secretion rate is increased markedly above basal blood) values when there is a decreased oxygen delivery to the kidneys. Situations in which this occurs include insufficient pumping of blood by the heart, lung disease, anemia (a decrease in number of erythrocytes or in hemoglobin concentration), prolonged exercise, and exposure to high altitude. As a result of the increase in erythropoietin secretion, plasma erythropoietin concentration, erythrocyte production, Storage (mainly in liver) and the oxygen-carrying capacity of the blood all increase. The thickness of the the male sex hormone, also stimulates the release of erytharrows correlates with the amount of iron involved. This accounts in part for the higher hematocrit in state, the rate of gastrointestinal iron absorption equals the rate of men than in women. The cell at left assumed this sickle shape after exposure to lowoxygen conditions. Sickle-cell disease is an example of a disease that is manifested fully only in people homozygous for the mutated gene (that is, they have two copies of the mutated gene, one from each parent). In heterozygotes (one mutated copy and one normal gene), people who are said to have sicklecell trait, the normal gene codes for normal hemoglobin and the mutated gene for the abnormal hemoglobin. The erythrocytes in this case contain both types of hemoglobin, but symptoms are observed only when the oxygen level is unusually low, as at high altitude. The persistence of the sickle-cell mutation in humans is due to the fact that heterozygotes are more resistant to malaria, a blood infection caused by a protozoan parasite that is spread by mosquitoes in tropical regions. Finally, there also exist conditions in which there are more erythrocytes than normal, a condition called polycythemia. An example, to be described in Chapter 13, is the polycythemia that occurs in high-altitude dwellers. In this case, the increased number of erythrocytes is an adaptive response because it increases the oxygen-carrying capacity of blood exposed to low oxygen levels. As discussed earlier, however, increasing the hematocrit increases the viscosity of blood. Therefore, polycythemia makes the flow of blood through blood vessels more difficult and puts a strain on the heart. Abuse of synthetic erythropoietin and the subsequent extreme polycythemia have resulted in the deaths of competitive bicyclists - one reason that such "blood doping" is banned in sports. Anemia As just described, anemia is defined as a decrease in the ability of the blood to carry oxygen due to (1) a decrease in the total number of erythrocytes, each having a normal quantity of hemoglobin; (2) a diminished concentration of hemoglobin per erythrocyte; or (3) a combination of both. Sickle-cell disease (formerly called sickle-cell anemia) is due to a genetic mutation that alters one amino acid in the hemoglobin chain. The leukocytes are all involved in immune defenses and Cardiovascular Physiology 431 include neutrophils, eosinophils, monocytes, macrophages, basophils, and lymphocytes.

Abnormal digital arteries are often found in smokers medicine 20th century generic amoxicillin 250 mg without a prescription, patients with renal failure medicine buddha mantra amoxicillin 250 mg overnight delivery, diabetics medicine on airplanes order amoxicillin 500 mg mastercard, and individuals who perform heavy manual work treatment brown recluse bite buy amoxicillin with mastercard. The subclavian artery origins are difficult to visualize with ultrasound symptoms diverticulitis amoxicillin 500 mg order, but abnormal waveforms and flow velocities in accessible portions of the vessel infer a proximal lesion. Alternatively, bypass from a more accessible inflow source such as either common carotid artery or the contralateral axillary artery is less rigorous for the patient and usually performed if the anatomy permits. Thoracic sympathectomy may delay or prevent amputation in patients with intractable digital ischemia due to fixed occlusive disease. Gadolinium-enhanced three-dimensional magnetic reso- nance angiogram viewed in the left anterior oblique projection showing a focal proximal left subclavian artery stenosis (arrow). Late image from gadolinium-enhanced time-resolved contrast imaging magnetic resonance angiogram of the hand in a patient with second digit ischemia due to a small embolus. The image spatial resolution is not sufficient to permit evaluation of the peripheral digital arteries, and there is venous filling on this late image, but the abnormal perfusion of the second digit is evident. The muscle mass of the upper body is smaller than in the lower limbs and is used less vigorously (perhaps if we walked on all fours symptomatic upper extremity arterial disease would be more common). Causes of Chronic Upper Extremity Raynaud syndrome/disease Atherosclerosis Connective tissue disease Vibration injury Buerger disease Hypercoagulable syndromes Frostbite Chronic renal failure Diabetes Recurrent embolization Acrocyanosis innominate arteries. Careful stent positioning is required in this location to avoid compression of the orifice of the common carotid artery on the right or protruding too far into the aorta on the left. However, stents should be avoided in the segment of the subclavian artery between the clavicle and the first rib, because they can be crushed by the bony structures. The technical success rate of subclavian and innominate artery angioplasty and stent placement is greater than 95%, with a complication rate (stroke and distal embolization) of less than 1%. There is relatively little information on the long-term patency of these procedures, but available results suggest excellent outcomes. Causes of Chronic Upper Extremity Ischemia: Large Vessel Atherosclerosis Trauma Recurrent embolization Thoracic outlet syndrome Steal (dialysis fistula or graft) Vasculitis · Giant cell arteritis · Takayasu arteritis · Radiation arteritis · Buerger disease Fibromuscular dysplasia Acute upper extremity ischemia usually presents with digital and hand symptoms. Mild ischemia may result in simply a cold finger or hand with delayed capillary refill, whereas severe ischemia produces a cadaveric extremity. When a patient presents with ischemia localized to the fingers, the distribution of affected fingers suggests the arteries involved (first and second digits, radial artery; third, radial or ulnar arteries; fourth and fifth, ulnar artery). These patients report acute onset of severe symptoms in association with a known or newly discovered cardiac arrhythmia or structural abnormality. Recurrent emboli in the same arm implicate a source within that extremity, such as a subclavian aneurysm (see Thoracic Outlet Syndrome). Other etiologies are trauma (including iatrogenic), aortic dissection, thrombosis of an existing lesion, severe vasospasm, and in situ thrombosis due to a hypercoagulable syndrome. Patients at risk are older diabetics and smokers with preexisting but asymptomatic occlusive disease of the forearm and digital arteries. The relationship of the stenosis to the origin of cerebral branches and the status of the other cerebral arteries are key considerations when planning the procedure. Occlusion of a vertebral artery origin by a dissection flap during subclavian artery angioplasty, although rare, could result in a stroke in a patient with poor intracranial collateral circulation. B, Digital subtraction angiogram of the hand, with warming, shows occlusion of the ulnar artery and diffuse small artery occlusive disease involving all of the digits. Sources of Upper Extremity Emboli Heart · Left ventricle · Left atrium · Aortic valve Upper extremity artery aneurysm (subclavian, axillary, ulnar) Atherosclerotic plaque Ascending aortic aneurysm Subclavian and axillary artery fibromuscular dysplasia Iatrogenic · Dialysis access declotting · Cardiac surgery Paradoxical a pressure drop distal to the fistula and even reversal of flow in the distal radial artery (after a Brescia Cimino fistula) can result in neurologic injury, pain, and eventually ulceration and even gangrene. When patients present with acute upper extremity ischemia, physical examination and history alone may be sufficient to plan management. For example, a patient with acute hand ischemia, a bounding pulse that terminates abruptly in the antecubital brachial artery, and an arrhythmia likely has a brachial artery embolus and should proceed to embolectomy (Table 6-3). The findings of a focal aneurysm or occlusion of the ulnar artery in the base of the hand is suggestive of hypothenar hammer syndrome (see Trauma). In these cases, proximal surgical thromboembolectomy can be combined with intraoperative local distal injection of a thrombolytic agent. Percutaneous intervention for acute upper extremity ischemia is performed less often than for lower extremity acute ischemia because the condition is not as common and the neighboring vascular bed at risk (the central nervous system) is less forgiving. Thrombolysis, either pharmacologic, pharmacomechanical, or mechanical may be helpful when extensive thrombus is present, particularly in the small vessels of the hand. For very distal thrombosis, good results with thrombolysis are frequently obtained with the catheter positioned in the distal brachial artery to perfuse the entire forearm and hand. When a femoral artery approach is used, anticoagulation with heparin is important to prevent pericatheter thrombus formation in the subclavian artery and subsequent vertebral artery embolization. Published experience with upper extremity thrombolysis suggests that overall results are promising with few complications in properly selected patients. Stenting the subclavian artery between the clavicle and first rib should be avoided (unless the first rib has been removed) because the repeated external compression in this location will fracture any stent. Banding of the fistula or revision of the arterial anastomosis can decrease the degree of shunting while preserving dialysis access. Occasionally, coil occlusion of the radial artery distal to the arterial anastomosis of a Brescia-Cimino (radial artery to cephalic vein at the wrist) fistula is used to eliminate steal from the fingers through the palmar arches. Patients may present with hand numbness, tingling, or coolness with activities that require arm abduction, and diminished extremity pulses. Acute embolic events to the forearm and hand occur in up to 40% of patients (due to clot formation in poststenotic subclavian artery aneurysms), and may be the initial presenting symptom. Several evocative maneuvers have been advocated for detection of arterial thoracic outlet syndrome, such as the Adson maneuver (caudal traction on the arm, head turned toward the arm, and inspiration) and 90-degree abduction and external rotation. However, compression of the subclavian artery resulting in diminished distal pulses is very common (at least 50%) in normal subjects (try it on yourself). There are three locations at which thoracic outlet syndrome can occur: the scalene triangle, the costoclavicular space, and bilateral upper extremity paradoxical emboli. The most common site of arterial compression is the scalene triangle (often associated with an anomalous or accessory rib), followed by the costoclavicular space. The goals of angiography in these patients are to evaluate the subclavian artery for stenosis, aneurysmal change, the presence of thrombus, and to detect distal emboli. Injections with the arm in neutral position, and one with the arm in a position that elicits symptoms, have been considered essential in the past. Definitive therapy requires surgical decompression of the thoracic outlet, resection of the aneurysm, and placement of a bypass graft. Exclusion of the aneurysm can also be accomplished with a stent-graft, but prior decompression of the extrinsic structures is necessary. There has been only slight improvement in the hand, because most of the occlusions are chronic (arrowhead on palmar digital artery showing intraluminal webs consistent with chronic thrombosis). There are numerous etiologies of upper extremity aneurysms, several of which are discussed in other sections of this chapter (Box 6-6). These aneurysms are associated with atherosclerosis and aortic, contralateral subclavian, or visceral artery aneurysms in up to 50% of patients. Ulcerated plaque in the axillary artery causing acute and chronic digital artery atheroembolization in a 58-year-old woman with vascu- lopathy presenting with finger gangrene, ulcerations, and superimposed acute digital ischemia. B, the stenosis was treated with primary stent placement (arrow) using a selfexpanding nitinol stent (8 mm Ч 20 mm), followed by angioplasty to 7 mm. In 80% of patients, the aberrant subclavian artery lies posterior to the esophagus, in 15% between the esophagus and trachea, and anterior to both in 5%. Although extremely rare, the same pathology can be found in an aberrant left subclavian artery in patients with right-sided aortic arches. Etiologies of intrathoracic subclavian aneurysms other than degeneration should be carefully excluded, particularly trauma and chronic dissection. Angiography may not be necessary unless the relationship of the aneurysm to cerebral artery origins or the aorta cannot be determined. Patients may present with intermittent or fixed ischemic symptoms, ranging from diminished upper extremity pulses to digital ulceration. When there is digital involvement, angiography is necessary to differentiate between embolic, atherosclerotic, and inflammatory diseases. The location of the vascular abnormality is somewhat helpful in classifying the vasculitis, although in this situation the destiny of all rules (to be broken) is often fulfilled. In general there are multiple occlusions of the medium to small arteries of the hand, particularly in the digits, with poor collateralization. The brachial artery has been ligated distal to the fistula (arrowhead), and a vein bypass (arrow) placed from the proximal to distal brachial artery around the fistula. Coronal reformat of a three-dimensional gadolinium- enhanced magnetic resonance angiogram showing an aneurysm of the distal subclavian and axillary arteries in a woman who presented with a cervical rib and pulsatile supraclavicular mass. Central (intrathoracic) aneurysms can present with pain, compression of adjacent structures such as veins and nerves (including hoarseness when the right recurrent laryngeal nerve is involved), distal thromboembolism, and rupture. A, Three-dimensional surface rendering from a chest computed tomography scan shows a hypoplastic first right rib (arrow), which articulates with an exostosis (arrowhead) arising from a hypertrophied second rib. B, Sagittal reconstruction shows the subclavian artery (open arrow) compressed between the clavicle (white arrow) and the exostosis (arrowhead). In the absence of hard clinical signs, a major vascular injury is unlikely, and patients are managed conservatively with observation and clinical follow-up. Shotgun wounds are an exception, in that the large area of soft tissue trauma and the multiple pellets makes physical examination difficult and less reliable. Penetrating injury to the chest in the vicinity of the intrathoracic portions of subclavian artery (zone 1, see Table 5-4) is also considered differently, in that physical examination of these vessels is impossible, and surgical repair requires a thoracotomy. This occurs when there is sudden extreme traction on the arm, such as when trying to stop a fall from a tree by grabbing a branch, or dislocation. Concomitant neurologic injury occurs in over 40% of traction injuries to the arm owing to avulsion of the brachial plexus nerve roots. Iatrogenic injuries to the upper extremity arteries occur most often during central venous access procedures or placement of an arterial line for hemodynamic monitoring. Care in interpretation of this result in the absence of a subclavian artery aneurysm is necessary because this same finding can be induced in asymptomatic individuals. Ruptured aneurysm of aberrant right subclavian artery in a 49-year-old hypertensive woman presenting with acute chest pain and tran- Box 6-7. Vasculitides Affecting the Upper Extremities Digital · Systemic lupus erythematosus · Scleroderma · Rheumatoid · Buerger disease · Polyarteritis nodosa Forearm · Buerger disease Axillary artery · Giant cell · Systemic lupus erythematosus (rare) Subclavian artery · Takayasu arteritis · Behзet disease Box 6-8. Subtracted angiogram showing intimal irregularity (arrow) and intraluminal thrombosis (open arrow) of the subclavian and axillary arteries in a patient who had diminished right upper extremity pulses and a brachial plexus injury after falling from a tree. Note that the coils were placed from distal to proximal across the injury to prevent retrograde perfusion from intercostals and inferior epigastric arteries. An underlying intrinsic abnormality of the ulnar artery, such as fibromuscular dysplasia, has been proposed as a contributing factor. Symptoms occur when the aneurysms or intimal irregularities thrombose or become a source of digital emboli, characteristically to the third through fifth fingers. Angiography remains the best imaging modality for this entity, although ultrasound may be used to determine the size of the aneurysm. Self-administered drugs injected directly into an upper extremity artery can result in pseudoaneurysms, arteriovenous fistulas, dissections, and thrombosis. The brachial artery can be injured by blunt trauma to the inside of the upper arm such as might occur with chronic improper use of crutches. Results of a multidisciplinary strategy for management of mediastinal parathyroid adenoma as a cause of persistent primary hyperparathyroidism. Positional compression of the axillary artery causing upper extremity thrombosis and embolism in the elite overhead throwing athlete. Those that continue to manifest primary hyperparathyroidism should undergo angiography followed by venous sampling (discussed in Chapter 7). Wedged injection of hypertonic contrast or absolute alcohol into a parathyroid adenoma results in cure in 60%-70% of patients, but most reoccur within 5 years. Percutaneous angioplasty and stenting of left subclavian artery stenosis in patients with left internal mammary-coronary bypass grafts: clinical experience and long-term follow-up. The upper extremity veins are of critical importance for dialysis patients, whether they are managed with venous catheters or surgically created access. These valveless veins begin at the sigmoid fossa of the skull and anastomose with the subclavian veins at the base of the neck, behind the proximal head of the clavicle. Superficial in location, these veins are frequently visible as they pass over the upper sternocleidomastoid muscle and travel in an oblique course Veins of the Upper Extremities the veins of the upper extremities are divided into superficial and deep systems. At the antecubital fossa just below the elbow joint, the cephalic vein sends a branch, the median cubital vein, obliquely across to join the basilic vein, which swings anteriorly in the upper third of the forearm to meet this branch. At the shoulder, the cephalic vein passes between the pectoralis and deltoid muscles, diving over the medial edge of the pectoralis minor muscle to join the deeper axillary vein. The basilic vein ascends along the 136 Upper extremity, Neck, aNd ceNtral thoracic VeiNs 137 medial border of the biceps muscle, superficial to the brachial fascia, accompanied by only a few small superficial nerves. At the junction of the distal and middle thirds of the upper arm, the basilic vein pierces the brachial fascia to join the deep (brachial) veins. Occlusion of an axillary or subclavian vein results in collateral flow through muscular and superficial veins about the shoulder, scapula, and chest wall. Central Thoracic Veins Blood from the upper extremities and the head returns to the heart through the brachiocephalic (or innominate) veins and the Cephalic vein Axillary vein Basilic vein Brachial veins B Radial veins Key Collateral Pathways Deep palmar arch Interosseous veins Ulnar veins Superficial palmar arch the venous drainage of the upper extremities is rich with potential collateral pathways. The left brachiocephalic vein, fully 2-3 times longer than the right, crosses from the left side of the mediastinum anterior to the great vessels to join the right brachiocephalic vein. Important tributaries of the brachiocephalic vein include the internal mammary, vertebral, pericardiophrenic, and the first intercostal veins. The azygos vein ascends anterior to the thoracic spine to the right of the midline, while the hemiazygos vein lies slightly to the left of the midline anterior to the spine. The accessory hemiazygos vein is a small, left-sided tributary of either the azygos or hemiazygos vein that drains the upper (through T8) intercostal veins.

Once the wire is deep in the portal system keratin treatment buy amoxicillin on line amex, the tapered black outer guide for needle or cannula can then be advanced over the wire into the portal vein medicine cabinets surface mount amoxicillin 250 mg buy amex. In an awake patient 88 treatment essence cheap 250 mg amoxicillin free shipping, this usually hurts more than the puncture medicine keppra buy generic amoxicillin online, but provides maximum security when exchanging for a pigtail catheter treatment models order 250 mg amoxicillin mastercard. The delivery catheter is then retracted until the bare metal stent rings are pulled tight against, but not into, the parenchymal tract. A venogram is performed with a pigtail catheter to document positioning, and the final pressure gradient across the shunt is determined. Pressure measurements are then obtained so that the opening gradient can be documented, followed by a portogram (preferably with the catheter in the splenic vein to confirm its patency). This is the most uncomfortable part of the procedure so it is helpful to alert the anesthesiologist or administer additional analgesics to the awake patient before inflating the balloon. A noncompliant balloon, 6-8 mm in diameter and 4-6 cm in length is positioned across the transhepatic tract and the sheath is withdrawn. These identify the length and location of the transhepatic tract, in that they represent the more resilient fibrous tissue surrounding the portal and hepatic veins. Combined arterial and bile duct injury during needle passes can lead to a fistula and significant hemobilia and/or biliary obstruction. Careless manipulation of instruments in the right atrium can induce cardiac arrhythmias or perforate the atrium, causing cardiac tamponade. A transient (weeks to months) hemolytic anemia has been described in approximately 10% of patients with bare stents, possibly due to fracture of red blood cells in the stent. Causes of procedural failure include inability to access a hepatic or portal vein, hard liver parenchyma that prevents puncture with the needle, and occluded portal veins. Initial clinical success varies with the indication; for recurrent variceal bleeding it is approximately 98% (range 97%-100%), whereas for intractable ascites approximately 60%-70% of patients respond. External restricting balloon-expandable stent used to control expansion of the 10-mm diameter self-expanding stent-graft in a patient at increased risk of encephalopathy after transjugular intrahepatic portosystemic shunt for ascites. The stent-graft was dilated to 8 mm to obtain the desired final gradient, and the external stent will ensure that it remains at that diameter unless enlarged with an angioplasty balloon. The broad applicability of these results is uncertain, in that the majority of the patients consumed alcohol up to the time of treatment and the overall prevalence of chronic viral hepatitis was low (16%). This approach is very useful for patients with difficult hepatic or portal vein anatomy, hepatic parenchymal lesions that would obstruct a standard approach, or very small livers in whom extracapsular puncture is a concern. Catheterization of these collaterals from the left renal vein with an occlusion balloon and temporary obstruction of outflow allows retrograde injection of a sufficient volume of sclerosing agent to fill the gastric varices. Contrast is injected through the occlusion balloon with sufficient volume to fill the gastric varices almost to the splenic and/or coronary vein. The sclerosing agent can be injected through the balloon catheter or ideally a high-flow microcatheter advanced as deep within the varices as possible. The sclerosing agent is injected under fluoroscopic control until the gastric varices are completely filled or reflux is seen into a nontarget vein. The balloon remains inflated for at least 4 hours (some operators leave the balloon in overnight) to maximize exposure of the varices to the sclerosant. Alternatively, patients with Viatorr endografts can be managed expectantly with observation for either recurrent varices (with endoscopy) or ascites (physical exam). The stent-graft can be seen extending a few millimeters beyond the orifice of the right hepatic vein into the inferior vena cava (bent arrow). The indications are primarily thrombocytopenia, although encephalopathy and liver function have been reported to improve post­partial splenic embolization, and risk of variceal bleeding decreases when combined with endoscopic ligation. Patients with acute thrombotic occlusions are usually hypercoagulable (>80% have at least one risk factor, and 50% have two or more), either from an underlying coagulation disorder, pregnancy, oral contraceptive use, or a malignancy (Box 14-11). Patients with chronic Budd-Chiari syndrome may have hypertrophy of the caudate and atrophy of the right lobes of the liver, and gastroesophageal varices. Acute major complications occur in fewer than 5% and include thrombosis of the portal vein, pulmonary embolism from dislodged clot, and renal failure from extensive hemolysis. Predictably, other varices (usually esophageal) develop or progress in two thirds of patients since the underlying portal hypertension remains uncorrected. B, Digital image obtained after inflation of an occlusion balloon (arrow) in the inferior phrenic vein proximal to the left adrenal vein and retrograde injection of sclerosant opacified with contrast through a microcatheter several centimeters above the balloon. C, Digital image obtained about 30 minutes later shows penetration of the sclerosant deep into the left gastric varices almost to the splenic vein. Budd-Chiari Syndrome: Levels of Hepatic Hepatic venules Main hepatic veins Hepatic vein orifices Suprahepatic inferior vena cava Syndrome Box 14-10. The standard management for patients with acute Budd-Chiari syndrome is anticoagulation and identification of prothrombotic risk factors. The wedged hepatic venogram, if it can be performed, usually does not show the portal vein because the level of obstruction is postsinusoidal. In comparison to patients with alcoholic or viral cirrhosis, the liver in Budd-Chiari syndrome is often enlarged, which requires longer needle passes and often multiple stentgrafts. The clinical presentation and management are different for these two groups, with cirrhotic patients usually more symptomatic from their liver disease, and patients without cirrhosis symptomatic from the acute venous occlusion. A, Contrast-enhanced computed tomography scan showing patchy enhancement of the liver parenchyma with the exception of a hypertrophied caudate lobe (arrow). Isolated acute portal vein thrombosis in noncirrhotic patients presents with acute onset of upper abdominal pain with nonacute abdominal physical examination, fever, ascites, and abnormal liver enzymes. Severely symptomatic patients (ascites, abdominal pain, hepatic dysfunction) with acute thrombosis of the portal vein may benefit from endovascular recanalization of the portal vein using catheter-directed thrombolysis, mechanical thrombectomy, and/or stent placement. Chronic portal vein thrombosis typically leads to an extensive system of dilated collateral channels in the gastrohepatic ligament and porta hepatis. When cirrhosis is present, the formation of portal-tosystemic collaterals, notably gastroesophageal varices, can subsequently bleed. Portal Vein Thrombosis Portal vein thrombosis occurs in patients with uncompensated cirrhosis, malignancy, and hypercoagulable disorders. Percutaneous catheter-based treatment is not common for acute splenic vein occlusion because the spleen has well-established collateral drainage. The incomplete opacification of the bare stent in the portal vein is due to unopacified inflow from the superior mesenteric vein (bent arrow). In stable patients without peritoneal signs, anticoagulation is the first line of therapy with almost three fourths of patients achieving at least partial clearing of the thrombus. When patients have ongoing pain, bowel wall thickening, or other signs suggestive of progressive venous congestion, catheter-directed thrombolysis using direct transhepatic access successfully restores patency. Early image from a selective hepatic artery digital subtraction angiogram shows a hypervascular mass invading the middle hepatic vein and extending into the inferior vena cava (arrows) with associated arteriovenous shunting. Intimal hyperplasia related to the anastomosis can result in late portal vein stenosis, which presents as presinusoidal extrahepatic portal hypertension. Hepatic arteriography or percutaneous image-guided biopsy may be needed to make the distinction between bland thrombus and tumor thrombus in problem cases. Carcinoid tumor is a member of the neuroendocrine group of tumors and occurs most frequently in the right lower quadrant, either in the appendix or the terminal ileum. Neoplastic enlargement of lymph nodes in the gastrohepatic ligament and porta hepatis can also lead to obstruction of the main portal vein. The morbidity and mortality (related to hepatic insufficiency) after partial hepatectomy are decreased in patients who have undergone portal vein embolization before resection. The estimated minimal residual volume of liver required to tolerate extended partial hepatectomy depends on the health of the liver, with greater volumes necessary in patients with underlying parenchymal disease (40%) or prior chemotherapy (30%) compared to those with a normal liver (20%). This method, which is often referred to as the standardized estimate, accommodates for the different liver volumes required by different sized patients. Transhepatic percutaneous access through one of the segments that will ultimately be removed reduces the risk of damage to the portion of liver that will be preserved. Ultrasound guidance allows access of a peripheral portal vein segment, followed by placement of a 5-French sheath with a radiopaque marker band. The entire portion of liver to be removed should be embolized, because hypertrophy of segments of the liver intended for resection has no clinical benefit and may decrease the amount of hypertrophy in the planned liver remnant. The goal is peripheral occlusion, so when particles are used, the size should be 100-200, followed by coils in the larger segmental arteries. At the end of the procedure, coils are placed in the portal branch, through which access was obtained (if ipsilateral to the embolization), and coils or gelatin sponges are used to occlude the parenchymal tract. The overall complication rate is about 2%-9%, including portal vein thrombosis, hemoperitoneum, subcapsular hematoma, pseudoaneurysm, and hemobilia. Many of the complications are related to the transhepatic access, prompting some interventionalists to prefer the ipsilateral transhepatic puncture. The average volume increase achieved with extensive right lobe embolization depends on the presence or absence of preexisting liver disease and whether or not segment 4 embolization is included. The biopsy needle is then advanced a few millimeters into the hepatic parenchyma and the spring-loaded mechanism is fired, deploying the cutting needle and obtaining the biopsy. An assistant should carefully hold the guiding cannula in the hepatic vein while the sample is retrieved from the biopsy device because respiratory motion tends to displace the system from the hepatic vein. Transjugular liver biopsy with a cutting needle is successful in obtaining hepatic tissue in at least 98% of cases and, in contrast to older transvenous techniques, yields samples of high diagnostic quality. This procedure may also be performed in absence of coagulopathy or ascites when wedged hepatic vein pressures are needed in addition to a biopsy for initial workup of cirrhosis. The amount of ascites sufficient to exclude the percutaneous route is less well defined, but any volume of ascites that displaces the liver from the abdominal wall is of concern. The rationale for the transjugular technique is simple; jugular venous access can be safely obtained in the presence of coagulopathy, particularly with ultrasound guidance, and the biopsy needle never transgresses the liver capsule, thus eliminating the risk of intraperitoneal bleeding. Long-term results of balloonoccluded retrograde transvenous obliteration for gastric variceal bleeding and risky gastric varices: a 10-year experience. Multidetector-row computed tomography in the evaluation of transjugular intrahepatic portosystemic shunt performed with expanded-polytetrafluoroethylene-covered stent-graft. Advanced hemodynamic monitoring before and after transjugular intrahepatic portosystemic shunt: implications for selection of patients­a prospective study. Transjugular intrahepatic portosystemic shunts: adjunctive embolotherapy of gastroesophageal collateral vessels in the prevention of variceal rebleeding. Transjugular portosystemic shunt in chronic portal vein occlusion: importance of segmental portal hypertension in cavernous transformation of the portal vein. Advanced disease frequently results in limb loss, although often the underlying systemic disease has the greatest impact on mortality. However, in the presence of occlusion of the runoff vessels, the musculoskeletal branches become the principal source of collateral blood supply. In addition to containing the artery, the sheath also contains the femoral vein (medial to the artery) and the femoral canal (the most medial structure). The femoral nerve lies lateral to the femoral sheath, within the femoral triangle formed by the sartorius muscle laterally, the adductor longus muscle medially, the inguinal ligament superiorly, and the iliacus, psoas major, pectineus, and adductor longus muscles posteriorly. Although these are not official anatomic terms, the popliteal artery should always be described in this manner because the type of intervention and subsequent outcome are influenced by the level of disease. The posterior calf muscles are supplied by the vertically oriented sural arteries arising from the posterior aspect of the popliteal artery. The calcified and occluded superficial femoral artery (white arrow) lies beneath the sartorius muscle (arrowhead), slightly anterior and medial to the femoral vein (open arrow). Computed tomography angiogram of the pelvis showing high bifurcation of the left common femoral artery (arrow) anterior to the femoral head. In most instances, the tibioperoneal trunk is a short artery of variable length that descends several centimeters beyond the anterior tibial artery origin before bifurcating into the posterior tibial and peroneal arteries. Coronal maximum intensity projection of a three- dimensional gadolinium-enhanced magnetic resonance angiogram at the level of the knees, showing high origin of the right anterior tibial artery (arrow) and low origin of the right posterior tibial artery (arrowhead). A, Axial image from a computed tomography angiogram showing small common femoral arteries (arrowheads) and bilateral persistent sciatic arteries posteriorly (open arrows). B, Volume rendering of the same patient showing the persistent sciatic arteries (open arrows) originating from the internal iliac arteries (arrowheads, common femoral arteries). The anterior and posterior tibial arteries continue into the foot in 95% of individuals, while the peroneal artery terminates above the ankle in an equal percentage. When either the anterior or posterior tibial artery is congenitally absent in the calf, the peroneal artery may continue into the foot in its stead. Rather than memorize minutiae, it is best to be familiar with the classic anatomy described and use it as a basis when interpreting imaging studies. The arcuate artery curves toward the lateral edge of the foot along the dorsal aspect of the metatarsal bone bases, supplying the dorsal metatarsal arteries to the distal foot before anastomosing with distal branches of the plantar arteries. The posterior tibial artery passes posterior and inferior to the medial malleolus, and then bifurcates into the medial and lateral plantar arteries. Occlusion of the tibioperoneal trunk and the proximal tibial arteries results in collateral supply from the sural and genicular arteries. The peroneal artery is the most common source of collateral supply, in that it is frequently spared in occlusive disease and occupies a central location in the calf. Occlusion of either the dorsalis pedis or posterior tibial artery distal to the medial malleolus is well tolerated if the plantar arches are intact. Occlusion of both the proximal dorsalis pedis and the inframalleolar posterior tibial artery is collateralized by tarsal and metatarsal arteries. Noninvasive physiologic testing provides an objective measure of disease that can be used to follow patients and document outcomes of interventions (Box 15-2). Collateralization around chronic left common femoral artery occlusion (white arrowheads) in an adolescent due to cardiac catheterization as an infant. There are well-developed collaterals from ipsilateral hypogastric branches (black arrowhead) and contra lateral external pudendal arteries (black arrow). The femoral, popliteal, dorsalis pedis, and posterior tibial arterial pulses should be checked in both legs, regardless of the laterality of symptoms.

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