Clinical Director, Eastern Virginia Medical School
Aortic dissection in Marfan syndrome is usually type A arteria braquial best telmisartan 40mg, that is blood pressure ear buy discount telmisartan, starts in the ascending aorta and can extend to a variable degree distally lowering blood pressure without medication quickly buy 40 mg telmisartan overnight delivery. About 10% of dissections in Marfan syndrome begin distal to the origin of the left subclavian artery (type B) heart attack album buy 20mg telmisartan fast delivery. Type A dissection necessitates immediate repair, given the high risk of life-threatening complications if not treated promptly. Medical management in patients with Marfan syndrome includes -Blockers, which have been shown to reduce the risk of aortic dilatation and aortic dissection. The beneficial effect of -blockers is largely due to the reduction in heart rate and the rate of pressure increase in the aorta, which leads to less stress on the aortic wall. Angiotensin receptor blockade with losartan has been shown to slow the rate of aortic root dilatation in animal models of Marfan syndrome, secondary to mitigation of excessive transforming growth factor -signaling. However, the evidence for its use in humans is less compelling although a trial of its use in children with Marfan syndrome suggested efficacy similar to -blockade in reducing aortic dilatation. Certainly, it seems appropriate to consider its use in Marfan patients with adequate blood pressure on -blockade. Calcium blockers have been associated with higher risk of dissection and should be avoided. Because of the risk of acute aortic dissection, patients with Marfan syndrome should be counseled to avoid isometric exercise, including heavy weight lifting, contact sports, and competitive athletics. Mitral valve prolapse commonly occurs in patients with Marfan syndrome and is more common in women. The incidence is as high as 60% to 80%, and progressive mitral regurgitation occurs in about 25% of patients. The valve leaflets are usually thickened and redundant, and occasionally ruptured chordae or prolapse may be present. Standard management for chronic severe mitral regurgitation is indicated in symptomatic patients, with repair of the mitral apparatus if possible, but replacement may be necessary when the leaflets are very redundant or there is severe annular calcification or chordal damage. Dilated cardiomyopathy independent of, or out of proportion to , valvular abnormalities can occur in patients with Marfan syndrome. This has been hypothesized to be secondary to a potential role of fibrillin mutations in the reduction of myocardial function. Arrhythmias, both supraventricular and ventricular, can occur in patients with Marfan syndrome. Patients are predisposed to more aggressive and widespread vascular disease, including aneurysm formation and dissection, compared with Marfan syndrome, with a mean age of death of 26 years. Arterial rupture or dissections are the major causes of mortality in these patients and can occur in the thoracic or abdominal vessels, including aortic rupture or dissection. The median age of survival was about 48 years in a study of 220 patients with this disorder. In the same study, 25% of patients had a medical or surgical complication by the age of 25 years and >80% had such complications by the age of 40 years. Pregnant women have a 50% chance of transmitting the disorder to the child and about 11. Pregnancy should be considered high risk, and women should be counseled against it. Sarcoidosis is an idiopathic systemic granulomatous inflammatory disease affecting mainly the lungs, but can involve the lymph nodes, skin, eyes, heart, kidneys, musculoskeletal system, nervous system, and endocrine system. Cardiac involvement is found in 25% of patients with sarcoidosis on autopsy, but only 5% of patients have clinically apparent cardiac involvement. Arrhythmias can vary from conduction disturbances, including heart block to fatal ventricular arrhythmias. Complete heart block is the most common abnormality in patients with clinically evident sarcoidosis and is found in 20% to 30% of patients. Granulomatous infiltration of the ventricular myocardium can set up foci of automaticity, leading to ventricular arrhythmias. Sudden cardiac death caused by an arrhythmia is one of the leading causes of death (>60%) in patients with sarcoidosis. Congestive heart failure may occur secondary to widespread infiltration of the myocardium. Progressive congestive heart failure is the second most common cause of death in patients with sarcoidosis. Pericardial involvement can manifest as pericarditis, pericardial effusion, and constrictive pericarditis. Endomyocardial biopsy with finding of noncaseating granulomas has high specificity, but poor sensitivity owing to the patchy nature of myocardial involvement particularly in the basal septum, whereas the location of biopsy is often the apical septum. Electrocardiogram often reveals conduction abnormalities but has poor sensitivity. Echocardiographic findings include increased ventricular septal thickness (secondary to granulomatous expansion) or wall thinning (because of fibrosis), aneurysms, regional wall motion abnormalities, and eventually ventricular dilatation. Corticosteroid therapy can halt cardiac disease progression and improve survival; however, it does not prevent sudden cardiac death. Pacemaker implantation is often necessary in cases of symptomatic heart block or asymptomatic high-grade conduction disease. Cardiac transplantation for cardiac sarcoidosis is rarely used, because the disease can recur in the transplanted heart. A report of the American College of Cardiology Foundation/American Heart Association Task Force on practice guidelines, American Association for Thoracic Surgery, American College of Radiology, American Stroke Association, Society of Cardiovascular Anesthesiologists, Society for Cardiovascular Angiography and Interventions, Society of Interventional Radiology, Society of Thoracic Surgeons, and Society for Vascular Medicine. Coexistence of ischemic heart disease and rheumatoid arthritis patients: a case control study.
The aorta is rightward and anteriorly displaced enrique iglesias heart attack purchase telmisartan 80 mg with amex, whereas the pulmonary artery occupies a position more leftward and posterior pulse pressure is calculated by discount telmisartan 40mg with visa. This is the most common pattern arrhythmia ecg interpretation discount 80 mg telmisartan amex, but other configurations can also be seen blood pressure chart systolic diastolic purchase cheap telmisartan, such as side-by-side great arteries with the aorta to the right or an aorta directly anterior to the pulmonary artery. Patients with these associated cardiac anomalies are considered to have complextransposition, whereas patients without these associated anomalies are considered to have simple transposition. The aortic sinuses are described according to their relationship to the pulmonary artery, such that the "facing sinuses" are closest to the pulmonary artery. The most frequent coronary arrangement is when the "left-facing" sinus gives rise to the left main coronary artery, whereas the "right-facing" sinus gives rise to the right coronary artery. Without surgical intervention, survival beyond infancy is dismal, with 89% mortality by the first year of life and worse outcomes for those without an associated lesion to allow for adequate mixing of blood. At birth, infants are treated with intravenous prostaglandin E to keep the ductus arteriosus open, and some may undergo a Rashkind procedure (Table 31. Surgical repairs include the atrial switch procedure (Senning or Mustard operation), the arterial switch procedure. Although no longer cyanotic, these patients have a host of mid- to late-term morbidities that require lifelong surveillance. Patients who have undergone an arterial switch procedure are approaching adulthood only now and presenting in adult congenital cardiology clinics. They have a systemic right ventricle, which, over time, can develop systolic dysfunction and progressive tricuspid regurgitation. These patients may present with signs and symptoms of congestive heart failure-the most common cause of death. Arrhythmias are common, and patients may present with palpitations, presyncope, or syncope. Venous baffle obstruction can lead to peripheral edema, hepatomegaly, ascites, and fatigue because of low cardiac output. Pulmonary venous baffle obstruction can lead to fatigue, exertional dyspnea, and chronic cough. Baffle leaks are often asymptomatic, but large leaks can lead to intracardiac shunting and cyanosis. Audible splitting of the S2 may indicate the development of pulmonary hypertension. This has become the standard corrective surgery for those born without significant left ventricular outflow obstruction. Few will present with chest pain, and in these patients ischemia must be ruled out. Both atrial and ventricular arrhythmias are mid- to late-term complications, and patients with these conditions may present with palpitations or syncope. Conduit obstruction may manifest as insidious exercise intolerance, dyspnea, or new-onset arrhythmias. On physical examination, the character of the pulmonic ejection murmur should be carefully noted to evaluate for conduit obstruction. In patients who have undergone an atrial switch operation, the electrocardiogram may display an ectopic atrial or junctional rhythm because of loss of sinus node function. After a Rastelli operation, the electrocardiogram is notable for a right bundle branch block, and patients may develop complete heart block. Color Doppler is helpful in detecting baffle leaks or obstruction, although more detailed analysis may require transesophageal echocardiography. For those who have undergone arterial switch, transthoracic echocardiography can assess left ventricular function and help exclude supravalvular and pulmonary artery stenosis. In patients who have undergone arterial repair, right and left ventricular function can be quantitated and both the right and left outflow tracts examined. Focus is placed on the great arteries to look for the presence of supravalvular and branch pulmonary artery stenosis as well as dilation of the neo-aorta. Cardiopulmonary testing is very useful in detecting subtle clinical changes and decrease in functional capacity. As mentioned previously, there is often a discrepancy between self-reported symptoms and performance on metabolic exercise testing. Patients who have undergone atrial switch often have chronotropic incompetence and may benefit from pacemaker implantation. Stress testing may be useful in patients after arterial switch to detect coronary artery stenosis and resultant ischemia. Quantitative pulmonary flow scans are an important part of the diagnostic workup for suspected pulmonary artery or branch pulmonary artery stenosis in those who have undergone arterial switch repair. It is useful to obtain these scans before and after potential intervention to assess for functional improvement. Cardiac catheterization does not have a role in the routine management of these adult patients. Follow-up should focus on potential late complications after repair and depends on the type of surgery the patient has undergone. Arterial switch (1) Supravalvular or peripheral pulmonary artery stenosis (2) Pulmonary outflow tract obstruction (3) Neo-aortic regurgitation and aortic root dilation (4) Coronary artery stenosis leading to ischemia and sudden death (5) Left ventricular dysfunction (6) Endocarditis c.
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Hibernating myocardium represents ischemic myocardium that has undergone chronic adaptive changes at a cellular level hypertension knowledge questionnaire discount telmisartan 20 mg overnight delivery. Findings include abnormal perfusion hypertension education materials telmisartan 20mg line, rest myocardial dysfunction (that typically improves with revascularization) prehypertension and lupus purchase telmisartan 80mg amex, and augmented contraction with stress heart attack with pacemaker buy cheapest telmisartan and telmisartan. Infarcted myocardium is nonviable scar tissue that has lost its cellular architecture and classically does not become functional even if revascularized. It is difficult to discern clinically which patients are more likely to have a higher percentage of viable (hibernating, ischemic, or stunned) myocardium and which do not, and thus, there is significant reliance on imaging to help assess this. In general, the choice of technique is guided more by the imaging capabilities of the treating medical center rather than individual patient characteristics. Positron-emitting isotopes emit two high-energy (511 keV) photons in opposite directions, each of which is detected by a camera (those that do not arrive in temporal pairs are ignored). Concomitant low-dose computed tomography imaging allows software correction of attenuation of photon counts in areas where there is more tissue between the heart and the detector and this attenuation correction is particularly useful in obese patients or in those with prominent breasts. Rubidium-82 (Rb82) is a potassium analogue with a short halflife (1 minute), rapidly taken up by intact myocardial cells via the sarcolemmal Na/K pump and is a marker for normal perfusion. When used in conjunction with pharmacologic stress testing (usually with a vasodilator such as regadenoson), it can also indicate ischemia, with reduced stress tracer counts indicating ischemia. Recently, generators have become commercially available which contain strontium-82 that decays by electron capture to produce positronemitting rubidium-82. Oxygen 15 water can also be used as a perfusion tracer, but needs a cyclotron and is uncommonly used in conventional practice. Other agents such as carbon 11 acetate and carbon 11 palmitate are uncommonly used. In normal myocardial cells, free fatty acids are used preferentially, but during periods of ischemia, stunning, and hibernation, metabolism changes so that glucose is primarily used. Normal tissue shows normal rest and stress perfusion with high metabolic tracer uptake. Stunned tissue shows normal rest and stress perfusion with high metabolic tracer uptake and reduced regional wall motion. Ischemic tissue shows normal perfusion at rest, decreased perfusion at stress, and high metabolic tracer uptake. Hibernating tissue shows decreased perfusion at stress and rest with high metabolic tracer uptake. Scar shows decreased perfusion at rest and stress with no metabolic tracer uptake. Agents with short half-lives need to be generated on-site and therefore are limited to facilities that perform a high-enough volume of studies to justify the cost. This technique offers high spatial resolution to aid quantification of the extent of myocardial scar (nonviable tissue) and this explains its low false-negative rate and high negative predictive ability. Images are obtained 10 to 20 minutes after gadolinium injection, at which time the contrast has already washed in and out of healthy tissue, but has not yet had time to wash out of the scarred tissue which is therefore demonstrated by hyperenhancement on imaging. First, viability assessment requires the use of gadolinium which generally cannot be used in patients with a glomerular filtration rate of less than 30 mL/min because of the risk of nephrogenic systemic fibrosis. More recently, repeated gadolinium exposure has also been linked to cerebral deposition whose significance is unclear. Many patients cannot adequately participate and others have unacceptable claustrophobia which can limit the exam. For the purpose of viability assessment, the radiotracer thallium 201 is preferred specifically because of its redistribution kinetics. As a potassium analog, it is rapidly taken up by cell membrane Na/K pumps concentrating primarily in the intracellular space with peak myocardial concentration at 10 minutes. Thereafter, the tracer undergoes continual exchange between the extracellular and intracellular spaces and redistributes to poorly perfused viable cells but not scar tissue. Rest/redistribution: the tracer is injected and the heart imaged at rest approximately 10 to 45 minutes after initial injection, followed by reimaging 4 hours later. Perfusion defects on the initial image that improve on reimaging represent areas of ischemic/hibernating myocardium. Perfusion defects on initial imaging that improve on reimaging represent areas of ischemic/hibernating myocardium. Defects that do not improve represent scar (although without reinjection, this protocol has a relatively lower sensitivity). A second reinjection after acquisition of the 4-hour redistribution images, with third time imaging carried out 18 to 24 hours later, increases the identification of viable myocardium that may appear as scar on the 4-hour post-stress images. Limitations of this technique include exposure to ionizing radiation, relatively low spatial resolution, and attenuation artifacts. Assessment of contractile reserve in response to escalating dobutamine infusion forms the basis for assessing viability by echocardiography. Stunned or hibernating myocardial segments augment with stress but typically in a somewhat blunted fashion (uniphasic response). Ischemic myocardial segments classically exhibit an inducible biphasic response, whereby there is an initial improvement at low-dose dobutamine because of the inotropic effect, but regression at higher dose because of increased myocardial oxygen demand in the presence of a significant perfusion abnormality. Scarred myocardial segments classically exhibit akinesis at rest and with dobutamine. Limited image quality particularly in obese patients may be suboptimal despite the use of echo contrast.
Preganglionic fibers from lower thoracic and upper lumbar segments generally synapse in prevertebral ganglia (D) blood pressure medication used for sleep telmisartan 80mg low price, from which postganglionic fibers travel to blood vessels hypertension journal impact factor telmisartan 20mg without prescription. Postganglionic sympathetic fibers (long compared to postganglionic parasympathetic fibers) travel to target organs where they innervate arteries and veins; capillaries are not innervated blood pressure zolpidem discount telmisartan online american express. Small branches of these efferent nerves are found in the adventitia (outer) layer of blood vessels heart attack types buy telmisartan pills in toronto. Varicosities, which are small enlargements along the sympathetic nerve fibers, provide the site of neurotransmitter release. Sympathetic activation increases chronotropy, dromotropy, and inotropy (see Table 6-1). In blood vessels, sympathetic activation directly constricts both resistance and capacitance vessels, thereby increasing systemic vascular resistance (and arterial blood pressure) and decreasing venous capacitance (which increases venous pressure) (see Table 6-1). As described in Chapter 7, sympathetic activation of the heart leads to paradoxical coronary vasodilation because increased cardiac activity produces metabolic coronary vasodilation that overrides the direct sympathetic vasoconstrictor effects on the coronary vessels. Sympathetic activation of resistance vessels significantly contributes to the vascular tone in many organs. When this is done, blood flow increases, the amount of which depends upon the degree of sympathetic tone and the strength of local autoregulatory mechanisms that will attempt to maintain constant blood flow (see Chapter 7). For example, if -adrenoceptors in the forearm circulation are blocked pharmacologically, blood flow increases two- or threefold. Over time, however, intrinsic autoregulatory mechanisms restore normal tone and blood flow. As described further in Chapter 7, the vascular response to sympathetic activation differs among organs. Nevertheless, generalized sympathetic activation of the circulation increases arterial pressure and reduces organ perfusion throughout the body except in the heart and brain. This is important because without removal of vagal influences on the heart, the ability of enhanced sympathetic activity to increase heart rate is impaired. The reason for this is that vagal influences are dominant over sympathetic influences in the heart. Regions within the hypothalamus can integrate and coordinate cardiovascular responses by providing input to medullary centers. Studies have shown that electrical stimulation of dorsomedial hypothalamus produces autonomic responses that mimic those that occur during exercise, or the flight-or-fight response. These coordinated responses include sympathetic-mediated tachycardia, increased inotropy, catecholamine release, and systemic vasoconstriction. For example, sudden fear or emotion can sometimes cause vagal activation leading to bradycardia, withdrawal of sympathetic vascular tone, and fainting (vasovagal syncope). Fear and anxiety can lead to sympathetic activation that causes tachycardia, increased inotropy, and hypertension. Chronic sympathetic activation induced by long-term emotional stress can result in sustained hypertension, cardiac hypertrophy, and arrhythmias. Activation of sympathetic efferent nerves to the heart releases the neurotransmitter norepinephrine that binds primarily to 1-adrenoceptors located in nodal tissue, conducting tissues, and myocardium. There are also postjunctional 2-adrenoceptors in the heart; however, they are normally less important than 1-adrenoceptors. Released norepinephrine can also bind to prejunctional 2-adrenoceptors located on the sympathetic nerve terminal. These receptors inhibit norepinephrine release through a negative feedback mechanism. In the heart, this neurotransmitter binds to muscarinic receptors (M2) principally in nodal tissue, and in atrial myocardium. In blood vessels, norepinephrine released by sympathetic adrenergic nerves preferentially binds to postjunctional 1-adrenoceptors to cause smooth muscle contraction and vasoconstriction. Similar responses occur when norepinephrine binds to postjunctional 2-adrenoreceptors located primarily on small arteries and arterioles, although postjunctional 1-adrenoceptors are generally the more important -adrenoceptor subtype in most vessels. In addition, norepinephrine can bind to prejunctional 2-adrenoreceptors, which acts as a negative feedback mechanism for modulating norepinephrine release. Blood vessels possess postjunctional 2-adrenoceptors in addition to -adrenoceptors. Activation of postjunctional 2-adrenoceptors by norepinephrine (and, more importantly, by circulating epinephrine) causes vasodilation in the absence of opposing -adrenoceptor-mediated Sympathetic Parasympathetic vasoconstriction. To observe this 2-adrenoceptorinduced vasodilation experimentally, one can stimulate vascular sympathetic nerves in the presence of complete -adrenoceptor blockade. Normally, this small 2-receptor-mediated vasodilator effect of norepinephrine is completely overwhelmed by simultaneous -adrenoceptor activation, leading to vasoconstriction. Baroreceptor Feedback Regulation of Arterial Pressure As described above, sympathetic nerves play an important role in regulating systemic vascular resistance and cardiac function, and therefore arterial blood pressure. But, how does the body control the systemic vascular resistance and cardiac output to establish and maintain an arterial blood pressure to ensure adequate organ perfusion Arterial blood pressure is regulated through negative feedback systems incorporating pressure sensors. Arterial baroreceptors are found in the carotid sinus (at the bifurcation of external and internal carotids) and in the aortic arch. The arterial baroreceptors respond to the stretching of the vessel walls produced by increases in arterial blood pressure. Carotid sinus receptors are located on the internal carotid artery just above the junction with the external carotid artery. Afferent nerves from the aortic arch receptors join the vagus nerve (cranial nerve X), which then travel to the medulla. Each individual receptor has its own threshold and sensitivity to changes in pressure; therefore, additional receptors are recruited as pressure increases. Overall, the receptors of the carotid sinus respond to pressures ranging from about 60 to 180 mm Hg.
