Myocardial and Pericardial Disease

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[edit] Myocardial and Pericardial Disease

Edward K. Kasper

Kenneth L. Baughman

[edit] EPIDEMIOLOGY AND ETIOLOGY

Cardiomyopathies are diseases of the heart muscle. The three categories of cardiomyopathy are dilated, hypertrophic, and restrictive.^[1] Ventricular enlargement and contractile dysfunction characterize dilated cardiomyopathy, the most common type. Hypertrophic cardiomyopathy is characterized by ventricular hypertrophy, often asymmetric and involving the left ventricular septum. Systolic left ventricular outflow tract gradients are common. Only 4% of patients with cardiomyopathy have the hypertrophic form. Restrictive cardiomyopathy is characterized by restricted ventricular filling with normal ventricular systolic function and wall thickness. Restrictive cardiomyopathy is the least common form in the developed world, but may account for 15% to 25% of the deaths due to heart disease in equatorial Africa.^[2] These functional categories are not absolute and overlap may exist. Reliable incidence and prevalence data on restrictive cardiomyopathy do not exist. The prevalence of dilated cardiomyopathy in 1984 was 36.5/100,000 person-years, and that of hypertrophic cardiomyopathy was 19.7/100,000 person-years.^[3] As with heart failure, the prevalence of dilated cardiomyopathy increases with age and is more common in males.

The most common cause of dilated cardiomyopathy is coronary artery disease with prior myocardial infarction. A partial listing of the possible causes of dilated cardiomyopathy in the absence of coronary artery disease is found in Box 68-1. In evaluating patients with dilated cardiomyopathy, one must exclude “look-alikes” not due to primary muscle disease, including focal coronary artery disease (left ventricular aneurysm), primary valvular disease (aortic stenosis and aortic or mitral regurgitation), and pericardial disease (pericardial tamponade or constrictive pericarditis). The etiologies of dilated cardiomyopathy that may be reversible include myocarditis, metabolic disorders (thyroid disease or pheochromocytoma), toxicity (alcohol or drugs), tachycardia-induced, infiltrative diseases (hemochromatosis or sarcoidosis), septic shock, carnitine deficiency, and peripartum.

Hypertrophic cardiomyopathy is recognized as an autosomal dominant disease in approximately 50% of the patients. Multiple genes on several chromosomes are associated with familial hypertrophic cardiomyopathy. All these genes code for proteins of the contractile apparatus, of which cardiac myosin heavy chain seems to be the most frequently mutated.^[4] Some patients with hypertrophic cardiomyopathy have no family history due to variable penetrance or spontaneous mutations. Patients with hypertension may develop a hypertensive hypertrophic cardiomyopathy. These patients, presumably in response to longstanding hypertension, develop significant concentric hypertrophy. Other causes of hypertrophic cardiomyopathy are listed in Box 68-1.

Restrictive cardiomyopathy is commonly due to the infiltration of a foreign substance in or around the myocardial cells. Etiologies include amyloidosis, hemochromatosis, and sarcoidosis. Virtually all patients with these disorders display evidence of systemic illness, making the diagnosis more obvious. Noninfiltrative forms also exist and are listed in Box 68-1.

Pericardial disease may cause congestive heart failure due to restriction of ventricular diastolic filling. Potential forms of involvement include pericarditis, pericardial effusion possibly resulting in tamponade, and pericardial constriction. Acute pericarditis, or inflammation of the pericardium, is the most common form of pericardial involvement. It is most often idiopathic or caused by viral infection or acute myocardial infarction. Other causes are listed in Box 68-2. It is more common in men than women and adults than children. Pericardial effusion develops as a response to pericardial injury, often inflammatory pericarditis. Pericardial constriction occurs when a fibrotic, thickened, and adherent pericardium restricts diastolic filling of the heart.^[5] It usually begins with an episode of acute pericarditis resulting in pericardial effusion followed by pericardial fibrosis and thickening. Most cases of acute pericarditis do not result in constriction. Constrictive pericarditis may be difficult to differentiate from restrictive cardiomyopathy.

[edit] PATHOPHYSIOLOGY

Dilated cardiomyopathy is initiated by an insult that decreases left ventricular contractility. This insult may be coronary disease, a viral illness, alcohol, or the toxic effect of a medication. The decrease in contractility reduces stroke volume and results in activation of the renin-angiotensin system, adrenergic system, and other neurohormones as mentioned in Chapter 65 . Neurohormonal activation leads directly and indirectly to the syndrome of congestive heart failure and the progressive worsening of ventricular function. Dilated cardiomyopathy is associated with a poor prognosis, with only 50% survival 5 years after diagnosis.^[6]

In hypertrophic cardiomyopathy, the ventricle is characterized by abnormalities of diastolic relaxation and increased contractility with hyperdynamic ejection of ventricular volume.^[7] Because of dramatic hypertrophy, the left ventricular cavity is small and diastolic filling is incomplete, resulting in elevated ventricular diastolic pressure. Although this is the antithesis of dilated cardiomyopathy, the end result is the same, with elevated filling pressures and a low stroke volume. Dynamic left ventricular outflow tract gradients are commonly seen and probably result from the anterior leaflet of the mitral valve contacting the ventricular septum in the outflow tract. The gradient may be labile, increasing with increased contractility as well as decreased preload or afterload. A gradient from the left ventricular apex to just below the aortic valve of 50 to 150 mm Hg is not uncommon. Abnormalities of diastolic filling are always present whether or not a pressure gradient is present. Late in the course of the disease, a picture of dilated cardiomyopathy may develop most likely due to repeated episodes of ischemia with resulting fibrosis. The natural history of hypertrophic cardiomyopathy is variable, with some patients remaining stable for years. The risk of sudden death is highest in children and young adults and occurs especially during or right after vigorous physical exertion.

Restrictive cardiomyopathy is characterized by an infiltration in and around the myocardial cells of a substance that alters myocardial relaxation. Diastolic compliance is much more dramatically influenced than systolic contractility until late in the course of the disease. Like patients with hypertrophic cardiomyopathy, these patients have markedly elevated filling pressures and a low stroke volume. Unlike patients with hypertrophic cardiomyopathy, patients with restrictive cardiomyopathy may have normal ventricular wall thickness. Filling pressures are usually equal in both ventricles, and diastolic pressure tracings demonstrate a “dip and plateau” configuration also seen in constrictive pericarditis. The prognosis in restrictive cardiomyopathy is variable. Restrictive cardiomyopathy due to amyloidosis is associated with an especially poor prognosis. Treatment of the primary disorder associated with restrictive cardiomyopathy only rarely improves the patient's overall prognosis.

Injury, infection, or inflammation of the pericardium may result in fluid accumulation. If the fluid accumulates rapidly, even small amounts may dramatically decrease ventricular filling due to the inability of the pericardium to stretch abruptly and the subsequent compression of the heart. Pericardial effusions accumulated over long periods, however, may result in massive accumulations of fluid before symptoms occur. As the pericardium surrounds the right and left ventricle, pressure in the pericardial space is equally distributed to both ventricles. Pericardial pressure elevation will increase both left and right ventricular end-diastolic pressures. Therefore, when the pressure in the pericardial space is higher than the intrinsic ventricular diastolic pressure, the diastolic ventricular pressures will rise to the pericardial pressure. Additionally, pericardial fluid or constriction may limit ventricular filling. When the mitral and tricuspid valves are open, diastolic pressures in all chambers of the heart are equivalent and are also equal to the pericardial pressure. As with the cardiomyopathies, the end result of pericardial disease may be an increase in diastolic filling pressures and a decrease in stroke volume. The natural history of pericardial constriction is progressive hemodynamic compromise. However, all forms of pericardial disease are treatable and, in fact, virtually curable. The primary mission of the treating physician is to differentiate pericardial disease, which is curable, from restrictive cardiomyopathy, which is terminal. Pericardial effusions can be drained, regardless of their etiology, and the patient's hemodynamics normalized. Pericardial constriction can be prevented by appropriately treating the cause of the pericardial effusion. Pericardial constriction demands surgical pericardiectomy, which is usually curative.

Since all forms of cardiomyopathy, pericardial effusion, and constrictive pericarditis may result in the heart failure syndrome, it is important to identify the underlying pathophysiology so that appropriate treatment can be initiated.

[edit] PATIENT EVALUATION

[edit] History

Patients with cardiomyopathy, pericardial effusion, or constrictive pericarditis may present with the signs and symptoms of heart failure as outlined in Chapter 65 . In addition, patients with dilated cardiomyopathy may have embolic events originating from the heart. Ventricular dysrhythmias are common in all forms of cardiomyopathy and may result in palpitations, lightheadedness, dizziness, presyncope, syncope, and sudden death. Supraventricular dysrhythmias, particularly atrial fibrillation, are also common and may result in symptomatic deterioration.

Some specific historical features may help distinguish the form of cardiomyopathy present. Patients with hypertrophic cardiomyopathy more frequently complain of ischemic chest pain and often have dizziness following exercise or with Valsalva's maneuver. Patients with restrictive cardiomyopathy, pericardial effusion, or constrictive pericarditis often display right-sided signs and symptoms of congestion much in excess of left-sided. Dramatic elevation of the right atrial pressure, commonly seen in restrictive cardiomyopathy and constrictive pericarditis, results in massive jugular venous distention, hepatomegaly, ascites, anorexia, abdominal pain, and peripheral edema.

A commonly encountered error in the management of patients with cardiomyopathy is the misdiagnosis of a patient presenting with cough, congestion, and breathlessness. Such patients are usually thought to have bronchitis and are treated with antibiotics before the myocardial or pericardial etiology is recognized. Orthopnea and paroxysmal nocturnal dyspnea are clues to a cardiac cause of the presenting symptoms and indicate the need for echocardiography. Patients may also present with asymptomatic cardiomyopathy or pericardial disease. All family members of a patient with hypertrophic cardiomyopathy should be screened for the disorder.

Patients with pericardial effusion or constriction often begin with acute pericarditis. These patients present with precordial discomfort, which is usually more omnipresent than angina and is position-dependent, being exacerbated by lying down and eased by sitting up and leaning forward. The pain is usually retrosternal and sharp, and may radiate to the neck or shoulder. Unlike angina, the pain lasts for hours or days and is not exacerbated by exertion. Pericarditis may be associated with pleural inflammation as well, resulting in a pleuropericardial syndrome with exacerbation of the pain with deep inspiration or cough. These symptoms may be confused with the symptoms of acute myocardial infarction, pulmonary emboli, or aortic dissection. Acute pericarditis may also present with dyspnea, at least partly caused by the need to breathe shallowly in order to avoid chest pain.

[edit] Physical Examination

[edit] Jugular Venous Pressure.

Patients with congestive heart failure have elevations of the right atrial pressure and therefore distended jugular veins. Patients with dilated cardiomyopathy have modest distention of the jugular veins and often large v waves due to tricuspid regurgitation. In these cases the regurgitation is due to dilation of the tricuspid annulus secondary to myocardial disease. Patients with hypertrophic cardiomyopathy display prominent A waves in the venous pulse. This is due to the increased right atrial pressure necessary to force blood into the stiff right ventricle. Patients with restrictive cardiomyopathy display even greater elevations of the A waves for similar reasons. Patients with pericardial tamponade or constriction display dramatic abnormalities of the venous pressure. These patients have equally prominent A and v waves. Patients with pericardial constriction have dominant x and y descents after the A and v waves, whereas patients with pericardial tamponade display only a prominent x descent.

[edit] Carotid Pulse.

In dilated and restrictive cardiomyopathy, as well as pericardial disease, the carotid volumes are diminished due to the low stroke volume of the left ventricle. In dilated cardiomyopathy, the rate of rise of the carotid pulse is diminished. The carotid upstroke in patients with restrictive cardiomyopathy is usually maintained until late in the course of the disease. In pericardial disease the carotid upstroke is normal, although decreased in volume. Patients with hypertrophic cardiomyopathy have a hyperdynamic carotid upstroke due to the ejection of blood from the ventricle. A bifid contour of the peak of the carotid upstroke is associated with hypertrophic cardiomyopathy and left ventricular outflow tract obstruction. It is due to the early rapid ejection of blood from the ventricle followed by outflow tract obstruction and then a later secondary peak of ejection. The peripheral pulses are relatively indistinguishable in these disorders, with the exception of the paradoxical pulse seen in pericardial tamponade and constrictive pericarditis. Pulsus paradoxus is an inspiratory decrease in the amplitude of the arterial pulse greater than 10 mm Hg. Other disorders, such as chronic obstructive pulmonary disease (COPD), restrictive cardiomyopathy, and massive pulmonary embolism, may also cause pulsus paradoxus.

[edit] Lung.

When the left atrial pressure is elevated, it is transmitted to the pulmonary veins. This results in exudation of fluid into the alveoli, producing crackles. Patients may also have peribronchial edema, resulting in wheezing. Not infrequently, patients with severe disease have absolutely clear lung fields, particularly if the left atrial hypertension has occurred over a long period. Patients with restrictive cardiomyopathy may display lung involvement with a primary process such as sarcoidosis or amyloidosis.

[edit] Heart.

The point of maximal impulse in patients with dilated cardiomyopathy is markedly displaced and weak, often with a palpable S₃ gallop. Patients with hypertrophic cardiomyopathy have a dynamic, forceful, heaving left-ventricular point of maximal impulse. Those with restrictive cardiomyopathy have a weakened but usually minimally displaced point of maximal impulse. Patients with pericardial disease have a quiet precordium. Heart sounds are also variable. Patients with dilated cardiomyopathy usually have soft heart sounds and S₃ gallops. Hypertrophic cardiomyopathies usually have brisk heart sounds and S₄ gallops, depending on the degree of compliance abnormality in the left ventricle and the rate of deceleration of blood entering the cavity. Restrictive cardiomyopathy patients often have S₄ gallops. Patients with pericardial constriction may have an early diastolic pericardial knock, which must be differentiated from an S₃ gallop. The pericardial knock usually occurs earlier and has a higher frequency than the typical S₃.

Patients with dilated cardiomyopathy develop murmurs of mitral and tricuspid regurgitation as a result of annular dilation and malalignment of the chordae tendineae. Patients with hypertrophic cardiomyopathy often have an outflow murmur, which is typically harsh, diamond-shaped, and heard best in the aortic region. It is similar to aortic stenosis and often associated with a blowing murmur at the apex of the heart compatible with mitral regurgitation. Patients with restrictive cardiomyopathy frequently have no murmurs whatsoever. Patients with acute pericarditis usually have a one-, two-, or three-component friction rub. The components of the rub are usually described as presystolic, ventricular systolic, and rapid ventricular filling. There are therefore two diastolic components and one systolic component to the typical three-component friction rub. The ventricular systolic component is the loudest and is present in almost all cases. The rub is a scratchy, grating, high-frequency sound that may be evanescent. Finally, a friction rub may be heard in patients with small or large pericardial effusions.

[edit] Abdomen.

The liver may be enlarged in any patient with right atrial hypertension. Since pericardial effusion and constrictive pericarditis, as well as restrictive cardiomyopathy, more often have higher right-sided pressures than dilated or hypertrophic cardiomyopathy, the liver is frequently more congested in these diseases. Similarly, the liver may be involved in certain of the primary etiologies of restrictive cardiomyopathy. Ascites is much more common in patients with restrictive or constrictive heart disease.

[edit] Extremities.

Patients with pericardial, restrictive, and hypertrophic disease have less edema than patients with dilated cardiomyopathy, probably due to the lower cardiac output found in patients with dilated cardiomyopathy.

[edit] Subtle or Misleading Findings.

Often the jugular venous pressure elevation is not appreciated. This is due to the dramatic distention in the veins when the patient is supine. The patient's head and upper body must be raised until a meniscus is evident in the vein to judge the height of the venous pressure. Even if the elevated venous pressure is appreciated, A and v waves are often not appreciated, nor are the x and y descents. Carotid pulsations may be mistaken for venous pulsations. The carotid pulse is medial to the venous pulse and protected by the two heads of the sternocleidomastoid muscle.

The point of maximal impulse is frequently missed due to the patient's habitus and should be felt for in the left lateral decubitus position if not apparent with the patient supine.

The differentiation of a pericardial knock from an S₃ gallop is difficult in timing but straightforward by the nature of the sound produced. The S₃ is a low-frequency sound, whereas the pericardial knock has a high frequency that is more like a typical first or second heart sound. Patients with midsystolic clicks are often misdiagnosed as having a pericardial knock or an S₃ gallop. Strict attention to the timing of the sound should differentiate systolic clicks from diastolic gallops. Rubs and murmurs may be misinterpreted.

[edit] DIAGNOSIS

[edit] Diagnostic Procedures

The transthoracic echocardiogram is the single most useful procedure to diagnose myocardial and pericardial disease. Patients with dilated cardiomyopathy characteristically have thin left ventricular walls, a dilated left ventricular internal diastolic dimension (greater than 2.7 cm/m² body area), and poor contractility (Table 68-1). Patients with hypertrophic cardiomyopathy have markedly thickened and often asymmetric left ventricular walls, small left ventricular cavities, and hyperdynamic contractility. Patients with restrictive cardiomyopathy have normal or slightly thickened walls, a normal ventricular cavity, and normal contractility until late in the disease when systolic dysfunction may occur. Patients with amyloidosis, hemochromatosis, or interstitial fibrosis may have a speckled pattern to the left ventricular myocardium, which is suggestive of an infiltrative process. Patients with pericardial effusions are easily diagnosed with echocardiography, which also determines diastolic compliance and assesses the presence or absence of valvular disease.

Table 68-1 Echocardiographic Differentiation of Myocardial and Pericardial Disease

[edit] Etiology.

A number of studies can be performed to determine the etiology of the identified abnormality. These include blood and urine studies as well as an array of noninvasive and invasive procedures.

[edit] Diagnostic Laboratory Studies

[edit] Dilated Cardiomyopathy.

Routine screening for apathetic thyroid disease in elderly patients is recommended.^[8] Otherwise, special studies, such as antinuclear antibody testing and iron studies, are reserved for those patients with findings on history or physical examination that are suggestive of a systemic disorder.

[edit] Hypertrophic Cardiomyopathy.

Routine genetic screening to identify mutations is not yet available but probably will be shortly. Electrocardiography (ECG) and echocardiography remain the best screening tools for family members of those patients with hypertrophic cardiomyopathy.

[edit] Restrictive Cardiomyopathy.

Specific studies may be performed to identify the potential etiology of restrictive cardiomyopathy. Iron, ferritin, iron-binding capacity, and percent saturation studies are helpful in evaluating hemochromatosis. Patients with suspected amyloidosis, particularly those associated with multiple myeloma, should have serum and urinary protein electrophoresis performed. Some patients with hypereosinophilia may develop a restrictive-like cardiomyopathy due to endocardial fibrosis (Löffler's syndrome).

[edit] Pericardial Disease.

Patients with constrictive pericarditis have no distinguishing blood laboratory studies. Patients with pericarditis or pericardial effusion may have laboratory values, such as an elevated sedimentation rate, that reflect the inflammatory nature of this process. Only with a suppurative infective pericarditis would blood cultures identify the etiology.

[edit] Electrocardiography.

Patients with dilated cardiomyopathy may have atrial enlargement, low voltage, left bundle branch block, ventricular hypertrophy, and poor R wave progression, often in a pseudoinfarct pattern. Patients with a hypertrophic cardiomyopathy, on the other hand, have a dramatic increase in voltage and may display left ventricular hypertrophy with strain in addition to atrial enlargement. Restrictive cardiomyopathy patients display a dramatic decrease in voltage and are notorious for a pseudoinfarct pattern in the inferior or anterior leads. Patients with pericardial effusions similarly have low voltage but may also have electrical alternans due to swinging of the heart within the fluid-filled pericardium. Acute pericarditis is characterized by PR-segment depression and ST-segment elevation. The differentiation between pericardial inflammation and ischemia is often difficult in patients with ST-segment elevation. Patients with pericarditis always have a return of their ST-segments to baseline before inversion of their T waves, whereas patients with ischemia have persistent ST elevation while their T waves are inverted.

[edit] Chest Roentgenography.

Patients with dilated cardiomyopathy have enlargement of their cardiac silhouette, usually with evidence of four-chamber involvement. Patients with hypertrophic cardiomyopathy have less enlargement of their ventricular silhouettes and tend to have less right ventricular prominence. Restrictive cardiomyopathy patients often have normal-appearing cardiac silhouettes despite an increase in pulmonary vascularity. Patients with constrictive pericarditis may have pericardial calcification. Significant pericardial effusion results in enlargement of the cardiac silhouette.

[edit] Chest Computed Tomography Scan or Magnetic Resonance Imaging.

Constrictive pericarditis is diagnosed by the demonstration of pericardial thickening. Chest computed tomography (CT) and magnetic resonance imaging (MRI) are valuable tools in the evaluation of patients with putative constrictive pericarditis. MRI is probably the most sensitive imaging technique currently available for evaluating the thickness of the pericardium. In contrast, echocardiography is relatively insensitive.

[edit] Cardiac Catheterization.

Coronary arteriography should be performed in patients over 35 years of age with dilated cardiomyopathy and standard risk factors for coronary disease. Often, however, the left ventricular dysfunction is in excess of that which could be attributed to the degree of coronary artery disease. For clinical purposes, the degree of aortic and mitral valve disease can usually be adequately judged by echocardiography using Doppler techniques.

Catheterization may be of benefit in patients with hypertrophic cardiomyopathy to rule out associated coronary artery disease and to assess the degree of outflow obstruction. The ventricular diastolic pressures in restrictive cardiomyopathy or constrictive pericarditis display a characteristic pattern of filling. Left and right ventricular end-diastolic pressures are elevated, and the early diastolic pressure has a square root configuration due to the rapid influx of blood and achievement of maximal cavity volumes early in diastole. Additionally, patients with significant constrictive and restrictive heart disease have equalization of the diastolic pressures. Patients with restrictive disease are more likely to have a higher left ventricular than right ventricular end-diastolic pressure and typically have higher systolic pulmonary artery pressures.

[edit] Endomyocardial Biopsy.

Endomyocardial biopsy may be helpful in patients with dilated or restrictive cardiomyopathy. Table 68-2 lists the final diagnoses reached after performance of history, physical examination, routine blood work, endomyocardial biopsy, and coronary angiography, when necessary, in 673 patients referred to the Johns Hopkins Hospital for the evaluation of dilated cardiomyopathy.^[9] Many of these diagnoses are made by histologic examination, including myocarditis, amyloidosis, sarcoidosis, hemochromatosis, Adriamycin toxicity, histiocytosis X, scleroderma, and thrombotic thrombocytopenic purpura (TTP). Utilizing this approach, only 50% of the patients were considered idiopathic. Patients with new-onset dilated cardiomyopathy of less than 6-months' duration and those who are young or potential transplant candidates should undergo heart biopsy. Biopsy is of even greater benefit for patients with restrictive cardiomyopathy. The etiology can virtually always be established by endomyocardial biopsy in view of the common infiltrative causes of restrictive cardiomyopathy. The biopsy is particularly beneficial in patients with constrictive-restrictive hemodynamics, since it is less risky to perform an endomyocardial biopsy to rule out infiltrative disease than to submit the patient to an exploratory pericardiectomy to rule out constrictive pericarditis. Biopsy of patients with hypertrophic cardiomyopathy is rarely warranted.

Table 68-2 Etiology of Dilated Cardiomyopathy

[edit] Differential Diagnosis

See Box 68-3.

[edit] Dilated Cardiomyopathy

[edit] Focal Coronary Artery Disease

[edit] Left Ventricular Aneurysm.

Patients with a proximal left anterior descending obstruction may develop massive degrees of dilation and dyskinesia of the anterior wall. This can produce a markedly enlarged cardiac silhouette and a falsely low ejection fraction by gated blood pool scanning. Echocardiography or ventriculography demonstrates active inferior and lateral walls, as well as the focal nature of the left ventricular aneurysm.

[edit] Left Ventricular Pseudoaneurysm.

Patients may rarely suffer a rupture of the anterior wall that is confined to the pericardial space, which is adherent to the anterior wall due to focal pericardial inflammation. Such patients similarly show an enlargement of the left ventricular silhouette on noninvasive studies.

[edit] Primary Valvular Disease

[edit] Aortic Stenosis.

Patients with end-stage aortic stenosis may develop significant ventricular dilation and contractile dysfunction. Due to the low cardiac output generated by the failing heart, the murmur of aortic stenosis may be markedly diminished in intensity or absent.

[edit] Aortic Regurgitation.

Regurgitant lesions of the aortic and mitral valve result in a volume challenge to the left ventricle. This volume challenge is handled extraordinarily well until late in the course of decompensation. Because of the low aortic diastolic pressure and high left ventricular end-diastolic pressure, the diastolic pressure gradient is low and results in a barely audible murmur.

[edit] Mitral Regurgitation.

Of all the valvular lesions, mitral regurgitation is the most difficult to distinguish, since patients with dilated cardiomyopathy develop this murmur due to annular dilation and papillary muscle malalignment. A prior history of mitral regurgitation and the finding of moderate to severe regurgitation by noninvasive or invasive studies, as well as a finding of primary valvular pathology by echocardiography, suggest that the mitral regurgitation caused the dilated cardiomyopathy.

[edit] Mitral Stenosis.

Rarely, patients with severe mitral stenosis, pulmonary hypertension, and right heart failure develop massive enlargement of the right ventricle. This may result in a huge heart by chest x-ray and palpable as well as audible gallops.

[edit] Pericardial Disease.

Pericardial effusions may produce marked cardiac silhouette enlargement and heart failure, while ventricular function remains entirely normal. This is the most important of the lesions in differential diagnosis in view of the treatability of the disorder.

[edit] Hypertrophic Cardiomyopathy

[edit] Hypertensive Hypertrophic Cardiomyopathy.

Patients with longstanding hypertension may develop left ventricular hypertrophy and congestive heart failure.

[edit] Valvular Aortic Stenosis.

Aortic stenosis results in a significant obstruction to flow through the aortic valve as the stenosis progresses. Patients develop progressive myocardial hypertrophy in response to this increased workload, resulting in myocardial thickness.

[edit] Subaortic Stenosis.

Rarely, patients may present with discrete subaortic rings simulating hypertrophic subaortic stenosis and aortic stenosis.

[edit] Infiltrative Disorders.

Patients with amyloidosis and other infiltrative disorders may appear to have significant ventricular hypertrophy with normal or enhanced contractility early in the natural history of the disease.

[edit] Restrictive Cardiomyopathy

[edit] Hypertrophic Cardiomyopathy.

See above.

[edit] Hypertensive Hypertrophic Cardiomyopathy.

See above.

[edit] Normal Heart Size and Function.

Some patients with restrictive cardiomyopathy appear to have normal ventricular wall thickness and contractility early in their course, only to have wall thickness increase and contractility diminish over time.

[edit] Pericardial Disease

A pericardial effusion can be mistaken for any of the generalized causes of cardiomegaly noted above. Pericardial constriction may be mistaken for restrictive cardiomyopathy.

[edit] MANAGEMENT

The primary tenet is to treat the primary cause when it is identified and if treatment is appropriate. For example, patients with hypothyroidism should be treated with thyroid replacement. Patients with regurgitant or stenotic valvular lesions may be candidates for surgical correction. Similarly, patients with coronary artery disease may be appropriate for revascularization. Patients with pericardial effusions may benefit from pericardiocentesis while patients with constrictive pericarditis benefit from pericardiectomy. All of the cardiomyopathies as well as pericardial tamponade and constrictive pericarditis may present with signs and symptoms of the heart failure syndrome. It is necessary to define the cause of the heart failure syndrome to provide appropriate therapy.

[edit] Nonpharmacologic Therapy

[edit] Dilated Cardiomyopathy.

Patients with dilated cardiomyopathy may benefit from dynamic cardiomyoplasty, left ventricular reduction surgery, or heart transplantation. Dynamic cardiomyoplasty is experimental and utilizes the latissimus dorsi wrapped around the heart muscle in a complicated surgical procedure. The latissimus is stimulated with a pacemaker to contract in conjunction with the left ventricle. This is thought to prevent further ventricular dilation and perhaps augment contractility. Left ventricular reduction surgery has been applied to patients with dilated cardiomyopathy. In this experimental operation, a significant amount of the left ventricular lateral wall is surgically removed. Results from this operation and cardiomyoplasty are mixed. Cardiac transplantation, on the other hand, is a well-established treatment for all forms of end-stage heart disease. It is, however, not available to all patients due to a lack of suitable donor organs. Significant limitations due to age, pulmonary vascular resistance, diabetes, excessive obesity, extracardiac vascular disease, other comorbidities, or psychosocial factors govern the utilization of this operation. Cardiac transplantation results in the replacement of an end-stage, life-threatening heart condition with a multitude of posttransplant medical problems associated with immunosuppressive drugs and their side effects.

[edit] Hypertrophic Cardiomyopathy.

Patients with hypertrophic cardiomyopathy and an outflow gradient may benefit from atrioventricular (AV) sequential pacing, with improvement in symptoms and a decrease in the outflow gradient.^[10] For those patients with hypertrophic cardiomyopathy and outflow tract obstruction that are not improved by medical or pacing therapy, septal myectomy may be indicated. This surgical procedure is characterized by the removal of a portion of the ventricular septum. Patients with hypertrophic cardiomyopathy may also undergo mitral valve replacement. This prevents mitral regurgitation and the anterior movement of the mitral leaflet that is associated with the left ventricular outflow tract obstruction.

[edit] Pericardial Disease.

Pericardial effusions associated with tamponade may be drained, which results in immediate and dramatic improvement in the patient. The fluid removed must be carefully examined to determine the etiology of the effusion so that it may be appropriately treated to prevent recurrence. If no etiology is identified, antiinflammatory medications may be of benefit.

Surgery for pericardial constriction is virtually always of benefit. The degree of benefit depends on the magnitude of adherence of the pericardial surface to the epicardial surface. Some pericardial constrictions are as easy to remove as an orange peel, whereas others must be painstakingly chiseled from the heart. One must remember that a pericardiectomy is, in fact, only a release of the anterior pericardium between the vagus nerves, since the posterior pericardium cannot be reached.

[edit] Pharmacologic Therapy

The pharmacologic treatment for heart failure is covered in Chapter 65 . There are several caveats to be observed. Diuretics may be harmful to individuals with small or fixed stroke volumes. This is the case for patients with hypertrophic cardiomyopathy, restrictive cardiomyopathy, pericardial effusion with tamponade, and constrictive pericarditis. Careful attention must be paid to excessive diuresis characterized by decreased cerebral or renal perfusion. Diuretics can be used in all forms of congestive heart failure in which the patient has peripheral, pulmonary, or hepatic venous congestion. The extent to which diuretics may be beneficial depends on the pathophysiology of the condition as noted in earlier sections of this chapter.

Vasodilators are potentially dangerous to patients with hypertrophic cardiomyopathy or pericardial disease. This is particularly the case with hypertrophic cardiomyopathy, in which afterload reduction may exacerbate the hyperdynamic contractility, outflow tract obstruction, and the associated predisposition toward syncope or presyncope.

β-Blockers may be useful for patients with hypertrophic or dilated cardiomyopathy. β-Blockers with intrinsic agonist activity should be avoided. Carvedilol, a nonspecific β-blocker with α-blocking properties, is now available for patients with dilated cardiomyopathy and stable, symptomatic heart failure.

Positive inotropic agents are of limited benefit to those with dilated cardiomyopathy, restrictive cardiomyopathy, or constrictive pericarditis. Positive inotropic agents are contraindicated for patients with hypertrophic cardiomyopathy where hypercontractility already characterizes the condition. The only exceptions are in patients with atrial fibrillation and hypertrophic cardiomyopathy, when digoxin may be utilized for rate control, and in advanced states of the condition, when patients develop systolic dysfunction and should be treated more like a dilated cardiomyopathy.

Patients with dilated cardiomyopathy are at risk for developing systemic and pulmonary emboli. Patients with any form of myocardial or pericardial disease may develop atrial fibrillation and may similarly be at risk for emboli, particularly if they have heart failure. Therefore patients with myocardial disease and atrial fibrillation or dilated cardiomyopathy with an ejection fraction below 30% should receive anticoagulants unless there is a contraindication.

Atrial fibrillation is commonly seen in patients with cardiomyopathy and pericardial disease. Patients with myocardial disease who develop atrial fibrillation have a significant decrease in their cardiac output due to the increased heart rate, decreased diastolic filling time, and lack of atrial systolic preloading of the ventricle before contraction. Control of rapid ventricular response in atrial fibrillation and conversion to sinus rhythm are important objectives for patients with myocardial or pericardial disease. Those with myocardial diseases, particularly dilated cardiomyopathy and hypertrophic cardiomyopathy, are markedly prone to ventricular dysrhythmias, including ventricular tachycardia, and are at risk for sudden death. There is as yet no convincing evidence to indicate that pharmacologic treatment of ventricular dysrhythmias prolongs survival in patients with dilated, hypertrophic, or restrictive cardiomyopathy. Nonetheless, for survivors of sudden death, an automatic implantable cardioverter defibrillator (AICD) is indicated. For patients with nonsustained ventricular tachycardia, serious consideration must be given to prophylactic treatment with drugs or devices. Electrophysiologic testing is of prognostic value in patients with ischemic cardiomyopathy. Patients who are inducible should undergo AICD placement.^[11] For those patients who are noninducible yet symptomatic, β-blockers and amiodarone appear to be the most efficacious and least risky drugs. Antidysrhythmic drugs other than β-blockers and amiodarone in patients with ischemic cardiomyopathy are associated with increased mortality and should be avoided.^[12][13]

[edit] Hypertrophic Cardiomyopathy.

Negative inotropic agents, including β-blockers, calcium blockers, and disopyramide, improve symptoms in patients with hypertrophic cardiomyopathy. β-Blockers and calcium channel blockers, especially verapamil, decrease intrinsic heart rate, which allows greater ventricular filling and improved stroke volume. These agents also decrease the hypercontractility characteristic of this disorder, which may diminish the outflow tract gradient, angina, presyncope, syncope, and excessive fatigability.

[edit] Restrictive Cardiomyopathy.

The symptoms caused by restrictive cardiomyopathy are difficult to treat. Careful use of low-dose diuretics and vasodilators may be of some benefit. Negative inotropic agents will be of no benefit to patients with restrictive cardiomyopathy. In fact, these agents may be harmful due to depression of the contractility necessary to maintain reasonable forward perfusion. Digoxin should be used with caution in patients with amyloid heart disease, since these patients appear to be particularly sensitive.

Specific treatment of the various causes of dilated and restrictive cardiomyopathy is beyond the scope of this chapter. Careful consideration must be given to the pros and cons of treatment of disorders such as myocarditis or ischemic cardiomyopathy. Consultation with a cardiologist is appropriate.

[edit] Pericardial Disease.

The first step in the management of acute pericarditis is bed rest. The pain often responds to nonsteroidal antiinflammatory drugs (NSAID) such as ibuprofen. If the pain is severe and does not quickly respond to NSAID, corticosteroids may be efficacious. Large doses, such as 30 mg of prednisone twice daily, are typically used and tapered over 1 month. Colchicine, 1 mg per day, may be of benefit for those patients with recurrent episodes of acute pericarditis.^[14]

[edit] Consultation

Consultation with a cardiologist should be sought for patients with newly diagnosed cardiomyopathies. Patients with New York Heart Association class III and IV symptoms of heart failure should be referred to a cardiologist with expertise in heart failure and a connection to a heart transplant program. Those patients with symptomatic dysrhythmias or sudden death should be seen and treated by an electrophysiologist. Recurrent pericarditis should be evaluated and treated by a cardiologist. Similarly, a cardiologist should help differentiate restrictive cardiomyopathy from constrictive pericarditis.

[edit] SPECIAL ISSUES

The management of patients with a cardiomyopathy is challenging. Patients must be seen frequently, especially when medications are changed or the patient has significant congestion. Patients who are symptomatic at rest, as well as those with unstable angina, syncope, or symptomatic palpitations, should be hospitalized. Disease management using a team approach may be of benefit to those patients with New York Heart Association class III and IV symptoms.^[15] Special emphasis must be placed on compliance, education, and the management of comorbidities such as hypertension, diabetes, and hyperlipidemia.

Patients with hypertrophic cardiomyopathy should refrain from competitive athletics.^[16]

Patients with renal dysfunction represent a particular problem. Angiotensin-converting enzyme inhibitors may be difficult to use in these patients and require careful monitoring. A rising creatinine may indicate inadequate renal perfusion, due to poor stroke volume, or dehydration, due to excessive diuretic use. Evidence of congestion is usually seen in the former, whereas patients with the latter look dry. In some patients, a right heart catheterization may be needed to differentiate low stroke volume from dehydration.

[edit] EVIDENCE-BASED MEDICINE

The primary source for this chapter was MEDLINE. Electronic searches dating back to 1985 were conducted in November 1998. They focused on identifying reviews and large randomized trials.

[edit] REFERENCES