You are in: eMedicine Specialties > Radiology > CARDIAC Cardiomyopathy, DilatedArticle Last Updated: Aug 9, 2007AUTHOR AND EDITOR INFORMATIONSection 1 of 12
  Author: Haroon R Afridi, MBBS, Consulting Staff, Department of Interventional Radiology, King George and Oldchurch Hospital Haroon R Afridi is a member of the following medical societies: American College of Radiology Coauthor(s): George G Hartnell, MD, Professor of Radiology, Tufts University School of Medicine, Director of Cardiovascular and Interventional Radiology, Department of Radiology, Baystate Medical Center Editors: Justin D Pearlman, MD, ME, PhD, MA, Director of Dartmouth Advanced Imaging Center, Professor of Medicine, Professor of Radiology, Adjunct Professor, Thayer Bioengineering and Computer Science, Dartmouth-Hitchcock Medical Center; Bernard D Coombs, MB, ChB, PhD, Consulting Staff, Department of Specialist Rehabilitation Services, Hutt Valley District Health Board, New Zealand; Robert M Krasny, MD, Consulting Staff, Department of Radiology, The Angeles Clinic and Research Institute; Eugene C Lin, MD, Consulting Staff, Department of Radiology, Virginia Mason Medical Center Author and Editor Disclosure Synonyms and related keywords: dilated cardiomyopathy, idiopathic dilated cardiomyopathy, congestive cardiomyopathy, dilated cardiomyopathy, ischemic cardiomyopathy, diabetic cardiomyopathy, alcoholic cardiomyopathy INTRODUCTIONSection 2 of 12
  BackgroundThe World Health Organization (WHO) defines dilated cardiomyopathy as a condition in which the ventricular chambers exhibit increased diastolic and systolic volume and a low (<40%) ejection fraction.1, 2 In the WHO/International Society and Federation of Cardiology classification, dilated cardiomyopathy in its primary (eg, idiopathic or familial) and secondary forms is the most common cause of the clinical syndrome of chronic heart failure. The prevalence of heart failure is approximately 1-1.5% in the adult population of Western countries (see Causes of dilated and specific cardiomyopathies). Dilated cardiomyopathy is associated with a large number of systemic or cardiac diseases, including specific heart muscle diseases (eg, ischemic cardiomyopathy, diabetic cardiomyopathy, alcoholic cardiomyopathy). Dilated cardiomyopathy comprises approximately 90% of all cardiomyopathies; approximately 25% of all cases of dilated cardiomyopathy are of unknown etiology.3 Despite improved treatment, the mortality rate for dilated cardiomyopathy remains high, with a median period of survival of 1.7 years for men and 3.2 years for women. The natural history of the condition is progressive, and its cost, disability, and morbidity are among the highest of any disease.4, 5, 6 For excellent patient education resources, visit eMedicine's Heart Center, Immune System Center, and Blood and Lymphatic System Center. Also, see eMedicine's patient education articles Atrial Fibrillation, Lupus (Systemic Lupus Erythematosus), Alcoholism, Sickle Cell Crisis, and Growth Failure in Children. PathophysiologyDecreased contractility is the hallmark of failing human hearts. In idiopathic dilated cardiomyopathy, this most likely is caused by myocardial cell loss or by changes in the gene expression of proteins responsible for the regulation of muscle contraction.7, 8 This process occurs at 2 levels. That is, the heart's intrinsic mechanisms for sustaining a reasonable ejection fraction begin to fail (eg, contractile proteins and excitation-contraction coupling mechanisms, cell remodeling, bioenergetics), with the problem compounded by the effects of endogenous bioactive chemicals (eg, hormones, neurotransmitters, cytokines). Dilated cardiomyopathy is usually characterized by ventricular dilatation, initially usually of the left ventricle (LV), with myocyte hypertrophy and diminished systolic function. Remodeling occurs with normal or reduced wall thickness, although total cardiac mass is increased. Consequences of failing systolic function include a reduction in ejection fraction, reduced stroke volume (unless valvular regurgitation is present), and increased chamber size. To maintain cardiac output, diastolic ventricular filling is increased, with an increase in end-diastolic pressure. Wall stress increases as the ventricle dilates, thus increasing the amount of cardiac work required to maintain output. As the ventricle dilates, atrioventricular valve regurgitation develops because of stretching of the valve rings. Etiology Dilated cardiomyopathy can be classified broadly into the following 2 types:
Current theories postulate that molecular mechanisms resulting from altered gene expression are the cause of idiopathic cardiomyopathy. These can be categorized broadly into 3 general categories: single gene defects, polymorphic variation in modifier genes, and maladaptive regulated expression of nondefective genes. Specific cardiomyopathies can be caused by direct toxicity; overwork resulting from high cardiac output, as in thyrotoxicosis, pregnancy, and severe anemia; or overwork resulting from increased strain, as in hypertension, valvular regurgitation, or stenosis. The range of causes in adults is different from that in children, although some overlap exists. Causes of dilated and specific cardiomyopathies can be summarized as follows:
Causes of dilated and specific cardiomyopathy in children can be summarized as follows:
FrequencyUnited StatesThe reported incidence of dilated cardiomyopathy varies annually from approximately 5 cases to 8 cases per 100,000 population. However, the frequency is likely underestimated owing to underreporting or underdetection of asymptomatic patients, which may occur in as many as 50-60% of cases. The age-adjusted prevalence in the United States averages 36 cases per 100,000 population.9, 10, 11 InternationalIn Western countries, 1-1.5% of the adult population has dilated cardiomyopathy. Mortality/MorbidityDilated cardiomyopathy accounts for 10,000 deaths annually in the United States.9, 10, 11 Mortality rates are highest in older persons, men, and blacks (Framingham Heart Study, National Heart, Lung and Blood Institute).
RaceCompared with whites, African Americans have an almost 3-fold greater risk of developing dilated cardiomyopathy. This increased risk is not explained by differences in hypertension, cigarette smoking, alcohol use, or socioeconomic factors. Moreover, African Americans have approximately a 1.5- to 2-fold higher risk of dying from dilated cardiomyopathy than age-matched whites. Although the reasons for these differences are not entirely understood, several potential explanations include differences in the number of risk factors for heart failure, as well as differences in the etiology of heart failure, in the response to medical treatment, and in the access to medical care. SexThere are no available statistics regarding the incidence of dilated cardiomyopathy in males versus females. However, in general, heart failure is more common in men. The overall effect of gender on the prognosis of heart failure is not yet clear, largely because many of the early clinical heart failure trials consisted predominantly of male patients.
AgeAge distribution depends on the age distribution of any underlying disease. However, advancing age is reported as an independent risk factor for mortality in several studies.15, 16 Clinical DetailsDyspnea secondary to volume overload is usually the predominant presentation, although features of low cardiac output may predominate. Other presentations range from atrial or ventricular arrhythmias to angina with healthy coronary arteries to sudden cardiac death. Dyspnea may be accompanied by orthopnea, hypotension, fatigue, malabsorption, peripheral edema, ascites, and anorexia. Thromboembolism is common. A family history may provide major clues regarding etiology and prognosis. A substantial number of patients with left ventricular systolic dysfunction (as shown on echocardiography, indicating early dilated cardiomyopathy) may be asymptomatic.17 Preferred ExaminationEvaluation of dilated cardiomyopathy is directed toward identifying causes, some of which may be treatable, and toward assessing cardiac function and detecting complications. Nonimaging investigations include a complete blood count determination, urinalysis, electrolyte analysis, serum albumin measurement, and analysis of thyroid-stimulating hormone levels. Additional specific laboratory studies may be performed if a certain type of dilated cardiomyopathy is suggested. For example, iron studies may be ordered in cases of hemochromatosis, and specific antibody assays may be useful in systemic lupus erythematosus and sarcoidosis. Almost all patients with congestive heart failure resulting from dilated cardiomyopathy have electrocardiogram (ECG) abnormalities. Currently available radiologic investigations are as varied in technique and sophistication as they are in cost. Studies vary from the noninvasive to the invasive and from the dynamic to the static. Radiologic tests are used to help make a diagnosis, to assess the degree of cardiac dysfunction, to identify a cause (though this is unusual), and to guide therapy. It is difficult to make an accurate clinical identification of heart failure resulting from poor ventricular function, but it is important to do so because of the need to relieve symptoms. A substantial number of patients with heart failure have normal ECG results.18 In other patients with apparent heart failure, echocardiography provides extra information on the nature of the cardiac disease that affects management.19 In addition, providing appropriate treatment is important in patients affected more severely (ejection fraction <35-40%), in whom treatment can significantly reduce the mortality rate.12 The initial chest radiograph should usually be followed by echocardiography. These studies may be the only investigations required, and this approach is by far the most common method for diagnosing dilated cardiomyopathy. Subsequent evaluation of cardiac function may be performed by using cine computed tomography (CT) scanning (in rare cases), nuclear scintigraphy, or magnetic resonance imaging (MRI). MRI also is rarely used to diagnose or investigate dilated cardiomyopathy, because the information obtained during echocardiography is often adequate. Although MRI has a valuable role in the diagnosis of specific causes of dilated cardiomyopathy (eg, myocarditis, sarcoidosis, hemochromatosis), the expertise required to evaluate these conditions is not widely available. Limitations of TechniquesChest radiography is good for assessing the effects of cardiac dysfunction on pulmonary perfusion and the development of pulmonary edema. Radiographs seldom help in identifying the etiology of the dysfunction. Echocardiography is an excellent method for assessing cardiac function, determining the presence of valve lesions, detecting complications such as thrombus or pericardial effusion, and assessing response to treatment. Echocardiography may be limited in 10-20% of patients by restricted acoustic access and is dependent on operator experience. Cine CT scanning and CT angiography scanning require radiation and intravenous contrast enhancement; therefore, these techniques are seldom used. Nuclear scintigraphy is a repeatable technique that often is used when serial examination of cardiac function is required. It is not as valuable as echocardiography, since it provides little anatomic information. MRI and magnetic resonance angiography (MRA) are the most accurate methods for assessing cardiac anatomy or function. MRI/MRA is used when echocardiography is inadequate, but this study is often not used because of its relatively high cost and limited availability, as well as contraindications if ferromagnetic metallic foreign bodies are present in the patient. DIFFERENTIALSSection 3 of 12
Aortic Stenosis Cardiomyopathy, Restrictive Congestive Heart Failure Other Problems to Be ConsideredMultiple valvular disease of the heart
RADIOGRAPHSection 4 of 12
FindingsDespite the development of cross-sectional imaging techniques, chest radiography remains useful in evaluating cardiac disease. Radiography is inexpensive and poses low risk to the patient. Moreover, it may provide useful information in guiding further investigations. If the presenting symptom is dyspnea, radiographic findings may differentiate cardiac etiologies (eg, alcoholic cardiomyopathy [see Images 1-3]) from pulmonary ones. Cardiomegaly (cardiac shadow >50% of thorax width on the posteroanterior view), Kerley B lines (prominent lines in the peripheral parts of the lungs, secondary to interstitial edema [see Image 4]), pleural effusions, and cephalization of the pulmonary vasculature (see Image 5) are consistent with a cardiac origin of dyspnea. The pattern of cardiac and great vessel enlargement, as well as of alveolar shadowing, may indicate an etiology. In dilated cardiomyopathy, nonspecific cardiomegaly is usually found, with dilatation of the superior vena cava (see Image 6) and the azygos vein.20 Development of cardiomegaly is easily tracked using chest radiography and is associated with a worse prognosis (see Images 6-7). Although coronary artery calcification may be a clue to ischemic pathology, it is infrequently identified. Degree of ConfidenceChest radiograph is a good method to detect a large heart and pulmonary vascular changes in heart failure; however, it often provides little information on etiology, on the degree of cardiac dysfunction, on complicating factors such as valve dysfunction, or on pericardial effusion. For this reason, radiography is usually augmented with a cross-sectional imaging test, usually echocardiography. CT SCANSection 5 of 12
FindingsAlthough ultrafast CT scanners (electron beam) and multidetector-row CT scanners (see Image 8) can be used with ECG gating to assess ventricular function, little reason exists to employ this equipment. CT scanners require ionizing radiation and injection of relatively large amounts of iodinated contrast agents. Degree of ConfidenceGated CT scanning is an accurate means of evaluating cardiac function, especially with the use of ultrafast CT scanning and 50-millisecond image acquisition. Only 1 short breath-hold period is required, and definition of the endocardial margins is excellent, allowing a degree of automation for defining the ventricular volumes. However, coverage of the entire heart may be difficult. MRISection 6 of 12
FindingsMRI and MRA offer excellent noninvasive means of displaying cardiac and coronary anatomy. They provide high spatial and contrast resolution, which can be used to evaluate congenital and acquired abnormalities and assess results of therapy. Pulse sequences (eg, cine MRA sequences) that provide high temporal resolution can be used to identify and quantify functional abnormalities. Contraindications Contraindications to cardiac MRI are identical to MRI contraindications at any other anatomic site. They include the presence of a pacemaker or other implanted electrical stimulator, ferromagnetic material in the eye, or intracerebral aneurysm clips. Except for the pre-6000 series of Starr-Edwards valves (few of which, if any, exist), no cardiac valve prostheses are a contraindication at the magnetic strengths (<2 T) currently used for diagnostic MRI.5 Retained pacemaker wires, surgical clips, and wire sternal sutures are not contraindications to MRI.21 Coronary and pulmonary artery stents may be imaged safely, although some authors believe it prudent to exclude patients with new (<6-wk-old) stents from MRI. Pregnancy is a relative contraindication. If MRI is necessary, the unknown risk to the fetus must be weighed against the benefit to the mother. Gadolinium-based contrast agents (gadopentetate dimeglumine [Magnevist], gadobenate dimeglumine [MultiHance], gadodiamide [Omniscan], gadoversetamide [OptiMARK], gadoteridol [ProHance]) have recently been linked to the development of nephrogenic systemic fibrosis (NSF) or nephrogenic fibrosing dermopathy (NFD). For more information, see the eMedicine topic Nephrogenic Fibrosing Dermopathy. The disease has occurred in patients with moderate to end-stage renal disease after being given a gadolinium-based contrast agent to enhance MRI or MRA scans. As of late December 2006, the Food and Drug Administration had received reports of 90 such cases. Worldwide, over 200 cases have been reported, according to the FDA. NSF/NFD is a debilitating and sometimes fatal disease. Characteristics include red or dark patches on the skin; burning, itching, swelling, hardening, and tightening of the skin; yellow spots on the whites of the eyes;jointstiffness with trouble moving or straightening the arms, hands, legs, or feet; pain deep in the hip bones or ribs; and muscle weakness. For more information, see the FDA Public Health Advisory or Medscape. Technique MRI of the heart requires an adequate ECG tracing to provide a gating signal for image acquisition at the same part of the cardiac cycle, although some newer sequences (such as true fast imaging with steady-state free precession) are fast enough to be implemented without gating.22 The quality of the examination probably depends more on this parameter than on any other. The effects of strong magnetic fields on the character of the ECG tracing are unpredictable and may compromise gating. The hydromagnetic effect of blood flowing in a strong magnetic field may distort the ECG trace and make ECG gating difficult or impossible. Spin-echo MRI has long been used as an accurate method for assessing cardiac dimensions. Phantom studies have shown a high degree of correlation, which is superior to that of other non-MRI techniques. Spin-echo MRI is the most accurate method for assessing cardiac dimensions, but it is time consuming and provides only static information.23 Evaluation of cardiac function is improved with cine MRA. For this, either breath-hold or non–breath-hold techniques can be used.22 Left ventricular function is optimally evaluated in the following 3 planes:
Once the right anterior oblique equivalent and long-axis 4-chamber equivalents are acquired, they can be used to set up short-axis acquisitions. Usually, the authors acquire the images one third and two thirds of the distance between the mitral valve annulus and the apex of the LV, although contiguous sections can be acquired, if necessary, for accurate assessment of left ventricular mass and volume. A variety of mathematical models can be used to derive ventricular dimensions from long-axis views when time is more important than extreme accuracy for measuring volume and mass (see Image 11).24 For most clinical purposes, the accuracy of long-axis methods compares well with alternative non-MRI techniques.23 Long-axis views also show signal voids resulting from mitral regurgitation and may be used to assess aortic regurgitation. Short-axis views usually provide better definition of the endocardium, with higher intraluminal signal intensity and a good assessment of septal, inferior, and posterior wall function. Software to automatically calculate ejection fractions and ventricular volumes from data on the images is available. Breath-hold tagging sequences have been developed (see Images 14-15). The use of linear or cross tags enhances appreciation of subtle regional wall motion abnormalities.25, 26 Cardiac MRI is excellent for assessing cardiac function in dilated cardiomyopathy because of the high intrinsic contrast between blood and myocardium, especially on cine MRA.27 Cine MRA is a repeatable examination, as compared with echocardiography, with less risk of intertest variation resulting from differences in operator or technique.28 Cine MRA is especially suitable for evaluating the right ventricle, which is difficult to reliably image with other techniques.29 Multilevel cine MRA is the most accurate method for assessing cardiac function and dimensions.30 In addition to providing a means of assessing cardiac function, signal abnormalities may indicate a metabolic or inflammatory etiology for dilated cardiomyopathy (see Image 16).31, 32 In some patients, endocardial surfaces may be defined poorly or intraluminal signal may be lost, as in areas with a slow flow related to ventricular dyskinesia. This may occur especially on long-axis views, which increase the likelihood of in-plane signal saturation. This problem can be overcome by using intravenous contrast media (eg, gadolinium diethylenetriamine pentaacetic acid), which increase signal intensity for up to 20 minutes.33 However, this technique reduces the extent of any flow void resulting from valve regurgitation. Findings Causes of abnormal myocardial signal intensity on T1-weighted images include the following34:
Causes of high myocardial signal on T2-weighted images include the following:
Degree of ConfidenceCurrently, cine MRA is well established as the most accurate modality (some refer to it as the criterion standard) for validating other imaging techniques and for evaluating the effects of medical therapy on ventricular function.35, 36 MRA can be used to assess cardiac dimensions and systolic function, and phase-contrast techniques can be used to evaluate diastolic dysfunction.37 Provided ECG gating and breath-holding are effective, reliable and accurate imaging of cardiac function and anatomy is typical. ULTRASOUNDSection 7 of 12
FindingsEchocardiography is the next and, usually, most useful investigation after chest radiography. Echocardiograms are useful for excluding other causes of a large heart shadow, such as pericardial effusion or multiple valve disease. In dilated cardiomyopathy, all of the heart chambers are typically dilated, and both ventricles are diffusely hypokinetic (see Images 17-18). A feature that may help distinguish idiopathic dilated cardiomyopathy from ischemic cardiomyopathy is the presence of global, rather than regional, dysfunction. However, in some patients with dilated cardiomyopathy, regional dysfunction may be seen as a result of the preservation of systolic function at the base of the LV or the presence of left bundle branch block, which causes paradoxical septal motion. Right ventricular function often is relatively preserved in ischemic cardiomyopathy. Ventricular walls may be normal, increased, or decreased in thickness. The left atrium usually is dilated early on, while right ventricular and right atrial enlargement occur later. The most precise left ventricular cavity and wall-thickness measurements at end diastole, end systole, and ejection fraction are obtained by using M-mode echocardiography, which has the best temporal resolution of any imaging technique (see Image 19). Measurements obtained in a standardized way (at the tips of the mitral valve leaflets) are important to allow for useful comparison with published reference values (see Images 14-15). Two-dimensional echocardiography, with its superior spatial coverage, is used to guide the positioning of the M-mode sample for direct measurements of ventricular wall thickness, left ventricular volumes, and ejection fraction. An advantage of 2-dimensional echocardiography (compared with M-mode imaging) is that the myocardial mass, chamber volumes, and ejection fraction of an abnormally shaped ventricle can be measured. However, because of the subjective nature of 2-dimensional echo examination, its risk of error is higher than that of other cross-sectional imaging techniques. In most patients, images of the mitral and tricuspid valves appear normal but with an abnormally central position with nearly equal excursion of the anterior and posterior leaflets (see Image 20). Significant atrioventricular regurgitation may occur because of incomplete closure of the mitral and tricuspid leaflets as a result of annular dilatation (see Images 21-22). The motion of the mitral valve may reflect the high diastolic pressure, with early opening of the valve leaflets appreciated on M-mode echo (so-called C-hump) (see Image 23). Pericardial effusions are common, but they tend to be relatively small and do not cause significant hemodynamic problems. Mural thrombi may be seen in dilated chambers, especially those with severe hypokinesia (see Image 24). Degree of ConfidenceThe degree of confidence is high. NUCLEAR MEDICINESection 8 of 12
FindingsThe most important contribution of nuclear cardiology is the ability to assess myocardial perfusion and ventricular function. Nuclear ventriculography is a reliable and reproducible method for assessing left ventricular function, an especially important consideration when one performs sequential studies to assess the effects of therapy.38, 39 Radionuclide ventriculography (multiple-gated acquisition or first-pass scanning) is used to estimate ventricular size and ejection fraction and to assess wall motion abnormalities (see Images 26-29). Diastolic dysfunction and the response to exercise also can be reliably evaluated.39, 40 In idiopathic dilated cardiomyopathy, the global ejection fraction is decreased and wall motion is uniformly poor, with the exception of possible sparing of the septal and anterior basal segments. Radionuclide perfusion imaging can help in differentiating ischemic causes and other etiologies. A perfusion defect of greater than 40% strongly suggests ischemic etiology. Unfortunately, large and fixed (especially apical) perfusion defects have been reported in dilated cardiomyopathy.41 Radionuclide ventriculography is frequently used to follow the cardiotoxic effects of drugs (eg, doxorubicin) that cause cardiomyopathy. Dilated cardiomyopathy caused by doxorubicin usually produces severe, irreversible left ventricular dysfunction symptoms of congestive heart failure; therefore, it is essential to detect ventricular dysfunction early, well before any irreversible changes occur. Because radionuclide ventriculography is a reproducible technique, it is used widely for this purpose.42 The technique can also be used to assess the response to therapy in patients with any form of idiopathic cardiomyopathy. Gated single-photon emission CT (SPECT) has been used to successfully identify etiologies of dilated cardiomyopathy, because of its ability to depict myocardial perfusion and function. Myocardial perfusion and function imaging has been used to accurately classify cardiomyopathies as ischemic or nonischemic, depending on the gated SPECT and perfusion images.43 Ischemic cardiomyopathies tend to have reversible or fixed perfusion defects along with regional wall motion abnormalities on gated SPECT, while nonischemic cardiomyopathies demonstrate mild perfusion defects with diffuse wall motion abnormalities. Degree of ConfidenceThe degree of confidence is high. Nuclear ventriculography is a relatively accurate and repeatable method for assessing left ventricular function. It has been used for longitudinal studies to assess the response to medical treatment and to detect early changes resulting from drug toxicity, which may lead to dilated cardiomyopathy in patients undergoing chemotherapy with anthracycline cytotoxic agents. ANGIOGRAPHYSection 9 of 12
FindingsDetermining ischemic heart disease as a cause of cardiomyopathy is important because it may help in identifying treatable pathology. Coronary angiography remains the best technique for assessing epicardial coronary artery disease and for determining whether revascularization can potentially reverse the cardiomyopathy. Multiple studies of patients with symptomatic heart failure, coronary artery disease suitable for revascularization, and poor systolic function (with or without angina) have demonstrated a survival and ventricular function benefit in surgical treatment in comparison with medical therapy. The need for coronary angiography depends on the following factors:
Coronary angiography is performed in multiple projections because it is a projectional technique, and atherosclerotic lesions typically are eccentric. Many groups have correlated the degree of stenosis with ultimate clinical or pathologic outcome. The severity of obstructive disease is assessed in each coronary artery segment by comparing the arterial diameter at a point of maximum lumen reduction with that of a proximal or distal normal-appearing artery. Nonatherosclerotic coronary disease occasionally causes ischemic heart disease. Examples include causes of arteritis (eg, Takayasu disease, giant cell arteritis, polyarteritis nodosa), infections (eg, syphilitic stenoses of the coronary ostia, aortic root abscess), congenital coronary anomalies, and Kawasaki disease.44 During cardiac catheterization, a left ventriculogram usually is obtained to assess the LV, which demonstrates diffuse enlargement and reduced contractility. Abnormalities of segmental wall motion are common, and mural thrombi may be found in the apex. Cine angiography was once regarded as the reference standard for assessing LV function. Currently, this is not the case; as a result of its projectional nature and the need to inject contrast agent, cine angiography may be inaccurate. In particular, it can fail to demonstrate regional wall motion abnormalities. Three-dimensional echo imaging and cine MRA are more accurate in assessing global and regional ventricular function.45 However, a few contraindications to cardiac catheterization have been identified. Degree of ConfidenceThe degree of confidence is high. INTERVENTIONSection 10 of 12
Currently, the mainstay of treatment is the administration of ACE inhibitors in asymptomatic or symptomatic patients and the use of diuretics in patients with volume overload. Digoxin is used in patients who remain symptomatic or have atrial fibrillation. Beta-adrenergic blocking agents are used with increasing frequency in mildly to moderately symptomatic patients and are known to improve left ventricular function, reduce hospitalization, and lower mortality rates. Adjunctive therapy includes the administration of anticoagulants in patients with impaired left ventricular ejection fractions or atrial fibrillation, the administration of amiodarone in patients with symptomatic arrhythmias, and the maintenance of potassium levels in the high-normal range to prevent sudden death. Cardiac transplantation may be offered to patients who have the familial form or who are inadequately treated medically. Discontinuation of cytotoxic therapy may be necessary for anthracycline toxicity. In some centers, ventricular endocardial restoration procedures may be beneficial in patients with dilated cardiomyopathy resulting from extensive anterior myocardial infarction.46 MULTIMEDIASection 11 of 12
REFERENCESSection 12 of 12
| |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
