Cardiomyopathies are the third most prevalent form of heart disease in the United States. Cardiomyopathies alter cardiac structure, myocardial function, and/or electrical conduction. Primary cardiomyopathies principally affect the myocardium and secondary cardiomyopathies are associated with other specific systemic disorders. Cardiomyopathies can be further categorized by systolic and/or diastolic dysfunction.
PRIMARY CARDIOMYOPATHIES WITH SYSTOLIC AND DIASTOLIC DYSFUNCTION
Dilated cardiomyopathy is the most common type of cardiomyopathy overall and is usually idiopathic, but may be familial or associated with specific associated causes. Peripartum cardiomyopathy is a form of dilated cardiomyopathy that affects pregnant women from 20 weeks gestation into the postpartum period. Idiopathic dilated cardiomyopathy is characterized by systolic and diastolic dysfunction and is the primary indication for cardiac transplant in the United States.
Most patients with dilated cardiomyopathy present with signs and symptoms of acute heart failure from systolic pump dysfunction. Symptoms include dyspnea on exertion, orthopnea, and paroxysmal nocturnal dyspnea. Physical findings include rales, dependent edema, an enlarged liver, and a holosystolic murmur. Patients may also present with chest pain which may be a function of limited coronary vascular reserve.
Diagnosis and Differential
Typical chest radiograph and electrocardiogram (ECG) findings can be helpful, but the definitive diagnosis is typically made by echocardiogram. Chest radiographs usually show an enlarged cardiac silhouette, biventricular enlargement, and pulmonary vascular congestion. The ECG often shows left ventricular hypertrophy, left atrial enlargement, Q or QS waves, and poor R wave progression across the precordium. The diagnostic echocardiogram shows a decreased ejection fraction, ventricular enlargement, and increased systolic and diastolic volumes. The differential diagnosis includes acute myocardial infarction, restrictive pericarditis, acute valvular disruption, sepsis, or any other condition that results in a low cardiac output state.
Emergency Department Care and Disposition
Patients with symptomatic or newly diagnosed dilated cardiomyopathy typically require admission to a monitored bed or intensive care unit depending on severity of presentation. Patients with known dilated cardiomyopathy benefit from identification of an underlying cause for an exacerbation, including myocardial ischemia, anemia, infection, new-onset atrial fibrillation, bradydysrhythmia, valvular insufficiency, renal dysfunction, pulmonary embolism, or thyroid dysfunction.
Establish intravenous access, provide supplemental oxygen, and initiate cardiac monitoring.
Standard therapies for the treatment of acuteheart failure should be employed. Guidelines from the American College of Cardiology that include issues important for the management of heart failure are available online at http://www.cardiosource.org/Science-And-Quality/Practice-Guidelines-and-Quality-Standards.aspx.
Complex ventricular ectopy can be treated with amiodarone 150 mg IV over 10 min and then 1 mg/min for 6 hours.
Chronic therapy includes diuretics and digoxin, which improve symptoms but have not been shown to impact survival. Angiotensin-converting enzyme (ACE) inhibitors and blockers, such as carvedilol, are often used as they have been shown to improve patient survival.
A growing subset ...