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Explain the treatment options for dilated cardiomyopathies.
The treatment of DCM is essentially the symptomatic management of left-sided heart failure (Table 11.3). Four stages of heart failure are described: initial cardiac injury; neurohormonal activation and cardiac remodeling; fluid retention and peripheral vasoconstriction; and ultimate contractile failure. Mild to moderate heart failure is treated with preventative measures (dietary manipulations, blood pressure control, lowering of serum lipids, weight loss, and cessation of smoking) in combination with progressive pharmacologic interventions. Medications are aimed at antagonizing specific neurohormonal mechanisms of injury and controlling fluid retention. Beneficial classes of drugs include angiotensin-converting enzyme inhibitors (e.g., enalapril, captopril), angiotensin II receptor blocking agents (e.g., losartan), β-blockers (e.g., carvedilol, metoprolol), diuretics (e.g., furosemide), aldosterone antagonists (spironolactone), and digoxin.
Diastolic dysfunction tends to develop as myocardial function deteriorates, resulting in chronically elevated LA pressures and, often, atrial fibrillation. In the patient with severe DCM, the maintenance of sinus rhythm becomes a key factor in maintaining forward cardiac output, so this population is often placed on antiarrhythmic agents, commonly amiodarone. When pharmacologic interven-tions fail to maintain sinus rhythm, dual-chamber (atrio-ventricular sequential) pacemakers are often implanted, for maintenance of the atrial contribution to diastolic ventricular filling.
Ventricular dysrhythmias cause severe decompensation and are potentially fatal. To prevent this, an automatic implantable cardioverter-defibrillator (AICD) is often implanted. As ventricular failure progresses, symptoms become refractory to outpatient medical therapy. Patients may require hospitalization for careful fluid management and administration of positive inotropic, as well as vaso-active agents. At this point, cardiac transplantation is frequently considered. In the interim, maintenance of adequate tissue perfusion may require temporary support with an intra-aortic balloon pump (IABP) or implantation of a left ventricular assist device (LVAD). The use of implantable LVADs has become common management for intractable cardiac failure in patients with end-stage cardiomyopathy who are awaiting transplantation.
A number of experimental surgical procedures (LV reconstruction, dynamic cardiomyoplasty, and others) have been developed to treat end-stage cardiomyopathy, but results to date have been variable. A comprehensive review of surgical treatments for heart failure was recently published by Kumpati et al. (2001).
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