CONGESTIVE HEART FAILURE: DRUG SELECTION Therapeutic Rationale Reduce salt and water reten

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CONGESTIVE HEART FAILURE: DRUG SELECTION Therapeutic Rationale * Reduce salt and water retention: Diuretics are the first line drugs for use in most uncomplicated cases of congestive heart failure. (Restriction of sodium intake is desirable but sometimes difficult to achieve.) Reduction of blood volume decreases the size of the heart, allowing it to function on a more favorable portion of the ventricular function curve, and reduces the intracapillary pressure that leads to edema. The diuretics are described in more detail in Chapter 13. * Increase the force of cardiac contraction: Positive inotropic drugs such as digitalis glycosides are effective in many cases of chronic failure and move the heart to a higher ventricular function curve. They are generally more toxic than the diuretics. Several positive in- otropic substitutes for digitalis are available for use in special circumstances. * Reduce vascular tone: Vasodilators reduce the work of the heart and improve cardiac ejection and tissue perfusion. They are especially useful in acute failure, eg, that associated with myocar- dial infarction and severe hypertension. Vasodilators are described in greater detail in Chapters 2 and 5. (PgDn key for more text) Major indications * Chronic low output failure: Use an thiazide diuretic , digoxin , and if necessary, a vasodilator combination such as hydralazine (unlabelled use) and isosorbide dinitrate , or captopril . Some patients respond better to captopril than to digoxin as the second line drug. * Acute, severe failure: See Table . Other Indications: * Cardiac arrhythmias: cardiac glycosides are often used in atrial tachycardias, atrial flutter, and atrial fibrillation to control ventricular rate. In the case of flutter and fibrillation, glycosides may also lead to the conversion of the arrhythmia to normal sinus rhythm. References: 1. Arnold SB, et al: Long-term digitalis therapy improves left ventricular function in heart failure. NEJM 1980; 303:1443. 2. Cohn JN (editor): New concepts in the mechanisms and treatment of congestive heart failure (Symposium). Am J Cardiol 1985; 55: 1A. (PgDn key for more references) 3. Cohn JN, et al: Effect of vasodilator therapy on mortality in chronic congestive heart failure. Results of a Veterans Administration Cooperative study. NEJM 1986; 314: 1547. 4. Digitalis. (Symposium) J Am Coll Cardiol 1985; 5: 1A. 5. Doherty JE: Clinical use of digitalis glycosides. An update. Cardiol- ogy 1985; 72:225. 6. Franciosa JA, Dunkman WB, Leddy CL: Hemodynamic effects of vasodilators and long-term response in heart failure. J Am Coll Car- diol 1984; 3: 1521. 7. Jaski BE, et al: Positive inotropic and vasodilator actions of mil- rinone in patients with severe congestive heart failure. Dose response relationships and comparison to nitroprusside. J Clin Invest 1085; 75: 643. 8. Maekawa K, Liang C-S, Hood WB: Comparison of dobutamine and dopamine in acute myocardial infarction. Effects of systemic hemodynamics, plasma catecholamines, blood flows and infarct size. Circulation 1983; 67:750. 9. Smith TW, et al: Digitalis glycosides: Mechanisms and manifestations of toxicity. (in 3 parts) Prog Cardiovasc Dis 1984; 26:413,495; 27:21. (Home to return to top of file)


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