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.


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   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.

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   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.


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