Heart Failure Drugs

what are the kind of drugs that are used to treat heart failure?

diuretics, beta blockers, vasodilators, renin-angiotensin drugs

what class of drugs helps increase CO & reduce sxs in systolic HF?

positive inotropic drugs (digitalis glycosides)

digitalis glycosides are originally derived from

foxglove plant

digitalis glycosides MOA is complex, including

mechanical and autonomic effects

digitalis glycosides mechanical effects

inhibits Na+/K+ pump in cardiac cells; so Na+ accumulates in the cell

as digitalis glycosides mechanical effects increase intracellular Na+, what is extruded less from the cell?

calcium by the Na+/Ca++ exchanger; intracellular Ca++ increases → stronger contraction

digitalis glycosides autonomic effect decreases HR by

stimulating the vagus nerve, inhibiting sympathetics to the heart

problems w/ digitalis glycosides is toxicity, which is fairly common (20-25% hospitalized). Toxicity can occur even if

the serum levels are in normal range (0.5-2 ng/mL)

digitalis glycosides toxicity can be fatal, so look out for sxs of

GI distress, cramping, nausea/vomiting, fatigue, confusion, clinical depression, blurred vision, arrythmias

what other positive inotropes are usually reserved for acute & severe heart failure?

phosphodiesterase inhibitors (inamrinone, milrinone), dopamine/ dobutamine (dobutrex)

phosphodiesterase inhibitors (inamrinone, milrinone) increase myocardial Ca++ by

preventing cAMP breakdown

dopamine/ dobutamine (dobutrex) MOA

stimulate beta-1 receptors on the heart

other positive inotropes are not more effective than digitalis, what is their other limitation?

parenteral administration (IV drip)