Drugs for Heart Failurec

                                   Fig:  The Failing Heart

ACE  INHIBITORS AND AT-1 ANTAGONISTS :

ACEIs block formation of AII and  inhibit  bradykinin metabolism  decrease aldosterone ->decrease  fluid
retention -> increase  vasodilation -> decrease preload and afterload.

In addition to improving symptoms and exercise tolerance, they slow progression of heart failure and prolong survival. In  addition, ACEIs have  prophylactic value  post-MI because they oppose  "remodeling"  that can lead to heart failure.





                 Fig: Effects Resulting From Inhibition of  Cardiac Membrane Na+/K+ATPase 

The increase in  contractility improves cardiac output,  reversing the compensatory  tachycardia
and the increases  in BP and PVR that occur in heart failure.  Renal perfusion and diuresis are also
improved, providing additional beneficial effects in heart failure. However,  cardiac glycosides do
not improve survival; thus, ACEIs are now considered drugs of first choice in most situations.

Cardiac glycosides exert electrophysiologic  effects on the heart (via PANS) that include central
vagal stimulation, facilitation of muscarink  activity, and sensitization of  baroreceptors. These
effects occur at conventional doses and in the absence of heart failure lead to a decrease in CO
without effects on BP and PVR.


Cardiac Effects of Digitalis
Table the Cardiac Effects of Digitalis

 Table . Properties  of Digoxin