| ACE Inhibitors and Angiotensin II Receptor Antagonists |
ACE inhibitors, or angiotensin converting enzyme inhibitors (i.e., Enalapril, Captropril) reduce peripheral vascular resistance via blockage of the angiotensin converting enzyme. This action reduces the myocardial oxygen consumption, thereby improving cardiac output and moderating left ventricular and vascular hypertrophy. ACE inhibitors are essential for treatment of CHF due to systolic dysfunction (Garg, AHCPR guidelines). Older people may show an exaggerated drop in blood pressure after the first dose of an ACE inhibitor. Therefore, we give a short-acting ACE inhibitor such as Captropril and have the patient's blood pressure observed for several hours. Longer-acting ACE inhibitors are given when the patient's tolerance to Captropril is established. This is another medication which can lead to hypotension. Use ACE inhibitors with care if the patient is on other drugs with hypotensive potential (e.g., antidepressants). Angiotensin II receptor antagonists, as their name suggests, block the binding of angiotensin II to the AT1 receptor. These drugs to not inhibit kinin metabolism (e.g., bradykinin). Aspirin may reduce the beneficial CHF effects of ACE inhibitors, but apparently does not alter the efficacy of angiotensin II inhibitors in treating CHF. Cough, a not infrequent side effect of ACE inhibitors, has not been seen with angiotensin II receptor blockers. The limited data available at present suggest that angiotensin II receptor blockers and ACE inhibitors have roughly equivalent beneficial effects on symptoms and hemodynamics of patients with CHF. |