Question

angiotensin converting enzyme inhibitors are a central part of the treatment of heart failure because they have more than one action to address the pathological changes in this disorder. which of the following pathological changes in heart failure is not addressed by ace inhibitors ?

a. changes in the structure of the left ventricle so that it dilates, hypertrophies, and uses energy less efficiently

b. reduced formation of cross bridges so that contractile force decreases

c. activation of the sympathetic nervous system that increases heart rate and preload

d. decreased renal blood flow that decreases oxygen supply to the kidney

Answer 1

Angiotensin-converting enzyme (ACE) inhibitors are very important medicines for managing heart failure. They relax blood vessels and lower blood pressure. This improves blood flow and decreases the workload of the heart.

ACE inhibitors have the following actions:

• Dilate arteries and veins by blocking angiotensin II formation and inhibiting bradykinin metabolism. This vasodilation reduces arterial pressure, preload and afterload on the heart.
• Down regulate sympathetic adrenergic activity by blocking the facilitating effects of angiotensin II on sympathetic nerve release and reuptake of norepinephrine.
• Promote renal excretion of sodium and water (natriuretic and diuretic effects) by blocking the effects of angiotensin II in the kidney and by blocking angiotensin II stimulation of aldosterone secretion. This reduces blood volume, venous pressure and arterial pressure.
• Inhibit cardiac and vascular remodeling associated with chronic hypertension, heart failure, and myocardial infarction.

Hence, C. Activation of the sympathetic nervous system that increases heart rate and preload. is the correct answer.