An increase in hea rate and renin release seen in patients of CHF can be overcome by which of the following drugs –
**Core Concept**
The question revolves around the pathophysiology of congestive heart failure (CHF), specifically the body's compensatory mechanisms to increase cardiac output and blood pressure. In CHF, the heart's ability to pump blood is impaired, leading to increased sympathetic tone, renin release, and subsequent vasoconstriction. This results in increased heart rate and blood pressure, attempting to compensate for the decreased cardiac output.
**Why the Correct Answer is Right**
The correct answer is a type of vasodilator that acts on the renin-angiotensin-aldosterone system (RAAS) to reduce blood pressure and heart rate. By inhibiting the conversion of angiotensin I to angiotensin II, these drugs reduce vasoconstriction and renin release, thereby overcoming the body's compensatory mechanisms in CHF. This class of drugs includes ACE inhibitors and ARBs, which block the effects of angiotensin II on the heart and blood vessels.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because beta-blockers, while beneficial in CHF, do not directly address the increased sympathetic tone and renin release. They may even worsen the situation in acute decompensated CHF.
**Option B:** This option is incorrect because diuretics, while essential in CHF, do not directly affect the renin-angiotensin system or the body's compensatory mechanisms.
**Option C:** This option is incorrect because calcium channel blockers may worsen CHF by reducing cardiac contractility and increasing peripheral resistance.
**Clinical Pearl / High-Yield Fact**
In CHF, the body's compensatory mechanisms often lead to increased sympathetic tone and renin release, which can worsen the condition. Blocking the RAAS with ACE inhibitors or ARBs can help overcome these mechanisms and improve cardiac output and blood pressure.
**Correct Answer:** C. Calcium channel blockers may worsen CHF by reducing cardiac contractility and increasing peripheral resistance.