What compensatory mechanism is activated in chronic heart failure?

In chronic heart failure, the body activates the neuro-hormonal system as a compensatory mechanism to counteract the decreased cardiac output. This system includes various hormonal responses that aim to maintain blood pressure and improve blood flow to vital organs despite the heart's reduced ability to pump effectively.

Specifically, activation of the sympathetic nervous system leads to increased heart rate and myocardial contractility, while the renin-angiotensin-aldosterone system (RAAS) promotes sodium and water retention to expand blood volume. This helps to temporarily improve perfusion to the kidneys and other organs, even if it eventually contributes to fluid overload and worsens heart failure over time.

The other choices do not accurately represent compensatory mechanisms in chronic heart failure. Increased blood flow to the heart itself is limited by the heart's impaired function. Decreased peripheral resistance is generally not a compensatory response, as in heart failure, the body typically does the opposite, maintaining or increasing peripheral resistance to help preserve perfusion. Improved contractility of the ventricular muscle is also not a natural compensatory response in chronic heart failure; rather, the heart struggles with contractility due to underlying pathologies such as myocardial infarction or cardiomyopathy.