Heart Failure Quiz

See Section. Option C is aldosterone’s main renal effect: conserving sodium and thereby retaining water. Aldosterone is a hormone released as part of the renin-angiotensin-aldosterone response when the circulation senses inadequate effective perfusion. It acts in the later parts of the kidney tubule, increasing sodium reabsorption from the forming urine. Retained sodium supports expansion of the fluid outside cells and of circulating volume. This can initially support filling, but in heart failure the extra volume may worsen congestion and breathlessness. Distinguish this volume effect from angiotensin II’s vasoconstriction, which increases the resistance against which the heart pumps.

Reduced sympathetic activity (D) is not the direct effect of aldosterone; the sympathetic response to heart failure generally increases rate and vascular tone. Venous dilation (A) can lower preload, the filling load before contraction, but is not aldosterone’s primary action. Increased sodium excretion (E) is the opposite of aldosterone’s effect and is closer to the volume-reducing action of natriuretic peptides. A direct increase in myocardial contractility (B) would alter muscle force; aldosterone does not simply restore pump strength independently of loading.