Which agent is used as a positive inotropic support in CHF?

• A. Dobutamine
• B. Digoxin
• C. Furosemide
• D. Morphine

Answer: (B)

Increasing the force of heart contractions to raise cardiac output is the goal of positive inotropic support in CHF. Digoxin achieves this by inhibiting the Na+/K+-ATPase pump in cardiac cells, which raises intracellular Na+. This shift reduces the extrusion of Ca2+ via the Na+/Ca2+ exchanger, so more Ca2+ stays inside the cell during systole. The result is stronger, more efficient contractions that help improve stroke volume in systolic heart failure. Digoxin also provides a mild slowing of the heart rate and reduces sympathetic outflow, which can be beneficial in patients who have concurrent atrial fibrillation or rapid ventricular response.

Its effects come on gradually and it carries a narrow therapeutic window, so it’s used for longer-term management rather than immediate stabilization. In contrast, other options either act as rapid, potent inotropes (like dobutamine) to support acute decompensation, or serve other roles such as diuresis (furosemide) or venous dilation and relief of symptoms (morphine). Thus, digoxin is the agent classically associated with positive inotropic support in CHF.