Which medication is used to improve the contractility of the heart?

Digoxin is a medication that is specifically used to improve the contractility of the heart. It belongs to a class of drugs known as cardiac glycosides. By increasing the force of the heart's contractions, digoxin enhances cardiac output, which can be particularly beneficial in conditions like heart failure and certain arrhythmias. It achieves this effect by inhibiting the sodium-potassium ATPase pump, leading to an increase in intracellular calcium levels. This mechanism enables the heart muscle to contract more forcefully, improving the efficiency of the heart in pumping blood.

The other medications listed serve different purposes. Lasix, or furosemide, is a diuretic that helps reduce fluid overload but does not directly enhance myocardial contractility. ACE inhibitors primarily help lower blood pressure and reduce the heart's workload by decreasing fluid retention and improving blood flow, but they do not directly increase contractility. Similarly, beta blockers are used to decrease heart rate and workload on the heart, providing benefits in conditions like hypertension and certain types of heart failure, yet they do not improve contractility. Thus, digoxin is uniquely positioned among the options listed as the medication that enhances the heart's contractility.