What is the purpose of Digitalis in treating heart conditions?

Digitalis is primarily used in the management of certain heart conditions, particularly heart failure and atrial fibrillation. The key action of Digitalis is to increase the force of cardiac contractions. This increased contraction strength arises from its ability to inhibit the sodium-potassium ATPase pump, leading to an increase in intracellular calcium levels, which enhances the heart's ability to pump blood more efficiently.

By improving the contractility of the heart muscle, Digitalis helps to alleviate symptoms of heart failure, such as fatigue and shortness of breath, thereby improving overall cardiac output. This mechanism is vital in the treatment of conditions where the heart's pumping ability is compromised, making option B the accurate choice.

In contrast, while Digitalis may have some effects on heart rate, its primary role is not to decrease heart rate directly. The other options, focusing on blood vessel relaxation and blood volume management, are not primary mechanisms related to Digitalis, as its effects target myocardial contractility rather than vascular dynamics or fluid balance.