Digitalis usually has what effect on exercise tolerance in patients with CHF?

Digitalis, specifically digoxin, is a medication commonly used in the management of chronic heart failure (CHF). One of its primary effects is to enhance the contractility of the heart muscle, which helps improve cardiac output. In patients with CHF, where the heart's ability to pump blood effectively is compromised, improving cardiac output can significantly enhance exercise tolerance.

By enhancing the strength and efficiency of heart contractions, digitalis can help reduce symptoms associated with heart failure, such as fatigue and dyspnea during exertion. As a result, patients might experience an improved ability to engage in physical activities, thereby increasing their overall exercise tolerance. This improved tolerance allows individuals with CHF to participate more actively in rehabilitation programs and daily activities, which is vital for maintaining health and quality of life.

The other considerations related to the impact of digitalis, such as having no change, decreasing it, or completely abolishing exercise tolerance, do not align with the pharmacological effects of the medication when appropriately used in the context of CHF management. Therefore, the enhancing effect of digitalis on exercise tolerance in these patients stands out as the correct response.