Digitalis is obtained from the leaves of Digitalis purpurea. It has positive inotropic effects on the heart by enhancing myocardial activity and contractility. This increases cardiac output and shifts the stroke volume-preload curve towards normal in patients with congestive heart failure (CHF), improving cardiac function and relieving symptoms. Digitalis is used to treat CHF and cardiac arrhythmias, but it has contraindications like tachycardia, hypokalemia, and myocardial infarction.