Final answer:
Digitalis is a cardiac glycoside that increases myocardial contraction force and velocity, primarily used to treat heart failure and arrhythmias, especially atrial fibrillation. It works by increasing intracellular calcium in the heart cells, enhancing contractility.
Step-by-step explanation:
A cardiac glycoside commonly used in the treatment of congenital heart failure and arrhythmias is Digitalis. It works by increasing the force and velocity of myocardial contraction. This is known as a positive inotropic effect, which is beneficial in strengthening the heart's pumping ability and regulating heart rate. Digitalis increases intracellular calcium levels by inhibiting the pumping of calcium ions back into the sarcoplasmic reticulum, thus enhancing the contractility of the heart muscle.
In addition to its inotropic properties, Digitalis can help to relieve heart failure symptoms, particularly when the patient isn't responding to ACE inhibitors and diuretics. It also has a specific use in slowing certain types of irregular heartbeat, such as atrial fibrillation, by exerting its effect on the electrical conduction system of the heart.
Other medications that affect cardiac function and are used to manage cardiovascular issues include ß-blockers like metoprolol and propanolol, which block the ß-receptors associated with vasoconstriction and increase in heart rate, consequently improving cardiac function. These medications are typically used in conjunction with therapy for cardiac arrhythmias, as well as treating chest pain (angina).