Cardiovascular drugs act on the components of the circulatory system to treat cardiovascular diseases. Cardiac arrhythmiaÑa heartbeat that is too fast, too slow, or has an irregular rhythmÑis treated with drugs to restore the normal rhythmic rate, such as procainamide and quinidine. Digoxin helps patients with heart failure by increasing the force of contraction and pumping of the blood by the heart muscle. Hypertension can be treated with drugs such as quinapril, nifedipine, or propranolol, to lower the blood pressure and reduce the likelihood of damage to the heart and blood vessels. Some of these drugs are also used to treat heart failure since at lower blood pressures the heart can pump blood into the vascular tree more easily. Drugs such as Alteplase dissolve clots in the coronary arteries that cause a heart attack. Anticoagulant drugs such as coumadin and antiplatelet drugs such as aspirin prevent clotting of the blood that could cause a heart attack. Cholesterol level can be lowered with lovastatin and other antihyperlipidemic drugs.