The heart operates by electrical impulses to circulate blood throughout the body. A group of cells in the atrium of the heart functions as an automatic pacemaker, generating electrical current that powers synchronized contractions of heart muscle. Many factors can cause the heart to beat more rapidly, a condition known as ventricular tachycardia. Calcium channel blockers slow the heartbeat rate and are useful in treating abnormally rapid heart rhythms.
The Heart's Electrical System
The heart's electrical system controls all of the functions that take place when the heart pumps blood. A heartbeat consists of a single cycle in which the heart's chambers alternately relax and contract to pump blood. Each heartbeat is initiated by an electrical signal from within the heart muscle, in the sinoatrial (SA) node in the right atrium. Thus the SA node is known as the heart's natural pacemaker. The SA node generates an electric signal about 60 to 80 times a minute, and each signal results in a heartbeat.
Ventricular Tachycardia
Ventricular tachycardia is a condition in which the heart beats at a more rapid pace than normal. In most cases, ventricular tachycardia is caused by heart disease, such as a previous heart attack, a congenital heart defect, cardiomyopathy, or myocarditis. Sometimes ventricular tachycardia occurs after heart surgery. Ventricular tachycardia can potentially lead to ventricular fibrillation, in which the heart beats so fast and irregularly that the heart is unable to effectively pump blood. Ventricular fibrillation is a leading cause of sudden cardiac death.
Calcium Channel Blockers
According to MayoClinic.com, certain calcium channel blockers such as diltiazem (Cardizem, Cartia, Dilacor, Taztia, Tiazac) and verapamil (Calan, Isoptin, Covera, Verelan) are used to treat people with irregular or fast heartbeats. These drugs help to slow the heart rate by reducing the number of electrical impulses that pass through the atrioventricular (AV) node into the lower heart chambers. They also help to reduce the rate at which calcium moves into the heart and blood vessel walls. This helps to relax the blood vessels, which improves blood flow and makes it easier for the heart to pump blood.
Types of Calcium Channel Blockers
RxList points out that the two basic types of calcium channel blockers are dihydropyridine and non-dihydropyridine. The most significant difference between the two is that non-dihydropyridine calcium channel blockers are able to slow the heart rate, while dihydropyridine calcium channel blockers do not. Therefore, non-dihydropyridine calcium channel blockers such as verapamil and diltiazem are useful for treating ventricular tachycardia.
Side Effects
According to Health.com, each individual drug, verapamil and diltiazem, produces its own side effects, but the most common side effects include flushing, a pounding sensation in the head, dizziness, headache, swelling of the legs, reduced blood pressure, tingling sensations in the extremities, generalized weakness and the increased potential for heart failure.
