Powered by a synchronized electrical system, the heart normally beats about 60 to 100 times a minute. In atrial fibrillation, however, this electrical system becomes chaotic, causing the heart to beat up to 500 times a minute, increasing the potential for a stroke. Calcium channel blockers reduce the number of the heart's erratic electrical impulses, slowing it down and restoring cardiac equilibrium.
The Heart Operates by Electrical Impulses
The heart's electrical system controls the timing of each heartbeat by sending an electrical signal to specialized cells in the heart. It keeps the heart beating in a regular rhythm and adjusts the rate at which it beats. When the electrical system is working properly, it maintains a normal heart rate and rhythm. The goal of the heart's electrical system is to maintain a normal heart rate of 60 to 100 beats per minute and a normal sinus rhythm, which is the regular normal, synchronized contraction of the atria and ventricles. Problems with this electrical system can cause an arrhythmia, in which the heart chambers beat in a rapid, uncoordinated way, a condition known as atrial fibrillation.
Atrial Fibrillation --- Heartbeats Out of Control
The Mayo Clinic points out that during atrial fibrillation, or AF, the heart's two upper chambers, the atria, beat chaotically and irregularly, out of coordination with the two lower chambers, the ventricles. In AF, the orderly sequence of electrical impulses and synchronized heartbeats is interrupted. As a result, the heart beats faster and irregularly, with the atria contracting up to 500 times a minute, and the ventricles contracting up to 180 times. AF causes poor blood flow to the body, resulting in heart palpitations, shortness of breath and weakness. According to HealthCentral.com, people with AF are five times more likely to have a stroke.
Calcium Channel Blockers Slow Down Arrhythmias
Calcium channel blockers, or CCBs, can be used to treat AF. They help to reduce the heart rate by restricting calcium from entering heart muscle cells, thereby reducing the number of electrical impulses that pass through the heart's AV node into the ventricles. The AV node serves as an electrical relay station between the atria and the ventricles. Calcium is crucial for heart muscle cells because it enables electrical conduction and cell contraction. When surplus calcium is inhibited from entering heart cells, electrical activity is reduced and heart rate is slowed.
Different Types of CCBs
Different CCBs differ in their mechanism of action in the body. CCBs are available in two types: dihydropyridine and non-dihydropyridine. According the Patient UK, dihydropyridine CCBs have little effect on the heart muscle, so are not useful for treating arrhythmias. Non-dihydropyridine calcium channel blockers such as verapamil and diltiazem, however, slow down the heart rate, and are useful for treating AF because they block calcium from going into the conducting cells in the heart, thus slowing the heart rate.
Adverse Side Effects
Side effects of CCBs include a slowed heart rate, flushing, headache or a pounding sensation in the head, dizziness, swelling of the legs, decreased blood pressure, tingling sensations in the arms or legs, or weakness. CCBs commonly result in sexual dysfunction. Diltiazem and verapamil may also cause a skin rash.
