An arrhythmia is an abnormal heart rhythm. The heart has a finely tuned electric system that maintains the heart beating at a regular rhythm. But medicines and certain medical conditions can affect the heart's electrical system, causing an arrhythmia. These abnormal heart rhythms can make the heart beat too fast or too slow, cause skipped beats and, in severe cases, may make the heart stop beating altogether. Excessive intake of caffeine can trigger certain heart arrhythmias.
Types of Arrhythmias
In general, the heart beats between 60 and 80 times a minute, pumping blood throughout the body. The heart's natural pacemaker, called the sinoatrial node, controls these beats. The two types of arrhythmias are ventricular and supraventricular. Ventricular arrhythmias originate in the ventricles, the lower chambers of the heart. Supraventricular arrhythmias start in the electrical circuit above the ventricles, usually around the atria, the upper chambers of the heart. Caffeine may cause supraventricular tachycardia, during which the heart beats faster than usual.
Causes
Caffeine can be a cause of arrhythmias, but this does not usually happen unless a person is sensitive to caffeine's effects. The amount of ingested caffeine necessary to increase heart rate varies from person to person. According to the Cleveland Clinic, other causes of arrhythmias include coronary artery disease, when the arteries that bring blood to the heart get clogged or obstructed; high blood pressure; problems with the heart's valves; heart attacks; and electrolyte imbalances such as high potassium.
Sources of Caffeine
Drinking small amounts of caffeine-containing products may not cause arrhythmias, but if you have heart disease and other conditions that can predispose you to arrhythmias, your physician may advise you not to consume caffeine-containing products such as chocolate, coffee and tea. Caffeine is also present in over-the-counter migraine remedies, diet pills and energy drinks.
Caffeine Effects
According to Discovery Health, caffeine binds to adenosine receptors in neurons, the nerve cells that carry information from the brain to the rest of the body. Adenosine usually slows down nerve conduction, but when caffeine binds to these receptors, nerve signals speed up. This leads the brain to release adrenaline, which can speed up the heart and increase blood pressure. Because of its effect on adenosine receptors, caffeine can trigger supraventricular arrhythmias. On the other hand, a study published in the Nov. 7, 1990, issue of "The Journal of the American Medical Association" failed to establish a connection between coffee and ventricular arrhythmias.
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