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Causes of a Second-Degree Heart Block

The human heart has two chambers: the atria (upper chamber) and the ventricle (lower chamber). Electrical impulses are sent from the atria to the ventricle, and when those impulses are not sent on a steady, regular basis, a condition develops which is known as second-degree heart block, or atrioventricular block. There are two types of block, known as Mobitz I and II. There are several causes for each type of heart block.

  1. Heart Attack

    • Both types of second-degree heart block can occur after a heart attack. In the first type, Mobitz I, the signals from the upper chamber to the lower chamber progressively increase in time and then stop. According to MDGuidelines, this condition is not fatal, and normally following a heart attack will resolve itself without treatment. In Mobitz II, there is an unexpected impulse. Once this problem is identified, it will not resolve itself, can be fatal, and generally requires a pacemaker to correct.

    Drug Use

    • Heart block can be caused by drug use, according to the National Heart Lung and Blood Institute. The type of drugs that place a person in jeopardy of the heart block are beta blockers, calcium channel blockers and digitalis, all of which are medications specifically designed for the heart. Mobitz II is more likely to develop as a result of the use of these drugs.

    Disease

    • Certain diseases have been linked to second-degree heart block, including Lyme disease which is spread by tick bites, according to eMedicine. Other diseases that cause the blockage are cardiomyopathy, or heart muscle disease, and Lev's and Lenegre's disease, both of which are diseases that attack the heart.

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