In this defect, the heart's electrical signal doesn't pass from the heart's own natural pacemaker in the atrium to the lower chambers. When this occurs, an independent pacemaker in the lower chambers takes over. The ventricles can contract and pump blood, but at a slower rate than the atrial pacemaker. Complete heart block is most often caused in adults by heart disease or as a side effect of drug toxicity. Heart block also can be present at birth. This is called congenital heart block. It also may result from an injury to the electrical conduction system during heart surgery. When the pacemaker in the ventricles isn't fast enough or reliable enough, an artificial pacemaker is put in. Heart block can be of varying degrees:
First-degree heart block, or first-degree AV block, is when the electrical impulse moves through the AV node more slowly than normal. The time it takes for the impulse to get from the atria to the ventricles should be less than about 0.2 seconds. If it takes longer than this, it's called first-degree heart block. Heart rate and rhythm are normal, and there may be nothing wrong with the heart. Certain heart medicines such as digitalis can slow conduction of the impulse from the atria to the ventricles and cause first-degree AV block.
In second-degree heart block, some signals from the atria don't reach the ventricles. This causes "dropped beats."
In third-degree or complete heart block, no signal passes from the atria to the ventricles. This requires a pacemaker.
Congenital heart block, when detected at or before birth in a structurally normal heart, is strongly associated with autoantibodies reactive with certain proteins
First-degree heart block, or first-degree AV block, is when the electrical impulse moves through the AV node more slowly than normal. The time it takes for the impulse to get from the atria to the ventricles should be less than about 0.2 seconds. If it takes longer than this, it's called first-degree heart block. Heart rate and rhythm are normal, and there may be nothing wrong with the heart. Certain heart medicines such as digitalis can slow conduction of the impulse from the atria to the ventricles and cause first-degree AV block.
In second-degree heart block, some signals from the atria don't reach the ventricles. This causes "dropped beats."
In third-degree or complete heart block, no signal passes from the atria to the ventricles. This requires a pacemaker.
Congenital heart block, when detected at or before birth in a structurally normal heart, is strongly associated with autoantibodies reactive with certain proteins