Complete heart block is failure of the system of electrical impulses from the atrium to the ventricle. In this condition, the damage of the heart transmission tissue inables the the electrical impulses from the atrium to get to the ventricle, thus the ventricles can not properly function. The heart muscle contracts automatically although there is a lack of a signal. The ventricles contract 40 times per minute, or less, instead of the normal 60-80 beats per minute, which significantly reduces the efficiency of the heart. In certain cases, the heart can completely stop beating, even up to 20 seconds.
There are four degrees of heart block:
- first-degree – slowed down electrical impulses, but they get to the ventricles
- second-degree (type I) – the electrical impulses are increasingly delayed until a beat fails to reach the ventricle
- second-degree (type II) – some of the electrical impulses do not get to the ventricles; rare than type I, but more serious
- third-degree (type III) or complete heart block – none of the impulses get to the ventricles
- bundle branch block – the electrical impulses are slowed or blocked on the way to the conducting tissue.
Complete heart block occurs more frequently in older people.
The symptoms of complete heart block occur gradually or suddenly. These are:
- palpitations (discomforting feeling of irregular, abnormal heart beats or pounding)
- loss of consciousness when the heart stops beating
- lack of breathing air
- chest pain
The causes of complete heart block are often coronary artery diseases, since one or more arteries supplying the heart with oxygen-rich blood may be narrowed. Myocardial infarction can also be a cause for subsequent complete heart block. Then, heart valve problems, medications, exposure to toxic substances, Lyme disease and aging are other possible causes.
The risk factors for complete heart block are:
- coronary artery disease
- heart attack
- fat-rich diet
- lack of physical activity
- congenital heart disease
The complications of complete heart block can arise of left untreated. These are: acute or chronic heart failure, shock, stroke, even death.