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All about heart block first degree heart block second degree heart block third degree or complete heart block causes of heart block symptoms of heart block diagnosis of heart block treatments for heart block arrhythmias (abnormal heart rhythms) {bundle branch block cardiac arrhythmia atrial fibrillation atrial flutter supraventricular tachycardia sick sinus syndrome ventricular arrhythmias ventricular tachycardia ventricular fibrillation heart block Brugada syndrome long QT syndrome short QT syndrome Wolff-Parkinson-White syndrome (WPW syndrome)}

What causes heart block?

Heart block has a variety of causes. It can sometimes be a result of a congenital defect. It can also occur after a heart attack or as a result of myocarditis (inflammation of the heart muscle), cardiomyopathy (a disorder of the heart muscle) and other types of heart disease. Although these conditions are more common in older people, young people can also be affected. Heart block may also occur after heart surgery and in this case may be either temporary or permanent. Wenckebach block

may occur as a result of taking too much digoxin, or can occur after a heart attack. Heart block may be caused by coronary artery disease, inflammation of the heart muscle, rheumatic fever, or overdose of certain heart drugs. Treatment depends on the degree of heart block experienced. Some cases need no treatment while others require medication or an artificial pacemakers.

The electrical activity of the heart starts in the sinoatrial (SA) node in the atrium and travels through the atrioventricular (AV) node to reach the ventricles. The AV node is supplied by two different parts of the nervous system - the parasympathetic and sympathetic. These are both parts of the autonomic nervous system - which controls involuntary actions in the body. The sympathetic nervous system has nerves distributed to the heart, blood vessels, lungs, intestines and other organs in the abdomen. It governs functions in these areas by reflex action in balance with the parasympathetic nervous system, which supplies the same areas, but often provides the opposite function to the sympathetic nervous system. The AV node is sensitive to what is called autonomic tone - the action of the two branches of the autonomic nervous system together. Heart block may occur at any point along this electrical pathway. Heart block of the AV node can be of several types, and a doctor generally can diagnose these by looking at the patient's electrocardiogram (ECG, EKG).

There are two uncommon muscular degenerative diseases which are responsible for isolated heart block in adults - Lev's disease and Lenegre's disease. Hypertension (high blood pressure) and stenosis (tightening) of the aortic and mitral valves of the heart are specific disorders which will accelerate degeneration of the conducting system or cause the deposition of calcium or fibrosis of the system.

More information on heart block

What is heart block? - Heart block is a disorder of the heartbeat. Heart block is common in elderly people as their hearts have undergone degenerative changes.
What's first degree heart block? - First-degree heart block, or first-degree AV block, is when the electrical impulse moves through the AV node more slowly than normal.
What's second degree heart block? - Second degree heart block is a disease of the electrical conduction system of the heart. There are two distinct types of second degree heart block.
What's third degree or complete heart block? - Third degree heart block, also known as complete heart block, is a disease of the electrical system of the heart.
What causes heart block? - Heart block has a variety of causes. It can sometimes be a result of a congenital defect. It can also occur after a heart attack or as a result of myocarditis.
What are the symptoms of heart block? - The main symptom associated with heart block is fainting (syncope). Second degree heart block may not cause symptoms.
How is heart block diagnosed? - Heart blocks can be diagnosed with a test called an electrocardiogram (ECG), which measures the heart's electrical activity.
What're the treatments for heart block? - First-degree heart block requires no treatment even when it is caused by heart disease. A temporary pacemaker may be used in an emergency.
Heart & cardiovascular disorders Mainpage

Topics in heart disease and cardiovascular disorders

Coronary circulation disorders
Myocardium disorders
Heart valve disorders
Arrhythmias (abnormal heart rhythms)
Heart inflammation and infection
Congenital heart disease
Valvular disease (blood vessels disorders)
Procedures done for coronary artery disease
Devices used in cardiology
Diagnostic tests and procedures for heart diseases
Heart transplant

Featured articles on heart disease and cardiovascular disorders

Coronary artery disease
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Cardiac arrhythmia
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Aortic aneurysm
Atrial fibrillation

All information is intended for reference only. Please consult your physician for accurate medical advices and treatment. Copyright 2005,, all rights reserved. Last update: July 18, 2005