Contrary to what the name implies, heart block is not a condition in which the blood vessels or coronary arteries are blocked. Rather, heart block occurs when the impulses originating from the sinoatrial node (also called the SA node, this is the heart’s natural pacemaker located in the right atrium) that cause the heart to beat don’t properly reach the lower chambers of the heart, or the ventricles. This is because the path the impulses travel along, called the AV node, is blocked.
There are three different levels of heart block, each with varying degrees of seriousness.
First-Degree Heart Block
With first-degree heart block, the patient usually has a healthy heart with normal beating patterns and will not need treatment. In a normally functioning heart, the electrical impulse travels from the atria to the ventricles along the AV node in about .2 seconds. With first-degree heart block, however, it takes longer.
Second-Degree Heart Block
Second-degree heart block is more serious than first-degree heart block and occurs when entire signal from the top chambers don’t reach the lower chambers. This can result in a feeling of skipped heartbeats. In some cases, second-degree heart block may cause bradycardia, or an abnormally slow heartbeat. When this is the case, the doctor may opt to install a pacemaker.
Third-Degree Heart Block
This is the most serious form of heart block. Also called complete heart block, third-degree heart block occurs when the impulses don’t reach the ventricles, causing the pacemaker in the ventricles to take the place of the SA node. The ventricle’s pacemaker is not as effective as the one located in the atria, and as a result the heart pumps blood at a much slower rate. People with third-degree heart block will require a pacemaker to keep the heart beating at a normal rate.
What Causes Heart Block?
There are a number of different causes for heart block. It tends to occur more frequently in older people in addition to those who have the following:
? Previous heart attack.
? Existing heart conditions. Coronary artery disease.
? Sick sinus infection
? Congenital heart defects.
What are the Symptoms?
The most common symptoms of heart block include:
? Bradycardia, or abnormally slow heart beat.
? Shortness of breath. A person with heart block may experience shortness of breath even when not doing anything exerting.
? Arrhythmias. These can include tachycardia (abnormally fast heartbeat) as well as an irregular heartbeat.
Some of the more severe symptoms include:
? Fainting spells
? Dizziness
? Extreme fatigue
? Heart failure (in rare cases)
How Is It Treated?
Heart block does not always require treatment. The treatment, if any, depends on the degree of the heart block. First degree heart block generally requires no treatment. With second degree heart block, the doctor may put the patient on medication to correct the arrhythmia that comes as a result of heart block. Anti-arrhythmic drugs will help slow trachycardia and restore the heart to a normal rhythm. In some cases, a pacemaker may be installed for second-degree heart block if symptoms of bradycardia are severe enough.
Third degree heart block almost always requires the use of a permanent pacemaker. In addition, an external pacemaker may be required to shock the heart to normal rhythm if the patient goes into cardiac arrest at the hospital as a result of heart block.