Arrhythmia And Conduction Disorders: What Is Heart Block And How Does It Affect Heart Rhythm?

Arrhythmia, or an abnormal heart rate, can occur because of a variety of different heart issues. Most often, it has something to do with the heart’s electrical system. However, the heart’s electrical system is complex and has several different parts. To put it simply, the electrical signals first start in your sinoatrial node, or your heart’s "natural pacemaker". They travel down something called the AV node, which can protect the lower part of your heart if too many signals are being sent erroneously. They then go through what are called the bundle branches, resulting in the bottom of your heart contracting. Usually, this allows both the top of the heart and the bottom to contract in sync, producing your heartbeat.

How does this result in conduction disorders?

Conduction disorders result when there is some interference in the electrical signal that passes through your heart. This can be a problem with the generation of electrical signals or with their reception. Electrical signals can also pass through your heart abnormally, or something may slow the signals passing through your heart down.

If a doctor finds you have a conduction disorder, they’ll first assess its severity and then prescribe treatment. This can involve medicines, a pacemaker, or surgery, depending on its severity. Conduction disorders generally fall under arrhythmia, as an irregular heartbeat is usually the first sign of a conduction disorder.

What is heart block? Is it also a type of conduction disorder?

Heart block is a type of arrhythmia and conduction disorder that strikes when electrical signals cannot properly reach the bottom of the heart or move through the heart slowly. The electrical signals need to reach the bottom of the heart so that the heart beats appropriately, so, heart block can slow down the heart's beats or cause it to skip beats. Despite the name sounding severe, as if the heart is being stopped, it does not always result in severe symptoms and sometimes requires no treatment.

As with many arrhythmias, heart block can be caused by a variety of different things. Certain medicines — like beta blockers — can cause heart block as a side effect. A heart attack and certain heart diseases can also damage the heart's electrical system. In addition, heart surgery or infections such as Lyme disease cause heart block as well. It’s possible to be born with heart block, too.

First-degree heart block

In first-degree heart block, the heart’s electrical system has only minor issues slowing it down, but otherwise, the electrical signals reach the bottom of the heart. Regular checkups with your doctor are important, as well as checking your pulse in case it becomes worse. First-agree heart block is not, however, usually not something to worry about. First-degree heart block rarely presents with any symptoms. Because of this, no treatment beyond what was recommended above is necessary.

Second-degree heart block

Unlike third-degree heart block, second-degree heart block is not fatal. However, it can still lead to severe and potentially hazardous symptoms. In second-degree heart block, the signal may be slowed like in first-degree heart block, but unlike first degree-heart block it progressively gets slower and slower until the heart misses a beat trying to catch up.

Second-degree heart block can also present with the heart’s electrical system unsystematically failing to send a signal. This doesn’t stop your heart, but it can cause it to miss a beat. Second-degree heart block can present with symptoms like a slow heart, feeling like you skipped a beat, dizziness and faintness, chest pain, and tiredness.

For treatment, a doctor may recommend a pacemaker. A pacemaker can give off electrical signals that allow your heart to mimic the normal electrical system that your heart should have. Because medicine and injuries can also cause heart block, changing your medications or the recovering over time can cause the heart block to stop. However, do not stop taking medicines unless your doctor tells you to, as that can cause other problems or make your current condition worse.

Third-degree heart-block

Luckily, the bottom of the heart can generate its own electrical signals to keep itself beating, but it beats more slowly, and independently of the normal heart rate. This causes the heart to be far less effective at pumping blood through the body, which leads to more severe presentations of the symptoms of second degree heart block, and can also cause fainting. This can result from worsening second-degree heart block, and those with third-degree heart block receive immediate medical attention. Devices can be used to temporarily restore the heart’s regular beats before a pacemaker is implanted.