Types of Heart Block

Your heart beats and pumps blood because it receives signals from its electrical system, also known as the cardiac conduction system. The electrical impulses travel through a series of specialized cells, helping the heart to beat in a coordinated, organized way. If there is any problem with that conduction system, you may be diagnosed with a condition called heart block.

“Heart block is when one or more of those components starts to fail. The cardiac impulse may not be conducted from one part of the heart to the next part of the heart. Or sometimes the impulse happens, but it happens relatively slowly,” says Michael Mazzini, MD, a Mass General Brigham cardiac electrophysiologist and director of the Center for Heart Health at Wentworth-Douglass Hospital.

“Heart block also can cause skipped beats,” adds Dr. Mazzini. “That can create problems, most often with a slow heartbeat, which can result in fainting spells, dizziness, falls, and, rarely, cardiac arrest.” 

He emphasizes that accurate diagnosis by a cardiologist and electrophysiologist can help determine the type of heart block you have and whether you need treatment. For those who do, a pacemaker can help keep you safe, get you back to normal activities, and lengthen your life span.

Causes of heart block

Generally, the chances of developing heart block increase with age. A number of things can cause the condition:

• Cardiac conditions: Most cases of heart block are caused by common acquired heart conditions that weaken the heart over time. Examples include coronary artery disease, previous heart attack, and cardiac fibrosis (scarring of heart muscle).
• Congenital heart conditions: A baby can be born with problems with the heart’s conduction system. This often occurs with other congenital heart conditions.
• Genetic conditions: Heart block isn’t usually inherited from generation to generation in a family. However, some conditions associated with genetic mutations can lead to heart block. For example, sarcoidosis is an inflammatory disease that can affect several organs, including the heart.
• Infections: Certain infections can affect the heart, most notably Lyme disease.

Heart block symptoms

Some people with heart block have no signs or symptoms. The condition may simply show up on a test they were having for another reason. But a severe case of heart block can affect your heart’s ability to pump blood.

Most people with heart block experience: 

• Dizziness
• Fatigue
• Inability to increase their activity level when they want to
• Lightheadedness
• Slow heart rate, skipped heartbeats, or irregular heartbeats (called arrhythmia)

A variety of conditions may cause those symptoms, so Dr. Mazzini advises that people seek medical attention if they experience multiple, sudden fainting spells, especially if they cause injury. 

Diagnosing heart block

An important step in heart block diagnosis is a conversation with a cardiologist or cardiac electrophysiologist. They’ll thoroughly review your health history, symptoms, and maybe even data from your smartwatch. 

Your doctor also may order a 12-lead electrocardiogram (EKG). This test records and tracks the electrical activity of the heart from 12 angles. However, sometimes the 12-lead EKG is normal with people who have heart block symptoms. 

In this case, your doctor may need to monitor you for a longer period of time with a wearable monitor. You’ll wear a device outside your body for up to 30 days. The device detects and records episodes, providing important information to your health care team.

Some people require longer-term monitoring. “There are implantable monitors about the size of a matchstick that can go under the skin and monitor the heart rhythm for several months and up to several years,” says Dr. Mazzini. “That can be very helpful for doctors to diagnose some of the more elusive forms of heart block.” 

Types of heart block

There are different types of heart block, depending on where the problem in the heart’s conduction system occurs. A person can have more than one type of heart block at the same time, Dr. Mazzini notes.

Sinus node dysfunction 

This type of heart block (formerly called sick sinus syndrome) is a problem in the sinus node. The sinus node is a cluster of tissue that acts as the heart’s natural pacemaker, controlling the heartbeat. 

Treatment for heart block

Milder forms of heart block may not require treatment, but people with symptomatic heart block or third-degree heart block should get a pacemaker. A provider implants this small device in the heart to regulate irregular heart rhythm and rate associated with heart block. Some pacemakers also include a defibrillator, which can send a shock to the heart when needed to restore normal rhythm. After you recover from the implant procedure, you should be able to get back to your usual activities. 

“Our goal when we put in a pacemaker is to restore you to the person that you were before you needed the pacemaker. For some people, that can get them back to doing everything, such as exercise, sexual activity, and having a very active life,” Dr. Mazzini says.

Lifestyle changes to improve heart health 

Dr. Mazzini encourages patients with heart block to take excellent care of their heart health. Here’s what you can do:

• Control your blood pressure.
• Maintain healthy cholesterol levels.
• Manage other medical conditions, such as diabetes.
• Get regular exercise.
• Follow a heart-healthy diet.