What Is Heart Block?
A healthy human heart typically beats between 60 and 100 times per minute. Each heartbeat results from the contraction of the heart muscle, which pushes blood throughout the body. These contractions are usually regulated by electrical signals that travel from the atria to the ventricles or from the upper chambers to the lower chambers of the heart. A partial heart block occurs when these electrical impulses are delayed or interrupted, causing irregular heartbeats. A complete heart block happens when the electrical signals are completely blocked, leading to a heartbeat that may drop to about 40 beats per minute. Heart blocks can vary in severity, with some causing only brief interruptions in the heart’s rhythm, while others can impede blood circulation, making it difficult for muscles and organs, including the brain, to receive adequate oxygen. Depending on the severity, heart block can be dangerous, with third-degree heart blocks potentially exacerbating pre-existing conditions like heart failure, causing loss of consciousness, or even sudden cardiac arrest. Chest pain can also occur. In contrast, coronary heart disease arises when waxy substances build up in the coronary arteries, potentially leading to chest pain, angina, or a heart attack, also known as myocardial infarction.
Symptoms of heart block may include:
– Slow or irregular heartbeats, or palpitations
– Shortness of breath
– Lightheadedness or fainting
– Chest pain or discomfort
– Difficulty exercising due to inadequate blood circulation
People with heart block might seem healthy but could have underlying heart issues.
The causes of heart block involve disruptions in the electrical impulses that guide heart muscle contractions. These impulses travel through the atrioventricular (AV) node along a pathway that includes the cardiac fibers known as “bundle branch blocks” or the “AV bundle.” This bundle splits into the right and left branches, which conduct impulses to the heart’s ventricles. Damage to one of these branches can result in irregular ventricular contractions and abnormal heart rhythms. Right-sided blocks are generally less severe, while left-sided blocks may indicate a higher risk of coronary artery disease or other heart problems.
Treatment for heart block varies based on the underlying cause. Many individuals with bundle branch block do not exhibit symptoms and may not require specific treatment. However, addressing any underlying issues, such as high blood pressure, is important. For individuals with left bundle branch block who experience a heart attack, reperfusion therapy may be used to restore blood flow to blocked arteries. This often involves anti-clotting agents like streptokinase to dissolve blood clots, though these medications carry a risk of bleeding. An artificial pacemaker, a small device implanted under the skin near the collarbone, may be used for patients with a history of syncope. This device, implanted during a 1 to 2-hour surgical procedure under local anesthesia, helps regulate the heart’s rhythm by generating electrical impulses when needed. Pacemakers generally have long-lasting batteries and are not affected by cell phones, personal stereos, or home devices, though individuals with pacemakers should avoid MRI scans.