Overview Of Heart Block: Abnormalities Of The Electrical System

The rhythm of your heartbeat is determined by the electrical impulses generated by your sinoatrial node. These impulses start in the two upper chambers (i.e. atria) and work downward through the two lower chambers (i.e. ventricles). As they travel downward, they cause contractions in your atria and ventricles. These contractions allow your heart to pump blood. Each electrical impulse measures a single heartbeat.

Heart block (HB) is a condition in which something disturbs the normal path of the impulses. The disorder can be congenital or acquired. The latter case is more common and can be caused by rheumatic fever, coronary artery disease, myocardial infarction, and certain types of medications.

Below, we’ll explore the three degrees of heart block. We’ll describe the symptoms associated with each and explain how the disorder is treated.

First-Degree

First-degree HB describes a slowing of the electrical signals as they travel from the atria to the ventricles. It is more prevalent among those whose vagus nerve is extremely active (e.g. athletes); such activity tends to slow the heartbeat. Medications such as digoxin, which are often prescribed to strengthen the heart’s contractions, can also cause first-degree HB. Treatment is unnecessary because symptoms rarely manifest.

Second-Degree

Similar to first-degree heart block, second-degree HB is marked by a slowing of the sinoatrial node’s electrical signals as they move from the atria to the ventricles. However, they slow dramatically; some of the signals fail to reach the ventricles.

Second degree HB is typically categorized into Mobitz Type I and II. In Type I, the electrical impulses slow increasingly with each beat until the heart eventually skips a beat. As a result, you might feel a slight dizziness. In Type II, there is far less regularity in the rhythm of the heartbeats. Symptoms are usually more serious.

Third-Degree

With third-degree HB, each of the signals produced by the sinoatrial node fail to reach the ventricles. As a result, contractions in the ventricles may be triggered by signals generated within the chambers themselves. Unfortunately, these self-generated signals lack coordination with the contractions of the atria, eventually leading to cardiac arrest and death.

Treatment For Heart Block

Because first-degree HB is a relatively minor condition and presents few symptoms, there is rarely a need for treatment. Patients can live fulfilling lives with no complications or health issues related to the disorder.

Second-degree HB may require the installation of a pacemaker, especially in the case of Mobitz Type II. The pacemaker is implanted underneath your skin and helps to control an abnormal heartbeat.

If you suffer from third-degree heart block, you will need to have a pacemaker implanted. Because the impulses from the sinoatrial node fail to reach your ventricles, the pacemaker will produce artificial signals and send them to the atrioventricular node. In effect, the device completes the connection that HB is disrupting.

Heart block is usually only serious if the connection between the sinoatrial node and atrioventricular node is severed. In such cases, a pacemaker will typically resolve the problem.

Related posts:

  1. Understanding How A Pacemaker Works To Prompt A Heartbeat
  2. What Is The Maze Procedure?
  3. An Exploration Of Different Types Of Heart Surgeries
  4. How A Pacemaker Can Keep A Heart Running Smoothly
  5. Surgical Techniques Used During An Atrial Maze Procedure