Second Degree Heart Block: Causes, Symptoms, Diagnosis & Treatment

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Some patients have an acquired heart block, meaning that they developed it at a point in their life, while others have a congenital heart block, meaning that they were born with it. A second degree heart block is characterized by a significant slowing of the electrical signals between the atria and ventricles. This results in blood not being pumped to the rest of the body due to not contracting when there is a blockage of the electrical signal before it reaches the ventricles. This degree of heart block has two types known as Mobitz type I and Mobitz type II.


If the cause is congenital, it may occur due to the babies mother having lupus or another autoimmune disease. Certain congenital heart defects may also cause this condition.

If the heart block is acquired the most common cause is heart attack-associated damage. Other causes may include coronary heart disease, heart failure, cardiomyopathy, myocarditis, and rheumatic fever. Other factors may increase a patient’s risk, such as certain types of surgery, sarcoidosis, Lev’s disease, Lenegre’s disease, overly active vagus nerve, certain genetic mutations, exposure to certain toxic substances, and certain medications, such as beta-blockers, digitalis, and calcium channel blockers.

Signs and Symptoms

The following may occur with a second degree heart block:

  • Fainting
  • Fatigue
  • Chest pain
  • Dizziness
  • Shortness of breath
  • Feeling lightheaded

If any symptoms are severe or new, treat it as a medical emergency and seek medical attention immediately.


The doctor will begin by asking the patient to provide a personal and family medical history. Next, a physical exam is performed. During the exam, the doctor will be looking for heart murmurs, abnormal heart rhythms, signs of heart failure or an enlarged heart, rate of heart beat and pulse, and signs of other diseases that could be causing issues.

An electrocardiogram is often next. This test will show the heart’s rhythm and how fast it is beating. This will often be done in a hospital, but a portable event or Holter monitor may also be used.

Electrophysiology studies may also be conducted. For this test, the doctor will pass a flexible, thin wire through one of the patient’s groin veins or arm veins and to their heart. The heart’s electrical signals will be recorded by the wire.


This degree of heart block may require the patient to get a pacemaker. This is a device that signals the heart to beat at a rate that is normal through the use of electrical pulses. It is placed under the skin of the abdomen or chest. If an underlying condition is the cause, treating and controlling this condition is often beneficial. Medications, such as atropine, may also be beneficial.


National Heart Lung and Blood Institute. (2010). Types of Heart Block. Retrieved on December 22, 2010 from the National Heart Lung and Blood Institute:

American Heart Association. (2010). Heart Block. Retrieved on December 22, 2010 from the American Heart Association: