User:Mr. Ibrahem/Third-degree atrioventricular block

Third-degree atrioventricular block (third-degree AV block) is were the electrical signal from the upper chambers of the heart is unable to make it to the lower chambers. Symptoms may include tiredness, shortness of breath, chest pain, and syncope. Complications may include sudden cardiac death.

Causes may include ischemic heart disease, certain medications, electrolyte abnormalities, Lyme disease, lupus, and following heart surgery. Medications that may be involved include antiarrhythmics and digoxin. In some cases the cause is unclear. Diagnosis is by electrocardiogram (ECG), which typically shows a ventricular rate of less than 50 BPM and independent but faster atrial activity. The QRS complex can be narrow or wide. It is a type of atrioventricular block.

The heartrate may be raised with a dopamine or epinephrine infusion. This may be followed by transcutaneous or transvenous pacing and eventually a permanent pacemaker. While recommended, atropine is generally not effective. Third-degree AV block is rare, newly affecting about 3 in 10,000 people per year. The condition was first identified in an animal model in 1852 by Hermann Stannius.