User:Mr. Ibrahem/Second-degree atrioventricular block

Second-degree atrioventricular block (second-degree AV block) is were the electrical signals from the upper to lower chambers of the heart are occasionally blocked. It is divided into Mobitz type I and Mobitz type II. Type I disease usually has no symptoms while type II disease often presents with tiredness, shortness of breath, chest pain, or syncope. Type II disease may progress to third-degree AV block or sudden cardiac death.

Type I may be normal in a younger person or athlete. However, it may also occur due to coronary artery disease, certain medications, high blood potassium, cardiomyopathy, rheumatic fever, or after heart surgery. Medications that may be involved include beta blockers, calcium channel blockers, antiarrhythmics, and digoxin. Type II disease is generally always due to an underlying problem.

Diagnosis is by electrocardiogram (ECG). In type I disease the PR interval becomes longer with each beat, until an atrial impulse is completely blocked resulting in a dropped beat. In type II the PR interval dose not change and atrial impulses are intermittently blocked. If every second beat is dropped it can be difficult to differentiate between type I and II. It is a type of atrioventricular block.

Specific teatment for type I disease is often not necessary. Medication that may be worsening the condition may be reduced or stopped and the person follow up. If a slow heartrate or low blood pressure occurs this can often be treated with atropine. Rarely cardiac pacing maybe required. Type II disease is nearly always treated with cardiac pacing. Type I disease was first described by Karel Frederik Wenckebach in 1899, while type II disease was first described by Woldemar Mobitz in 1924.