Third-degree heart block – The primary concern with this condition is progression to a third-degree heart block. Of the two types of Second Degree Blocks, type I (Wenkebach) is considered LESS serious and LESS likely to progress to a third degree block.

Hemodynamic compromise (rare) – associated with bradycardia is effectively treated with atropine. If Atropine is ineffective, pacing may be required.

In general, second degree blocks are those where a P wave is present without a corresponding QRS complex.

Type I (wenkebach) is characterized by progressive prolongation between the P wave and the QRS complex until a QRS complex is completely dropped

This condition is suggestive of AV nodal disease is typically transient and benign/asymptomatic

This is thought to be caused by a progressive prolongation of the refractory period at the AV node after a normal depolarization of the heart. This continues until the impulse reaches the AV node at the absolute refractory period, and the QRS is completely dropped.

Etiology – Diseases that can cause this condition include myocardial infarction, ischemia, fibrosis or calcification. Any infiltrative or inflammatory process of the myocardium can also be the culprit. For this reason, cardiothoracic surgery may also trigger onset of this condition.

Pharmaceutical Etiology – Drugs that can cause this condition include calcium channel blockers, β-blockers, digoxin, and sympatholytic drugs