Which second-degree block type corresponds to Wenckebach pattern?

Which second-degree block type corresponds to Wenckebach pattern?

• A. 2nd Degree Type 1
• B. 2nd Degree Type 2
• C. 1st Degree
• D. 3rd Degree

Answer: (A)

Wenckebach is a second-degree AV block type I. The defining feature is a progressively lengthening PR interval with each beat until a P wave is not followed by a QRS, and then the cycle restarts. This pattern reflects transient delay at the AV node and is often vagally mediated or related to drugs affecting AV nodal conduction. It’s different from Mobitz II, where a QRS drop occurs without the preceding PR lengthening and the PR interval remains constant; from first-degree, where the PR interval is prolonged but every P is followed by a QRS; and from third-degree, where there’s complete AV dissociation with no consistent relationship between P waves and QRS complexes.

Wenckebach is a second-degree AV block type I. The defining feature is a progressively lengthening PR interval with each beat until a P wave is not followed by a QRS, and then the cycle restarts. This pattern reflects transient delay at the AV node and is often vagally mediated or related to drugs affecting AV nodal conduction. It’s different from Mobitz II, where a QRS drop occurs without the preceding PR lengthening and the PR interval remains constant; from first-degree, where the PR interval is prolonged but every P is followed by a QRS; and from third-degree, where there’s complete AV dissociation with no consistent relationship between P waves and QRS complexes.