The pattern 'Longer, longer, drop' describes which second-degree block type?

The pattern 'Longer, longer, drop' describes which second-degree block type?

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

Answer: (A)

Longer, longer, drop is the classic description of Mobitz type I, a second-degree AV block also called Wenckebach. In this pattern the PR interval keeps getting longer from one beat to the next until a P wave is not followed by a QRS complex—a dropped beat. After that, the cycle starts again with a shorter PR interval. This reflects progressively delaying conduction through the AV node, and it can occur with conditions or drugs that slow AV nodal conduction. Why this fits best: the defining feature is the gradual PR prolongation culminating in a dropped beat, which sets Mobitz type I apart from the other patterns. For contrast, Mobitz type II shows occasional dropped QRS without PR lengthening; first-degree block has a consistently prolonged PR with every P conducted; and third-degree block has complete AV dissociation with no fixed relationship between P waves and QRS.

Longer, longer, drop is the classic description of Mobitz type I, a second-degree AV block also called Wenckebach. In this pattern the PR interval keeps getting longer from one beat to the next until a P wave is not followed by a QRS complex—a dropped beat. After that, the cycle starts again with a shorter PR interval. This reflects progressively delaying conduction through the AV node, and it can occur with conditions or drugs that slow AV nodal conduction.

Why this fits best: the defining feature is the gradual PR prolongation culminating in a dropped beat, which sets Mobitz type I apart from the other patterns. For contrast, Mobitz type II shows occasional dropped QRS without PR lengthening; first-degree block has a consistently prolonged PR with every P conducted; and third-degree block has complete AV dissociation with no fixed relationship between P waves and QRS.