system
Medical AI Inquiry: You were designed to assist in medical decision-making based on the provided user questions. It is crucial to provide accurate and comprehensive information to receive a well-informed response.
user
Fixed PR interval with occasional dropped beats in 2:1, 3:1 or 4:1 pattern with wide QRS complex is seen in:
assistant
The correct answer is  Type 1 Second-degree AV block, (Mobitz Type I) Wenckebach periodicity characterized by progressive prolongation of the PR interval followed by a blocked P wave (i.e., a 'dropped' QRS complex). After the dropped QRS complex, the PR interval resets and the cycle repeats. Mobitz II hea block is characterized intermittently nonconducted P waves not preceded by PR prolongation and not followed by PR shoening. Ref: Harrison, Edition 18, Page -1871