The Subtle Pattern of Sinoatrial Wenckebach

Area of Science:

• Cardiology
• Electrophysiology
• Internal Medicine

Background:

• Second-degree sinoatrial (SA) exit block type I, also known as SA Wenckebach, is an uncommon arrhythmia.
• It is characterized by a specific pattern of P-P intervals and dropped P waves on an electrocardiogram (ECG).
• This condition can present with a grouped beating pattern.

Purpose of the Study:

• To report a case of second-degree SA exit block type I.
• To highlight the diagnostic and management considerations for this rare arrhythmia.
• To emphasize the importance of recognizing SA exit block to differentiate it from other cardiac conditions.

Main Methods:

• A case presentation of a 64-year-old male with multiple comorbidities and bradycardia following a mechanical fall.
• Electrocardiogram (ECG) was used to diagnose a new SA exit block type I.
• Echocardiography was performed to assess cardiac function, revealing preserved ejection fraction and grade II diastolic dysfunction.

Main Results:

• The patient presented with bradycardia and a new diagnosis of second-degree SA exit block type I on ECG.
• Echocardiography indicated preserved ejection fraction and grade II diastolic dysfunction.
• Discontinuation of nodal blockers led to resolution of the arrhythmia.

Conclusions:

• Second-degree SA exit block type I can be managed conservatively by discontinuing offending medications.
• Pacemaker implantation was not necessary in this case.
• Accurate ECG interpretation is crucial to distinguish SA exit block from atrioventricular block or sinus arrhythmia.