This 82-year-old man is referred by his family physician because of the ECG abnormalities. He lives in a senior citizen apartment and is active and symptom-free with no history of dizziness or syncope:

• Sinus rhythm with type II sino-atrial exit block
• Junctional escape complex
• Right bundle branch block

Comment: In type II sino-atrial exit block the long PP cycle is often slightly shorter than a multiple of the average basic PP interval, because the sino-atrial conduction is faster after a long pause, the result of the longer period of recovery.