Mobitz type II block usually occurs in patients with bundle-branch block implying bilateral bundle-branch disease and a poor prognosis.1-4 The site of block in such cases is distal to the His bundle recording site.5 We have recently reported three patients with type II block with narrow QRS complex and a site of block proximal to the His bundle.6 The conduction defects in these patients were not progressive, suggesting that type II block proximal to the His bundle was a benign condition.
Simultaneously with the publication of this latter study, we have seen a patient with type II block proximal to the His bundle, a narrow QRS complex, and prolonged periods of asystole. This patient is the subject of the present report.
The patient was a 65-year-old man admitted to Cook County Hospital on Dec 3, 1971, with a history of syncope. While waiting in the