Right ventricular electrical and mechanical synchronization by properly timed septal pacing in a patient with right bundle branch block and first degree AV block--a case report.

We present a case of near-normalization of the QRS by septal pacing in a patient with dual-chamber pacemaker and underlying complete right bundle branch block and first degree atrioventricular block. The right ventricular mechanical synchronization suggested by the ECG was validated as such by strain echo. To the best of our knowledge, this is the first time it has been shown that the narrowing of the QRS corresponds to mechanical synchronization in a case of this seldom-recognized phenomenon.