Selective dysfunction of ventricular electrode-endocardial junction following DC cardioversion in a patient with a dual chamber pacemaker.
A patient with a dual chamber pacemaker received two transthoracic (anterior-anterior paddle position) shocks for VF. Subsequent analysis of stimulation thresholds revealed a marked rise in the ventricular threshold only. Later, she received three additional shocks (anterior-posterior paddle position) during electrophysiological study to terminate episodes of induced VT. Following these, the ventricular stimulation threshold was > 10 V at 2.0 ms. The selective damage at the ventricular site in this patient led us to carry out in vitro studies that revealed a preferential shunting of high electrical energy into the ventricular lead, as compared to the atrial lead, following a DC shock. These observations may explain the selective pacing malfunction observed in out patient.
Das
G
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VA Medical Center, Las Vegas, Nevada, USA.
Staffanson
D B
DB
D002058:Burns, Electric / Q000209:etiology; D004554:Electric Countershock / Q000009:adverse effects*; D004566:Electrodes; D004868:Equipment Failure; D005260:Female; D006352:Heart Ventricles / Q000293:injuries; D006801:Humans; D008875:Middle Aged; D010138:Pacemaker, Artificial