The Annals of Thoracic Surgery, Vol 47, 872-876, Copyright © 1989 by The Society of Thoracic Surgeons
Mitral valve function after cryoablation of the posterior papillary muscle in the dog
GM Guiraudon, CM Guiraudon, DG McLellan and JL MacDonald
Department of Surgery, University of Western Ontario, London, Canada.
Extensive cryoablation of an arrhythmogenic left ventricular posterior
papillary muscle associated with ventricular arrhythmias may affect mitral
valve function. We studied the long-term effects of extensive cryoablation
of the posterior papillary muscle and its ventricular attachment in 10
dogs. The dogs had hemodynamic, electrophysiological, and angiographic
testing 1 month after operation. Seven dogs were then killed, and the
hearts were examined at that time. Three dogs had repeat assessments 2 and
3 months after operation before they were killed. At 1 month, left
ventricular angiography showed normal mitral valve function in all dogs.
Pathological examination revealed that the posterior papillary muscle and
its left ventricular attachment were replaced by a discrete dense, fibrous
scar. The fibrous process involved the mitral valve in 2 dogs. At 3 months,
pathological examination showed a marked fibrous scar with chondroid
metaplasia and fibrous involvement of the mitral valve chordae and
posterior leaflet in all 3 dogs. We conclude that extensive cryoablation of
the posterior papillary muscle is not associated with long-term mitral
valve dysfunction, and may be the best surgical technique to ablate an
arrhythmogenic papillary muscle.
