The Annals of Thoracic Surgery, Vol 24, 566-573, Copyright © 1977 by The Society of Thoracic Surgeons
Is a left ventricular vent necessary during cardiopulmonary bypass?
KV Arom, JF Vinas, JE Fewel, VS Bishop, FL Grover and JK Trinkle
This study evaluated the coronary flow and the internal diameter, pressure,
and metabolism of the left ventricle using four different cardiopulmonary
bypass techniques. Conditioned dogs underwent a 30- minute stabilizing
period on cardiopulmonary bypass with a beating, empty heart (normothermia
and a flow of 80 ml/kg/min). They were then fibrillated and subjected to
four experiments: Group A (7 dogs)--left ventricular vent, caval tapes
open; group B (7 dogs)--left ventricular vent, caval tapes closed; group C
(7 dogs)--no vent, caval tapes open; group D (4 dogs)--no vent, caval tapes
closed. There was no major difference in any of these variables among
Groups A and B (both ventricles vented). Group D (no vent, tapes closed)
had significantly increased wall tension, decreased coronary flow,
decreased subendocardiac flow, and ischemia. In contrast, Group C dogs (no
vent, tapes open) had only a slight increase in left ventricular diameter
and pressure, with no change from Group A and B dogs in coronary flow,
lactate extraction, hydrogen ion production, or potassium difference.
Therefore, venting the fibrillating ventricle, either with or without
snaring of the caval tapes, is probably the best method to use during the
distal anastomosis in a coronary artery bypass operation. However, if a
vent is not used, the caval tapes should be left open to allow complete
diversion of the venous blood and decompression of the left ventricle.
