The Annals of Thoracic Surgery, Vol 52, 903-907, Copyright © 1991 by The Society of Thoracic Surgeons
Effect of pH shifts induced by oxygenating crystalloid cardioplegic solutions
UO von Oppell, LM King, EF Du Toit, P Owen, B Reichart and LH Opie
Ischaemic Heart Disease Laboratory, University of Cape Town, South Africa.
Oxygenation of a bicarbonate-containing crystalloid cardioplegic solution
alters the partial pressure of both oxygen (O2) and carbon dioxide (CO2).
Therefore, oxygenating St. Thomas' Hospital II plus glucose (11 mmol/L)
cardioplegic solution with 95% O2 + 5% CO2 induces a pH shift to 7.0 (10
degrees C) as opposed to pH 9.3 with 100% O2. In an isolated working rat
heart model, we show that pH 7.0 (10 degrees C) improves mechanical
postischemic recovery in the absence or presence of O2. However, in the
absence of O2, pH 7.0 appears to inhibit glycolysis and diminish the
stability of cellular membranes. The provision of O2 independently improved
mechanical recovery and at pH 7.0, improved the preservation of the
sarcolemma. Increasing the O2 content by including a perfluorocarbon
(FC-43) in the oxygenated St. Thomas' plus glucose cardioplegia is not
additionally beneficial. St. Thomas' Hospital plus glucose cardioplegic
solution should be oxygenated, but with 95% O2 + 5% CO2 and not 100% O2.