Absence of particle-induced coronary vasoconstriction during cardioplegic infusion: is it desirable to use a microfilter in the infusion line?
Many cardiac surgical units now use a microfilter in the infusion line for delivery of crystalloid cardioplegic solution to protect against the potential hazards of particulate contamination of cardioplegic solution. The aim of this group of studies was to determine the effects of particulate contamination of cardioplegic solutions, in order to establish whether a microfilter is needed in the infusion line. Total particle counts performed on two commercial cardioplegic solutions were low, but there were sufficient particles greater than 10 microns in diameter to cause coronary vasoconstriction. In isolated rat hearts a 20-minute infusion of St. Thomas' Hospital cardioplegic solution produced a progressive reduction in coronary flow, which was not prevented by the inclusion of a 0.8 micron filter in the infusion line. Two studies were performed on canine hearts to determine the effects of unfiltered cardioplegic solution on coronary vascular resistance. In the first, cardioplegic solution at 20 degrees C was infused for 20 minutes at a constant pressure of 50 mm Hg and flow rate was measured. In the second, the same solution at 4 degrees C was infused at a constant flow rate for 2 1/2 minutes and the infusion pressure was measured. In neither study did coronary vascular resistance rise. A final clinical study involving patients undergoing coronary bypass surgery compared the effects on coronary resistance of infusion at a constant flow of filtered versus unfiltered cardioplegic solution (n = 10 in each group). There was a similar rise in coronary perfusion pressure in both groups during the infusion. We conclude that there is insufficient evidence of particle-induced coronary vasoconstriction to justify the expense of a microfilter in the cardioplegic infusion line.
Munsch
C
C
Baker Medical Research Institute, Melbourne, Australia.
Rosenfeldt
F
F
Chang
V
V
Newman
M
M
Davis
B
B
D000818:Animals; D001639:Bicarbonates; D002122:Calcium Chloride; D002314:Cardioplegic Solutions; D003331:Coronary Vessels / Q000502:physiology*; D004285:Dogs; D004340:Drug Contamination; D005374:Filtration / Q000295:instrumentation*; D006324:Heart Arrest, Induced / Q000295:instrumentation*; D006801:Humans; D008274:Magnesium; D008297:Male; D010316:Particle Size; D011189:Potassium Chloride; D051381:Rats; D012965:Sodium Chloride; D014661:Vasoconstriction / Q000502:physiology*
D001639:Bicarbonates; D002314:Cardioplegic Solutions; C041711:St. Thomas' Hospital cardioplegic solution; D012965:Sodium Chloride; D011189:Potassium Chloride; D008274:Magnesium; D002122:Calcium Chloride