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Cardioplegia: Prevention of inadequate preservation
J Mol Cell Cardiol 22 (Supplement V) (1990)
K4 CARDIOPLEGIA:
PREVENTION
OF INADEQUATE
PRESERVATION
Gerald
D. Buckberg, UCLA School of Medicine, Los Angeles, Calif. 90024 Cold antegrade cardioplegia is used almost universally to provide a quiet bloodless field during cardiac operations and to "prevent" damage during aortic clamping. This report is intended to emphasize the critical importance of using blood as the vehicle for cardioplegic delivery to expand the versatility of cardioplegia, and to introduce the concept of combining antegrade and retrograde techniques to ensure optimal cardioplegic delivery. It will describe also how warm blood cardioplegic solutions can be used for "active resuscitation" before ischemia is imposed, and to "avoid" and "reverse" ischemic and aortic unclamping. reperfusion damage before and after
EUROPEAN ORIGINS OF CARDIOPLEGIA Hospital, London SE1 7EH, England.
by
M.V.
Braimbridge,
Rayne Institue,
St.
Thomas'
Cardioplegic myocardial protection began serendipitously with the bolus technique of Melrose and Bantall in 1955 but was subsequently clinically abandoned due to myocardial damage attributed to normothermia and the high concentration of potassium citrate. The principle however was kept alive in Eurpoe by HBlschar and Bretschneider in Germany and was again used clinically in the 1960s by Sondergaard in Denmark - the large volume "intracellular" low Na+ and Ca++ Bretschneider Solution - and Rodewald in Hamburg - the bolus Mg-aspartate Kirsch Solution. Hearse in London evaluated each component of the German solutions with dose response curves and promulgated "extracellular" St. Thomas' Solution with normal Na+ and Ca++ but high K+ and Mg++. This was introduced clinically in 1975. Subsequent European contributions have been in the techniques of administration of cardioplegia-retrograde coronary sinus perfusion in Paris ; evaluation of non-coronary collateral flow in Hannover; and emphasis on the special problems of infancy and childhood in London.
K6 THE FUTURE OF CARDIOPLEGIA: Andrew S. Wechsler,
M.D.
The current practice of cardioplegia fulfills many of the prophecies made five years ago. Minimally appreciated was the extent to which a changing population would interact with methods designed for myocardial protection. Cardioplegia is mandatory for safe heart operations. The challenge is to safely techniques", sensibly to meet a changing patient population. apply "cardioplegic Intervention in patients occurs during pre-ischemic intervals, during periods of ischemia and during periods of reperfusion. As the patient population shifts more toward those having ongoing ischemia or ischemia and reperfusion, the future will emphasize cardioplegia as a "resuscitative solution" more than as a metabolic inhibitory solution. Warm induction and terminal warm cardioplegic infusion are concepts that can be applied throughout the course of the cardioplagic interval. Components of cardioplagia still to be improved within this new construct include more effective scavenging of free oxygen radicals generated during reperfusion. The future will see the use of free radical traps that gain rapid access to the cell interior and perivascular spaces. Reperfusion edema remains a problem, particularly when reperfusion occurs following myocardial injury. Current osmotically active agents are inadequate because of their small size and capacity for gaining access to the interstitial space. New osmotically active agents with the potential to coat the endothelium are needed. Cardioplegic arrest is currently performed by depolarization with significant accompanying abnormalities inelectrolyte flux. Polarizing chemicals that specifically and selectively block sod,ium channels will become available such that "pixarized" arrest may be achieved. The influence of cell polarization on intracellular synthetic capabilites will need evaluation. Although glutamate and aspartata enrichment of the cardioplegic mixture has been beneficial, further refinements of metabolic supportwilloccur utilizing agents that are more interactive with high energy phosphate metabolitee or which can provide substrate for high energy phosphate generation. It is interesting that a generation of surgeons is emerging who have had no contact with the pre-cardioplegic era. Since some advances in the application of cardioplegic technology will require ingenuity more than chemistry, it will be important that surgical teachers rediscover fundamental cardiac physiology as new concepts evolve. S.37
K4 CARDIOPLEGIA:
PREVENTION
OF INADEQUATE
PRESERVATION
Gerald
D. Buckberg, UCLA School of Medicine, Los Angeles, Calif. 90024 Cold antegrade cardioplegia is used almost universally to provide a quiet bloodless field during cardiac operations and to "prevent" damage during aortic clamping. This report is intended to emphasize the critical importance of using blood as the vehicle for cardioplegic delivery to expand the versatility of cardioplegia, and to introduce the concept of combining antegrade and retrograde techniques to ensure optimal cardioplegic delivery. It will describe also how warm blood cardioplegic solutions can be used for "active resuscitation" before ischemia is imposed, and to "avoid" and "reverse" ischemic and aortic unclamping. reperfusion damage before and after
EUROPEAN ORIGINS OF CARDIOPLEGIA Hospital, London SE1 7EH, England.
by
M.V.
Braimbridge,
Rayne Institue,
St.
Thomas'
Cardioplegic myocardial protection began serendipitously with the bolus technique of Melrose and Bantall in 1955 but was subsequently clinically abandoned due to myocardial damage attributed to normothermia and the high concentration of potassium citrate. The principle however was kept alive in Eurpoe by HBlschar and Bretschneider in Germany and was again used clinically in the 1960s by Sondergaard in Denmark - the large volume "intracellular" low Na+ and Ca++ Bretschneider Solution - and Rodewald in Hamburg - the bolus Mg-aspartate Kirsch Solution. Hearse in London evaluated each component of the German solutions with dose response curves and promulgated "extracellular" St. Thomas' Solution with normal Na+ and Ca++ but high K+ and Mg++. This was introduced clinically in 1975. Subsequent European contributions have been in the techniques of administration of cardioplegia-retrograde coronary sinus perfusion in Paris ; evaluation of non-coronary collateral flow in Hannover; and emphasis on the special problems of infancy and childhood in London.
K6 THE FUTURE OF CARDIOPLEGIA: Andrew S. Wechsler,
M.D.
The current practice of cardioplegia fulfills many of the prophecies made five years ago. Minimally appreciated was the extent to which a changing population would interact with methods designed for myocardial protection. Cardioplegia is mandatory for safe heart operations. The challenge is to safely techniques", sensibly to meet a changing patient population. apply "cardioplegic Intervention in patients occurs during pre-ischemic intervals, during periods of ischemia and during periods of reperfusion. As the patient population shifts more toward those having ongoing ischemia or ischemia and reperfusion, the future will emphasize cardioplegia as a "resuscitative solution" more than as a metabolic inhibitory solution. Warm induction and terminal warm cardioplegic infusion are concepts that can be applied throughout the course of the cardioplagic interval. Components of cardioplagia still to be improved within this new construct include more effective scavenging of free oxygen radicals generated during reperfusion. The future will see the use of free radical traps that gain rapid access to the cell interior and perivascular spaces. Reperfusion edema remains a problem, particularly when reperfusion occurs following myocardial injury. Current osmotically active agents are inadequate because of their small size and capacity for gaining access to the interstitial space. New osmotically active agents with the potential to coat the endothelium are needed. Cardioplegic arrest is currently performed by depolarization with significant accompanying abnormalities inelectrolyte flux. Polarizing chemicals that specifically and selectively block sod,ium channels will become available such that "pixarized" arrest may be achieved. The influence of cell polarization on intracellular synthetic capabilites will need evaluation. Although glutamate and aspartata enrichment of the cardioplegic mixture has been beneficial, further refinements of metabolic supportwilloccur utilizing agents that are more interactive with high energy phosphate metabolitee or which can provide substrate for high energy phosphate generation. It is interesting that a generation of surgeons is emerging who have had no contact with the pre-cardioplegic era. Since some advances in the application of cardioplegic technology will require ingenuity more than chemistry, it will be important that surgical teachers rediscover fundamental cardiac physiology as new concepts evolve. S.37