doi:10.1510/mmcts.2004.000729
Myocardial protection in congenital heart surgery Christian Schlensak* Department of Cardiovascular Surgery, University Hospital Freiburg, Hugstetter Strasse 55, 79106 Freiburg, Germany Modern pediatric cardiac surgery prides itself by performing primary surgical repair of cardiac anomalies. As a consequence, the majority of cases are nowadays performed in neonates and young infants. For the repair of intracardiac malformations the aorta is crossclamped and the heart is arrested (i.e. subjected to ischemia). Cardioplegic solution is administered routinely to arrest the contractile apparatus, decrease energy consumption and thereby increase ischemia tolerance. It is usually combined with hypothermia as another method to extend ischemia tolerance. In pediatric cardiac surgery several different cardioplegic solutions and strategies are currently used. For myocardial protection during crossclamp time either blood or crystalloid solution is administered into the aortic root or retrogradely into the coronary sinus, intermittently or as a single shot. The final concept for myocardial protection is highly dependent on the individual surgeon and his personal preference. There is currently no evidence in favor of one or the other technique. Thus, pediatric protection is currently experience-based.
Keywords: Blood cardioplegia; Myocardial protection; Pediatric cardiac surgery Introduction Although major advances in surgical techniques and technical aspects have been made in the field of congenital cardiac surgery, mortality remains high w1–3x. According to the EACTS congenital database w4x the 30-day mortality for all patients with congenital cardiac malformations is 5% (out of 24,637 patients in 2004) and exceeds 11% in neonates (out of 4,951 patients in 2004). Inappropriate myocardial protection during crossclamp time is still considered the main cause of death in the pediatric population w5x. It is interesting to note in this context, that the strategies for pediatric myocardial protection have remained relatively unchanged over the last decade. This is evident in the small number of publications available in the pediatric literature * Corresponding author: Tel.: q49-11-761-2702818; fax: q49-11761-2702368. E-mail: [email protected] 䉷 2005 European Association for Cardio-thoracic Surgery
compared to a large number on the same topic in adults. Adopting principles for myocardial protection established in adult patients for the pediatric patient population warrants caution because there are important structural and biochemical differences between the pediatric and adult myocardium. The main differences that relate to clinical practice are: 1. different pattern of substrate utilization 2. different activity levels of enzymes important for regeneration of ATP 3. the regulation of calcium metabolism. The pediatric heart utilizes mainly glucose as the oxidative substrate compared to fatty acids in the adult heart w6,7x. A shift towards glucose utilization is considered to improve ischemic tolerance w8x. A lower level of the enzyme 59nucleotidase as in the pediatric heart is associated with a higher end-ischemic level of AMP (that means preservation of the adenine 1
C. Schlensak / Multimedia Manual of Cardiothoracic Surgery / doi:10.1510/mmcts.2004.000729 cardioplegia was developed in Europe w19–21x) cardiac surgeons in North America use blood cardioplegia to protect the pediatric myocardium while most European centers are using crystalloid solution w22x. The principle difference between crystalloid and blood cardioplegia is that for blood cardioplegia the crystalloid solution is mixed with blood in a certain ratio (for example 1:4, crystalloid solution:autologous blood) while for crystalloid cardioplegia the solution is administered as is. Both, crystalloid and blood cardioplegia can be administered antegradely or retrogradely or as a single shot or intermittently. Photo 1. Set-up of the blood cardioplegic system of the heart-lung machine for pediatric myocardial protection. The roller pump (1) sucks blood from the oxygenator (2) and pumps it to the head exchanger (3). The line leading from the pump to the head exchanger has a Y-connector (4), which allows mixing of the blood with the crystalloid component of the cardioplegia (5). From the head exchanger the newly mixed blood cardioplegia is delivered to the patient (6). This cardioplegia delivery system is available from Sorin (MMCTSLink 76).
nucleotide pool), which is a prerequisite for recovery of function w9x. Finally, the calcium metabolism in the pediatric heart is immature. In the pediatric myocardium the sarcoplasmatic reticulum is underdeveloped and has reduced capacity for calcium storage w10x. In the pediatric heart the calcium is mainly provided by influx from the external space w10x. This difference makes it clear why the pediatric myocardium is so much more responsive to postischemic calcium overload. There are several reports describing the detrimental effects of cardioplegia solutions used for neonates containing normal or high calcium concentrations. Therefore most cardioplegia solutions used for the protection of the pediatric myocardium have lower than normal concentrations of calcium w2,11– 13x. Cardioplegic techniques Several techniques for myocardial protection in children have been proposed w1,2,14,15x. They differ in the cardioplegic solution used (crystalloid vs. blood), in the delivery root (antegrade vs. retrograde) and the frequency of its application (single shot vs. intermittent application). The final concept for myocardial protection is highly dependent on the individual surgeon and his personal preference. There is currently no evidence in favor of one or the other technique. Thus, pediatric protection is currently experience-based w16x. Most likely due to historical reasons (blood cardioplegia was developed in the US w17,18x and crystalloid 2
Surgical technique At our institution in Freiburg we use Buckberg’s cardioplegic solution w23x for myocardial protection in neonates and infants. The crystalloid solution is available (MMCTSLink 73). It is mixed through the delivery system of the heart-lung machine with autologous blood in a ratio 1:4 (crystalloid solution:autologous blood) prior to its application (Photo 1). If the aortic valve is competent the initial infusion is administered into the aortic root. After placement of a purse-string suture on the anterior part of the ascending aorta, the adventitia within the purse-string suture is incised with a No. 11 scalpel blade. Then the adventitia is gripped to both sides of the incision by a pair of forceps, after a No. 11 scalpel blade is advanced through the aortic wall within the pursestring suture. The hole can be closed by the adventitial flap. The cardioplegia cannula can then slide into the incision of the aortic wall and the purse-string suture can be snugged. After de-airing the cardioplegia line, the cannula is connected. The CPB is started and the ascending aorta is crossclamped and the myocardium arrested with cold blood cardioplegia (4 8C) (Photo 2). The initial infusion rate is 30 ml/kg body weight. Infusion pressure is not to exceed 80 mmHg for antegrade delivery. During aortic crossclamp time retrograde re-infusions are given every 20 min. Subsequent re-infusions are given retrogradely through a catheter which is placed into the coronary sinus. After placement of a purse-string suture around the ostium of the coronary sinus the catheter is connected to the cardioplegia line. Once the cannula is de-aired it is slowly advanced into the coronary sinus. The purse-string suture can be snugged and the cold cardioplegia re-infusion is delivered with 10 ml/kg body weight. This rate is several fold the volume used for cardioplegia of the adult heart, where infusion is
C. Schlensak / Multimedia Manual of Cardiothoracic Surgery / doi:10.1510/mmcts.2004.000729
Results Between January 1999 and June 2005 our strategy of myocardial protection was applied to 624 children presenting with the full spectrum of congenital cardiac malformations. Forty-two percent of our patients were less than 1 year of age. Mean aortic crossclamp time in all patients was 67"48 min (8–235 min). There were 6 hospital deaths (i.e. 1.0% overall mortality rate). None of them was related to inadequate myocardial protection. Our strategy of cardioplegia management did not increase the complexity of the procedure.
Discussion
Photo 2. Pediatric aortic root cannula and retrograde coronary sinus perfusion cannula with manual inflating cuff. The antegrade cardioplegia cannula (above) has a diameter of 4 French. The retrograde cannula (below) has a diameter of 6 French. Both cannulas are available from Medtronic DLP – MMCTSLink 74 and MMCTSLink 77).
Video 1. The right atrium is opened longitudinally in a standard manner. After placement of a purse-string suture around the ostium of the coronary sinus the catheter is connected to the cardioplegia line. Once the cannula is de-aired it is slowly advanced into the coronary sinus. The purse-string suture can be snugged and the cold cardioplegia re-infusion is delivered.
based on time rather than body weight. Infusion pressure is not to exceed 50 mmHg for retrograde delivery. The coronary sinus catheter will stay in place during the whole aortic crossclamp time (Video 1). This retrograde perfusion technique has the benefit, that the coronary arteries and the aortic root as well are sufficiently de-aired. If the aortic crossclamp time exceeds 60 min, a terminal warm substrate enriched infusion (‘hot shot’, 36 8C) is given through the coronary sinus catheter before the aorta is unclamped with a rate of 10 ml/kg body weight. During reperfusion the systemic reperfusion pressure is kept low (i.e. 30–40 mmHg) during the initial 5 min after blood flow to the myocardium is restored.
For pediatric myocardial protection, different cardioplegic solutions and strategies are currently clinically used. Both, the application and the composition of the solutions are borrowed from protection strategies for the adult heart w14,23,24x. However, the pediatric heart possesses several clinically relevant mechanisms for the conduct of congenital heart surgery. The preference for glucose and the low activity of 59nucleotidase contribute to the extensive ischemia tolerance of the pediatric heart. In contrast, the increased calcium sensitivity, the reduced enzyme activity of the free radical scavenging system, and unknown factors associated with the presence of cyanotic heart defects, may decrease ischemia tolerance and make the heart more prone to damage during reperfusion w13,25x. Recently, it could be demonstrated that preoperative cyanosis profoundly affects the protection of cardioplegic solutions on the myocardium w25x. In this study the authors showed that cold blood cardioplegia protected the hypoxic hearts in babies from ischemic and reoxygenation injury whereas crystalloid cardioplegia provides inadequate myocardial protection. Additionally, a terminal warm reperfusion (‘hot shot’) could improve myocardial function and preserve the adenine nucleotide pool in cyanotic children w25x. Our own results in Freiburg support this finding. However, evidence-based medicine criteria have not yet shown which cardioplegia is best w16x. Interestingly, most pediatric cardiac surgeons report similar results using different strategies of myocardial protection. It seems reasonable to assume that one technique in the hands of one surgeon may work, although it does not give the same results for another surgeon. Differences in operative techniques, operating times and quality of postoperative care may further camouflage possible differences. It is reasonable to conclude that the effects of these variations are 3
C. Schlensak / Multimedia Manual of Cardiothoracic Surgery / doi:10.1510/mmcts.2004.000729 minor with respect to extending the ischemia tolerance. Large randomized trials are required to evaluate the links between basic mechanisms and clinical practice of protection strategies for the pediatric heart. In summary, use of cardioplegia is the standard intraoperative care in most pediatric centers worldwide. Blood cardioplegia provides superior protection, especially in complex and longer cases. Evidencebased medicine criteria, however, have not yet shown which cardioplegia is best.
References w1x Bull C, Cooper J, Stark J. Cardioplegic protection of the child’s heart. J Thorac Cardiovasc Surg 1984;88:287–293. w2x Allen BS, Barth MJ, Ilbawi MN. Pediatric myocardial protection: an overview. Semin Thorac Cardiovasc Surg 2001;13:56–72. w3x Young JN, Choy IO, Silva NK, Obayashi DY, Barkan HE. Antegrade cold blood cardioplegia is not demonstrably advantageous over cold crystalloid cardioplegia in surgery for congenital heart disease. J Thorac Cardiovasc Surg 1997; 114:1002–1008. w4x Lacour-Gayet F, Clarke D, Jacobs J, Comas J, Daebritz S, Daenen W, Gaynor W, Hamilton L, Jacobs M, Maruszsewski B, Pozzi M, Spray T, Stellin G, Tchervenkov C, Mavroudis C, Aristotle Committee. The Aristotle score: a complexityadjusted method to evaluate surgical results. Eur J Cardiothorac Surg 2004;25:911–924. w5x Allen BS. Pediatric myocardial protection: where do we stand? J Thorac Cardiovasc Surg 2004; 128:11–13. w6x Lopaschuk GD, Spafford MA, Marsh DR. Glycolysis is predominant source of ATP production immediately after birth. Am J Physiol Heart Circ Physiol 1991;261:H1698–H1705. w7x Goodwin GW, Ahmad F, Doenst T, Taegtmeyer H. Energy provision from glycogen, glucose and fatty acids upon adrenergic stimulation of isolated working rat heart. Am J Physiol Heart Circ Physiol 1998;274:H1239–H1247. w8x Depre C, Vanoverschelde JL, Melin JA, Borgers M, Bol A, Ausma J, Dion R, Wijns W. Structural and metabolic correlates of the reversibility of chronic left ventricular ischemic dysfunction in humans. Am J Physiol Heart Circ Physiol 1995;268:H1265–H1275. w9x Makinde AO, Gamble J, Lopaschuk GD. Upregulation of 59-AMP-activated protein kinase is 4
w10x
w11x
w12x
w13x
w14x
w15x
w16x
w17x w18x
w19x
w20x
w21x
responsible for the increase in myocardial fatty acid oxidation rates following birth in the newborn rabbit. Circ Res 1997;80:482–489. Boland R, Martonosi A, Tillack TW. Developmental changes in the composition and function of sarcoplasmic reticulum. J Biol Chem 1974;249: 612–623. Bolling K, Kronen M, Allen BS, Ramon S, Wang T, Hartz RS, Feinberg H. Myocardial protection in normal and hypoxically stressed neonatal hearts: the superiority of hypocalcemic versus normocalcemic blood cardiopleiga. J Thorac Cardiovasc Surg 1996;112:1193–1200. Kronon MT, Allen BS, Hernan J, Halldorsson AO, Rahman S, Buckberg GD, Wang T, Ilbawi MN. Superiority of magnesium cardioplegia in neonatal myocardial protection. Ann Thorac Surg 1999; 68:2285–2291. Doenst T, Schlensak C, Beyersdorf F. Cardioplegia in pediatric cardiac surgery: do we believe in magic? Ann Thorac Surg 2003;75:1668–1677. Drinkwater DC, Laks H. Pediatric cardioplegic techniques. Semin Thorac Cardiovasc Surg 1993; 5:168–175. Kronon MT, Allen BS, Rahman S, Wang T, Tayyab NA, Bolling KS, Ilbawi MN. Reducing postischemic reperfusion damage in neonates using a terminal warm substrate-enriched blood cardioplegic reperfusate. Ann Thorac Surg 2000;70: 765–770. Bartels C, Gerdes A, Babin-Ebell J, Beyersdorf F, Boeken U, Doenst T, Feindt P, Heiermann M, Schlensak C, Sievers HH. Cardiopulmonary bypass: evidence or experience based? J Thorac Cardiovasc Surg 2002;124:20–27. Melrose DG, Dreyer B, Bentall MB, Baker JBE. Elective cardiac arrest. Lancet 1955;2:21. Follette DM, Mulder DG, Maloney JV, Buckberg GD. Advantages of blood cardioplegia over continuous coronary perfusion or intermittent ischemia. Experimental and clinical study. J Thorac Cardiovasc Surg 1978;76:604–619. Kirsch U, Rodewald G, Kalmar P. Induced ischemic arrest. Clinical experience with cardioplegia in open-heart surgery. J Thorac Cardiovasc Surg 1972;63:121–130. Bretschneider HJ, Hubner G, Knoll D, Lohr B, Nordbeck H, Spieckermann PG. Myocardial resistance and tolerance to ischemia: physiological and biochemical basis. J Cardiovasc Surg (Torino) 1975;16:241–260. Hearse DJ, Stewart DA, Braimbridge MV. Cellular protection during myocardial ischemia: the development and characterization of a procedure
C. Schlensak / Multimedia Manual of Cardiothoracic Surgery / doi:10.1510/mmcts.2004.000729 for the induction of reversible ischemic arrest. Circulation 1976;54:193–202. w22x Cecere G, Groom R, Forest R, Quinn R, Morton J. A 10-year review of pediatric perfusion practice in North America. Perfusion 2002;17:83–89. w23x Buckberg G. Update on current techniques of myocardial protection. Ann Thorac Surg 1995;60: 805–814. w24x Beyersdorf F, Kirsh M, Buckberg GD, Allen BS.
Warm glutamate/aspartate-enriched blood cardioplegic solution for perioperative sudden death. J Thorac Cardiovasc Surg 1992;104:1141– 1147. w25x Modi P, Suleiman MS, Reeves B, Pawade A, Parry AJ, Angelini GD, Caputo M. Myocardial metabolic changes during pediatric cardiac surgery: a randomized study of 3 cardioplegic techniques. J Thorac Cardiovasc Surg 2004;128:11–13.
5
Myocardial protection in congenital heart surgery Christian Schlensak* Department of Cardiovascular Surgery, University Hospital Freiburg, Hugstetter Strasse 55, 79106 Freiburg, Germany Modern pediatric cardiac surgery prides itself by performing primary surgical repair of cardiac anomalies. As a consequence, the majority of cases are nowadays performed in neonates and young infants. For the repair of intracardiac malformations the aorta is crossclamped and the heart is arrested (i.e. subjected to ischemia). Cardioplegic solution is administered routinely to arrest the contractile apparatus, decrease energy consumption and thereby increase ischemia tolerance. It is usually combined with hypothermia as another method to extend ischemia tolerance. In pediatric cardiac surgery several different cardioplegic solutions and strategies are currently used. For myocardial protection during crossclamp time either blood or crystalloid solution is administered into the aortic root or retrogradely into the coronary sinus, intermittently or as a single shot. The final concept for myocardial protection is highly dependent on the individual surgeon and his personal preference. There is currently no evidence in favor of one or the other technique. Thus, pediatric protection is currently experience-based.
Keywords: Blood cardioplegia; Myocardial protection; Pediatric cardiac surgery Introduction Although major advances in surgical techniques and technical aspects have been made in the field of congenital cardiac surgery, mortality remains high w1–3x. According to the EACTS congenital database w4x the 30-day mortality for all patients with congenital cardiac malformations is 5% (out of 24,637 patients in 2004) and exceeds 11% in neonates (out of 4,951 patients in 2004). Inappropriate myocardial protection during crossclamp time is still considered the main cause of death in the pediatric population w5x. It is interesting to note in this context, that the strategies for pediatric myocardial protection have remained relatively unchanged over the last decade. This is evident in the small number of publications available in the pediatric literature * Corresponding author: Tel.: q49-11-761-2702818; fax: q49-11761-2702368. E-mail: [email protected] 䉷 2005 European Association for Cardio-thoracic Surgery
compared to a large number on the same topic in adults. Adopting principles for myocardial protection established in adult patients for the pediatric patient population warrants caution because there are important structural and biochemical differences between the pediatric and adult myocardium. The main differences that relate to clinical practice are: 1. different pattern of substrate utilization 2. different activity levels of enzymes important for regeneration of ATP 3. the regulation of calcium metabolism. The pediatric heart utilizes mainly glucose as the oxidative substrate compared to fatty acids in the adult heart w6,7x. A shift towards glucose utilization is considered to improve ischemic tolerance w8x. A lower level of the enzyme 59nucleotidase as in the pediatric heart is associated with a higher end-ischemic level of AMP (that means preservation of the adenine 1
C. Schlensak / Multimedia Manual of Cardiothoracic Surgery / doi:10.1510/mmcts.2004.000729 cardioplegia was developed in Europe w19–21x) cardiac surgeons in North America use blood cardioplegia to protect the pediatric myocardium while most European centers are using crystalloid solution w22x. The principle difference between crystalloid and blood cardioplegia is that for blood cardioplegia the crystalloid solution is mixed with blood in a certain ratio (for example 1:4, crystalloid solution:autologous blood) while for crystalloid cardioplegia the solution is administered as is. Both, crystalloid and blood cardioplegia can be administered antegradely or retrogradely or as a single shot or intermittently. Photo 1. Set-up of the blood cardioplegic system of the heart-lung machine for pediatric myocardial protection. The roller pump (1) sucks blood from the oxygenator (2) and pumps it to the head exchanger (3). The line leading from the pump to the head exchanger has a Y-connector (4), which allows mixing of the blood with the crystalloid component of the cardioplegia (5). From the head exchanger the newly mixed blood cardioplegia is delivered to the patient (6). This cardioplegia delivery system is available from Sorin (MMCTSLink 76).
nucleotide pool), which is a prerequisite for recovery of function w9x. Finally, the calcium metabolism in the pediatric heart is immature. In the pediatric myocardium the sarcoplasmatic reticulum is underdeveloped and has reduced capacity for calcium storage w10x. In the pediatric heart the calcium is mainly provided by influx from the external space w10x. This difference makes it clear why the pediatric myocardium is so much more responsive to postischemic calcium overload. There are several reports describing the detrimental effects of cardioplegia solutions used for neonates containing normal or high calcium concentrations. Therefore most cardioplegia solutions used for the protection of the pediatric myocardium have lower than normal concentrations of calcium w2,11– 13x. Cardioplegic techniques Several techniques for myocardial protection in children have been proposed w1,2,14,15x. They differ in the cardioplegic solution used (crystalloid vs. blood), in the delivery root (antegrade vs. retrograde) and the frequency of its application (single shot vs. intermittent application). The final concept for myocardial protection is highly dependent on the individual surgeon and his personal preference. There is currently no evidence in favor of one or the other technique. Thus, pediatric protection is currently experience-based w16x. Most likely due to historical reasons (blood cardioplegia was developed in the US w17,18x and crystalloid 2
Surgical technique At our institution in Freiburg we use Buckberg’s cardioplegic solution w23x for myocardial protection in neonates and infants. The crystalloid solution is available (MMCTSLink 73). It is mixed through the delivery system of the heart-lung machine with autologous blood in a ratio 1:4 (crystalloid solution:autologous blood) prior to its application (Photo 1). If the aortic valve is competent the initial infusion is administered into the aortic root. After placement of a purse-string suture on the anterior part of the ascending aorta, the adventitia within the purse-string suture is incised with a No. 11 scalpel blade. Then the adventitia is gripped to both sides of the incision by a pair of forceps, after a No. 11 scalpel blade is advanced through the aortic wall within the pursestring suture. The hole can be closed by the adventitial flap. The cardioplegia cannula can then slide into the incision of the aortic wall and the purse-string suture can be snugged. After de-airing the cardioplegia line, the cannula is connected. The CPB is started and the ascending aorta is crossclamped and the myocardium arrested with cold blood cardioplegia (4 8C) (Photo 2). The initial infusion rate is 30 ml/kg body weight. Infusion pressure is not to exceed 80 mmHg for antegrade delivery. During aortic crossclamp time retrograde re-infusions are given every 20 min. Subsequent re-infusions are given retrogradely through a catheter which is placed into the coronary sinus. After placement of a purse-string suture around the ostium of the coronary sinus the catheter is connected to the cardioplegia line. Once the cannula is de-aired it is slowly advanced into the coronary sinus. The purse-string suture can be snugged and the cold cardioplegia re-infusion is delivered with 10 ml/kg body weight. This rate is several fold the volume used for cardioplegia of the adult heart, where infusion is
C. Schlensak / Multimedia Manual of Cardiothoracic Surgery / doi:10.1510/mmcts.2004.000729
Results Between January 1999 and June 2005 our strategy of myocardial protection was applied to 624 children presenting with the full spectrum of congenital cardiac malformations. Forty-two percent of our patients were less than 1 year of age. Mean aortic crossclamp time in all patients was 67"48 min (8–235 min). There were 6 hospital deaths (i.e. 1.0% overall mortality rate). None of them was related to inadequate myocardial protection. Our strategy of cardioplegia management did not increase the complexity of the procedure.
Discussion
Photo 2. Pediatric aortic root cannula and retrograde coronary sinus perfusion cannula with manual inflating cuff. The antegrade cardioplegia cannula (above) has a diameter of 4 French. The retrograde cannula (below) has a diameter of 6 French. Both cannulas are available from Medtronic DLP – MMCTSLink 74 and MMCTSLink 77).
Video 1. The right atrium is opened longitudinally in a standard manner. After placement of a purse-string suture around the ostium of the coronary sinus the catheter is connected to the cardioplegia line. Once the cannula is de-aired it is slowly advanced into the coronary sinus. The purse-string suture can be snugged and the cold cardioplegia re-infusion is delivered.
based on time rather than body weight. Infusion pressure is not to exceed 50 mmHg for retrograde delivery. The coronary sinus catheter will stay in place during the whole aortic crossclamp time (Video 1). This retrograde perfusion technique has the benefit, that the coronary arteries and the aortic root as well are sufficiently de-aired. If the aortic crossclamp time exceeds 60 min, a terminal warm substrate enriched infusion (‘hot shot’, 36 8C) is given through the coronary sinus catheter before the aorta is unclamped with a rate of 10 ml/kg body weight. During reperfusion the systemic reperfusion pressure is kept low (i.e. 30–40 mmHg) during the initial 5 min after blood flow to the myocardium is restored.
For pediatric myocardial protection, different cardioplegic solutions and strategies are currently clinically used. Both, the application and the composition of the solutions are borrowed from protection strategies for the adult heart w14,23,24x. However, the pediatric heart possesses several clinically relevant mechanisms for the conduct of congenital heart surgery. The preference for glucose and the low activity of 59nucleotidase contribute to the extensive ischemia tolerance of the pediatric heart. In contrast, the increased calcium sensitivity, the reduced enzyme activity of the free radical scavenging system, and unknown factors associated with the presence of cyanotic heart defects, may decrease ischemia tolerance and make the heart more prone to damage during reperfusion w13,25x. Recently, it could be demonstrated that preoperative cyanosis profoundly affects the protection of cardioplegic solutions on the myocardium w25x. In this study the authors showed that cold blood cardioplegia protected the hypoxic hearts in babies from ischemic and reoxygenation injury whereas crystalloid cardioplegia provides inadequate myocardial protection. Additionally, a terminal warm reperfusion (‘hot shot’) could improve myocardial function and preserve the adenine nucleotide pool in cyanotic children w25x. Our own results in Freiburg support this finding. However, evidence-based medicine criteria have not yet shown which cardioplegia is best w16x. Interestingly, most pediatric cardiac surgeons report similar results using different strategies of myocardial protection. It seems reasonable to assume that one technique in the hands of one surgeon may work, although it does not give the same results for another surgeon. Differences in operative techniques, operating times and quality of postoperative care may further camouflage possible differences. It is reasonable to conclude that the effects of these variations are 3
C. Schlensak / Multimedia Manual of Cardiothoracic Surgery / doi:10.1510/mmcts.2004.000729 minor with respect to extending the ischemia tolerance. Large randomized trials are required to evaluate the links between basic mechanisms and clinical practice of protection strategies for the pediatric heart. In summary, use of cardioplegia is the standard intraoperative care in most pediatric centers worldwide. Blood cardioplegia provides superior protection, especially in complex and longer cases. Evidencebased medicine criteria, however, have not yet shown which cardioplegia is best.
References w1x Bull C, Cooper J, Stark J. Cardioplegic protection of the child’s heart. J Thorac Cardiovasc Surg 1984;88:287–293. w2x Allen BS, Barth MJ, Ilbawi MN. Pediatric myocardial protection: an overview. Semin Thorac Cardiovasc Surg 2001;13:56–72. w3x Young JN, Choy IO, Silva NK, Obayashi DY, Barkan HE. Antegrade cold blood cardioplegia is not demonstrably advantageous over cold crystalloid cardioplegia in surgery for congenital heart disease. J Thorac Cardiovasc Surg 1997; 114:1002–1008. w4x Lacour-Gayet F, Clarke D, Jacobs J, Comas J, Daebritz S, Daenen W, Gaynor W, Hamilton L, Jacobs M, Maruszsewski B, Pozzi M, Spray T, Stellin G, Tchervenkov C, Mavroudis C, Aristotle Committee. The Aristotle score: a complexityadjusted method to evaluate surgical results. Eur J Cardiothorac Surg 2004;25:911–924. w5x Allen BS. Pediatric myocardial protection: where do we stand? J Thorac Cardiovasc Surg 2004; 128:11–13. w6x Lopaschuk GD, Spafford MA, Marsh DR. Glycolysis is predominant source of ATP production immediately after birth. Am J Physiol Heart Circ Physiol 1991;261:H1698–H1705. w7x Goodwin GW, Ahmad F, Doenst T, Taegtmeyer H. Energy provision from glycogen, glucose and fatty acids upon adrenergic stimulation of isolated working rat heart. Am J Physiol Heart Circ Physiol 1998;274:H1239–H1247. w8x Depre C, Vanoverschelde JL, Melin JA, Borgers M, Bol A, Ausma J, Dion R, Wijns W. Structural and metabolic correlates of the reversibility of chronic left ventricular ischemic dysfunction in humans. Am J Physiol Heart Circ Physiol 1995;268:H1265–H1275. w9x Makinde AO, Gamble J, Lopaschuk GD. Upregulation of 59-AMP-activated protein kinase is 4
w10x
w11x
w12x
w13x
w14x
w15x
w16x
w17x w18x
w19x
w20x
w21x
responsible for the increase in myocardial fatty acid oxidation rates following birth in the newborn rabbit. Circ Res 1997;80:482–489. Boland R, Martonosi A, Tillack TW. Developmental changes in the composition and function of sarcoplasmic reticulum. J Biol Chem 1974;249: 612–623. Bolling K, Kronen M, Allen BS, Ramon S, Wang T, Hartz RS, Feinberg H. Myocardial protection in normal and hypoxically stressed neonatal hearts: the superiority of hypocalcemic versus normocalcemic blood cardiopleiga. J Thorac Cardiovasc Surg 1996;112:1193–1200. Kronon MT, Allen BS, Hernan J, Halldorsson AO, Rahman S, Buckberg GD, Wang T, Ilbawi MN. Superiority of magnesium cardioplegia in neonatal myocardial protection. Ann Thorac Surg 1999; 68:2285–2291. Doenst T, Schlensak C, Beyersdorf F. Cardioplegia in pediatric cardiac surgery: do we believe in magic? Ann Thorac Surg 2003;75:1668–1677. Drinkwater DC, Laks H. Pediatric cardioplegic techniques. Semin Thorac Cardiovasc Surg 1993; 5:168–175. Kronon MT, Allen BS, Rahman S, Wang T, Tayyab NA, Bolling KS, Ilbawi MN. Reducing postischemic reperfusion damage in neonates using a terminal warm substrate-enriched blood cardioplegic reperfusate. Ann Thorac Surg 2000;70: 765–770. Bartels C, Gerdes A, Babin-Ebell J, Beyersdorf F, Boeken U, Doenst T, Feindt P, Heiermann M, Schlensak C, Sievers HH. Cardiopulmonary bypass: evidence or experience based? J Thorac Cardiovasc Surg 2002;124:20–27. Melrose DG, Dreyer B, Bentall MB, Baker JBE. Elective cardiac arrest. Lancet 1955;2:21. Follette DM, Mulder DG, Maloney JV, Buckberg GD. Advantages of blood cardioplegia over continuous coronary perfusion or intermittent ischemia. Experimental and clinical study. J Thorac Cardiovasc Surg 1978;76:604–619. Kirsch U, Rodewald G, Kalmar P. Induced ischemic arrest. Clinical experience with cardioplegia in open-heart surgery. J Thorac Cardiovasc Surg 1972;63:121–130. Bretschneider HJ, Hubner G, Knoll D, Lohr B, Nordbeck H, Spieckermann PG. Myocardial resistance and tolerance to ischemia: physiological and biochemical basis. J Cardiovasc Surg (Torino) 1975;16:241–260. Hearse DJ, Stewart DA, Braimbridge MV. Cellular protection during myocardial ischemia: the development and characterization of a procedure
C. Schlensak / Multimedia Manual of Cardiothoracic Surgery / doi:10.1510/mmcts.2004.000729 for the induction of reversible ischemic arrest. Circulation 1976;54:193–202. w22x Cecere G, Groom R, Forest R, Quinn R, Morton J. A 10-year review of pediatric perfusion practice in North America. Perfusion 2002;17:83–89. w23x Buckberg G. Update on current techniques of myocardial protection. Ann Thorac Surg 1995;60: 805–814. w24x Beyersdorf F, Kirsh M, Buckberg GD, Allen BS.
Warm glutamate/aspartate-enriched blood cardioplegic solution for perioperative sudden death. J Thorac Cardiovasc Surg 1992;104:1141– 1147. w25x Modi P, Suleiman MS, Reeves B, Pawade A, Parry AJ, Angelini GD, Caputo M. Myocardial metabolic changes during pediatric cardiac surgery: a randomized study of 3 cardioplegic techniques. J Thorac Cardiovasc Surg 2004;128:11–13.
5
