Retrograde continuous warm blood cardioplegia

Retrograde Continuous Warm Blood Cardioplegia: A New Concept in Myocardial Protection Tomas A. Salerno, MD, James P. Houck, MD, Carlos A. M. Barrozo, MD, Anthony Panos, MD, George T. Christakis, MD, James G. Abel, MD, and Samuel V. Lichtenstein, MD Division of Cardiovascular Surgery, St. Michael’s Hospital, University of Toronto, Toronto, Ontario, Canada

This report presents the results in our first clinical series of patients receiving continuous warm blded cardioplegia through the coionary sinus. Warm oxygenated blood cardioplegia has certain theoretical advantages, such as continuously supplying oxygen and substrates to the arrested heart while avoiding the side effects of hypothermia. Retrograde infusion of cardioplegia also offers certain advantages (eg, in valve operations and in patients with severe coronary artery disease) that are complementary to warm blood cardioplegia. Retrograde warm blood cardioplegia was used in 113 consecutive

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etrograde coronary sinus cardioplegia has been shown to be safe and effective [l-31. Until recently, its use was somewhat limited because of the difficulties and danger involved in cannulating the coronary sinus for cardioplegia delivery. In 1990, Drinkwater and associates [4] reported the use of a coronary sinus catheter with a self-inflating balloon, which has simplified the technique of coronary sinus cardioplegia. This catheter can usually be inserted into the coronary sinus without the need of direct visualization, and therefore, only rarely will bicaval cannulation and snaring be necessary. ~~

For editorial comment, see page 180. The purpose of this study is to report the results in our first clinical series of patients undergoing a cardiac operation and receiving continuous warm blood cardioplegia through the coronary sinus with warm body perfusion during cardiopulmonary bypass (CPB).

Material and Methods Patient Population Data were obtained from a prospectively collected database as well as a record review of 113 patients who underwent various cardiac procedures using retrograde continuous warm blood cardioplegia and normothermic CPB during a 5-month period. This population consisted of 85 men and 28 women with a mean age of 61 years (range, 21 to 77 years). It is important to note that 25 Accepted for publication Oct 16, 1990. Address reprint requests to Dr Salerno, St. Michael’s Hospital, Rrn 3058, 30 Bond St, Toronto, Ont, Canada M5B 1W8.

0 1991 by The Society of Thoracic Surgeons

patients (85 men and 28 women with a mean age of 61 years) undergoing various procedures. Three percent of the patients died, 7% needed transient intraaortic balloon pump support, 6% had evidence of perioperative myocardial infarction, and 96% had spontaneous return of rhythm. There were no coronary sinus injuries. This new technique of retrograde continuous warm blood cardioplegia is a simple, safe, and reliable method of myocardial protection that may change the way we currently protect the heart intraoperatively. (Ann Thoruc Surg 1991;51:245-7)

patients (22%) were more than 70 years old, and 33 (51%) of the patients having myocardial revascularization only were operated on urgently. Furthermore, 44 (39%)of the patients were in New York Heart Association class IV, and 22 (34%) of the patients undergoing myocardial revascularization had had a previous myocardial infarction. Six patients (5%) were operated on urgently for endocarditis. The preoperative diagnoses are listed in Table 1.

Operative Technique After median sternotomy and heparinization, standard cannulation techniques through the ascending aorta and right atrium were used to complete the CPB circuit. An aortic anterograde cardioplegia cannula (DLP Inc) was placed, and before the initiation of CPB, the retrograde coronary sinus catheter (Research Medical Inc) was positioned using closed transatrial technique. Full CPB was initiated and maintained at normothermia (37°C). While the heart was beating, high-potassium warm blood cardioplegia (resulting from mixing blood 4:l with highpotassium Fremes’ solution*)was infused. The aorta was then clamped. When the heart was arrested, the cardioplegia line was switched to the fluid-filled retroplegia cannula, and lowpotassium warm blood cardioplegia (resulting from a mixture of blood 4:l with low-potassium Fremes’ solution, which has the same ingredients as the highpotassium solution except KCL = 30 mEq/L) was then infused continuously, with the infusion pressure at the *High-potassium Fremes’ solution comprises the following: 500 mL of 5% dextrose in water; KCI, 50 mEq; MgSO,, 9 mEq; THAM (trihydroxymethylaminornethane), 6 mEq; citrate-phosphate-dextrosesolution, 10 mL; osmolality, 425 m o s d l ; pH, 7.95.

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Ann Thorac Surg 1991;51:245-7

Table 1. Preoperative Diagnoses No. of

Diagnosis

Patients

Coronary artery disease Stable angina Unstable angina Failed angioplasty Mitral valve disease Aortic valve disease Mitral valve Aortic valve

+ coronary artery disease

+ coronary artery disease Multiple-valve disease Atrial septal defect Cor triatriatum + endocarditis

65 32 28 5 12 28 1 1

4 1 1

cannula tip maintained at less than 40 mm Hg. The mean flow of cardioplegia in the coronary sinus was 122 mL/min (range, 79 to 234 mL/min). Cardioplegic flow rates varied, and the total administered volume of cardioplegia ranged from 300 to 5,200 mL. The total amount of potassium delivered ranged from 23 to 177 mEq with a mean of 67 mEq. Hyperkalemia was not a clinically significant problem in any patient. The aortic root was vented throughout the cross-clamp period, and retrograde perfusion was assured by noting the engorged oxygenated cardiac veins as well as the return of dark blood through the vent in the aortic root.

Results The coronary sinus was easily cannulated by the closed transatrial technique in 111 patients (98%).This was not possible in 2 patients (2%), and they required bicaval cannulation and insertion of the retroplegia cannula under direct vision. Placement was facilitated by insertion before the initiation of CPB, and neither major arrhythmias nor hypotension was encountered. The technique was used in a wide variety of cardiac procedures, as indicated in Table 2. No anomalies of the coronary sinus were encountered. Myocardial revascularization occasionally required intermittent interruption of cardioplegic flow for short periods to perform the anastomoses. There were three deaths (3%): a 67-year-old woman sustained massive myocardial necrosis secondary to coronary embolization after aortic valve replacement, and 2 male patients who underwent urgent coronary artery bypass grafting died in the intensive care unit in the early postoperative period secondary to graft failures. Few complications were encountered in this group of patients representing our preliminary experience with this technique. Eight patients (7%) required transient intraaortic balloon pump support for low-output syndrome. Seven patients (6%) had electrocardiographic or cardiac isoenzyme evidence of perioperative myocardial infarction, but there were no subsequent clinical sequelae.

Six patients (5%) were returned to the operating room because of bleeding. We observed that 96% of the patients had spontaneous return of rhythm and did not require defibrillation. One patient undergoing aortic valve replacement had heart block and required a pacemaker. There were no coronary sinus injuries.

Comment Rosenkranz and colleagues suggested that warm induction of cardiac arrest with blood cardioplegia would resuscitate the damaged heart experimentally [5] and clinically [6]. Teoh and associates [7] demonstrated the beneficial effects of terminal warm blood cardioplegia (the so-called hot shot), as suggested by Lazar and co-workers [8]. At the University of Toronto, following Bonfim and co-authors [9], we [lo] have used continuous cold (15" to 20°C) oxygenated blood cardioplegia for the last 7 years. Lichtenstein and associates in our group [ l l ] introduced the concept of continuous oxygenated warm blood cardioplegia (warm heart surgery) and recently reported their clinical experience. The advantages of this method are evident when one considers that even short periods of warm blood cardioplegia, either immediately after aortic clamping [6] or immediately before declamping [7, 81, are beneficial to the heart. Further, it is perhaps time to reassess the effects of hypothermia, introduced clinically by Bigelow and coworkers [12]. It is beyond the scope of this article to review the subject of hypothermia. It is sufficient to note that there are many side effects of hypothermia, such as its effects on membrane stability [13], calcium sequestration [14], glucose utilization [15], adenosine triphosphate generation and utilization [16], tissue oxygen uptake [17], pH [MI, cellular osmotic homeostasis [19], and the adenosine triphosphatase system [20], as observed during deep hypothermia.

Table 2. Operative Procedures No. of

Patients

Procedure CABG CABG with LIMA Redo CABG CABG + mitral valve replacement CABG + aortic valve replacement Mitral valve repair Mitral valve replacement Redo mitral valve replacement Aortic valve replacement Redo aortic valve replacement Multiple-valve replacement or repair Atrial septal defect closure Cor triatriatum + mitral valve replacement CABG = coronary artery bypass grafting; mary artery.

27 36 2 1 1 1

7 4

27 1

4 1 1

LIMA = left internal mam-

A n n Thorac Surg 1991;51:245-7

Delivery of cardioplegia through the coronary sinus route is not a new technique [21]. Different solutions have been used, such as intermittent cold crystalloid or blood cardioplegia, delivered through different routes, such as direct cannulation and snaring of coronary sinus ostium and bicaval cannulation and snaring with infusion into the right atrium with the aorta and pulmonary artery clamped. Drinkwater and co-workers [4]simplified the technique for catheter placement in the coronary sinus, which is now done in a closed fashion (ie, blindly) through a pursestring in the right atrium (usually without the need of bicaval cannulation or snaring) using a catheter with a self-inflating balloon. We believe this is one of the first reports of the use of continuous warm blood cardioplegia through the coronary sinus. In this preliminary experience, the safety and effectiveness of the technique appear to be demonstrated. This technique allows performance of any kind of cardiac operation (except operation for anomolous coronary sinus) without the need of a single period of ischemia. The technique has been applied for coronary artery disease, valvar disease, congenital conditions, and combined operations (valve procedure and coronary artery bypass grafting) with excellent results. Additional animal and clinical studies are currently underway in our laboratories to further delineate the effects of warm continuous oxygenated blood cardioplegia through the coronary sinus route. In our series of patients, 22% were more than 70 years old, and 39% were in New York Heart Association class N . Also, of the patients undergoing bypass grafting, 51% had urgent revascularization. The preliminary clinical results in this difficult group of patients suggest that retrograde continuous warm blood cardioplegia may be a promising technique for high-risk operations. Dr Panos is a Fellow of the Medical Research Council of Canada. Supported by grant MA-8044 from the Medical Research Council of Canada.

References Partington MT, Acar C, Buckberg GD, et al. Studies of retrograde cardioplegia. I. Capillary blood flow distribution to myocardium supplied by open and occluded arteries. J Thorac Cardiovasc Surg 1989;97605-12. Partington MT, Acar C, Buckberg GD, et al. Studies of retrograde cardioplegia. 11. Advantages of antegradehetrograde cardioplegia to optimize distribution in jeopardized myocardium. J Thorac Cardiovasc Surg 1989;9761?-22. Menasch6 P, Subayi J-8, Piwnica A. Retrograde coronary sinus cardioplegia for aortic valve operations: a clinical report on 500 patients. Ann Thorac Surg 1990;49:556-64. Drinkwater DC, Laks H, Buckberg GD. A new simplified

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method of optimizing cardioplegia delivery without right heart isolation. J Thorac Cardiovasc Surg 1990;100:56-64. 5. Rosenkranz ER, Vinten-Johansen J, Buckberg GD, et al. Benefits of normothermic induction of blood cardioplegia in energy-depleted hearts with maintenance of arrest by multidose cold blood cardioplegic infusions. J Thorac Cardiovasc Surg 1982;84:667-77. 6. Rosenkranz ER, Buckberg GD, Laks H, Mulder DG. Warm induction of cardioplegia with glutamate-enriched blood in coronary patients with cardiogenic shock who are dependent on inotropic drugs and intra-aortic balloon support. Initial experience and operative strategy. J Thorac Cardiovasc Surg 1983;86:507-18. 7. Teoh KH, Christakis GT, Weisel RD, et al. Accelerated myocardial metabolic recovery with terminal warm blood cardioplegia. J Thorac Cardiovasc Surg 1986;91:888-95. 8. Lazar HL, Buckberg GD, Manganaro AJ, et al. Reversal of ischemic damage with secondary blood cardioplegia. J Thorac Cardiovasc Surg 1979;78:688-97. 9. Bonfim V, Kaijser L, Bendz R, et al. Myocardial protection during aortic valve replacement. Cardiac metabolism and enzyme release following continuous blood cardioplegia. Scand J Thorac Cardiovasc Surg 1981;15:141-7. 10. Panos A, Christakis GT, Lichtenstein SV, Wittnich C, ElDalati H, Salerno TA. Operation for acute postinfarction mitral insufficiency using continuous oxygenated blood cardioplegia. Ann Thorac Surg 1989;48:816-9. 11. Lichtenstein SV, Ashe KA, Cusimano RJ, et al. Warm heart surgery. J Thorac Cardiovasc Surg (in press). 12. Bigelow WG, Callaghan JC, Hopps JA. General hypothermia for experimental intracardiac surgery. Ann Surg 1950;132: 531. 13. McMurchie EJ, Raison JK, Cairncross KD. Temperatureinduced phase changes in membranes of heart: a contrast between the thermal response of poikiIotherms and homeotherms. Comp Biochem Physiol [B] 1973;44:1017-26. 14. Sakai T, Kuihara S. Effect of rapid cooling on mechanical and electrical responses in ventricular muscle of the guinea pig. J Physiol (Lond) 1985;361:361-78. 15. Fuhrman GJ, Furrman FA. Utilization of glucose by the hypothermic rat. Am J Physiol 1963;295:181-3. 16. Lyons JM, Raison JK. A temperature-induced transition in mitochondria1 oxidation: contrast between cold and warmblooded animals. Comp Biochem Physiol 1970;37495-511. 17. Magovern GJ Jr, Flaherty JT, Gott VL, et al. Failure of blood cardioplegia to protect myocardium at lower temperatures. Circulation 1982;(Suppl 1):60-7. 18. Rahn H, Reeves RB, Howell BJ. Hydrogen ion regulation, temperature and evolution. Am Rev Respir Dis 1975;112:16572. 19. MacKnight AC, Leaf A. Regulation of cellular volume. Physiol Rev 1977;57:510-73. 20. Martin DR, Scott DF, Downer GL, et al. Primary cause of unsuccessful liver and heart preservation. Cold sensitivity of the ATP-ase system. Ann Surg 1972;175:111-7. 21. Lillehei CW, DeWall RA, Gott VL, et al. The direct vision correction of calcific aortic stenosis by means of a pumpoxygenator and retrograde coronary sinus perfusion. Dis Chest 1956;30:12332.