Análise comparativa de dois métodos de proteção miocárdica em pacientes de alto risco para cirurgia de revascularização do míocárdio

Reis Filho, Fernando Antônio Roquete; Lima, Luiz Cláudio Moreira; Mota, Giancarlo Grossi; Gonçalves, Leonardo A; Gomes, Maurício C; Bernardes, Rodrigo de Castro; Rabelo, Raul Corrêa

doi:10.1590/S0102-76381996000400004

Resumos

OBJETIVO: Comparar a tradicional proteção miocárdica oferecida pela cardioplegia cristalóide gelada infundida na aorta associada à hipotermia sistêmica e ao pinçamento intermitente da aorta (Grupo I), à cardioplegia sangüínea normotérmica com indução pela aorta e manutenção por via retrógrada (seio coronário) associada a normotermia sistêmica. CASUÍSTICA E MÉTODOS: No período de maio de 1992 a maio de 1994, foram selecionados de forma consecutiva, não randomizada, de acordo com pré-requisitos que acrescentavam alta morbi-mortalidade à cirurgia de revascularização miocárdica (CRVM), dois grupos de 50 pacientes. Todos os pacientes selecionados apresentavam: instabilidade ou intratabilidade clínica, mais de três ramos arteriais coronários, ou tronco de coronária esquerda ocluídos, ou gravemente obstruídos e grave disfunção ventricular esquerda de etiologia isquêmica. RESULTADOS: Os grupos foram semelhantes quanto às variáveis pré-operatórias. O Grupo II teve maior média de enxertos (3,82x3,40), conseqüentemente maior tempo de pinçamento aórtico (70,74x62,6 min) e maior tempo de circulação extracorpórea (CEC) (97,50x93,86 min). O Grupo I teve maior incidência de fibrilação ventricular após despinçamento aórtico (20%x4%) p=0,032, maior necessidade de inotrópicos para sair da CEC (18%x12%) maior necessidade de assistência circulatória (14%x8%), maior incidência de infarto agudo do miocárdio (20%x12%); teve ainda menor incidência de vetilação mecânica prolongada (6%x12%), maior mortalidade imediata (12%x6%), hospitalar (14%x10%) e global (26%x16%) e maior incidência de óbitos de causas cardíacas (12%x4%). CONCLUSÃO: A comparabilidade dos grupos ficou prejudicada pela maior média de enxertos do Grupo II, conferindo maior gravidade a este grupo. Mesmo assim, os resultados deste grupo foram superiores aos do Grupo I, embora isto não tenha sido corroborado pela análise estatística. Estes resultados, associados à impressão clínica, o aprimoramento técnico e o reconhecimento das limitações do método nos obrigaram a adotá-lo como forma de proteção miocárdica neste grupo específico de pacientes.

Parada cardíaca induzida; Revascularização miocárdica; Revascularização miocárdica

OBJECTIVE: To compare the tradicional myocardial protection achieved by crystalloid cold cardioplegia, which is induced through the aortic root, associated to systemic hypothermia and intermitent aortic cross-clamping (Group I) to warm blood cardioplegia using induction through the aortic root but retrograde maintenance through the coronary sinus, associated to systemic normothermia. METHODS AND MATERIAL: During the period ranging from May 1992 to May 1994, two groups of 50 patients were selected consecutively, but not randomized, according to requirements that increased the morbidity and mortality associated to the Coronary Artery Bypass Graft (CABG). All selected patients presented at the time clinical instability, more than three coronary arteries (or the left main coronary artery) occluded or severely suboccluded, associated with severe LV dysfunction of ischemic ethiology. RESULTS: The two groups were comparable according to the variabilities found in the period just prior to the surgery. Group II had a larger amount of grafts (3.82x3.40), consequently a longer period of aortic cross-clamping (70.74x62.06 min) and a longer time in cardiopulmonary bypass (CPB) (97.5x93.8 min). Group I, in average, needed more inotropic agents for the weaning process from CPB, more use of mechanical assist devices and showed a bigger incidence of acute myocardial infarction as well as ventricular fibrilation after aortic cross-clamp release. This group also had less incidence of prolonged mechanical ventilation, greater early and global mortality, and also a larger number of deaths due to other cardiac causes. CONCLUSION: The two groups were not comparable due to the larger number of grafts in Group II turning them more critical than Group I. Nervertheless, the results from Group II were superior to Group I, even though the statistic analysis do not corroborate those results. That, associated with clinical data, technical improvement and recognizing the limitations of the procedure, made us use it in this specific group of patients.

Heart arrest, induced; Myocardial revascularization; Myocardial revascularization

ARTIGOS ORIGINAIS

Análise comparativa de dois métodos de proteção miocárdica em pacientes de alto risco para cirurgia de revascularização do míocárdio

Comparative analysis of two methods of myocardial protection

Fernando Antônio Roquete Reis Filho; Luiz Cláudio Moreira Lima; Giancarlo Grossi Mota; Leonardo A. Gonçalves; Maurício C. Gomes; Rodrigo de Castro Bernardes; Raul Corrêa Rabelo

Do Instituto do Coração do Hospital Madre Tereza

^{Endereço para correspondência} Endereço para correspondência: Fernando Antônio Reis Filho Av. Raja Gabaglía, 1002 - Gutierrez Belo Horizonte, MG, Brasil. CEP: 30380-090 Tel. 337-5933

RESUMO

OBJETIVO: Comparar a tradicional proteção miocárdica oferecida pela cardioplegia cristalóide gelada infundida na aorta associada à hipotermia sistêmica e ao pinçamento intermitente da aorta (Grupo I), à cardioplegia sangüínea normotérmica com indução pela aorta e manutenção por via retrógrada (seio coronário) associada a normotermia sistêmica.

CASUÍSTICA E MÉTODOS: No período de maio de 1992 a maio de 1994, foram selecionados de forma consecutiva, não randomizada, de acordo com pré-requisitos que acrescentavam alta morbi-mortalidade à cirurgia de revascularização miocárdica (CRVM), dois grupos de 50 pacientes. Todos os pacientes selecionados apresentavam: instabilidade ou intratabilidade clínica, mais de três ramos arteriais coronários, ou tronco de coronária esquerda ocluídos, ou gravemente obstruídos e grave disfunção ventricular esquerda de etiologia isquêmica.

RESULTADOS: Os grupos foram semelhantes quanto às variáveis pré-operatórias. O Grupo II teve maior média de enxertos (3,82x3,40), conseqüentemente maior tempo de pinçamento aórtico (70,74x62,6 min) e maior tempo de circulação extracorpórea (CEC) (97,50x93,86 min). O Grupo I teve maior incidência de fibrilação ventricular após despinçamento aórtico (20%x4%) p=0,032, maior necessidade de inotrópicos para sair da CEC (18%x12%) maior necessidade de assistência circulatória (14%x8%), maior incidência de infarto agudo do miocárdio (20%x12%); teve ainda menor incidência de vetilação mecânica prolongada (6%x12%), maior mortalidade imediata (12%x6%), hospitalar (14%x10%) e global (26%x16%) e maior incidência de óbitos de causas cardíacas (12%x4%).

CONCLUSÃO: A comparabilidade dos grupos ficou prejudicada pela maior média de enxertos do Grupo II, conferindo maior gravidade a este grupo. Mesmo assim, os resultados deste grupo foram superiores aos do Grupo I, embora isto não tenha sido corroborado pela análise estatística. Estes resultados, associados à impressão clínica, o aprimoramento técnico e o reconhecimento das limitações do método nos obrigaram a adotá-lo como forma de proteção miocárdica neste grupo específico de pacientes.

Descritores: Parada cardíaca induzida, métodos. Revascularização miocárdica, fatores de risco. Revascularização miocárdica, estudo comparativo.

ABSTRACT

OBJECTIVE: To compare the tradicional myocardial protection achieved by crystalloid cold cardioplegia, which is induced through the aortic root, associated to systemic hypothermia and intermitent aortic cross-clamping (Group I) to warm blood cardioplegia using induction through the aortic root but retrograde maintenance through the coronary sinus, associated to systemic normothermia.

METHODS AND MATERIAL: During the period ranging from May 1992 to May 1994, two groups of 50 patients were selected consecutively, but not randomized, according to requirements that increased the morbidity and mortality associated to the Coronary Artery Bypass Graft (CABG). All selected patients presented at the time clinical instability, more than three coronary arteries (or the left main coronary artery) occluded or severely suboccluded, associated with severe LV dysfunction of ischemic ethiology.

RESULTS: The two groups were comparable according to the variabilities found in the period just prior to the surgery. Group II had a larger amount of grafts (3.82x3.40), consequently a longer period of aortic cross-clamping (70.74x62.06 min) and a longer time in cardiopulmonary bypass (CPB) (97.5x93.8 min). Group I, in average, needed more inotropic agents for the weaning process from CPB, more use of mechanical assist devices and showed a bigger incidence of acute myocardial infarction as well as ventricular fibrilation after aortic cross-clamp release. This group also had less incidence of prolonged mechanical ventilation, greater early and global mortality, and also a larger number of deaths due to other cardiac causes.

CONCLUSION: The two groups were not comparable due to the larger number of grafts in Group II turning them more critical than Group I. Nervertheless, the results from Group II were superior to Group I, even though the statistic analysis do not corroborate those results. That, associated with clinical data, technical improvement and recognizing the limitations of the procedure, made us use it in this specific group of patients.

Descriptors: Heart arrest, induced, methods. Myocardial revascularization, risk factors. Myocardial revascularization, comparative study.

Texto completo disponível apenas em PDF.

Full text available only in PDF format.

Trabalho realizado no Instituto do Coração do Hospital Madre Tereza. Belo Horizonte, MG, Brasil. Apresentado ao 23º Congresso Nacional de Cirurgia Cardíaca. Recife, PE, 20 a 23 de março, 1996.

¹
Melrose D G, Dreyer B, Bentall H H, Baker J B E - Elective cardiac arrest. Lancet 1955; 2: 21-2.
²
Blanco G, Adam A, Fernandez A - A direct experimental approach to the aortic valve: II. Acute retroperfusion of coronary sinus. J Thorac Surg 1956; 32: 171.
³
Gott V L, Gonzales J L, Zuhdi M N - Retrograde perfusion of coronary sinus for direct vision aortic surgery. Surg Gynecol Obstet 1957; 104: 319.
⁴
Lillehey C N, De Wall R A, Gott V L, Varco R L - The direct vision correction of calcified aortic stenosis by means of a pump-oxygenator and retrograde coronary sinus perfusion. Dis Chest 1956; 30: 123.
⁵
Solorzano J, Taitelbaum G, Chiu R C - Retrograde coronary sinus perfusion for myocardial protection during cardiopulmonary bypass. Ann Thorac Surg 1978; 25: 201-8.
⁶
Menasché P, Kural S, Fauchet M et al. - Retrograde coronary sinus perfusion: a safe alternative for ensuring cardioplegic delivery in aortic valve surgery. Ann Thorac Surg 1982; 34: 647-58.
⁷
Menasché P & Pwinica A H - Retrograde coronary sinus perfusion. In: Roberts A J, ed. Myocardial protection during cardiac surgery. New York: Marcel Dekker, 1987: 251-62.
⁸
Shapira N, Lemole G M, Spagna P M, Bonner F J, Fernandez J, Morse D - Antegrade and retrograde infusion of cardioplegia: assessment by thermovision. Ann Thorac Surg 1987; 43: 92-7.
⁹
Lazar H L - Coronary sinus interventions during cardiac surgery. Ann Thorac Surg 1988; 46: 475-82.
¹⁰
Chitwood W R - Myocardial protection by retrograde cardioplegia: coronary sinus and right atrial methods. In: Cardiac surgery: state of art reviews, vol.2. Philadelphia: Hanley and Belfus, 1988: 197-218.
¹¹
Sutter F P, Goldman S M, Clancy M et al. - Continuous retrograde blood cardioplegia. Ann Thorac Surg 1991; 51: 136-7.
¹²
Bolling S F, Flaherty J T, Bulkley B H, Gott V L, Gradner T J - Improved myocardial preservation during global ischemia by continuous retrograde coronary sinus perfusion. J Thorac Cardiovasc Surg 1983; 86: 659-66.
¹³
Gundry S R & Hirsh M M - A comparison of retrograde versus antegrade cardioplegia in the presence of coronary artery obstruction. Ann Thorac Surg 1984; 38: 124-7.
¹⁴
Horneffer P J, Gott V L, Gardner T J - Retrograde coronary sinus perfusion prevents infarct extension during intraoperative global ischemic arrest. Ann Thorac Surg 1986; 42: 132-42.
¹⁵
Masuda M, Yonega K, Shiki K, Morita S, Kohno H, Tokunaga K - Myocardial protection in coronary occlusion by retrograde cardioplegic perfusion via the coronary sinus in dogs. J Thorac Cardiovasc Surg 1986; 92: 255-63.
¹⁶
Partington M T, Acar C, Buckberg G D, Julia P, Kofsky E R, Bugy H I - Studies of retrograde cardioplegia: I. Capillary blood flow distribution to myocardium supplied by open and occluded arteries. J Thorac Cardiovasc Surg 1989; 97: 605-12.
¹⁷
Haan C, Lazar H L, Bernard S, Rivers S, Zallnick J, Shemin R J - Superiority of retrograde cardioplegia after acute coronary occlusion. Ann Thorac Surg 1991; 51: 408-12.
¹⁸
Schaper j, Walter P, Scheld H, Hehrlein F - The effects of retrograde perfusion of cardioplegic solution in cardiac operations. J Thorac Surg 1985; 90: 882-7.
¹⁹
Snyder H E, Smithwick W, Wingard T, Agnew R C - Retrograde coronary sinus perfusion. Ann Thorac Surg 1988; 46: 389-90.
²⁰
Fiore A C, Naunheim K S, Kaiser G C et al. - Coronary sinus versus aortic root perfusion with blood cardioplegia in elective myocardial revascularization. Ann Thorac Surg 1989; 47: 684-8.
²¹
Lichtenstein S V, Ashe K A, Dalati H E, Cusimano R J, Panos A, Slutsky A S - Warm heart surgery. J Thorac Cardiovasc Surg 1991; 101: 269-74.
²²
Buckberg G D - Antegrade/retrograde blood cardioplegia to ensure cardioplegic distribution: operative techniques and objectives. J Card Surg 1989; 4: 216-38.
²³
Kalmbach T & Bhayana J N - Cardioplegia delivery by combined aortic root and coronary sinus perfusion. Ann Thorac Surg 1989; 47: 316-7.
²⁴
Drinkwater D C, Laks H, Buckberg G D - A new simplified method of optimizing cardioplegic delivery without righ heart isolation. J Thorac Cardiovasc Surg 1990; 100: 56-64.
²⁵
Drinkwater D C, Cushen C K, Laks H, Buckberg G D - The use of combined antegrade/retrograde infusion of blood cardioplegic solution in pediatric patients undergoing heart operations. J Thorac Cardiovasc Surg 1992; 104: 1349-55.
²⁶
Kennedy J W, Kaiser G C, Fisher L D et al. - Clinical and angiographic predictors of operative mortality from the Collaborative Study in Coronary Artery Surgery (CASS). Circulation 1981; 63: 793-802.
²⁷
Naunheim K S, Fiori A C, Wadley S S - The changing profile of the patient undergoing coronary artery bypass surgery. J Am Coll Cardiol 1988; 11: 494-8.
²⁸
Hearse D J, Braimbridge M V, Jynge P - Ischemia and reperfusion: the progression and prevention of tissue injury. In: Protection of the ischemic myocardium: cardioplegia. New York: Raven Press, 1981: 21.
²⁹
Roberts A J - Myocardial protection in cardiac surgery. New York: Marcel Dekker, 1987.
³⁰
Macmanus Q, Grunkemeier G, Lambert L, Dietl C, Starr A - Aortic valve replacement and aorta-coronary bypass surgery: results with perfusion of proximal and distal coronary arteries. J Thorac Cardiovasc Surg 1978; 75: 865-9.
³¹
Buckberg G D - A proposed "solution" to the cardioplegic controversy. J Thorac Cardiovasc Surg 1979; 77: 803-15.
³²
Chiu R C J, Blundell P E, Scott H J, Cain S - The importance of monitoring intramyocardial temperature during hypothermic myocardial protection. Ann Thorac Surg 1979; 28: 317-22.
³³
Oldham H N, Jones R H, Harris C C, Howe W R, Goodrich J k, Sabiston Jr. D C - Intraoperative relationships between regional myocardial distribution of bypass graft flow and the coronary collateral circulation. J Thorac Cardiovasc Surg 1979; 77: 32-8.
³⁴
Hilton C J, Teubl W, Acker M et al - Inadequate cardioplegic protection with obstructed coronary arteries. Ann Thorac Surg 1979; 28: 323-34.
³⁵
Fishman N H & Abouav J - Myocardial temperature differences as a guide to the order of coronary artery bypass anastomoses in high-risk patients. Am J Surg 1980; 140: 92-8.
³⁶
Ekroth R, Berggren H, Sudow G, Wojciechowski J, Zackrisson B F, Willian-Olsson G - Thermographic demonstration of uneven myocardial cooling in patients with coronary lesions. Ann Thorac Surg 1980; 29: 341-5.
³⁷
Daggett W M, Jacocks M A, Coleman W S, Jonhson R G, Lowenstein E, Vander Salm T J - Myocardial temperature mapping: improved intraoperative myocardial preservation. J Thorac Cardiovasc Surg 1981; 82: 883-8.
³⁸
Becker H, Vinten-Johansen J, Buckberg G D, Follette D M, Robertson J M - Critical importance of ensuring cardioplegic delivery with coronary stenosis. J Thorac Cardiovasc Surg 1981; 81: 507-15.
³⁹
Grodin C M, Helias J, Vonhe P R, Robert P - Influence of a critical coronary artery stenosis on myocardial protection through cold cardioplegia. J Thorac Cardiovasc Surg 1981; 82: 608-12.
⁴⁰
Landymore R W, Tice D, Trehan N, Spencer F - Importance of topical hypothermia to ensure uniform myocardial cooling during coronary artery bypass. J Thorac Cardiovasc Surg 1981; 82: 832-6.
⁴¹
Heineman F W, MacGregor D C, Wilson J G, Ninomiya J - Regional and transmural myocardial temperature distribuition in cold chemical cardioplegia. J Thorac Cardiovasc Surg 1981; 81: 851-9.
⁴²
Robertson J M, Buckberg G D, Viten-Johansen J, Leaf J D - Comparison of distribution beyond coronary stenosis of blood and asanguineous cardioplegic solutions. J Thorac Cardiovasc Surg 1983; 82: 80-6.
⁴³
Rosenkranz E R, Vinten-Johansen J, Buckberg G D, Okanoto F, Edward H, Bugyi H - Benefits of normothermic induction of blood cardioplegia in energy-depleted hearts, with maintenance of arrest by multidose cold blood cardioplegia infusions. J Thorac Cardiovasc Surg 1982; 84: 667-77.
⁴⁴
Teoh K H, Christakis G T, Weisel R D - Accelerated myocardial metabolic recovery with terminal warm blood cardioplegia (hot shot). J Thorac Cardiovasc Surg 1986; 91: 888-95.

Endereço para correspondência:

Fernando Antônio Reis Filho

Av. Raja Gabaglía, 1002 - Gutierrez

Belo Horizonte, MG, Brasil. CEP: 30380-090

Tel. 337-5933

Datas de Publicação

Publicação nesta coleção
16 Dez 2010
Data do Fascículo
Dez 1996

This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License.

[1] ¹
Melrose D G, Dreyer B, Bentall H H, Baker J B E - Elective cardiac arrest. Lancet 1955; 2: 21-2.

[2] ²
Blanco G, Adam A, Fernandez A - A direct experimental approach to the aortic valve: II. Acute retroperfusion of coronary sinus. J Thorac Surg 1956; 32: 171.

[3] ³
Gott V L, Gonzales J L, Zuhdi M N - Retrograde perfusion of coronary sinus for direct vision aortic surgery. Surg Gynecol Obstet 1957; 104: 319.

[4] ⁴
Lillehey C N, De Wall R A, Gott V L, Varco R L - The direct vision correction of calcified aortic stenosis by means of a pump-oxygenator and retrograde coronary sinus perfusion. Dis Chest 1956; 30: 123.

[5] ⁵
Solorzano J, Taitelbaum G, Chiu R C - Retrograde coronary sinus perfusion for myocardial protection during cardiopulmonary bypass. Ann Thorac Surg 1978; 25: 201-8.

[6] ⁶
Menasché P, Kural S, Fauchet M et al. - Retrograde coronary sinus perfusion: a safe alternative for ensuring cardioplegic delivery in aortic valve surgery. Ann Thorac Surg 1982; 34: 647-58.

[7] ⁷
Menasché P & Pwinica A H - Retrograde coronary sinus perfusion. In: Roberts A J, ed. Myocardial protection during cardiac surgery. New York: Marcel Dekker, 1987: 251-62.

[8] ⁸
Shapira N, Lemole G M, Spagna P M, Bonner F J, Fernandez J, Morse D - Antegrade and retrograde infusion of cardioplegia: assessment by thermovision. Ann Thorac Surg 1987; 43: 92-7.

[9] ⁹
Lazar H L - Coronary sinus interventions during cardiac surgery. Ann Thorac Surg 1988; 46: 475-82.

[10] ¹⁰
Chitwood W R - Myocardial protection by retrograde cardioplegia: coronary sinus and right atrial methods. In: Cardiac surgery: state of art reviews, vol.2. Philadelphia: Hanley and Belfus, 1988: 197-218.

[11] ¹¹
Sutter F P, Goldman S M, Clancy M et al. - Continuous retrograde blood cardioplegia. Ann Thorac Surg 1991; 51: 136-7.

[12] ¹²
Bolling S F, Flaherty J T, Bulkley B H, Gott V L, Gradner T J - Improved myocardial preservation during global ischemia by continuous retrograde coronary sinus perfusion. J Thorac Cardiovasc Surg 1983; 86: 659-66.

[13] ¹³
Gundry S R & Hirsh M M - A comparison of retrograde versus antegrade cardioplegia in the presence of coronary artery obstruction. Ann Thorac Surg 1984; 38: 124-7.

[14] ¹⁴
Horneffer P J, Gott V L, Gardner T J - Retrograde coronary sinus perfusion prevents infarct extension during intraoperative global ischemic arrest. Ann Thorac Surg 1986; 42: 132-42.

[15] ¹⁵
Masuda M, Yonega K, Shiki K, Morita S, Kohno H, Tokunaga K - Myocardial protection in coronary occlusion by retrograde cardioplegic perfusion via the coronary sinus in dogs. J Thorac Cardiovasc Surg 1986; 92: 255-63.

[16] ¹⁶
Partington M T, Acar C, Buckberg G D, Julia P, Kofsky E R, Bugy H I - Studies of retrograde cardioplegia: I. Capillary blood flow distribution to myocardium supplied by open and occluded arteries. J Thorac Cardiovasc Surg 1989; 97: 605-12.

[17] ¹⁷
Haan C, Lazar H L, Bernard S, Rivers S, Zallnick J, Shemin R J - Superiority of retrograde cardioplegia after acute coronary occlusion. Ann Thorac Surg 1991; 51: 408-12.

[18] ¹⁸
Schaper j, Walter P, Scheld H, Hehrlein F - The effects of retrograde perfusion of cardioplegic solution in cardiac operations. J Thorac Surg 1985; 90: 882-7.

[19] ¹⁹
Snyder H E, Smithwick W, Wingard T, Agnew R C - Retrograde coronary sinus perfusion. Ann Thorac Surg 1988; 46: 389-90.

[20] ²⁰
Fiore A C, Naunheim K S, Kaiser G C et al. - Coronary sinus versus aortic root perfusion with blood cardioplegia in elective myocardial revascularization. Ann Thorac Surg 1989; 47: 684-8.

[21] ²¹
Lichtenstein S V, Ashe K A, Dalati H E, Cusimano R J, Panos A, Slutsky A S - Warm heart surgery. J Thorac Cardiovasc Surg 1991; 101: 269-74.

[22] ²²
Buckberg G D - Antegrade/retrograde blood cardioplegia to ensure cardioplegic distribution: operative techniques and objectives. J Card Surg 1989; 4: 216-38.

[23] ²³
Kalmbach T & Bhayana J N - Cardioplegia delivery by combined aortic root and coronary sinus perfusion. Ann Thorac Surg 1989; 47: 316-7.

[24] ²⁴
Drinkwater D C, Laks H, Buckberg G D - A new simplified method of optimizing cardioplegic delivery without righ heart isolation. J Thorac Cardiovasc Surg 1990; 100: 56-64.

[25] ²⁵
Drinkwater D C, Cushen C K, Laks H, Buckberg G D - The use of combined antegrade/retrograde infusion of blood cardioplegic solution in pediatric patients undergoing heart operations. J Thorac Cardiovasc Surg 1992; 104: 1349-55.

[26] ²⁶
Kennedy J W, Kaiser G C, Fisher L D et al. - Clinical and angiographic predictors of operative mortality from the Collaborative Study in Coronary Artery Surgery (CASS). Circulation 1981; 63: 793-802.

[27] ²⁷
Naunheim K S, Fiori A C, Wadley S S - The changing profile of the patient undergoing coronary artery bypass surgery. J Am Coll Cardiol 1988; 11: 494-8.

[28] ²⁸
Hearse D J, Braimbridge M V, Jynge P - Ischemia and reperfusion: the progression and prevention of tissue injury. In: Protection of the ischemic myocardium: cardioplegia. New York: Raven Press, 1981: 21.

[29] ²⁹
Roberts A J - Myocardial protection in cardiac surgery. New York: Marcel Dekker, 1987.

[30] ³⁰
Macmanus Q, Grunkemeier G, Lambert L, Dietl C, Starr A - Aortic valve replacement and aorta-coronary bypass surgery: results with perfusion of proximal and distal coronary arteries. J Thorac Cardiovasc Surg 1978; 75: 865-9.

[31] ³¹
Buckberg G D - A proposed "solution" to the cardioplegic controversy. J Thorac Cardiovasc Surg 1979; 77: 803-15.

[32] ³²
Chiu R C J, Blundell P E, Scott H J, Cain S - The importance of monitoring intramyocardial temperature during hypothermic myocardial protection. Ann Thorac Surg 1979; 28: 317-22.

[33] ³³
Oldham H N, Jones R H, Harris C C, Howe W R, Goodrich J k, Sabiston Jr. D C - Intraoperative relationships between regional myocardial distribution of bypass graft flow and the coronary collateral circulation. J Thorac Cardiovasc Surg 1979; 77: 32-8.

[34] ³⁴
Hilton C J, Teubl W, Acker M et al - Inadequate cardioplegic protection with obstructed coronary arteries. Ann Thorac Surg 1979; 28: 323-34.

[35] ³⁵
Fishman N H & Abouav J - Myocardial temperature differences as a guide to the order of coronary artery bypass anastomoses in high-risk patients. Am J Surg 1980; 140: 92-8.

[36] ³⁶
Ekroth R, Berggren H, Sudow G, Wojciechowski J, Zackrisson B F, Willian-Olsson G - Thermographic demonstration of uneven myocardial cooling in patients with coronary lesions. Ann Thorac Surg 1980; 29: 341-5.

[37] ³⁷
Daggett W M, Jacocks M A, Coleman W S, Jonhson R G, Lowenstein E, Vander Salm T J - Myocardial temperature mapping: improved intraoperative myocardial preservation. J Thorac Cardiovasc Surg 1981; 82: 883-8.

[38] ³⁸
Becker H, Vinten-Johansen J, Buckberg G D, Follette D M, Robertson J M - Critical importance of ensuring cardioplegic delivery with coronary stenosis. J Thorac Cardiovasc Surg 1981; 81: 507-15.

[39] ³⁹
Grodin C M, Helias J, Vonhe P R, Robert P - Influence of a critical coronary artery stenosis on myocardial protection through cold cardioplegia. J Thorac Cardiovasc Surg 1981; 82: 608-12.

[40] ⁴⁰
Landymore R W, Tice D, Trehan N, Spencer F - Importance of topical hypothermia to ensure uniform myocardial cooling during coronary artery bypass. J Thorac Cardiovasc Surg 1981; 82: 832-6.

[41] ⁴¹
Heineman F W, MacGregor D C, Wilson J G, Ninomiya J - Regional and transmural myocardial temperature distribuition in cold chemical cardioplegia. J Thorac Cardiovasc Surg 1981; 81: 851-9.

[42] ⁴²
Robertson J M, Buckberg G D, Viten-Johansen J, Leaf J D - Comparison of distribution beyond coronary stenosis of blood and asanguineous cardioplegic solutions. J Thorac Cardiovasc Surg 1983; 82: 80-6.

[43] ⁴³
Rosenkranz E R, Vinten-Johansen J, Buckberg G D, Okanoto F, Edward H, Bugyi H - Benefits of normothermic induction of blood cardioplegia in energy-depleted hearts, with maintenance of arrest by multidose cold blood cardioplegia infusions. J Thorac Cardiovasc Surg 1982; 84: 667-77.

[44] ⁴⁴
Teoh K H, Christakis G T, Weisel R D - Accelerated myocardial metabolic recovery with terminal warm blood cardioplegia (hot shot). J Thorac Cardiovasc Surg 1986; 91: 888-95.