Experimental Evidence of Regional Myocardial Ischemia during Beating Heart Coronary Bypass: Prevention with Temporary Intraluminal Shunts

Authors

  • Sylvio M. A. Gandra
  • Luiz A. Rivetti

DOI:

https://doi.org/10.1532/hsf.869

Abstract

Background: Our center has been performing beating heart coronary artery bypass grafting with a temporary intraluminal shunt since 1983. Based on our clinical observations of more than 846 surgical cases, we believe that a temporary intraluminal shunt (TIS) greatly reduces the risk of the patient developing regional myocardial ischemia during clamping of the coronary artery. To seek evidence in support of our clinical observations, we evaluated the effects of coronary clamping with and without TIS in a porcine experimental model.

Methods: We compared 2 groups of healthy Landrace pigs that underwent the same period of coronary occlusion but differed only in whether a TIS was used. The shunt device was a straight flow-through silicone tube that has been described in detail in previous publications. Ischemic changes during the test period were detected via analysis of monophasic action potential (MAP) recordings. MAPs were recorded with the contact electrode technique, which has been shown to be specific for ischemia. In group I (no shunt) animals (n = 25), MAPs were monitored during a single 15-minute occlusion of the left anterior descending (LAD) coronary artery without any form of distal perfusion. In group II (shunted) animals (n = 15), MAPs were sampled over the same intervals after the LAD was snared and opened and the TIS was introduced within the first 2 minutes. Infarct analysis using biochemical end points (serum lactate dehydrogenase [LDH] and creatine phosphokinase-myocardial band [CPK-MB]) was performed with standard serologic assays.

Results: Confirming the presence of regional ischemia in group I (no shunt) were significant changes from baseline in measurements of mean action potential duration, upstroke velocity (dV/dt), and total MAP area (millivolts·milliseconds). The presence of ischemia in group I was also confirmed by significant elevations in serum LDH and CPK-MB levels. Furthermore, the use of lidocaine was greater in group I (no shunt) animals than in group II (shunted) animals because of the greater frequency of ventricular arrhythmias in group I (P = .001). Six animals (24%) in group I and no animals in group II developed ventricular fibrillation during the 15 minutes of occlusion (P = .046). Ischemic changes in the MAP were found only prior to shunt insertion in Group II animals, and the MAP then promptly returned to normal a few minutes after TIS flow was established. Statistical analysis revealed significant differences between group I and group II in MAP duration, dV/dt, total area, lidocaine requirements, incidence of ventricular fibrillation, and serum LDH levels.

Conclusions: There has been controversy about the relative effectiveness of temporary intraluminal shunting for reducing the risk of regional myocardial ischemia during beating heart coronary artery bypass grafting. At least in this porcine model, we could demonstrate a positive effect of shunting, which parallels our clinical experience using TIS in hundreds of patients for the past 2 decades. In the animal model, we demonstrated preservation of the MAP, as well as a reduction in both the incidence of ventricular arrhythmias and the serum levels of ischemic by-products, when temporary intraluminal shunting was used. It is our conclusion that intraluminal shunts do protect the vulnerable myocardium from regional ischemia during the period of temporary coronary occlusion necessary for construction of a bypass graft on the beating heart. Temporary intraluminal shunting is a cost-effective adjunct that can increase safety and reliability in off-pump coronary artery bypass grafting.

References

Buffolo E, Andrade JCS, Succi JE, et al. 1983. Revascularização direta do miocárdio sem circulação extracorpórea. Descrição da técnica e resultados iniciais. Arq Bras Cardiol 41:309-16.nBuffolo E, Andrade JCS, Succi JE, Leão LEV, Gallucci C. 1985. Direct myocardial revascularization without cardiopulmonary bypass. Thorac Cardiovasc Surg 33:26-9.nBuffolo E, Andrade JCS, Succi JE, et al. 1986. Revascularização diretado miocárdio sem circulação extracorpórea: estudo crítico dos resultadosem 391 pacientes. Rev Bras Circ Cardiovasc 1:32-8.nBuffolo E, Andrade JCS, Branco JNR, Aguiar LF, Ribeiro EE, Jatene AD. 1990. Myocardial revascularization without extracorporeal circulation: seven year experience in 593 cases. Eur J Cardiothorac Surg 4:504-8.nCarmeliet E. 1978. Cardiac transmembrane potentials and metabolism. Circ Res 42:577-87.nConnolly JF. The history of coronary artery surgery. 1978. J Thorac Cardiovasc Surg 76:733-44.nCorso PG. 1991. Cardiopulmonary bypass and coronary artery bypass graft. Are the risks necessary? Chest 100:298-9.nKolessov VI. 1967. Mammary artery-coronary artery anastomosis as method of treatment for angina pectoris. J Thorac Cardiovasc Surg 54:535-44.nLab MJ, Woollard KV. 1978. Monophasic action potential electrocardiograms and mechanical performance in normal and ischemic epicardial segments in the pig. Cardiovasc Res 13:555-65.nLab MJ, Woollard KV. 1980. Time course of changes in action potential duration and ejection shortening during regional transient ischemia of pig ventricle in situ. In: Baan J, Arntzenius AC, Yellin EL, editors. Cardiac dynamics. The Hague, Netherlands: Martinus Nijhoff. p 61-7.nLeiner AA. 1992. Potential de ação monofásico do músculo cardíaco: sistema para obtenção e avaliação experimental [dissertation]. São Paulo, Brazil: Faculdade de Medicina da Universidade de São Paulo.nLevites R, Banka VS, Helfant RH. 1975. Electrophysiologic effects of coronary occlusion and reperfusion: observations of refractoriness and ventricular automacity. Circulation 52:760-5.nLumb GD, Hardy LB. 1963. Collateral circulation and survival related to gradual occlusion of the right coronary artery in the pig. Circulation 27:717-21.nLuz PL, Barros LFM, Leite JJ, Pileggi F, Décourt LV. 1980. Effect of verapamil on regional coronary and myocardial perfusion during acute coronary occlusion. Am J Cardiol 45:269-75.nFranz MR. 1983. Long-term recording of monophasic action potential from human endocardium. Am J Cardiol 51:1629-34.nFranz MR, Flaherty JT, Platia EV, Bulkley BH, Weisfeld ML. 1984. Localisation of regional myocardial ischemia by recording of monophasic action potentials. Circulation 69:593-604.nFranz MR, Burkhoff D, Spurgeon H, Weisfeldt ML, Lakatt EG. 1986. In vitro validation of a new cardiac catheter technique recording of monophasic action potentials. Eur Heart J 7:34-41.nFranz MR. 1991. Method and theory of monophasic action potential recording. Prog Cardiovasc Dis 33:347-68.nHoffman BF, Suckling EE. 1954. Effect of heart rate on cardiac membrane potentials and unipolar electrogram. Am J Physiol 179:123-30.nJanse MJ, Kleber AG. 1981. Electrophysiological changes and ventricular arrhythmias in the early phase of regional myocardial ischemia. Circ Res 49:1069-81.nJanse MJ. 1986. Electrophysiological effects of myocardial ischemia: relationship with early ventricular arrhythmias. Eur Heart J 7:35-43.nMohabir R, Franz MR, Clusin WT. 1991. In vivo electrophysiological detection of myocardial ischemia through monophasic action potential recording. Prog Cardiovasc Dis 34:15-28.nMurray G, Porcheron R, Hilario J, Rosemblau W. 1954. Anastomosis of a systemic artery to the coronary. Can Med Assoc J 71:594-7.nNayler WG. 1981. The role of calcium in the ischemic myocardium. Am J Pathol 102:262-70.nNoll F, Bergmeyer HU. 1974. Methoden der enzymatischen Analyse. Tomo II. 3rd ed. Weinheim, Germany: Verlag Chemie, p 1521.nPfister AJ, Zaki MS, Garcia JM, et al. 1992. Coronary artery bypass without cardiopulmonary bypass. Ann Thorac Surg 54:1085-92.nPlatou ES, Steinnes K, Refsum H. 1984. A method for simultaneous epicardial monophasic action potential recordings from the dog heart in situ. Acta Pharmacol Toxicol 54:94-103.nRivetti LA, Gandra SMA. 1991. Revascularização cirúrgica do miocárdio sem auxílio de circulação extracorpórea comderivação interna temporária. Rev Soc Cardiol 2:65-71.nRivetti LA. 1992. Revascularização do miocárdio sem circulação extracorpórea com derivação intraluminal temporária [dissertation]. São Paulo,Brazil: Faculdade de Ciências Médicas da Santa Casa de São Paulo.nRivetti LA, Gandra SMA. 1997. Initial experience using an intraluminal shunt during revascularization of the beating heart. Ann Thorac Surg 63:1742-7.nRivetti LA, Gandra SMA. 1998. An intraluminal shunt for off-pump coronary artery bypass grafting: report of 501 cases and a review of the technique. Heart Surg Forum 1:30-6.nRussel DC, Smith HJ, Oliver MF. 1979. Transmembrane potential changes and ventricular fibrillation during repetitive myocardial ischemia in the dog. Br Hear J 42:88-96.nSabiston DC. 1974. The coronary circulation. Johns Hopkins Med J 134:314-29.nSmith FM. 1918. The ligation of coronary arteries with electrocardiographic study. Arch Intern Med 22:8-27.nSutton PM, Taggart P, Spear DW, Drake HF, Swanton RH, Emanuel RW. 1989. Monophasic action potential recording in response to graded hyperkalemia in dogs. Am J Physiol 256:H956-61.nTaggart P, Sutton P, Runnals M, et al. 1986. Use of monophasic action potential recording during routine coronary-artery bypass surgery as an index of localized myocardial ischaemia. Lancet 1:1462-5.nBenetti FJ, Naselli G, Beltrame RG, Rosenberg J. 1984. Cirurgia delinfarto agudo de miocardio sin circulación extracorporea ni parada cardiaca. Prensa Med Argent 71:555-8.nBenetti FJ. 1985. Direct coronary surgery with saphenous vein bypass without either cardiopulmonary bypass or cardiac arrest. J Cardiovasc Surg 26:217-22.nBenetti FJ, Naselli G, Wood M, Geffner L. 1991. Direct myocardial revascularization without extracorporeal circulation: experience in >700 patients. Chest 100:312-6.nBlair E. 1969. Significance of sampling sites in the study of myocardial metabolism in regional ischemia. J Thorac Cardiovasc Surg 38:271-8.nBlumgart HL, Gilligan DR, Schlesinger MJ. 1941. Experimental studies on effect of temporary occlusion of coronary arteries: production of myocardial infarction. Am Heart J 22:374-89.nBoyett MR, Jewell BR. 1978. A study of the factors responsible for rate-dependent shortening of the action potential in mammalian ventricular muscle. J Physiol 285:359-80.nDilly SG, Lab MJ. 1987. Changes in monophasic action potential duration during the first hour of regional ischemia on the anaesthetised pig. Cardiovasc Res 21:908-15.nDilly SG, Lab MJ. 1988. Electrophysiological alternans and restitution during acute regional ischaemia in myocardium of anaesthetized pigs. J Physiol 402:315-33.nDownar E, Janse MJ, Durrer D. 1977. The effects of acute coronary artery occlusion on subepicardial transmembrane potentials in the intact porcine heart. Circulation 56:217-24.nFanning WJ, Kakos GS, Williams TE Jr. 1993. Reoperative coronary artery bypass grafting without cardiopulmonary bypass. Ann Thorac Surg 55:486-9.nFedor J, Mcintosh D, Rembert JC, Greenfield JC Jr. 1978. Coronary and transmural myocardial blood flow response in awake domestic pigs. Am J Physiol 235:435-44.nFozzard HA, Makielski JC. 1985. The electrophysiology of acute myocardial ischemia. Ann Rev Med 36:275-84.nFranz M, Schöttler M, Schaeffer J, Seed WA. 1980. Simultaneous recording of monophasic action potentials and contractive force from the human heart. Klin Wochenschr 58:1357-9.nTaggart P, Sutton PMI, Spear DW, Drake HF, Swanton RH, Emanuel RW. 1988a. Simultaneous endocardial and epicardial monophasic action potential recordings during brief periods of coronary artery ligation in the dog: influence of adrenaline, beta blockade and alpha blockade. Cardiovasc Res 22:900-9.nTaggart P, Sutton PMI, Treasure T, et al. 1988b. Monophasic action potentials at discontinuation of cardiopulmonary bypass: evidence for contraction-excitation feedback in man. Circulation 77:1266-75.nThal A, Perry JF Jr, Miller FA, Wangensteen OH. 1956. Direct suture anastomosis of the coronary arteries in the dog. Surgery 40:1023-9.nTrautwein W, Dudel J. 1956. Aktionspotential und Kontraction des Herzmuskels in Sauerstoffmangel. Pflügers Arch 236:23-32.nWürzburg U. 1981. Rapid and quantitative determination of creatine kinase-MB activity in serum using immunological inhibition of creatine kinase M subunit activity. In: Barnett RN, Goetz WA, editors. CK-MB methods and clinical significance. Proceedings of the CK-MB Symposium; 1981 Mar 25-27; Philadelphia, PA. Darmstadt, Germany: GIT-Verlag, p 11-22.nYabuki S, Blanco G, Imbriglia JE, Bentivoglio L, Bailey CP. 1959. Time studies of acute, reversible, coronary occlusion in dogs. J Thorac Cardiovasc Surg 38:40-5.nAbe S, Nagamoto Y, Fukuchi Y, Hayakawa T, Kuroiwa A. 1989. Relationship of alternans of monophasic action potential and conduction delay inside in the ischemic border zone to serious ventricular arrhythmia during acute myocardial ischemia in dogs. Am Heart J 117:1223-33.nBazett HC. 1920. An analysis of the time-relations of electrocardiograms. Heart J 7:353-70.n

Published

2005-02-02

How to Cite

Gandra, S. M. A., & Rivetti, L. A. (2005). Experimental Evidence of Regional Myocardial Ischemia during Beating Heart Coronary Bypass: Prevention with Temporary Intraluminal Shunts. The Heart Surgery Forum, 6(1), 10-18. https://doi.org/10.1532/hsf.869

Issue

Section

Articles