Effect of Cardioplegic Infusion of Antegrade Aortic Root and Bypass Graft Combined With Passive Graft

Perfusion in On-Pump CABG

Tugrul Göncü1, Mustafa Günes1, Mustafa Sezen1, Hasan Ari2, Faruk Toktas1, Ahmet Demir1, Osman Tiryakioglu1, Hakan Vural1, Senol

Yavuz1, Ahmet Ozyazicioglu1

1Department of cardiovascular Surgery, Bursa Yuksek IhtisasEducation and Research Hospital, Bursa, Turkey

Introduction

• Coronary artery bypass grafting (CABG) performed withthe aid of cardioplegia and cardiopulmonary bypass (CPB) requires a period of cardiac arrest.

• During this time, myocardial ischemia may occur, whichis an important determinant of functional and clinicaloutcome [1]

• Both the duration of the period of aortic clamping and the duration of cardiopulmonary bypass have been consistently shown to be the main determinants of postoperative outcomes of cardiac surgery [2-4].

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• Antegrade cardioplegia remains the single mostwidespread mode of administration to protectthe myocardium during cardiac surgicalprocedures [5].

• However, in patients with severe coronary arterydisease, cardioplegia maldistribution can occurwith the use of antegrade cardioplegia alone [6-8]

• These potential problems may be overcome by direct delivery of cardioplegia via grafts.

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• In this study, our aim was to investigate the beneficial effects of intermittent antegrade aortic root and graft cardioplegic deliverycombined with early perfusion of the grafted ischemic myocardial segments with warm arterial blood during the construction of proximal graft anastomosis on myocardial protection and performance in on-pump CABG procedures.

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MATERIALS AND METHODS

• A prospective, randomized clinical trial was planned.

• Following the permission of the Institutional Review Board of our hospital, between June 2006 and October 2009, 96 patients undergoing on-pump CABG were randomly divided into two groups consisting of 48 patients each.

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• Group A (n=48) received antegrade cardioplegic infusion via the aortic root;

• Group B (n=48) received antegrade cardioplegic infusion via the aortic root supplemented with antegrade perfusion of vein or free arterial grafts after each distal anastomosis was completed. Additionally, graft perfusion with warm arterial blood was applied after the cross-clamp until the proximal anastomosis was completed.

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The use of a multiple perfusion set (MPS) in group B patients

•In this technique, the aortic perfusion branch of the MPS is kept clamped during the cross-clamp period, and each vein or free artery graft is perfused in an antegrade fashion following completion of distal anastomosis in addition to cardioplegia being administered from the aortic root.

After the cross-clamp is taken off, the clamp on the aortic branch is removed and early perfusion with warm arterial blood is initiated.

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• The groups were compared by clinical and biochemical markers of ischemic myocardial damage.

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RESULTS

Patients in each group were similar with respect to most of the preoperative characteristics

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At the end of cardiopulmonary bypass, most of the data were similar between the two groups. No statistically significant differences were noted between the mean number of distal anastomoses or mean aortic cross-clamp and partial occluding clamp times. However, the mean CPB time in group B was significantly lower than that of group A (82.9±13.4 min in group A vs. 75.1±16.5 min in group B, p=0.01).After declamping the ascending aorta, sinus rhythm returned spontaneously without electrical defibrillation in 21 patients (43.8%) from group A as compared with 41 (85.4%) from group B (p<0.001). Conversely, 27 patients (56.2%) from group A and 7 patients (14.6%) from group B needed defibrillation after aortic declamping. The need for defibrillation was significantly higher in group A (p<0.001).The number of patients who did not require any inotropic support was statistically higher in group B (p= 0.03). There was no significant difference between the two groups in regards to the number of patients requiring low or medium dose inotropic support. However, more patients who underwent antegrade aortic root cardioplegic delivery alone required a high dose of inotropic support (p= 0.02).

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After surgery, there were significant increases in the peak serum CK-MB and cTn-I levels in both groups, indicating myocardial injury (p=0.002 in group A and p=0.008 in group B). When compared to group A, group B showed lower peak levels of cTn-I and CK-MB at 12 hours (p=0.01 and p=0.02, respectively).

After surgery, there were significant increases in the peak serum CK-MB and cTn-I levels in both groups, indicating myocardial injury (p=0.002 in group A and p=0.008 in group B). When compared to group A, group B showed lower peak levels of cTn-I and CK-MB at 12 hours (p=0.01 and p=0.02, respectively).

After surgery, there were significant increases in the peak serum CK-MB and cTn-I levels in both groups, indicating myocardial injury (p=0.002 in group A and p=0.008 in group B). When compared to group A, group B showed lower peak levels of cTn-I and CK-MB at 12 hours (p=0.01 and p=0.02, respectively).

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• The peak serum cTn-I and CK-MB level differences were more significant inthe subgroup analysis at 12 hours. In the subgroup of severe right coronaryartery stenosis (>90%), CK-MB: p=0.007 and cTn-I: p=0.008 (Figures A and B),and in the subgroup of low left ventricular ejection fraction (30-40%), CK-MB:p=0.002 and cTnI: p=0.004 (Figures C and D).

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• In regards to the echocardiographic data taken on the sixth postoperative day, both types of myocardial protection techniques demonstrated minimal improvement in the left ventricle ejection fractions. Mean preoperative LVEF% values were: group A, 47.7±8.5; group B, 48.4±9.4 (p=0.64). Mean postoperative LVEF% values were: group A, 48.9±7.9; group B, 51.7±7.6 (p=0.08).

• The mean length of intensive care unit stay was: group A, 2.72±0.53 days vs. group B, 2.54±0.35 days (p=0.04); mean hospital stay was: group A, 7.58±1.4 days vs. group B 7.08±0.8 days (p=0.04).

• There were three hospital mortalities between 3-15 days postoperation: one (2.08%) in group A due to mesenteric infarction and two (4.16%) in group B due to generalized sepsis and multi-organ dysfunction.

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Discussion

• In the present study, we have applied a technique similar to the method Goldman et al. first described in 1987 [20].

• Our version of the technique facilitates antegrade selective cardioplegia perfusion by means of free grafts following each distal anastomosis in addition to antegrade cardioplegia administered from the aortic root in the beginning.

• This technique can also supply blood flow to the ischemic myocardium during construction of the proximal graft anastomosis, promoting early reperfusion and rapid recovery of grafted ischemic myocardial regions, which may decrease ischemia time.

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• Our findings are in accord with the suggestion that selective antegrade graft cardioplegia may lead to lower rates of myocardial injury by homogenous distribution of cardioplegia solution, especially in areas of critical coronary artery stenosis or complete coronary artery occlusion.

• In addition to this, our technique facilitates earlier warm blood perfusion of the grafts, and thus the ischemic myocardial areas, until the proximal anastomosis is performed and the cross-clamp is taken off.

• Together, these factors may lead to a lower rate of ischemia-reperfusion injury, earlier recovery from myocardial deterioration, and a minimized risk of post-ischemic myocardial dysfunction.

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CONCLUSION

• We believe that our technique may prove useful in lowering the mortality and morbidity rates following surgery in patients with multi-vessel coronary artery stenosis and poor ventricular function when compared with other myocardial preservation methods.

• Combined with our technique, retrograde cardioplegia may improve this preservation even more. However, we believe that further studies with a larger group of patients are needed to reach a definitive conclusion.

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