Mohammed Akhter

Conversion to Cardiopulmonary Bypass in Off-pump Coronary Artery Bypass Grafting: Its Effect on Outcome

Abstract The surgical outcome of patients requiring conversion to cardiopulmonary bypass (CPB) during myocardial revascularization using the less invasive surgical approach (LISA) was assessed. The LISA was recently introduced as a technique for complete myocardial revascularization without CPB. It combines avoidance of CPB with the versatility of a median sternotomy for access to all coronary vessels. We have previously demonstrated reduced risk‐adjusted mortality and complications in off‐CPB coronary artery bypass grafting (CABG) using LISA compared to standard myocardial revascularization. From January to December 1997, 1210 patients underwent isolated CABG at our institution. Of these patients, 832 (63%) were scheduled as on‐CPB cases and 378 (37%) as off‐CPB. Of the off‐CPB patients, 48 were converted to CPB. Team A surgeons used LISA as their primary strategy for CABG whereas team B surgeons used off‐CPB CABG in selected patients. Conversions were divided in three classes: Class I patients were converted when the surgeon considered complete revascularization impossible off‐CPB; Class II patients were converted due to hemodynamic instability during the procedure; and Class III patients were converted due to graft malfunction, determined by flow measurements or clinical evidence. There were four deaths. All had perioperative infarctions and required intra‐aortic balloon pump (IABP). Conversion to CPB occurred in up to 25% of patients scheduled for off‐CPB CABG. When off‐CPB cases are done using the comprehensive LISA technique and modern technology, conversion rates may be reduced to 11%. Conversion is in general well tolerated except when it is instituted for graft malfunction combined with hemodynamic instability or collapse.

Pitfalls of undetected patent foramen ovale in off-pump cases

We describe pitfalls of a hitherto undetected patent foramen ovale during the conduct of an off-bypass coronary revascularization. Manipulation of the heart resulted in right-to-left shunt and severe desaturation requiring institution of cardiopulmonary bypass to close the patent foramen ovale and complete the revascularization.

Reoperations with the Right Gastroepiploic Artery without Cardiopulmonary Bypass

Abstract The right gastroepiploic artery (RGEA) has been utilized as the bypass conduit on the inferior surface of the heart with a minimally invasive approach. Fourteen patients had reoperative coronary bypass surgery for severely symptomatic single‐vessel disease of the right coronary artery. All surgeries were performed since May 1996. A small mid‐line incision including splitting of the lower sternum gave excellent exposure. The inferior surface of the heart was dissected to expose and stabilize the target vessel. The heart rate was controlled with a diltiazem drip. Cardiopulmonary bypass was not necessary in any case. The right coronary artery was bypassed in three patients, the posterior descending artery branch in ten patients, and the terminal circumflex of the left coronary artery in one. After grafting, patency of the anastomosis was demonstrated by Doppler echocardiogram. Two patients had left anterior descending artery (LAD) grafts with LIMA (left mammary artery) and RGEA grafts performed simultaneously with two port access incisions. No patient had perioperative mortality or complications. No patient had recurrent angina. Doppler color echocardiographic imaging studies before discharge confirmed patency of the graft in 13 of 14 cases. In one case, the gastroepiploic artery could not be visualized. Angiographic visualization was positive in seven cases; seven patients were not studied yet. The gastroepiploic artery is an excellent conduit for vascularization of the inferior aspect of the heart. The operation can be done with a minimally invasive technique and without the use of cardiopulmonary bypass. This approach seems especially applicable in selective reoperative cases.

Limited Access Left Thoracotomy for Reoperative Coronary Artery Disease: On or Off Pump

Abstract  Between 1971 and 1988 left thoracotomy was performed on pump for selected reoperations. Since 1993, 92 patients were operated on with a limited approach and an increased number of cases were done off pump (70 patients). The purpose of this paper is to describe the transition of our operative techniques from on pump to off pump for reoperative coronary patients. From 1995 to 1999, 22 patients (Group 1) were operated on pump and 70 patients (Group II) off pump; 86 of 92 (93.5%) had reoperations. The demographic data were similar in these two groups regarding age, gender, ejection fraction, and total number of grafts performed. In this study 92 patients had a crude mortality of 4.3%. Limited access thoractomy provides safer reoperation than previously (1971–1988) with an improved on or off pump (4.5% vs. 4.3%) mortality, compared to the on pump mortality of 10% between 1971–1988. Off‐pump operations are performed with increasing frequency and with the same risk and less postoperative complications.

Minimally invasive coronary artery bypass grafting using the right gastroepiploic artery without pump

OBJECTIVE To explore the feasibility to operate on the right coronary artery and its branches utilizing the right gastroepiploic artery (RGEA) without cardiopulmonary bypass (CPB). All cases were performed since May 1996. METHODS A small mid-line incision including splitting of the lower sternum gave excellent exposure. The inferior surface of the heart was dissected to expose and stabilize the target vessel. The heart rate was controlled with a Diltiazem drip. CPB was not necessary in any case. The right coronary artery was bypassed in four patients, the posterior descending artery branch in five patients and the terminal circumflex of the left coronary artery in one patient. After grafting, patency of the anastomosis was demonstrated by Doppler echocardiogram. RESULTS No patient had perioperative mortality or complications. No patient had recurrent angina. Color Doppler echocardiographic imaging studies before discharge confirmed patency of the graft in eight of ten cases. In two cases, the gastroepiploic artery could not be visualized. Angiographic visualization was positive in four out of five cases. CONCLUSIONS The gastroepiploic artery is an excellent conduit for vascularization of the inferior aspect of the heart. The operation can be done using a minimally invasive technique and without the use of cardiopulmonary bypass. This approach seems especially applicable in selective reoperative cases.

Pulmonary reperfusion injury : A comparison of bubble and membrane oxygenators

Twenty cases of single valve replacement or atrial septal defect repair who underwent elective corrective surgery using either membrane (Capiox E) oxygenator (n=10) or bubble (Bentley 10™) oxygenator (n=10) were studied for the activation of cellular and humoral elements in blood. The bubble oxygenator was found to have more damaging effect of platelet sequestration and pulmonary sequestration of leucocytes. The C3c and’ c4 levels were found to be equally decreased in both groups. Both groups however showed no significant pneumocyte changes and there was no adverse effect on the postoperative clinical outcome in both groups.

Emergency aorto-coronary bypass grafting following complications of coronary angioplasty

Acute myocardial ischaemia during percutaneous transluminal coronary angioplasty (PTCA) and allied procedures often necessitates emergency coronary artery bypass grafting (CABG). Between July 1987 and December 1993, a total of 1221 patients underwent PTCA for occlusive coronary artery disease. Twentytwo (1.8%) of them required emergency CABG for various complications. The most common complications leading to emergency CABG were intimal dissection and acute occlusion. Sixteen (72.7%) of these 22 patients were haemodynamlcally unstable when received in the operation suite. Seven of them were on percutaneousfemorofemoral cadiopulmonary bypass support, three on external cardiac massage and six supported with inotropes. The remaining six patients were haemodynamically stable. There were eight (36.3%) deaths, all in the haemodynamically unstable subset of patients.This study suggests that for better outcome from emergency CABG following complications of angioplasty, patient needs to be referred for surgery early while haemodynamics are still stable. Persistence with nonsurgical caiheter manoeuvres to treat ischaemia following an angioplasty complication results in inordinate delay leading to haemodynamic instability, the latter predicting a poor prognosis following emergency CABG.

Hypotension after the release of aortic cross clamp in patients undergoing open heart surgery

One hundred consecutive adult patients under-going various elective open heart surgical procedures were included in this prospective study. An indwelling radial arterial cannula was used to measure mean arterial pressure (MAP). Systemic vascular resistance (SVR) during bypass was calculated using the formula SVR=MAP×80/pump flow dynes-sec-cm−5. Patients in whom vasodilators were used during cardiopulmonary bypass were excluded. Measurements were made just before the release of aortic cross clamp when the pump flows were normal; and 1,3,5 and 10 minutes following the cross clamp release. There were 60 males and 40 females with a mean age of 29.4±13.9 years and mean weight of 46±13 Kg. The MAP fell from 65±14 to 47±15 mm Hg (p<0.00001) and the SVR fell from 1699±511 to 1163±365 dynes-sec-cm−5 (p<0.00001) one minute after the release of aortic cross clamp. There was some recovery during the subsequent period, but the change continued to remain statistically significant upto 10 minutes after the release of aortic cross clamp. MAP and SVR decreased in all except 9 and 3 patients respectively at 1 minute. The mean temperature at the time of release of aortic cross clamp was 33.7±2.7°C. There was a poor correlation between the temperature and duration of bypass and extent of decrease in MAP and/or SVR. We conclude that there is a significant decrease in MAP (27%) and SVR (31%) after the release of aortic cross clamp and it persists for 10 minutes.