Active distal coronary perfusion to prevent regional myocardial ischemia in off-pump coronary artery bypass grafting.

Regional myocardial ischemia during anastomosis in off-pump coronary artery bypass (OPCAB) can occasionally cause hemodynamic instability. To prevent regional myocardial ischemia and stabilize the hemodynamics during the procedure, perfusion of the distal coronary artery to the anastomotic site is necessary as the only reliable method. We have applied an active coronary perfusion method using a servo-controlled pump in selected patients in place of conventional passive perfusion methods (intraluminal shunt and external shunt). We present a case in which the active perfusion method proved useful in avoiding regional myocardial ischemia. A 74-year-old male patient with triple-vessel coronary disease underwent OPCAB for unstable angina. During revascularization of the main right coronary artery, the hemodynamics collapsed due to regional myocardial ischemia. As soon as the distal coronary artery was perfused at a high flow rate around 80 ml/min, the hemodynamics stabilized and the operation was completed successfully. This active coronary perfusion method in OPCAB is particularly useful in cases in which regional myocardial ischemia cause hemodynamic instability.     

非停跳冠脉搭桥术中病人心脏形态和功能的变化

目的观察非停跳冠脉搭桥术（OPCAB）中病人心脏形态和功能的变化。方法择期行OPCAB病人30例，ASAll或Ⅲ级。麻醉诱导后气管插管，经右侧颈内静脉放置CCO／SVO，／CEDV导管，连续监测血液动力学参数，经口放人多平面经食管彩色超声诊断仪探头，监测食管超声心动图（TEE）参数。分别于打开心包时（基础值）、前降支（LAD）搭桥、回旋支（LCX）搭桥、右冠状动脉（RCA）搭桥、吻合完毕时测定TEE参数及血液动力学参数。结果与基础值比较，LAD搭桥时二尖瓣血流E波减速时间（DL）缩短，经过二尖瓣口的左心流量（Q；）降低，MAP、HR下降，CVP升高；LCX搭桥时左心室舒张末直径（LVEDD）、右心室舒张末直径（RVEDD）、三尖瓣环直径（TVD）、射血分数（EF）、Q，、经过中尖瓣口的右心流量（Q2）、左心室流出道舒张变化率[（DDL—SDL）／DDL]、三尖瓣血流E／A比值（E2／A2）、TVD降低，二尖瓣血流E／A比值（E1／A1）升高，DL、三尖瓣血流E波减速时间（DT2）缩短，HR、MAP、每搏量（sV）、混合静脉血氧饱和度（蹄01）、右心室舒张末容积（RVEDV）、右心室收缩末容积（RVESV）、右心室射血分数（RVEF）、右心室舒经末容积指数（RVEDVI）降低，CVP升高；RCA搭桥时LVEDD、LVESD、二尖瓣环直径、Q，、E2／A2、HR、MAP、平均肺动脉压、SV、SvO2、RVEVD、RVESV、RVEF、RVEDVI降低，CVP升高，DT1缩短，右心室流出道舒张直径（RVOTDD）、右心室流出道收缩直径（RVOTSD）增加（P＜0．05）；吻合完毕时各指标恢复到基础值水平（P＞0．05）。心脏形态学表明LAD、RCA搭桥时以左心室直接受压为主，LCX搭桥时以右心室受压为主。结论在OPCAB中LAD、LCX、RCA搭桥时左右心室同时受压，但左右心室受压的程度随着搭桥血管、心脏位置不同而不同；心功能呈一过性的损害，在完成血管搭桥后均能恢复。     

Nonocclusive mesenteric ischemia after off-pump coronary artery bypass surgery: a word of caution

We present a series of five cases of off-pump coronary artery bypass surgery complicated with fatal nonocclusive mesenteric ischemia. We review a total of 489 patients aged 65 and older (mean age 74.9 +/- 3.2 years) who underwent off-pump coronary artery bypass surgery. The diagnosis of nonocclusive mesenteric ischemia was confirmed by computed tomography-angiography and/or selective angiography of the superior mesenteric artery, or intraoperatively. Three patients underwent laparotomy with bowel resection. In two cases, resection of bowel was not feasible. Of the possible predisposing factors, we found that four of the patients (two preoperative and two perioperative) had received epinephrine and two had an intra-aortic balloon counter pulsation due to acute myocardial infarction and cardiogenic shock. All patients were over 65 years of age, and all had acute anterior wall myocardial infarction and hemodynamic instability or post-myocardial infarction unstable angina. Nonocclusive mesenteric ischemia is a difficult clinical entity to recognize, has no clear-cut effective management, has a poor prognosis as a result of low cardiac output, and can be aggravated by off-pump coronary artery bypass grafting.     

Perioperative coronary artery spasm in off-pump coronary artery bypass grafting and its possible relation with perioperative hypomagnesemia.

PURPOSE: We experienced 3 cases of serious perioperative coronary artery spasm in off-pump coronary artery bypass grafting (OPCAB). In consideration of the causes, we directed our attention to hypomagnesemia, one of the triggers of coronary artery spasm. This study was performed to confirm the tendency to hypomagnesemia in OPCAB. METHODS: First, we report 3 patients having severe coronary artery spasm immediately after OPCAB with consideration of the causes. Second, serial magnesium (Mg) value (xylidyl blue method, normal 1.9-3.1 mg/dl) was measured in 45 consecutive patients with OPCAB between April and October 2002, 1) before starting the operation, and 2) after the patient's entrance into the intensive care unit. RESULTS: Preoperative and postoperative values of Mg (mg/dl) were 2.1+/-0.3, 1.7+/-0.3, respectively (p < 0.01). Postoperative incidence of hypomagnesemia was as high as 89% of the patients (40 out of 45 patients). In this study and thereafter, we corrected hypomagnesemia with magnesium sulfate during and after OPCAB, and no perioperative coronary artery spasm occurred. CONCLUSION: Hypomagnesemia, one of the triggers of coronary artery spasm, is very common in OPCAB. We strongly recommend the correction of hypomagnesemia during and after OPCAB for the prevention of perioperative coronary artery spasm.     

A simple method for heart stabilization during off-pump multi-vessel coronary artery bypass grafting: surgical technique and short term results.

Minimally invasive cardiac surgery regroups several technical options including small incision, video-assisted surgery and beating heart surgery but mechanical stabilization for off-pump multi-vessel coronary artery bypass grafting (CABG), remains a problem. We developed a simple method of stabilization with a fenestrated polytetrafluroethylene patch. Four sutures were passed deeply into the myocardium surrounding the anastomotic site. The sutures were then passed through the patch. Gentle traction on tied sutures, allowed immobilization and exposure in the selected area. This method which was carried in 95 patients, provides good stabilization for performing off-pump multi-vessel CABG in all cardiac territories.     

Robotically assisted atraumatic coronary artery bypass: a feasible option for off-pump coronary surgery

This retrospective study of the largest single center experience (100 patients) with off-pump robotically assisted coronary procedures in the United Kingdom (April 2002–June 2008) aimed to rationalize patient selection, describe the technique, and determine the learning curve, technical feasibility and operative outcome of robotically assisted Atraumatic Coronary Artery Bypass (ACAB). Selected patients underwent either a robotic Totally Endoscopic Coronary Artery Bypass (12) or robotically assisted ACAB (88) using a standard Da Vinci robot with three arms. A fifth of all cases had percutaneous interventions as part of a hybrid strategy. The majority of patients were overweight men. After one hundred robotic coronary procedures, this operation is now performed as part of a routine theatre list. The mean operative and total procedure times for robotically assisted atraumatic procedures were 157 and 238 min, respectively. These measurements were significantly less in the atraumatic than the totally endoscopic group with a 34.3 and 20.6% reduction, respectively (P < 0.001; equal variance not assumed). The procedural learning curve was short and independent from internal thoracic artery harvesting. We have proven conclusively that robotically assisted ACAB is feasible, more so than the totally endoscopic procedure in this particular setting. Even in the absence of an ideal stabilizer device, this procedure causes minimal disruption to the daily operating room schedule. We have also proven that body mass index is a weak predictor of the ease of robotic internal thoracic artery harvesting and should not affect patient selection.     

Hemodynamic changes during displacement of the beating heart using epicardial stabilization for off-pump coronary artery bypass graft surgery

OBJECTIVE: To evaluate the hemodynamic alterations during off-pump coronary artery bypass graft surgery to determine the degree of impairment caused and the techniques to rectify them. DESIGN: Prospective, observational cohort study performed from January 2000 through September 2000. PARTICIPANTS: Patients (n = 500) with coronary artery disease undergoing multivessel off-pump coronary artery bypass graft surgery using the Octopus tissue stabilizer (Medtronic, Inc, Minneapolis, MN). Unstable patients with ongoing ischemia were excluded from the study. INTERVENTIONS: All patients were monitored with radial artery and pulmonary artery catheters and continuous transesophageal echocardiography monitoring with a multiplane transducer. The perioperative requirement of an intracoronary shunt, inotropes, or an intra-aortic balloon pump was noted. The effect of the Trendelenburg position and fluids on hemodynamics was observed. The need for defibrillation and institution of emergency cardiopulmonary bypass were major endpoints to determine the inability of the patient to tolerate displacement of the heart. MEASUREMENTS AND MAIN RESULTS: Mean patient age was 59.3 +/- 11.6 years. There were 204 (40%) patients in the high-risk category; 54 (10.8%) patients had left ventricular ejection fraction <25%. The mean number of grafts was 2.7 +/- 0.8. Vertical displacement of the heart to access the lateral and inferior walls decreased the mean arterial pressure by 18 +/- 4% (p < 0.01), with a concomitant increase in central venous pressure of 66 +/- 18% (p < 0.001). The stroke volume and the cardiac index were reduced by 35.7 +/- 11% (p < 0.001) and 45 +/- 13% (p < 0.001). On transesophageal echocardiography, there was development of new regional wall motion abnormalities in 59.2% and a decrease in global left ventricular functions in 61.2%. The use of inotropes was highest during anastomosis on the posterior wall-78.4% compared with 21.9% for the anterior wall. An intra-aortic balloon pump was used in 55 (11.2%) patients, and 7 (0.71 %) patients had to be put on emergency CPB. The in-hospital mortality was 1.2%. CONCLUSION: Most patients had hemodynamic changes easily correctable by fluids and inotropes. Monitoring of left ventricular and right ventricular function by transesophageal echocardiography enhances safety of the procedure and is recommended. The use of the Octopus II tissue stabilizer proved to be a safe and versatile means to stabilize the heart during off-pump coronary artery bypass procedures, especially in high-risk patients.     

On-pump versus off-pump coronary artery bypass: independent risk factors and off-pump graft patency.

OBJECTIVE: Current knowledge on off-pump coronary artery bypass (OPCAB) generally stems from single surgeons' experience or from series where OPCABs constituted a minor fraction of coronary operations. The present center decided to venture as far into OPCAB as possible during 1999. The present series thus represents the average surgeon's experience. METHODS: During 1999, 533 patients underwent coronary artery bypass grafting using cardiopulmonary bypass (CPB) in 368 and OPCAB in 165 including the circumflex artery (CX) area in 91. Coronary arteriography was performed before discharge in the first 103 OPCAB patients. RESULTS: The CPB and OPCAB groups differed as regards left ventricular ejection fraction (53+/-13 versus 57+/-11, P < 0.0001) and frequency of triple-vessel or left main stem disease (84 versus 32%, P < 0.0001) but were comparable as regards diabetes (12%), prior myocardial infarct (57%), unstable angina (21%), and previous heart surgery (3%). Using multivariate analyses, 30-day mortality (1.3%), P-creatine kinase myocardial band (CKMB) > 80 microg/l (11.1%), re-sternotomy for bleeding (4.5%) or dehiscense (1.7%), transitory cerebral ischemia and stroke (1.7%), supraventricular tachycardia (27.4%), and hospital stay (mean 8 days) were unrelated to off- versus on-pump surgery as well as to OPCAB in triple-vessel disease. CX branches < or = 1mm, > or = 5 distal anastomoses, prior heart surgery, right coronary artery (RCA) branches < or = 1.5mm, 8-21 days old myocardial infarct, female gender, and preoperative acute arrhythmia (among others) were identified as independent risk factors for mortality or increased CKMB in all 533 patients. The latter five risk factors were reproduced in the OPCAB group isolated. The patency in the 103 OPCABs was 95.3, 91.8, and 85.3% in the left anterior descending artery (LAD), CX, and RCA, respectively. Patency was inversely related to diameter of the grafted vessel in the LAD and CX areas, unlike the RCA area. CONCLUSIONS: The results after beating heart surgery were good also in patients with triple-vessel disease, but specific gains relative to on-pump surgery could not be shown. The independent risk factors in the OPCAB group may indicate relative contraindications for OPCAB grafting.     

Postoperative atrial fibrillation: a comparison of off-pump coronary artery bypass surgery and conventional coronary artery bypass graft surgery

OBJECTIVE: To compare the incidence and pattern of onset of postoperative atrial fibrillation (AF) in patients undergoing coronary artery bypass graft (CABG) surgery with and without cardiopulmonary bypass (CPB). DESIGN: Retrospective, cohort-controlled study. SETTING: University hospital and tertiary referral center. PARTICIPANTS: A group of 108 consecutive patients who underwent primary off-pump coronary artery bypass (OP-CAB) surgery and a control group of 100 patients who underwent CABG surgery with CPB. All patients underwent surgery between January and September 1999. INTERVENTIONS: Patients in the OP-CAB surgery group were operated on by either of 2 surgeons. The CABG surgery group was drawn from the general pool of patients operated on by 1 of 10 surgeons. All patients underwent median sternotomy and received standard anesthesia and intensive care unit management for this institution. MEASUREMENTS AND MAIN RESULTS: Data from 99 OP-CAB surgery patients (data incomplete in 9 patients) were compared with data from 100 CABG surgery patients. General demographics were similar except the CABG surgery group received a higher mean number of distal anastomoses (3.3 v 3.0; p = 0.028) The incidence of AF was similar in both groups (OP-CAB surgery, 25% v CABG surgery, 18%; p = 0.228). The peak incidence of AF was postoperative day 2 in both groups. The median hospital length of stay was increased in patients developing AF. CONCLUSION: Avoiding CPB does not seem to reduce the incidence of postoperative AF in CABG surgery. The similar time distribution of onset of AF in OP-CAB surgery patients and CABG surgery patients may point toward a common cause.     

Arrhythmias in off-pump coronary artery bypass grafting and the antiarrhythmic effect of regional ischemic preconditioning

OBJECTIVE: The authors sought to establish whether regional ischemic preconditioning (IP) reduces ischemic reperfusion arrhythmias in patients who undergo off-pump coronary artery bypass grafting (OPCAB). DESIGN: A controlled, randomized, prospective study. SETTING: A university hospital. PARTICIPANTS: Thirty-two patients with left anterior descending coronary artery (LAD) or 2-vessel heart disease (including LAD) who were to undergo OPCAB were randomized into an IP and a control group. INTERVENTIONS: IP was induced by occluding the LAD twice for a 2-minute period followed by 3-minute LAD reperfusion before bypass grafting of the first coronary vessel. MEASUREMENTS AND MAIN RESULTS: Twenty-four-hour electrocardiography was recorded from the preoperative day to the second postoperative day. The heart rate (HR) was significantly elevated after surgery. Supraventricular extrasystole (SVES) events were similar before and after surgery. The incidence of patients with ventricular extrasystole (VES), supraventricular tachycardia (SVT), atrial fibrillation (AF), and ventricular tachycardia (VT) was significantly increased after the operation. Ventricular arrhythmias occurred mostly during anastomosis and the early reperfusion period and recovered 2 hours after reperfusion. Supraventricular tachyarrhythmias were mostly encountered 24 hours after reperfusion. IP significantly suppressed HR elevation, SVT, and VT after surgery. SVES, VES, and AF episodes were similar between the groups. CONCLUSIONS: Arrhythmia was a common phenomenon during and after an OPCAB procedure. The present IP protocol significantly suppressed HR elevation, the episodes of SVT, and the incidence of VT after surgery.     

Coronary perfusion methods during off-pump coronary artery bypass: results of a randomized clinical trial

BACKGROUND: Several techniques are being used to perform off-pump coronary artery bypass (OPCAB) grafting. This three-armed clinical trial was performed to determine whether one OPCAB method of coronary perfusion was superior over the others with respect to myocardial protection and performance. METHODS: Over the course of 11 months, 151 consecutive unselected patients underwent elective first-time OPCAB grafting by sternotomy performed by a single surgeon. Patients were prospectively randomized to receive one of three OPCAB coronary perfusion treatments: (1) no coronary perfusion (NCP), ie, OPCAB using no coronary perfusion during the distal anastomosis or graft perfusion after the distal anastomosis until all the proximal anastomoses were completed; (2) passive coronary perfusion (PCP), providing distal coronary perfusion during the anastomosis and immediate graft perfusion after the distal anastomosis by means of a passive cannula from the aorta; or (3) active coronary perfusion (ACP), providing assisted distal coronary perfusion and graft perfusion by means of an in-line pump (perfusion-assisted direct coronary artery bypass. Hemodynamic and biochemical data were recorded to disc continuously throughout the operation and postoperatively. RESULTS: With no statistically significant differences in the three treatment groups with respect to patient age, left ventricular systolic or diastolic function, and extent and distribution of coronary disease or grafts performed, cardiac performance postoperatively was superior in the active coronary perfusion group compared to the groups receiving either passive coronary perfusion or no coronary perfusion (p < 0.001). In addition, troponin I levels were lower in the coronary perfusion groups (PCP and ACP) (p = 0.023). CONCLUSIONS: Providing active coronary perfusion during the anastomosis and after each distal anastomosis by using an in-line pump resulted in superior myocardial protection and performance during OPCAB surgery when compared to either no coronary perfusion or passive coronary perfusion.     

Flow simulation of the intracoronary shunt tube for off-pump coronary artery bypass.

INTRODUCTION: To simulate blood flow provided by the intracoronary shunt tube, and to clarify whether this method is actually suitable for Off-pump coronary artery bypass (OPCAB), we investigated the efficacy of the intracoronary shunt tube in a theoretical model on the basis of fluid dynamics. METHODS: Fluid dynamics analysis was performed to simulate flow decrease after attachment on an intracoronary shunt model. RESULTS: The flow ratio in the case of turbulent flow is in proportion to the ratio of the inner diameter to the third power, and that in the case of laminar flow is in proportion to the ratio of the inner diameter to the sixth power. When this analysis is applied to commercial shunt tubes, coronary flow was estimated as approximately 2-14% of pre-attachment flow in turbulent flow, and only less than 0.1% in laminar flow. CONCLUSIONS: This result suggests that use of intracoronary shunt tubes in OPCAB may rarely contribute to maintenance of coronary flow, and they should be used carefully, especially in a jeopardized coronary artery.     

Endotoxemia in coronary artery bypass surgery: a comparison of the off-pump technique and conventional cardiopulmonary bypass

OBJECTIVES: The endotoxemia associated with cardiac surgery is thought to be dominantly influenced by the use of cardiopulmonary bypass. The objectives of this study were to assess the relative contribution of cardiopulmonary bypass on endotoxemia apart from cardiac surgical access and to improve our understanding of the potential benefits of off-pump procedures. METHODS: Thirty patients undergoing coronary artery bypass grafting were followed up prospectively. The patients were divided into 2 equal groups: those who underwent bypass grafting through a sternotomy incision without cardiopulmonary bypass (off-pump group) and those who underwent bypass grafting through a sternotomy incision with cardiopulmonary bypass (CPB group). Blood sampling for endotoxin, lactate, and cardiac index measurements were performed during the following time points: (1) after sternotomy; (2) during the coronary occlusion period in the off-pump group and during aortic clamping in the CPB group; (3) after removal of the coronary occlusion sutures in the off-pump group and after removal of the aortic clamp in the CPB group; (4) 30 minutes after the completion of all distal anastomoses in the off-pump group and immediately after weaning from cardiopulmonary bypass in the CPB group; (5) 1 hour postoperatively; and (6) 12 hours postoperatively. RESULTS: Endotoxin and lactate levels were significantly (P <.05) lower in the off-pump group at all sampling time points, except after sternotomy. CONCLUSIONS: In conclusion, this study has shown that endotoxemia during coronary artery bypass surgery seems mainly to be associated with cardiopulmonary bypass procedure. The relatively lower endotoxin levels observed in off-pump surgery might contribute to improved postoperative recovery.