Off-pump revascularization of the circumflex artery: technical aspect and short-term results

Iatrogenic Aortic Dissection Associated With Cardiac Surgery: A Narrative Review

Iatrogenic aortic dissection (iAD) is a relatively rare but a life-threatening complication associated with cardiac surgery. All members of the team caring for cardiac surgical patients (surgeons, perfusionists, and anesthesiologists) must be familiar with this complication to minimize its incidence and improve outcome. The present narrative review focuses on iAD occurring intraoperatively and during the early postoperative period (within 1 month) of cardiac surgery. The review also addresses iAD that occurs late (beyond 1 month) after cardiac surgery and iAD associated with other procedures. iAD occurs in about 0.06% of cases when the ascending aorta is the site of arterial cannulation, in about 0.6% when the femoral or iliac arteries are used, and in about 0.5% when the axillary or subclavian arteries are used. Mortality is estimated to be 30% but is more than double if not recognized until the postoperative period. Site of origin of dissection is most commonly the arterial inflow cannula (∼33%). Other common sites are the aortic cross-clamp or partial occlusion clamp (∼29%) and the proximal saphenous vein anastomosis site (14%). Sixty percent of cases occur during coronary artery bypass graft (CABG) surgery and 17% during aortic valve surgery with or without CABG. iAD may be somewhat less common in off-pump versus on-pump CABG but is still not very rare. Risk factors, presentation, diagnosis, and management are reviewed in detail as is the key role of the use of echocardiography in the early diagnosis of iAD and for guiding its management.

Effect of Pre-operative Angiotensinconverting Enzyme Inhibitors on Haemodynamic Parameters and Vasoconstrictor Requirements in Patients Undergoing Off-pump Coronary Artery Bypass Surgery

The effects of pre-operative angiotensin-converting enzyme inhibitor (ACEI) treatment on haemodynamic status and vasoconstrictor requirements during off-pump coronary artery bypass surgery (OPCAB) were studied. Eighty patients selected for OPCAB were divided into those who had been treated with ACEIs for 4 weeks or more pre-operatively (ACEI group) (n = 43) and those who had not been treated with ACEIs (control group) (n = 37). Noradrenaline was infused during the operation when the mean systemic arterial pressure (SAP) fell below 60 mmHg. No significant differences in the haemodynamic parameters measured were detected between the two groups, except for cardiac output, which was found to be significantly greater in the control group. During anastomosis of the obtuse marginal branch of the left circumflex artery (OM), a significantly larger amount of noradrenaline was required by the ACEI group compared with the control group. In conclusion, pre-operative treatment with ACEIs significantly increased the amount of vasoconstrictor necessary to maintain the target SAP during OM anastomosis during OPCAB.

Off-pump coronary artery bypass for a heparin-allergic patient

A 46-year-old man with no history of drug allergy developed acute myocardial infarction. Coronary angiographic findings revealed triple vessel disease. Serum hepatic enzymes were elevated due to heparin administered to control infarction, and an allergic reaction developed exclusively due to heparin. To avoid heparin use, we adopted heparin-free off-pump coronary artery bypass grafting through median sternotomy. The systemic anticoagulant agent argatroban was administered to maintain active clotting time over 200 seconds. The left internal thoracic artery was anastomosed to the left anterior descending artery, the radial artery to the diagonal branch, and the right gastroepiploic artery to the right coronary artery. Patency was confirmed by postoperative coronary angiography. No complications were noted. For patients with heparin allergy, off-pump coronary artery bypass grafting is a useful maneuver, because it can be conducted using anticoagulant agents other than heparin.

The effect of milrinone infusion on right ventricular function during coronary anastomosis and early outcomes in patients undergoing off-pump coronary artery bypass surgery

Background

During coronary anastomosis in off-pump coronary artery bypass surgery (OPCAB), hemodynamic alternations can be induced by impaired diastolic function of the right ventricle. This study was designed to examine the effect of milrinone on right ventricular function and early outcomes in patients undergoing OPCAB.

Methods

Forty patients undergoing OPCAB were randomly assigned in a double-blind manner to receive either milrinone (milrinone group, n = 20) or normal saline (control group, n = 20). Hemodynamic variables were measured after pericardiotomy (T1), 5 min after stabilizer application for anastomosis of the left anterior descending coronary artery (LAD, T2), the obtuse marginalis branch (OM, T3), the right coronary artery (RCA, T4), 5 min after sternal closure (T5), and after ICU arrival. The right ventricular ejection fraction (RVEF) and right ventricular volumetric parameters were also measured using the thermodilution technique. For evaluation of early outcomes, the 30-day operative mortality and morbidity risk models were used.

Results

There was no significant difference in hemodynamic variables, including mean arterial pressure, between the 2 groups, except for the cardiac index and RVEF. The cardiac index and RVEF were significantly greater at T3 in the milrinone group than in the control group.

Conclusions

Continuous infusion of milrinone demonstrated a beneficial effect on cardiac output and right ventricular function in patients undergoing OPCAB, especially during anastomosis of the graft to the OM artery, and it had no adverse effect on early outcomes.

The Best Bypass Surgery Trial: Rationale and design of a randomized clinical trial with blinded outcome assessment of conventional versus off-pump coronary artery bypass grafting

BACKGROUND

Recent trials suggest that off-pump coronary artery bypass grafting (OPCAB) reduces the risk of mortality and morbidity compared with conventional coronary artery bypass grafting (CCAB) using cardiopulmonary bypass. Patients with a moderate- to high-risk of complications after CCAB may have additional benefit from OPCAB.

METHODS

The Best Bypass Surgery Trial is a randomized, single center trial comparing the effects of OPCAB versus CCAB. The inclusion criteria are 3 vessel coronary heart disease affecting one of the marginal arteries, age>54 years, and EuroSCORE>or=5. The primary composite outcome measure consists of all-cause mortality, myocardial infarction, stroke, cardiac arrest, cardiogenic shock, and cardiac revascularization procedure. Follow up involves collection of data of mortality and morbidity via linkage to public registers, quality of life assessment at 3 and 12 months postoperatively and angiographic control at 12 months. The sample size of 330 patients was based on an estimated 75% one-year event free rate of the primary outcome measure in the OPCAB arm and 60% in the control arm with alpha=.05 and beta=.20. Accordingly, the trial will be able to detect an absolute risk reduction of 15% or a relative risk reduction of 37.5%. The median follow-up time is scheduled to 3 years.

RESULTS

Enrollment started in April 2002 and ended March 2006.

CONCLUSION

The results may have implications on the treatment modality of moderate- to high-risk patients scheduled for coronary artery bypass grafting.

Perioperative Patency of Coronary Artery Bypass Grafting is Not Influenced by Off-Pump Technique

BACKGROUND

Some concerns have been raised about technical accuracy and quality of distal anastomoses in off-pump myocardial revascularization (OPCAB), which could affect graft patency.

METHODS

Transit-time flowmetric results and clinical, enzymatic, and echocardiographic findings from 201 consecutive isolated on-pump coronary artery bypass graft cases (cardiopulmonary bypass coronary artery bypass grafting; group A) were compared with 96 consecutive OPCAB (group B) cases performed at our institution between January 2003 and December 2004. Maximum, mean, minimum flow, and pulsatility index were compared, stratifying the two groups according to graft type and coronaries revascularized. Graft flow reserve was evaluated in patients undergoing preoperative intraaortic balloon pump during baseline conditions and at a 1 to 1 ratio of intraaortic balloon pump augmentation.

RESULTS

No differences were recorded between the two groups in hospital mortality, perioperative myocardial infarction, postoperative enzymatic leakage, echocardiographic recovery, or hospital stay (p = not significant). Off-pump coronary artery bypass and cardiopulmonary bypass coronary artery bypass grafting demonstrated similar intraoperative maximum (75.8 +/- 10.4 mL/min vs 82.3 +/- 15.8; p = 0.190), mean (50.1 +/- 13.3 vs 46.3 +/- 7.7; p = 0.420), minimum flow (12.7 +/- 5.3 vs 11.9 +/- 5.4; p = 0.811), and pulsatility index (2.9 +/- 0.2 vs 2.6 +/- 0.8; p = 0.360). After stratifying the population according to graft type, no differences were detected between the two groups in transit-time flowmetric results of left internal mammary artery, radial artery, and single and sequential saphenous vein grafts. A one to one ratio of intraaortic balloon pump augmentation did not result in any difference in graft flow reserve when left internal mammary artery (p = 0.699), radial artery (p = 0.066), and saphenous vein graft anastomoses (p = 0.772) were considered.

CONCLUSIONS

Off-pump coronary artery bypass grafting and cardiopulmonary bypass coronary artery bypass grafting demonstrated similar clinical, biochemical, and transit-time flowmetric results, as well as comparable graft flow reserve. These data exclude a lower anastomotic quality in off-pump coronary artery bypass grafting.

Esophageal Doppler and thermodilution are not interchangeable for determination of cardiac output

PURPOSE

This study compares thermodilution cardiac output (TD-CO) and esophageal Doppler cardiac output (ED-CO) during periods of hemodynamic stability and after heart stabilization during off-pump coronary artery bypass (OPCAB) surgery.

METHODS

After Institutional Review Board approval, 58 patients undergoing OPCAB had simultaneous comparison of TD-CO and ED-CO at three time periods. Measurements were recorded, in a blinded manner, after probe insertion (T0), immediately before and after (T1,T2) heart displacement and before starting any pharmacological treatment (if needed) to maintain systolic blood pressure to its value before heart mobilization. Measurements were also taken before sternal closure (Tfinal).

RESULTS

Three hundred and two pairs of data were analyzed using the Bland and Altman method. Bias, standard deviation (SD) of the bias (precision), and degree of agreement (bias +/- 2 SD) were calculated. Based on published literature, we considered that the highest degree of agreement should be < 0.5 L.min(-1) to consider both methods as interchangeable. At T0, bias and SD of bias between TD-CO and ED-CO were -0.1 +/- 1.0 L.min(-1). Immediately before heart stabilization, bias +/- SD was 0.6 +/- 1.0 L.min(-1) and after heart displacement, 0.5 +/- 0.8 L.min(-1). At Tfinal, bias +/- SD was 0.7+/- 0.7 L.min(-1).

CONCLUSION

Because the degree of agreement was > 0.5 L.min(-1) at all measurement periods except T0, we conclude that TD and ED are not interchangeable at any time during OPCAB surgery.

Off-pump total arterial revascularization: our experience

BACKGROUND AND AIM

Off-pump coronary artery bypass grafting with both the internal thoracic arteries, such as the Tector technique, can reduce the morbidity associated with extracorporeal circulation and aortic cross-clamp. The aim of the present study is to describe our experience and the results obtained.

METHODS

From April 1998 to December 2003, the off-pump Tector technique was performed on 743 patients, of whom 621 were male (83.5%), with a mean age of 65.3 +/- 9.5 years (23-90). Preoperative risk factors were diabetes mellitus in 29.5% and peripheral vasculopathy in 14.7% of the patients. Angiography showed left main disease in 25.6% and triple-vessel disease in 50.3% of the patients, with a mean ejection fraction of 60%+/- 13% (23-88). Both the internal thoracic arteries were harvested using the skeletonization technique and were anastomosed as "Y" or "T" grafts. Intraoperative graft patency was checked using a Doppler flowmeter.

RESULTS

A total of 2028 distal anastomoses were performed, the average being 2.7 (1 to 5) per patient. At least three distal anastomoses were undertaken in 62% of the patients. Postoperative complications included atrial fibrillation in 40 patients (5.4%), myocardial infarction in 24 (3.2%), mediastinitis and reoperation for bleeding in 7 (0.9%) and stroke in 3 (0.4%). Twenty-four patients (3.2%) died in the first month postoperatively.

CONCLUSIONS

The off-pump Tector technique appears to be safe, showing a low surgical morbidity.

Que faut-il attendre de la chirurgie coronaire sans circulation extracorporelle ?

Coronary artery bypass surgery with beating heart (off-pump) has become more common in the last ten years allowing seven randomized studies with at least 60 patients, comparing off-pump and on-pump coronary bypass. Anaesthesia, monitoring and haemodynamic complications are described. Randomized studies concluded to less elevation of biochemical markers of myocardial and renal injury, less hydric inflation, less cerebral microemboli, reduction of homologous blood transfusions, of hospital stay and global costs. However in low risk patients no reduction in myocardial infarction, atrial fibrillation, stroke, acute renal failure, early reoperation, surgical site infection and mortality were observed. Non-randomized studies suggest a benefit in stroke and mortality in elderly patients but the possibility of incomplete revascularization remains.

Haemodynamic effects of a milrinone infusion without a bolus in patients undergoing off-pump coronary artery bypass graft surgery

The haemodynamic effects of a continuous infusion of milrinone without an initial bolus dose were evaluated in patients undergoing off-pump coronary artery bypass graft surgery. After internal mammary artery harvest, milrinone 0.5 microg.min(-1).kg(-1) (29 patients) or a normal saline infusion (33 patients) was started and continued until all graft anastomoses were completed. Haemodynamic variables were recorded before application of the tissue stabiliser, at 1, 3, 5 and 10 min after the application of the stabiliser, and after its removal. The administration of a milrinone infusion was associated with a smaller decrease in cardiac output and mixed venous oxygen saturation during all the coronary artery anastomoses, with no severe complications and a decreased dose of norepinephrine infused to maintain systemic arterial pressure.

Our experiences for off-pump coronary artery bypass grafting to the circumflex system

BACKGROUND

Complete revascularization has been difficult in off-pump coronary artery bypass grafting (OPCAB). Hemodynamic deterioration often prevents access to the circumflex territory. This study presents instrumentation for accessing the circumflex territory, and our clinical experience.

METHODS

From August 1999 through December 2002, 140 patients underwent OPCAB via sternotomy in our institution. The 114 requiring reconstruction of the circumflex artery are the subjects of this study. There were no exclusion criteria. A series of techniques and instruments were developed to provide access to the circumflex area while hemodynamic stability was preserved, including the left pericardial traction technique, compression of the right pericardium, a right sternal retractor, and a type of shunt tube.

RESULTS

Patients received an average of 3.2 grafts (range, 2 to 6). Complete revascularization was achieved in 95% of the cases. Complications included respiratory insufficiency (0.8%), renal dysfunction (7%), and sternal wound infection (0.8%). Blood transfusions were required in 10 patients (8%). No patient suffered perioperative myocardial infarction or stroke. No operation was converted to cardiopulmonary bypass. There was no operative death. Predischarge angiography demonstrated a 99% patency rate.

CONCLUSIONS

With our techniques and instruments, off-pump coronary revascularizaion of the circumflex area may be performed safely to achieve complete revascularization. Early clinical results are excellent, but long-term longitudinal follow-up is required to assess the future effectiveness of OPCAB procedure with our techniques.

Off-pump complete revascularization through a left lateral thoracotomy (ThoraCAB): the first 200 cases

BACKGROUND

Conventional coronary bypass surgery is associated with substantial morbidity caused by cardiopulmonary bypass (CPB) and median sternotomy. This report describes an innovative technique to perform complete revascularization through a lateral thoracotomy without CPB (thoraCAB).

METHODS

From February 2000 to April 2001 a total of 200 patients underwent thoraCAB. The patient is positioned with the left side elevated to 45 degrees. A 5- to 6-inch incision is made over the left fourth or fifth intercostal space from just medial to the nipple to the anterior axillary line. The left internal thoracic artery is harvested as a pedicle graft under vision. Proximal anastomoses are first completed on the ascending aorta, followed by the distal coronary anastomoses on the beating heart using a stabilizer. Intercostal nerve freezing is done using a cryoprobe.

RESULTS

Complete revascularization was achieved in all patients. The number of grafts averaged 2.9 +/- 1.08 per patient. One patient (0.5%) died of renal failure. Two patients (1%) were converted to CPB. No strokes were observed. Three patients (1.5%) required prolonged ventilation (>48 hours). Five patients (2.5%) had postoperative bleeding requiring reexploration. Of the patients, 16 (8%) developed new-onset postoperative atrial fibrillation.

CONCLUSIONS

ThoraCAB has been feasible in the vast majority of patients requiring coronary bypass surgery. The prevalence of postoperative atrial fibrillation was low. Postoperative pain maybe lessened with intercostal nerve freezing.

Intracardiac left ventricular support in beating heart, multi-vessel revascularization

BACKGROUND

Less invasive operation procedures without support of extracorporeal circulation are becoming increasingly important. A basic requirement for good long-term results in such cases is, however, the complete revascularization of the affected coronary vessels. The unsatisfactorily high conversion rate from bypass operations originally planned as off-pump to conventional operations with heart-lung machines, because of the failure to reach the target vessels on the rear wall of the heart through hemodynamic instability led to investigation of the efficiency of a microaxial pump (Impella elect) placed in the left ventricle.

METHODS

In a prospective project 15 of 38 consecutive patients selected for coronary revascularization with beating heart had a micro pump transaortically implanted in the left ventricle to support the heart during the operation with a flow rate of 2.5 to 3.9 l/min.

RESULTS

With 8 of 23 patients operated on without pump support, the operation had to be converted to conventional methods with a heart-lung machine. Only one patient out of the left-ventricle-supported group had to be further operated on conventionally because of a deep intramyocardial positioned left anterior descending coronary artery (LAD) (p < 0.05). The investigated laboratory parameters, especially creatine kinase (CK), CK-MB isoenzyme, and clotting showed no significant difference. There tended to be a higher blood loss recorded with the pump-supported patients.

CONCLUSION

In summary, it appeared that the application of a left ventricular coaxial pump with comparable results seemed to make possible complete revascularization in nearly all patients.

Partial inferior vena cava snaring to control ischemic left ventricular dysfunction

PURPOSE

To describe the hemodynamic and intraoperative transesophageal echocardiographic evaluation of cardiac systolic and diastolic function in a patient undergoing off-pump coronary artery bypass graft (OP-CABG) surgery who developed pulmonary artery hypertension controlled by inferior vena cava (IVC) snaring.

CLINICAL FEATURES

A 63-yr-old man was referred to our hospital for elective OP-CABG surgery. His preoperative ventriculopathy revealed a decreased systolic function (ejection fraction of 35%), and a mild mitral regurgitation. Intraoperatively, after application of the stabilizer and clamping of the diagonal artery, he developed a marked increase in pulmonary artery pressure (PAP) with a decrease in systemic arterial pressure, non responsive to iv norepinephrine and nitroglycerin. Transesophageal echocardiographic evaluation revealed a marked decrease in systolic function and presence of a restrictive diastolic filling pattern. Partial IVC snaring decreased the venous return and PAP decreased cardiac chamber dimensions, improved systolic function and improved diastolic filling pattern.

CONCLUSION

Partial IVC snaring was used successfully to treat a hemodynamically unstable patient with sudden increase in PAP caused by ischemic left ventricular failure during OP-CABG.

Current trends and technique in OPCAB surgery

BACKGROUND AND AIM OF THE STUDY

Aging of the population, increased surgical risk, and technical improvement have contributed to the recent revival of off pump coronary artery bypass surgery (OPCAB). We present our experience with the systematic use of this technique.

METHODS

Between September 1996 and June 2000, 500 OPCAB procedures were performed at the Montreal Heart Institute (95% of all procedures during time frame, single surgeon). Contraindications were unstable hemodynamics, intramyocardial left anterior descending artery, and reoperation with extensive adhesions. Stabilization was achieved with pericardial sutures and mechanical compression. Surgical strategy was to first bypass the culprit lesion. Anesthetic management consisted of adequate fluid loading and minimal use of alpha-agonist. This cohort was compared to a contemporary cohort of 1,444 patients operated with cardiopulmonary bypass (CPB).

RESULTS

Demographics and risk factors were comparable for all. OPCAB patients received more grafts (3.1 +/- 0.9 vs 2.9 +/- 0.7, p = 0.006), conversion rate was low (0.4%), and complete revascularization was achieved in 93%. Operative mortality and perioperative myocardial infarction were comparable in both groups. Transfusion need, CK-MB count, postoperative use of intra-aortic balloon pump, and creatinine increase were less significant in OPCAB. Postoperative hemorrhage, atrial fibrillation, prevalence of cerebrovascular accident, and hospital stay were comparable for both groups. These results are comparable to those currently reported in the literature.

CONCLUSION

OPCAB surgery in the current era has established its safety and short-term efficacy although long-term clinical results are still warranted. Considering the changing pattern in surgical practice, OPCAB surgery should remain a therapeutic option in modern cardiac surgery.

Experimental coronary artery occlusion: relevance to off-pump cardiac surgery

Mechanical coronary artery occlusion is required for minimally invasive direct coronary artery bypass and off-pump coronary artery bypass surgery. It is important that the method of occlusion be minimally traumatic. Chronic effects of these methods have never been studied. Temporary occlusion of coronaries utilizing suture snare, silastic loop snare, and bulldog clamp was carried out in 12 Yucatan pigs. Three animals each were sacrificed acutely and at 3, 6, and 12 months. The area of occlusion of each vessel was examined by light microscopy and the degree of damage recorded. In the animals sacrificed acutely, there was more damage using the suture snare than with the other 2 methods, but there was minimal damage at longer intervals. There was slight damage acutely and chronically with the bulldog technique. No damage was seen acutely with the silastic loop technique, but some late damage was found. The techniques of coronary artery dissection and occlusion used for minimally invasive and off-pump bypass surgery may contribute to early postoperative graft occlusion.

Changing pattern in beating heart operations: use of skeletonized internal thoracic artery

BACKGROUND

The use of skeletonized internal thoracic artery (ITA) was reported to be technically and hemodynamically beneficial in conventional coronary artery bypass grafting with cardiopulmonary bypass assistance. The purpose of this study is to evaluate the impact of changing from conventional to skeletonized ITA harvesting on early off-pump coronary artery bypass grafting outcome.

METHODS

Between 1996 and 2001, 640 patients underwent systematic off-pump coronary artery bypass grafting (single surgeon experience). The ITA was pedicled (P) in the first consecutive 440 patients and skeletonized (S) in the subsequent 200 consecutive patients. Mean age, preoperative risk factors, sex, number of involved territories, and incidence of reoperations were similar in both groups.

RESULTS

In group S, number of ITAs per patient (1.7 +/- 0.08 versus 1.2 +/- 0.05; p < 0.001), bilateral ITA (46% versus 27%; p < 0.001), ITA sequential grafts (27% versus 1%; p < 0.001), and T grafts (16% versus 3%; p < 0.001) were higher. Deep sternal infections were comparable in both groups (group S: 1%, group P: 1.2%; p = 0.38). Perioperative myocardial infarction, maximal creatinine kinase-MB level, and requirement for more than 24 hours of inotropic support were comparable in both groups. Thirty-day mortality was also similar (S: 1.7%, P: 1.6%).

CONCLUSIONS

Changing to routine use of skeletonized ITA in off-pump coronary artery bypass grafting is a safe alternative to routine pedicled ITA. In our experience, this procedure has facilitated the use of ITA anastomosis without increasing sternal wound complications.

Mechanisms of hemodynamic changes during off-pump coronary artery bypass surgery

PURPOSE

To describe the mechanisms of hemodynamic changes during off-pump coronary artery bypass graft surgery (OP-CABG).

SOURCE

Pertinent medical literature in the English and French languages was identified through a Medline computerized literature search and a manual search of selected articles, using off-pump coronary artery surgery, beating heart surgery, hemodynamic, and transesophageal echocardiography as key words. Human and animal studies were included.

PRINCIPAL FINDING

Hemodynamic variations in OP-CABG may be due to mobilization and stabilization of the heart, or myocardial ischemia occurring during coronary occlusion. Suction type and compression type stabilizers produce hemodynamic effects through different mechanisms. Heart dislocation (90 degrees anterior displacement) and compression of the right ventricle to a greater extent than the left ventricle are responsible for hemodynamic alterations when using suction type stabilizers. Compression of the left ventricular outflow tract and abnormal diastolic expansion secondary to direct deformation of the left ventricular geometry are proposed mechanisms for hemodynamic derangements with compression type stabilizer. Coronary occlusion during the anastomosis can have additional effects on left ventricular function, depending on the status of collateral flow. The value and limitations of electrocardiographic (ECG), hemodynamic and echocardiographic monitoring modalities during OP-CABG are reviewed.

CONCLUSIONS

In summary, hemodynamic changes which can either be secondary to the stabilization technique or to transient ischemia represent an important diagnostic challenge during off-bypass procedures. The mechanism can vary according to the stabilization system. Current monitoring such as ECG and hemodynamic monitoring are used but remain limited in establishing the cause of hemodynamic instability. Transesophageal echocardiography is used in selected patients to diagnose the etiology of hemodynamic instability and can direct therapy, particularly in those with severe myocardial systolic and diastolic dysfunction, mild to moderate mitral regurgitation, or for patients who are unstable during the procedure.

Off-pump coronary artery bypass grafting decreases morbidity and mortality in a selected group of high-risk patients

BACKGROUND

The ideal indication for off-pump coronary artery bypass grafting (OPCABG) has yet to be defined. High-risk surgical patients may benefit the most when cardiopulmonary bypass (CPB), aortic cross clamping, and cardioplegic arrest are avoided. The aim of this study was to determine whether off-pump coronary artery bypass grafting might decrease the operative morbidity and mortality in a select group of high-risk patients with multivessel coronary artery disease.

METHODS

Utilizing a Parsonnet risk stratification model we analyzed prospectively collected data on a cohort of high-risk coronary artery disease patients, which were operated on with beating-heart technology by the same group of surgeons in a tertiary care university medical center. High-risk patients were defined as those with a Parsonnet score of 15 or greater.

RESULTS

Fifty-seven multivessel disease OPCABG patients (over a period of 2 years) had markedly increased Parsonnet scores (24.3 +/- 10.6). The average ejection fraction of the patients was 42% (+/-12.3) and their age ranged from 52 to 85 years (mean 70.6 +/- 10.4, 26% women). Unstable angina was present in 42 patients (74%) and 10 patients underwent OPCABG within 24 hours of the occurrence of acute myocardial infarction. In addition to severe coronary artery disease 32% of the patients presented with congestive heart failure, insulin-dependent diabetes (18%), renal failure (22%), peripheral vascular disease (31%), pulmonary disease (18%), and neurologic disorders (14%). An average of 2.6 +/- 0.9 grafts/patient were performed and the posterior descending artery or marginal branches of the circumflex artery or both were grafted in 90%. The 30-day mortality rate was 3.5% (n = 2).

CONCLUSIONS

OPCABG can be performed with a reasonable low morbidity and mortality in this select group of high-risk patients. OPCABG is a reasonable, and might even be preferable, operative strategy in this high-risk group of patients.

Retropericardial hematoma complicating off-pump coronary artery bypass surgery

We report the case of a retropericardial hematoma after triple-vessel off-pump coronary artery bypass grafting. Transesophageal echocardiography demonstrated a retropericardial hematoma that compressed the left atrium anteriorly and suppressed cardiac function. Injury to the pulmonary vein during placement of deep pericardial sutures and postoperative infusion of heparin were the likely causes of this rare but potentially fatal complication of an off-pump bypass operation.

Complete revascularization in coronary artery bypass grafting with and without cardiopulmonary bypass

BACKGROUND

The feasibility of complete revascularization on the beating heart without cardiopulmonary bypass (CPB) as compared with the standard operation with CPB in elective low-risk patients with multivessel disease has not been clearly demonstrated in a prospective trial.

METHODS

Eighty selected low-risk patients were enrolled. In preoperative study with coronary angiography, the decision was made whether complete revascularization without CPB could be performed. Patients were randomly assigned to receive CABG either with (n = 40) or without CPB (n = 40). Randomization criteria were age, sex, and left ventricular ejection fraction. Completeness of revascularization as well as short- and mid-term clinical outcome in a 13.4 +/- 6.5 month follow-up period were monitored.

RESULTS

Twenty-six of 40 (65%) patients undergoing CABG without CPB underwent complete revascularization. In 5 of these patients (12.5%) suitable vessels were discarded for technical reasons and 9 patients (22.5%) were switched to CABG with CPB owing to the deeply intramyocardial course of target vessels (n = 5) or to hemodynamic instability (n = 4). In the group of patients operated on with CPB, 34 of 40 patients (85%) received complete revascularization. In 6 patients (15%) suitable vessels were discarded for technical reasons. Mean number of bypass grafts was 3.1 +/- 0.8 with CPB and 2.6 +/- 0.5 without CPB (p = 0.043). Clinical outcome and hospital stay were comparable in both groups. No patient died during the study period. No myocardial infarction was observed. Three patients undergoing CABG without CPB underwent successful PTCA 3 months after surgery.

CONCLUSIONS

CABG without the use of CPB is effective for complete revascularization in the majority of selected low-risk patients. Nevertheless, it has to be stated that the rate of incomplete revascularization in this early series of CABG without CPB is higher, and compromises the basic principle of complete revascularization.

Complete myocardial revascularization on the beating heart with epicardial stabilization: anesthetic considerations

OBJECTIVE

To describe an anesthetic management protocol for patients undergoing cardiac surgery with multiple coronary artery bypass grafts without cardiopulmonary bypass (off-pump CABG surgery) by median sternotomy with mechanical stabilization.

DESIGN

Retrospective nonrandomized analysis.

SETTING

Tertiary care hospital.

PARTICIPANTS

Sixty-six consecutive patients on whom off-pump CABG surgery by median sternotomy was attempted.

INTERVENTIONS

Anesthesia was induced with a combination of etomidate and fentanyl; pancuronium bromide was given for muscle relaxation; and anesthesia was maintained with isoflurane, desflurane, or sevoflurane in 100% oxygen. Maintenance of normothermia was attempted by keeping the room temperature at 70 degrees F, warming all fluids to 41 degrees C, and using 2.5 L/min of fresh gas flows and a heat and humidity exchanger. When available, a convective forced-air blanket was used to cover patients' head and shoulders. Patients who were not slated for revascularization of the circumflex vessels and who had good ventricular function received central venous pressure monitoring (26%); all other patients received a pulmonary artery catheter.

MEASUREMENTS AND MAIN RESULTS

Of the 66 patients, 36% required an epinephrine infusion at a mean rate of 1.45+/-2.05 microg/min intraoperatively to maintain hemodynamic stability; 25% required inotropic support for < 12 hours in the intensive care unit.

CONCLUSION

Institution of systematic hemodynamic management was associated with the successful completion of the surgical procedure in 61 patients (92%). Only 5 patients required conversion to regular CABG surgery with cardiopulmonary bypass.

Coronary revascularization of the circumflex system: different approaches and long-term outcome

BACKGROUND

Minimally invasive direct coronary artery bypass, without cardiopulmonary bypass, through a left lateral thoracotomy approach (lateral MIDCAB), is a safe alternative to coronary artery bypass surgery using cardiopulmonary bypass (on-pump CABG) of the circumflex system via median sternotomy. However, it is unknown whether lateral MIDCAB may yield an improved long-term outcome over the conventional on-pump median sternotomy approach.

METHODS

We compared the perioperative outcomes of patients undergoing lateral MIDCAB (n = 34) versus conventional on-pump CABG of the circumflex system (n = 16) from June 1996 to July 1999. The two groups were similar with respect to baseline characteristics and risk stratification. Patients who required only one or two grafts for complete revascularization were included.

RESULTS

Lateral MIDCAB patients had a lower need than on-pump CABG patients for intraoperative (12% MIDCAB vs 43% on-pump CABG, p = 0.03) and postoperative transfusions (29% vs 69%, p = 0.01), had fewer neuropsychologic changes (0% vs 19%, p = 0.03), and had a lower rate of postoperative atrial fibrillation (12% vs 44%, p = 0.02). Lateral MIDCAB was also associated with a significantly lower postoperative length of stay (5 +/- 2 vs 7 +/- 3 days, p = 0.02). Actuarial survival at a mean period of follow-up of 19 +/- 11 months was 97% for the lateral MIDCAB versus 88% for the on-pump CABG group (p = 0.6). Event-free survival was 88% for lateral MIDCAB versus 81% for on-pump CABG (p = 0.1).

CONCLUSIONS

Lateral MIDCAB may safely be performed in patients with isolated coronary artery disease of the circumflex system with improved early morbidity and an abbreviated hospital stay compared with conventional median sternotomy on-pump CABG.

Off-pump coronary artery bypass grafting: initial experience at one community hospital

BACKGROUND

This study reports one cardiac surgical center's experience with off-pump coronary artery bypass (OPCAB) and compares clinical risk factors and outcomes with a group of patients undergoing coronary artery bypass grafting (CABG) with cardiopulmonary bypass at the same institution.

METHODS

Data on preoperative risk factors, intraoperative clinical markers, and postoperative outcomes were collected prospectively on all patients undergoing cardiac surgical procedures at our institution. From January 1, 1999, through October 7, 1999, 332 patients underwent OPCAB procedures at our institution. This group was compared with 445 consecutive patients undergoing CABG at the same institution during the period of January 1, 1998, through November 30, 1998.

RESULTS

The two groups were similar with respect to preoperative clinical risk factors. Intraoperative data showed OPCAB patients tended to have fewer grafts performed and had a lower frequency of multiple grafts to obtuse marginal vessels. Outcomes showed no differences in the incidence of perioperative stroke, mediastinitis, reexploration for bleeding, pulmonary complications, new renal failure, postoperative atrial fibrillation, or transfusion of blood products. Patients in the OPCAB group had fewer perioperative myocardial infarctions and lower incidence of postoperative low cardiac output syndrome. A higher percentage of OPCAB patients had surgical lengths of stay of 5 days or less. The OPCAB group tended to have a lower in-hospital mortality rate but this difference did not reach statistical significance.

CONCLUSIONS

Off-pump coronary artery bypass grafting with revascularization of all coronary artery segments is a safe and effective procedure that can be performed with equal or improved outcomes and shorter surgical lengths of stay compared with CABG with cardiopulmonary bypass.

Midterm angiographic assessment of coronary artery bypass grafting without cardiopulmonary bypass

BACKGROUND

Coronary bypass surgery that provides good long-term graft patency can be performed on the beating heart as a viable alternative to conventional coronary artery bypass grafting (CABG).

METHODS

From September 1993 to December 1996, 696 patients underwent CABG on the beating heart at the Koşuyolu Heart and Research Hospital in Istanbul. Among them, 70 patients were chosen randomly for angiographic assessment of off-pump coronary artery bypass grafting.

RESULTS

The interval from operation to angiography varied from 24 to 61 months (mean, 36.1+/-10.9 months). The patency rate of left internal mammary-left anterior descending artery anastomoses was 95.59% (patency achieved in 65 of 68 patients) and of vein grafts was 47.06% (patency achieved in 16 of 34 patients) (p < 0.0001). The patency rates of grafts anastomosed to the left anterior descending artery were significantly higher than the rates of the grafts anastomosed to the other coronary arteries (95.71% versus 45.45%, p < 0.0001). Multivariate analysis showed that graft type (p < 0.0001) and hyperlipidemia (p = 0.023) were significant predictors for graft occlusion. Left ventricular function improved significantly after CABG (p = 0.04). Reintervention (using percutaneous transluminal cardiac angioplasty) and reoperation rates were 0.97% and 1.4%, respectively.

CONCLUSIONS

Off-pump coronary artery bypass grafting appears to produce midterm and long-term patency rates that are comparable to those of conventional techniques; that is especially true in cases of arterial conduits and of conduits anastomosed to the left anterior descending artery.

Right heart mini-pump bypass for coronary artery bypass grafting: experimental study

BACKGROUND

Visualization of the left circumflex arteries during off-pump coronary artery bypass grafting (CABG) causes hemodynamic disturbance. We investigated whether right heart mini-pump bypass (RHB), using a centrifugal pump, improved the safety of this procedure by studying the influences of different heart displacement positions, the Trendelenburg maneuver and RHB on hemodynamics.

METHOD

Hemodynamic parameters in eight mongrel dogs (15.5-20 kg) were continuously monitored at a fixed heart rate of 80 beats/min through a conventional median sternotomy. The posterior descending artery (PDA) and left circumflex artery (LCX) were exposed using an Octopus tissue stabilizer. After evaluating the influence of the Trendelenburg maneuver on hemodynamics, a heparin-coated centrifugal pump without an oxygenator was introduced and the impact of different pump flow volumes was investigated during RHB.

RESULTS

LCX exposure caused significant decreases in aortic flow (to 35. 1+/-12.8%) and arterial mean pressure (to 66.1+/-9.3%) compared with baseline (P<0.001). In contrast to PDA exposure, values remained significantly decreased during the Trendelenburg maneuver. On the contrary, RHB significantly improved the hemodynamic impairments caused by both heart displacement procedures, especially LCX exposure, although 100% pump flow significantly increased left atrial pressure to 131.3+/-19.5% (P<0.01).

CONCLUSION

Exposure of the LCX caused severe hemodynamic deterioration, which was not fully reversed by the Trendelenburg maneuver. In contrast, RHB significantly improved hemodynamics, and therefore this technique can be beneficial for CABG of LCX in the limited cases.

[Total arterial myocardial revascularization with both mammary arteries without extracorporeal circulation]

INTRODUCTION

Tector has described the off-pump total arterial revascularization technique, using multiple anastomosis with both internal thoracic arteries. To reduce surgical morbid-mortality, we have proposed the use of this technique without extracorporeal circulation.

PATIENTS AND METHODS

From April, 1998 the off-pump <<Tector>> technique was performed in 92 patients, 74 male (80%) and 18 female (20%), with a mean age of 64.9+/-8.1 years (42-78). Preoperative angiography demonstrated triple-vessel disease in 58 (63%) patients, and left main disease was present in 19 (20.5%) patients. Forty patients (43.5%) showed unstable angina, 24 patients (26%) significant peripheral vascular disease, and 26 (28%) diabetes mellitus. Both internal thoracic arteries were harvested using the skeletonization technique and were used like a <<T or T>> graft. The flow in the graft was measured using a flowmeter, and in 24 (26%) patients by angiographic study.

RESULTS

A total of 274 distal anastomoses were performed, 122 (44.6%) in the lateral or inferior wall, and 69 (25.2%) were sequential, with an average of 2.98 bypass/patient. In 59.8% of the patients a triple bypass was performed, 22% double bypass, 17% cuadruple bypass and 1 patient a quintuple bypass. During the initial six hours 64.9% of patients were extubated. Only one patient (1.1%) needed intraaortic ballon pumping and 3 (3.2%) inotropics during the postoperative course. Hospital mortality was 3 (3.2%) patients. Reoperation for bleeding was needed in just one patient (1.1%), and 78.3% of patients were not transfused. Mediastinitis occurred in 3 patients (3.2%). Postoperative stroke was not observed. At 7.7+/-2.8 months of mean follow-up all patients were free of symptoms and the global patency rate of 94%.

CONCLUSIONS

Off-pump Tector technique appears to be safe, offering a complete arterial revascularization and showing a reduction of surgical morbidity.

Systematic off-pump coronary artery revascularization: experience of 275 cases

BACKGROUND

The author reports his short-term experience with systematic off-pump coronary artery revascularization in multivessel disease.

METHODS

Between September 1996 and October 1998, 275 off-pump revascularizations (83% of case load during this period; 97% since January 1998) were performed by a single surgeon (R.C.). The patient base of 216 men/59 women averaged 63 +/- 10 years. Main indication was unstable angina (60%). All surgeries were performed through a median sternotomy, with mechanical stabilization, and a heart "verticalizing" technique to enable access to the circumflex territory.

RESULTS

An average of 2.91 +/- 0.83 (range 1 to 5) grafts/patient was achieved, with 70% of cases being triple or quadruple bypasses. Single or double internal thoracic arteries was utilized in 95% of cases. Complete revascularization was attained in 93% of surgeries. Total ischemic time averaged 28 +/- 10 (range 8 to 65) minutes. Myocardial infarction incidence was 4%, with only 1 patient requiring postoperative aortic counter-pulsation assistance. One early percutaneous transluminal coronary angioplasty was needed to restore an occluded posterior descending artery. Three operative deaths resulted. One conversion to cardiopulmonary bypass was required. A transfusion rate of 32% was observed, half the rate of conventional coronary artery bypass grafting at our institute.

CONCLUSIONS

With gradual experience, proper operative technique, and surgical apparatus, beating heart bypass surgery may be used systematically as a suitable, safe alternative to conventional on-pump coronary artery bypass grafting, permitting complete revascularization in a majority of patients with excellent short-term results.

Pulmonary hypertension during beating heart coronary surgery: intermittent inferior vena cava snaring

Pulmonary hypertension during beating heart coronary artery bypass grafting may compromise the possibility of safely completing the procedure off-pump. To obviate such a problem, we describe a simple technique by which the inferior vena cava is progressively snared to decrease pulmonary pressure.