Beating versus arrested heart revascularization: evaluation of myocardial function in a prospective randomized study

Off pump coronary artery bypass surgery for significant left ventricular dysfunction: safety, feasibility, and trends in methodology over time--an early experience

OBJECTIVE

To examine the safety and applicability of off pump coronary artery bypass surgery (OPCAB) in patients with significant left ventricular dysfunction and to discuss the clinical implications for the surgical methods.

DESIGN

Retrospective study.

SETTING

Tertiary care university affiliated referral centre.

PARTICIPANTS

353 consecutive patients with preoperative left ventricular ejection fraction < or = 35% who underwent coronary artery bypass over a three year period.

MAIN OUTCOME MEASURES

Postoperative morbidity and mortality.

METHODS

144 patients operated by OPCAB were compared with 209 patients operated by conventional coronary artery bypass. Multivariate and univariate analyses were performed on the pre- and postoperative variables to predict risk factors associated with hospital morbidity and mortality.

RESULTS

Patients in the OPCAB group were more likely to be women and to have congestive heart failure, chronic obstructive pulmonary disease, hypertension, and diabetes; patients in the on pump group were more likely to have had a recent myocardial infarction and to have more severe angina pectoris and an urgent/emergent status. The groups did not differ significantly in length of stay, major postoperative complication rates, or mortality. Comparison of the impact of the procedures on surgical methods over time showed an increase in the use of OPCAB (13% to 67%), without any impact on morbidity or mortality.

CONCLUSIONS

OPCAB is feasible and applicable for patients with depressed left ventricular function. This high risk group can potentially benefit from the off pump approach.

Safety, efficacy, and cost of intraoperative cell salvage and autotransfusion after off-pump coronary artery bypass surgery: A randomized trial

OBJECTIVE

We evaluated, in a randomized controlled trial, the safety and effectiveness of intraoperative cell salvage and autotransfusion of washed salvaged red blood cells after first-time coronary artery bypass grafting performed on the beating heart.

METHODS

Sixty-one patients undergoing off-pump coronary artery bypass grafting surgery were prospectively randomized to autotransfusion (n = 30; receiving autotransfused washed blood from intraoperative cell salvage) or control (n = 31; receiving homologous blood only as blood-replacement therapy). Homologous blood was given according to unit protocols.

RESULTS

The groups were well matched with respect to demographic and comorbid characteristics. Patients in the autotransfusion group had a significantly higher 24-hour postoperative hemoglobin concentration (11.9 g/dL; SD, 1.41 g/dL) than those in the control group (10.5 g/dL; SD, 1.37 g/dL) (mean difference, 1.02 g/dL; 95% confidence interval, 1.60-0.44 g/dL; P = .0007), as well as a 20% reduction in the frequency of homologous blood product use (11/31 vs 5/30; P = .095). Autotransfusion of washed red blood cells was not associated with any derangement of thromboelastograph values or laboratory measures of clotting pathway function (prothrombin time, activated partial thromboplastin time, and fibrinogen levels), increased postoperative bleeding, fluid requirements, or adverse clinical events. There was no statistical difference between groups in the total operation, hospitalization, and management costs per patient (median difference, USD 1015.90; 95% confidence interval, -USD 2260 to USD 206; P = .11). Conclusions Intraoperative cell salvage and autotransfusion was associated with higher postoperative hemoglobin concentrations, a modest reduction in transfusion requirements, no adverse clinical or coagulopathic effects, and no significant increase in cost compared with controls. This study supports its routine use in off-pump coronary artery bypass grafting surgery.

Off-pump coronary artery bypass grafting does not reduce lymphocyte activation

OBJECTIVE

In this study, we test the hypothesis that off-pump coronary bypass surgery might result in less lymphocyte activation than on-pump coronary surgery. We also study the behavior of lymphocyte activation markers during and after surgery.

BACKGROUND

Coronary artery bypass surgery is known to be associated with changes of inflammatory mediators, immune function, and early phase lymphocyte activation, which could cause postoperative lymphopenia and lymphocyte unresponsiveness.

METHODS

We studied lymphocyte activation response in 28 patients randomized to off-pump (n = 13) or on-pump (n = 15) coronary artery bypass surgery. Expression of CD25, CD26, CD69, and DR on T (CD3+) and B (CD19+) lymphocytes on peripheral blood was assessed through flow cytometry.

RESULTS

The response of T lymphocytes and their activation markers, as well as B lymphocytes and their activation markers, was similar after on- and off-pump surgery. Overall, T lymphocytes decreased to the lowest level 9 h after surgery and tended to increase later. For B lymphocytes, there was early reduction with increase on the 1st postoperative day. There was early activation of CD69+ and late activation of CD25+ on T lymphocytes. For B lymphocytes, there was early activation of CD69+ and late activation of DR+.

CONCLUSIONS

(1) Compared to on-pump cardiopulmonary bypass, off-pump surgery does not reduce lymphocyte activation. (2) Coronary bypass surgery causes the early activation of lymphocytes, as evidenced by the increased expression of lymphocyte activation markers.

On-Pump/Beating-Heart Myocardial Protection for Isolated or Combined Coronary Artery Bypass Grafting in Patients with Severe Left Ventricle Dysfunction: Assessment of Myocardial Function and Clinical Outcome

BACKGROUND

Myocardial protection in coronary artery bypass grafting (CABG) with severe left ventricular (LV) dysfunction is still a surgical dilemma. Preoperative myocardial infarction (MI) and postoperative low output syndrome are serious complications in cases of inadequate protection of the heart, which has limited myocardial reserve. The aim of this study was to evaluate myocardial function and clinical outcome after on-pump/beating-heart CABG in patients with severe LV dysfunction.

METHODS

Between March 2001 and March 2004, clinical, operative, and postoperative data were prospectively collected from patients with LV ejection fraction (EF) < 30% who underwent on-pump/beating-heart CABG and associated procedures.

RESULTS

There were 46 patients and the mean patient age was 58.38 +/- 9.23. The mean EF was 25.6 +/- 2.8%. Operating time was 275 +/- 63 minutes. The frequency of distal anastomosis was 3.06 +/- 1.04. Twenty-four patients required aneurysmectomy in addition to CABG, and 2 of the 24 required mitral repairs. Inotropic support was required in 14 patients (30%) and 5 of them (10.9%) also required IABP. The LV EF improved significantly after the operation when compared to preoperative measurements (25.6 +/- 2.8 versus 33.64 +/- 4.69, P < .05). Hospital mortality rate was 4.3% (2 of the 46 patients). No mortality was observed at a mean followup of 16 months after discharge from the hospital.

CONCLUSIONS

On-pump/beating-heart CABG technique is effective in protecting myocardial functions in patients with severe LV dysfunction. The main advantage of the on-pump/beating-heart technique is the ability it provides one to perform complete revascularization, and intracavitary procedures with low morbidity and mortality even in impaired LV function.

Routine reoperative off-pump coronary artery bypass grafting via midline sternotomy: is it feasible?

Multivessel off-pump coronary artery bypass (OPCAB) has been conducted safely; however, the clinical outcomes of reoperative OPCAB have not been reported clearly. Currently OPCAB is being performed systematically in this institution including reoperative surgeries. Between September 1, 1999, and December 31, 2003, reoperative OPCAB via midline sternotomy was planned for nonemergent patients with normal left ventricular function without valvular disease. The perioperative results of patients who underwent reoperative OPCAB were analyzed. Thirty-five patients were scheduled for OPCAB. Of these, OPCAB was performed in 27 patients, giving OPCAB success rate of 77.1%. Failure of OPCAB was due to graft injury in 2, ischemic EKG change in 1, and dense adhesion and difficulty of dissection in 5 patients. The mean number of grafts with completed OPCAB was 3.0 +/- 1.5. There were no hospital deaths, strokes, or respiratory or renal failures. One patient (3.7%) developed perioperative myocardial infarction. Postoperative angiography was obtained in 12 patients (26 distal anastomoses), and all anastomoses were perfect except for 1 distal anastomosis stenosis, giving an overall stenosis-free patency rate of 95.1%. During a follow-up period (mean 2.5 +/- 0.6 years), all patients survived without cardiac event, except 1 patient who underwent catheter intervention. Cardiopulmonary bypass may be required during cardiac dissection to decompress the heart and to facilitate dissection. However, once lysis of the adhesion is completed, reoperative OPCAB can be performed without increasing surgical risks. Midterm results were satisfactory.

Hypercoagulability affecting early vein graft patency does not exist after off-pump coronary artery bypass

OBJECTIVE

Hypercoagulability may compromise the patency of bypass grafts. The authors hypothesized that perioperative in vitro platelet responses to varying agonists (eg, thrombin, platelet activating factor, collagen, adenosine diphosphate) correlate with early graft thrombosis after off-pump coronary artery bypass grafting (OPCAB).

DESIGN AND PARTICIPANTS

Prospective study of 78 OPCAB patients with 151 venous bypass grafts treated with perioperative aspirin and intraoperative heparin (250 U/kg).

SETTING

Tertiary, academic medical center.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Hypercoagulability, defined by TEG (maximum amplitude [MA]>70 mm), whole-blood aggregometry (>15 ohms after 5 mcl/mL collagen) or hemoSTATUS (Ch5CR>0.5), was serially assessed around OPCAB. An immediate decline in platelet function after surgery and on postoperative day 1 returned to normal by postoperative day 3 in most patients. Graft blood flow was analyzed intraoperatively, and vein biopsies were analyzed for endothelial disruption. Graft patency was assessed by multichannel computed tomography coronary angiography on postoperative day 5. No differences in any of the platelet function assays were noted for the 8 patients with graft thrombosis (n=8 grafts) versus the 68 patients with all patent grafts (n=129 grafts). Ten patients developed a rise in platelet function postoperatively >1 SD above baseline; only 1 developed graft thrombosis (p=not significant v patients with normal platelet function).

CONCLUSIONS

OPCAB is not associated with a significant activation in postoperative platelet function. This study suggests that if hypercoagulability exists after OPCAB, it is not involved in the pathogenesis of arterial thrombotic events such as early bypass graft failure.

The systemic inflammatory response syndrome and cardiopulmonary bypass

Cardiac surgery using cardiopulmonary bypass (CPB) provokes a systemic inflammatory response. This is mainly triggered by contact activation of blood by artificial surfaces of the extracorporeal circuit. Although often remaining sub-clinical and resolving promptly at the end of CPB, in its most extreme form this inflammatory response may be associated with the development of the systemic inflammatory response syndrome (SIRS) that can often lead to major organ dysfunction (MODs) and death. Here, we review the pathophysiology behind the development of this "whole body" inflammatory response and some of the methods currently used to minimise it.

Predictors of gastrointestinal complications after conventional and beating heart coronary surgery

BACKGROUND

Gastrointestinal complications after cardiac surgery remain a significant problem despite improvements in pre-operative, operative and post-operative care. The pathophysiology is uncertain, and their prevention remains suboptimal. This prospective, randomised study was designed to define the role of cardiopulmonary bypass (CPB) and cardioplegic arrest in the pathogenesis of gastrointestinal complications following coronary artery surgery.

METHODS AND RESULTS

Three hundred patients were prospectively randomised to (1) on-pump conventional coronary artery surgery [150 patients, 114 men, mean age 64 (45-75 years)] with mild hypothermic (32c) CPB and cardioplegic arrest of the heart or (2) off-pump surgery [150 patients, 113 men, mean age 64 (38-66) years] on the beating heart. The association of perioperative factors with gastrointestinal complications was investigated by univariate analysis. Significant variables were then included into a stepwise logistic regression model to ascertain their independent influence on the occurrence of gastrointestinal complications. There were no significant baseline differences between the groups. Eleven patients in the on-pump group and one patient in the off-pump group had post-operative gastrointestinal complications. Univariate analysis showed that CPB inclusive of cardioplegic arrest, left ventricular ejection fraction <50%, emergency surgery, prolonged aortic cross clamp and CPB time, post-operative low cardiac output syndrome, post-operative inotropic requirement, new onset atrial fibrillation (AF), excessive post-operative blood loss and redo thoracotomy <24 hours were predictors of gastrointestinal complications after coronary artery surgery (all p<0.05). However, stepwise multivariate regression analysis identified CPB inclusive of cardioplegic arrest as the only predictor of post-operative gastrointestinal complications (OR7.4; CI 3.4-17.9).

CONCLUSIONS

Cardiopulmonary bypass, inclusive of cardioplegic arrest, is the main independent predictor of post-operative gastrointestinal complications in patients undergoing coronary revascularisation.

Side Effects of Cardiopulmonary Bypass:. What Is the Reality?

Despite many years of clinical and experimental research, the contribution of cardiopulmonary bypass (CPB) and cardioplegic arrest to morbidity and mortality following cardiac surgery remains unclear. This is due, in part, to lack of suitable control group against which bypass and cardioplegic arrest can be compared. The recent success of beating heart coronary artery bypass grafting has, however, for the first time, provided an opportunity to compare the same operation, in similar patient groups, with, or without CPB and cardioplegic arrest. CPB is associated with an acute phase reaction of protease cascades, leucocyte, and platelet activation that result in tissue injury. This is largely manifest as subclinical organ dysfunction that produces a clinical effect in those patients that generate an excessive inflammatory response or in those with limited functional reserve. The contribution of myocardial ischemia/reperfusion, secondary to aortic cross-clamping, and cardioplegic arrest, to the systemic inflammatory response and wider organ dysfunction is unknown, and requires further evaluation in clinical trials.

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.

Value of delayed-enhancement cardiovascular magnetic resonance imaging in predicting myocardial viability after surgical revascularization

BACKGROUND

Despite the accepted utility of delayed-enhancement MRI in identifying irreversible myocardial injury, no study has yet assessed its role as a viability tool exclusively in the setting of coronary artery bypass surgery (CABG), and no study has repeated delayed-enhancement MRI late after revascularization. In a clinical trial in which patients underwent CABG by either the off-pump or on-pump surgical technique, we hypothesized that (1) preoperative delayed-enhancement MRI would have high diagnostic accuracy in predicting viability and (2) the occurrence of perioperative myocardial necrosis would affect late regional wall motion recovery.

METHODS AND RESULTS

Fifty-two patients undergoing multivessel CABG were studied by preoperative and early (day 6) and late (6 months) postoperative cine MRI for global and regional functional assessment and delayed-enhancement MRI for assessment of irreversible myocardial injury. Preoperatively, 611 segments (21%) had abnormal regional function, whereas 421 segments (14%) showed evidence of hyperenhancement. At 6 months after revascularization, 57% (343 of 611) of dysfunctional segments improved contraction by at least 1 grade. When all preoperative dysfunctional segments were analyzed, there was a strong correlation between the transmural extent of hyperenhancement and the recovery in regional function at 6 months (P<0.001). Of a total of 96 previously dysfunctional but nonenhancing or minimally hyperenhancing myocardial segments that did not improve regional function at 6 months, 35 (36%) demonstrated new perioperative hyperenhancement in the early postoperative MRI scan.

CONCLUSIONS

Delayed-enhancement MRI is a powerful predictor of myocardial viability after surgery, suggesting an important role for this technique in clinical viability assessment.

Trainees operating on high-risk patients without cardiopulmonary bypass: a high-risk strategy?

BACKGROUND

The safety of teaching off-pump coronary artery bypass grafting to trainees is best tested in high-risk patients, who are more likely to experience significant morbidity after surgery. This study compared outcomes of off-pump coronary artery bypass grafting operations performed by consultants and trainees in high-risk patients.

METHODS

Data for consecutive patients undergoing off-pump coronary artery bypass grafting were collected prospectively. Patients satisfying at least one of the following criteria were classified as high-risk: age older than 75 years, ejection fraction less than 0.30, myocardial infarction in the previous month, current congestive heart failure, previous cerebrovascular accident, creatinine greater than 150 micromol/L, respiratory impairment, peripheral vascular disease, previous cardiac surgery, and left main stem stenosis greater than 50%. Early morbidity, 30-day mortality, and late survival were compared.

RESULTS

From April 1996 to December 2002, 686 high-risk patients underwent off-pump coronary artery bypass grafting revascularization. Operations by five consultants (416; 61%) and four trainees (239; 35%) were the focus of subsequent analyses. Nine visiting or research fellows performed the other 31 operations. Prognostic factors were more favorable in trainee-led operations. On average, consultants and trainees grafted the same number of vessels. There were 18 (4.3%) and 5 (1.9%) deaths within 30 days, and 14 (3.4%) and 5 (1.9%) myocardial infarctions in consultant and trainee groups, respectively. After adjusting for imbalances in prognostic factors, odd ratios for almost all adverse outcomes implied no increased risk with trainee operators, although patients operated on by trainees had longer postoperative stays and were more likely to have a red blood cell transfusion. Kaplan-Meier cumulative mortality estimates at 24-month follow-up were 10.5% (95% confidence interval, 7.7% to 14.2%) and 6.4% (95% confidence interval, 3.8% to 10.9%) in consultant and trainee groups, respectively (hazard ratio = 0.60 [95% confidence interval, 0.37 to 0.99]; p = 0.05).

CONCLUSIONS

Off-pump coronary artery bypass grafting surgery in high-risk patients can be safely performed by trainees.

Beating versus arrested heart coronary revascularization: evaluation by cardiac troponin I release

BACKGROUND

This prospective randomized study aimed to compare beating and arrested heart revascularization in patients undergoing first elective coronary artery bypass graft, with cardiac troponin I release used to evaluate myocardial injury.

METHODS

Seventy patients were randomly assigned to a beating or arrested heart revascularization group. Cardiac troponin I concentrations were measured in serial venous blood samples drawn preoperatively in both groups: after aortic unclamping at 6, 9, 12, and 24 hours in the arrested heart group and after the last anastomosis at 6, 9, 12, and 24 hours in the beating heart group. Analysis of covariance with repeated measures was performed to test the effect of group and time on cardiac troponin I concentration.

RESULTS

The total amount of cardiac troponin I released was higher in the arrested heart revascularization group than in the beating heart revascularization group (8.25 +/- 6.16 vs 3.18 +/- 4.75 microg, p < 0.0001). Cardiac troponin I concentrations were significantly higher in the arrested heart group at hours 6, 9, 12, and 24 than in the beating heart group (p < 0.0001).

CONCLUSIONS

The lower release of cardiac troponin I in the beating heart revascularization group indicates that conventional coronary artery bypass graft with cardioplegic arrest causes more damage to the heart than off-pump myocardial revascularization.

Off-pump coronary artery bypass surgery: physiology and anaesthetic management †

Increasing interest is being shown in beating heart (off-pump) coronary artery surgery (OPCAB) because, compared with operations performed with cardiopulmonary bypass, OPCAB surgery may be associated with decreased postoperative morbidity and reduced total costs. Its appears to produce better results than conventional surgery in high-risk patient populations, elderly patients, and those with compromised cardiac function or coagulation disorders. Recent improvements in the technique have resulted in the possibility of multiple-vessel grafting in all coronary territories, with a graft patency comparable with conventional surgery. During beating-heart surgery, anaesthetists face two problems: first, the maintenance of haemodynamic stability during heart enucleation necessary for accessing each coronary artery; and second, the management of intraoperative myocardial ischaemia when coronary flow must be interrupted during grafting. The anaesthetic technique is less important than adequate management of these two major constraints. However, experimental and recent clinical data suggest that volatile anaesthetics have a marked cardioprotective effect against ischaemia, and might be specifically indicated. OPCAB surgery requires team work between anaesthetists and surgeons, who must be aware of each other's constraints. Some surgical aspects of the operation are reviewed along with physiological and anaesthetic data.

High risk coronary artery bypass patient: incidence, surgical strategies, and results

BACKGROUND

To describe our experience in the treatment of high risk coronary artery bypass patients and compare patients assigned to on-pump or off-pump surgery.

METHODS

During a 42-month period 306 high risk (Euroscore > 5) coronary artery bypass patients were consecutively treated at our institution. On the basis of the coronary anatomy and possibility of achieving a complete revascularization, 197 patients were assigned to off-pump and 109 to on-pump operation. Overall mortality was 6.2% (19 of 306 patients).

RESULTS

Although patients treated off-pump had a better cardiac status, no clinical advantages related to the avoidance of cardiopulmonary bypass were found in the overall population. Off-pump patients had more early and late cardiac complications, whereas patients operated on-pump exhibited an higher incidence of postoperative systemic organ dysfunction. Off-pump surgery improved in-hospital outcome only in the subset of patients at highest risk.

CONCLUSIONS

Avoidance of cardiopulmonary bypass does not confer significant clinical advantages in all high risk coronary patients; instead, there are particular subsets of patients in whom beating heart surgery can be particularly indicated and others for whom on-pump revascularization appears a better solution. Adaptation of the operation to the single patient is probably the way to improve outcome.

Cardiac biomarker release after CABG with different surgical techniques

OBJECTIVE

To investigate the release of cardiac biomarkers (troponin I and CK-MB) in patients undergoing coronary artery bypass graft (CABG) with or without cardiopulmonary bypass (CPB).

DESIGN

Prospective study.

SETTING

University tertiary hospital.

PARTICIPANTS

Sixty-five consecutive patients undergoing coronary artery bypass grafting (>or=2 vessel disease, ejection fraction >or=0.35%, elective procedure).

INTERVENTIONS

Cardiac biomarkers were measured before surgery, at intensive care unit arrival, 4 and 18 hours after the end of the procedure.

MEASUREMENTS AND MAIN RESULTS

Cardiac biomarker release was higher in on-pump than in off-pump patients at every time point. On multivariate analysis, CPB (p < 0.0001), number of distal grafts (p = 0.005), and hypertension treatment (p = 0.03) were the only independent predictors of peak cardiac troponin release.

CONCLUSIONS

Cardiac troponin I release after multivessel CABG is associated with the technique. Different values for the normal range should be considered. OPCABG is minimally invasive for the heart as far as myocardial marker release is concerned.

Off-pump versus on-pump myocardial revascularization in low-risk patients with one or two vessel disease: perioperative results in a multicenter randomized controlled trial

BACKGROUND

To evaluate hospital mortality and morbidity after myocardial revascularization in a prospective and multicenter study, comparing on-pump versus off-pump in a special subset of patients with lesions in the left descending artery, alone or associated with the right coronary artery.

METHODS

A multicenter prospective randomized study was performed. One hundred and sixty selected low-risk patients were enrolled; 80 patients were operated on-pump (coronary artery bypass grafting [CABG], group I) and 80 patients were operated off-pump (off-pump coronary artery bypass [OPCAB], group II). One hundred and five were male and ages ranged from 39 to 70 years old; mean 58.81 +/- 9.31 and median 59. Preoperative clinical characteristics were similar in both groups; only previous myocardial infarction was higher in the OPCAB group. Patients with severe left ventricular dysfunction (FE </= 35%), renal failure and lesions of the circumflex artery and its branches were excluded, as well as patients with significant comorbidities that were inappropriate for randomization because we selected them for OPCAB procedures.

RESULTS

Hospital mortality was 2.5%, three patients (3.7%) in group I (on-pump) and one patient (1.2%) in group II (off-pump) (ns). The number of grafts per patients in group I was 1.81 +/- 0.6, and 1.77 +/- 0.68 in group II (p = 0.833). There was no difference in the total operation time 205.10 +/- 54.30 minutes in group I and 189.50 +/- 55.44 in group II (ns). Six patients (7.5%) had myocardial infarction in group I and three (3.7%) in group II (ns). Bleeding in the postoperative period was 680.50 +/- 434.1 mL in the on-pump group and 678.6 +/- 357.0 mL in the off-pump group (ns). Three patients (3.7%) presented transient neurologic dysfunction in group I and six patients (7.5%) in group II (ns). Intensive care stay was 2.4 +/- 1.0 days in the CABG and 2.3 +/- 0.98 days in the OPCAB group (ns).

CONCLUSIONS

We did not find any statistical difference in hospital mortality and morbidity using on-pump or off-pump techniques for low-risk patients.

A comparison of short- and long-term outcomes after off-pump and on-pump coronary artery bypass graft surgery with sternotomy

OBJECTIVES

This study was designed to compare in-hospital mortality and complications and three-year mortality and revascularization for off-pump and on-pump coronary artery bypass graft (CABG) surgery after adjusting for patient risk.

BACKGROUND

The use of off-pump CABG surgery has increased tremendously in recent years, but little is known about its long-term outcomes relative to on-pump CABG surgery, and most studies have been very small.

METHODS

Short- and long-term outcomes (inpatient mortality and complications, three-year risk-adjusted mortality, and mortality/revascularization) were explored for patients who underwent off-pump CABG surgery (9135 patients) and on-pump CABG surgery (59044 patients) with median sternotomy from 1997 to 2000 in the state of New York.

RESULTS

Risk-adjusted inpatient mortality was 2.02% for off-pump versus 2.16% for on-pump (p = 0.390). Off-pump patients had lower rates of perioperative stroke (1.6% vs. 2.0%, p = 0.003) and bleeding requiring reoperation (1.6% vs. 2.2%, p < 0.001) and higher rates of gastrointestinal bleeding, perforation, or infarction (1.2% vs. 0.9%, p = 0.003). Off-pump patients had lower postoperative lengths of stay (median 5 days vs. 6 days, p < 0.001). On-pump patients had higher three-year survival (adjusted risk ratio [RR] =1.086, p = 0.045) and higher freedom from death or revascularization (adjusted RR = 1.232, p < 0.001). When analyses were limited to 1999 to 2000, the two-year adjusted hazard ratio for survival was not significant (adjusted RR = 0.99, p = 0.81).

CONCLUSIONS

On-pump patients experience better long-term survival and freedom from revascularization than off-pump patients. However, the survival benefit from on-pump procedures was no longer present in the last two years of the study.

A randomized comparison of off-pump and on-pump multivessel coronary-artery bypass surgery

BACKGROUND

The effect of the use of coronary-artery bypass surgery without cardiopulmonary bypass and cardiac arrest ("off pump") on graft patency remains uncertain. We undertook a prospective, randomized, controlled study to compare graft-patency rates and clinical outcomes in off-pump surgery with conventional, "on-pump" surgery.

METHODS

We randomly assigned 50 patients to undergo on-pump coronary-artery bypass grafting and 54 to undergo off-pump surgery. Surgical and anesthetic techniques were standardized for both groups. Clinical outcomes and troponin T levels were measured. Three months later, the patients underwent coronary angiography, including quantitative analysis.

RESULTS

The mean age of the patients was 63 years, and 87 percent were men. The on-pump group received a mean of 3.4 grafts, and the off-pump group 3.1 (P=0.41). There were no deaths. There was no significant difference in the median postoperative length of stay between the two groups (seven days in each group). The area under the curve of troponin T levels was higher during the first 72 hours in the on-pump group than in the off-pump group (30.96 hr x microg per liter vs. 19.33 hr x microg per liter, P=0.02). At three months, 127 of 130 grafts were patent in the on-pump group (98 percent), as compared with 114 of 130 in the off-pump group (88 percent, P=0.002). The patency rate was higher for all graft territories in the on-pump group than in the off-pump group.

CONCLUSIONS

In this randomized study, off-pump coronary surgery was as safe as on-pump surgery and caused less myocardial damage. However, the graft-patency rate was lower at three months in the off-pump group than in the on-pump group, and this difference has implications with respect to the long-term outcome.

Cecilie Greig memorial lecture 2002. Myocardial protection: an expanding or contracting discipline?

For the past thirty years cardiac surgeons have had a unique opportunity to study the consequences of myocardial ischemia and reperfusion. With the advent of an ability to intervene in acute myocardial syndromes, cardiologists have vigorously joined that effort as have fundamental scientists. Exogenous myocardial protective strategies have emerged as have novel strategies that take advantage of endogenous mechanisms of myocardial protection. As a consequence of improved myocardial protection, operative mortality and morbidity, in particular the low output syndrome, have diminished. However, despite important increases in the knowledge base referable to myocardial ischemia and reperfusion, major advances in myocardial protection have slowed in the past several years. This article explores potential untapped options for augmenting myocardial protection and focuses on the potential adverse interactions between cardiopulmonary bypass and myocardial protection as a prime target for future investigations leading to improved myocardial management during heart operations.

Deep pericardial stitch enables hemodynamically stable exposure of beating heart

The use of a deep pericardial stitch to obtain optimal exposure for precise distal anastomoses was assessed in 51 patients (mean age, 56.5 +/- 9.1 years) undergoing off-pump coronary artery bypass grafting. Hemodynamic data were recorded after sternotomy, before, and after each of the 120 distal anastomosis. Most hemodynamic parameters did not change throughout the procedures. During exposure of the circumflex artery, there were significant decreases in systolic arterial pressure from 106.0 +/- 15.5 to 87.7 +/- 13.6 mm Hg, mean systemic arterial pressure from 83.9 +/- 11.7 to 68.5 +/- 17.0 mm Hg, stroke volume from 68.5 +/- 23.3 to 50.5 +/- 18.3 mL, and stroke index from 34.4 +/- 11.5 to 24.3 +/- 8.7 mL x m(-2). Cardiac function was not affected when other coronary arteries were bypassed. On completion of all anastomoses, hemodynamics returned to baseline status. It was concluded that the deep pericardial stitch enabled stable and safe exposure of the heart for off-pump coronary artery grafting.

Off-pump coronary surgery: how do the anesthetic considerations differ?

In recent years, there has been much interest in performing coronary artery bypass graft (CABG) surgery without the aid of cardiopulmonary bypass (CPB). Initial efforts focused on "minimally invasive" direct coronary artery bypass, wherein the left anterior descending artery is bypassed with an in situ left internal mammary artery graft through a small left anterior thoracotomy. A more widely adopted approach however, is off-pump CABG (OPCAB), in which CABG surgery is performed on one or more vessels through the usual median sternotomy approach without the aid of CPB. This article reviews the differences in the anesthetic considerations of OPCAB compared to conventional CABG using CPB.

Early and midterm clinical outcome in patients with severe left ventricular dysfunction undergoing coronary artery surgery

BACKGROUND

Patients presenting with severe left ventricular (LV) dysfunction undergoing coronary artery surgery are at increased risk of perioperative morbidity and mortality. The present study investigated early and midterm outcomes in a consecutive series of patients with severe LV dysfunction undergoing coronary surgery at our institution.

METHODS

Data on 5,195 consecutive patients undergoing coronary artery bypass grafting (CABG) alone (in-hospital mortality 1.35%) from April 1996 to August 2002 were prospectively recorded in the Patient Analysis and Tracking System. Two hundred and fifty patients (median age 65 years [interquartile range, 57 to 70]) with preoperative left ventricular ejection fraction less than 30% (74 off pump; 29.6%) were identified and early and midterm clinical outcomes analyzed. Propensity scores were used to take account of the imbalance in the distribution of prognostic factors between the on-pump and off-pump groups.

RESULTS

Patients undergoing on-pump surgery were less likely to have current congestive heart failure, insulin-dependent diabetes, a history of hypertension, have had gastrointestinal tract surgery or an ulcer, or unstable angina. They had on average lower Parsonnet scores and New York Heart Association and Canadian Cardiovascular Score ratings. However they were more likely to have more extensive coronary artery heart disease and to require more grafts than those undergoing off-pump surgery. After adjustment for consultant team and propensity scores no differences between groups with regard to in-hospital mortality and morbidity were found. The only in-hospital outcome to show a significant difference after adjustment was the need for intraoperative inotropic support, which was higher in the on-pump group (odds ratio 5.1; 95% confidence interval 2.55 to 10.2; p < 0.001)). The median follow-up times for the on- and off-pump groups were 3.4 years and 1.4 years respectively. Three-year survival was higher with on-pump surgery (87% on-pump versus 73% off-pump) but this difference did not reach statistical significance after adjustment for prognostic variables (hazard ratio 0.54, 95% confidence interval 0.22 to 1.26, p = 0.16).

CONCLUSIONS

In-hospital mortality and morbidity in patients presenting with severe LV dysfunction is low with comparable results with both on- and off-pump coronary artery surgery. Midterm clinical outcome is encouraging and seems to justify surgical revascularization for this high-risk group of patients.

Microvascular Inflammatory Response in Cardiac Surgery

Cardiac surgical procedures, with or without cardiopulmonary bypass, elicit a systemic inflammatory response in patients that induces the elaboration of multiple cytokines, chemokines, adhesion molecules, and destructive enzymes. This inflammatory reaction involves multiple interdependent and redundant cell types and humoral cascades, which allows for amplification and positive feedback at numerous steps. This systemic inflammatory response ultimately results in a broad spectrum of clinical manifestations, with multiple organ failure being the most severe form. Investigative efforts have focused on understanding the mechanism of this systemic inflammatory response syndrome in order to develop potential therapeutic targets to inhibit it, thereby possibly decreasing postoperative morbidity and mortality. Multiple therapeutic methods have been investigated, including pharmacologic inhibitors and modifications of surgical technique and the cardiopulmonary bypass circuit. Although studies have demonstrated that the use of these therapies in experimental and clinical settings has attenuated the systemic inflammatory response, they have failed to conclusively show clinical benefit from these therapies. These therapies may be too specific to minimize the deleterious effects of a systemic inflammatory response that results from the activation of multiple, interdependent, and redundant inflammatory cascades and cell types. Hence, further studies that investigate the molecular and cellular events underlying the systemic inflammatory response syndrome and the resultant effects of anti-inflammatory therapies are warranted to ultimately achieve improvements in clinical outcome after cardiac surgical procedures.

Coronary occlusion using bi-directionally stretched elastic sutures during off-pump coronary artery bypass grafting

OBJECTIVE

Off-pump coronary artery bypass grafting may be partly invasive, particularly to the coronary endothelium that is snared. Efficacy of a simple technique to occlude a coronary artery with elastic sutures bi-directionally stretched just beneath the artery was evaluated.

METHODS

Test subjects were eighteen adult mongrel dogs weighing 20-30 kg. After systemic heparinization (150 U/kg), the mid-left anterior descending artery (mid-LAD) was exposed with a stabilizer applied and snared using non-elastic sutures (n = 6) or elastic sutures (n = 6), or occluded with elastic sutures bi-directionally stretched (n = 6). The left internal thoracic artery (LITA) was anastomosed to the mid-LAD with humidified gas insufflation. After completion of the anastomosis, the mid-LAD was observed endoscopically through the LITA. The coronary endothelium was also observed by a scanning electron microscope (SEM) after perfusion fixation.

RESULTS

Bleeding at the anastomotic site with the coronary artery occluded by bi-directionally stretched elastic sutures was observed. However, all anastomoses were done successfully with the aid of humidified gas insufflation. Coronary endoscope showed that the lumens snared with non-elastic sutures were collapsed with folds and often with clots. Coronary arteries snared with elastic sutures appeared similar to the arteries snared with non-elastic sutures endoscopically, but with less clots. In the case of coronary occlusion with bi-directionally stretched elastic sutures, the lumens were occluded in a flattened linear fashion without clots. SEM showed endothelial injuries with blood cells deposited when non-elastic sutures were used. When elastic sutures were used for snaring, endothelial injuries were ameliorated with less blood cells deposited, which were further decreased when elastic sutures were bi-directionally stretched.

CONCLUSION

The coronary artery can be effectively occluded by bi-directionally stretched elastic sutures with minimal endothelial damage.

Off-pump versus on-pump coronary artery bypass: meta-analysis of currently available randomized trials

BACKGROUND

Off-pump coronary artery bypass (OPCAB) challenges the conventional on-pump coronary artery bypass grafting (CABG) as the standard of surgical therapy for coronary disease. The aim of this study is to assess the differences in clinical outcomes between CABG and OPCAB by meta-analysis of data published in randomized trials.

METHODS

A literature search (Medline, Pubmed, Cochrane Controlled Trials Register, and the Cochrane Medical Editors Trial Amnesty of unpublished clinical trials) was done for the period starting from January 1990 until May 2002 and was supplemented with a manual bibliographic review for all peer-reviewed English language publications. A systematic overview (meta-analysis) of the randomized trials was done to define the risk of the composite end point (death, stroke, or myocardial infarction) in CABG versus OPCAB.

RESULTS

A literature search yielded nine comparable randomized studies, for a total of 1090 patients, of whom 558 and 532 were randomly assigned to CABG and OPCAB, respectively. Meta-analysis of these studies showed a trend, albeit not statistically significant, toward reduction in the risk of the composite end point for patients who had OPCAB (odds ratio 0.48; 95% confidence interval 0.21 to 1.09; p = 0.08).

CONCLUSIONS

Cumulative analysis of the few prospective randomized studies currently available found a potential clinical benefit of OPCAB, indicating that the avoidance of extracorporeal circulation might result in improved clinical outcomes. Further evidence, however, from large randomized trials is needed to assess potential advantages of OPCAB in terms of early outcomes.

Platelet function after coronary artery bypass grafting: is there a procoagulant activity after off-pump compared with on-pump surgery?

OBJECTIVE

After off-pump coronary artery bypass (OPCAB) haemostasis might be better preserved compared with on-pump coronary artery bypass grafting (CABG). The aim of this study was to investigate whether this possibly better preserved haemostasis results in a procoagulant activity of the platelets.

DESIGN

Thirty patients were studied prospectively, 15 undergoing on-pump CABG and 15 undergoing OPCAB. Platelet function was evaluated four times within the first 24 h: preoperatively, postoperatively, 4 h and 1 day after surgery with a bedside whole blood clotting test.

RESULTS

A significant increase of platelet-activating-factor-induced platelet aggregation was observed postoperatively after OPCAB (p < 0.01). Only two patients did not reach preoperative values within 1 day postoperatively and four patients had a more than twofold increase. Platelet aggregation immediately after on-pump CABG was reduced to near half of preoperative values, but within 1 day postoperatively normal platelet aggregation was regained in half of the patients.

CONCLUSION

This study has mainly indicated that platelets after OPCAB were more easily activated in the early postoperative period. After CABG with cardiopulmonary bypass we found a temporary platelet dysfunction which seemed to be overcome within the first postoperative day.

Off-pump coronary artery bypass grafting provides complete revascularization with reduced myocardial injury, transfusion requirements, and length of stay: a prospective randomized comparison of two hundred unselected patients undergoing off-pump versus conventional coronary artery bypass grafting

OBJECTIVE

Retrospective comparisons of selected patients undergoing off-pump versus conventional on-pump coronary artery bypass grafting have yielded inconsistent results and raised concerns about completeness of revascularization in off-pump coronary artery bypass grafting.

METHODS

Two hundred unselected patients referred for elective primary coronary artery bypass grafting were randomly assigned to undergo off-pump coronary artery bypass grafting with an Octopus tissue stabilizer (Medtronic, Inc, Minneapolis, Minn) or conventional coronary artery bypass grafting with cardiopulmonary bypass by a single surgeon. Revascularization intent determined before random assignment was compared with the revascularization performed. All management followed strict, unbiased, criteria-driven protocols. Patients and nonoperative care providers were blinded to surgical group.

RESULTS

Baseline characteristics were similar. The number of grafts performed per patient (mean +/- SD 3.39 +/- 1.04 for off-pump coronary artery bypass grafting, 3.40 +/- 1.08 for conventional coronary artery bypass grafting) and the index of completeness of revascularization (number of grafts performed/number of grafts intended, 1.00 +/- 0.18 for off-pump coronary artery bypass grafting, 1.01 +/- 0.09 for conventional coronary artery bypass grafting) were similar. Likewise, the index of completeness of revascularization was similar between groups for the lateral wall. Combined hospital and 30-day mortalities and stroke rates were similar. Postoperative myocardial serum enzyme measures were significantly lower after off-pump coronary artery bypass grafting, suggesting less myocardial injury. Adjusted postoperative thromboelastogram indices, fibrinogen, international normalized ratio, and platelet levels all showed significantly less coagulopathy after off-pump coronary artery bypass grafting. Patients undergoing off-pump coronary artery bypass grafting received fewer units of blood, were more likely to avoid transfusion altogether, and had a higher hematocrit at discharge. Cardiopulmonary bypass was an independent predictor of transfusion (odds ratio 2.42, P =.0073) by multivariate analysis. More patients undergoing off-pump coronary artery bypass grafting were extubated in the operating room and within 4 hours. Postoperative length of stay (in days) was shorter for off-pump coronary artery bypass grafting (5.1 +/- 6.5 for off-pump coronary artery bypass grafting, 6.1 +/- 8.2 for conventional coronary artery bypass grafting, P =.005 by Wilcoxon test). One patient (in the conventional coronary artery bypass grafting group) required angioplasty for graft closure within 30 days.

CONCLUSIONS

When compared with conventional coronary artery bypass grafting with cardiopulmonary bypass, off-pump coronary artery bypass grafting achieved similar completeness of revascularization, similar in-hospital and 30-day outcomes, shorter length of stay, reduced transfusion requirement, and less myocardial injury.

Aortic stent-grafting: successful introduction into the combined procedure for coronary artery bypass grafting and aortic aneurysm repair

OBJECTIVES

Coronary artery bypass grafting (CABG) and combined stent-grafting (SG) were evaluated to reduce morbidity and mortality of patients with descending or infrarenal aortic aneurysm.

METHODS

CABG and SG (thoracic n=6, infrarenal n=36) were performed during the same hospitalization in 42 patients (mean age of 73+/-14 years). In 29 patients (mean Euroscore: 9), SG was performed under local anesthesia 9+/-3 days after coronary surgery (simultaneous) and in 13 patients (mean Euroscore: 7) during the same anesthesia (synchronous). In the latter group, 11 out of 13 patients underwent off-pump CABG. All aneurysms were treated by implantation of commercially available self-expanding grafts.

RESULTS

CABG was successful in all, but one patient with left internal mammary artery hypoperfusion syndrome, requiring an additional distal saphenous graft to the left anterior descending coronary artery. SG was uneventful in 98% (41/42 patients). Postoperative computerized tomography showed incomplete sealing in seven patients (17%), but only the two attachment endoleaks had to be treated by one proximal and one distal SG extension. Overall hospital stay for the synchronous repair was 12.5+/-6 days and that of the simultaneous group 17.5+/-7 days. Thirty-day mortality was 5% (2/42) as one patient of the simultaneous group experienced a lethal cerebral embolism during SG and one patient of the synchronous group developed an untreatable infection. In the follow-up of 4 years, there were two vascular reinterventions but no additional procedure-related morbidity or mortality.

CONCLUSIONS

This experience shows that combined CABG and SG of thoracic or infrarenal aortic aneurysm is a safe and less-invasive alternative to the open graft repair, especially in the older patients or patients with severe comorbidities.

Effects of off-pump coronary artery bypass grafting on patient outcome

BACKGROUND

Cardiopulmonary bypass (CPB) is associated with postoperative myocardial stunning, hypothermia, formation of microemboli, and systemic inflammatory response syndrome, all of which may prolong recovery from coronary artery bypass grafting (CABG) surgery. This study sought to compare outcomes in patients undergoing CABG off pump versus on pump.

METHODS

Outcomes, including mortality and several morbidities, were reviewed in 1,623 on-pump patients and 683 off-pump patients. Morbidities assessed included postoperative bleeding, incidence of multiorgan dysfunction, and neurologic complications. Chi-square and t-test analysis were used to determine statistical significance.

RESULTS

Mortality was 42% lower in the off-pump group than the on-pump group. Both critical care and total hospital length of stay were significantly shorter in the off-pump group. The incidence of postoperative bleeding requiring transfusion or a return to the operating room was reduced by 29% in the off-pump group and the incidence of multiorgan dysfunction was reduced by 31%. The off-pump patients also presented a significantly lower incidence of cerebral vascular accidents and seizures than on-pump patients.

CONCLUSIONS

We conclude that there is an association between improved patient outcome and off-pump CABG surgery. The outcomes of this study show a statistically significant decrease in mortality, critical care length of stay, total hospital stay, incidence of bleeding requiring transfusion or return to the operating room, amount of blood transfused, incidence of multiorgan dysfunction, cerebral vascular accidents, and seizures in off-pump patients when compared with on-pump patients. Such results support the use of myocardial revascularization off pump as an alternative to CABG surgery on pump. CABG surgery off pump may allow a better postoperative clinical course in patients who are candidates for the procedure.

A comparison of on-pump and off-pump coronary bypass surgery in low-risk patients

BACKGROUND

The performance of coronary bypass surgery without cardiopulmonary bypass ("off pump") may reduce perioperative morbidity and costs, but it is uncertain whether the outcome is similar to that involving the use of cardiopulmonary bypass ("on pump").

METHODS

In a multicenter, randomized trial, we randomly assigned 139 patients with predominantly single- or double-vessel coronary disease to on-pump surgery and 142 to off-pump surgery. Cardiac outcome and cost effectiveness were determined one year after surgery. The uncertainty surrounding the cost-effectiveness ratio (cost differences per quality-adjusted year of life gained) was addressed by bootstrapping.

RESULTS

At one year, the rate of freedom from death, stroke, myocardial infarction, and coronary reintervention was 90.6 percent after on-pump surgery and 88.0 percent after off-pump surgery (absolute difference, 2.6 percent; 95 percent confidence interval, - 4.6 to 9.8). Graft patency in a randomized subgroup of patients was 93 percent after on-pump surgery and 91 percent after off-pump surgery (absolute difference, 2.0 percent; 95 percent confidence interval, - 6.5 to 10.4). On-pump surgery was associated with $1,839 in additional direct costs per patient ($14,908 vs. $13,069--a difference of 14.1 percent) and an increase in quality-adjusted years of life of 0.83 as compared with 0.82 (difference, 0.01 year; 95 percent confidence interval, - 0.03 to 0.04). Off-pump surgery was more cost effective than on-pump surgery in 95 percent of bootstrap estimates.

CONCLUSIONS

In low-risk patients, there was no difference in cardiac outcome at one year between those who underwent on-pump bypass surgery and those who underwent off-pump surgery. Off-pump surgery was more cost effective.

Off-pump total arterial myocardial revascularization according to the right Y-graft configuration

OBJECTIVES

The aims of this study were as follows: 1) to evaluate the early outcome of the off-pump total arterial myocardial revascularization according to the right y-graft (lambda-graft) configuration and 2) to compare baseline flow and maximum flow between patients undergoing on-pump and off-pump right y-graft (RYG) construction.

METHODS

Between December 1998 and January 2001, 47 patients (Group I) and 20 patients (Group II) with three vessel disease underwent on-pump and off-pump coronary artery bypass graft (CABG) respectively according to the RYG configuration. The mean age was 55.5 +/- 4.7 years and 55 +/- 6.4 years in Groups I and II, respectively. The RYG was constructed employing both internal mammary arteries (IMAs) only, in 21 and 8 patients in Groups I and II, respectively, presenting proximal-middle third stenosis of the left anterior descending artery (LAD) and right coronary artery (RCA). The modified RYG configuration employing both IMAs and radial artery (RA) was performed in 26 and 12 patients in Groups I and II, respectively, presenting middle-distal third stenosis of the LAD and distal stenosis of the RCA or posterior descending artery stenosis. Postoperatively all patients underwent transthoracic echo color-Doppler (TTECD) contrast enhanced (by Levovist) before and after adenosine provocative testat one week and three months after operation.

RESULTS

There were no hospital deaths. The mean mechanical ventilation was significantly different in Group I versus Group II patients, 18 +/- 4.4 hours versus 13 +/- 5.7 hours, respectively (p = 0.041). The mean intensive care unit stay was 1.5 +/- 0.6 days in Group I and 1 +/- 0.4 days in Group II (p = 0.033). There were no differences between Groups I and II regarding the IMA diameter, mean velocity, and mean flow. At follow-up time, 6 +/- 2.4 months after the surgical procedure, all patients were alive and free of angina. The coronary flow reserve (CFR) at LIMA main stem was significantly higher at three months when compared to the values at one week after the surgical procedure within the same group, (LIMA)CFR (three months) = 2.37 +/- 0.6 versus (LIMA)CFR (one week) = 2.07 +/- 0.4 (p = 0.005) in Group I and (LIMA)CFR (three months) = 2.4 +/- 0.4 versus (LIMA)CFR (one week) = 2.06 +/- 0.3 (p = 0.004) in Group II. Similarly, the CFR at RIMA main stem were significantly higher at three months when compared to the values at one week after the surgical procedure: (RIMA)CFR (three months) = 2.47 +/- 0.7 versus (RIMA)CFR (one week) = 2.1 +/- 0.5 (p = 0.004) in Group I and (RIMA)CFR (three months) = 2.48 +/- 0.5 versus (RIMA)CFR (one week) = 2.08 +/- 0.4 (p = 0.008) in Group II.

CONCLUSION

The flow dynamic data, almost identical between patients undergoing off-pump and on-pump total arterial myocardial revascularization (TAMR) according to the RYG configuration, demonstrate that this technique can be applied with excellent results without the employment of cardiopulmonary bypass in selected coronary artery disease patients.

Off-pump coronary artery bypass grafting: not a flash in the pan

During the past decade, technical improvements have made off-pump coronary artery bypass operations a routine procedure. During this time, off-pump coronary artery bypass has been audited against conventional techniques by many observational, case-matched, and prospective randomized studies. There is evidence in the literature suggesting that off-pump coronary artery bypass operations reduce postoperative morbidity, organ dysfunction, and costs, without compromising midterm outcome compared with conventional coronary operations. The available evidence also supports the view that high-risk patients might benefit the most from revascularization on the beating heart. High quality follow-up data are still needed to assess the impact of off-pump coronary artery bypass operations on long-term clinical outcome.

Effect of off-pump coronary surgery with right ventricular assist device on organ function and inflammatory response: a randomized controlled trial

BACKGROUND

Right ventricular assist devices (RVADs) have been proposed to improve exposure of the coronary arteries in off-pump surgery. In this study we investigated the impact of the A-Med RVAD on inflammatory response and organ function in patients undergoing coronary artery bypass grafting.

METHODS

Sixty patients were prospectively randomized to conventional surgery with cardiopulmonary bypass (CPB) and cardioplegic arrest, beating heart surgery (off-pump), or beating heart surgery with the RVAD. Serial blood samples were collected postoperatively, for analysis of inflammatory markers, troponin I, protein S100, and free hemoglobin. Renal tubular function was assessed by measuring urine N-acetyl-glucosaminidase activity.

RESULTS

No hospital deaths or major postoperative complications occurred in the study population. Interleukin-6, interleukin-8, C3a, and troponin I levels after surgery were significantly higher in the CPB group compared with the off-pump and RVAD groups. Free hemoglobin levels immediately after the operation, peak and total S100 levels, and N-acetyl-glucosaminidase activity were also significantly higher in the CPB group.

CONCLUSIONS

Off-pump coronary revascularization, with or without RVAD, reduces inflammatory response, myocardial, neurologic, and renal injury, and decreases hemolysis when compared with conventional surgery with CPB and cardioplegic arrest.

Comparison of off-pump versus conventional coronary revascularization

Between May 1999 and August 2001, 231 patients underwent off-pump coronary bypass, of whom 171 required revascularization of the anterior vessels of the heart. They were compared with a group matched for age, sex, and risk factors undergoing revascularization of the same group of vessels under cardiopulmonary bypass. Mortality was comparable in both groups but the incidence of cerebrovascular accident, respiratory insufficiency, and renal failure was less in the off-pump group. Postoperative drainage and blood transfusion requirements were significantly less in the off-pump group. Intensive care and hospital stay were shorter in the off-pump patients. A considerable number of patients are potential candidates for off-pump coronary bypass, the only contraindication being technical limitations. Follow-up at 6 to 24 months indicates that off-pump coronary bypass can be performed safely with a decrease in morbidity and more rapid return to normal lifestyle.

Effect of off-pump coronary artery bypass grafting on risk-adjusted and cumulative sum failure outcomes after coronary artery surgery

BACKGROUND AND AIM

We have shown that cumulative sum (CUSUM) failure analysis may be more sensitive than standard statistical methods in detecting a cluster of adverse patient outcomes after cardiac surgical procedures. We therefore applied CUSUM, as well as standard statistical techniques, to analyze a surgeon's experience with off-pump coronary artery bypass grafting (OPCAB) and on-pump procedures to determine whether the two techniques have similar or different outcomes.

METHODS

In 320 patients undergoing nonemergent, first time coronary artery bypass grafting, preoperative patient characteristics, rates of mortality and major complications, and ICU and hospital lengths of stay were compared between the on-pump and OPCAB cohorts using Fisher's exact tests and Wilcoxon two sample tests. Predicted mortality and length of stay were determined using previously validated models of the Cardiac Care Network of Ontario. Observed versus expected ratios of both variables were calculated for the two types of procedures. Furthermore, CUSUM curves were constructed for the on-pump and OPCAB cohorts. A multivariable analysis of the predictors of hospital length of stay was also performed to determine whether the type of coronary artery bypass procedure had an independent impact on this variable.

RESULTS

The predicted mortality risk and predicted hospital length of stay were almost identical in the 208 on-pump patients (2.2 +/- 3.9%; 8.2 +/- 2.5 days) and the 112 OPCAB patients (2.0 +/- 2.2%; 7.8 +/- 2.1 days). The incidence of hospital mortality and postoperative stroke were 2.9% and 2.4% in on-pump patients versus zero in OPCAB patients (p = 0.09 and 0.17, respectively). Mechanical ventilation for greater than 48 hours was significantly less common in OPCAB (1.8%) than in on-pump patients (7.7%, p = 0.04). The rate of 10 major complications was 14.9% in on-pump versus 8.0% in OPCAB patients (p = 0.08). OPCAB patients experienced a hospital length of stay that was a median of 1.0 day shorter than on-pump patients (p = 0.01). The observed versus expected ratio for length of stay was 0.78 in OPCAB patients versus 0.95 in on-pump patients. On CUSUM analysis, the failure curve in OPCAB patients was negative and was flatter than that of on-pump patients throughout the duration of the study. Furthermore, OPCAB was an independent predictor of a reduced hospital length of stay on multivariable analysis.

CONCLUSIONS

OPCAB was associated with better outcomes than on-pump coronary artery bypass despite a similar predicted risk. This robust finding was documented on sensitive CUSUM analysis, using standard statistical techniques and on a multivariable analysis of the independent predictors of hospital length of stay.

[Off-pump beating heart coronary artery bypass. Technical points of view and surgical results]

A consecutive series of 746 patients undergoing heart beating myocardial revascularization was reviewed. An average of 2.30 grafts/patients was performed. The rate of mortality in the first 30 postoperative days was 0.28%. Two cases had to be terminated on-pump. We used the inotropic drugs in 0.6% of cases. The postoperative events were: atrial fibrillation (12.6%), myocardial infarction (0.3%). The rate of transfusion was 7.4%. The extubation was performed in the first 24 h postoperatively in 94.7% of cases. The majority of patients (91.3%) left the hospital in the first 8 d postoperatively. Off pump coronary artery bypass grafting gives good result for the most of the patients even for those with multiple vessel disease and high operating risk.

Acute effects of beating heart coronary surgery on left ventricular performance

BACKGROUND

The increasing use of off-pump bypass grafting (OPCABG), requires an evaluation of its effects on left ventricular (LV) performance.

METHODS

In 8 patients with multivessel coronary disease who were undergoing to off-pump coronary artery bypass grafting, LV performance was analyzed from the pressure-volume (P-V) plane by the conductance catheter technique. Measurements were performed at base line, after the exposure of the vessels, after the application of the stabilization system, and at the end of the procedure.

RESULTS

No significant changes in heart rate, LV end-systolic volume, LV end-diastolic pressure, mean pulmonary artery, and mean systemic blood pressure were observed in the various stages of the procedure. Cardiac index decreased during left anterior descending coronary artery grafting after application of the stabilizer with a concomitant decrease in LV end-diastolic volume, together with decreases in LV peak negative -dP/dt and increases in tau, indicating an impairment of LV relaxation but without a change in preload recruitable stroke work, indicating preserved LV contractile state. Exposure of posterior and lateral vessels induced a decrease in cardiac index and preload recruitable stroke work without a decrease in LV preload, indicating a decrease in LV contractile state together with a decrease in peak -dP/dt and increase in tau, indicating an impairment in LV relaxation

CONCLUSIONS

Off-pump coronary artery bypass grafting can be performed without decreasing LV performance. Major cardiac displacement like that used for posterior and lateral exposure induces acutely significant decrease in LV contractile state.

The evolution of training in off-pump coronary surgery in a single institution

BACKGROUND

This study analyses the development of off-pump coronary artery bypass (OPCAB) surgery training at a single institution, and compares the early and midterm clinical outcomes of OPCAB and conventional coronary artery bypass grafting (CABG) procedures performed by trainees with or without direct consultant cardiothoracic surgeon supervision.

METHODS

Analysis was undertaken on data prospectively recorded on a computer database (Patient Analysis and Tracking System). Of the 2,422 CABG operations performed between January 1999 and December 2001, 969 (40%) were carried out by trainees either off pump (422) or on pump (547).

RESULTS

Although the total number of CABG operations performed by trainees remained constant, there was a significant increase in the number of OPCAB operations during the study period compared with conventional CABG, as well as an increase in the average number of grafts per patient in the OPCAB group (both p < 0.05). Furthermore, a significant trend towards using two or more arterial conduits in the OPCAB group was observed in the study period. The number of OPCAB operations performed by trainees as independent operators without direct consultant supervision also increased significantly (p < 0.05). Early and midterm clinical outcomes were similar between patients operated by trainees on pump or off pump as independent operators versus under direct consultant supervision.

CONCLUSIONS

The significant increase in OPCAB operations performed by trainees as independent operators or under direct consultant supervision, as well as the increase in the number of grafts per patient and arterial conduits used for myocardial revascularization, demonstrate a progression of training in beating heart surgery for cardiothoracic trainees. Improvements in the techniques have made it safe to teach trainees off-pump multivessel coronary artery revascularization.

Effectiveness of coronary artery bypass grafting with or without cardiopulmonary bypass in overweight patients

BACKGROUND

Off-pump coronary artery bypass surgery has been demonstrated to reduce morbidity in elective patients. However, high-risk patients might benefit the most from this surgical procedure. Our goal was to investigate the effectiveness of on-pump and off-pump coronary artery bypass surgery on early clinical outcome in a consecutive series of overweight patients.

METHODS AND RESULTS

From April 1996 to April 2001, data on 4321 patients undergoing coronary surgery (mortality 1.4%) were prospectively entered into the Patient Analysis and Tracking System. Data were extracted for all patients with a body mass index > or =25 kg/m(2). A risk-adjusted analysis was performed to assess the effect of surgical technique in the whole overweight cohort. 2844 patients were identified (2261 male, median age 63, interquartile range 56 to 68). Patients undergoing on-pump surgery (2170, 76.3%) were less likely than those undergoing off-pump surgery to have hypercholesterolemia or left main stem disease and were, on average, less obese. However, they were more likely to have unstable angina and to have had a previous myocardial infarction, and they had more extensive coronary disease and received more grafts (all P<0.05). Unadjusted analyses, taking account only of consultant team, showed significant benefits of off-pump surgery in terms of hospital deaths, arrhythmias, inotropic use, use of intra-aortic balloon pump, blood loss, transfusion requirement, postoperative hemoglobin, chest infections, neurological complications, intensive care unit and hospital stay (all P<0.05). After adjustment for confounding prognostic factors, the benefits of off-pump surgery were still significant for death in hospital, transfusion requirement, postoperative hemoglobin, neurological complications, intensive care unit and hospital stay (ORs 0.35 to 0.79, P<0.05).

CONCLUSIONS

These results suggest that off-pump surgery is safe and effective and is associated with a reduced in-hospital mortality and morbidity in overweight patients when compared with conventional coronary surgery with cardiopulmonary bypass and cardioplegic arrest.

Improved outcomes in coronary artery bypass grafting with beating-heart techniques

OBJECTIVE

Although improved outcomes for selected patients by elimination of cardiopulmonary bypass have been demonstrated, a benefit for all patients undergoing coronary artery bypass grafting by all surgeons has yet to be definitively proved.

METHODS

We reviewed our experience with beating-heart surgery from its inception in January 1995 through December 2000. A total of 12,540 patients underwent isolated coronary artery bypass grafting, including 1915 procedures (15%) performed without cardiopulmonary bypass. Groups were compared by univariate analysis for preoperative risk factors and postoperative complications, and predicted risk was determined by the Society of Thoracic Surgeons risk algorithm.

RESULTS

There was a gradual increase in the percentage of coronary operations performed off pump, from 1.2% in 1995 to 34.1% in 2000. Individual surgeon adoption rates ranged from 1% to 96% by 2000. There was a decrease in mortality to 3.22%, compared with an overall observed mortality rate of 4.0% in the 5 years before beating-heart surgery (P =.0482). There was a significant difference in observed mortality between the off-pump and on-pump groups (1.9% vs 3.5%, P <.001), despite a higher mean predicted risk among the patients in the off-pump group (3.13% vs 2.8%, P <.004). Additionally, decreased morbidity in the off-pump group was evidenced by reduced needs for blood products (28.45% vs 54.65%, P =.0001), prolonged ventilation (5.83% vs 10.93%, P =.001), and reoperation for bleeding (2.41% vs 3.65%, P =.0237), and by shorter hospital stay (5.98 vs 7.32 days, P =.001).

CONCLUSIONS

Beating-heart surgery can be safely assimilated into a cardiac surgical practice, although adoption rates vary significantly among individual surgeons. Gradual integration can lead to improved outcomes in the total coronary artery bypass surgery population.