Regional left ventricular systolic function in humans during off-pump coronary bypass surgery

Pharmacological preconditioning with intralipid in patients undergoing off-pump coronary artery bypass surgery

Aims and Objectives:

The objective of the study was to determine the preconditioning myocardial protective effects of intralipid (IL) in off-pump coronary artery bypass (OPCAB) surgery by measuring highly sensitive troponin T (hsTnT) and cardiac-specific creatine kinase (CK-MB) as markers of myocardial injury.

Materials and Methods:

Thirty patients, scheduled to undergo elective OPCAB surgery, were randomly assigned to the IL group (n = 15) or control (C) group (n = 15); the IL group received an infusion of 20% IL 2 ml/kg, 30 min prior to revascularization and the control group received an equivalent volume of normal saline. Serum levels of hsTnT and CK-MB were measured before surgery and at 6 h, 24 h, 48 h, and 72 h postoperatively. Also, intraoperative hemodynamic parameters, inotrope use, ventilatory hours, ICU stay, postoperative left ventricular ejection fraction, postoperative lipid profile, renal and hepatic function tests were measured.

Results:

The hsTnT values at the 24 h, 48 h, and 72 h in IL group were significantly lower as compared with the control group. The decline in plasma levels of CK-MB mirrored the hsTnT levels post revascularization at 24 h and 48 h in the IL group compared with the control group; however, at 72 h, level was comparable in both the groups. None of the treated patients had abnormal lipid metabolism, deranged renal, and hepatic function.

Conclusion:

The study revealed Intralipid as a safe pharmacological preconditioning agent for OPCAB surgeries which can reduce the postischemic myocardial injury indicated by the reduction in postischemic cardiac enzymes hsTnT and CK-MB.

Off-Pump Coronary Artery Bypass Surgery

Off-pump coronary artery bypass surgery has been adopted enthusiastically worldwide. However, despite more than 6 years’ experience and refinement, many surgeons use it only sporadically and some hardly at all. This reluctance persists despite support for the procedure because of the lack of properly designed risk models and/or randomized studies. Although it has not been overwhelmingly shown that off-pump surgery is superior to the conventional on-pump procedure, the technique has its place in our specialty. It has been shown to be better for noncritical end points in selected patients in the hands of selected surgeons. That there are differences in surgical skill among surgeons is something we all know but rarely discuss in public. Until now, disparities in skill have been most salient with uncommon and extraordinarily challenging operations. Perhaps the off-pump procedure should be regarded as the “challenging” aspect of coronary artery bypass surgery, and self-restraint may need to remain in force if we are to continue to achieve the highest level of clinical excellence.

Off-pump Coronary Artery Bypass is a Safe Option in Patients Presenting as Emergency

Introduction: The applicability of off-pump coronary-artery bypass (OPCAB) in patients who present as emergency remains controversial. Herein, we explore the efficacy and safety of OPCAB in patients who were indicated for emergency surgery. Materials and Methods: Between 2002 and 2007, a total of 282 patients underwent OPCAB, of which 68 were presented as emergency. This cohort (group A) was compared to 68 patients who had traditional on-pump coronary artery bypass grafting (CABG, group B) under emergency indications during the same period of time. Baseline demographics, intraoperative data and postoperative outcomes were analysed. Results: Preoperative demographics were comparable in both groups. Mortality during the first 30 days was comparable in both groups and no stroke occurred in the whole series. Patients in group A had significantly less pulmonary complications (4.4% vs 14.7%, P= 0.04), less ventilation time (30.3 ± 33.6 hours vs 41.5 ± 55.4 hours, P = 0.18) and were less likely to have prolonged ventilation, (19.1% vs 35.3%, P = 0.03). Similarly, OPCAB patients had less postoperative renal-failure/dysfunction (5.9% vs 8.8%, P = 0.51) and required less inotropic support (66.2% vs 88.2%, P = 0.002), bloodtransfusions (23% vs 86.8%, P <0.0001), and atrial- (17.6% vs 35.3%, P = 0.02) or ventricular-pacing (17.6% vs 41.2%, P = 0.002). Although the number of diseased vessels was comparable in both groups, patients in group A received less distal anastomoses. (2.78 ± 1.19 vs 3.41 ± 0.89, P = 0.002). Similarly, complete revascularisation was achieved less frequently in group A (76.5% vs 94.1%, P = 0.004). Conclusion: OPCAB strategy is a safe and efficient in emergency patients with reasonable good short-term postoperative outcomes. Keywords: Cardiac surgery, Coronary artery disease, Off-pump coronary-artery bypass

Acute Effect of Cerivastatin on Cardiac Regional Ischemia in a Rat Model Mimicking Off-Pump Coronary Surgery

BACKGROUND

Although the off-pump technique is becoming widely used in coronary bypass surgery, there has been no experimental rat heart model of regional reversible ischemia. The aims of this study were to investigate the optimal duration of coronary occlusion for making reversible ischemia and to examine whether cerivastatin increases myocardial tolerance against prolonged coronary occlusion.

METHODS

Study 1--Male Sprague-Dawley rats (350 to 450 g) underwent temporary occlusion of either left anterior descending artery (LAD; for 3, 5, 7.5, 10, 12.5, 15, or 20 min) or circumflex artery (CX; for 5, 10, or 15 min). Study 2--Rats were divided into two groups, control and cerivastatin groups, which had 0.1 mg/kg cerivastatin intravenously after anesthesia. LAD was occluded for 10, 15, or 20 minutes. In the both studies, hearts were stained to determine the area at risk (AR) and infarcted (IF) area 24 hours after reperfusion.

RESULTS

In LAD occlusion, IF/AR increased in a time dependent manner: 4.5 +/- 3.2%, 9.7 +/- 5.2%, 17.2 +/- 3.0%, 16.8 +/- 2.7%, 23.9 +/- 9.5% (p < 0.01 vs. 3 min), 62.4 +/- 2.9% (p < 0.0001), and 63.4 +/- 2.9% (p < 0.0001) at 3, 5, 7.5, 10, 12.5, 15, and 20 min, respectively. Also in CX, IF/AR increased with time: 14.3 +/- 2.3%, 25.9 +/- 2.1%, and 40.9 +/- 6.2% (p < 0.001 vs. 5 min) at 5, 10, and 15 min, respectively. Cerivastatin significantly reduced IF/AR at 15 minutes (43.7 +/- 6.2%) and at 20 minutes (44.6 +/- 5.3%) compared to control (62.4 +/- 2.9% and 60.6 +/- 2.5%, respectively, p < 0.05).

CONCLUSION

Cerivastatin increased myocardial tolerance after prolonged coronary occlusion over 10 minutes, which was considered to be the upper limit for creating a regional reversible ischemia in rats.

Intraoperative ischemia and long-term events after minimally invasive coronary surgery

BACKGROUND

Concern has been raised about the effects of prolonged left anterior descending (LAD) artery occlusion during minimally invasive direct coronary artery bypass graft surgery (MIDCABG). We sought to assess the impact of myocardial dysfunction during MIDCABG on long-term outcome and the protective role of collateral circulation on myocardial ischemia.

METHODS

Myocardial function was evaluated in 92 patients by intraoperative transesophageal echocardiography during MIDCABG.

RESULTS

Wall motion score index increased during LAD occlusion (p < 0.00l) and reverted after LAD reopening (p < 0.001 versus occlusion and p = not significant versus baseline). The change in wall motion score index (occlusion versus baseline) was higher in patients with multivessel disease (p < 0.05) and in patients with LAD Thrombolysis in Myocardial Infarction study classification flow grade 2 or less without collateral circulation (p < 0.05). Myocardial stunning was documented in 12 patients (13%). The 5-year adverse event rate (including death, myocardial infarction, and revascularization) was 12%. By multivariate Cox regression analysis, multivessel disease, but not perioperative ischemia or stunning, was the only predictor of event-free survival.

CONCLUSIONS

During MIDCABG anterior wall dysfunction is transient, with prompt recovery after completion of the anastamosis in most cases; myocardial stunning can be documented in a minority of patients. Flow either antegrade or retrograde in the LAD territory plays a protective role against the development of ischemia. Multivessel disease, but not perioperative ischemia or stunning, predicts long-term event-free survival.

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.

Proteasome inhibition ablates activation of NF-kappa B in myocardial reperfusion and reduces reperfusion injury

Both acute coronary occlusion and reperfusion of an infarct-related artery lead to significant myocardial cell death. Recent evidence has been presented that activation of the transcription factor nuclear factor-kappaB (NF-kappaB) plays a critical role in reperfusion injury. NF-kappaB is usually bound to its inhibitor, IkappaB, and classic activation of NF-kappaB occurs when the 20S proteasome degrades IkappaB that has been phosphorylated and ubiquitinated. In this study, activation of NF-kappaB was inhibited by systemic administration of a 20S proteasome inhibitor (PS-519) in a porcine model of myocardial reperfusion injury. The experimental protocol induced myocardial ischemia in the distribution of the left anterior descending coronary artery for 1 h with subsequent reperfusion for 3 h. A single systemic treatment with PS-519 reduced 20S proteasome activity; blocked activation of NF-kappaB induced by reperfusion; reduced creatine kinase, creatine kinase-muscle-brain fraction, and troponin I release from the myocardium; preserved regional myocardial function measured by segmental shortening; significantly reduced the size of myocardial infarction; and exhibited no acute toxicity. These data show that myocardial reperfusion injury can be inhibited by using proteasome inhibitors, which likely function through the inhibition of NF-kappaB activation.

Anesthesia for off-pump coronary artery bypass grafting

Off-pump coronary artery bypass presents special challenges for the anesthesiologist and surgeon, who must work closely together to provide optimal care. Displacement and immobilization of the heart for exposure of the coronary arteries, as well as occlusion of these vessels, can result in periods of significant hemodynamic instability. Appropriate preparation, guided therapy, and technical maneuvers can lessen such adverse hemodynamic impact. It is important for anesthesiologists to be aware of the special problems associated with this surgery, as well as the different therapies and maneuvers that can be useful in providing the best possible care. As surgeons develop greater expertise and better devices for the management of these patients, the number of coronary revascularizations without CPB is likely to increase.

Off-Pump Coronary Artery Bypass Surgery: Revival of an Old Technique

The ability to perform surgical procedures on the heart was one of the greatest accomplishments of the 20th century. What was once considered an impossible task has become a routine in daily clinical activity. The in troduction of extracorporeal circulation and myocardial protection strategies opened the doors to what was considered by most an insurmountable barrier— unhin dered access to the coronary circulation and intracar diac structures. In the United States, approximately 85% of coronary artery bypass graft procedures are performed with the use of cardiopulmonary bypass (CPB). CPB was and remains the gold standard for this type of cardiac surgical intervention. Over the years, investigators have struggled to find ways of lessening or eliminating the adverse physiologic effects of CPB. These efforts have focused on pharmacologic interven tion, monitoring procedures, blood gas management, and temperature management. Another way of avoid ing these effects is inherently obvious — eliminate the main source of the problem.

Impact of off-pump coronary artery surgery on myocardial performance and beta-adrenoceptor function

OBJECTIVE

To determine the hemodynamic changes during beating heart revascularization of the left anterior descending artery, the circumflex artery, and the right coronary artery as well as cardiovascular beta-adrenoceptor function before and after off-pump coronary artery bypass surgery.

DESIGN

Prospective study.

SETTING

University department of cardiothoracic anesthesia.

PARTICIPANTS

Twenty patients scheduled for off-pump coronary artery bypass surgery using the Octopus 2 stabilizer system.

INTERVENTIONS

Isoproterenol, 4 microg, was administered intravenously after induction of anesthesia and again after surgery to monitor cardiac beta-receptor function.

MEASUREMENTS AND MAIN RESULTS

The hemodynamic responses to isoproterenol and cardiovascular variables were monitored before, during, and after immobilization of the target coronary artery with catheters in the radial and pulmonary arteries. During surgery on the left anterior descending artery (n = 23), stroke volume and cardiac index decreased 17 mL (21%) and 400 mL (17%). During revascularization of the circumflex artery (n = 9), stroke volume and cardiac index decreased 19 mL (28%) and 300 mL (17%). During surgery on the posterior aspect of the heart (n = 13), stroke volume and cardiac index decreased 22 mL (29%) and 400 mL (17%). All the cardiovascular variables had returned to baseline values 5 minutes after releasing the heart. The hemodynamic responses to isoproterenol were equal before and after surgery.

CONCLUSION

This study provides evidence that the hemodynamic changes associated with off-pump surgery on the 3 major coronary arteries are similar and of short duration. No desensitization of cardiovascular beta-adrenoceptors was found. This finding is in contrast to the deterioration in beta-adrenoceptor function seen after surgery with cardiopulmonary bypass.