A multimodal approach to the prevention of postoperative stroke in patients undergoing coronary artery bypass surgery

Off-Pump Coronary Artery Bypass Grafting; is it Still Relevant?

Off-pump Coronary Artery Bypass Grafting (OPCAB) experienced a resurgence in the 1980s -2000s and developed steadily with improvement of the instrumentation and techniques. However questions about graft patency and long-term survival of OPCAB patients still exist. This review attempts to explore the current relevance of OPCAB.

Surgical strategies for severely atherosclerotic (porcelain) aorta during coronary artery bypass grafting

Porcelain aorta (PA) is an asymptomatic atherosclerotic disease, characterized by circumferential calcification throughout the whole perimeter of the aorta. It is seen in 2% to 9.3% of patients undergoing elective coronary artery bypass grafting (CABG) and makes manipulation of the ascending aorta impossible. It has been clearly shown that most emboli seen and detected during the CABG procedure occur during aortic cross-clamping and aortic side-clamping. Manipulation of porcelain or a severely atherosclerotic aorta increases the risk of perioperative stroke. The incidence of stroke after CABG is between 0.48% and 2.9%, and the risk is correlated with the extent and severity of the atherosclerotic disease. A conventional CABG procedure involves successive steps that include cannulation of the ascending aorta, application of a cross-clamp to the aorta, and partial clamping of the aorta to create the proximal anastomosis. Therefore in procedures that involve cannulation, clamping, or proximal anastomosis, and where aortic manipulation is inevitable, preassessment of the atherosclerotic aortic plaques is crucial. Although many surgeons still rely on intraoperative manual aortic palpation, this approach has very low sensitivity and underestimates the severity of the atherosclerotic illness. Imaging methods including preoperative computed tomography or intraoperative epiaortic ultrasonography enable modification of the surgical technique according to the severity of atherosclerosis. Various surgical techniques have been described to reduce the risk of atheroembolism that may lead to cerebrovascular events in patients with severely atherosclerotic ascending aorta. Anaortic or "no-touch" techniques that do not utilize aortic manipulation may significantly decrease the development of neurological complications by avoiding aortic maneuvers known to cause emboli. In cases where severe atherosclerotic disease or other factors preclude safe use of the ascending aorta, modifications in the surgical techniques, such as switching to different cannulation sites including the axillary/subclavian, femoral and innominate arteries, or using hypothermic ventricular fibrillation and in-situ pedicled arterial grafts, or performing proximal anastomoses at alternative anatomical locations will enable CABG operations to be performed safely with low morbidity and mortality rates in patients with porcelain aortas.

Prognostic role of carotid intima-media thickness in off-pump coronary artery bypass surgery

Carotid intima-media thickness (IMT) is a well-known predictor of adverse outcomes in the ischemic heart disease patients; however, evidence is lacking in patients undergoing off-pump coronary artery bypass surgery (OPCAB). Data from 407 patients who underwent OPCAB between April 2013 and August 2016 were retrospectively reviewed. A composite of cardiovascular morbidity endpoints was defined as the presence of stroke, acute myocardial infarction, new cardiac arrhythmia (newly developed atrial fibrillation, atrial flutter, or atrioventricular block), cardiovascular death, or cerebrovascular death within 30 days after surgery. Increased carotid IMT was defined as ≥0.9 mm on one or both sides. The incidence of a composite of cardiovascular morbidity endpoints was 24.0% in the normal IMT group (n = 221) and 34.4% in the increased IMT group (n = 186) (p = 0.021). Multivariable analysis revealed increased IMT (odds ratio 1.719, 95% confidence interval 1.108 to 2.666, p = 0.016) and preoperative renal replacement therapy (odds ratio 4.264, 95% confidence interval 1.679 to 10.829, p = 0.002) as independent predictors of a composite of cardiovascular morbidity endpoints. In patients undergoing OPCAB, preoperative assessment of carotid IMT may help predicting the development of a postoperative composite of cardiovascular morbidity endpoints.

Perioperative erythropoietin protects the CNS against ischemic lesions in patients after open heart surgery

AIM

The aim of this study was to establish erythropoietin as a protective factor against brain ischemia during open heart surgery.

METHODS

A total of 36 consecutive patients scheduled for revascularization heart surgery were included in the study. Of the patients 18 received 3 intravenous doses of recombinant human erythropoietin (rHuEpo, 24,000 IU) and 18 patients received a placebo. Magnetic resonance imaging (MRI) to detect new brain ischemic lesions was performed. Additionally, S100A, S100B, neuron-specific enolase A and B (NSE-A and B) and the concentration of antibodies against N‑methyl-D-aspartate receptors (NMDAR) to identify new neurological complications were determined.

RESULTS

Patients who received rHuEpo showed no postoperative ischemic changes in the brain on MRI images. In the control group 5 (27.8 %) new ischemic lesions were found. The NMDAR antibody concentration, S100A, S100B and NSE showed no significant differences between the groups for new cerebral ischemia. High levels of lactate before and after external aortic compression (p = 0.022 and p = 0.048, respectively) and duration of operation could predict new ischemic lesions (p = 0.009).

CONCLUSIONS

The addition of rHuEpo reduced the formation of lesions detectable by MRI in the brain and could be used clinically as neuroprotection in cardiac surgery.

Anastomotic devices in coronary artery surgery: it is about the anastomosis?

Excellent long-term graft patency remains the primary goal of any surgical coronary revascularization procedure, irrespective of how the operation itself is performed. Inter- and intra-surgeon variability in the surgical technique and in the subsequent quality of the anastomosis have the potential to significantly impact not only on graft patency but also, as a result, on patient outcomes. Anastomotic devices, proximal and distal, can facilitate the creation of rapid, reproducible, compliant anastomoses, on- or off-pump, in potentially difficult-to-access areas, often through minimal-access incisions, potentially with neuro-protective benefits, and can thus mitigate some of the hazards inherent in manually constructing anastomoses in technically challenging or suboptimal conditions. We review the three most commonly employed anastomotic devices in adult cardiac surgical practice today.

HEARTSTRING enabled no-touch proximal anastomosis for off-pump coronary artery bypass grafting: current evidence and technique

Surgical revascularization remains the standard of care for many patients. Off-pump coronary artery bypass grafting (OPCAB) without cardiopulmonary bypass (CPB) has evolved during the past 20 years, and as such can significantly reduce the occurrence of neurological complications. While avoiding the aortic cross-clamping required in conventional on-pump techniques, OPCAB results in a lower incidence of stroke. However, clamp-related risk of stroke remains if partial or side-biting clamps are applied for proximal anastomoses. Others and we have demonstrated that no-touch 'anaortic' approaches avoiding any clamping during off-pump procedures via complete in situ grafting result in significantly reduced stroke rates when compared with partial clamping. Therefore, OPCAB in situ grafting has been proposed as the 'standard of care' to reduce neurological complications. However, this technique may not be applicable to for every patient as the use of free grafts (arterial or venous) requiring proximal anastomosis is often still necessary to achieve complete revascularization. In these situations, proximal anastomosis can be performed without a partial clamp by using the HEARTSTRING device, and over the last few years, considerable evidence has arisen supporting the impact of HEARTSTRING-enabled anastomosis to significantly minimize atheroembolism and neurological complications when compared with partial- or side-bite clamping. This paper provides a systematic overview and technical information about the combination of OPCAB and clampless strategies using the HEARTSTRING for proximal anastomosis to reduce stroke to levels reported for percutaneous coronary intervention.

Monitoring brain oxygen saturation during awake off-pump coronary artery bypass

OBJECTIVE

To evaluate the changes in cerebral blood flow during awake off-pump coronary artery bypass grafting and compare with the changes during off-pump coronary artery bypass grafting under general anesthesia, using continuous monitoring of regional cerebral oxygen saturation.

METHODS

The study population comprised 3 groups of patients who had undergone off-pump coronary artery bypass grafting with thoracic epidural anesthesia, general anesthesia, or a combination of the two. Regional brain oxygen saturation, determined with a near-infrared oxygen monitor, and mean arterial pressure during surgery were calculated and compared among the 3 groups.

RESULTS

Patients who had undergone awake off-pump coronary artery bypass grafting with thoracic epidural anesthesia had a significantly higher cerebrovascular impairment ratio, and the EuroSCORE was high. No significant differences were observed among the 3 groups in terms of the relationship between mean arterial pressure during surgery and regional brain oxygen saturation. It is suggested that there were no differences in cerebral blood flow and mean arterial pressure changes among the 3 groups.

CONCLUSIONS

Awake off-pump coronary artery bypass grafting is a safe surgical technique for patients with history of cerebral infarction or impaired cerebral blood flow. Awake off-pump coronary artery bypass grafting is a less invasive procedure that allows efficient management of intraoperative cerebral blood flow, and can be equally effective as a percutaneous coronary intervention.

Clampless off-pump surgery reduces stroke in patients with left main disease

BACKGROUND

Surgical revascularization is the most appropriate therapy for patients with significant left main coronary-artery disease (LMD). An incidence of perioperative stroke remains an issue when compared to the early outcomes to percutaneous coronary intervention (PCI). This study evaluates the safety and impact of standardized "clampless" OPCAB techniques, composed of either complete in situ grafting or "clampless" device enabled techniques for stroke reduction in patients undergoing surgical revascularization for LMD.

METHODS

Between 1999 and 2009, 1031 patients with LMD underwent myocardial-revascularization at our institution. Of these, 507 patients underwent "clampless" OPCAB and 524 patients underwent conventional on-pump CABG (ONCABG). Data-collection was performed prospectively and a propensity-adjusted regression-analysis was applied to balance patient characteristics. LMD was defined as a stenosis >50% and endpoints were mortality, stroke, a cardiac-composite (including death, stroke and myocardial-infarction); a non-cardiac composite and complete-revascularization.

RESULTS

In OPCAB patients, the cardiac composite (3.0% vs. 7.8%; propensity-adjusted (PA)OR=0.27; CI95% 0.12-0.65; p=0.003) as well as the occurrence of stroke (0.4% vs. 2.9%; PAOR=0.04; CI95% 0.003-0.48; p=0.012) were significantly lower while the mortality-rate was well comparable between groups (1.8% vs. 2.5%; PAOR=0.44; CI95% 0.11-1.71; p=0.24). The non-cardiac composite was also significantly decreased after OPCAB (8.9% vs. 19.7%; PAOR=0.55; CI95% 0.34-0.89; p=0.014) and complete revascularization was achieved for similar proportions in both groups (95.1% vs. 93.7%; p=0.35).

CONCLUSIONS

This study shows the superiority of OPCAB for patients with LMD with regards to risk-adjusted outcomes other than mortality. A "clampless OPCAB strategy", effectively reduces stroke yielding similar early outcomes as PCI.

Aortic no-touch technique makes the difference in off-pump coronary artery bypass grafting

OBJECTIVES

Both off-pump surgery (OPCAB) and aortic no-touch technique reduce stroke after coronary artery bypass grafting (CABG). We evaluate the impact of partial aortic clamping (PC) versus a no-touch technique using either the HEARTSTRING system (HS) or total arterial revascularization (TAR) on the incidence of stroke.

METHODS

From 1999 [corrected] to 2009, 4314 patients underwent myocardial revascularization. Patients either underwent OPCAB (n = 2203) or conventional on-pump CABG (n = 2111). The OPCAB cohort was divided into 2 subgroups: patients requiring proximal anastomosis applying PC (n = 567) or a "no-touch" technique with the HS (n = 1365). Patients who received TAR (n = 271) served as a control group (gold-standard). Data collection was performed prospectively using a propensity score (PS)-adjusted regression analysis. End points were stroke, mortality, major adverse cardiac and cerebrovascular events (MACCE), and a noncardiac composite end point including respiratory failure, renal failure, and bleeding.

RESULTS

The mortality rate (1.6% vs 2.4%; propensity-adjusted odds ratio [PAOR] = 0.51; CI 95%, 0.26-0.99; P = .047), MACCE (7.9% vs 17.1%; PAOR = 0.67; CI 95%, 0.52-0.84; P = .001) including myocardial infarction (1.1% vs 2.2%; PAOR = 0.50; CI 95%, 0.26-0.98; P = .044) and stroke (1.1% vs 2.4%; PAOR = 0.35; CI 95%, 0.17-0.72; P = .005) as well as the noncardiac composite (PAOR = 0.46; CI 95%, 0.35-0.91; P < .001) were significantly lower for OPCAB when compared with on-pump CABG. In comparison with PC, OPCAB patients undergoing the HS approach had significantly lower frequencies of stroke (0.7% vs 2.3%; PAOR = 0.39; CI 95%, 0.16-0.90; P = .04) and MACCE (6.7% vs 10.8%; PAOR = 0.55; CI 95%, 0.38-0.79; P = .001), and these results were similar to those of the control group, who underwent no-touch TAR (stroke rate, 0.8%; MACCE, 7.9%).

CONCLUSIONS

Our results confirm that OPCAB is superior with regard to risk-adjusted outcomes. There is no difference in the stroke rate when comparing on-pump CABG versus applying partial aortic crossclamping in OPCAB. Whenever a proximal anastomosis is needed, a no-touch technique should be applied, that is, using the HS device.