Ultrasonic evaluation of graft anastomoses during coronary artery bypass grafting without cardiopulmonary bypass

Performance of the graft-to-coronary anastomosis in coronary artery bypass grafting without cardiopulmonary bypass is more difficult than conventional coronary artery bypass grafting. We report a new method that uses high-frequency epicardial echocardiography to detect technical errors and inadequacies in graft anastomoses. This method improves the operative outcome and enables detection of septal perforator branches and deeply embedded coronary arteries during coronary artery bypass grafting without cardiopulmonary bypass.     

Reoperative coronary artery bypass grafting without cardiopulmonary bypass

Between October 1995 and Feburary 1997, 2 men and 4 women aged 53 to 75 years (mean, 66.3) underwent reoperative coronary artery bypass grafting without cardiopulmonary bypass. Isolated reoperative circumflex or intermediate artery bypass was performed through a left thoracotomy (n=2), reoperative bypass to the left anterior descending coronary aretery was performed through a median sternotomy (n=3), and bypass to the right coronary artery was performed through an upper median laparotomy (n=1). Single coronary bypass grafting utilizing arterial grafts (left internal thoracic artery: 3, right gastroepiploic artery: 3) was performed in all cases. There were no operative deaths. All cases required neither cathecolamine nor intraaortic balloon pumping). Peri/post operative blood transfusion was necessary in only one case. Postoperative coronary angiography revealed that the 6 arterial grafts were patent. Reoperative coronary artery bypass grafting without cardiopulmonary bypass can be performed with low perioperative morbidity and mortality, easy postoperative management, satisfactory graft patency, and good symptomatic improvement.     

Atrial fibrillation after coronary artery bypass grafting without cardiopulmonary bypass.

OBJECTIVE: Atrial fibrillation is the most common complication after heart surgery. It rarely has a fatal outcome but causes patient instability, prolongs hospital stay, or even is the reason for perioperative infarction. Although conventional coronary artery bypass grafting (CABG) with cardiopulmonary bypass has excellent short-term and long-term results, the number of coronary operations on a beating heart without cardiopulmonary bypass is still growing. To reduce surgical trauma, off-pump coronary artery bypass grafting via sternotomy (OPCABG) or minimally invasive direct vision coronary artery bypass grafting (MIDCABG) via small thoracotomy are performed. The aim of this study was to estimate the frequency of atrial fibrillation in patients after myocardial revascularization without cardiopulmonary bypass. METHODS: A retrospective analysis of 48 patients undergoing myocardial revascularization without cardiopulmonary bypass was performed. Twenty-four patients underwent OPCABG and 24 were operated using the MIDCABG technique. The incidence of cardiac arrhythmias was analyzed since operation to the fourth postoperative day. Each patient had continuous ECG monitoring with option of arrhythmia analysis during ICU stay. After discharge from ICU 24-h ECG monitor studies were carried out. Surface 12-lead ECG was accomplished once a day, and additionally each time symptoms of cardiac arrhythmia occurred. Risk factors of atrial fibrillation were estimated. RESULTS: Atrial fibrillation occurred in 25% of patients after MIDCABG, in 29% after OPCABG, and in 18% after CABG with cardiopulmonary bypass. This difference has no statistical significance. Risk factors and incidence of postoperative complications were comparable in all groups. CONCLUSIONS: Atrial fibrillation is a common complication after procedures of myocardial revascularization, performed with or without cardiopulmonary bypass. The occurrence is not dependent on the type of operation.     

Is coronary artery bypass grafting without cardiopulmonary bypass safe?

Summary Three hundred and fifty patients underwent coronary artery bypass surgery on a beating heart. This technique is easy to learn and is suitable in selected patients.     

Indications and problems of coronary artery bypass grafting without cardiopulmonary bypass

As an alternative method of myocardial protection and to obviate the inherent risks of cardiopulmonary bypass (CPB), we have been performing coronary artery bypass grafting (CABG) without CPB in carefully selected patients. Since the first such operation was successfully performed in Junuary 1995 on a patient with angina pectoris and lung cancer, four other patients have subsequently undergone this technique. This series of 5 patients, being 1 man and 4 women ranging in age from 68 to 80 years, is presented in this report. The reasons for the selection of this procedure were concomitant diseases including lung cancer, a calcified aorta, and myocardial infarction. The mean time of ischemia for each anastomosis was 15.3 ± 5.3min, and the maximum cardiac muscle creatine phosphokinase (CPK-MB) was less than 14 unit/l postoperatively. None of the patients required ventilatory support for longer than 24h postoperatively, and oral intake was started within 24h after extubation in all patients. Postoperative angiography confirmed graft patency and none of the patients developed any ischemic symptoms. All the patients were discharged between 1 and 2 months postoperatively. Thus, the off-pump technique is useful when concomitant diseases are present and will become an alternative method of treatment for coronary artery disease in selected patients.     

Heart rate reduction using edrophonium during coronary artery bypass grafting without cardiopulmonary bypass

Coronary artery bypass grafting without the use of cardiopulmonary bypass (CPB) is performed with increasing frequency. Performing revascularization on a beating heart is technically more demanding than performing revascularization on the arrested heart, especially in high-risk patients. beta-Blockers and calcium-channel antagonists have been used for the reduction of heart rate (HR) for the local immobilization of the anastomotic site. However, their negative inotropic actions often lead to serious hypotension. Therefore, we investigated the effect of edrophonium on HR reduction in high-risk patients undergoing CABG without CPB. Ten high-risk patients undergoing CABG without CPB were selected. To reduce HR during anastomosis, edrophonium was administered during the procedure. Systemic blood pressure (sBP), HR, and cardiac index (CI) were measured from the induction of anesthesia to the end of surgery. All surgeries were successfully performed without serious complications. To keep the rate under 60 bpm, edrophonium was administered at the time of anastomosis and this decreased the cardiac index from 2.19 to 1.95, while the sPB was maintained easily over 90 mmHg with the infusion of methoxamine. Edrophonium may be useful for the reduction of HR during coronary anastomosis in high-risk patients undergoing CABG without CPB.     

Midterm angiographic assessment of coronary artery bypass grafting without cardiopulmonary bypass

BACKGROUND: Coronary bypass surgery that provides good long-term graft patency can be performed on the beating heart as a viable alternative to conventional coronary artery bypass grafting (CABG). METHODS: From September 1993 to December 1996, 696 patients underwent CABG on the beating heart at the Ko?uyolu Heart and Research Hospital in Istanbul. Among them, 70 patients were chosen randomly for angiographic assessment of off-pump coronary artery bypass grafting. RESULTS: The interval from operation to angiography varied from 24 to 61 months (mean, 36.1+/-10.9 months). The patency rate of left internal mammary-left anterior descending artery anastomoses was 95.59% (patency achieved in 65 of 68 patients) and of vein grafts was 47.06% (patency achieved in 16 of 34 patients) (p < 0.0001). The patency rates of grafts anastomosed to the left anterior descending artery were significantly higher than the rates of the grafts anastomosed to the other coronary arteries (95.71% versus 45.45%, p < 0.0001). Multivariate analysis showed that graft type (p < 0.0001) and hyperlipidemia (p = 0.023) were significant predictors for graft occlusion. Left ventricular function improved significantly after CABG (p = 0.04). Reintervention (using percutaneous transluminal cardiac angioplasty) and reoperation rates were 0.97% and 1.4%, respectively. CONCLUSIONS: Off-pump coronary artery bypass grafting appears to produce midterm and long-term patency rates that are comparable to those of conventional techniques; that is especially true in cases of arterial conduits and of conduits anastomosed to the left anterior descending artery.     

Peripheral blood monocyte activation during coronary artery bypass grafting with or without cardiopulmonary bypass

OBJECTIVE: The aim of this prospective, randomized study was to investigate the impact of coronary artery bypass grafting (CABG) on peripheral monocytes and to evaluate the additional effect of cardiopulmonary bypass (CPB). DESIGN: Twenty patients admitted for elective CABG were randomized to either on-pump (ONCAB, n = 9) or off-pump (OFFCAB, n = 11) surgery and blood samples were drawn before, during and 24 h after the operation. The total number of monocytes and the proportion of the more mature CD16+/CD14+ monocytes were measured. Expression of activation markers (CD11b, CD35 and CD62L) and oxidative burst were determined using flow cytometry on both resting and in vitro stimulated cells. Serum concentrations of soluble CD14 and monocytes/macrophage chemotactic protein 1 (MCP-1) were analysed. RESULTS: During surgery there was a selective decrease in the proportion of CD16+/CD14+ monocytes compared to total monocytes. These had returned to preoperative values 24 h after surgery while the total number of monocytes had increased more than 100%. Intracellular production of oxygen free radical H2O2 was increased in the ONCAB group during surgery compared to OFFCAB. Monocyte expression and in vitro mobilization of complement receptors, CD11b and CD35, were similar in both study groups during and after surgery as was the expression of CD62L. Serum levels of MCP-1 decreased during surgery as did soluble CD14, both with increased levels again the day after surgery. CONCLUSION: It is concluded that the circulating monocyte population is activated during and as a consequence of CABG. There were few apparent additional effects of CPB found in this study. In this setting the inflammation caused by the surgery procedure per se probably surpasses the impact of the CPB on circulating blood monocytes.     

Peripheral blood monocyte activation during coronary artery bypass grafting with or without cardiopulmonary bypass

Objective. The aim of this prospective, randomized study was to investigate the impact of coronary artery bypass grafting (CABG) on peripheral monocytes and to evaluate the additional effect of cardiopulmonary bypass (CPB).

Design. Twenty patients admitted for elective CABG were randomized to either on-pump (ONCAB, n=9) or off-pump (OFFCAB, n=11) surgery and blood samples were drawn before, during and 24 h after the operation. The total number of monocytes and the proportion of the more mature CD16⁺/CD14⁺ monocytes were measured. Expression of activation markers (CD11b, CD35 and CD62L) and oxidative burst were determined using flow cytometry on both resting and in vitro stimulated cells. Serum concentrations of soluble CD14 and monocytes/macrophage chemotactic protein 1 (MCP-1) were analysed.

Results. During surgery there was a selective decrease in the proportion of CD16⁺/CD14⁺ monocytes compared to total monocytes. These had returned to preoperative values 24 h after surgery while the total number of monocytes had increased more than 100%. Intracellular production of oxygen free radical H₂O₂ was increased in the ONCAB group during surgery compared to OFFCAB. Monocyte expression and in vitro mobilization of complement receptors, CD11b and CD35, were similar in both study groups during and after surgery as was the expression of CD62L. Serum levels of MCP-1 decreased during surgery as did soluble CD14, both with increased levels again the day after surgery.

Conclusion. It is concluded that the circulating monocyte population is activated during and as a consequence of CABG. There were few apparent additional effects of CPB found in this study. In this setting the inflammation caused by the surgery procedure per se probably surpasses the impact of the CPB on circulating blood monocytes.     

Severe impairment of graft flow without electrocardiographic changes during coronary artery bypass grafting.

Early graft occlusion after coronary artery bypass grafting may have deleterious consequences. We routinely use transit-time flowmetry after termination of cardiopulmonary bypass, and we report five cases of early graft failure detected by the flowmeter. Electrocardiographic (ECG) changes were seen in only one of these five cases, and none of the patients had low cardiac output or other signs of graft failure at the end of the operation. The cause of graft failure was tagging in one case, rotation of internal mammary artery grafts in two and kinking of vein grafts in two cases. All errors were corrected, and control flowmetry showed normal flow rates after correction. Flowmetry takes less than 10 min, even with multiple bypass grafts. Based on our results, we advocate routine quality control with flowmetry after termination of cardiopulmonary bypass, since ECG changes are insufficient as checks of flow in bypass grafts.     

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

BACKGROUND: The feasibility of complete revascularization on the beating heart without cardiopulmonary bypass (CPB) as compared with the standard operation with CPB in elective low-risk patients with multivessel disease has not been clearly demonstrated in a prospective trial. METHODS: Eighty selected low-risk patients were enrolled. In preoperative study with coronary angiography, the decision was made whether complete revascularization without CPB could be performed. Patients were randomly assigned to receive CABG either with (n = 40) or without CPB (n = 40). Randomization criteria were age, sex, and left ventricular ejection fraction. Completeness of revascularization as well as short- and mid-term clinical outcome in a 13.4 +/- 6.5 month follow-up period were monitored. RESULTS: Twenty-six of 40 (65%) patients undergoing CABG without CPB underwent complete revascularization. In 5 of these patients (12.5%) suitable vessels were discarded for technical reasons and 9 patients (22.5%) were switched to CABG with CPB owing to the deeply intramyocardial course of target vessels (n = 5) or to hemodynamic instability (n = 4). In the group of patients operated on with CPB, 34 of 40 patients (85%) received complete revascularization. In 6 patients (15%) suitable vessels were discarded for technical reasons. Mean number of bypass grafts was 3.1 +/- 0.8 with CPB and 2.6 +/- 0.5 without CPB (p = 0.043). Clinical outcome and hospital stay were comparable in both groups. No patient died during the study period. No myocardial infarction was observed. Three patients undergoing CABG without CPB underwent successful PTCA 3 months after surgery. CONCLUSIONS: CABG without the use of CPB is effective for complete revascularization in the majority of selected low-risk patients. Nevertheless, it has to be stated that the rate of incomplete revascularization in this early series of CABG without CPB is higher, and compromises the basic principle of complete revascularization.     

Neurologic outcomes after coronary artery bypass grafting with and without cardiopulmonary bypass

Neurologic injury, in the form of either stroke or more subtle neurocognitive impairment, is a frequent and potentially devastating complication of coronary artery bypass grafting (CABG). The etiology of CABG-associated neurologic injury is likely multifactorial, with the phenomena of cerebral hypoperfusion and embolism being the major contributors. Several perioperative strategies have been developed in an effort to reduce the incidence of CABG-associated neurologic complications. Hypothermic cerebral perfusion, alpha stat acid-base management, and slow patient rewarming have been shown by several investigators to minimize adverse neurologic sequelae associated with the use of cardiopulmonary bypass. Performing CABG without cardiopulmonary bypass (off-pump CABG), meanwhile, has been shown to reduce the risk of perioperative stroke, especially in high-risk patients such as the elderly. Whether off-pump CABG reduces the incidence of less severe neurocognitive impairment has not yet been clearly established and merits further investigation in the form of large, multicenter, randomized trials. Other technical innovations, such as the use of sutureless and clampless aortic anastomotic devices, also may be able to further minimize the neurologic complications associated with CABG.     

Human cytokine responses to coronary artery bypass grafting with and without cardiopulmonary bypass.

BACKGROUND: Coronary artery bypass grafting (CABG) is associated with a systemic inflammatory response. This has been attributed to cytokine release caused by extracorporeal circulation and myocardial ischemia. This study compares the inflammatory response after CABG with cardiopulmonary bypass and after minimally invasive direct coronary artery bypass grafting (MIDCABG) without cardiopulmonary bypass. METHODS: Cytokine release and complement activation (interleukin-6 and interleukin-8, soluble tumor necrosis factor receptors 1 and 2, complement factor C3a, and C1 esterase inhibitor) were determined in 24 patients before and after CABG or MIDCABG. The maximum body temperature, chest drainage, and fluid balance were recorded for 24 hours after operation. RESULTS: Release of interleukin-6, interleukin-8, and tumor necrosis factor receptors 1 and 2 was significantly higher (p < or = 0.005) in the CABG group than the MIDCABG group just after operation. After 24 hours, a significant increase in interleukin-6 was also found in the MIDCABG group (p = 0.001) compared with preoperative value. Body temperature and fluid balance were significantly higher after CABG (p < or = 0.001). CONCLUSIONS: Minimally invasive direct coronary artery bypass grafting represents a less traumatizing technique of surgical revascularization. The reduction in the inflammatory response may be advantageous for patients with a high degree of comorbidity.     

Real-time three-dimensional echocardiography evaluation of graft anastomoses during coronary artery bypass grafting: preliminary experience

Three-dimensional echocardiography has been intensively developed recently, and it is expected to overcome the limitations of two-dimensional echocardiography. We describe the usefulness of our original real-time three-dimensional system for evaluating graft anastomoses during coronary artery bypass grafting operations.     

Intraoperative massive pulmonary embolism during coronary artery bypass grafting

A 66-year-old female underwent elective coronary artery bypass grafting (CABG). Massive pulmonary embolism developed intraoperatively shortly after weaning from cardiopulmonary bypass. A 25-cm large venous embolus was extracted from pulmonary artery by consequently performed open pulmonary embolectomy on the beating heart. Source of extracted embolus was not postoperatively revealed. Patient remained angina-free and with no evidence of pulmonary hypertension at the 6-month follow-up.     

Intraoperative imaging techniques to assess coronary artery bypass graft patency

Graft patency verification is increasingly recognized as an important component of coronary artery bypass grafting. Intuitively, eliminating intraoperative graft failure should reduce cardiac mortality and morbidity in the short term and improve clinical outcome in the long term. Although conventional angiography remains the gold standard technique for assessing graft patency, it is rarely available in the operating room and consequently several other less invasive approaches have been advocated. This article reviews the two currently most commonly used modalities for graft patency assessment, intraoperative fluorescence imaging and transit-time flowmetry, and discusses their value and limitations. Both techniques can reliably detect otherwise unsuspected occluded grafts and this is crucial for internal thoracic arteries because of their prognostic significance. Although neither technology can consistently identify more minor, non-occlusive abnormalities, the intraoperative fluorescence imaging technique seems to be more sensitive and less susceptible to "false positive" images.     

Activation of hemostasis after coronary artery bypass grafting with or without cardiopulmonary bypass

Activation of coagulation, fibrinolysis, and the vascular endothelium occurs after heart surgery with cardiopulmonary bypass (CPB), but the effects of eliminating CPB in patients undergoing coronary artery bypass grafting (CABG) are unknown. Therefore, we compared the hemostatic profiles of off-pump and on-pump CABG patients. Two groups of consecutive patients participating in a larger trial (the Octopus Trial) were randomly allocated to undergo CABG with (n = 20) or without (n = 20) CPB. Platelet numbers and plasma concentrations of P-selectin, prothrombin fragment 1.2 (F1.2), soluble fibrin, d-dimers, and von Willebrand factor (as a marker of endothelial cell activation) were measured and corrected for hemodilution. Compared with the on-pump CABG group, F1.2 and d-dimer levels were significantly lower (P = 0.004 and P = 0.03, respectively) in patients having CABG surgery performed off-pump. In the CPB group, F1.2 (median [interquartile range], 450% of baseline [233%-847%]) and d-dimer (538% [318%-1192%]) peaked in the immediate postoperative period and remained increased until Day 4, whereas in the off-pump group, F1.2 and d-dimer levels increased more gradually and peaked on Day 4 (342% [248%-515%] and 555% [387%-882%], respectively). In both groups, von Willebrand factor concentrations were increased until Day 4 (CPB, 308% [228%-405%]; off-pump, 288% [167%-334%]). Despite heparinization, CABG surgery with CPB was associated with excessive thrombin generation and fibrinolytic activity immediately after surgery. The off-pump group demonstrated a delayed postoperative response that became equal in magnitude to the CPB in the later (20-96 h) postoperative period.     

Intraoperative color Doppler ultrasound assessment of LIMA-to-LAD anastomoses in off-pump coronary artery bypass grafting

BACKGROUND: Although techniques for off-pump coronary artery bypass grafting (CABG) are continually being refined, angiographic follow-up studies have indicated a higher rate of anastomoses-related stenoses than expected after traditional on-pump CABG. This study was performed to evaluate the use of intraoperative epicardial color Doppler ultrasound to quality-assess left internal mammary artery (LIMA) to left anterior descending coronary artery (LAD) anastomoses performed on the beating heart. METHODS: Twenty-four LIMA-to-LAD anastomoses were evaluated with real-time epicardial ultrasound imaging using an ultrasound transducer positioned between the paddles of the stabilizer during off-pump procedures. The length of the anastomosis (D(A)), diameters of LIMA (D(M)), LAD at the toe of the anastomosis (D1), and 5 mm distally to the anastomosis (D2) were measured, and the ratios between these variables were calculated. The flow velocity through the anastomoses was visualized by color Doppler coding, and flow was assessed with transit-time flowmetry. RESULTS: The epicardial color Doppler ultrasound allowed accurate assessment of the anastomoses. Twenty-three (96%) of the primary anastomoses were confirmed as patent. Mean ratios of D1/D2, D(A)/D2, and D(M)/D2 were 0.89 +/- 0.13, 3.01 +/- 1.04 and 1.32 +/- 0.32, respectively. One anastomosis had a stenosis more than 50% detected by color Doppler ultrasound. After surgical revision, transit-time flow increased from 22 to 40 ml/min. CONCLUSIONS: Intraoperative color Doppler ultrasound allowed adequate imaging for quality assessment of LIMA-to-LAD anastomoses performed on the beating heart. One anastomosis was revised due to a technical error detected by epicardial color Doppler imaging. Epicardial ultrasound scanning is a valuable tool for intraoperative assessment of LIMA-to-LAD anastomoses during off-pump coronary surgery.     

Effect of cardiopulmonary bypass on cortical cerebral oxygenation during coronary artery bypass grafting.

OBJECTIVE: To investigate the changes in cerebral oxygenation during coronary artery bypass grafting (CABG) with normothermic cardiopulmonary bypass (CPB) using near infrared spectroscopy. METHODS: Measurement of cerebral cortical oxygenation changes included concentration of deoxygenated haemoglobin [HHb], oxygenated haemoglobin [O(2)Hb], changes in the redox status of the cytochrome c oxidase [Cyt-Ox], cerebral saturation as expressed by the tissue oxygenation index (TOI), and cerebral blood volume (CBV) as expressed by tissue haemoglobin index (THI). Measurements were performed in 19 consecutive patients undergoing normothermic (34-36 degrees C) CPB. Data were recorded at 0.5s intervals and averaged into 30 s epochs. Data analysis was carried at baseline, 1, 20, and 40 min after start of CPB, at rewarming, on weaning from CPB, and at closing of chest. RESULTS: There were no in-hospital death, neurological deficits, or myocardial infarcts. Compared to baseline, during the entire CPB duration, there was a marked reduction in [O(2)Hb] and CBV which reached their worst level 40 min after initiation of CPB (from -3.03+/-5.1 to -9.25+/-7.20 micromol/l for [O(2)Hb], and a 24% reduction for CBV (both P<0.0001). The deterioration in [O(2)Hb] was recovered by the end of surgery, while the changes in CBV persisted. No significant changes occurred with respect to [HHb], [Cyt-Ox], and TOI. CONCLUSIONS: Conventional CABG is responsible for deterioration in [O(2)Hb], and CBV, which peak at 40-60 min following initiation of CPB. The changes in [O(2)Hb] are reversible whereas the reduction of CBV persists to the end of the surgery. This suggests a transient impairment in the autoregulatory mechanisms controlling cerebral blood flow following discontinuation of cardiopulmonary bypass.