Embracing the heart: perioperative management of patients undergoing off-pump coronary artery bypass grafting using the octopus tissue stabilizer

Morphologic Evaluation of the Mitral Annulus During Displacement of the Heart in Off-Pump Coronary Artery Bypass Surgery

OBJECTIVE

To evaluate the morphologic changes of the mitral annulus using 3-dimensional transesophageal echocardiography during heart displacement to expose the anastomosis site in off-pump coronary artery bypass surgery (OPCAB).

DESIGN

Prospective case series.

SETTING

Single center, university hospital.

PARTICIPANTS

The study comprised 34 consecutive patients who underwent OPCAB of the left circumflex artery (LCX) and the right coronary artery (RCA).

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Mitral annulus parameters were measured using the Mitral Valve Quantification program after sternotomy (physiologic position) and during displacement of the heart to expose the LCX (LCX position) and the RCA (RCA position). The height of the mitral annulus was significantly lower in the LCX (5.76 ± 0.90 mm) and RCA (5.92 ± 0.97 mm) positions than in the physiologic position (6.96 ± 0.99 mm; both p < 0.0001). The percent change in the height of the mitral annulus was significantly greater in the mitral regurgitation group than in the mitral regurgitation nondeterioration group when in the LCX (-16.3% ± 6.0% v -11.9% ± 3.3%, p = 0.0203) and RCA (-16.9% ± 6.3% v -12.1% ± 3.8%, p = 0.0207) positions. The anteroposterior and intercommissural diameters, annulus perimeter, and surface area of the mitral annulus did not differ significantly among all heart positions.

CONCLUSIONS

The mitral annulus flattened and lost its saddle shape without expanding while in the LCX and RCA positions. The greater percent change in the height of the mitral annulus may aggravate mitral regurgitation.

Anesthetic challenges in minimally invasive cardiac surgery: Are we moving in a right direction?

Continuously growing patient's demand, technological innovation, and surgical expertise have led to the widespread popularity of minimally invasive cardiac surgery (MICS). Patient's demand is being driven by less surgical trauma, reduced scarring, lesser pain, substantially lesser duration of hospital stay, and early return to normal activity. In addition, MICS decreases the incidence of postoperative respiratory dysfunction, chronic pain, chest instability, deep sternal wound infection, bleeding, and atrial fibrillation. Widespread media coverage, competition among surgeons and hospitals, and their associated brand values have further contributed in raising awareness among patients. In this process, surgeons and anesthesiologist have moved from the comfort of traditional wide incision surgeries to more challenging and intensively skilled MICS. A wide variety of cardiac lesions, techniques, and approaches coupled with a significant learning curve have made the anesthesiologist's job a challenging one. Anesthesiologists facilitate in providing optimal surgical settings beginning with lung isolation, confirmation of diagnosis, cannula placement, and cardioplegia delivery. However, the concern remains and it mainly relates to patient safety, prolonged intraoperative duration, and reduced surgical exposure leading to suboptimal treatment. The risk of neurological complications, aortic injury, phrenic nerve palsy, and peripheral vascular thromboembolism can be reduced by proper preoperative evaluation and patient selection. Nevertheless, advancement in surgical instruments, perfusion practices, increasing use of transesophageal echocardiography, and accumulating experience of surgeons and anesthesiologist have somewhat helped in amelioration of these valid concerns. A patient-centric approach and clear communication between the surgeon, anesthesiologist, and perfusionist are vital for the success of MICS.

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

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

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

Background

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

Methods

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

Results

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

Conclusions

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

Deep pericardial suture vs apical suction for off-pump bypass grafting

Hemodynamic changes during heart luxation and stabilization are major problems in off-pump coronary artery bypass surgery. The hemodynamic effects of an apical suction device were compared with those of the classic posterior pericardial suture in 45 patients with multivessel coronary disease undergoing off-pump coronary artery bypass. Mean age was 63.78 +/- 8.11 years; 31 patients were male and 14 were female. Transesophageal Doppler echocardiography was used for hemodynamic monitoring. All hemodynamic parameters were significantly better when the apical suction device was used to position the heart for anastomoses on the posterior descending and circumflex arteries.

Intraoperative Transesophagial Echocardiography Modifies Strategy in Off-Pump Coronary Artery Bypass Grafting

BACKGROUND

Off-pump coronary artery bypass graft surgery (OPCAB) can improve operative morbidity and mortality in high risk patients. Intraoperative transesophageal echocardiography (ITEE) is being employed increasingly during cardiac surgery.

METHODS

Routine ITEE was performed in 744 OPCAB patients performed over a five year period. Mean patient age was 69.1 +/- 8.0 years. There were a high percentage of patients over 70 years (39%), diabetics (26%), poor left ventricular function (< or = 35%) (31%), recent myocardial infarction (24%), unstable angina (15%), and preoperative intraaortic balloon pump (5.6%); mean graft number was 3.4.

RESULTS

There was a major modification in intraoperative strategy in 117 patients (16%) and minor modification in 77 patients (10%) due to information available through the ITEE (total 26%). Graft revision was performed in 39 patients, graft construction was modified due to severe ascending aortic atherosclerosis in 31, and an intraoperative intraaortic balloon pump was placed due to previously underappreciated left ventricular dysfunction and new intraoperative left ventricular dysfunction in 37 patients. Ten patients were placed on cardiopulmonary bypass due to previously unknown intracardiac pathology (three atrial septal defect repairs and five valvular procedures, two others). Intracoronary shunts were placed due to new wall motion changes during anastomosis in 77 patients. There were two emergent conversions to cardiopulmonary bypass. There were no complications due to ITEE probe placement.

CONCLUSIONS

Intraoperative transesophageal echocardiography is a valuable adjunct and can result in a major change of surgical strategy in a significant number of patients when used routinely for OPCAB. It may also improve surgical outcome and add to the OPCAB benefits.

Effects of on-pump versus off-pump coronary artery bypass graft surgery on right ventricular function

OBJECTIVES

Right ventricular dysfunction is a possible cause of cardiac failure after coronary surgery. The use of cardiopulmonary bypass is regarded as a major cause for its occurrence, and it has been postulated that performing coronary surgery without cardiopulmonary bypass might reduce ventricular dysfunction. Therefore, this prospective, randomized, controlled study tested the hypothesis that off-pump coronary surgery would better preserve right ventricular systolic and diastolic function than conventional bypass surgery.

METHODS

Fifty patients scheduled for elective coronary artery bypass surgery were randomly assigned to conventional or off-pump surgery. Right ventricular function was assessed by intraoperative transesophageal echocardiography immediately before and after coronary surgery. Right ventricular ejection fraction was used as a marker of global systolic function and tricuspid early/late (atrial) ratio as a marker of the global diastolic function. Peak systolic and early diastolic velocities of the lateral tricuspid annulus were studied to assess systolic and diastolic function in the area of the right ventricular free wall.

RESULTS

Surgery was completed according to randomization in 48 of 50 patients. Preoperative characteristics were similar in both groups. Intraoperative differences between the two groups included a higher volume of allogeneic blood transfusion in the conventional surgery group. At the end of surgery, global systolic right ventricular function was similarly maintained and diastolic function similarly impaired in both groups. There were no significant intergroup differences in any of the echocardiographic markers of right ventricular function.

CONCLUSIONS

Off-pump surgery did not better preserve right ventricular systolic and diastolic function than did conventional coronary surgery.

Clinical Outcomes of Low-Risk Patients Undergoing Beating-Heart Surgery With or Without Pulmonary Artery Catheterization

OBJECTIVE

For patients who undergo off-pump coronary artery bypass (OPCAB) surgery, pulmonary artery catheterization (PAC) has been proposed as a useful intraoperative monitoring tool. This study was designed to determine if the choice of PAC versus central venous pressure monitoring (CVP) had any effect on outcome after OPCAB. This study compared these 2 methods of hemodynamic monitoring in low-risk patients undergoing beating-heart surgery via a median sternotomy and evaluated their effect on morbidity and in-hospital mortality.

DESIGN

Retrospective database and medical record review.

SETTING

Tertiary care teaching hospital.

PARTICIPANTS

Low-risk patients who had coronary revascularization via a median sternotomy on the beating heart.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

A population of 2,414 low-risk patients who had beating-heart coronary revascularization between January 2000 and December 2003 was reviewed. Most patients (1,671 or 69.2%) received a PAC, whereas 743 (30.8%) had CVP monitoring. Risk-adjusted logistic regression analyses were performed to investigate the effect of each technique on clinical outcomes. The groups were comparable in both baseline characteristics and Parsonett's mortality risk (1.5 +/- 0.9, p = 0.58). Univariate analysis failed to show a difference in operative mortality (p = 0.76), on-pump conversion rate for completion of aortocoronary bypasses (p = 0.82), postoperative low cardiac output (p = 0.10), or prolonged inotropic agent use (p = 0.22). Similarly, in the multivariate analysis, both groups had a similar rate of conversion to an on-pump procedure for completion of coronary artery grafting (p = 0.91), intraoperative intra-aortic balloon pump use (p = 0.69), low cardiac output state (p = 0.16), or in-hospital mortality (p = 0.51).

CONCLUSIONS

This single-institution, retrospective study suggests that in low-risk patients undergoing beating-heart surgery, CVP monitoring may be sufficient.

Midterm Results of Off-Pump Coronary Artery Bypass Surgery in 136 Patients: An Angiographic Control Study

BACKGROUND

Off-pump coronary artery bypass surgery may provide an alternative form of surgical revascularization by avoiding the complications of cardiopulmonary bypass (CPB). This study summarizes the midterm results of 136 off-pump bypass surgery patients.

METHODS

Between January 2000 and March 2002, out of 178 surgical myocardial revascularizations, 136 (76.4%) were off-pump bypass surgery. Complete revascularization was done and especially arterial grafts were used. All patients were followed clinically and with treadmill test for 2 years. Average control angiography was performed at the end of 2-year follow-up.

RESULTS

Of all the patients, 56.7% were male and the mean age of the patients was 63.6 +/- 7.4 years. A total of 481 anastomoses were performed-136 (28.27%) to the left anterior descending artery (LAD), 135 (28.07%) to the circumflex coronary artery (Cx) branches, 102 (21.20%) to the right coronary artery (RCA), 108 (22.46%) to the Di. The mean graft number was 3.46. We used 96.6% of patients' left internal mammarian artery (LITA), 29.2% radial artery (RA), 4.4% right internal thoracic artery (RITA), and 100% saphenous vein. There were ischemic changes within 12 patients. All ischemic changes came back to normal within 4 and 18 hours, postoperatively. Mean extubation time was 5.36 +/- 2.23 hours, mean stay in intensive care unit was 17.53 +/- 3.15 hours, mean hospital stay was 5.03 +/- 1.29 days. The LITA patency was 99.25%, RA patency was 97.84%, RITA patency was 100%, and saphenous vein patency was 91.79% with control angiography.

CONCLUSION

Off-pump coronary artery bypass graft (CABG) is efficient procedure with lower index of mortality, morbidity, ICU stay, hospital stay, good wound healing, early socialization, and results in lower costs.

High thoracic epidural anesthesia and coronary artery disease in surgical and non-surgical patients

PURPOSE OF REVIEW

Even though high thoracic epidural anesthesia has been shown to be highly efficacious in the control of symptoms in refractory angina, its general use is still restricted. In patients who undergo coronary revascularization, however, the technique is becoming more and more popular. The present review outlines the use of high thoracic epidural anesthesia in patients with ischemic heart disease who underwent coronary revascularization in order to further reveal high thoracic epidural anesthesia's low complication rate and to analyze why physicians still refrain from using it more frequently.

RECENT FINDINGS

The incidence of severe hemodynamic complications after high thoracic epidural anesthesia is low in patients with coronary artery disease. The main advantage would be a myocardial sympathectomy leading to an improvement in the oxygen input-demand relationship. Likewise, a decrease in mortality due to respiratory complications could not be shown. In patients undergoing myocardial revascularization with full anticoagulation there is an increased risk of epidural hematoma formation. Its precise risk is difficult to evaluate. There is an overall low rate of epidural hematomas as a result of high thoracic epidural anesthesia. With the available data, the incidence has been estimated at between 1/1500 and 1/10,000.

SUMMARY

Epidural anesthesia does not decrease mortality or the incidence of myocardial infarction after coronary artery bypass grafting. It reduces the incidence of arrhythmias and respiratory complications and improves the quality of analgesia. High thoracic epidural anesthesia has been shown to be a safe and efficient technique for refractory angina that reduces the frequency of ischemic events and improves the clinical condition of patients.

Ninety-degree anterior cardiac displacement in off-pump coronary artery bypass grafting: the Starfish cardiac positioner preserves stroke volume and arterial pressure

PURPOSE

In off-pump coronary surgery through sternotomy, exposure of posterior circumflex branches causes circulatory deterioration in both patients and pigs. We assessed cardiac pump function when displacing the pig heart anteriorly with a suction cardiac positioner.

DESCRIPTION

Six pigs (+/-80 kg) underwent sternotomy for hemodynamic instrumentation using catheter-tipped manometers and paced at 80 beats/min. Ultrasound flow probes were placed around the aorta and proximal coronary arteries. The heart was retracted anteriorly to 90 degrees with the Starfish cardiac positioner attached to the apex by means of suction (-400 mm Hg). Retraction was guided by cardiac output monitoring.

EVALUATION

Anterior displacement to 90 degrees facilitated full exposure of posterior arteries. Stroke volume and mean arterial pressure decreased to 94% +/- 13% (mean +/- SD, p = 0.135) and 95% +/- 13% (p = 0.09) of control values, respectively. Right and left ventricular end-diastolic pressure increased to 129% +/- 37% (p = 0.009) and to 128% +/- 57% (p = 0.235), respectively. Coronary flow remained unchanged. Additional 15-degree head-down positioning increased stroke volume to 113% +/- 17% (p = 0.015) and mean arterial pressure to 113% +/- 25% (p = 0.087) at the expense of further increased right and left ventricular end-diastolic pressure (186% +/- 63%, p < 0.001 and 157% +/- 49%, p < 0.001, respectively).

CONCLUSIONS

When lifting the porcine heart ninety degrees anteriorly, the Starfish cardiac positioner facilitated exposure of posterior branches and, when guided by cardiac output, preserved stroke volume and arterial pressure.

High thoracic epidural anesthesia for off-pump coronary artery bypass surgery

OBJECTIVE

To assess the feasibility of high thoracic epidural anesthesia combined with sevoflurane for off-pump coronary artery bypass surgery and to evaluate the postoperative pain control, side effects, and perioperative hemodynamics.

DESIGN

Retrospective review of prospectively collected data.

SETTING

A university teaching hospital.

PARTICIPANTS

One hundred six consecutive patients receiving thoracic epidural combined with sevoflurane.

INTERVENTION

From November 1999, the patients undergoing off-pump coronary artery bypass grafting were offered the epidural-inhalation anesthetic approach.

MEASUREMENTS AND MAIN RESULTS

Insertion of the epidural catheter was successful in all but 2 patients; 1 bloody tap occurred and the dura was never punctured, although 1 patient presented with postoperative paraplegia. An emergency spinal cord nuclear magnetic resonance excluded signs of medullary compression caused by epidural or spinal hematoma. Visual analog scale scores for pain during the first 24-hour period were < 2 in all patients. Mean time to extubation was 4.6 +/- 2.9 hours. The average intensive care unit stay was 1.5 +/- 0.8 days. Incidences of perioperative myocardial infarction, myocardial ischemia, and atrial fibrillation were 2.8%, 7.5%, and 10.6%, respectively. Two patients died: 1 from multiorgan failure and the other from myocardial infarction. Heart rate, mean arterial pressure, cardiac index, and systemic vascular resistance were not affected by thoracic epidural alone. Mean arterial pressure and cardiac index decreased (p < 0.05) when general anesthesia was induced and remained stable thereafter. Neither heart rate nor systemic vascular resistance changed from baseline during operation.

CONCLUSIONS

Thoracic epidural as an adjunct to general anesthesia is a feasible technique in off-pump coronary artery bypass surgery. It induces intense postoperative analgesia and does not compromise central hemodynamics.

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

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

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.

Endoscopic exposure and stabilization of posterior and inferior branches using the endo-starfish cardiac positioner and the endo-octopus stabilizer for closed-chest beating heart multivessel CABG: hemodynamic changes in the pig

BACKGROUND

Closed-chest, off-pump, multivessel CABG requires modified instruments to expose and stabilize posterior and inferior coronary branches. Using three new prototype devices, we explored the feasibility of endoscopic bypass grafting on these branches and assessed cardiac function during cardiac displacement.

METHODS

Eight pigs (75 to 85 kg) were instrumented for hemodynamics and paced at 80 to 100 bpm. After closure of the sternotomy wound, the Da Vinci endoscope was inserted subxiphoidally. A sternal hook was used to hoist the sternum ventrally by 5 cm. The articulating EndoStarfish cardiac positioner was placed through a trocar (Ø12 mm). The positioner was fixed to the apex using -400 mm Hg suction and the heart was displaced anteriorly to 90 degrees. In 12 other pigs (75 to 85 kg), both internal mammary arteries (IMA) were harvested and the sternal wound was closed. Five trocar ports were placed for instrumentation (Ø12 mm, two in left chest, two in right chest, and one subxiphoidally). For coronary stabilization, a novel deployable EndoOctopus cardiac stabilizer was employed (suction -400 mm Hg). The Da Vinci robot-telemanipulator system was used for endoscopic grafting of the left and right IMA on posterior and inferior branches (16 anastomoses).

RESULTS

When circumflex arteries were fully exposed and accessible for coronary surgery, stroke volume decreased by 18%+/-3 versus baseline (P=0.02) and mean arterial pressure decreased by 27%+/-6 (P=0.001). Additional 10 degrees Trendelenburg head-down positioning normalized stroke volume and arterial pressure. In the displaced heart, obtuse marginal branches (OM) and the ramus descending posterior (RDP) of the right coronary artery became fully exposed with a mean arterial pressure >70 mm Hg during grafting. No accidental detachment occurred. Coronary target motion was restrained to approximately 1x1 mm. In two test cases, five sham distal anastomoses were created (grafts sewn to epicardium, left IMA to OM2 jump to OM3, right IMA to RDP, and composite graft from left IMA jump to diagonal branch). In 10 animals, 16 successfully completed anastomoses to RPD and OM branches of Ø1.75 to 2.5 mm required 25 to 60 minutes each to construct. At sacrifice, all anastomoses were patent.

CONCLUSIONS

In the closed-chest pig in Trendelenburg position and during lifting of the sternum, the EndoStarfish and EndoOctopus enabled IMA grafting of posterior and inferior branches on the beating heart without mean arterial pressure dropping below 70 mm Hg.

Anaesthesia for coronary artery bypass: should it differ off-pump and on-pump?

The advent of suction myocardial stabilizers has caused a resurgence in offpump coronary artery bypass (OPCAB). It may avoid end-organ injury associated with cardiopulmonary bypass, e.g. stroke, neuropsychological and renal dysfunction. Both low- and high-risk patients have improved outcomes with OPCAB (Moshkovitz et al, 1995; Nierich et al, 1999; Arom et al, 2000).

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.

A prospective evaluation of hemodynamic instability during off-pump coronary artery bypass surgery

OBJECTIVE

Despite recognized hemodynamic derangements during cardiac displacement, most patients appear to tolerate the off-pump procedure well. However, some patients unpredictably become hemodynamically unstable requiring emergency cardiopulmonary bypass or intra-aortic balloon pump support. After an experience of 5306 multivessel off-pump coronary artery bypasses (OPCABs), this study was undertaken to determine the factors that would identify the patients who were at a higher risk for the procedure.

DESIGN

Prospective clinical investigation.

SETTING

Tertiary care academic cardiac care center.

PARTICIPANTS

Five hundred consecutive patients undergoing multivessel OPCAB from September to December 2001.

INTERVENTIONS

Various cardiac and extracardiac factors were charted in prespecified data-entry forms. Multiple logistic regression analysis was done to determine if any identifiable factors were predictors of a higher risk of unacceptable hemodynamic instability during OPCAB. Institution of IABP support or conversion to CPB were the endpoints of the study.

MEASUREMENTS AND MAIN RESULTS

Of the 500 patients studied, significant hemodynamic instability developed in 24 (4.8%) patients. IABP support was instituted in 16 (3.2%) patients, and 8 (1.6%) were converted to CPB. Stepwise logistic regression identified ejection fraction <25% (p < 0.001), myocardial infarction of <1-month duration (p = 0.009), congestive heart failure (p = 0.016), and preoperative hemodynamic instability (p = 0.057) as predictors of conversion during OPCAB.

CONCLUSIONS

Patients with low left ventricular ejection fraction <25%, myocardial infarction of <1-month duration, congestive heart failure, or preoperative hemodynamic instability constitute the high-risk group for OPCAB.

Current trends and technique in OPCAB surgery

BACKGROUND AND AIM OF THE STUDY

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

METHODS

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

RESULTS

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

CONCLUSION

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

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.

Hemodynamic changes during displacement of the beating heart using epicardial stabilization for off-pump coronary artery bypass graft surgery

OBJECTIVE

To evaluate the hemodynamic alterations during off-pump coronary artery bypass graft surgery to determine the degree of impairment caused and the techniques to rectify them.

DESIGN

Prospective, observational cohort study performed from January 2000 through September 2000.

PARTICIPANTS

Patients (n = 500) with coronary artery disease undergoing multivessel off-pump coronary artery bypass graft surgery using the Octopus tissue stabilizer (Medtronic, Inc, Minneapolis, MN). Unstable patients with ongoing ischemia were excluded from the study.

INTERVENTIONS

All patients were monitored with radial artery and pulmonary artery catheters and continuous transesophageal echocardiography monitoring with a multiplane transducer. The perioperative requirement of an intracoronary shunt, inotropes, or an intra-aortic balloon pump was noted. The effect of the Trendelenburg position and fluids on hemodynamics was observed. The need for defibrillation and institution of emergency cardiopulmonary bypass were major endpoints to determine the inability of the patient to tolerate displacement of the heart.

MEASUREMENTS AND MAIN RESULTS

Mean patient age was 59.3 +/- 11.6 years. There were 204 (40%) patients in the high-risk category; 54 (10.8%) patients had left ventricular ejection fraction <25%. The mean number of grafts was 2.7 +/- 0.8. Vertical displacement of the heart to access the lateral and inferior walls decreased the mean arterial pressure by 18 +/- 4% (p < 0.01), with a concomitant increase in central venous pressure of 66 +/- 18% (p < 0.001). The stroke volume and the cardiac index were reduced by 35.7 +/- 11% (p < 0.001) and 45 +/- 13% (p < 0.001). On transesophageal echocardiography, there was development of new regional wall motion abnormalities in 59.2% and a decrease in global left ventricular functions in 61.2%. The use of inotropes was highest during anastomosis on the posterior wall-78.4% compared with 21.9% for the anterior wall. An intra-aortic balloon pump was used in 55 (11.2%) patients, and 7 (0.71 %) patients had to be put on emergency CPB. The in-hospital mortality was 1.2%.

CONCLUSION

Most patients had hemodynamic changes easily correctable by fluids and inotropes. Monitoring of left ventricular and right ventricular function by transesophageal echocardiography enhances safety of the procedure and is recommended. The use of the Octopus II tissue stabilizer proved to be a safe and versatile means to stabilize the heart during off-pump coronary artery bypass procedures, especially in high-risk patients.

Myocardial Protection During Minimally Invasive Cardiac Surgery

Minimally invasive cardiac surgery or beating heart surgery requires very precise observation, explanation, diagnosis, and proper treatment of all changes in the cardiovascular system that occur during the procedure. A major concern in beating heart surgery is the risk of inducing myocardial ischemia without the circulatory support of cardiopulmonary bypass. Protection of myocardium in different stages of the perioperative period is crucial. The following issues should be taken into consideration: preoperative preparation of the myocardium, providing anesthesia techniques that may help to protect the myocardium, and the use of surgical techniques for myocardial protection. Hemodynamic alterations during dislocations of the heart require understanding of these changes and the effects they have on the myocardium. Proper monitoring during the whole procedure, correlation of all findings with the treatment and therapeutic maneuvers, and excellent cooperation between anesthesiologist and surgeon are essential for myocardial protection. New pharmacologic methods, some experimental, should be considered in near future for myocardial protection during beating heart surgery.

Beating-heart coronary artery bypass graft surgery at San Raffaele Hospital: four years of experience

OBJECTIVE

To review the database of 1,902 consecutive patients who underwent coronary artery bypass graft (CABG) surgery in the period 1998 through 2001 at this institution, and to compare the preoperative status, anesthetic management, and postoperative outcome of 364 patients with the beating-heart technique with 1,538 patients who underwent the operation on cardiopulmonary bypass.

DESIGN

Observational study.

SETTING

University hospital.

PARTICIPANTS

Consecutive patients (n = 1,902) who underwent CABG surgery in the period 1998 through 2001.

MEASUREMENTS AND MAIN RESULTS

Comparison (chi-square test) of the preoperative status shows that surgeons' choice for the beating-heart technique was based on the presence of severe preoperative comorbidities: renal impairment (p < 0.0001), chronic obstructive pulmonary disease (p < 0.04), and low ejection fraction (p < 0.0001). On a multivariate analysis, the beating-heart technique was associated with reduced transfusion needs and duration of mechanical ventilation.

CONCLUSION

Beating-heart surgery is gaining popularity as a safe method for myocardial revascularization. Excellent results have been achieved with this technique in this center.

Routine immediate extubation for off-pump coronary artery bypass grafting without thoracic epidural analgesia

BACKGROUND

The expansion of coronary surgery on the beating heart without cardiopulmonary bypass has led to increasing interest in ultra-fast track anesthesia, allowing extubation of the patient in the operating theater. The techniques described to date combined general anesthesia with thoracic epidural analgesia. We report the routine application of a technique that allows immediate extubation in the majority of patients undergoing off-pump coronary artery bypass grafting without thoracic epidural analgesia.

METHODS

Fast-track anesthesia using an ultra-shortacting opiate remifentanil, without epidural catheter insertion, was used in 160 unselected patients undergoing off-pump coronary artery bypass grafting (aged 43 to 83 years, mean 65 years). There were an average of 2.2 bypass procedures per patient, with the left internal mammary artery used in 93%. Contraindications to immediate extubation were (except for failure to meet standard extubation criteria) hemodynamic instability and persistent bleeding at the end of operation. Satisfactory postoperative pain control was achieved by continuous remifentanil (0.0125 to 0.05 microg x kg(-1) x min(-1)).

RESULTS

Operating theater extubation within 10 minutes of the end of operation was feasible in 150 patients (94%). Five patients (3%) were extubated within 2 hours, and the remaining 5 patients (3%) were converted to standard anesthesia. There were no deaths during hospitalization. Major complications included myocardial infarction and transient ischemic attacks (2 patients each). No pulmonary complications were seen. Episodes of atrial fibrillation occurred in 21% of the patients undergoing operation.

CONCLUSIONS

Immediate extubation is possible in most patients after off-pump coronary artery bypass grafting even without thoracic epidural analgesia. We believe this type of less invasive cardiac anesthesia is safe and promising.

Off-pump coronary artery surgery

Cardiopulmonary bypass has several associated deleterious effects that include a systemic inflammatory response, coagulopathy, central nervous system complications and a variable degree of end-organ damage. The recent upsurge in interest in "beating-heart" surgery attempts to avoid these deleterious effects. Advances in surgical technique, such as the use of intracoronary shunts and the Octopus retractor, have made beating-heart surgery a reality. The challenges for the anaesthetist are greater than for coronary artery surgery using cardiopulmonary bypass, and whilst some advantages are proven, such as the lack of the inflammatory response and the decreased need for blood or blood products, others have yet to be proved and there is a need for further research. The advantages and disadvantages need to be evaluated in randomised studies in order to confirm the safety and efficacy of these new techniques in terms of long-term graft patency and decreased morbidity.

Mitral annulus distortion during beating heart surgery: a potential cause for hemodynamic disturbance--a three-dimensional echocardiography reconstruction study

BACKGROUND

Positioning for access to the coronary arteries leads to hemodynamic instability during off-pump cardiac surgery. External changes have been well described, but a description of the intracardiac structures in humans has not been described.

METHODS

With multiplane intraoperative echocardiography, the mitral annulus at end diastole was reconstructed in the different positions and correlated with hemodynamic changes in the right heart and left atrium.

RESULTS

Significant distortion of the mitral annulus with enlargement of the left atrium and pulmonary veins was demonstrated, which correlated with high left atrial pressures.

CONCLUSIONS

Mitral valve distortion can significantly contribute to hemodynamic instability during positioning for off-pump cardiac surgery.

Off-pump coronary artery bypass grafting: new developments but a better outcome?

Off-pump coronary artery surgery is now performed safely and effectively without cardiopulmonary bypass. This review includes indications, approaches, anaesthetic and haemodynamic management, and compares the occurrence of postoperative complications and multiorgan dysfunction with conventional cardiac surgery.

To ventilate or not after minimally invasive direct coronary artery bypass surgery: the role of epidural anesthesia

OBJECTIVE

To evaluate the effect of immediate postoperative extubation and postoperative ventilation after minimally invasive direct coronary artery bypass (MIDCAB) surgery and to assess the role of epidural anesthesia.

DESIGN

Randomized prospective study.

SETTING

University hospital, single institution.

PARTICIPANTS

Patients (n = 90) scheduled for elective MIDCAB surgery.

INTERVENTIONS

Patients were divided into 3 groups: 30 patients had general anesthesia and were extubated immediately after surgery (extubated group), 30 patients had a thoracic epidural and general anesthesia and were extubated immediately after surgery (epidural group), and 30 patients had general anesthesia and were ventilated after surgery (intubated group).

MEASUREMENTS AND MAIN RESULTS

With a similar cardiac index and less vasoactive medication, mean arterial blood pressure (77 plus minus 8 mmHg [mean plus minus SD]) and heart rate (76 plus minus 10 beats/min) in the epidural group were lower on the first postoperative day than in the intubated group (83 plus minus 10 mmHg and 81 plus minus 13 beats/min) and the extubated group (86 plus minus 10 mmHg and 83 plus minus 13) (p = 0.01 and p = 0.09). Oxygenation on the first postoperative day was better in the epidural group than in the intubated group (14.8 plus minus 3.8 kPa v 12.6 plus minus 3.2 kPa; p = 0.05). The epidural group and the extubated group had a transient respiratory acidosis postoperatively. Pain score in the epidural group was lower on the first postoperative day than in the extubated group with general anesthesia (3.0 plus minus 1.6 visual analog scale v 4.6 plus minus 1.8 visual analog scale; p = 0.01). Hospital stay was shorter in the epidural group than in the ventilated group (5.9 plus minus 2.4 days v 8.1 plus minus 5.3 days; p = 0.05)

CONCLUSION

Immediate postoperative extubation in patients with thoracic epidural anesthesia and supplemental general anesthesia provides the most favorable clinical circumstances after MIDCAB surgery.

Hemodynamic changes with right lateral decubitus body positioning in the tilted porcine heart

BACKGROUND

In beating-heart coronary surgical procedures, exposure of posterior vessels through sternotomy causes cardiac function to deteriorate. We hypothesized that turning the subject to the right lateral decubitus position before cardiac retraction improves exposure of posterior vessels and preserves cardiac pump function on displacement.

METHODS

Eight 80-kg open-chest pigs were instrumented with catheter-tip manometers. After a stepwise 60-degree turn to the right lateral decubitus position of the body, the heart was retracted anteriorly to 90 degrees with a suction stabilizer.

RESULTS

Right lateral body positioning caused an approximately 45-degree right deviation of the apex, thereby exposing the left atrial groove. Stroke volume, mean arterial pressure, right atrial pressure, and right ventricular end-diastolic pressure increased to 106% +/- 5% (mean +/- standard error of the mean, p = 0.31), 106% +/- 3% (p = 0.01), 129% +/- 8% (p = 0.001), and 171% +/- 14% (p = 0.002), respectively, compared with control values. In contrast, left atrial pressure decreased to 73% +/- 6% (p = 0.007), whereas left ventricular preload remained unchanged (110% +/- 8%, p = 0.26). Additional anterior displacement to 90 degrees fully exposed the posterior vessels, and stroke volume decreased to 90% +/- 3% (p = 0.01) and mean arterial pressure to 93% +/- 5% (p = 0.07) at the expense of further increased right ventricular preload (256% +/- 28%, p < 0.001).

CONCLUSIONS

By placing the subject in the right lateral decubitus position, exposure through sternotomy of posterior vessels in the beating porcine heart was facilitated while mean arterial pressure was maintained.

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.

Early outcome after off-pump versus on-pump coronary bypass surgery: results from a randomized study

BACKGROUND

The use of cardiopulmonary bypass during coronary artery bypass surgery (CABG) has been associated with substantial morbidity. The recent introduction of cardiac stabilizers facilitates CABG without cardiopulmonary bypass (off-pump CABG), but it is unknown whether cardiac outcome after off-pump surgery is similar to that for the on-pump procedure.

METHODS AND RESULTS

In a multicenter trial, 281 patients (mean age 61 years, SD 9 years) were randomly assigned to off-pump or on-pump CABG. In-hospital results and cardiac outcome and quality of life after 1 month are presented. Cardiac outcome was defined as survival free of stroke, myocardial infarction, and coronary reintervention. The mean numbers of distal anastomoses per patient were 2.4 (SD 1.0) and 2.6 (SD 1.1) in the off-pump and on-pump groups, respectively. Completeness of revascularization was similar in both groups. Blood products were needed during 3% of the off-pump procedures and 13% of the on-pump procedures (P<0.01). Release of creatine kinase muscle-brain isoenzyme was 41% less in the off-pump group (P<0.01). Otherwise, no differences in complications were found postoperatively. Off-pump patients were discharged 1 day earlier. At 1 month, operative mortality was zero in both groups, and quality of life had improved similarly. In both groups, 4% of the patients had recurrent angina. The proportions of patients surviving free of cardiovascular events were 93.0% in the off-pump group and 94.2% in the on-pump group (P=0.66).

CONCLUSIONS

In selected patients, off-pump CABG is safe and yields a short-term cardiac outcome comparable to that of on-pump CABG.

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.

Does isoflurane optimize myocardial protection during cardiopulmonary bypass?

OBJECTIVE

To investigate the possible myocardial protective effect of isoflurane during aortic cross-clamp and cardioplegic cardiac arrest in patients undergoing conventional coronary artery bypass graft surgery.

DESIGN

Prospective, randomized.

SETTING

University medical center.

PARTICIPANTS

Forty-nine patients undergoing elective coronary artery bypass graft surgery divided into 2 groups: control group (n = 21) and isoflurane group (n = 28).

INTERVENTION

Isoflurane was administered in the pre-cardiopulmonary bypass (CPB) period to the isoflurane group.

MEASUREMENTS AND MAIN RESULTS

Hemodynamics and ST- segment variations were monitored in the pre-CPB period and after weaning from CPB in both groups. Incidence of reperfusion arrhythmias after release of aortic cross-clamp was compared. In the isoflurane group, the mean cardiac index after CPB was significantly higher than the pre-CPB value, whereas no difference between the 2 values was found in the control group. The higher cardiac index in the isoflurane group was associated with a lesser degree of ST- segment changes than in the control group. There was no significant difference between the 2 groups in the incidence of reperfusion arrhythmias after release of aortic cross-clamp.

CONCLUSION

The present report suggests that administration of isoflurane before aortic cross-clamping in patients undergoing coronary artery bypass graft surgery may optimize the myocardial protective effect of cardioplegia. Isoflurane may be particularly advantageous whenever prolonged periods of aortic cross-clamping or inadequate delivery of cardioplegia is expected.

Ultra-fast-track anesthetic technique facilitates operating room extubation in patients undergoing off-pump coronary revascularization surgery

OBJECTIVE

To determine if implementation of ultra-fast-track anesthetic (UFTA) technique facilitates operating room extubation in patients undergoing off-pump coronary artery bypass graft (CABG) surgery.

DESIGN

Retrospective review.

SETTING

Referral center for cardiovascular surgery at a university hospital.

PARTICIPANTS

Thirty-seven patients undergoing off-pump CABG surgery.

INTERVENTIONS

Two groups represented UFTA (n = 10) and standard anesthetic (controls, n = 27) techniques. Anesthesia was conducted with propofol, remifentanil, vecuronium, and thoracic epidural analgesia in the UFTA group and thiopental, fentanyl, pancuronium, and isoflurane in the control group. Active temperature control was an integral part of the UFTA technique but not the standard technique. The active temperature control included intravenous fluid warmer, prewarmed skin preparation, humidified inspired gases, a circulating water warming blanket, and a forced-air warmer, along with the maintenance of the operating room temperature at 24 degrees C. The control group was managed with an intravenous fluid warmer, and the ambient temperature remained constant (20 degrees C). Patients who did not satisfy extubation criteria within 30 minutes from the end of surgery were sedated and transferred to the intensive care unit (ICU).

MEASUREMENTS AND MAIN RESULTS

All patients in the UFTA group and 2 in the control group were extubated in the operating room immediately after surgery. None of the patients required reintubation. There was no significant difference in postextubation PaO(2) and PaCO(2) between the groups. Nasopharyngeal temperature decreased from 36.7 +/- 0.4 degrees C to 36.4 +/- 0.3 degrees C in the UFTA group and from 36.6 +/- 0.5 degrees C to 35.6 +/- 0.4 degrees C in the control group (p < 0.0001). Bradycardia occurred significantly more often in the UFTA group but there was no difference in episodes of hypotension. There were no perioperative deaths. Patients who were extubated in the operating room required lower nurse-to-patient acuity ratio (1:2) in the ICU. No difference was found in ICU and hospital length of stay.

CONCLUSIONS

Implementation of UFTA technique provided adequate hemodynamic control and facilitated operating room extubation in all patients. The impact of UFTA on earlier patient discharge and actual cost savings within a fully integrated post-cardiac surgery unit requires further evaluation.

Hemodynamic effects of elevation and stabilization of the heart during off-pump coronary surgery

BACKGROUND

Coronary artery bypass grafting (CABG) surgery is now being performed without the use of cardiopulmonary bypass (CPB). To achieve complete myocardial revascularization off-CPB, a technique has been developed to expose target coronary arteries while hemodynamics are maintained.

METHODS

Complete myocardial revascularization was performed in 18 consecutive patients. Exposure of target coronary arteries was achieved by a "single-suture" technique, placed in the oblique sinus of the pericardium. Traction on the suture elevates and rotates the heart, thereby exposing all target coronary arteries. Cardiac index (CI) and intracardiac pressures were measured with a Swan-Ganz catheter during the different phases of the operation.

RESULTS

All patients were successfully operated on without CPB. There were no postoperative complications or deaths. There were no major hemodynamic changes during the different stages of the operation; in other words, CI was unchanged during elevation of the heart and snaring of the main coronary branches. Pulmonary artery wedge pressure (PAWP) increased markedly during occlusion and stabilization of the circumflex coronary artery (p < 0.05). A marked increase in CI and cardiac output (CO) from baseline values was also recorded before chest closure (p < 0.05).

CONCLUSION

Complete myocardial revascularization can be achieved safely without CPB. The single-suture technique allows for exposure of all target coronary arteries without hemodynamic compromise.

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

OBJECTIVE

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

DESIGN

Retrospective nonrandomized analysis.

SETTING

Tertiary care hospital.

PARTICIPANTS

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

INTERVENTIONS

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

MEASUREMENTS AND MAIN RESULTS

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

CONCLUSION

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

Analysis of hemodynamic changes during beating heart surgical procedures

BACKGROUND

Coronary artery bypass grafting on the beating heart causes significant hemodynamic compromise during displacement of the heart. The precise mechanisms causing altered hemodynamics have not been clearly understood. The purpose of this study was to define the hemodynamic changes caused by displacing the heart in patients undergoing beating heart surgical procedures.

METHODS

Forty-four patients (35 men, 9 women; mean age, 64.5 +/- 9.6 years) underwent off-pump coronary artery bypass grafting. The hemodynamic variables were collected before and after positioning the heart for anastomosis of the left anterior descending, circumflex, and posterior descending coronary arteries.

RESULTS

There was a significant increase in right ventricular end-diastolic pressure during positioning for all vessels, and in left ventricular end-diastolic pressure during positioning for the left anterior descending and circumflex coronary arteries. Positioning for the circumflex artery showed the largest increase of left and right ventricular end-diastolic pressure, resulting in the greatest hemodynamic compromise.

CONCLUSIONS

In the clinical setting of diseased human hearts, there is a biventricular contribution to altered hemodynamics. The increase of right ventricular end-diastolic pressure in all positions suggests that the major cause of hemodynamic changes is disturbed diastolic filling of the right ventricle, especially by direct ventricular compression.

Heart displacement during off-pump CABG: how well is it tolerated?

BACKGROUND

Heart displacement during off-pump coronary artery bypass grafting (CABG) is necessary to expose the anastomosic sites. We analyzed the hemodynamic changes in relation to the grafted arteries.

METHODS

The relationship between surgical exposure and hemodynamic management was assessed in 150 consecutive patients undergoing off-pump CABG utilizing the Octopus Tissue Stabilization System (Medtronic, Minneapolis, MN).

RESULTS

Surgical exposure by anterolateral thoracotomy showed no significant hemodynamic changes. Through sternotomy, stroke volume was significantly reduced by dislocation at all target sites: by 6% at the left anterior descending artery (LAD), 25% at the diagonal branch artery (D), 14% at the right coronary artery (RCA), and 21% at the obtuse marginal artery (OM). The application of head-down positioning (LAD, 56%; D, 74%; RCA, 90%; OM, 96%) increased not only surgical exposure but also preload, producing correction of ventricular filling pressures and output. In a minority of cases, dopamine (3 to 5 microg x kg(-1) x min(-1)) was added to maintain baseline hemodynamic values (LAD, 5%; D, 15%; RCA, 7%; OM, 28%).

CONCLUSIONS

Revascularization during anterolateral thoracotomy was uneventful. The sternotomy approach with heart displacement induced right heart compression. Mainly fluid redistribution was sufficient to correct cardiac output. Once stabilized, systemic circulation remained unchanged during revascularization.