Experimental off-pump grafting of a circumflex branch via sternotomy using a suction device

Minimally invasive direct coronary artery bypass and off-pump coronary artery bypass surgery: anesthetic considerations

Many new surgical technologies are being developed, with the overall aim of improving outcomes. One common feature of many new technologies is that they offer a safer approach than previous techniques; one of the greatest forces for change over the last 30 years is risk reduction. Cardiac surgery risk has been effectively undercut by percutaneous-based procedures, which have offered dramatic reductions in risk--at least in the short term. Beating heart techniques, whether minimally invasive direct coronary artery bypass (MIDCAB), off-pump coronary artery bypass surgery (OPCAB), or in other forms, such as percutaneous valve replacement, are likely to dramatically increase over the next decade. What role OPCAB and MIDCAB techniques will play in this new era is anyone's guess.

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.

Acute effects of beating heart coronary surgery on left ventricular performance

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Mechanisms of hemodynamic changes during off-pump coronary artery bypass surgery

PURPOSE

To describe the mechanisms of hemodynamic changes during off-pump coronary artery bypass graft surgery (OP-CABG).

SOURCE

Pertinent medical literature in the English and French languages was identified through a Medline computerized literature search and a manual search of selected articles, using off-pump coronary artery surgery, beating heart surgery, hemodynamic, and transesophageal echocardiography as key words. Human and animal studies were included.

PRINCIPAL FINDING

Hemodynamic variations in OP-CABG may be due to mobilization and stabilization of the heart, or myocardial ischemia occurring during coronary occlusion. Suction type and compression type stabilizers produce hemodynamic effects through different mechanisms. Heart dislocation (90 degrees anterior displacement) and compression of the right ventricle to a greater extent than the left ventricle are responsible for hemodynamic alterations when using suction type stabilizers. Compression of the left ventricular outflow tract and abnormal diastolic expansion secondary to direct deformation of the left ventricular geometry are proposed mechanisms for hemodynamic derangements with compression type stabilizer. Coronary occlusion during the anastomosis can have additional effects on left ventricular function, depending on the status of collateral flow. The value and limitations of electrocardiographic (ECG), hemodynamic and echocardiographic monitoring modalities during OP-CABG are reviewed.

CONCLUSIONS

In summary, hemodynamic changes which can either be secondary to the stabilization technique or to transient ischemia represent an important diagnostic challenge during off-bypass procedures. The mechanism can vary according to the stabilization system. Current monitoring such as ECG and hemodynamic monitoring are used but remain limited in establishing the cause of hemodynamic instability. Transesophageal echocardiography is used in selected patients to diagnose the etiology of hemodynamic instability and can direct therapy, particularly in those with severe myocardial systolic and diastolic dysfunction, mild to moderate mitral regurgitation, or for patients who are unstable during the procedure.

Conversion to off-pump coronary bypass without increased morbidity or change in practice

BACKGROUND

This article examines the feasibility of complete conversion from conventional coronary artery operation to routine off-pump coronary bypass operation.

METHODS

Data on our first 285 off-pump procedures using the Octopus system (Medtronic Inc, Minneapolis, MN) represent our learning curve. This is a complete experience in coronary bypass surgery over 16 months.

RESULTS

The cohort was nonselected. All patients had at least two-vessel disease. Eight hundred seven grafts were performed (mean, 2.8 per patient) of which 647 grafts (84%) were arterial (mean, 2.3 per patient). One hundred seventy nine patients (63%) underwent total arterial revascularization. Eight patients required cardiopulmonary bypass; all other operations were completed off-pump. Complications were: mortality, 3 patients (1.5%); renal failure, 24 patients (8%); stroke, 2 patients (< 1%); and atrial fibrillation, 60 patients (21%). The morbidity data and frequency of arterial grafting did not differ from that of 355 patients who underwent coronary bypass operations in a preceding 18-month period.

CONCLUSIONS

Complete shift from routine use of cardiopulmonary bypass to nonselective off-pump coronary bypass operation is possible with a low conversion rate and without an apparent increase in morbidity or change in technique. Whereas short-term safety and efficacy seem certain, studies of long-term outcome are necessary before the eventual role of off-pump coronary bypass in myocardial revascularization can be defined.

Assessment of myocardial injury by troponin T in off-pump coronary artery grafting and conventional coronary artery graft surgery

PURPOSE

The present study was undertaken to assess the degree of myocardial injury, using troponin T (TnT), in off-pump coronary artery surgery (OPCAB) and in a comparable patient group undergoing conventional coronary artery graft surgery (CABG).

METHODS

Twenty-seven OPCAB and 27 CABG patients were investigated. Blood samples for TnT were taken at intubation and at 12, 24 and 72 h. Nine patients (five OPCAB, four CABG) underwent 2 h sampling for 12 h for the assessment of the TnT release profile. All patients had an electrocardiogram performed preoperatively and on the mornings of days 1 and 5 postoperatively.

RESULTS

The OPCAB group had significantly greater Canadian Heart Classification 3 patients (P = 0.003); however, other demographic data were similar between the two groups. All patients had normal TnT at initial sampling. The mean number of grafts in each group was 1.8 +/- 0.6 for OPCAB and 1.9 +/- 0.3 for CABG (P = NS). There were two new Q wave myocardial infarctions in the CABG group and none in the OPCAB group. These cases were excluded from biochemical analyses. Troponin T release was significantly less in the OPCAB group at 12 and 24 h (P < 0.001 and P = 0.03, respectively). Peak TnT release occurred at 6-8 h in both groups. Troponin T release was significantly lower in the OPCAB group at 2, 4, 6, 8, 10 and 12 h (P = 0.01, P = 0.03, P = 0.02, P = 0.02, P = 0.03 and P = 0.04, respectively). Postoperatively, the OPCAB group required less blood transfusion (P = 0.02).

CONCLUSIONS

The OPCAB group demonstrated a significantly reduced TnT release profile compared with the CABG group.

The Octopus Study: rationale and design of two randomized trials on medical effectiveness, safety, and cost-effectiveness of bypass surgery on the beating heart

The Octopus Study consists of two multicenter randomized clinical trials in which coronary artery bypass grafting on the beating heart (off-pump CABG) using the Utrecht Octopus Method is compared to intracoronary stent implantation and conventional CABG. The primary endpoint in the comparison of off-pump CABG versus stent implantation (OctoStent Trial) is medical effectiveness (i.e., absence of reintervention and major adverse cardiac and cerebrovascular events at 1 year after treatment). The primary endpoint in the comparison of off-pump CABG versus conventional CABG (OctoPump Trial) is cerebral safety (i.e., absence of cognitive deficits and cerebrovascular events at 3 months after treatment). Secondary endpoints in both trials include presence and severity of angina, quality of life, exercise capacity, and cost-effectiveness. A total of 560 patients will be enrolled. A random sample of 210 patients will undergo repeat angiography at 1 year to assess angiographic restenosis rate and graft patency. Including 1-year follow-up, the study will last for 3 years. Control Clin Trials 2000;21:595-609

Coronary artery bypass grafting using a miniature right ventricular support system

Cardiopulmonary bypass (CPB) with cardioplegic myocardial preservation has long been the gold standard for surgical care of coronary artery disease. More recently, alternatives to the conventional approach of CPB-myocardial revascularization have been developed. Epicardial stabilizing devices have been used to immobilize areas of the beating heart to provide a stable surface for some coronary anastomoses. These approaches are often limited to anterior aspects of the heart because revascularization of posterior and lateral vessels often requires the heart to be manipulated or contorted. Excessive manipulation can lead to hemodynamic compromise as a result of partially obstructing pulmonary blood flow. A miniature extracorporeal system has been developed that uses right ventricular support and allows for epicardial surgical procedures to be conducted on a beating heart without standard CPB. The extracorporeal system consists of a coaxial atrial cannula that is connected to a miniature centrifugal pump. Blood is drained from the right atrium, passes through the miniature centrifugal pump and is delivered through the cannula's inner reinfusion lumen into the pulmonary artery. The entire circuit volume is approximately 30 ml. The system is positioned on the sterile operative field. The pump is controlled by a console positioned adjacent to the patient. The centrifugal pump is capable of delivering blood flow at rates of 1-6 l/min. This extracorporeal system may be of benefit in maintaining adequate cardiac output during epicardial beating heart surgery.

Right heart mini-pump bypass for coronary artery bypass grafting: experimental study

BACKGROUND

Visualization of the left circumflex arteries during off-pump coronary artery bypass grafting (CABG) causes hemodynamic disturbance. We investigated whether right heart mini-pump bypass (RHB), using a centrifugal pump, improved the safety of this procedure by studying the influences of different heart displacement positions, the Trendelenburg maneuver and RHB on hemodynamics.

METHOD

Hemodynamic parameters in eight mongrel dogs (15.5-20 kg) were continuously monitored at a fixed heart rate of 80 beats/min through a conventional median sternotomy. The posterior descending artery (PDA) and left circumflex artery (LCX) were exposed using an Octopus tissue stabilizer. After evaluating the influence of the Trendelenburg maneuver on hemodynamics, a heparin-coated centrifugal pump without an oxygenator was introduced and the impact of different pump flow volumes was investigated during RHB.

RESULTS

LCX exposure caused significant decreases in aortic flow (to 35. 1+/-12.8%) and arterial mean pressure (to 66.1+/-9.3%) compared with baseline (P<0.001). In contrast to PDA exposure, values remained significantly decreased during the Trendelenburg maneuver. On the contrary, RHB significantly improved the hemodynamic impairments caused by both heart displacement procedures, especially LCX exposure, although 100% pump flow significantly increased left atrial pressure to 131.3+/-19.5% (P<0.01).

CONCLUSION

Exposure of the LCX caused severe hemodynamic deterioration, which was not fully reversed by the Trendelenburg maneuver. In contrast, RHB significantly improved hemodynamics, and therefore this technique can be beneficial for CABG of LCX in the limited cases.

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.

The enabler right ventricular circulatory support system for beating heart coronary artery bypass graft surgery

BACKGROUND

Beating heart coronary artery bypass graft surgery of the left anterior descending, diagonal, and right coronary artery can be performed safely with the Octopus Stabilization System. However, tilting of the heart, which is necessary to reach the obtuse marginal and distal right coronary arteries, causes hemodynamic instability. This study was performed to investigate the possible role of the Enabler right ventricular circulatory support system in counteracting this instability.

METHODS

In 8 sheep, the Enabler cannula was introduced via the jugular vein and positioned with the inlet valve in the right atrium and outlet valve in the pulmonary artery. The Octopus was used to expose the inferior wall and the posterior wall of the left ventricle. The hemodynamic effects of this tilting with and without Enabler right ventricular support were recorded, including Pressure Volume (PV) loops measured by conductance catheters in both ventricles.

RESULTS

Tilting caused a reduction in stroke volume (inferior 31%, posterior 17%) and Enabler activation increased stroke volume (inferior 13%, posterior 31%).

CONCLUSIONS

Tilting the heart has severe hemodynamic consequences that can be partially counteracted by the use of the Enabler for right ventricle support.

Off-pump revascularization of the circumflex artery: technical aspect and short-term results

BACKGROUND

Beating heart surgery is a technique currently used for revascularization of the anterior and inferior territory. However, revascularization of the circumflex artery is more problematic. With a specific apparatus and surgical technique, we have extended the use of beating heart surgery to more than 90% of patients with multivessel disease, including those necessitating circumflex artery revascularization.

METHODS

Between October 1996 and November 1997, 140 patients underwent beating heart surgery by the same surgeon (R.C.). Among these patients, 111 required reconstruction of the circumflex artery territory and were followed up prospectively. They represent the cohort of patients presented in this study. There were 90 men and 21 women averaging 64+/-9.9 years of age. Mean left ventricular ejection fraction was 55%+/-13.7%, and a significant left main coronary artery disease was present in 27% of the patients. Five patients had prior coronary revascularization.

RESULTS

An average of 3.1+/-0.1 grafts/patient were performed. Complete revascularization was achieved in 95%. Only 1 patient needed conversion to cardiopulmonary bypass because of spontaneous ascending aortic dissection. Perioperative and postoperative bleeding were 446+/-245 mL and 644+/-442 mL, respectively. Homologous transfusions were required in 40% of the patients. Myocardial infarction occurred in 2.7% and operative mortality in 0.7% (1 patient). Average hospital stay was 6.6+/-3.1 days, and no patient exhibited early recurrence of angina. Early coronary angiograms (first 8 patients) demonstrated a 100% patency with 95% freedom from significant stenosis.

CONCLUSIONS

Complete coronary artery revascularization is feasible on the beating heart without the assistance of cardiopulmonary bypass with a low morbidity and mortality and excellent early angiographic results. Long-term follow-ups are needed to substantiate the potential long-term benefits of this technique.

Angiographic results after minimally invasive coronary bypass grafting using the minimally invasive direct coronary bypass grafting (MIDCAB) approach

OBJECTIVE

The aim of the study was to evaluate the early and mid-term angiographic results after minimally invasive coronary bypass grafting using an 'off-pump' technique via a lateral minithoracotomy.

METHODS

In 221 out of 271 patients (81.5%) who underwent minimally invasive direct coronary bypass grafting (MIDCAB) the quality of the internal thoracic artery (ITA)-graft and the anastomosis was evaluated by conventional coronary angiography between the 2nd and 6th postoperative day (POD). A subgroup of 130 patients (47.9%) of the initial cohort were repeatedly controlled by angiography 6 months later.

RESULTS

The early postoperatively patency rate of the grafts was (96.8%). Moderate anastomotic stenosis between 50 and 75% was found in 13/221 (5.8%) patients, whereas severe stenosis of more than 75% was seen in 10/221 (4.5%) and occlusion of the graft in 3/221 (1.3%) patients. A stress-ECG was performed in patients with a severe stenosis to provoke ST-segment changes or clinical findings of myocardial ischemia. A positive stress test was found in 4/221 patients (1,8%). Early re-intervention was required in 7/221 (3.1%) patients. After 6 months, angiographic follow-up revealed a patency rate of (95.4%). Of 130 patients 5 (3.8%) presented with moderate anastomotic stenosis, whereas 3/130 (2.0%) patients showed a severe stenosis with one patient (0.7%) having myocardial ischemia during stress test. Occlusion of the graft was seen in 3/130 patients (2.3%). During follow-up, 4/130 (3.0%) patients underwent re-intervention. A comparison between early postoperative and 6-months angiogram revealed a decrease or a disappearance of the severity of the stenosis in 4/15 patients (26.6%).

CONCLUSION

Since stenosis of the anastomosis may occur after minimally invasive, beating heart coronary bypass grafting, postoperative angiography should be performed to provide quality control and to guide appropriate further treatment. The latter is necessary if the stenosis is accompanied by reduced run-off and evidence of myocardial ischemia during stress test. An improvement of early stenosis at the anastomosis may be expected in more than 25%.

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

OBJECTIVE

To describe hemodynamic alterations during coronary artery bypass grafting (CABG) without extracorporeal circulation using the Octopus Tissue Stabilizer, and to describe the two anesthetic management protocols based on either general anesthesia with opioids (34 patients) or general anesthesia with high thoracic epidural anesthesia (TEA; 66 patients).

DESIGN

A prospective observational report.

SETTING

An academic university heart center.

PARTICIPANTS

First 100 patients undergoing CABG using the Octopus Tissue Stabilizer.

INTERVENTIONS

None.

MAIN RESULTS

Current management provided satisfactory results in preventing hypoperfusion of the heart and inadequate systemic circulation without the use of major pharmacologic interventions. Movement of the heart to reach the target site of anastomosis caused hemodynamic alterations. These could easily be corrected by anesthetic interventions, such as fluid load and low doses of inotropes. High TEA allows earlier extubation compared with the opioid anesthesia technique (0.9 v 4.5 hours). Perioperative management and the incidence of postoperative complications did not differ between anesthetic techniques. Major complications, such as death, intraoperative myocardial infarction, and stroke, did not occur.

CONCLUSION

Both anesthetic protocols are safe and effective in handling these patients. Off-pump CABG surgery requires anesthetic interventions because hemodynamic alterations are caused by the presentation of the heart to the surgeon. The complication rate is low but needs to be evaluated, compared with conventional CABG, in a prospective randomized study. High thoracic epidural anesthesia allows early recovery, but improved outcome could not be proved in this patient group.

Favorable scanning electron microscopic findings of stapled saphenous vein-carotid artery anastomoses

BACKGROUND

In the progress toward "off-pump" endoscopic coronary artery surgical procedures, new techniques for coronary artery anastomoses are being developed. One such approach is the use of nonpenetrating titanium clips. We evaluated the quality of anastomoses achieved using this technique in a porcine model of saphenous vein-carotid artery grafting using scanning electron microscopy.

METHODS

Bilateral saphenous vein-carotid artery interposition grafts were implanted in 10 "white race" pigs, using the nonpenetrating clips in one side of the neck and conventional hand suturing on the opposite side. One week after operation, the grafts were harvested.

RESULTS

All grafts were patent 7 days after operation, and 40 anastomoses underwent scanning electron microscopic study. In all samples, the luminal surfaces of both the carotid artery and vein graft were covered by a continuous layer of endothelial cells up to the anastomosis. Anastomotic sites in all clipped samples and most of the sutured anastomoses were completely endothelialized, and anastomotic clefts were indistinguishable. However, in 25% of sutured specimens, the suture material remained clearly visible inside the lumen of the vessel, and the subendothelial matrix remained exposed, with extensive fibrin, red blood cells, and platelet deposition on its surface.

CONCLUSIONS

Because the endothelial coverage consistently appeared to be complete and the subendothelial matrix was not exposed, it is likely that the risk of early anastomotic thrombosis is reduced by using the nonpenetrating titanium clips.

Improved visualization in minimally invasive coronary bypass grafting

A special surgical technique is required for minimally invasive coronary artery bypass grafting, particularly under beating-heart conditions. We describe a very simple system that provides improved visualization of the surgical site.

Minimally invasive coronary artery bypass grafting without cardiopulmonary bypass: early experience and follow-up

BACKGROUND

There is renewed interest in coronary artery bypass grafting without cardiopulmonary bypass using the anterolateral minithoracotomy approach. We evaluated 209 patients who underwent minimally invasive direct coronary artery bypass grafting using an anterolateral minithoracotomy. The anastomosis was performed under direct vision on the beating heart without using cardiopulmonary bypass.

METHODS

The procedure was performed using a 6- to 9-cm left (or right) anterolateral thoracotomy for internal thoracic artery graft harvesting and anastomosis. Different devices were used for local immobilization. In 195 patients a single internal thoracic artery to left anterior descending coronary artery bypass was performed, in 3 patients a single right internal thoracic artery to right coronary artery bypass, and in 11 patients the radial artery was used together with the internal thoracic artery as a T-graft.

RESULTS

Conversion to sternotomy or cardiopulmonary bypass was necessary in 10 (4.7%) patients. Intraoperative myocardial infarction was observed in 4 patients (1.9%). Early postoperative redo operation was necessary in 5 patients (2.4%). Mortality was 0.47%. Postoperatively, 191 patients (91.3%) underwent angiography for graft patency control. The overall patency rate was 97.3%. Minor stenosis of the internal thoracic artery graft was observed in 18 patients (9.4%); moderate stenosis was observed in 5 patients (2.6%). Midterm angiographic follow-up after 6 months was performed in 58 patients. The patency rate was 98.2%. One patient with severe symptomatic stenosis (1.7%) underwent reoperation.

CONCLUSIONS

With the help of the local immobilization systems off-pump coronary artery bypass grafting was safely performed through a minithoracotomy. The incidence of intraoperative and postoperative complications was low and follow-up showed good results. Thus, minimally invasive direct coronary artery bypass grafting is an excellent technique for arterial revascularization in patients having symptomatic left anterior descending coronary artery disease.

Off-pump coronary bypass grafting: how to use the Octopus Tissue Stabilizer

Off-pump coronary artery bypass grafting requires immobilization of the coronary artery. A suction device (Octopus Tissue Stabilizer), attached to the epicardium and connected rigidly to the operating table rail, was used through limited and full surgical access for single-vessel and multivessel arterial revascularization, respectively. An outline for its application, as used by us to construct 122 anastomoses in 70 patients, including posterior wall grafting (in 9 patients) and sequential grafting on the anterior wall (in 17 patients), is presented.

Coronary artery bypass grafting without cardiopulmonary bypass using the octopus method: results in the first one hundred patients

OBJECTIVE

Cardiopulmonary bypass and global cardiac arrest enable safe coronary artery bypass grafting but have adverse effects. In off-pump coronary bypass grafting, invasiveness is reduced, but anastomosis suturing is jeopardized by cardiac motion. Therefore the key to successful off-pump coronary bypass grafting is effective local cardiac wall stabilization.

METHODS

We prospectively assessed the safety and efficacy of the Octopus tissue stabilizer (Medtronic, Inc., Minneapolis, Minn.) in the first 100 patients selected for off-pump coronary bypass via full or limited surgical access. To immobilize and expose the coronary artery, two suction paddles (-400 mm Hg), fixed to the operating table-rail by an articulating arm, stabilized the anastomosis site.

RESULTS

One hundred forty-one grafts (96% arterial) were used to create 172 anastomoses (17% side-to-side), up to 4 per patient, on average 23 in the full access group (46 patients) and 1.2 in the limited access group (54 patients). Complications included conversion to cardiopulmonary bypass (2%), conversion from limited to full access (3%), myocardial infarction (4%), predischarge coronary reintervention (2%), and late coronary reintervention (1%). Median postoperative length of hospital stay was 4 days (limited access) or 5 days (full access). Rapid recovery allowed 96% of patients to resume social activities within 1 month. At the 6-month angiographic follow-up, 95% of anastomoses was patent. At the 2- to 22-month follow-up (mean, 13 months), 98 patients were in Canadian Cardiovascular Society class I and 2 patients were in class II.

CONCLUSION

These results suggest that off-pump coronary artery bypass grafting with the Octopus tissue stabilizer is safe. Early clinical outcome and patency rates warrant a randomized study comparing this methods with conventional coronary bypass grafting.

Vertical displacement of the beating heart by the octopus tissue stabilizer: influence on coronary flow

BACKGROUND

In beating heart coronary artery bypass graft operations, biventricular pump failure, as observed after exposure of the posterior circumflex branches by sternotomy, may originate from mechanical obstruction to coronary flow.

METHODS

Regional coronary blood flow was measured in 8 anesthetized, paced, beta-blocked pigs, and the beating heart was fully retracted.

RESULTS

Displacement decreased cardiac output from 4.8 +/- 1.1 L/min (mean +/- standard deviation) to 2.8 +/- 1.2 L/min (p < 0.001), a 42% +/- 6% decrease that resulted in a decrease in mean arterial pressure by 48% +/- 6% (mean +/- standard error of the mean; p < 0.001) and a reduction in coronary blood flow in the left anterior descending coronary artery, the right coronary artery, and the circumflex coronary artery by 34% +/- 6%, 25% +/- 8%, and 50% +/- 10%, respectively (all p < 0.05 versus baseline). Relative circumflex coronary artery flow was 20.1% +/- 8.3% lower than the combined relative value of left anterior descending coronary artery and right coronary artery flows (p = 0.046). Subsequent 20 degrees head-down tilt significantly increased ventricular preload pressures and restored cardiac output and mean arterial pressure as well as coronary blood flow.

CONCLUSIONS

It is inferred that coronary blood flow was not mechanically obstructed during anterior displacement of the porcine beating heart, because augmentation of preloads by the maneuver of Trendelenburg restored coronary flow parallel to the recovery of cardiac output and mean arterial pressure while the heart remained retracted by 90 degrees.

Full-spectrum cardiac surgery through a minimal incision: mini-sternotomy (lower half) technique

A technique is described in which most, if not all, cardiac operations may be performed through a standard small incision. A midline, lower half sternotomy is used. This provides traditional exposure of the heart and allows the surgeon to directly visualize the operating field and use familiar instruments. The complete spectrum of coronary revascularization and cardiac valve operations has been performed through this less-invasive incision.

Minimally invasive coronary artery bypass grafting: on the beating heart and via limited access

Minimally invasive coronary artery bypass grafting (MICABG) may be achieved by arterial grafting on the beating heart, without cardiopulmonary bypass, and by operations via limited access. The Second Utrecht MICABG Workshop held October 4-5, 1996, focused on beating-heart coronary immobilization, limited-access thoracoscopic and direct-vision mobilization of the internal mammary artery, limited-access left anterior descending coronary artery grafting, and, finally, facilitated distal anastomosis techniques. It has yielded 33 reports in this supplement. The combined, cumulative experience of a number of participants exceeded 3,000 beating-heart cases, including more than 1,000 with arterial grafting through limited access. The average number of anastomoses per patient ranged from 1.0 to 2.0. Therapeutic strategies are evolving, and dedicated instrumentation is being developed. Randomized clinical trials with angiographic follow-up are required to establish that the reduction in invasiveness of coronary bypass grafting is not achieved at the expense of suboptimal quality of the arterial graft and the distal anastomosis.