Paul F. Gründeman

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.

Exposure of circumflex branches in the tilted, beating porcine heart: echocardiographic evidence of right ventricular deformation and the effect of right or left heart bypass.

OBJECTIVE In off-pump coronary surgery, exposure of posterior vessels via sternotomy causes deterioration of cardiac function. Changes in ventricular geometry, valve competence, and hemodynamics after retraction of the beating heart were studied. Subsequently, the modifying effect of right or left heart bypass was investigated. METHODS In six 80-kg pigs, an ultrasound probe was attached to the backside of the left ventricle and the heart was fully retracted with a suction tissue stabilizer. Five pigs underwent additional pump support. RESULTS During retraction, the right ventricle was squeezed between the pericardium and interventricular septum, thereby decreasing its diastolic cross-sectional area by 62% +/- 6% (P <.001) while, concomitantly, right ventricular end-diastolic pressure increased to 165% +/- 19% (P =.004) of basal values. Stroke volume and mean arterial pressure decreased by 29% +/- 6% and 23% +/- 8% (P =.007 and P =.02, respectively). Left ventricular shape became somewhat elliptic without changes in preload pressure, and its diastolic cross-sectional area decreased by 20% +/- 3% (P =.001). All valves were competent. Right heart bypass restored left ventricular cross-sectional area, stroke volume, and mean arterial pressure. In contrast, left heart bypass increased blood pressure only marginally. CONCLUSIONS Ninety-degree anterior displacement of the beating porcine heart caused primarily right ventricular dysfunction as a result of mechanical interference with diastolic expansion without concurring valvular incompetence. Right heart bypass normalized stroke volume and mean arterial pressure by increasing left ventricular preload; in contrast, left heart bypass failed to restore systemic circulation.

Cyclooxygenase-2 Inhibition Increases Mortality, Enhances Left Ventricular Remodeling, and Impairs Systolic Function After Myocardial Infarction in the Pig

Background— Cyclooxygenase (COX)-2 expression in the heart increases after myocardial infarction (MI). In murine models of MI, COX-2 inhibition preserves left ventricular dimensions and function. We studied the effect of selective COX-2 inhibition on left ventricular remodeling and function after MI in a pig model. Methods and Results— Twenty-two pigs were assigned to COX-2 inhibition with a COX-2 inhibitor (COX-2i; celecoxib 400 mg twice daily; n=14) or a control group (n=8). MI was induced by left circumflex coronary artery ligation, and the animals were euthanized 6 weeks later. Cardiac dimensions and function were assessed with echocardiography and conductance catheters. Infarct size and collagen density were analyzed with triphenyltetrazolium chloride staining and picrosirius red staining, respectively. COX-2 inhibition increased mortality compared with controls (50% versus 0%, P=0.022), whereas infarct size was similar (13.1±0.7% versus 14.1±0.1%, P=0.536). The decrease in thickness of the infarcted myocardial wall was more pronounced in the COX-2i group (60.6±9.6% versus 36.2±5.7%, P=0.001). End-diastolic volume was higher in the COX-2i group (133.9±33.5 versus 91.1±24.0 mL; P=0.021), as was the end-systolic volume at 100 mm Hg (81.7±27.8 versus 56.3±21.1 mL; P=0.037), which indicates that systolic function was more severely impaired. Infarct collagen density was lower after COX-2i treatment (25.3±3.9 versus 56.1±23.8 gray value/mm2; P=0.005). Conclusions— In pigs, COX-2 inhibition after MI is associated with increased mortality, enhanced left ventricular remodeling, and impaired systolic function, probably due to decreased infarct collagen fiber density.

Minimally invasive coronary artery bypass grafting: an experimental perspective.

In their recent editorial “Minimally Invasive Coronary Bypass: A Dissenting Opinion,” Bonchek and Ullyot1 express concerns about ill-guided attempts to deviate from the conventional revascularization procedure that is “safe, effective, durable, reproducible, complete, versatile, and teachable.” In the present editorial, an experimental perspective on the search for less invasive surgical strategies is provided that will convey an opposite opinion. First, a brief reappraisal is warranted of the safety of coronary artery bypass graft surgery (CABG) during cardiac arrest supported by cardiopulmonary bypass (CPB). The great majority of CABG patients benefit greatly from coronary revascularization, but the surgical procedure is not without adverse effects. The Society of Thoracic Surgeons (STS) National Cardiac Surgery Database (January 1998) lists complications of 170 895 CABG-only operations, including 13 736 reoperations, performed in the United States in 1996. Operative mortality was 2.9% (2.5% in men, 4.0% in women). Operative mortality increases with age, from 1.1% at age 20 to 50 years to 7.2% at 81 to 90 years. In only 65.4% of procedures were no complications reported. Most complications are listed in the Table⇓. View this table: Table 1. Complications CABG-Only Patients in the United States, 1996 Another way to assess the clinical outcome of conventional CABG is to analyze hospital discharge data from health insurance records.2 Of 101 812 patients ≥65 years old operated on in January through October 1993 in the United States, 4.3% died in hospital. Of particular concern are patients (3.6%) who were discharged to a non–acute-care facility.3 Owing to complications, 10.2% were discharged late (>14 days) to home. Thus, 81.9% were discharged to home in ≤14 days. In the first 2 months after discharge to home, 0.7% died and 9.9% were readmitted for cardiovascular, respiratory, or cerebrovascular reasons. Although each of these numbers needs to be carefully interpreted in its …

A novel one-shot anastomotic stapler prototype for coronary bypass grafting on the beating heart: Feasibility in the pig ☆ ☆☆ ★

OBJECTIVE The nonpenetrating, arcuate-legged clip has proved its ability to provide a high-quality microvascular anastomosis. This study assessed the feasibility of constructing a coronary end-to-side anastomosis on the beating heart with a novel mechanical, sutureless anastomotic device that applies 12 circumferential clips simultaneously. METHODS In 14 consecutive pigs (70-90 kg), the left internal thoracic artery (diameter, 3 mm) was grafted to the left anterior descending coronary artery (diameter, 3 mm) by means of a one-shot anastomotic stapler prototype. Endothelial denudation, medial necrosis, and intimal hyperplasia were analyzed quantitatively and compared with those seen in conventionally sutured anastomoses (n = 4). RESULTS In 8 of 14 anastomoses, the one-shot anastomotic stapler successfully applied all 12 clips circumferentially across the everted arteriotomy edges. In the remaining, either 1 (n = 4) or 3 and 4 adjoining malaligned clips had to be replaced manually with a single-clip applicator. Coronary occlusion was limited to approximately 3 minutes. At follow-up, all anastomoses were patent angiographically. At 2 days, in 2 of 7 cases, a local coronary dissection was observed, and there was a considerable loss of endothelial cells and medial damage. At 28 days, however, minimal intimal hyperplasia was seen at the anastomotic lining, although more pronounced when compared with conventionally sutured anastomoses. CONCLUSIONS The one-shot anastomotic stapler prototype enabled short-occlusive (3 minutes), sutureless end-to-side grafting on the beating porcine heart. In spite of early endothelial and medial damage and 2 local dissections, all anastomoses remained patent with minimal intimal hyperplasia at 4 weeks.

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.

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.

Feasibility of Electroporation for the Creation of Pulmonary Vein Ostial Lesions

Feasibility of Electroporation. Introduction: There is an obvious need for a better energy source for pulmonary vein (PV) antrum isolation.

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 1×1 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. Conclusion—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.