High-frequency epicardial ultrasound: review of a multipurpose intraoperative tool for coronary surgery.

BACKGROUND: In open-chest coronary artery bypass grafting (CABG), the surgeon faces several intraoperative challenges: (1) to locate the target coronary artery, (2) to select the optimal anastomotic site, and (3) to assess the quality of the graft and distal anastomosis. Endoscopically, these three diagnostic aims are particularly challenging. METHODS: We reviewed the literature on the intraoperative application of high-frequency (6.5-15 MHz) epicardial ultrasound (ECUS) in CABG to aid in these challenges. RESULTS: Overall, ECUS was used in 628 patients to visualize and assess 912 (segments of) coronary arteries, as well as 418 grafts and distal anastomoses. In 96 cases, ECUS successfully located a coronary artery that was buried in the epicardial and/or myocardial tissue. In 37/155 (24%) imaged anastomotic sites, an alternative site free of pathology was selected. For quality assessment of the coronary anastomosis, experimental validation of ECUS included 218 anastomoses in ex vivo and animal models. ECUS showed high sensitivity (0.98) and specificity (1.00) for detection of anastomotic construction errors in 120 ex vivo anastomoses. In 418 grafts and distal anastomoses evaluated in patients, irregularities leading to revision were detected in 8 (1.9%) anastomoses and minor irregularities in an additional 23 (5.5%) anastomoses. However, little is known about the effect on long-term patency of specific anastomotic abnormalities revealed by ECUS. Scanning of arteries and anastomoses required several minutes. Current size ultrasound probes allowed successful experimental robot-assisted endoscopic application of ECUS. CONCLUSIONS: CABG may be facilitated and improved in several ways by intraoperative high-frequency epicardial ultrasound scanning. Totally endoscopic CABG may benefit from ultrasound diagnostics in particular.

Coronary connector devices: analysis of 1,469 anastomoses in 1,216 patients.

Automated coronary anastomotic devices could be the key to limited or port access procedures. To evaluate their clinical performance to date, 33 studies that included systematic elective angiographic imaging were reviewed, reporting on five proximal and seven distal devices. Marked outcome differences between the technologies were uncorrelated to study type and demographic, operative, and follow-up variables. Significant issues included graft thrombosis, graft kinking, and stenosing intimal hyperplasia inside the connector, limiting clinical applicability of at least three devices. Substantial equivalence to 1-year conventional anastomotic patency standards was found for selected anastomotic devices, which holds the promise of expanded applicability.

Cognitive outcomes five years after not undergoing coronary artery bypass graft surgery.

BACKGROUND: Patients with coronary artery disease who underwent coronary artery bypass graft surgery have a high risk of cognitive decline 5 years after the procedure. It is conceivable that this is not caused by the operation, but by natural aging. METHODS: Psychologists repeatedly administered a battery of seven neuropsychological tests with eight main variables to 112 subjects without known coronary artery disease, with a time interval of 5 years. Cognitive decline was defined as deterioration in performance beyond normal variation in at least two of the eight main variables. The incidence of cognitive decline in the control subjects was compared with the incidence of cognitive decline in the 281 participants of the Octopus Study, who underwent coronary artery bypass graft surgery 5 years earlier. Patients and control subjects were age-matched. RESULTS: After 5 years, cognitive outcome could be determined in 99 of 112 control subjects (88%) and 240 of 281 coronary artery bypass graft surgery patients (85%). Cognitive decline was present in 82 (34.2%) of 240 coronary artery bypass graft surgery patients and in 16 (16.2%) of 99 control subjects (crude odds ratio, 2.69; 95% confidence interval, 1.48 to 4.90). However, after correction for differences in age, sex, education, and baseline comorbidity between the patients and the control subjects, the odds ratio was 1.37 (95% confidence interval, 0.65 to 2.92). CONCLUSIONS: We were unable to demonstrate that patients who underwent coronary artery bypass graft surgery have more cognitive decline after 5 years than control subjects without coronary artery disease.

Cognitive and cardiac outcomes 5 years after off-pump vs on-pump coronary artery bypass graft surgery.

CONTEXT: Conventional coronary artery bypass graft surgery with use of cardiopulmonary bypass (on-pump CABG) is associated with excellent long-term cardiac outcomes but also with a high incidence of cognitive decline. The effect of avoiding cardiopulmonary bypass (off-pump CABG) on long-term cognitive and cardiac outcomes is unknown. OBJECTIVE: To compare the effect of off-pump CABG and on-pump CABG surgery on long-term cognitive and cardiac outcomes. DESIGN, SETTING, AND PARTICIPANTS: The Octopus Study, a multicenter randomized controlled trial conducted in the Netherlands, which enrolled 281 low-risk CABG patients between 1998 and 2000. Five years after their surgery, surviving patients were invited for a follow-up assessment. INTERVENTION: Patients were randomly assigned to receive either off-pump (n = 142) or on-pump (n = 139) CABG surgery. MAIN OUTCOME MEASURE: The primary measure was cognitive status 5 years after surgery, which was determined by a psychologist blinded to treatment allocation who administered 10 standardized validated neuropsychological tests. Secondary measures were occurrence of cardiovascular events (all-cause mortality, stroke, myocardial infarction, and coronary reintervention), anginal status, and quality of life. RESULTS: After 5 years, 130 patients were alive in each group. Cognitive outcomes could be determined in 123 and 117 patients in the off-pump and on-pump groups, respectively. When using a standard definition of cognitive decline (20% decline in performance in 20% of the neuropsychological test variables), 62 (50.4%) of 123 in the off-pump group and 59 (50.4%) of 117 in the on-pump group had cognitive decline (absolute difference, 0%; 95% confidence interval [CI], -12.7% to 12.6%; P>.99). When a more conservative definition of cognitive decline was used, 41 (33.3%) in the off-pump group and 41 (35.0%) in the on-pump group had cognitive decline (absolute difference, -1.7%; 95% CI, -13.7% to 10.3%; P = .79). Thirty off-pump patients (21.1%) and 25 on-pump patients (18.0%) experienced a cardiovascular event (absolute difference, 3.1%; 95% CI, -6.1% to 12.4%; P = .55). No differences were observed in anginal status or quality of life. CONCLUSION: In low-risk patients undergoing CABG surgery, avoiding the use of cardiopulmonary bypass had no effect on 5-year cognitive or cardiac outcomes. TRIAL REGISTRATION: isrctn.org Identifier: ISRCTN69438133.

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.

S2 connector versus suture: distal coronary anastomosis remodeling, patency, and function in the pig.

BACKGROUND: Anastomotic connectors could be the key to less invasive bypass surgery, including endoscopic procedures, but equivalence to conventional suturing needs to be established. A novel distal coronary connector was tested pre-clinically for safety and efficacy in comparison to conventional suturing. METHODS AND RESULTS: Left internal thoracic to left anterior descending coronary artery bypasses were constructed off-pump in 35 pigs (73+/-8 kg). An intraluminal metal connector (S2AS) was used in 21 and conventional suturing in 14 animals. S2AS anastomosis construction was easier achieved in one-fourth of the conventional construction time (3.7+/-0.7 versus 16.5+/-2.6 minutes; P<0.001). Acute patency tended to be better (P=0.15). All anastomoses were evaluated intraoperatively, and subgroups at 90 and at 180 days. Patency was 100%. An effective remodeling response was observed in all groups, resulting in unobstructed anastomoses with excellent hemodynamic performance (fractional flow reserve > or = 0.93 at 180 days). At 6 months, the noncompliant connector was covered with stabilized neointima that was thinner than found on the suture line (0.10+/-0.04 versus 0.31+/-0.13 mm; P=0.01). The connector induced less lumen loss (-0.6+/-6.5 versus 21.6+/-19%; P=0.03). The initial side-to-side configuration had remodeled to an end-to-side shape as intended. CONCLUSIONS: In the porcine model, the connector rapidly and consistently produced high-quality anastomoses that fully met current standards on patency and function. Unconventional aspects like a noncompliant intraluminal ring and a side-to-side to end-to-side converted configuration did not interfere with favorable anastomosis remodeling. These findings shed a new light on the anatomical prerequisites for anastomosis patency.

Risk and determinants of myocardial injury during off-pump coronary artery bypass grafting.

Perioperative myocardial injury (PMI) after coronary revascularization (bypass surgery using cardiopulmonary bypass or percutaneous intervention) is strongly associated with future adverse events, such as death, myocardial infarction, and coronary intervention. The incidence, determinants, and prognostic significance of PMI after bypass surgery without cardiopulmonary bypass (off-pump surgery) are unknown. The study population comprised the patients who were randomized to off-pump surgery in the Octopus Study. PMI was defined by a creatine kinase isoenzyme-MB/total creatine kinase ratio of >5% during the first 48 hours, postoperatively. PMI occurred in 137 of 260 patients (52%). Using multivariate regression analysis, age, female gender, previous myocardial infarction, preoperative nitrate use, preoperative diuretic use, and number of grafts were independently associated with an increased risk of PMI during off-pump surgery. The presence of preoperative coronary collaterals showed a negative association with PMI. The occurrence of PMI had a crude odds ratio of 7.53 (95% confidence interval 1.59 to 35.63) for an adverse cardiac event at 1 year after off-pump surgery. This odds ratio changed little after adjustment for confounders (odds ratio 6.39, 95% confidence interval 1.41 to 28.93). In conclusion, more severe atherosclerotic disease and female gender were associated with an increased risk of perioperative myocardial injury during off-pump bypass surgery, although the presence of coronary collaterals appeared to be protective. Patients with perioperative myocardial injury during off-pump surgery were at a higher risk of adverse cardiac outcomes at 1 year.

Ultrasound mini-transducer with malleable handle for coronary artery surgery.

PURPOSE: A 13 MHz epicardial ultrasound mini-transducer (15 x 9 x 6 mm) with a custom made malleable handling tool was evaluated to assess the coronary artery and anastomosis on all sides of the heart. DESCRIPTION: On indication, in 8 patients undergoing coronary artery bypass surgery on the arrested heart, 8 coronary arteries as well as 27 coronary anastomoses were scanned. EVALUATION: The malleable handle was easily adjusted, and all sides of the heart were accessible for scanning with the mini-transducer. Based on intraoperative scanning, the anastomotic site was altered (n = 4), an additional coronary artery was grafted (n = 2), and the left anterior descending coronary artery was identified after incorrect conventional selection of the diagonal branch (n = 1). No anastomosis construction errors were detected. In one anastomosis, a calcified plaque was seen in the outflow corner. CONCLUSIONS: The epicardial ultrasound mini-transducer with its malleable handle allowed successful visualization and assessment of the coronary arteries and anastomoses on all sides of the heart. Ultrasound information greatly aided in intraoperative decision making that resulted in anastomotic site changes and prevented grafting of the wrong vessel.

Quality assessment of distal S(2)AS connector anastomosis by 13 MHz epicardial ultrasound.

OBJECTIVE: During application of a distal coronary bypass connector, we employed 13 MHz epicardial ultrasound to evaluate quantitative caliper measurements for vessel size matching and to assess anastomosis quality after connector deployment. METHODS: Two S(2)AS connector anastomoses were constructed on ex vivo pressure-perfused porcine hearts. Epicardial ultrasound measurements of the connector ring and anastomosis were compared to intravascular ultrasound measurement and cast dimensions. In 21 pigs, anastomotic sites with internal diameter of 2.25-3.0mm (internal mammary artery, IMA) and 1.8-2.2mm (left anterior descending coronary artery, LAD) were selected using external caliper and epicardial ultrasound measurements. Anastomoses were visualized and assessed intraoperatively (beating heart, n=21) and at 3 and 6 months' follow-up (explanted heart, n=10 each). RESULTS: Epicardial ultrasound underestimated connector dimension by < or =5% versus intravascular ultrasound and deviated < or =13% from cast dimensions for other anastomotic measurements. Caliper estimates of internal IMA and LAD diameter differed from ultrasound by -3+/-6% and -2+/-7% (mean+/-SD), respectively. Intraoperatively, the anastomotic orifice was flawless in all animals. It remained fully patent at 3 and 6 months by ultrasound, which was confirmed by histology. The connector to LAD percentage diameter stenosis changed from -12+/-5% intraoperatively to -1+/-7% at 3 months and from -5+/-6% intraoperatively to -16+/-13% at 6 months, in the growing pig model. CONCLUSIONS: In the pig, external caliper measurements provided a reliable quantitative estimate of inner graft and coronary diameter for connector size matching. Epicardial 13 MHz ultrasound is a promising method to assess coronary anastomosis quality even when connector metal is present.

Transmural differences in myocardial function and metabolism during direct left ventricular to coronary artery sourcing.

BACKGROUND: We investigated the hypothesis that in the absence of collateral circulation, a left ventricle-coronary artery (LV-CA) bypass will maintain normal LV wall function and metabolism transmurally, both at rest and during stress, when the left anterior descending coronary artery (LAD) is acutely occluded proximally. METHODS: In 18 anesthetized pigs (74 +/- 7 kg, mean +/- standard deviation), a covered stent was placed transmurally in the lateral wall of the beating LV and connected to the proximal LAD via an arterial graft. Subepicardial and subendocardial segmental shortening as well as interstitial lactate and glucose concentrations were measured regionally by sonomicrometry and microdialysis, respectively. RESULTS: When the LAD was occluded proximally, direct left ventricular sourcing decreased the net LAD flow to 64 +/- 25% of the native flow (n = 18, all animals). In the subepicardium, systolic shortening (SS) decreased to 87 +/- 18% of baseline (p = 0.124), with the appearance of minor postsystolic shortening (PSS), and minor changes in interstitial lactate and glucose levels. In the subendocardium, in contrast, SS decreased to 54 +/- 20% (p = 0.001). Marked PSS concurred with a sixfold increase in lactate (p = 0.008), and a 65 +/- 31% decrease in glucose (p = 0.003), indicating subendocardial anaerobic metabolism. Stress induced by infusion of dobutamine increased lactate and decreased glucose concentration in the subepicardium to subendocardial levels, indicating transmural anaerobic metabolism. CONCLUSIONS: In the anesthetized pig, direct sourcing by a LV-CA bypass distal to an acute coronary occlusion resulted in a 36% decrease in net forward coronary flow, subendocardial anaerobic metabolism, and loss of subendocardial contractile function at rest. These adverse effects extended into the subepicardium when the heart was stressed.

Detection of construction errors in ex vivo coronary artery anastomoses by 13-MHz epicardial ultrasonography.

OBJECTIVE: Intraoperative detection of suboptimal coronary anastomoses allows revision before chest closure. We evaluated an epicardial 13-MHz ultrasound minitransducer as a means to detect three different coronary anastomosis construction errors. METHODS: In total, 120 internal thoracic artery-to-coronary artery anastomoses were constructed correctly (n = 60) or incorrectly (n = 60) with one technical error: suture crossover, purse-string or deep toe stitch (n = 20 each). Anastomoses were performed on ex vivo pressure-perfused porcine (96 anastomoses) and human hearts (24 anastomoses). Two blinded observers scanned and scored the anastomoses with epicardial ultrasonography. In 24 human and 24 porcine anastomoses, angiograms were made of 24 correct and 24 incorrect anastomoses and scored by two other blinded observers. Angioscopy and cast injection served as a reference. RESULTS: Overall, 119 of 120 anastomoses were accurately scored as correct or incorrect within a median of 67 seconds (8-381 seconds) by both observers (sensitivity 0.98, specificity 1.00, kappa 1.00 (1.00, 1.00, and 1.00 in angiography subset, respectively). One deep toe stitch that induced outflow corner stenosis was spotted by both observers but regarded as insignificant and thus inaccurately scored as correct. In 5 anastomoses, unintended irregularities were detected. By angiography, anastomoses were accurately scored with a sensitivity of 0.75 and a specificity of 0.81 ( P < .001 vs ultrasonography) and kappa of 0.54. Angioscopy and cast confirmed ultrasonographic findings and did not reveal irregularities other than detected by ultrasonography. CONCLUSION: Ex vivo epicardial 13-MHz ultrasonography allowed rapid and accurate evaluation of coronary anastomoses and detected technical construction errors with higher sensitivity and specificity than angiography.

Role of coronary collaterals in off-pump and on-pump coronary bypass surgery.

BACKGROUND: Collaterals limit infarct size, preserve viability, and reduce mortality in patients with acute myocardial infarction. In patients with stable coronary disease, collaterals are associated with less angina and ischemia during angioplasty and fewer ischemic events during follow-up. The role of collaterals has not been studied in patients undergoing off-pump or on-pump bypass surgery. METHODS AND RESULTS: The population consisted of the 281 patients randomized to off-pump or on-pump CABG in the Octopus Study. Collaterals were defined on the baseline angiogram with the Rentrop score and were present in 49% and 51% of the patients in the off-pump and on-pump group, respectively. Perioperative myocardial infarction was defined by a creatine kinase-MB to CK ratio >10% and occurred in 18.2% in the off-pump group and 32.5% in the on-pump group. The unadjusted OR of perioperative myocardial infarction in the presence of collaterals was 0.31 (95% CI 0.17 to 0.84) in the off-pump group and 1.06 (95% CI 0.29 to 3.85) in the on-pump group After adjustment for age, gender, hypertension, hypercholesterolemia, diabetes, multivessel disease, ventricular dysfunction, incomplete revascularization, and ischemic time, the OR was 0.34 (95% CI 0.14 to 0.84) in the off-pump group and 1.28 (95% CI 0.30 to 5.40) in the on-pump group, respectively. Kaplan-Meier estimates of event-free survival at 1 year were 87% in patients with and 69% in those without collaterals after off-pump CABG. These estimates were 66% and 63%, respectively, after on-pump CABG. CONCLUSIONS: Collaterals protect against perioperative myocardial infarction during off-pump surgery but not during on-pump surgery and are associated with a better 1-year event-free survival.

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

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

Geometry assessment of coronary artery anastomoses with construction errors by epicardial ultrasound.

OBJECTIVE: There is concern about the quality of the distal anastomosis in off-pump coronary artery bypass grafting. We investigated the impact of specific construction errors on anastomotic geometry using epicardial ultrasound. METHODS: Twelve ex vivo pressure perfused porcine and five isolated post-mortem human hearts were used to construct 35 internal mammary artery to coronary artery anastomoses, either without (n = 7) or with a standardized construction error (oversutured toe, oversutured heel, cross-over or purse string; each error, n = 7). The anastomotic geometry was visualized and measured by a 13 MHz ultrasound mini-transducer. Impression cast material was used to validate anastomotic geometry. RESULTS: All 28 errors were visualized properly. Two unintended construction abnormalities were observed. In the porcine heart, the ratio of anastomotic orifice area and outflow corner area was 1.3+/-0.2 (mean+/-standard deviation) in the control group and reduced in the error groups: oversutured toe, 0.6+/-0.2 (P = 0.001 oversutured heel, 0.9+/-0.2 (P = 0.037); cross-over, 0.4+/-0.2 (P < 0.001); purse string, 0.3+/-0.2 (P < 0.001). None of the errors reduced the area of the inflow or outflow corner itself compared to the recipient coronary artery. In the human heart, all construction errors as well as wall plaque were visualized properly. In all anastomoses, ultrasound geometry corresponded to cast geometry. CONCLUSIONS: Ex vivo, epicardial 13 MHz ultrasound enabled accurate visualization and assessment of four different construction errors in the coronary anastomosis. All errors reduced the area of the anastomotic orifice, but not the inflow or outflow corner.

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.

Myocardial blood supply through a direct left ventricle-coronary artery shunt is not aided by augmented coronary capacitance.

OBJECTIVES: Left ventricle-coronary artery shunting is proposed as an alternative means of myocardial revascularization when standard methods are not an option. During diastole, however, regurgitant coronary flow to the left ventricle decreases the efficacy of the left ventricle-coronary artery shunt. We investigated whether augmented coronary compliance would improve net forward shunt flow. METHODS: In 11 anesthetized pigs a specially designed stent was placed through the lateral wall of the left ventricle. Through an arterial graft, it was connected to the proximal left anterior descending coronary artery. A blind stump of the right internal thoracic artery (15 cm) was anastomosed to the distal left anterior descending coronary artery to serve as added coronary compliance chamber. Blood flow was measured in the coronary artery just distal from the left ventricle-coronary artery shunt, as well as in the shunt and in the compliance chamber entrance-exit. RESULTS: The left ventricle-coronary artery shunt decreased the net forward midcoronary flow to 53% +/- 18% (mean +/- SD) of native flow (8 +/- 4 vs 16 +/- 5 mL/min at baseline, P <.01). The augmented compliance did not significantly increase net forward coronary flow (61% +/- 25% of native flow, P <.01 vs baseline and P =.21 vs left ventricle-coronary artery shunt with normal compliance). The increase in systolic forward flow (53 +/- 23 vs 37 +/- 19 mL/min with normal compliance) was accompanied by a similar increase in diastolic regurgitant flow (-26 +/- 20 vs -16 +/- 16 mL/min). CONCLUSION: In healthy pigs a left ventricle-coronary artery shunt decreased net forward coronary flow to 53% +/- 18% of native flow. Augmentation of coronary artery compliance did not improve shunt performance.

Endoscopic localization and assessment of coronary arteries by 13 MHz epicardial ultrasound.

BACKGROUND: In totally endoscopic coronary artery bypass grafting the target coronary artery is difficult to locate and assess. We explored the capacity of a high-frequency epicardial ultrasound mini-transducer (Aloka, Tokyo, Japan) to endoscopically locate and assess the left anterior descending (LAD), third obtuse marginal (OM3), and right posterior descending (RDP) coronary arteries. METHODS: In eight pigs, the LAD, OM3, and RDP were endoscopically exposed. The mini-transducer was manipulated by the "da Vinci" telemanipulation system (Intuitive Surgical, Inc, Mountain View, CA) over the unstabilized and stabilized epicardium to identify the target artery, obtain a scout scan, and both transverse and longitudinal images. RESULTS: In both unstabilized and stabilized conditions, the LAD and RDP were identified within a median of 29 seconds. In stabilized conditions, assessment was complete in 112 seconds (92 to 205) (median with range) for the LAD and 140 seconds (54 to 197) for the RDP. Stabilization of the OM3 was required for identification (16 [5 to 60]) and assessment (111 [82 to 225]). Overall identification was correct in 23 of 24 arteries. The OM branches and RDP became fully exposed endoscopically with stroke volume (SV) and mean arterial pressure (MAP) remaining at 67% +/- 11% (mean +/- standard error of the mean) and 70% +/- 5% of baseline values, respectively. Scanning itself did not augment the decrease in SV and MAP significantly. CONCLUSIONS: After proper endoscopic exposure and stabilization, robot-assisted epicardial ultrasound scanning enabled endoscopic identification and assessment of major coronary arteries within a median of 169 seconds per artery. Exposure, stabilization, and scanning were accompanied by an acceptable drop in stroke volume and mean arterial pressure.

Stapled coronary anastomosis with minimal intraluminal artifact: The S2 Anastomotic System in the off-pump porcine model.

OBJECTIVE: A reliable, easy-to-use, 1-shot anastomotic device will significantly push the barrier for less invasive coronary bypass surgery. The current study was designed to test the safety, efficacy, and early patency of a novel distal anastomotic device. METHODS: The S2 Anastomotic System (iiTech BV, Amsterdam, The Netherlands) was used in 10 consecutive pigs (73 kg) on a mild antiplatelet regimen. In each animal, the device was used to create an internal thoracic artery to left anterior descending bypass on the beating heart. The anastomoses were evaluated intraoperatively (n = 10), at 2 days (n = 2), and at 5 weeks (n = 8) by functional flow measurements, postmortem angiography, and histomorphologic examination. RESULTS: In all pigs, the S2 Anastomotic System rapidly created successful anastomoses at the first attempt (graft loading and coronary ischemia time: 1.2 +/- 0.3 minutes and 3.0 +/- 0.6 minutes) on target vessels of 1.6 to 2 mm inner diameter. There were no technical failures or anastomotic leaks requiring additional sutures. Both intraoperatively and at the time of death, ischemically induced peak hyperemic flow responses demonstrated widely patent bypasses, which were confirmed by postmortem angiography (FitzGibbon grade A, n = 10) and macroscopic evaluation (anastomotic orifice: 2 mm). Histomorphologic evaluation showed a normal healing response with negligible neointima covering the connector and limited streamlining repair tissue formation between the staple-like elements of the connector. CONCLUSIONS: The S2 Anastomotic System consistently created automated, fast, and reliable internal thoracic to coronary artery anastomoses on the porcine beating heart with excellent graft patency and healing characteristics at the 5-week follow-up.

Robot-assisted 13 MHz epicardial ultrasound for endoscopic quality assessment of coronary anastomoses.

In totally endoscopic coronary artery bypass surgery, intra-operative assessment of anastomotic quality is needed. We evaluated the endoscopic application of epicardial ultrasound to visualize the coronary anastomosis and detect a construction error. In 8 pigs (71-78kg), 16 internal mammary artery to left anterior descending coronary artery anastomoses were constructed conventionally, either correctly (n=8) or incorrectly with a suture cross-over construction error (n=8). A 13MHz mini-transducer (15x9x6mm) was introduced through a port and manipulated by the 'da Vinci' system. The chest was re-opened and scanning repeated manually. Postoperatively, macroscopic inspection served as reference and the intra-operative ultrasound images were scored as 'correct' or 'construction error' by two blinded observers. All anastomoses were scored accurately by both observers. One anastomosis constructed to be correct was scored as construction error, due to narrowing of the outflow corner and anastomotic orifice. Ultrasound images corresponded with macroscopic inspection. Closed-chest scan time was about 1.5 times longer than open-chest scan time, 176s (88-464) (median, range) versus 125s (75-314) (P=0.01), respectively. Closed-chest epicardial 13MHz ultrasound scanning required a median of 3min and enabled discrimination between correctly and incorrectly constructed coronary anastomoses.

Randomized comparison between stenting and off-pump bypass surgery in patients referred for angioplasty.

BACKGROUND: Stenting improves cardiac outcome in comparison with balloon angioplasty. Compared with conventional surgery, off-pump bypass surgery on the beating heart without cardiopulmonary bypass may reduce morbidity, hospital stay, and costs. The purpose, therefore, was to compare cardiac outcome, quality of life, and cost-effectiveness 1 year after stenting and after off-pump surgery. METHODS AND RESULTS: Patients referred for angioplasty (n=280) were randomly assigned to stenting (n=138) or off-pump bypass surgery. At 1 year, survival free from stroke, myocardial infarction, and repeat revascularization was 85.5% after stenting and 91.5% after off-pump surgery (relative risk, 0.93; 95% CI, 0.86 to 1.02). Freedom from angina was 78.3% after stenting and 87.0% after off-pump surgery (P=0.06). Quality-adjusted lifetime was 0.82 year after stenting and 0.79 year after off-pump surgery (P=0.09). Hospital stay after the initial procedure was 1.43 and 5.77 days, respectively (P<0.01). Stenting reduced overall costs by 2933 dollars (26.2%) per patient (8276 dollars versus 11 209 dollars; P<0.01). Stenting was more cost-effective in 95% of the bootstrap estimates. CONCLUSIONS: At 1 year, stenting was more cost-effective than off-pump surgery while maintaining comparable cardiac outcome and quality of life. Stenting rather than off-pump surgery, therefore, can be recommended as a first-choice revascularization strategy in selected patients.