Evaluating the Arteriotomy Size of a New Sutureless Coronary Anastomosis Using a Finite Volume Approach.

OBJECTIVES: The ELANA® Heart Bypass creates a standardized sutureless anastomosis. Hereby, we investigate the influence of arteriotomy and graft size on coronary hemodynamics. METHODS: A computational fluid dynamics (CFD) model was developed. Arteriotomy size (standard 1.43 mm2; varied 0.94 - 3.6 mm2) and graft diameter (standard 2.5 mm; varied 1.5 - 5.0 mm) were independent parameters. Outcome parameters were coronary pressure and flow, and fractional flow reserve (FFR). RESULTS: The current size ELANA (arteriotomy 1.43 mm2) presented an estimated FFR 0.65 (39 mL/min). Enlarging arteriotomy increased FFR, coronary pressure, and flow. All reached a maximum once the arteriotomy (2.80 mm2) surpassed the coronary cross-sectional area (2.69 mm2, i.e. 1.85 mm diameter), presenting an estimated FFR 0.75 (46 mL/min). Increasing graft diameter was positively related to FFR, coronary pressure, and flow. CONCLUSION: The ratio between the required minimal coronary diameter for application and the ELANA arteriotomy size effectuates a pressure drop that could be clinically relevant. Additional research and eventual lengthening of the anastomosis is advised.

Preclinical Comparison of Distal Off-Pump Anastomotic Remodeling: Hand-Sewn Versus ELANA Heart Bypass.

Objective: The ELANA Heart Bypass System is a new sutureless technique for coronary anastomoses. A titanium clip connects the graft with the coronary artery, whereafter the arteriotomy is performed by excimer laser. Since this anastomotic construction evidently differs from the standard hand-sewn anastomosis, we aim to evaluate the process of anastomotic healing and remodeling. Methods: Preclinical evaluation of anastomotic remodeling in 42 pigs who underwent off-pump left internal mammary artery to left anterior descending artery anastomosis by either the ELANA Heart Bypass (n = 24) or the hand-sewn (n = 18) technique. Anastomotic remodeling was evaluated by scanning electron microscopy and histology in short-term follow-up intervals up to 3 months. Anastomotic patency is determined by coronary angiography at latest follow-up before termination. Results: The nonendothelial surface of both the ELANA and the hand-sewn anastomoses were covered with neointima from 14 days onwards. Only half the amount of intima hyperplasia was present in the anastomotic surface of the patent ELANA anastomosis, compared with the hand-sewn anastomosis (98 [48-1358] vs 218 [108-296] µm, P = 0.001). Yet patency of the ELANA was inferior to the hand-sewn anastomoses (79% vs 100%, P = 0.06). Conclusions: This study shows the technical perioperative feasibility of the ELANA Heart Bypass System. Although limited intima hyperplasia was observed, hand-sewn anastomoses had superior patency during follow-up. The results of this trial suggest that an additional study with a new prototype is required before clinical implementation.

Preclinical Feasibility and Patency Analyses of a New Distal Coronary Connector: The ELANA Heart Bypass.

OBJECTIVE: This preclinical study determines the feasibility and 6-month patency rates of a new distal coronary connector, the Excimer Laser Assisted Nonocclusive Anastomosis (ELANA) Heart Bypass. METHODS: Twenty Dutch Landrace pigs received either a hand-sewn (n = 8) or an ELANA (n = 12) left internal thoracic artery to left anterior descending artery anastomosis, using off-pump coronary artery bypass grafting. Six-month patency rates were demonstrated by coronary angiography and histological evaluation. Throughout, procedural details and complication rates were collected. RESULTS: The ELANA Heart Bypass demonstrated 0% mortality and complication rates during follow-up. It was demonstrated feasible, with comparable perioperative flow measurements (ELANA vs hand-sewn, median [min to max], 24 [14 to 28] vs 17 [12 to 31] mL/min; P = 0.601) and fast construction times (3 [3 to 7] vs 31 [26 to 37] min; P < 0.001). Yet, an extra hemostatic stitch was needed in 25% of the ELANA versus 12.5% of the hand-sewn anastomoses. The 6-month patency rate of the ELANA Heart Bypass was 83.3% versus 100% in hand-sewn anastomoses. The 2 occluded ELANA-anastomoses were defined model-based errors. CONCLUSIONS: The ELANA Heart Bypass facilitates a sutureless distal coronary anastomosis. A design change is suggested to improve hemostasis and will be evaluated in future translational studies. This new technique is a potential alternative to hand-sewn anastomoses in (minimally invasive) coronary surgery.

A Laser-Assisted Anastomotic Technique: Feasibility on Human Diseased Coronary Arteries.

OBJECTIVE: Atherosclerotic disease might hamper the efficacy of the Excimer laser-assisted Trinity Clip anastomotic connector in coronary arteries. Therefore, its efficacy was evaluated on human diseased coronary arteries (study 1). In addition, the acute laser effects onto the coronary wall were assessed (study 2). METHODS: Thirty-eight anastomoses were constructed on ex vivo human hearts. Atherosclerosis was histopathologically determined and subsequently related to the success of the technique (ie, connector positioning and laser punching; study 1). In addition, 20 anastomoses were constructed in an ex vivo (porcine, n = 8) and an in vivo [rabbit (n = 9) and porcine (n = 3)] model. Subsequently, the coronary was histologically studied on the presence of laser-induced damage (study 2). RESULTS: In 13 of 38 anastomoses (study 1), the connector was malpositioned, 3 because of a severely diseased coronary wall and 10 because of an inner diameter less than the intended target range. The laser-punch success rates on coronary arteries with an early and advanced lesion were 100% (16/16) and 89% (8/9; lesions were located in the inferolateral wall), respectively. In one case, an advanced lesion (ie, fibrocalcified plaque) was located in the superolateral wall and caused a laser-punch failure. No histological signs of laser-induced damage were observed, in case of correct use (study 2). CONCLUSIONS: This study demonstrates the feasibility of an anastomotic connector on human diseased coronary arteries and shows that lasering does not induce coronary wall damage. However, careful selection of the coronary, regarding the target inner diameter and disease status, will prevent construction failures. This connector could facilitate less invasive coronary artery bypass grafting.

Total Arterial Minimally Invasive Direct Coronary Artery Bypass Surgery Facilitated by the Trinity Clip Connector.

OBJECTIVE: This pilot study evaluated the feasibility of total arterial minimally invasive direct coronary artery bypass surgery by using the Trinity Clip anastomotic connector in an acute porcine model. METHODS: In 3 pigs, the left and right internal thoracic arteries (LITA and RITA) were harvested conventionally and the chest closed subsequently. After a left lateral thoracotomy, the coronary target was positioned and stabilized by an endo-starfish and octopus. A free RITA-to-LITA y-graft, with a LITA-to-left anterior descending coronary artery (LAD) and a free RITA-to-obtuse marginal or posterolateral or posterior descending artery, was constructed using the Trinity Clip. Patency was assessed with angiography (n = 3 anastomoses). RESULTS: The anastomotic procedure was feasible via a small lateral thoracotomy, with a fast construction of the y-graft, and successful application of the mounted complex (ie, graft, connector, and laser, temporarily fixated by a fixation clip) onto the LAD. Access to the obtuse marginal artery, posterolateral artery, and posterior descending artery was possible, with successful construction, resulting in patent anastomoses. CONCLUSIONS: This experimental pilot study demonstrates the feasibility of the anastomotic technique in a total arterial minimally invasive direct coronary artery bypass approach. Revascularization of the anterior, lateral, and inferoposterior regions of the heart is possible. However, visibility during the introduction of the connector was limited, and videoscopic assistance is essential to allow for successful construction. The anastomotic technique has potential to facilitate minimally invasive coronary bypass surgery.

Evaluation of a novel laser-assisted coronary anastomotic connector - the Trinity Clip - in a porcine off-pump bypass model.

To simplify and facilitate beating heart (i.e., off-pump), minimally invasive coronary artery bypass surgery, a new coronary anastomotic connector, the Trinity Clip, is developed based on the excimer laser-assisted nonocclusive anastomosis technique. The Trinity Clip connector enables simplified, sutureless, and nonocclusive connection of the graft to the coronary artery, and an excimer laser catheter laser-punches the opening of the anastomosis. Consequently, owing to the complete nonocclusive anastomosis construction, coronary conditioning (i.e., occluding or shunting) is not necessary, in contrast to the conventional anastomotic technique, hence simplifying the off-pump bypass procedure. Prior to clinical application in coronary artery bypass grafting, the safety and quality of this novel connector will be evaluated in a long-term experimental porcine off-pump coronary artery bypass (OPCAB) study. In this paper, we describe how to evaluate the coronary anastomosis in the porcine OPCAB model using various techniques to assess its quality. Representative results are summarized and visually demonstrated.

Six-month healing of the nonocclusive coronary anastomotic connector in an off-pump porcine bypass model.

OBJECTIVE: This pilot study evaluates the anastomotic healing of the Excimer Laser Assisted Nonocclusive Anastomosis coronary connector at 6 months in a porcine off-pump coronary artery bypass (OPCAB) model. METHODS: Left internal thoracic artery to left anterior descending coronary artery bypass in two animals and left internal thoracic artery to left anterior descending coronary artery and right internal thoracic artery to right coronary artery bypasses in one animal were evaluated intraoperatively and at 6 months. The anastomoses (n = 4) were examined by angiography, intravascular ultrasound, optical coherence tomography, scanning electron microscopy, and histology. RESULTS: At follow-up, all anastomoses (n = 4) were fully patent (FitzGibbon grade A). Scanning electron microscopy demonstrated complete endothelial coverage of the anastomotic surface, and histology showed minimal streamlining intimal hyperplasia. The in vivo intravascular ultrasound and optical coherence tomography acquisitions confirmed histologic findings. Optical coherence tomography demonstrated 0.06-mm intimal coverage of the intraluminal part of the connector along the full circumference of the anastomosis. CONCLUSIONS: In this pilot study, the Excimer Laser Assisted Nonocclusive Anastomosis coronary connector showed an excellent healing response on the long-term in the porcine OPCAB model. Hence, this new concept might be a potential alternative to hand-sutured anastomosis in (minimally invasive) OPCAB surgery.

The nonocclusive laser-assisted coronary anastomotic connector in an off-pump porcine bypass model.

OBJECTIVES: To facilitate minimally invasive coronary artery bypass grafting, a simplified alternative for hand-sutured anastomoses must be developed. We assessed the feasibility and anastomotic healing of the ameliorated Excimer laser-assisted nonocclusive anastomosis coronary prototype connector in an acute rabbit study (study 1) and in a long-term porcine off-pump coronary bypass study (study 2). METHODS: Eighteen anastomoses were constructed on the abdominal aorta of the rabbit. In the porcine model, 15 left internal thoracic artery to left anterior descending coronary artery bypasses were evaluated intraoperatively and at 4 hours, 4 and 10 days, 2, 3, and 5 weeks, and 6 months (each n = 2 anastomoses). The anastomoses were examined by angiography, flow measurements, fractional flow reserve, coronary flow reserve, histologic features, and scanning electron microscopy. RESULTS: In study 1, all 18 anastomoses were patent and resisted supraphysiologic pressures (n = 12, 300 mm Hg). In study 2, the connector enabled nonocclusive and fast (7.7 ± 2.2 minutes, mean ± standard deviation) anastomosis construction. All but 1 of 15 anastomoses (owing to a technical error) were fully patent (FitzGibbon grade A) at follow-up. Histologic examination and scanning electron microscopy demonstrated complete endothelialization of the anastomoses at 10 days. At 6 months, no flow-limiting but streamline-covering intimal hyperplasia was shown (fractional flow reserve, 0.93 ± 0.07 mean ± standard deviation). CONCLUSIONS: The new nonocclusive coronary connector is easy to use, and the long-term results suggest favorable healing and remodeling in the porcine model. After downsizing, this anastomotic device, with its emphasis on zero ischemia and simplified prebounding of vessel walls, has intrinsic potential for minimally invasive off-pump coronary artery bypass surgery.

A new nonocclusive laser-assisted coronary anastomotic connector in a rabbit model.

OBJECTIVE: The Excimer laser-assisted nonocclusive anastomotic technique is a nonocclusive, facilitated bypass technique that is currently Conformité Européenne and Food and Drug Administration approved for clinical application in neurosurgery. In the present study, we assessed the safety and feasibility of a newly developed Excimer laser-assisted nonocclusive anastomosis-based prototype coronary anastomotic connector in an acute rabbit abdominal aortic bypass model before application in experimental coronary bypass surgery. In addition, 2 sealants were tested to facilitate anastomotic hemostasis in the current device prototype. METHODS: A total of 40 anastomoses were constructed on the abdominal aorta (3.5 mm outer diameter) of 10 rabbits. The anastomotic circumference was sealed by a surgical sealant to obtain complete hemostasis (BioGlue vs TachoSil). The anastomoses were evaluated by flow measurements construction time, hemostasis, histologic analysis, and burst pressure testing. RESULTS: The connector enabled a nonocclusive and fast (6.0 ± 1.7 minutes, mean ± SD [including sealing]) anastomosis construction and complete hemostasis in 95% (35/37). Sealing with BioGlue was faster than with TachoSil (19% vs 53% of construction time). Despite technical imperfections (7/40 failures to completely retrieve the flap by the laser), all 40 anastomoses were patent, showed reproducible construction with intima-adventitia apposition, streamlining thrombus coverage of the intraluminal laser rim, and no vessel wall damage. All anastomoses resisted ex vivo supraphysiologic pressures (> 300 mm Hg). CONCLUSIONS: The results of the present study have demonstrated that the Excimer laser-assisted nonocclusive anastomotic connector is safe and reliable and can be efficiently applied in an acute rabbit abdominal aortic bypass model. Provided the limitations can be addressed, this easy-to-use and nonocclusive technique has the potential to facilitate minimally invasive coronary bypass surgery.