Is the GraftConnector a valid alternative to running suture in end-to-side coronary arteries anastomoses?

A different technique for sutureless coronary bypass grafting

Introduction

Many coronary anastomotic devices have been designed to replace manual stitching in coronary surgery; however, interestingly, none of them became widespread. Our aim was to work out an easy and fast endoluminal vessel-to-vessel stent bridge distal anastomotic technique.

Materials and methods

Ten coronary arteries of eight fresh human hearts were used in this study. The anastomosis was performed with the implantation of a graft vessel into the lumen of the coronary artery by performing stent fixation. The technique is described and photo documented in detail. The durability and the conductibility of the anastomosis were examined with intraluminal endoscopy, functional streaming test, and a coloring of the vessels.

Results

The anastomosis had great results in all cases. Obstruction, dissection, or dislocation of the vessels was not observable.

Conclusions

This study confirmed the ex-vivo feasibility of the described technique. This method can be an easy, fast, and reliable method applied in the endoscopic distal coronary artery anastomosis surgery. The development of stents adapted to this method and the in-vivo testing of this technique are necessary for the future.

A systematic review of the safety and efficacy of distal coronary artery anastomotic devices

Interest in minimally invasive and off-pump cardiac surgical techniques has promoted the development of automated distal anastomotic devices (DADs) to facilitate construction of coronary artery anastomosis. Several DADs have been proposed for potential use in coronary surgery. However, a number of technical failures and uncertainty around both short-term morbidity and long-term patency have limited the generalized uptake of these devices. A systematic literature search identified 28 studies, incorporating 970 patients who underwent coronary artery bypass grafting using a DAD. Eight different devices were identified including Heartflo, St Jude, U-clip, vessel closure system, C-port, magnetic vascular positioner and coronary anastomosis coupler. Thirty-day mortality, cardiac-specific mortality and myocardial infarction were equal between DADs and hand-sewn cases (1.3, 0.3 and 0.8%, respectively). The overall proportion of postoperative haemorrhage was higher in the anastomotic device group (2.3%) than in the group with hand-sewn anastomoses (1.5%) although not statistically significant. Overall graft patency was 97.2% at <1 month, 94.6% at 1-3 months and 92.3% at >3 months. Of the currently available systems, the U-clip device was found to provide the best overall postoperative outcomes, which included a patency of 96.1% at >3months. The current literature is limited by its predominantly observational study design and lack of directly comparative studies. Furthermore, inter-study variation in patient selection, anticoagulation strategies and follow-up periods prevents quantitative comparison. Future research necessitates multicentre randomized, controlled studies to provide a direct comparison of current and future anastomotic device systems with established hand-sewn techniques in both the short and long term.

The vascular connector, design of a new device for sutureless vascular anastomosis

BACKGROUND

In recent years, several methods and new techniques have been studied and proposed for establishment of sutureless vascular anastomoses, streaming use of sutureless vascular surgery in the future.

PRESENTATION OF THE HYPOTHESIS

The new vascular connector (NVC) is a hypothetical design of a vascular device, proposed for creation and maintenance of sutureless vascular anastomosis. Implication of NVC would introduce a new device and technique in establishment of sutureless vascular anastomosis in which surgical approach is minimized and so post-operation disorders. It would eliminate need for suture; shorten clampage and operation time, consequently reducing stress for both, the surgeon and the patient. It enables the creation of vascular anastomosis fast, simple, safe, reliable, with satisfactory patency and stability of anastomosis.

TESTING THE HYPOTHESIS

Efficacy of NVC needs to be evaluated in further studies, in order to be confirmed for clinical use. The effectiveness of NVC should be verified firstly in vitro and in vivo tests; and by animal experiments. The likelihood of its negative influence in thrombogenicity should be well evaluated.

IMPLICATIONS OF THE HYPOTHESIS

Implication of the new vascular connector (NVC) would be of interest to both patients and the surgeon due to the following main achievements: 1) enables the creation of vascular anastomosis fast and simple, 2) significant shortening of clampage time of blood vessels and operation time-this assumption would be followed by reduced risk of operative and post-operative complications and length of hospital stay or admission to Intensive care unit, 3) safe and reliable, 4) compatible with any blood vessel and standard vascular graft, 5) using the NVC we will reduce in minimum need for replaced blood volume, 6) reduces the cost of treatment. It is anticipated that the NVC would provide shorter operation time and least operative and post-operative complications in creation of sutureless vascular anastomosis.

Hemodynamic Performance of a Sutureless Anastomosis Device (the Graft Connector): A Numerical Study

Sutureless anastomosis devices have been developed to facilitate arterial bypass surgery on the beating heart. However, these devices can significantly alter the hemodynamics at the end-to-side anastomosis and in the host artery, leading to the formation of thrombus or/and intimal hyperplasia (IH). In this study, a numerical analysis was performed on the hemodynamic performance of the Graft Connector (GC), a sutureless anastomosis device, under pulsatile flow conditions. The results showed that blood flow was severely disturbed in the GC model with the formation of vortices and flow stagnation at the bed and the toe, and distal to each of the stent struts, which led to low wall shear stresses and high oscillating shear indices in these regions. This may cause severe IH in the host artery and compromise the performance of the device. Based on the numerical study, suggestions were proposed for the design of the GC to improve its performance.

Magnetic Vascular Port in minimally invasive direct coronary artery bypass grafting

BACKGROUND

Minimally invasive direct coronary artery bypass grafting (MIDCAB) is a well-established operative procedure. However, it is technically demanding and is therefore somewhat underused. We evaluated the clinical and angiographic outcome of patients undergoing a MIDCAB procedure with the Ventrica Magnetic Vascular Port (MVP) system.

METHODS AND RESULTS

A Ventrica MVP system was used in 10 of 11 selected MIDCAB patients. The system consists of 6 magnetic clips, with 3 clips forming a set. One magnetic clip set is positioned at the arteriotomy of the target artery and of the bypass graft using a preloaded delivery system. These ports then form an anastomosis by magnetic coupling. The mean age of the 10 patients (6 male) was 60.3+/-11.0 years. Three patients had an angiogram at the time of discharge and 8 returned for a 6-month angiogram. The total procedure time was 128.2+/-12.2 minutes. The mean anastomotic time was 199 seconds. The mean ischemic time during the anastomosis was 146+/-146 seconds. There were no in-hospital complications and no device-related adverse events. All 3 predischarge and all 8 6-month angiograms showed patent anastomoses.

CONCLUSIONS

The magnetic vascular port facilitates the MIDCAB procedure significantly and reduces the ischemic time during the anastomosis. This minimally invasive procedure has the potential to be an alternative to percutaneous transluminal coronary angioplasty and stenting in proximal left anterior descending (LAD) stenosis. It may expand the acceptance of hybrid procedures in which a left internal mammary artery (LIMA)-to-LAD graft optimally supplies the anterior wall and the septum while the circumflex and right coronary artery may be treated interventionally.

Clinical and angiographic results after mechanical connection for distal anastomosis in coronary surgery

BACKGROUND

Sutureless anastomotic devices are of increasing interest in cardiovascular surgery. We investigated the stainless steel clip system of St Jude Medical/Anastomotic Technology Group (Maple Grove, Minn) to connect saphenous vein grafts with coronary arteries.

METHODS

Forty-five patients were enrolled in this feasibility study performed on patients who had on-pump coronary artery bypass grafting, but 32 patients only received 1 distal anastomosis with this investigational device (2.5 mm [n = 14] and 2.0 mm [n = 18]). Thirteen were excluded because target vessels were too small, calcified, or tortuous. The system consists of an expandable clip mounted on a balloon catheter; delivery is obtained during balloon inflation. The main differences between the 2.5-mm and 2.0-mm devices are different loading and deployment in smaller coronary arteries for the 2.0-mm device.

RESULTS

A connecting device was deployed on the right coronary artery in 14 patients, the posterior descending branch in 12 patients, the obtuse marginal in 5 patients, and the posterolateral branch in 1 patient. Perfect hemostasis of the sutureless connector anastomosis was obtained in 28 patients. Three connectors were removed because of minor leakage at the connection site, and 1 connector was removed because of mismanipulation after successful deployment. Hand-sewn anastomosis was performed at the same arteriotomy site. Intraoperative flow was assessed by the transit time method and averaged 71 +/- 24 mL/min. One patient died of neurologic injury; the connector was patent at autopsy. One patient had a perioperative myocardial infarction. There was no adverse cardiac event in the remaining patients. All patients underwent clinical follow-up after 6 and 12 months and 35 angiograms were available in 21 patients: after 3 and 6 months, 17 anastomoses were patent and the saphenous vein graft was occluded in 4 patients.

CONCLUSIONS

The coronary connector system from St Jude Medical/Anastomotic Technology Group allows consistently uniform sutureless connection between the saphenous vein graft and coronary artery. Loading and deployment require careful training. This technology is under constant development and may give a significant boost to less invasive coronary revascularization techniques.

Sutureless Videoendoscopic Thoracic Aorta to Iliac Artery Bypass: The Easiest Approach to Occlusive Aorto-iliac Diseases

OBJECTIVE

We designed an animal study to determine the feasibility of videoendoscopic thoracic aorta to iliac artery bypass using a sutureless anastomotic device for proximal anastomosis construction.

METHODS

In 12 pigs the descending thoracic aorta was exposed using the thoracoscopic technique. A 4 mm PTFE thin wall graft was used as conduit. The proximal anastomosis was constructed using a mechanical device for sutureless anastomosis inserted through the camera port incision. The prosthesis was passed through the diaphragm in the retroperitoneal space and the distal anastomosis was done with running suture.

RESULTS

The operation was successfully completed in 11 animals. One animal died due to hemorrage during anastomosis construction. Mean graft flow was 144 ml/min (range 88-167 mmHg). The angiogram showed no graft kinking or stenosis. Total operative time was 58 min (range 47-68 min).

CONCLUSIONS

This approach allows quick and excellent exposure of the entire descending thoracic aorta. The use of the sutureless device to perform the proximal anastomosis dramatically reduces the technical demands of this procedure and could avoid an aortic clamp.

Clinical experience with devices for facilitated anastomoses in coronary artery bypass surgery

Recent developments in minimally invasive coronary artery surgery have been driven by the introduction of new technologies which should facilitate precise surgical maneuvers on the beating heart within confined spaces. Such technologies include coronary stabilizer systems, cardiac positioning vacuum-assisted devices, and telemanipulative systems. Despite these developments, standard suturing techniques using running polypropylene material remains a limiting factor in the surgeon's ability to perform complete revascularization with high quality anastomoses through minimal approaches to the chest cavity. Clinical validation of proximal and distal anastomotic devices has the potential to substantially improve and perhaps revolutionize minimally invasive coronary surgery. Ideal characteristics of such devices would include applicability to all conduit types, all coronary sizes, interchangeable proximal/distal sequencing of the anastomosis, and safe bail out for device malfunction. However there is an urgent need to define the performance objectives of such systems as well as the general criteria for proper and comparable evaluation and validation of different systems in animal models and subsequently in controlled prospective clinical studies. This review summarizes the most interesting systems available in both experimental and clinical settings.

Mechanical properties of porcine and human arteries: implications for coronary anastomotic connectors

BACKGROUND

To determine whether the pig is an appropriate experimental animal for studies on distal anastomotic connectors in coronary artery bypass surgery, the mechanical properties of young porcine and old human coronary and internal mammary arteries were compared within and beyond the physiologic range of strains.

METHODS

Coronary arteries from 6 humans and 8 pigs were studied as well as internal mammary arteries of 3 humans and 6 pigs (human, aged 61 to 85 years; pig, 78.7 +/- 5.8 kg [mean +/- SD]). Pressure-diameter, pressure-axial force, circumferential and axial stress-strain relations, and dimensions were measured.

RESULTS

The dimensions of the porcine and human coronary and internal mammary artery were generally similar but wall thickness was smaller in the porcine internal mammary artery (0.35 +/- 0.07 mm versus 0.71 +/- 0.06 mm, respectively, p = 0.002). The porcine internal mammary artery wall was less elastic than the coronary artery wall, whereas in humans both arteries displayed similar elasticity. Overall the porcine arteries were far more elastic in both circumferential and axial direction compared with the human arteries. Consequently the porcine arteries could be safely stretched by 60% to 70% compared with about 20% for the human arteries before reaching their maximum circumferential strain.

CONCLUSIONS

The three times greater elasticity of porcine compared with human coronary and internal mammary artery walls may result in underestimation of wall stress and the risk of wall injury when coronary connectors that involve overstretching of the wall are evaluated in the pig.

Coronary anastomotic devices: blood-exposed non-intimal surface and coronary wall stress

OBJECTIVE

This study compares the area of blood-exposed non-intimal surface in device-constructed anastomoses with the conventionally sutured anastomosis and examines the technical feasibility of 0 blood-exposed non-intimal surface anastomosis configurations.

METHODS

In the device-constructed anastomosis, blood-exposed non-intimal surface was estimated in all anastomosis configurations identified in truly new (ie, nonduplicate and nonrelated) patent applications and in anastomotic devices recently introduced by several institutions. In the sutured anastomosis, blood-exposed non-intimal surface area was estimated by analysis of previously investigated anastomoses. In 0 blood-exposed non-intimal surface anastomosis configurations, finite element modeling was used to calculate coronary wall stress.

RESULTS

By the end of 2001, 57 truly new applications for the distal coronary anastomosis had been published, categorized in 11 types of anastomosis configurations. The tissue blood-exposed non-intimal surface area (ie, non-intimal tissue surface area) ranged from 0 to 6 mm(2). Approximate total blood-exposed non-intimal surface areas (ie, sum of tissue blood-exposed non-intimal surface and foreign body surface area) in recent devices are 80 mm(2) (GraftConnector, Jomed, Helsingborg, Sweden); 33 mm(2) (Magnetic Vascular Positioner rings, Ventrica, Inc, Fremont, Calif); 4.3 mm(2) (distal connector of St Jude Medical, Inc, St Paul, Minn); and 0.3 mm(2) (Crinoline frame, University Medical Center Utrecht/Delft University of Technology, The Netherlands). The sutured anastomoses, in contrast, contained approximately 1.3 mm(2) blood-exposed non-intimal surface area. The mean peak porcine coronary wall stress in 0 blood-exposed non-intimal surface anastomosis configurations with greater than 90 degrees arteriotomy edge eversion ranges from 0.4 to 0.8 N/mm(2) compared with the mean porcine coronary tear stress of 0.8 N/mm(2).

CONCLUSIONS

In recently introduced devices for clinical use, the total blood-exposed non-intimal surface area ranges from 4.3 to 80 mm(2) compared with 1.3 mm(2) in sutured anastomoses. The blood-exposed non-intimal surface area depends on anastomotic orifice size, wall thickness, and bonding components' location and size. Deforming the coronary wall to most of the 0 blood-exposed non-intimal surface anastomosis configurations leads to dangerously high stress concentrations in the coronary arteriotomy corners.

Flow resistance over technical anastomoses in relation to the angle of distal end-to-side connections

OBJECTIVE

The fluid dynamics within the anastomotic region may contribute to graft failure. The aim was to investigate how flow resistance is affected by anastomotic angle and viscosity.

DESIGN

Technical end-to-side anastomoses of 3-mm inlet/outlet diameter were precision-drilled in plastic blocks at 90 degrees, 60 degrees, 45 degrees, and 30 degrees angles, with 0 degrees as control to calculate relative resistance. Five pressure loads of 200-1000 mmH (2) O and two fluid viscosities were tested using pulsatile perfusion.

RESULTS

Absolute resistances showed a significant linear correlation with pressure, regardless of anastomotic angle and with similar slope values. Increased viscosity produced an upward shift in resistance but otherwise had no effect. However, the relative resistances showed transition zones at increased pressures, which were sensitive to viscosity. The 30 degrees angle produced less resistance than steeper angles.

CONCLUSION

Previous studies gave contradictory results about the importance of anastomotic angle. Our findings suggest that in iso-diametrical technical anastomoses a low angle is favorable. The complexity of angularity in distal aorto-coronary anastomoses was illustrated by threshold phenomena at different pressures, possibly due to induced turbulence and anastomotic resonance.

Future technology for off-pump coronary artery bypass (OPCAB)

Over the past 5 years, many coronary artery surgeons have embraced technology and advanced the field of beating heart surgery to the point where off-pump coronary artery bypass (OPCAB) is becoming a mature procedure. Enabling technologies are now available for all stages of the procedure, including cardiac positioning, coronary artery stabilization, coronary artery visualization, and performance of the proximal and distal anastomoses. Despite these successes, only a minority of cardiac surgeons performs this procedure routinely. Proponents of OPCAB and the medical device industry will need to continue to develop new technologies to make OPCAB less technically challenging and more widely accepted. Progress towards routine single-vessel off-pump totally endoscopic coronary artery bypass has been slow. Translating the benefits of multivessel OPCAB to an endoscopic setting remains a formidable challenge that will require further technologic breakthroughs.