Anastomotic devices for coronary artery bypass grafting: Technological options and potential pitfalls

A Novel Vascular Anastomotic Coupling Device for End-to-End Anastomosis of Arteries and Veins

OBJECTIVE

Hand-sutured (HS) techniques remain the gold standard for most microvascular anastomoses in microsurgery. HS techniques can result in endothelial lacerations and back wall suturing, leading to complications such as thrombosis and free tissue loss. A novel force-interference-fit vascular coupling device (FIF-VCD) system can potentially reduce the need for HS and improve end-to-end anastomosis. This study aims to describe the development and testing of a novel FIF-VCD system for 1.5 to 4.0 mm outside diameter arteries and veins.

METHODS

Benchtop anastomoses were performed using porcine cadaver arteries and veins. Decoupling force and anastomotic leakage were tested under simulated worst-case intravital physiological conditions. The 1.5 mm FIF-VCD system was used to perform cadaver rat abdominal aorta anastomoses.

RESULTS

Benchtop testing showed that the vessels coupled with the FIF-VCD system could withstand simulated worst-case intravital physiological conditions with a 95% confidence interval for the average decoupling force safety factor of 8.2 ± 1.0 (5.2 ± 1.0 N) and a 95% confidence interval for the average leakage rate safety factor of 26 ± 3.6 (8.4 ± 0.14 and 95 ± 1.4 μL/s at 150 and 360 mmHg, respectively) when compared to HS anastomotic leakage rates (310 ± 14 and 2,100 ± 72 μL/s at 150 and 360 mmHg, respectively). The FIF-VCD system was successful in performing cadaver rat abdominal aorta anastomoses.

CONCLUSION

The FIF-VCD system can potentially replace HS in microsurgery, allowing the safe and effective connection of arteries and veins. Further studies are needed to confirm the clinical viability and effectiveness of the FIF-VCD system.

Minimally Invasive Coronary Revascularisation Surgery: A Focused Review of the Available Literature

Minimally invasive coronary revascularisation was originally developed in the mid 1990s as minimally invasive direct coronary artery bypass (MIDCAB) grafting is a less invasive approach compared to conventional coronary artery bypass grafting (CABG) to address targets in the left anterior descending coronary artery (LAD). Since then, MIDCAB has evolved with the adoption of a robotic platform and the possibility to perform multivessel bypass procedures. Minimally invasive coronary revascularisation surgery also allows for a combination between the benefits of CABG and percutaneous coronary interventions for non-LAD lesions – a hybrid approach. Hybrid coronary revascularisation results in fewer blood transfusions, shorter hospital stay, decreased ventilation times and patients return to work sooner when compared to conventional CABG. This article reviews the available literature, describes standard approaches and considers topics, such as limited access procedures, indications and patient selection, diagnostics and imaging, techniques, anastomotic devices, hybrid coronary revascularisation and outcome analysis.

End-to-end vascular anastomosis using a novel magnetic compression device in rabbits: a preliminary study

Magnetic compression anastomosis (MCA) has been appreciated as an innovative alternative to manual suturing in vascular reconstruction. However, magnetic devices have limitations in their applications. The present study aimed to introduce a newly developed magnetic device for end-to-end vascular anastomosis. Twenty male New Zealand rabbits were randomly assigned to receive end-to-end postcaval vein anastomosis using either a newly designed MCA device (Group MCA) or continuous-interrupted suturing (Group CIS). The anastomotic patency was evaluated by Doppler or venography immediately, 1 week, and 12 weeks after surgery. Anastomotic quality was evaluated gross and microscopic histological study 12 weeks after surgery. The procedure was successfully performed and all animals survived until sacrifice. The duration of surgery and anastomosis time in Group MCA were significantly shorter compared to Group CIS (all p < 0.001), and the incidence of anastomotic patency and postoperative morbidity were comparable between the two groups (all p > 0.05). Hematoxylin-eosin staining showed that anastomotic intima from Group MCA was much smoother with more regularly arranged endothelial cells than from compared to the Group CIS. A novel MCA device was successfully applied in rabbit vascular anastomosis. We demonstrated the reliability and effectiveness of this newly developed MCA in this study.

Clinical outcomes of automated anastomotic devices: A metanalysis

Background and Aims

We investigated neurological events, graft patency, major adverse cardiovascular events (MACEs), and mortality at 1 year following coronary artery bypass grafting (CABG) surgery using automated proximal anastomotic devices (APADs) and compared the overall rates with the current literature.

Methods

A systematic review of all available reports of APADs use in the literature was conducted. Cumulative incidence and 95% confidence interval (CI) were the main statistical indexes. Nine observational studies encompassing a total of 718 patients were included at the end of the selection process.

Results

The cumulative event rate of neurological complications was 4.8% (lower‐upper limits: 2.8‐8.0, P < .001; I² = 72.907%, P = .002; Egger's test: intercept = –2.47, P = 0.16; Begg and Mazumdar test: τ = −0.20, p = 0.57). Graft patency was 90.5% (80.4 to 95.7, P < .001; I² = 76.823%, P = .005; Egger's test: intercept = –3.04, P = .10; Begg and Mazumdar test: τ = −0.67, P = .17). Furthermore, the overall incidence of MACEs was 3.7% (1.3‐10.4, P < .001; I² = 51.556%, P = .103; Egger's test: intercept = –1.98, P =  < .11; Begg and Mazumdar test: τ = −0.67, P = .17). Finally, mortality within 1 year was 5% (3.5‐7, P < .001; I² = 29.675%, P = .202; Egger's test: intercept = –0.91, P = .62; Begg and Mazumdar test: τ = −0.04, P = .88).

Conclusions

APADs do not seem to be correlated with a reduction of either neurological events or mortality. By contrast, these tools showed satisfactory one‐year graft patency and a low incidence of MACEs. Further research on this topic is warranted.

Multicenter Assessment of Grafts in Coronaries: Midterm Evaluation of the C-Port Device (the MAGIC Study)

OBJECTIVE

The commercially available C-Port distal anastomotic device (Food and Drug Administration cleared in 2007) is an automated miniature vascular stapler that performs the coronary anastomosis. This prospective multicenter registry sought to evaluate midterm patency using this device compared with hand-sewn grafts.

METHODS

Patients receiving at least one C-Port anastomosis during coronary artery bypass grafting surgery were enrolled at eight sites. Of the 117 patients enrolled, 78 patients (67%) with 104 C-Port vein grafts completed the study to patency assessment via computed tomography angiography. Clinical follow-up and index graft patency (Gated 64-slice computed tomography scan) were performed at least 12 months postoperatively. The primary efficacy endpoint was patency compared with the peer-reviewed results from the PRoject of Ex-vivo Vein graft ENgineering via Transfection IV (PREVENT IV) trial.

RESULTS

The patient population was consistent with the PREVENT IV placebo cohort. The mortality at 12 months was 0.85% (1/117). The major cardiac morbidity rate was 3.4% (4/117). The C-Port vein graft occlusion rate was 16.3% (17/104) compared with 26.6% (597/2242) in the PREVENT IV trial (P = 0.011). Within this study, C-Port graft occlusion rates were not significantly different from the hand-sewn grafts (P = 0.821).

CONCLUSIONS

The C-Port device is safe and effective in creating the distal anastomosis with equivalent patency rates to hand-sewn grafts at 12 months. When compared with hand-sewn anastomoses from a recent large prospective trial, the C-Port device demonstrated a statistically significant reduction in midterm graft occlusion. Further studies are required to evaluate its effect in less invasive coronary surgery.

Outcomes after aortic graft-to-graft anastomosis with an automated circular stapler: A novel approach

OBJECTIVE

Patients with complex aortic disease often require multistaged repairs with numerous anastomoses. Manual suturing can be time consuming. To reduce ischemic time, a circular stapling device has been used to facilitate prosthetic graft-to-graft anastomoses. Objectives are to describe this technique and assess outcomes.

METHODS

From February 2009 to May 2014, 44 patients underwent complex aortic repair with a circular end-to-end anastomosis (EEA) stapler at Cleveland Clinic. All patients had extensive aneurysms: 17 after ascending dissection repair, 10 chronic type B dissections, and 17 degenerative aneurysms. Stapler was used during total arch repair as an end-to-side anastomosis (n = 36; including first stage elephant trunk [ET] in 32, frozen ET in 3) and an end-to-end anastomosis during redo thoracoabdominal repair (n = 11). Three patients had the stapler used during both stages of repair. Patients underwent early and annual follow-ups with computed tomography analysis.

RESULTS

There were no bleeds, ruptures, or leaks at the stapled site, but 2 patients died. Complications included 7 reoperations not related to the site of stapled anastomosis and 6 tracheostomies, but there was no paralysis or renal failure. Mean circulatory arrest time was 16 ± 5 minutes. Mean follow-up was 26 ± 17 months and consisted of imaging before discharge, at 3 to 6 months, and at 1 year. Planned reinterventions included 21 second-stage ET completion: Endovascular (n = 18) and open (n = 3). There were 4 late deaths.

CONCLUSIONS

Use of an end-to-end anastomotic automated circular stapler is safe, effective, and durable in performing graft-to-graft anastomoses during complex thoracic aortic surgery. Further evaluation and refinement of this technique are warranted.

Minimally invasive direct coronary artery bypass grafting with an improved rib spreader and a new-shaped cardiac stabilizer: results of 200 consecutive cases in a single institution

Background

Performing minimally invasive direct coronary artery bypass (MIDCAB) grafting via small chest incisions on a beating heart is challenging. We report our experiences of MIDCAB with the utilization of both an improved rib spreader to harvest the left internal mammary artery (LIMA) and a new-shaped cardiac stabilizer to facilitate LIMA-left anterior descending (LAD) coronary anastomosis.

Methods

Between May 2012 and June 2104, a total of 200 patients who were consecutively operated on in this period were enrolled in this study. Data reported included demographic information, preoperative clinical and cardiac status, LIMA harvest time, postoperative in-hospital outcomes, and 30-day mortality.

Results

The average LIMA harvest time was 43 min. The mean age was 62.59 ± 10.19 years, and 45 of the 200 were females. The 30-day mortality was 0.5 % (one patient) due to perioperative myocardial infarction. Duration of mechanical ventilation and length of stay in intensive care unit was 9.27 ± 7.65 and 24.27 ± 17.85 h, respectively. The unit of packed RBC transfusion was 0.79 ± 1.58. Postoperative atrial fibrillation was observed in 14 (7 %) patients. There was no postoperative stroke, renal failure, or incision complication.

Conclusion

Performing MIDCAB with the improved retractor and stabilizer utilized in this study showed favorable outcomes in terms of harvesting the LIMA, postoperative morbidities, and 30-day mortality.

Optimization and Evaluation of a Vascular Coupling Device for End-to-End Anastomosis: A Finite-Element Analysis

Currently, end-to-end anastomosis of blood vessels is performed using suturing, which is time consuming, expensive, and subject to large degrees of human error. One promising alternative is a ring–pin coupling device. This device has been shown to be useful for venous anastomosis, but lacks the versatility necessary for arterial applications. The purpose of this study was to optimize a vascular coupling design that could be used for arteries and veins of various sizes. To achieve this, finite-element (FE) analysis was used to simulate the vessel–device interaction during anastomosis. Parametric simulations were performed to optimize the number of pins, the wing pivot point, and the pin offset of the design. The interaction of the coupler with various blood vessel sizes was also evaluated. Maximum strain in the vessel wall increased with the number of pins. The positions of the wings and pins were also important in dictating maximum strain, and improper dimensions lead to failure of the installation process. Extra force applied to the distal end of the vessel, or a supplementary tool, will be required during the coupler installation process to prevent vessels less than 3 mm inner diameter (0.5 mm wall thickness) from slipping off the coupler.

A New Vascular Coupler Design for End-to-End Anastomosis: Fabrication and Proof-of-Concept Evaluation

Traditional hand-suturing for vascular connection techniques is time consuming, expensive, and requires highly complex instruments and technical expertise. The aim of this study is to develop a new vascular coupler that can be used in end-to-end anastomosis surgery in an easier and more efficient way for both arteries and veins. The vascular coupler has four rotatable wings and one translatable spike in each wing. Prototypes were manufactured using polytetrafluoroethylene (PTFE) and high-density polyethylene (HDPE). A set of installation tools was designed to facilitate the anastomosis process. Proof-of-concept testing with the vascular coupler using plastic tubes and porcine cadaver vessels showed that the coupler should work as designed. A simplified finite element (FE) model assisted in the evaluation of the tearing likelihood of human vessels during installation of the coupler. Results of tests on the coupler showed that the vascular coupler could be efficiently attached to blood vessels, did not leak after the anastomosis was performed, had sufficient joint strength, and had little impact on flow in the vessel. The entire anastomosis process can be completed in 3 min when using the vascular coupler to join porcine cadaver vessels.

Design, fabrication, and testing of a novel end-to-end vascular coupling system

Microvascular anastomosis is common and necessary during reconstructive and free tissue transfer surgeries. Traditional hand suturing techniques are time consuming, subject to human error, and require complex instruments. Prior attempts including staples, ring-pin devices, cuffing devices, and clips were either more cumbersome, were unable to maintain a tight seal, or did not work for both arteries and veins. To provide a more efficient and reliable vessel anastomosis, a pin-free vascular coupling system that can be used for both arteries and veins was designed and manufactured. A set of corresponding instruments were developed to facilitate the anastomosis process. Both bench testing and ex vivo testing were performed to evaluate the operating abilities of the vascular coupling system. Preliminary studies were performed on cadaver pigs.

Coronary artery bypass grafting hemodynamics and anastomosis design: a biomedical engineering review

In this paper, coronary arterial bypass grafting hemodynamics and anastomosis designs are reviewed. The paper specifically addresses the biomechanical factors for enhancement of the patency of coronary artery bypass grafts (CABGs). Stenosis of distal anastomosis, caused by thrombosis and intimal hyperplasia (IH), is the major cause of failure of CABGs. Strong correlations have been established between the hemodynamics and vessel wall biomechanical factors and the initiation and development of IH and thrombus formation. Accordingly, several investigations have been conducted and numerous anastomotic geometries and devices have been designed to better regulate the blood flow fields and distribution of hemodynamic parameters and biomechanical factors at the distal anastomosis, in order to enhance the patency of CABGs. Enhancement of longevity and patency rate of CABGs can eliminate the need for re-operation and can significantly lower morbidity, and thereby reduces medical costs for patients suffering from coronary stenosis. This invited review focuses on various endeavors made thus far to design a patency-enhancing optimized anastomotic configuration for the distal junction of CABGs.

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.

The primary and secondary prevention of coronary artery disease: American College of Chest Physicians Evidence-Based Clinical Practice Guidelines (8th Edition)

The following chapter devoted to antithrombotic therapy for chronic coronary artery disease (CAD) is part of the Antithrombotic and Thrombolytic Therapy: American College of Chest Physicians Evidence-Based Clinical Practice Guidelines (8th Edition). Grade 1 recommendations are strong and indicate that the benefits do or do not outweigh risks, burden, and costs. Grade 2 suggests that individual patient values may lead to different choices (for a full understanding of the grading see the "Grades of Recommendation" chapter by Guyatt et al in this supplement, CHEST 2008; 133[suppl]:123S-131S). Among the key recommendations in this chapter are the following: for patients with non-ST-segment elevation (NSTE)-acute coronary syndrome (ACS) we recommend daily oral aspirin (75-100 mg) [Grade 1A]. For patients with an aspirin allergy, we recommend clopidogrel, 75 mg/d (Grade 1A). For patients who have received clopidogrel and are scheduled for coronary bypass surgery, we suggest discontinuing clopidogrel for 5 days prior to the scheduled surgery (Grade 2A). For patients after myocardial infarction, after ACS, and those with stable CAD and patients after percutaneous coronary intervention (PCI), we recommend daily aspirin (75-100 mg) as indefinite therapy (Grade 1A). We recommend clopidogrel in combination with aspirin for patients experiencing ST-segment elevation (STE) and NSTE-ACS (Grade 1A). For patients with contraindications to aspirin, we recommend clopidogrel as monotherapy (Grade 1A). For long-term treatment after PCI in patients who receive antithrombotic agents such as clopidogrel or warfarin, we recommend aspirin (75 to 100 mg/d) [Grade 1B]. For patients who undergo bare metal stent placement, we recommend the combination of aspirin and clopidogrel for at least 4 weeks (Grade 1A). We recommend that patients receiving drug-eluting stents (DES) receive aspirin (325 mg/d for 3 months followed by 75-100 mg/d) and clopidogrel 75 mg/d for a minimum of 12 months (Grade 2B). For primary prevention in patients with moderate risk for a coronary event, we recommend aspirin, 75-100 mg/d, over either no antithrombotic therapy or vitamin K antagonist (Grade 1A).