Compliance of Textile Vascular Prostheses Is a Fleeting Reality.

OBJECTIVE: Compliance is considered to be a major property influencing the long term performances of synthetic vascular substitutes that could play a role in anastomotic false aneurysm and intimal hyperplasia stenosis onset. Over the last decades, manufacturers have tried to develop substitutes that mechanically mimic arterial properties and avoid a compliance mismatch at the anastomoses in particular. However, data are missing about how initial compliance properties could change with time. The goal of this study was to evaluate how the compliance of vascular grafts evolves under cyclic loading conditions in vitro. METHODS: The compliance of three different models of commercially available textile polyethylene terephthalate (PET) grafts was evaluated. Tests were performed with and without their original coating. Compliance was assessed with a specific device dedicated to measure the deformations undergone by a graft under cyclic pressure loading conditions, using image analysis software. In each experiment, image analysis was performed under 60 and 140 mmHg pressure loading conditions at loading start (H0) and after three, six, and 24 h (H3, H6, H24) loading time. Average radial, longitudinal, and volumetric compliance was calculated from the obtained images. RESULTS: Twenty-four samples were tested. Results demonstrate that all values decreased significantly within only a few hours. On average, the loss of compliance after 3 h of cyclic loading ranged on average from 35% for longitudinal compliance to 39% for radial compliance and 37% (p < .050) for volume compliance. After 24 h, the loss of radial, longitudinal and volume compliance was respectively 63 ± 3%, 60.5 ± 2% and 61 ± 7%. CONCLUSION: In this in vitro model, PET graft compliance has already decreased significantly within 3 h. The rapid loss of compliance identified in this experimental study helps explain the mismatch mentioned in clinical observations.

Learning Curve of Robotic-Assisted Anastomosis: Shorter than the Laparoscopic Technique? An Educational Study.

BACKGROUND: Achieving aortic anastomosis in laparoscopic surgery remains a technical challenge. The Da Vinci robot could theoretically counteract this issue by minimizing the technical challenge. The aim of this study was to compare the learning curves of performing vascular anastomoses by trainees without any experience using purely laparoscopic versus robotic-assisted techniques. METHODS: Surgery residents were randomly included in the laparoscopic group (group A, n = 3) and the robotic group (group B, n = 3). They performed 10 end-to-end anastomoses on 18-mm-diameter tubular expanded polytetrafluoroethylene grafts. The parameters recorded were duration to complete the anastomosis and an indirect sealing quality evaluation (ISQE) defined as the following ratio: number of stitches with a distance of less than 4 mm/total number of stitches. RESULTS: The mean duration to perform the anastomosis decreased from 2340 s (±64) for the first anastomosis to 651 s (±248) for the last in group A (P < 0.05) and from 1989 s (±556) to 801 s (±120) in group B (P < 0.05). The mean ISQE increased from 74% (±18) for the first anastomosis to 98% (±3) for the last in group A (P < 0.05) and decreased from 100% to 98% (±2) in group B (nonsignificant). The mean duration to perform the first anastomosis was lower in group B than in group A (P < 0.05). The mean duration to perform the last anastomosis was not significantly different between the groups. Sealing tended to be better in group B for the first anastomosis compared with group A. CONCLUSIONS: Minimally invasive laparoscopic technique training demonstrates a learning curve to perform vascular anastomoses. The robotic-assisted technique tended to improve suturing skills and should be considered as a valuable tool to reduce the technical learning curve.

Relation between tensile tests and compliance in polyester textile vascular prostheses.

BACKGROUND: Compliance is one of the mechanical features of a vascular prosthesis (VP) that influences its performances. The goal of the present in vitro study was to attempt characterizing textile VP compliance through mechanical tests proposed in the standards. METHODS: Three different models of commercially available knitted VP (P1, P2, and P3) were studied using longitudinal and circumferential traction tests on coated and uncoated samples. Five samples of each model were considered for each test. The Young modulus was then calculated to indirectly predict the longitudinal and radial compliance of the VP. Moreover, actual compliance was measured on a specific device that regulates the intraluminal pressure of a fluid maintained in the tested VP at 37°C. VP dilatation under pressure load was measured with a digital camera system. RESULTS: The Young modulus variations from one VP to the other were compared with the differences between effective compliance values at radial, longitudinal, and volume level. Although the presented results show differences among the VP, one can observe that the graft materials' Young modulus and the compliance properties are linked together in general. CONCLUSIONS: Although VPs are subjected to multidirectional stresses ex vivo, unidirectional standard mechanical tests, through the measurement of the materials Young modulus, can help predicting their compliance, however, in a limited frame.

Non-Anastomotic Complete ePTFE Axillobifemoral Bypass Disruption and Thrombosis Following Shoulder Dislocation.

Complete disruption of an expanded polytetrafluoroethylene (ePTFE) vascular graft is rare. This is a report of a case of a 70 year old man presenting with left shoulder dislocation, which was reduced immediately. Two weeks later, the patient presented with Rutherford 2b bilateral lower limb ischaemia related to the thrombosis of an ePTFE axillobifemoral bypass. The graft was implanted five years earlier for treatment of an aorto-enteric fistula secondary to an infected aortobifemoral bypass. A non-anastomotic pseudoaneurysm associated with complete disruption of the ePTFE graft was found. Systematic analysis of the explant showed that the rupture occurred at the level of a ringed external support and that ongoing tears also occurred on the posterior wall of the graft at the level of this external support. In conclusion, complete analysis of failure mechanisms even from an isolated report is mandatory.

Systematic cervical approach for endovascular treatment of thoracic aortic diseases with debranching.

Endovascular treatment of thoracic aorta (TEVAR) often requires supra-aortic arterial trunks debranching to provide an acceptable proximal landing zone. To facilitate TEVAR procedures involving landing zones 1 to 3, we propose a systematic 4-step strategy with 1) a primary surgical cervical exposure of the supra-aortic trunks; 2) insertion through this access of a 5 Fr introducer in the first non-covered supra-aortic trunk to delineate precisely the landing zone; 3) followed by deployment of the thoracic endograft through one femoral access; 4) immediate completion of the surgical debranching, i.e. transposition or bypass.

Associated Da Vinci and magellan robotic systems for successful treatment of nutcracker syndrome.

Here, we report the case of a 26-year-old woman suffering from nutcracker syndrome with concurrent disabling pelvic congestion syndrome. She was given the minimally invasive treatment of left renal vein transposition with the Da Vinci(®) robotic system (Intuitive Surgical, Sunnyvale, CA), followed the next day by a gonadal vein and pelvic varicose embolization using a robotic intraluminal navigation with the Magellan™ robotic system (Hansen Medical, Mountain View, CA). The procedure was uneventful, and the patient had good results at 6 months of follow-up, including a patent left renal vein and complete relief of symptoms.