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Title: A randomised study comparing Vein Integrity and Clinical Outcomes (VICO) in open vein harvesting and two types of endoscopic vein harvesting for coronary artery bypass grafting
Author: Krishnamoorthy, Bhuvaneswari
Awarding Body: University of Manchester
Current Institution: University of Manchester
Date of Award: 2017
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Abstract:
Background: Coronary Artery Bypass Grafting (CABG) surgery is one of the most commonly performed surgical procedures to improve the symptoms of coronary artery disease. The Long Saphenous Vein (LSV) is typically used as a graft to bypass the blocked coronary arteries. The traditional way of harvesting the LSV is to make a long skin incision in the patient's leg. This technique has a high rate of incidence of wound complications and postoperative pain and poorer patient satisfaction. Endoscopic Vein Harvesting (EVH) techniques, introduced more than a decade ago, reduce these complications and improve quality of life. Findings regarding the safety and efficacy of EVH techniques and the quality of the vessel harvested by this technique are contradictory. Adoption of EVH techniques is still inconsistent globally and it is not completely accepted by all cardiac centres. Many studies are available in the literature measuring either histological outcome or clinical outcome in relation to different harvesting techniques. However, there remains no definitive randomised data available directly correlating harvesting-induced vein damage with clinical outcome. The aim of this Vein Integrity and Clinical Outcome (VICO) randomised trial was designed to assess the direct relationship between the histological damage caused during different methods of vein harvesting and clinical outcome post coronary artery bypass surgery. Methods: 100 patients were randomised in each group: Group 1 consists of closed tunnel CO2 endoscopic vein harvesting (EVH) (CT-EVH) and Group 2 consists of open tunnel CO2 EVH (OT-EVH) with the control Group 3 consists of standard open vein harvesting (OVH) with a total of 300 patients in this study. All the veins were harvested by an experienced practitioner who has performed >2000 OVH and >250 EVH. 1cm x 3 segments from three different parts of the vein were obtained for all patients (n=900). The histological levels of damage (endothelial and muscular layers) of the harvested vein and post clinical outcome for Major Adverse Cardiac Events (MACE) were measured using validated measuring tools. Health economic (cost effectiveness, EQ-5D) and health-related quality of life (SF-36) data were also recorded to assess the impact of these surgical techniques. Results: The level of endothelial disruption was greatest in the OT-EVH group in the proximal, distal and random samples (all p < 0.001). Internal muscle migration was greatest in OT-EVH compared to the other groups for proximal, distal and random samples (all p < 0.001). Smooth muscle circular layer detachment was observed on a much greater scale in the endoscopic groups compared to OVH in proximal (p=0.008), distal (p < 0.001) and random (p=0.001). Smooth muscle longitudinal layer detachment was consistent between groups in proximal (p=0.113) and distal (p=0.380) samples but was greater in endoscopic groups compared to OVH (p=0.012). Secondary clinical outcomes demonstrated no significant differences in composite MACE scores at 3, 6, 12, 18 and 24 months. The quality adjusted life in years (QALYs) gain per patient was: 0.11 (p < 0.001) for closed tunnel CO2 EVH and 0.07 (p=0.003) for open tunnel CO2 EVH compared with open vein harvesting. The likelihood of being cost-effective, at a pre-defined threshold of £20,000 per QALYs gained was: 75% for closed tunnel EVH, 19% for open tunnel EVH and 6% for open vein harvesting. Conclusion: In this study, open vein harvesting was associated with better preservation of vein layers in non-distended proximal samples than endoscopic vein harvesting. Both EVH groups displayed some degree of histological damage; OT-EVH was associated with more endothelial disruption. Clinical outcomes suggest that histological findings do not directly contribute to MACE outcomes. Gains in health status were observed and cost-effectiveness was better with CT-EVH compared with the other two surgical techniques. These results suggest that EVH can be utilised safely, but with careful selection of patients.
Supervisor: Caress, Ann-Louise Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID: uk.bl.ethos.713592  DOI: Not available
Keywords: Endoscopic vein harvesting ; Coronary artery bypass grafting ; Vein harvesting
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