ABSTRACT
Background & objectives: Vascular illnesses are on the rise in India, due to increase in lifestyle diseases and demographic transition, requiring intervention to save life, organ or limbs using vascular prosthesis. The aim of this study was to develop indigenous large diameter vascular graft for treatment of patients with vascular pathologies. Methods: The South India Textile Research Association, at Coimbatore, Tamil Nadu, India, developed seamless woven polyester (Polyethylene terephthalate) graft at its research wing. Further characterization and testing followed by clinical trials were conducted at Sree Chitra Tirunal Institute for Medical Sciences and Technology, Thiruvananthapuram, Kerala, India. Fifteen in vivo experiments were carried out in 1992-1994 in pigs as animal model. Controlled (phase I) clinical trial in ten patients was performed along with control graft. Thereafter, phase II trial involved 22 patients who underwent multi-centre clinical trial in four centres across India. Results: Laboratory testing showed that polyester graft was non-toxic, non-leeching and non-haemolytic with preserved long-term quality, further confirming in pigs by implanting in thoracic aorta, comparable to control Dacron grafts. Perigraft incorporation and smooth neointima formation which are prime features of excellent healing characteristics, were noted at explantation at planned intervals. Subsequently in the phase I and II clinical trials, all patients had excellent recovery without mortality or device-related adverse events. Patients receiving the test graft were followed up for 10 and 5 years, respectively. Serial clinical, duplex scans and CT angiograms performed periodically confirmed excellent graft performance. Interpretation & conclusions: Indigenously developed Chitra vascular graft was comparable to commercially available Dacron graft, ready for clinical use at affordable cost to patients as against costly imported grafts.
ABSTRACT
OBJECTIVE: To evaluate the performance of a biodegradable polymer based rapamycin-eluting coronary stent in a porcine model and demonstrate its safety and efficacy in the treatment of patients with de novo coronary stenosis. BACKGROUND: The indefinite presence of the polymer after the implantation of drug-eluting stents may initiate and sustain inflammation and contribute to the occurrence of late complications. METHODS: Seven study stents and 5 polymer-coated (control) stents were implanted in porcine carotid arteries. Histomorphometric analysis was performed 8 weeks after stent implantation. After establishing the safety of the stent in the animal model, a single-center, non-randomized study in patients with de novo coronary artery lesions was performed. Forty-nine stents were implanted in 43 patients. The 6-month clinical follow-up was 91% (39/43) and angiographic follow-up was 67% (29/43). The primary safety endpoint was the occurrence of 30-day major adverse cardiovascular events (MACE) and the principal efficacy endpoint was the 6-month angiographic late loss and binary restenosis rate. RESULTS: In the porcine model, the study stent showed acceptably low injury, inflammation and fibrin scores. There was a quantitative reduction in neointimal hyperplasia which was not statistically different from the control stent. However, in the first-in-man evaluation, there was significant suppression of intimal growth as evidenced by an angiographic late loss of 0.28 +/- 0.45 mm at 6 months. The restenosis rate was 10.3% (3/297). There was no death, stent thrombosis or myocardial infarction at 30 days or at 6 months. The 6-month target lesion revascularization rate was 3.47 percent; (1/29). CONCLUSION: This preclinical and early clinical experience demonstrates the safety and efficacy of a novel biodegradable polymer-based rapamycin-eluting coronary stent.