Preclinical evaluation of hydrogel sealed fluropassivated indigenous vascular prosthesis.

Background & objectives: Polyethylene terephthalate (PET) graft, designed and developed at our institute for vascular reconstruction, is porous to promote optimal incorporation and neointima formation, requiring pre-clotting or biomodification by sealing the pores before implantation. The objective of this study was to characterize, test and perform preclinical evaluation of hydrogel (alginate dialdehyde cross-linked gelatin) sealed fluoropassivated PET vascular prosthesis in pig model, so as to avoid pre-clotting, for its safety and efficacy before employing the indigenous and less expensive graft for clinical use. Methods: Hydrogel sealed, fluoropassivated PET vascular prosthesis were tested for haemocompatibility and toxicity followed by small animal toxicology tests and in vivo experiments in pigs receiving implantation at thoracic aorta. All 33 animals received test as well as control grafts with a plan for phased explantation at 2, 12 and 26 weeks. All animals underwent completion angiogram at the end of procedure as well as before graft explantation. Results: Haemocompatibility tests for haemolysis and toxicity tests showed no adverse events in tested mice and rabbits. Completion angiogram showed intact anastamosis and patent graft in each animal in post-operative period and at explantation. Gross and histopathological examination showed well-encapsulated grafts, clean glistening neointima and no evidence of thrombus in both test and control grafts. Interpretation & conclusions: Hydrogel sealed, fluoropassivated PET vascular prosthesis was found non-toxic, haemocompatible and remained patent in in vivo studies at planned intervals.

The making of indigenous vascular prosthesis.

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.

Position statement from the Indian Society of Gastroenterology, Cardiological Society of India, Indian Academy of Neurology and Vascular Society of India on gastrointestinal bleeding and endoscopic procedures in patients on antiplatelet and/or anticoagulant therapy.

Antiplatelet and/or anticoagulant agents (collectively known as antithrombotic agents) are used to reduce the risk of thromboembolic events in patients with conditions such as atrial fibrillation, acute coronary syndrome, recurrent stroke prevention, deep vein thrombosis, hypercoagulable states and endoprostheses. Antithrombotic-associated gastrointestinal (GI) bleeding is an increasing burden due to the growing population of advanced age with multiple comorbidities and the expanding indications for the use of antiplatelet agents and anticoagulants. GI bleeding in antithrombotic users is associated with an increase in short-term and long-term mortality. In addition, in recent decades, there has been an exponential increase in the use of diagnostic and therapeutic GI endoscopic procedures. Since endoscopic procedures hold an inherent risk of bleeding that depends on the type of endoscopy and patients' comorbidities, in patients already on antithrombotic therapies, the risk of procedure-related bleeding is further increased. Interrupting or modifying doses of these agents prior to any invasive procedures put these patients at increased risk of thromboembolic events. Although many international GI societies have published guidelines for the management of antithrombotic agents during an event of GI bleeding and during urgent and elective endoscopic procedures, no Indian guidelines exist that cater to Indian gastroenterologists and their patients. In this regard, the Indian Society of Gastroenterology (ISG), in association with the Cardiological Society of India (CSI), Indian Academy of Neurology (IAN) and Vascular Society of India (VSI), have developed a "Guidance Document" for the management of antithrombotic agents during an event of GI bleeding and during urgent and elective endoscopic procedures.

Synchronous hybrid repair for ruptured aneurysm of bovine aortic arch.

Rupture of an aortic arch aneurysm is a life-threatening emergency with the risk of mortality escalating by the hour. We describe the successful hybrid repair of a ruptured bovine aortic arch aneurysm in a 75-year-old man, which involved aortic arch debranching by ascending aorta-bicarotid bypass followed by relining of the aortic lumen with a stent-graft. The procedure was not only lifesaving but also resulted in an active gentleman at 2-year follow-up. Considering the morbidity and mortality of open surgery using circulatory arrest, state-of-the-art synchronous hybrid repair seems to be an effective alternative for ruptured aortic arch aneurysms.

Chronic mesenteric ischemia and therapeutic paradigm of mesenteric revascularization.

Chronic mesenteric ischemia is a life-threatening clinical problem resulting in death from inanition and/or bowel infarction, if left untreated, albeit low disease prevalence. Typical presentation is postprandial abdominal pain, severe weight loss, and altered bowel habit. Surgical revascularization of the superior mesenteric artery provides effective long-term treatment for chronic intestinal ischemia. Eleven patients underwent superior mesenteric artery revascularization, nine of them with open retrograde superior mesenteric artery bypass and two with angioplasty and stenting. All patients except one made a satisfactory recovery in this cohort. Major complication included one graft thrombosis leading to bowel ischemia and death. The rest all recovered weight in 3-6 months with a follow up period of 6 to 28 months. Two patients had recurrence of symptoms due to failing bypass requiring stenting for assisted primary patency. Superior mesenteric artery revascularization can be performed with minimal morbidity and mortality, providing excellent symptom relief and quality of life.

Hybrid Strategy for Residual Arch and Thoracic Aortic Dissection following Acute Type A Aortic Dissection Repair.

Progressive dilatation of the false lumen in the arch and descending aorta has been encountered in one-third of survivors as a late sequelae following repair of ascending aortic dissection. Conventional treatment for the same requiring cardiopulmonary bypass and deep hypothermic circulatory arrest is associated with high morbidity and mortality especially in the elderly cohort of patients. Herein we report a case of symptomatic progressive aneurysmal dilatation of residual arch and descending thoracic aortic dissection following repair of type A aortic dissection, successfully treated by total arch debranching and ascending aortic prosthesis to bicarotid and left subclavian bypass followed by staged retrograde aortic stent-graft deployment. This case report with relevant review of the literature highlights this clinical entity and the present evidence on its appropriate management strategies. Close surveillance is mandatory following surgical repair of type A aortic dissection and hybrid endovascular procedures seem to be the most dependable modality for salvage of patients detected to have progression of residual arch dissection.