Multi-Scale Modelling of Textile Reinforced Tissue Engineered Heart Valves
Transcatheter aortic valve implantation of fibrin-based tissue engineered heart valves with a tubular leaflet construct have been developed as an alternative to invasive traditional surgical heart valve implantation, but currently need reinforcement to withstand pressures found in the aortic position. To increase valve strength, a PET textile reinforcement has been introduced to the fibrin scaffold. However, care must be taken when using a textile reinforcement. Increasing reinforcement may increase the strength, but also increases stiffness which can interfere with the functionality of the valve, prohibiting full valve closure. In order to predict the behavior of the valve, improve design, and eventually optimize valve performance by tailoring the textile reinforcement, a 4-tiered hierarchical multi-scale modelling framework has been created. The model includes an individual fiber scale model, two textile-level models, and a full heart valve model. Geometry generation based on microscopic images of the composite will be discussed, along with application of boundary conditions and loading application. Fitting the various material models based on homogenization of the smaller scale will be demonstrated. Finally, experimental validation and characterization at various scales will be discussed.
Innovations in therapies for heart valve disease.
The burden of heart valve disease among adults is enormous in the developed world. Increased life expectancy and age-related valvular degeneration remain the predominant contributors to heart valve dysfunction, which if uncorrected lead to congestive heart failure and increased morbidity and mortality. Clinical evidence on the detrimental impact of valve disease on both pediatric and adult populations has fueled growing interest in diagnosis and therapy for heart valve disease, and also significant financial investment from hospitals and medical device manufacturers in hybrid operating rooms and novel medical device technologies. A wide array of surgical, minimally invasive and percutaneous heart valve technologies are available today, which have significantly enlarged the surgeon's armamentarium, and revolutionized the traditional role of a surgeon in correcting such lesions. Amid this revolution in heart valve technologies, we present recent advances in heart valve therapies, critically appraise their clinical need, and finally discuss the clinical experience and outcomes of some of these technologies. The expected outcome of this review is to provide the clinical reader with a reasonable scientific basis to enable appropriate adoption of these technologies into their clinical practice.
Complex thoracic vascular injury repair using deep hypothermia and circulatory arrest.
A 61-year-old man with a penetrating injury to the innominate artery, left common carotid artery, and left subclavian artery at their origins from the aortic arch with associated injuries to both innominate veins and an innominate artery to vein fistula after a single stab wound is described. The patient was managed successfully using cardiopulmonary bypass together with deep hypothermia and circulatory arrest. Presentation and management are discussed.