Implantation of a modified stented bovine pulmonary valve in a beating heart sheep model

The Sheep as a Large Animal Model for the Investigation and Treatment of Human Disorders

Simple Summary

We review the value of large animal models for improving the translation of biomedical research for human application, focusing primarily on sheep.

Abstract

An essential aim of biomedical research is to translate basic science information obtained from preclinical research using small and large animal models into clinical practice for the benefit of humans. Research on rodent models has enhanced our understanding of complex pathophysiology, thus providing potential translational pathways. However, the success of translating drugs from pre-clinical to clinical therapy has been poor, partly due to the choice of experimental model. The sheep model, in particular, is being increasingly applied to the field of biomedical research and is arguably one of the most influential models of human organ systems. It has provided essential tools and insights into cardiovascular disorder, orthopaedic examination, reproduction, gene therapy, and new insights into neurodegenerative research. Unlike the widely adopted rodent model, the use of the sheep model has an advantage over improving neuroscientific translation, in particular due to its large body size, gyrencephalic brain, long lifespan, more extended gestation period, and similarities in neuroanatomical structures to humans. This review aims to summarise the current status of sheep to model various human diseases and enable researchers to make informed decisions when considering sheep as a human biomedical model.

Late results of right ventricular outflow tract reconstruction with a bicuspid expanded polytetrafluoroethylene valved conduit

BACKGROUND AND AIM TO READ

We report the results of a bicuspid expanded polytetrafluoroethylene (ePTFE) valved conduit used for right ventricular outflow tract reconstruction (RVOTR).

METHODS

Between November 2005 and February 2009, 12 conduits were used for RVOTR. The mean age and weight of patients were 43.5 ± 46.4 months and 13.4 ± 8.6 kg. The main diagnosis was tetralogy of Fallot with pulmonary atresia in eight patients. The most common conduit size was 18 mm. The mean follow-up was 88.0 ± 35.9 months.

RESULTS

There were no operative and late mortalities. At discharge, the mean peak systolic pressure gradient across the RVOT was 14.1 ± 11.3 mmHg. There was no conduit valve regurgitation in nine patients. At the latest echocardiography (mean follow-up: 84.3 ± 35.5 months), the mean peak systolic pressure gradient across the RVOT was 59.7 ± 20.2 mmHg, and there was no conduit valve regurgitation in six patients. Freedom from conduit malfunction was 100% and 83.3%, at 1 and 8 years, respectively. Two conduits were explanted due to sternal compression and four from conduit malfunction. Freedom from explantation was 83.3% and 74.2% at 2 and 8 years, respectively.

CONCLUSIONS

ePTFE bicuspid valved conduit has good late function in terms of valve regurgitation, but the pressure gradient across the conduit increases with time, which is the main cause of conduit failure and explantation.