A Translational 'Humanised' Porcine Model for Trans-Septal Mitral Valve Interventions: the Right Pulmonary Vein Approach.

There is an important need to develop a transcatheter/trans-septal-like model which will allow deliverability of mitral valve devices at the right angulation and height above the mitral annulus similar to the human patient. A ministernotomy allowing for TEE probe to be introduced transpericardially was performed in seven animals. In three, a standard trans-septal approach was used to attempt to deliver a device to the level of the mitral plane with a human delivery system. In four cases, a Dacron tube was connected to the RPV and the device introduced to the LA. Under TEE equivalent imaging, the device was then successfully steered to the mitral plane in all cases, having failed in all trans-septal attempts. A combination of transpericardial echocardiographic imaging (TPE) and RPV approach to the LA facilitated successful human-like mitral valve device implantation.

Transpericardial 3D Echocardiography in the Sheep Model, Facilitating Real Time Anatomical Assessment for Planning and Guiding Transcatheter Mitral Valve Replacement and Repair.

INTRODUCTION: Symptomatic mitral regurgitation (MR) is associated with high morbidity and mortality which can be ameliorated by surgical valve replacement or repair. Despite this, many patients are excluded from surgery. Transcatheter mitral repair and replacement has emerged as a promising therapeutic option for the treatment of severe MR. The majority of these procedures rely on high definition three dimensional (3D) transesophageal echocardiographic (TEE) real time imaging. The sheep model is the model of choice for preclinical studies of transcatheter mitral valve (MV) replacement and repair. However due to the thoracic conformation TEE studies in those animals are suboptimal. METHODS AND RESULTS: In this study we tested and compared the feasibility of conventional TEE and newly described transpericardial 3D echocardiography (TPE) for assessment of the MV as a tool to plan and possibly guide transcatheter/transapical procedures in the sheep model. The conventional TEE was challenging and produced incomplete data in all of the animals. In contrast, the TPE method clearly depicted the left atria and ventricle, MV apparatus, LVOT, aortic valve and proximal ascending aorta facilitating high resolution 3D rendering in all of the animals. CONCLUSION: The value of TEE in the sheep model is limited and could not be reliable for complete assessment of the LV and mitral valve apparatus. Whereas, TPE produce reliable and similar imaging to TEE in the human patients which could allow animal testing of devices designed to be delivered in humans.

Biocompatibility and Systemic Safety of a Novel Implantable Annuloplasty Ring for the Treatment of Mitral Regurgitation in a Minipig Model.

Prosthetic annuloplasty rings are a common treatment modality for mitral regurgitation, and recently, percutaneous implantation techniques have gained popularity due to their favorable safety profile. Although in common use, biocompatibility of annuloplasty rings has been reported only sparsely in the literature, and none of these reports used the percutaneous technique of implantation. We report on the biocompatibility and the systemic safety of a novel transcatheter mitral valve annuloplasty ring (AMEND™) in 6 minipigs. This device is composed of a nitinol tube surrounded by a braided polyethylene terephthalate fabric tube. The device produced no adverse inflammatory response, showing gradual integration between the metal ring and the fabric by normal host fibrocellular response, leading to complete neoendocardium coverage. There was no evidence for adverse reactions, rejection, or intolerance in the valvular structure. In 2 animals, hemopericardium resulted from the implantation procedure, leading to right-sided cardiac insufficiency with pulmonary edema and liver congestion. The findings reported herein can serve as a case study for the expected healing pathology reactions after implantation of transcatheter mitral valve annuloplasty rings.

The effect of positioning on the appearance of selected cranial thoracic structures in the dog.

In this retrospective study the effect of thoracic positioning on the visibility and size of selected cranial thoracic structures in dogs was investigated. Dorsoventral (DV), ventrodorsal (VD) as well as left lateral recumbent (LLR) and right lateral recumbent (RLR) thoracic radiographs of 17 large, 15 medium, and 10 small skeletally mature dogs were evaluated. The craniodorsal and cranioventral mediastinum, the cupula pleura and sternal lymph nodes were examined. The effect of obesity was also evaluated. The craniodorsal mediastinum was better delineated on DV radiographs and was wider on VD radiographs. The craniodorsal mediastinal width: width of T2 cranial end-plate on VD radiographs was 2.41 for all groups combined and obesity significantly influenced this value. The cranioventral mediastinum was more visible in RLR and VD radiographs. A normal sternal lymph node soft tissue opacity was seen most commonly in RLR in large breed dogs and had a mean length of 30 mm. The pulmonary cupula extended beyond the first rib on all views and extended more cranially and was better visualised on VD than DV views.