Computational fluid dynamics analysis of endoluminal aortic perfusion.

INTRODUCTION: In peripheral percutaneous (VA) extracorporeal membrane oxygenation (ECMO) procedures the femoral arteries perfusion route has inherent disadvantages regarding poor upper body perfusion due to watershed. With the advent of new long flexible cannulas an advancement of the tip up to the ascending aorta has become feasible. To investigate the impact of such long endoluminal cannulas on upper body perfusion, a Computational Fluid Dynamics (CFD) study was performed considering different support levels and three cannula positions. METHODS: An idealized literature-based- and a real patient proximal aortic geometry including an endoluminal cannula were constructed. The blood flow was considered continuous. Oxygen saturation was set to 80% for the blood coming from the heart and to 100% for the blood leaving the cannula. 50% and 90% venoarterial support levels from the total blood flow rate of 6 l/min were investigated for three different positions of the cannula in the aortic arch. RESULTS: For both geometries, the placement of the cannula in the ascending aorta led to a superior oxygenation of all aortic blood vessels except for the left coronary artery. Cannula placements at the aortic arch and descending aorta could support supra-aortic arteries, but not the coronary arteries. All positions were able to support all branches with saturated blood at 90% flow volume. CONCLUSIONS: In accordance with clinical observations CFD analysis reveals, that retrograde advancement of a long endoluminal cannula can considerably improve the oxygenation of the upper body and lead to oxygen saturation distributions similar to those of a central cannulation.

A personalized approach to interventional treatment of tricuspid regurgitation: experiences from an acute animal study.

OBJECTIVES: Interventional treatment of tricuspid valve disease has so far received little attention due to the anatomical challenges in a thrombogenic surrounding. In the present study, we present an imaging-based, personalized interventional approach to the therapy of tricuspid regurgitation. METHODS: In our porcine model, we used rapid prototyping to build a matrix reproducing the geometry of the right atrium that was previously derived from computer tomography (CT) scans. Over this matrix, a braided nitinol device fitting almost completely the right atrium was crafted. An additional tubular stent component was developed to carry a tissue valve prosthesis. This part was designed to be connectable to the annular portion of the main device. In our feasibility study, the crimped device was implanted via jugular access into the right atrium of 12 pigs and expanded subsequently. Following isolated implantation of the device without the valve-carrying component, further procedures included implantation of the whole composite device, including the mentioned tissue valve. Representing a only feasibility study, all implantations were performed under full bypass and direct sight. On-site visualization was performed by both echocardiography and fluoroscopy. Additional imaging was realized by postoperative CT scans. RESULTS: Following implantation, 9 of 12 animals were weaned from cardiopulmonary bypass. Correct positioning of the device and orthodromic blood flow as maintained by the valve prosthesis were demonstrated by echocardiography and fluoroscopy. Postoperative contrast CT evaluation demonstrated proper fitting of the device into the right-sided heart cavities without obstruction of the outflow tract. Autopsy additionally confirmed its correct positioning without major trauma to surrounding structures. CONCLUSIONS: We demonstrated the feasibility in principle of a personalized interventional treatment for tricuspid regurgitation using a braided stent, based on individual cardiac imaging, with anchoring forces mainly exerted on the venae cavae and on the inner surface of the right atrium. The design process of this device is a good indicator of the growing potential of an imaging-based personalized simulation and production approach for the treatment of tricuspid valve disease.

A new approach to the interventional therapy of tricuspid regurgitation.

Currently, there are no fully developed interventional approaches for the treatment of tricuspid regurgitation (TR). The aim of this study was to evaluate the feasibility of orthotopic interventional placement of a biological prosthetic valve in the tricuspid position by inserting, with a transvenous approach, a self-expandable valve-bearing stent into the right atrium. Based on findings of computerized tomography (CT), a model of the porcine right heart was obtained. A self-expanding vascular endoprosthesis, carrying a prosthetic heart valve, was reshaped to fit the superior vena cava and the tricuspid annulus. Fenestrations were created to allow blood flow from the inferior vena cava and coronary sinus. This new device ("tricuspid endoprosthesis": TE) was implanted operatively into the superior vena cava, right atrium, and tricuspid annulus in six pigs. CT demonstrated proper fitting of the device, and echocardiography demonstrated correct positioning and function of the TE. Five animals were successfully weaned from cardiopulmonary bypass. Autopsy confirmed correct positioning of the TE without major trauma to surrounding tissues. These findings demonstrate a complete interventional approach for treating TR.