Creation of a tricuspid valve regurgitation model from tricuspid annular dilatation using the cardioport video-assisted imaging system

BACKGROUND AND AIM OF THE STUDY: Experimental models of tricuspid valve regurgitation (TR) are used to study novel annuloplasty techniques (including prosthetic rings), and they can also serve as physiologic models to investigate TR pathophysiology. The study aim was to develop an appropriate simple and reproducible experimental model of TR from annular dilatation.

METHODS: Acute TR was successfully created through multiple small 3- to 5-mm incisions in the annulus using a custom-made optical port with an instrument shaft (the Cardioport) that accepts a standard endoscopic imaging system. The Cardioport was inserted, via a thoracotomy, through the right atrium of seven Yorkshire pigs, and directed towards the tricuspid valve annulus to create the annular incisions. Tricuspid valve anatomy and function were evaluated using 2D and 3D echocardiography. The presence and severity of TR, annulus diameter, and changes in heart rate and atrial pressures after making the annular incisions were documented. To monitor tricuspid annular dilatation and the progression of TR, follow up echocardiography and color Doppler examinations were performed at two and eight weeks postoperatively.

RESULTS: The acute onset of TR was well tolerated, and there were no deaths or significant morbidity associated with the procedure. The annular diameter was increased from a preoperative mean of 23.1 +/- 1.7 mm, to 32.2 +/- 2.5 mm at two weeks postoperatively, and to 37.3 +/- 3.6 mm at eight weeks postoperatively. Overall, the TR progressed from mild (grade I) to severe (grade III) in all of the animals.

CONCLUSION: This novel porcine model represents a relatively simple and a reproducible surgical technique for the creation of annular dilatation and TR, and may also serve as a chronic model of the latter condition.