Animal Models of Mitral Regurgitation Induced by Mitral Valve Chordae Tendineae Rupture.

Background – Mitral regurgitation (MR) is a common valvular disease throughout the world. Various diagnostic techniques have been developed to assess the causes and severity of MR, and the therapeutic approaches to this disease have been widely documented. However, treatments for chronic MR remain controversial, and various animal models of chronic MR (including chordae tendineae rupture, rapid pacing and ischemia) have been developed to study the pathophysiology and therapeutic approaches to this disease. The objective of this paper is to review the animal MR models that have been developed using a mitral valve chordae tendineae rupture technique.
Animal models – Dogs and sheep have been the animals most commonly used in MR models induced by mitral valve chordae tendineae rupture, mainly due to considerations of cardiac size. Chordae tendineae cutting is performed using closed or open chest techniques. In the closed chest model, long flexible grasping forceps are positioned percutaneously in order to tear the mitral valve chordae. In the open chest model, cardiopulmonary bypass is performed and either selected chordae are cut under direct visualization, or a non specified number of chordae are cut using a metal device inserted through the left ventricular apex. Whatever the model used, MR has been found to become chronic 3 to 6 months after the induction of MR by chordae rupture. The reported mortality and complication rates of these models are high.
Conclusion – In the long term, experimental evolution of chronic MR is similar to the evolution occurring naturally in patients suffering from chronic MR. These models could thus be useful in understanding the disease better and in testing new therapeutic modalities. This review summarizes the physiological effects of each of these techniques and compares the advantages and disadvantages of each procedure.