A novel technique for functional mitral regurgitation therapy: Mitral annular remodeling

Background. Functional mitral regurgitation (MR) plays a pivotal role in the pathophysiology of congestive heart failure, a major cause of cardiac morbidity and mortality. We have developed a mitral annular remodeling procedure through injection of a nonabsorbable substance into the periannular tissue of the posterior mitral annulus to reduce the mitral annular dimension in the septal-lateral axis. The purpose of this study is to describe a novel procedure for treatment of functional MR and report its effects on the geometry of the mitral annulus and degree of MR. Methods. Seven preliminary studies were performed using an epicardial approach in a healthy dog model to establish the feasibility of this injection procedure. Unexpectedly, 2 of 7 healthy dogs had a functional MR of grade 1 to 2+. In these 2 cases, the hemodynamic, angiographic, and echocardiographic assessments were conducted. Results. A nonabsorbable substance injection was successfully performed on a beating heart without instability of hemodynamics or any evidence of myocardial ischemia in all 7 dogs. In the 2 dogs with a functional MR, it was confirmed that the septal-lateral dimension decreased from 3.2 +/- 0.2 to 2.6 +/- 0.5 cm and the observed MR was reduced (MR area from 1.2 +/- 0.1 to 0 cm(2)) without any adverse effects on hemodynamics or coronary circulation (circumflex artery flow, 36.5 +/- 0.4 to 40.5 +/- 0.1 mL/min). Conclusion. Off-pump mitral annular remodeling through substance injection may be one procedural option for treatment of functional MR.