The QuantumCor device for treating mitral regurgitation: an animal study.

OBJECTIVES: The mitral annular contraction achieved could help reduce mitral regurgitation (MR), and with appropriate modifications, be applied to human subjects providing a potentially effective percutaneous method of valve repair.

BACKGROUND: MR is an important source of morbidity and is an independent predictor of mortality. A variety of percutaneous approaches are being developed to address this issue. We introduce a novel potential method utilizing radiofrequency (RF) energy to heat and shrink the mitral valve annulus in an animal model.

METHODS: In open-heart procedures in 16 healthy sheep (six with naturally occurring MR), we used a malleable probe (QuantumCor, Lake Forest, CA) that conforms to the annular shape to deliver RF energy via a standard generator to replicate a surgical mitral annular ring. Seven sheep were followed chronically and their mitral annulus dimensions measured serially.

RESULTS: All sheep underwent intracardiac echocardiography or direct circumferential measurement of the mitral annulus before and after RF therapy. RF therapy was administered in less than 4 min in each case, and the mean anteroposterior (AP) annular distance was reduced by a mean of 23.8% (AP diameter reduction 5.75 +/- 0.86 mm, P < 0.001) acutely. In the six sheep with nonischemic MR, regurgitation was eliminated. Acute histopathology (HP) demonstrated no damage to the leaflets, coronary sinuses, or coronary arteries. At the end of the intended 6-month period of the chronic part of the study, four of the seven animals survived. The four treatment animals showed significant reductions in mitral A-P dimension, with a percent diameter reduction of 26.4% (AP diameter reduction 7 +/- 2.3 mm).

CONCLUSION: The application of RF directly to heat the mitral annulus has resulted in sustained contraction of the annulus in this limited preclinical animal study. With further study and possible modifications, it holds promise for future application in human subjects with MR.