Right papillary muscle sling: proof of concept and pilot clinical experience.

Objectives: Left-sided intraventricular remodelling by papillary muscle approximation associated with annuloplasty of the mitral valve improved outcomes for severe functional mitral regurgitation compared with annuloplasty alone. We conceived of, and studied, a papillary muscle sling on the right side of the heart associated with annuloplasty, seeking to reduce tricuspid valve tethering and right ventricular volumes and to preserve ventricular function.

Methods: An experimental model on ex vivo porcine hearts established the anatomical feasibility of the procedure. A first-in-man clinical series of 5 patients (3 men) with a mean age of 63.3 years (51-73) had mean right ventricular volumes of 320 ml (280-350) and 200 ml (155-250) in diastole and systole, respectively, and an ejection fraction of 30% (25-40). The mean pulmonary artery pressure was 60 mmHg (55-70), and all had Grade IV/IV tricuspid regurgitation (TR).

Results: There was no operative mortality. Post-repair, magnetic resonance imaging and echocardiographic studies showed mean right ventricle volumes of 165 ml (155-180) and 124 ml (110-140) in diastole and systole, respectively, and an ejection fraction of 28% (25-35) (P = 0.03). TR was <2, gradient across tricuspid valve was ≤ 4 mmHg and there was no right ventricular outflow tract obstruction. All patients were in New York Heart Association Class ≤ 2.

Conclusion: Intraventricular remodelling with a papillary muscle sling is safe and feasible on the right heart. Short-term follow-up shows that it ameliorates clinical functional status and improves valve competency through reduced tension and tethering of tricuspid leaflets.