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

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.

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).

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.

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.