Partial Hammock Valve: Surgical Repair and Long-Term Follow-Up in 23 Patients

In 2006, we reported a "forme frustrée" of hammock valve involving the posterior mitral leaflet resulting in restricted leaflet motion and mitral regurgitation. The purpose of this retrospective report is to describe the surgical techniques and long-term outcome of 23 patients with partial hammock valve who underwent successful repaired over a 22-year period (1995 to 2017).

Partial hammock valve is defined as anomalous papillary muscles that have hypertrophied and fused together. There are three or four papillary muscles implanted high on the posterior wall, forming a palisade under the posterior leaflet. Twenty-three patients were operated on, 19 adults and 4 children. In all but 3 patients, repair consisted of posterior leaflet enlargement of the P2 and P3 segments with a semilunar patch of bovine pericardium. The fused papillary muscles were split longitudinally, and some secondary chordae were cut. All adult patients received a prosthetic ring.

A satisfactory repair was achieved in all patients. Mean age at the time of operation was 62 ± 11 years (range, 6 days to 79 years). Hospital mortality occurred in 1 patient (1 of 23; 4.3%). Mean follow-up was 7 years (range, 1 to 22). Actuarial survival rate at 7 years was 70%. At last echocardiogram, all survivors were free from mitral regurgitation grade II or higher. There was no reoperation.

Partial hammock valve is a rare congenital anomaly resulting in mitral regurgitation. Patch enlargement of the posterior leaflet achieves long-term repair. It is safe and reliable.