Reoperations for left-sided low-profile mechanical prosthetic obstructions.

A series of 2,474 hospital survivors of primary mitral, aortic, and double mitral-aortic valve replacement were observed for a cumulative period of 11.945 years (mean, 4.2 years; range, 0.6-14 years). The linearized incidences of reoperations for thrombotic obstructions were 0.33 +/- 0.08% for mitral valve replacement, 0.36 +/- 0.1% for aortic valve replacement, and 0.42 +/- 0.1% for double valve replacement (p = not significant). Forty-one patients (16 mitral, 12 aortic, and 13 double valve replacements) underwent a total of 44 reoperations with a mean interval of 36 +/- 29 months (range, 0.25-85 months) between operations. Diagnosis was established invasively only in 13 patients (30%). Hospital mortality at reoperation was 18% (8 patients); 28 patients (63%) required emergency surgery. The choice surgical procedures were thrombectomy for clotted aortic prostheses (18 of 24) and valve replacement for obstructed mitral valves (22 of 25; p less than .001). Rethrombosis occurred in 3 patients (1 aortic and 2 double valve replacements). At hospital admission 17 patients (38%) had prothrombin times outside therapeutic ranges (between 20 to 30% of the normal value). The incidence of reoperations for thrombosis in low-profile mechanical prostheses was unaffected by valvar position and number of prostheses implanted. Rethrombosis occurred only in previously cleaned valves, although its occurrence was not significant. The present results indicate that, as experience is gained in the diagnosis and surgical management of this complication, hospital mortality can be reduced significantly (from 37% to 4%).