Excellent mid-term durability of the On-X mechanical aortic valve in the pulmonary position with a low international normalized ratio.

Background And Aim Of The Study: Although the pulmonary position has been preferred for the placement of homografts or bioprosthetic valves, the limited longevity of these implants makes reoperation almost unavoidable. Good durability of mechanical valves in the pulmonary position has been reported. The mid-term outcomes were analyzed of patients who received an On-X mechanical heart valve for pulmonary valve replacement (PVR) with a relatively low International Normalized Ratio (INR).

Methods: Between February 2008 and February 2011, mechanical On-X valves (size range: 19 to 25 mm) were implanted for PVR in six patients. Tetralogy of Fallot (ToF) was the most common diagnosis (n = 6). Postoperatively, warfarin was used to maintain the INR at 1.5-2.0. The surgical results and follow up were reviewed retrospectively, with valve failure, thrombosis, embolism, bleeding, reoperation and death being defined as end-points.

Results: There was no intraoperative or in-hospital mortality. The mean age of patients at the time of PVR was 31 +/- 19.7 years (range: 16-61 years). In patients who underwent repair of ToF (n = 4) the average duration between PVR and previous right ventricular outflow tract (RVOT) reconstruction was 8.75 +/- 3.3 years (range: 5-12 years). The mean follow up period was 3.13 +/- 1.31 years (range: 2-5 years). There was no 30-day mortality, late death, thromboembolism, major bleeding event or valve dysfunction, and no patient needed reoperation. All survivors were categorized as NYHA class I or II.

Conclusion: A three-year experience with the On-X bileaflet mechanical valve in the pulmonary position demonstrated excellent mid-term durability, with no thromboembolisms or bleeding events when the INR was maintained at 1.5-2.0. For patients who require PVR, either as primary procedure or reoperation, the On-X mechanical heart valve might represent an appropriate option.