On-X Life Technologies, Inc. (On-X LTI) was formerly
Medical Carbon Research Institute (MCRI).
Hemodynamics
Low Gradients
The On-X valve's hemodynamic performance is one of the very best among valve prostheses, particularly in smaller sizes. Table 1 compares the mean pressure gradients and maximum body surface area of the On-X valve size 19 with other competitors' valves fitting a 19mm annulus.
| 19 mm Annulus | Gradient (mmHg) |
EOA* (cm2) |
GOA** (cm2) |
BSA*** (m) |
|---|---|---|---|---|
| On-X Valve | 8.3 | 1.5 | 2.0 | 1.76 |
| SJM Regent | 9.7 | 1.6 | 1.96 | 1.88 |
| ATS 16/19 | 20.2 | 1.2 | 1.25 | 1.41 |
| CMI Supra-annular 21 | 16.2 | 1.3 | 1.46 | 1.53 |
| Medtronic Advantage 19 | 16.0 | 1.0 | not available | 1.18 |
| Medtronic Freestyle | 12.0 | 1.1 | not available | 1.29 |
| Edwards Perimount | 22 | 0.82 | not available | 0.96 |
| *Effective Orifice Area **Geometric Orifice Area (leaflets in place) ***Body Surface Area (accommodated without patient mismatch, based on 0.85 EOA index) |
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Intra-Annular Flared Walls Preserve
Hemodynamic Benefit
The On-X valve hemodynamics benefit extend beyond outstanding gradients. While many valves vacate the annulus to increase orifice area, the On-X valve extends through the annulus, protecting against ingrowth to preserve the full geometric orifice area of the valve over time.
The Thrill is Gone!
With On-X aortic valves, surgeons report an absence of a “thrill” within the aorta of implanted patients.
What Thrill?
Following implantation of an aortic valve prosthesis and removal of the cross-clamp, many surgeons pause to palpate the patient's aorta. This habit provides a tactile confirmation that the implanted valve is functioning properly. With bileaflet mechanical valves, surgeons report that they characteristically feel an unnatural “thrill” (vibration) in the aorta.
The absence of thrill with On-X valves is a further indication that efforts to reduce turbulence have met with success. On-X valves are designed to emulate the natural flow of the native valve with hemodynamic features like the inlet flare, thinner orifice walls, natural length and fully opening leaflets.
Best Overall Performance
The evolutionary new shape of the On-X valve is defined by sound fluid dynamic principles that reduce turbulence, pressure gradients and hemolysis. No other valve provides such comprehensive benefit to the patient's well-being.
References
1. Summary of Safety and Effectiveness, On-X® Prosthetic Heart Valve, FDA PMA P000037, May 30, 2001.
2. Bach DS, Goldbach M, Sakwa MP, et al. Hemodynamic and early clinical performance of the St. Jude Medical Regent mechanical aortic valve. Ann Thorac Surg. 2002;74:2003-09.
3. Vitale N, Caldarera I, Muneretto C, et al. Clinical evaluation of St. Jude Medical Hemodynamic Plus versus standard aortic valve prostheses: the Italian multicenter, prospective, randomized study. J Thorac Cardiovasc Surg. 2001;122:691-98.
4. Summary of Safety and Effectiveness, ATS Open Pivot® Bileaflet Heart Valve, FDA PMA P990046, October 13, 2000.
5. Summary of Safety and Effectiveness, Carbomedics® Prosthetic Heart Valve, FDA PMA P900060, September 29, 1993.
6. Koertke H. Worldwide clinical performance of the Medtronic Advantage® prosthetic heart valve in the aortic position. J Cardiovscular Surg. 2003;44(5-S1):52.
7. Summary of Safety and Effectiveness, Medtronic Freestyle® Aortic Root Bioprosthesis, Model 995, FDA PMA P970031, November 26, 1997.
8. Banbury MK, Cosgrove DM, Thomas JD, et al. Hemodynamic stability during 17 years of the Carpentier-Edwards aortic pericardial bioprosthesis. Ann Thorac Surg. 2002; 73:1460-65.
9. Pibarot P, Dumesnil JG. Patient-prosthesis mismatch and the predictive use of indexed effective orifice area: is it relevant? Cardiac Surgery Today. 2003;1(2):43-51.
10. Chafizadeh ER, Zoghbi WA. Doppler echocardiography assessment of the St. Jude Medical prosthetic valve in the aortic position using the continuity equation. Circulation. 1991;83: 213-23.