Clinical Update Thirty-Two: Mechanical Over Tissue

The advantage of mechanical over tissue prostheses in mitral patients

A comprehensive study of mitral valve repair vs. mitral valve replacement reveals that the least acceptable outcomes occur in tissue valve mitral replacement patients.

 

Clinicians at Duke University in North Carolina published a study that shows an expected advantage in survival for patients with mitral valve repair vs. mitral valve replacement.1 This study of 989 patients also reveals a startling advantage in survival for mechanical mitral valve patients over tissue mitral valve replacement. To quote the authors, “. . . firm conclusions cannot be made about the relative merits of mechanical versus tissue valves, but the poor outcomes observed in the tissue valve cohort raises serious questions. This topic should be investigated further . . . .” In a related presentation at the Southern Thoracic Surgical Association in 2009, the authors presented data to show that at any age, survival for mechanical mitral valve patients is significantly greater than that for patients with tissue mitral valves.2

Since 1994, the number of mitral valve repairs has risen dramatically while replacement has decreased. But there remain patients who cannot be repaired. For these patients based on this data, mechanical replacement is preferable.

The On-X® Prosthetic Heart Valve is offered in the mitral position with two cuff configurations. Cuff designs include sized cuffs (standard model, sizes 25, 27/29 and 31/33) and the Conform-X model (size 25-33) which fits almost every patient needing mitral replacement. This valve is optimally sized at its nominal “25 size” where the outer diameter of the valve body measures 25mm and the sewing cuff outer diameter measures greater than 33mm. There is only one larger geometric orifice area in the industry for mitral valves which offers no better hemodynamic performance.3

A comparative clinical study from the Ottawa Heart Institute found the On-X mitral valve performance to be favorable to other bileaflet mechanical valves.3 This study showed less mitral mismatch for the On-X valve leading to greater survival and less heart failure.

An independent study found the 25-33 On-X mitral valve with Conform-X cuff to be useful and easy to implant.4 The Conform-X cuff design provides the additional benefit of reduced space requirements.

Doesn’t it make sense to offer the best mechanical valve to mitral valve patients when repair is not possible? The best opportunity for greater survival, less mismatch and lower complication rates—On-X mitral valves!

 

References

  1. Daneshmand MA, Milano CA, Rankin JS, et al. Mitral valve repair for degenerative disease: A 20-year experience. Ann Thorac Surg 2009:88:1828-37.
  2. Daneshmand MA, Milano CA, Rankin JS, et al. Influence of patient age on procedural selection in mitral surgery. Presentation at the Southern Thoracic Surgical Association, Nov. 2009, and Ann Thorac Surg, in press.
  3. Lam BK, Chan V, Hendry P, et al. The impact of patient-prosthesis mismatch on late outcomes after mitral valve replacement. J Thorac Cardiovasc Surg 2007;133:1464-73.
  4. Wippermann J, Albes JM, Madershahian N, et al. Three years’ experience with the On-X Conform-X bileaflet prosthesis for ‘atrialized’ mitral valve replacement: A preliminary report. J Heart Valve Dis 2005;14:637-43.
  5. On-X® Prosthetic Heart Valve. Summary of Safety and Effectiveness Data submitted to the United States Food and Drug Administration. PMA P000037. Approval date May 30, 2001 and October 11, 2002.
  6. Emery RW, Krogh CC, Arom KV, et al. The St. Jude Medical cardiac valve prosthesis: A 25-year experience with single valve replacement. Ann Thorac Surg 2005;79:776-82.
  7. CarboMedics® Prosthetic Heart Valve. Summary of Safety and Effectiveness Data submitted to the United States Food and Drug Administration. PMA P900060. Approval date April 13, 1993.
  8. ATS Open Pivot® Bileaflet Heart Valve. Summary of Safety and Effectiveness Data submitted to the United States Food and Drug Administration. PMA P990046. Approval date October 13, 2000.
  9. SJM Biocor® Valve and SJM Biocor® Supra Valve. Summary of Safety and Effectiveness Data submitted to the United States Food and Drug Administration. PMA P040021. Approval date August 5, 2005.
  10. Mosaic Heart Valve. Summary of Safety and Effectiveness Data submitted to the United States Food and Drug Administration. PMA P990064. Approval date July 14, 2000.
  11. Marchand MA, Aupart MR, Norton R, et al. Fifteen-year experience with the mitral Carpentier-Edwards Perimount pericardial bioprosthesis. Ann Thorac Surg 2001; 71:S236-39.

 

On-X aortic and mitral valves are FDA approved. Not all On-X valve models are available in all markets.
CAUTION: Federal law restricts this device to sale by or on the order of a physician. Refer to the Instructions for Use that accompany each valve for indications, contraindications, warnings, precautions and possible complications. For further information, visit www.onxlti.com.

 

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