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The Hatle orifice area formula tested in normal bileaflet mechanical mitral prostheses
J Chambers1, P Deverall, G Jackson
1Department of Cardiology, Guy's Hospital, London, UK.
International Journal of Cardiology
|June 1, 1992
Summary
The Hatle formula is not reliable for assessing normal bileaflet mitral valve prostheses. Pressure half-time in these valves correlates better with non-prosthetic factors than orifice area.
Area of Science:
- Cardiology
- Biomedical Engineering
- Prosthetic Valve Research
Background:
- The Hatle formula, derived for native mitral stenosis, may not accurately assess prosthetic valves.
- Bileaflet mechanical prostheses have predictable orifice areas, suggesting effective and manufacturer areas should align.
Purpose of the Study:
- To evaluate the applicability of the Hatle formula for assessing the effective orifice area of normal bileaflet mitral prostheses.
- To determine the correlation between the Hatle formula-derived area and the measured manufacturer's area in CarboMedics prostheses.
Main Methods:
- Studied 60 patients with CarboMedics bileaflet mitral prostheses.
- Calculated stroke volume using subaortic velocity trace and left ventricular outflow tract area.
- Averaged diastolic measurements over 5 beats for analysis.
Main Results:
- No significant correlation was found between the Hatle formula area (3.1 +/- 0.7 cm2) and measured area (2.8 +/- 0.4 cm2) (p = 0.329).
- Pressure half-time showed closer correlation with peak transmitral velocity, RR interval, diastolic time interval, and stroke volume than with orifice area.
Conclusions:
- The Hatle formula is inappropriate for normal bileaflet mitral prostheses.
- Pressure half-time in these prostheses is influenced more by non-prosthetic factors than the actual orifice area.