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Blood velocity patterns after aortic valve replacement with a pulmonary autograft
D A Steinbrüchel1, J M Hasenkam, H Nygaard
1Department of Cardiovascular Surgery, Medical University of Lübeck, Germany.
Objective:
Besides several other advantages, aortic valve replacement with a pulmonary autograft may result in improved hemodynamic characteristics compared to other valve replacement procedures. However, this plausible assumption has never been verified. Therefore, the aim of this study was to determine turbulent blood velocity energies in the ascending aorta after aortic valve replacement with a pulmonary autograft.
Methods:
Blood velocity measurements were performed using a specialized pulsed Doppler ultrasound technique in the ascending aorta immediately after weaning from extracorporeal circulation. Six patients were included in the study. Determination of radial velocity components in 17 measuring points evenly distributed in the cross sectional area allowed computation of turbulence energies and a quantitative display of the spatial and temporal turbulence energy distribution during systole.
Results:
The maximum turbulence energies were below 13 N/m2 in all patients and in all measuring positions in the cross sectional area. Color coded mapping of the spatial and temporal turbulence energy distribution displayed no consistent areas with markedly enhanced turbulence. These data are moderately elevated compared to turbulence energy values for normal aortic valves, which are below 4 N/m2, while artificial or xenovalves typically show values in the range of 40-60 N/m2.
Conclusions:
Turbulence energy levels after aortic valve replacement with a pulmonary autograft are considerably lower than those found for artificial aortic valves. From a fluid dynamic point of view this procedure provides excellent hemodynamic conditions in the ascending aorta.