Subscribe to RSS
DOI: 10.1055/s-2006-925617
Value and limitations of valvular resistance to estimate homograft performance following the Ross procedure
Aims: Reconstruction of the (RVOT) in Ross procedures results in some patients in mild to moderate conduit stenosis due to degenerative changes of the pulmonary homograft. This study was conducted to determine the utility of RVOT resistance in assessing the severity of outflow impairment.
Methods: 385 pts (306 m, 79 f, mean age 46.6±12.9 y) have been investigated at a mean of 2.9±2.5 y following the autograft procedure. Effective orifice area (EOA), flow rate (F), maximal/mean pressure gradients (dPmax/mean) and valve resistance (R) were assessed by Doppler echocardiography. Indexed effective orifice area (EOAI) was assumed to be the reference measurement of the degree of the obstruction. Therefore, at last follow-up, two groups were analysed: group I (EOAI>0.85cm2/m2) and group II (EOAI<0.85cm2/m2)
Ergebnisse: At the time of implantation EOAI of the total group was 0.92±0.4cm2/m2, dPmax/mean 19.7±9.6/9.4±5.6mmHg and valvular R of 65.5±36.4 dynes×s×cm-5, respectively. At latest follow-up EAOI and dPmax/mean were significantly different in both groups: Group I: EOAI 1.22±0.39cm2/m2, dPmax/mean 17.0±8.1/8.8± 4.6mmHg vs. group II: EOAI 0.67±0.15cm2/m2, dPmax/mean 21.5±10.0/11.4±5.9mmHg (p<0.05). Valve resistance increased less with flow in group I (R 46.7±24.9 dynes×s×cm-5) compared to group II (R 78.8±36.4 dynes×s×cm-5).
Conclusions: In RVOT grafts following the Ross procedure, homograft resistance is strictly flow dependent in patients with calculated EOAI<0.85cm2/m2. In EOAI>0.85cm2/m2 there is only a weak impact of flow in the resulting resistance. This may be due to remaining compensatory elastic properties of the conduit with increasing flow rates in this group, whereas in EOAI <0.85 increasing transvalvular flow led to a more pronounced resistance.