General Anesthesia (GA) and Mitral Regurgitation
GA has been proved to down grade the severity of MR due to its unloading
effect on the LV[21-23]. In addition, the severity
of MR may vary as the result of the dynamic nature of intraoperative
conditions[4]. MR is a valvular pathology affected
by multiple variables such as preload, LV contractility, heart rhythm,
afterload, GA and positive pressure
ventilation[24,25].Alijandro G, et al. had
done a experiment that a baseline intraoperative TEE examination was
performed after GA induction to
observe the effects of GA put on the grade of mitral regurgitation. They
thought the reduction in MR severity was particularly pronounced when
the regurgitation was due to insufficient leaflet coaptation (annular
dilatation/ventricular dilatation),
but did not seem to decrease when
the regurgitation was due to a flail leaflet[26].
Regurgitation associated with abnormal MV structure is not significantly
influenced by GA induction[24,27,28]. Functional
MR is shown to be improved with GA when compared with its preoperative
severity[29,30]. Although the pharmacologic
simulation of hemodynamics in awake-state has been improved, the
undervaluation of MR under GA has not been completely
eliminated[24,31]. This is particularly
challenging in functional MR cases, because there may be significant
inconsistencies between the pre- and intraoperative MR severity
assessments[31,32].