Background: General anesthesia (GA) alters blood flow and hemodynamics, which might impact echocardiographic estimates of maximum transpulmonary pressure gradient (maxPG). Hypothesis/
Objectives: We sought to describe intra-operator between-day reproducibility and determine the effects of GA on maxPG and less flow-dependent indices of pulmonary stenosis (PS) severity such as, velocity (Vmax) ratio, velocity time integral (VTI) ratio, and indexed pulmonary valve area (iPVA). Animals: Thirty-nine dogs with PS (maxPG >50 mmHg).
Methods: Prospective observational study. Dogs underwent two echocardiographic examinations by the same operator on different days before GA (reproducibility assessment) and after GA. Within group comparisons were made using Wilcoxon’s test. Reproducibility was quantitated using coefficients of variation (CV) and reproducibility coefficients (RC).
Results: Median (IQR) cardiac index, maxPG, and tricuspid annular plane systolic excursion were significantly (P≤0.001) decreased after GA (percent change: -14.8 [-35.8, 4.8]%, -35.3 [-49.0, -16.5]%, and -38.9 [-49.7, -18.0]%, respectively). Whereas Vmax ratio, VTI ratio, and iPVA were not significantly different (P≥0.35) after GA (0.0 [-10.9, 13.8]%, 0.0 [-10.3, 13.9]%, and -4.3 [-21.6, 12.5]%, respectively). The CVs and RCs were as follows for maxPG: 13.7%, 23.0 mmHg; Vmax ratio: 9.4%, 0.06; VTI ratio: 12.2%, 0.05; and iPVA: 14.3%, 0.12 cm2/m2. Conclusions and clinical importance: Less flow-dependent indices of PS severity (Vmax ratio, VTI ratio, and iPVA) might be more accurate under GA and in states of altered blood flow. Results support the use of an integrative assessment of PS severity. Clinicians should be mindful of the between-day variability of indices of PS severity during serial examinations.
