Echocardiographic Evaluation of Indices of Severity of Pulmonary Stenosis in Dogs: Reproducibility and Effects of General Anesthesia.

Abstract

BACKGROUND: The effects of general anesthesia (GA) on less flow-dependent (velocity ratio, velocity time integral [VTI] ratio and indexed pulmonary valve area [iPVA]) and flow-dependent (mean [PVmeanPG] and maximum pressure gradient [PVmaxPG]) indices of severity of pulmonary stenosis (PS) are unclear. OBJECTIVES: Determine the effects of GA on indices of severity of PS in dogs undergoing an interventional procedure (IP). Determine the reproducibility of indices of severity of PS. ANIMALS: Thirty-nine dogs with PS. METHODS: Prospective cross-sectional study. Five repeated echocardiograms were performed over 3 days. Day 1: two echocardiograms were performed by 2 different operators. Day 2: echocardiograms were performed before and after GA but before IP. Day 3: an echocardiogram was performed after the IP. RESULTS: After GA, median (IQR) cardiac index (2.1 [1.6-2.6] L/min/m), PVmeanPG (45.0 [26.0-55.2] mmHg), PVmaxPG (76.6 [46.6-100.3] mmHg) were decreased (p.001) compared to before GA (2.8 [2.2-3.0] L/min/m, 55.9 [47.6-73.1] mmHg, 96.1 [81.6-127.0] mmHg, respectively). There were no differences (p.35) in velocity ratio, VTI ratio, or iPVA after GA. Intra-operator and inter-operator coefficients of variation (95% CI) were highest for iPVA (13.8% [10.4-18.4] and 13.5% [11.0-18.4], respectively) and lowest for velocity ratio (9.2% [7.7-12.3] and 9.3% [7.7-12.4], respectively). CONCLUSIONS AND CLINICAL IMPORTANCE: PVmeanPG and PVmaxPG might be misleading in states of reduced flow. An integrative assessment of severity of PS that includes less flow-dependent indices is recommended. Reproducibility of indices of severity of PS should be considered when re-evaluating dogs with PS.