OSU Cardiology Resident The Ohio State University Columbus, OH, United States
Abstract: Background – Pulmonary vascular resistance (PVR) is an important hemodynamic variable in the development and classification of pulmonary hypertension (PH) and may aid in therapeutic decision-making. There is a lack of data on PVR in dogs with PH. Hypothesis/Objectives – Echocardiographic estimation of PVR in dogs is feasible and can be used to differentiate between pre-capillary PH (pre-PH), isolated post-capillary PH (Ipc-PH), and combined post- and pre-capillary PH (Cpc-PH) and provides valuable hemodynamic information beyond that derived from tricuspid regurgitation (TR) velocity alone. Animals – 459 dogs with PH and 38 control dogs with TR. Methods – Retrospective observational study. Eighteen clinical and 60 echocardiographic variables predicting PH and PVR were evaluated. PVR (pulmonary artery pressure divided by pulmonary flow) was calculated using 3 equations validated in people. Dogs with pre-PH, Ipc-PH, and Cpc-PH were compared using common statistical tests for large group comparisons. A p-value < 0.05 was considered significant.Results – Normal values were derived from the control dogs. There were 213 dogs with pre-PH and 246 dogs with post-PH. Average PVR was 2.4±0.8 WU, 10.2±6.2 WU, 4.3±1.1 WU, and 9.9±3.4 WU in control dogs and dogs with pre-PH, Ipc-PH, and Cpc-PH, respectively. PVR was disproportionally increased (6.6-15.4 WU) in some dogs with mild Cpc-PH (TR velocity 2.89-3.37 m/s) and normal (< 4.7 WU) in some dogs with severe Ipc-PH (TR velocity 3.95-4.72 m/s), identifying subpopulations where estimation of PVR could be particularly beneficial. Conclusions and clinical importance – Echocardiographic PVR estimation is feasible and clinically useful.
