Echocardiographic Pulmonary to Left Atrial Ratio in Dogs (ePLAR): A Differential Marker of Pre- and Postcapillary Pulmonary Hypertension

Pulmonary Hypertension (PH) in dogs is a complicated syndrome that could be primary, due to idiopathic or genetic causes, or secondary due to pulmonary disease, pulmonary thromboembolism, heartworm disease, heart failure. Due to the inability of the routine use of right heart catheterization in veterinary patients, there is a lack of differential criteria between PH forms. This study was performed to verify ePLAR as a differential marker in PH forms. Analyze wide specter of echocardiography-derived markers and novel ePLAR-marker to find efficient parameters in PH differentiation and ePLAR accuracy. We studied 59 dogs of different sex, age and breed. Groups were formed according to a primary pathology: Healthy dogs (HD, n = 8); dogs with MMVD and postcapillary PH (PostPH, n = 23); dogs with MMVD and precapillary PH (PrePH, n = 28). Animals in the study were diagnosed with the primary disease by standard echocardiographic methods and algorithms. In Post PH, LA was significantly larger than in the PrePH and the control. Left vertical walls were thicker in the PrePH than in the PostPH. Left ventricle diameter was higher in the PostPH than in the control and the Pre-PH. PV was smaller in the PrePH than in the Post PH and the control (р<0.001 and р<0.021). PV/RPA in the PrePH was lower than in the control and in the PostPH (р<0.001). AT was lower in the PrePH and the PostPH. AT/ET ratio was higher in the control to both experimental. AT/ET was lower in the PrePH to the PostPH. RV was dilated both in the PrePH and the PostPH to control. RV wall thickness was increased in the PrePH in comparison to both control and PostPH. Significant reductionin E-wave velocity for both the PrePH and PostPH to control and PostPH; reduction in A-wave; decreased Е/А. TR velocity was higher in both experimental to control, but didn't differ between each other. ePLAR increased in the PrePH and PostPH to control. In this study we found several echocardiographic parameters to differentiate Pre-and Post-PH forms: LA, LA/Ao, LV diameter, LV/RPA, IVS thickness and a novel in veterinary studies index - EPLAR.