Echocardiographic description of shunt volume in dogs with patent ductus arteriosus

Patent ductus arteriosus (PDA) can have a variable clinical course. The aims of this study were to describe Doppler estimates of shunt volume and their association with clinical and echocardiographic abnormalities.

Dogs with a diagnosis of a PDA on echocardiography were included in this study. Signalment, clinical signs, Doppler estimates of shunt volume, and outcome were collected from medical records (June 2020 and 2023) and examined for statistical associations. Groups included hemodynamically insignificant, incidental left-to-right (LR) shunt, left-to-right shunt with congestive heart failure (LCHF), and pulmonary hypertension (PH).

Most dogs had standard LR shunts (76%), 4/4 heart murmur (69%), closing Doppler pattern characterized by-continuous LR shunting and high velocity (71%), and a color flow Doppler pattern-extending to the pulmonic valve (51%). Larger left ventricular chambers and normalized color flow Doppler width (CFDw) (P=0.023) were found in clinical as compared to asymptomatic dogs. Transmitral peak E (E), left ventricular outflow tract velocities, and color flow Doppler pixilation percent fill of the main pulmonary artery (CFD%) were correlated with left chamber dimensions. The LCHF group had a larger CFDw than the LR shunt group (P=0.009), which in turn was larger than that of the PH group (P=0.004). The mean CFD% was larger in the LCHF group (P=0.008) than in the LR-shunt group.

The retrospective data collection limited standardization of image acquisition. Applicability is further limited by lack of intra-observer and interobserver variability analyses.

Doppler measures of shunt volume in dogs with PDA include E- and left ventricular outflow tract velocities, CFDw, and CFD%.