Echocardiographic assessment of cardiac function by conventional and speckle tracking echocardiography in dogs affected by patent ductus arteriosus

Background: Patent ductus arteriosus (PDA) is one of the most common congenital heart defects in dogs. Advanced echocardiographic techniques such as speckle-tracking echocardiography (STE) have not been extensively used to evaluate cardiac function in affected dogs. Hypothesis: Advanced echocardiographic techniques are more sensitive than standard echocardiographic techniques in analyzing systolic function in dogs with PDA. Animals: Forty-four client-owned dogs: 34 dogs with PDA (preoperative evaluation) and 10 healthy sex-and weight-matched controls. Methods: Prospective study. Dogs were recruited over a 2-year period. Complete echocardiographic evaluation was performed, including conventional (end-diastolic volumes indexed to body surface area in B and M-mode [EDVIB/M], end-systolic volumes indexed to body surface area in B and M-mode [ESVIB/M], allometric scaling in diastole and systole [AlloD/S], pulmonary flow to systemic flow [Qp/Qs], ejection fraction [EF] and fractional shortening [FS]) and speckle-tracking echocardiography ([STE]: global longitudinal, radial and circumferential strain [S] and strain rate [SR]). Results: Dogs with PDA had significantly different EDVIB/M, ESVIB/M, AlloD/S, Qp/Qs and all STE-derived parameters (global longitudinal S and SR, global circumferential S and SR, global radial S and SR) compared to healthy dogs. No correlation was found between standard techniques (EDVIB/M, ESVIB/M, AlloD/S, Qp/Qs) and STE-derived parameters (global longitudinal, circumferential and radial S and SR). Conclusion and Clinical Importance: Conventional parameters routinely used to assess systolic function (EF and FS) were not different between the groups; STE-derived parameters identified subtle changes in cardiac systolic function and contractility between the 2 groups of dogs. Based on these findings, STE may be a more appropriate tool to assess cardiac contractility in dogs with PDA.