Speckle-Tracking Echocardiography in Dogs With Patent Ductus Arteriosus: Effect of Percutaneous Closure on Cardiac Mechanics

Abstract

Background: Patent ductus arteriosus (PDA) is 1 of the most common congenital heart defects in dogs and percutaneous closure is effective in achieving ductal closure; PDA closure is associated with abrupt hemodynamic changes.

Hypothesis: A marked decrease in standard parameters of systolic function as assessed by M- or B-mode echocardiography after PDA closure was identified in previous studies. Speckle tracking echocardiography can provide further insight into the effect of PDA closure on cardiac mechanics in dogs affected by PDA.

Animals: Twenty-five client-owned dogs with PDA.

Methods: Prospective study. Dogs were recruited over a 2-year period. Complete echocardiographic evaluation was performed before and 24 hours after PDA closure, including standard (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 [AlloD] and systole [AlloS], pulmonary flow to systemic flow [Qs/Qp], ejection fraction [EF], and fractional shortening [FS]), and advanced speckle-tracking echocardiography (STE): global longitudinal, radial, circumferential and transverse strain (S), and strain rate (SR).

Results: Patent ductus arteriosus closure was associated with statistically significant decreases in EDVIM /B and ESVIM /B , AlloD and AlloS, SI, EF, and FS. A statistically significant decrease in the absolute values of radial, transverse, and circumferential S and SR was observed, whereas longitudinal S and SR did not change significantly.

Conclusion and clinical importance: Patent ductus arteriosus closure by percutaneous approach is associated with marked decreases of conventional echocardiographic parameters as a result of the changes in loading conditions, but no evidence of systolic dysfunction was identified by means of STE, as none of the S and SR values were below reference ranges. In the short term, contractility is enhanced in the long axis (long S/SR values were not statistically different before and after closure) and decreases to normal values in short axis (circumferential, radial, and transversal S/SR decreased to normal reference range).

Keywords: Congenital heart disease; Dogs; Strain; Strain rate.

Figure 1

Tracking sequence. The starting points for endocardial tracing (B) are manually placed (2 at mid plane), then the software provided tracking guidance by the presence of drawn lines originating from the LV cavity where the endocardial border had to be manually identified and selected (C & D, a total of 12 points in short axis views). After selecting these points, the software automatically divides the myocardium into segments (E), as shown by a continuous line traced, which should follow the endocardial border and is manually adjusted to fit. Velocity vector imaging (VVI) arrows are then displayed above the endocardial border and help evaluating tracking quality during the cardiac cycle : the direction of the arrows indicates the direction of the movement of the left ventricular myocardium and the length of the arrow indicates the velocity of such movement (F).

Figure 2

Examples of the graphs originating with STE software. On top, circumferential S and SR, longitudinal S and SR, transversal S and SR, radial S and SR.