Two-dimensional speckle tracking for quantification of left ventricular circumferential and radial wall motion in horses

Reasons for performing study: The use of two-dimensional speckle tracking (2DST) for quantification of left ventricular (LV) function has recently been described in horses using long-axis images and short-axis images at chordal but not at papillary muscle level. Objectives: To compare the feasibility and reliability of 2DST for quantification of circumferential and radial LV function in short-axis images at papillary muscle and chordal level. Methods: Repeated echocardiographic examinations were performed on ten healthy trotter horses by two observers from a right parasternal short-axis view at papillary muscle and chordal level. Segmental and averaged peak values and timing of circumferential and radial strain and strain rate, radial displacement and rotation were measured in six LV wall segments in each imaging plane. Global peak values were calculated for circumferential strain and strain rate. The inter- and intra-observer within- and between-day variability was assessed by calculating coefficients of variation for repeated measurements. Results: 2DST analysis was feasible in each cardiac cycle although tracking was often inadequate during early diastole. Measurements of averaged systolic circumferential and radial strain and strain rate and radial displacement as well as global circumferential strain and strain rate could be determined with low variability. Early and late diastolic strain rate and systolic rotation showed a moderate variability. Radial segmental measurements were more reliable than circumferential measurements. The interventricular septum showed a higher circumferential and lower radial strain compared to the LV free wall. Peak timing was earlier at papillary muscle compared to chordal level. Conclusions: 2DST measurements of global and regional circumferential and radial LV wall motion are feasible both at papillary muscle and chordal level. Potential relevance: Several measurements showed good reliability and can be used when evaluating the technique in a clinical setting