Evaluation of changes in left ventricular myocardial function observed in canine myocardial dysfunction model using a two-dimensional tissue tracking technique

Abstract

This study was conducted to assess the ability of two-dimensional tissue tracking (2DTT) to evaluate changes in left ventricular (LV) myocardial function associated with sustained high electrical pacing. Pacemakers were implanted at the right ventricular (RV) apex of five female Beagles, and sustained high electrical pacing of 250 beats per minute (bpm) was performed for three consecutive weeks. Conventional echocardiography and 2DTT were performed at baseline, and at every week for three weeks with pacing. The baseline parameters were then compared to those of weeks 1, 2, and 3. Three weeks of pacing resulted in significant reduction of radial and circumferential global strains (p < 0.001). Regional analysis revealed reduction of segmental strains in both radial and circumferential directions, as well as increased dyssynchrony after three weeks of pacing in the radial direction (p = 0.0007). The results of this study revealed the ability of 2DTT to measure radial and circumferential strains in dogs with sustained high-electrical pacing, and allowed assessment of global and regional myocardial function and the degree of dyssynchrony.

Comparative Evaluation of Calcium-Sensitizing Agents, Pimobendan and SCH00013, on the Myocardial Function of Canine Pacing–Induced Model of Heart Failure

“…Treatment included pimobendan (Vetmedin; Nippon Boehringer Ingelheim Co., Ltd., Tokyo), and two different doses of SCH00013 (Zenyaku Kogyo Co., Ltd., Tokyo), with 5 dogs in each treatment group. Implantation of an external pacemaker lead (TF204-062; KMY Medical, Inc., Tokyo) to the right ventricular apex was performed via thoracotomy as described in a previous report, and pacing-induced HF was created by sustained high-electrical pacing of 250 bpm for 3 consecutive weeks (13). Administration of medications was initiated from the first day of pacing in the following treatment groups: pimobendan (0.25 mg/kg PO q12hrs), Low-SCH (SCH00013, 1 mg/kg PO q12hrs), and High-SCH (SCH00013, 3 mg/kg PO q12hrs).…”

Evaluation of Left Ventricular Diastolic Dysfunction with Early Systolic Dysfunction Using Two‐Dimensional Speckle Tracking Echocardiography in Canine Heart Failure Model

“…Advantages of 2DSTE include simultaneous evaluation of myocardial function independent of the angle of insonation and cardiac translational movement, and analysis of myocardial deformation in three spatial directions . Previous studies had shown that strain rate variables could be explored to assess LV diastolic dysfunction in series of cardiovascular diseases . Wang et al found that global longitudinal strain rates could predict LV filling pressures with reasonable accuracy, particularly in patients with normal ejection fraction and in those with regional dysfunction.…”

“…Sustained rapid right ventricular pacing (RVP) has frequently been applied in dogs because it can induces dilated, congestive cardiomyopathy, and severe heart failure . Therefore, in this study, we apply high‐resolution 2DSTE to investigate the sequential longitudinal and short‐axis functional changes in the canine heart failure model.…”

“…9,10 Previous studies had shown that strain rate variables could be explored to assess LV diastolic dysfunction in series of cardiovascular diseases. 2,[11][12][13][14][15] Wang et al 13 found that global longitudinal strain rates could predict LV filling pressures with reasonable accuracy, particularly in patients with normal ejection fraction and in those with regional dysfunction. Nguyen et al 14 demonstrated that patients with cardiac disease and preserved ejection fraction had diastolic abnormalities in multiple directions.…”

“…Sustained rapid right ventricular pacing (RVP) has frequently been applied in dogs because it can induces dilated, congestive cardiomyopathy, and severe heart failure. 12,[16][17][18] Therefore, in this study, we apply high-resolution 2DSTE to investigate the sequential longitudinal and shortaxis functional changes in the canine heart failure model. We determine the timing of LV diastolic dysfunction onset, identify new strain rate indices, and compare these parameters with conventional echocardiographic indices.…”