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Clinical and research medicine: Heart failure and left ventricular function
e0662 Evaluation of the whole and regional myocardial function of left ventricle in dogs with congestive heart failure induced by fast right ventricular pacing
  1. Zhao Ting,
  2. Wang Ke
  1. Department of Cardiology, The First Affiliated Hospital of Dalian

Abstract

Objective Use the Doppler and strain rate imaging (SRI) to evaluate the systolic and diastolic function of the whole and regional ventricular myocardial in congestive heart failure dog models induced by rapid ventricular pacing, and in order to provide more mature and sound methods and parameters to assess the clinical tachyarrhythmia left heart function.

Methods 13 healthy mongrel dogs received rapid right ventricular pacing 4 weeks at the rate of 230 beats per minute, to establish congestive heart failure models. The diastolic diameters of the left ventricle (LVDd), left ventricular end diastolic volume (LVEDV), left ventricular end systolic volume (LVESV), ejection fraction (EF), diastolic flow velocity E and A wave, E/A, and E wave deceleration time (EDT) were measured before operation and after pacing of 4 weeks. Meanwhile, the peak systolic velocities were measured by Doppler quantitative tissue velocity image at four mitral ring sites (LV septum, LV lateral wall, LV inferior wall, LV anterior wall). At SRI condition, analysis was performed in basal and mid of septal and lateral walls in the apical 4-chamber view, in basal and mid of inferior and anterior walls in the apical 2-chamber view. All the walls SRI and SR curves were obtained, and the peak strain rate in every cardiac cycle, such as peak systolic strain (PSS), and peak systolic strain rate (SRs), peak diastolic strain (PDS) were recorded.

Result 1. After 4 weeks, compared with prior pacing, the following parameters increased significantly (p<0.01): the LVDd, LVEDV, LVESV and Tei index. While LVEF of CHF dogs decreased significantly (p<0.01). 2. After 4 weeks, Compared with prior pacing, the peak systolic velocities at four mitral ring sites decreased significantly (p<0.01, or p<0.05). 3. After 4 weeks, Compared with prior pacing, the PSS and SRs in basal and mid of LV walls decreased significantly (p<0.01). While, the gradient of the PSS and SRs among the basal and mid of LV walls all disappeared (p>0.05). For example, the PSS in basal of LV walls decreased significantly (p<0.01): LV septum (5.7±5.2% vs 15.3±2.4%), LV lateral wall (7.3±1.2% vs 15.8±1.6%), LV inferior wall (4.9±3.8% vs 13.7±1.6%), LV anterior wall (6.6±0.6% vs 15.5±1.9%). The SRs in basal of LV walls decreased significantly (p<0.01): LV septum (1.0±0.4S−1 vs 2.4±0.6 S−1), LV lateral wall (1.3±0.5 S−1 vs 2.3±0.5 S−1), LV inferior wall (1.0±0.3 S−1 vs 1.8±0.4 S−1), LV anterior wall (1.4±0.4 S−1 vs 2.6±0.7 S−1). 4. Compared with prior pacing, peak velocities of E and A waves, E/A and EDT showed no difference (p>0.05). However, the PDS in basal and mid of LV walls decreased significantly (p<0.01). While, the gradient of the PDS among the basal and mid of LV walls all disappeared (p>0.05). For example, the PDS in basal of LV walls decreased significantly (p<0.01): LV septum (7.1±1.2% vs 15.6±2.7%), LV lateral wall (7.5±1.1% vs 14.9±1.7%), LV inferior wall (6.6±1.5% vs 13.6±1.8%), LV anterior wall (6.5±1.0% vs 15.5±2.3%).

Conclusion After rapid ventricular pacing, congestive heart failure occurred in these experimental dogs, not only did the whole and regional myocardial systolic function decreased significantly, but also did to some extent the ventricle diastolic function changed. SR and SRI can be used to evaluate systolic and diastolic regional myocardial function in CHF dog models induced by rapid ventricular pacing and may provide more mature and sound parameters to assess the left heart function.

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