Comparison of the measured pre-ejection periods and left ventricular ejection times between echocardiography and impedance cardiography for optimizing cardiac resynchronization therapy

Abstract

Background: The pre-ejection period (PEP) and left ventricular ejection time (LVET) are easily measured by impedance cardiography (ICG). We hypothesized that the PEP/LVET measured by ICG would correlate with that measured by echocardiography, and that PEP/LVET measured by ICG would be useful for cardiac resynchronization therapy (CRT) optimization.

Methods: Newly CRT implanted patients were optimized by echocardiography. The PEP/LVET was measured by echocardiography and ICG in two different settings: optimized setting and right ventricle (RV)-only pacing.

Results: The PEP/LVET was significantly decreased in the optimized setting compared with that in RV-only pacing (0.62±0.13 vs 0.75±0.16, p<0.05). The PEP/LVET values calculated by ICG and echocardiography were positively correlated (r=0.553, p=0.003).

Conclusion: ICG was useful for the optimization of CRT.

Keywords: Cardiac resynchronization therapy; Echocardiogram; Impedance cardiography.

Fig. 1

(A) AoVTIs and PEP/LVETs measured by UCG were tended to correlate negatively (r=−0.368, p=0.059). (B) There was a positive correlation between PEP/LVETs measured by ICG and those measured by Ultrasonic Cardiography (UCG) (r=0.553, p=0.003). Data are expressed as mean±SD. *p<0.05 vs. PEP/LVETs measured by ICG. Abbreviations: AoVTI, velocity-time integral of aortic flow; ICG, impedance cardiography; LVET, left ventricular ejection time; PEP, pre-ejection period.

Fig. 2

(A) PEP/LVETs measured by impedance cardiography were decreased in the optimized setting (0.62±0.13) compared with those in RV-only pacing (0.74±0.16). The AV delay and heart rate were comparable between the optimized setting and RV-only pacing (n=27). (B) PEP/LVETs measured by echocardiogram were decreased in the optimized setting (0.60±0.1) compared with those in RV-only pacing (0.74±0.2) (n=27). Data are expressed as mean±SD. *p<0.05 vs. optimize setting. Abbreviations: AV atrio-ventricular; ICG, impedance cardiography; LVET, left ventricular ejection time; PEP, pre-ejection period; RV, right ventricle.