Relationship of myocardial mechanics and regional volume change in patients with left ventricular systolic dysfunction
The contraction and rotation of left ventricular (LV) segments in a synchronous fashion is vital for cardiac pump function. However, no data exist regarding the relationship of LV segmental mechanics and regional volume change in patients with LV systolic dysfunction. Thirty-two patients with EF < 50% and fifty-two normal subjects were enrolled. The radius strain and rotation were assessed in six segments at three short axis views using speckle tracking imaging. The mean and standard deviation (SD) of the strain peak time index (SPTI%) and the rotation peak time index (RPTI%) for each view were calculated as representing myocardial segmental synchrony. The mean and the SD of the 4-D mini-volume time index (VMTI, %) from 16 regions were calculated as representing regional volume change using real-time three-dimensional echocardiography (RT-3DE). The SD for each time index was averaged as the systolic dyssynchrony index (SDI) in both groups. The differences of the SPTI and the RPTI to the VMTI (Tsv and Trv) were calculated as dyssynchrony between myocardial segmental mechanics and regional volume change. The time interval of the RPTI between apical and basal rotation (Tabrot) was also calculated. The relationship of Tsv, Trv and Tabrot to LV ejection fraction (EF) was then analyzed. In patients with LV systolic dysfunction, both peak strain and peak rotation occurred later than the regional minimum volume (55.3 ± 11.1% vs. 45.9 + 5.5%; 50.4 ± 8.7% vs. 45.9 ± 5.5% (both P < 0.05) as compared with normal subjects (41.1 ± 6.6% vs. 40.3 ± 3.8%; 44.1 ± 7.5% vs. 40.3 ± 3.8%). The SDI in each time index is also significantly wider than in normal subjects (P < 0.001). In addition, there was a negative correlation between Tsv, Trv and Tabrot with EF, respectively (P < 0.05). In patients with abnormal LV systolic function the rotation occurs significantly later than regional volume change as compared with normal subjects. There is a negative correlation between this time delay and LVEF. Thus, the relationship of myocardial segmental change and regional volume change could provide insight into intraventricular dyssynchrony in patients with LV systolic dysfunction.
KeywordsMechanical Hemodynamic Dyssynchrony Systolic function
We appreciate the technical assistance of Timothy Brown RDCS and Debra Wynne RDCS, as well the editorial support of Ms. Kathleen Yates.
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