B6: Cardiovascular Mechanics II

QUANTITATIVE ANALYSIS OF INTRAVENTRICULAR FLOW DYNAMICS IN PATIENTS WITH ISCHEMIC HEART DISEASE

Bee Ting Chan1, Hak Koon Yeoh1, Yih Miin Liew1, Yang Faridah Abdul Aziz1,2, Kok Han Chee1,2, Ganiga Srinivasaiah Sridhar1,2, Zhen-Vin Lee2, Einly Lim1

1University of Malaya, Malaysia;
2University of Malaya Medical Centre

This study aims to investigate the intraventricular flow dynamics in ischemic heart disease (IHD) patients with varying degrees of left ventricular ejection fraction (LVEF). We recruited 47 subjects, including 20 healthy volunteers, 11 IHD patients with preserved LVEF (PPEF) and 16 IHD patients with reduced LVEF (PREF). Phase contrast magnetic resonance imaging (MRI) was used to assess flow energetic indices, which include energy dissipation, kinetic energy fluctuation (E’) and vorticity fluctuation. Meanwhile, vortex flow parameters including vortex area, vortex circulation, vortex sphericity, vortex Reynolds number and vortex kinetic energy (KE) were also evaluated. The relationship between these flow variables and left ventricular function (indicated by LVEF) was investigated. LVEF was calculated from motion corrected 3D geometrical models reconstructed based on short axis and long axis cine MR images. Speckle tracking echocardiography was performed to evaluate global longitudinal myocardial strain (GLS) as well as the standard deviation of time-topeak systolic strain (time SD) which indicates left ventricular dyssynchrony. Our results showed that while E’ and vortex KE were significantly lower in PREF as compared to both healthy volunteers and PPEF, they have a substantially larger vortex area. One notable finding in this study is that while analyzing E’ within and outside of the vortex core region, both healthy volunteers (0.77±0.08 vs. 0.65±0.07, p<0.001) and PPEF (0.76±0.12 vs. 0.64±0.06, p<0.05) demonstrated a significantly higher E’ within the vortex core region, but opposite phenomena was observed in PREF. Using linear correlation analysis, LVEF showed a positive correlation with E’ (r=0.67, p<0.001), vortex KE (r=0.65, p<0.001) and GLS (r=0.54, p<0.005) in IHD patients. However, we found no association between time SD and flow energetic indices. The present study indicates that both E’ and vortex KE play significant roles in sustaining left ventricular function in IHD patients.

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