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Characterization and Quantification of Vortex Flow in the Human Left Ventricle by Contrast Echocardiography Using Vector Particle Image Velocimetry

Geu-Ru Hong, MD, PhD^_*,, Gianni Pedrizzetti, PhD, Giovanni Tonti, MD, Peng Li, MD, PhD^_*, Zhao Wei, MD, PhD^_*, Jin Kyung Kim, MD, PhD^||, Abinav Baweja^||, Shizhen Liu, MD, PhD^_*, Namsik Chung, MD, PhD^¶, Helene Houle, RDCS^#, Jagat Narula, MD, PhD, FACC^||, Mani A. Vannan, MBBS, FACC^_*,_*

^_* Ohio State University, Columbus, Ohio
Yeungnam University, Daegu, Korea
University of Trieste, Trieste, Italy
Catholic University of Sacred Heart of Campobasso, Campobasso, Italy
^|| University of California, Irvine, Irvine, California
^¶ Yonsei University, Seoul, Korea
^# Siemens Medical Solutions, Mountain View, California

^_* Reprint requests and correspondence: Dr. Mani A. Vannan, Division of Cardiovascular Medicine, OSUMC, 473 West 12th Avenue, DHLRI Suite 200, Columbus, Ohio 43210 (Email: mvannan{at}osumc.edu).

Objectives: The aims of this study were to: 1) assess the feasibility of left ventricular (LV) vortex flow analysis using contrast echocardiography (CE); and 2) characterize and quantify LV vortex flow in normal subjects and patients with LV systolic dysfunction.

Background: Vortices that form during LV filling have specific geometry and anatomical locations that are critical determinants of directed blood flow during ejection. Therefore, it is clinically relevant to assess the vortex flow patterns to better understand the LV function.

Methods: Twenty-five patients (10 normal and 15 patients with abnormal LV systolic function) underwent CE with intravenous contrast agent, Definity (Bristol-Myers Squibb Medical Imaging, Inc., North Billerica, Massachusetts). The velocity vector and vorticity were estimated by particle image velocimetry. Average vortex parameters including vortex depth, transverse position, length, width, and sphericity index were measured. Vortex pulsatility parameters including relative strength, vortex relative strength, and vortex pulsation correlation were also estimated.

Results: Vortex depth and vortex length were significantly lower in the abnormal LV function group (0.443 ± 0.04 vs. 0.482 ± 0.06, p < 0.05; 0.366 ± 0.06 vs. 0.467 ± 0.05, p < 0.01, respectively). Vortex width was greater (0.209 ± 0.05 vs. 0.128 ± 0.06, p < 0.01) and sphericity index was lower (1.86 ± 0.5 vs. 3.66 ± 0.6, p < 0.001) in the abnormal LV function group. Relative strength (1.13 ± 0.4 vs. 2.10 ± 0.8, p < 0.001), vortex relative strength (0.57 ± 0.2 vs. 1.19 ± 0.5, p < 0.001), and vortex pulsation correlation (0.63 ± 0.2 vs. 1.31 ± 0.5, p < 0.001) were significantly lower in the abnormal LV function group.

Conclusions: It was feasible to quantify LV vorticity arrangement by CE using particle image velocimetry in normal subjects and those with LV systolic dysfunction, and the vorticity imaging by CE may serve as a novel approach to depict vortex, the principal quantity to assess the flow structure.

Key Words: vortex • contrast echocardiography • particle image velocimetry

Abbreviations and Acronyms   2D = two-dimensional   CE = contrast echocardiography   IVC = isovolumic contraction   IVR = isovolumic relaxation   LV = left ventricle/ventricular   LVOT = left ventricular outflow tract   MRI = magnetic resonance imaging   PIV = particle image velocimetry   ROI = region of interest   RS = relative strength   SI = sphericity index   VD = vortex depth   VL = vortex length   VPC = vortex pulsation correlation   VRS = vortex relative strength   VT = vortex transversal position   VW = vortex width