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
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Figure 1 Flow Data by Digital Particle Image Velocimetry From the Apical Long-Axis View
The Echo freeze frames represent the divergence-free velocity vector on the scan-plane, superimposed to the reconstructed Doppler representation (A). Parametric representations of steady streaming field with superimposed velocity vectors (arrows) and the steady streaming in-plane streamlines along the divergence-free velocity field (B). The pulsatile strength field with superimposed pulsatile in-plane streamlines (C). LVOT = left ventricular outflow tract; MV = mitral valve. See Online Video 1.
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Figure 2 Description of How to Measure Quantitative Average Vortex Parameters That Represent Vortex Location and Shape
Vortex depth represents vertical position of center of vortex relative to left ventricular long axis (A, white line), and vortex transverse position represents transverse position relative to posteroseptal axis (B, white line). Vortex length was measured by longitudinal length of vortex relative to left ventricular length (C, white arrow), and vortex width was measured by horizontal length of vortex relative to left ventricular length (D, white arrow). A vortex sphericity index was calculated by vortex length and vortex width.
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Figure 3 Description of Quantitative Vortex Pulsatility Parameters
The relative strength represents strength of the pulsatile component of vorticity with respect to the average vorticity in the whole left ventricle (A, white circled area). The vortex relative strength represents the strength of the pulsatile vorticity of vortex (B, white circled area).
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Figure 4 Time Sequence Analysis of LV Flow During Ejection and IVR Period in Normal Subjects
During ejection (A to C), the direction of the contrast-vector flow was from left ventricular (LV) apex to LV outflow tract. After the aortic valve closure, in the early isovolumic relaxation (IVR) period, the direction of flow reversed from LV base to apex. During mid-late IVR period (E and F), the nonvertical columnar flow was seen directed from base to apex (early ejection: 16 ms after aortic valve opening [A]; mid-ejection: 118 ms after aortic valve opening [B]; late ejection: 245 ms after aortic valve opening [C]; IVR: 32 ms, 80 ms, and 112 ms after aortic valve closure [D to F]). See Online Video 2.
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Figure 5 Time Sequence Analysis of LV Flow During Diastole and IVC Period in Normal Subjects
In the early diastolic period (A), an irrotational flow associated with early left ventricular (LV) filling dominated the vector representation of flow. In diastasis, a relatively apically located vortex was seen (B, arrow). This was followed by a late filling phase that was characterized by an irrotational flow obscuring the vortex (C). In the early isovolumic contraction (IVC) period, the vortex was relocated in the proximity of the anterior mitral leaflet in the LVOT region (D, arrow). During the late IVC period, the vortex persisted in the left ventricular outflow tract region and directed flow towards aortic valve (E). With the aortic valve opening and ejection (F), the vortex dissipated with continued flow from apex to left ventricular outflow tract. Early diastole: 16 ms after mitral valve opening (A); diastasis: 142 ms after mitral valve opening (B); late diastole: 298 ms after mitral valve opening (C); IVC-1: 16 ms after mitral valve closure (D); IVC-2: 80 ms after mitral valve closure (E); ejection: 102 ms after mitral valve opening (F). See Online Videos 3 and 4.
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Figure 6 Time Sequence Analysis of LV Flow During 1 Cardiac Cycle in Abnormal LV Systolic Function Group
The vortex was located at the center of the LV throughout diastole and systole and did not redirect flow in a coherent, sequential fashion as in normal subjects. Early ejection: 16 ms after aortic valve opening (A); late ejection: 138 ms after aortic valve opening (B); IVR-1: 32 ms after aortic valve closure (C); IVR-2: 50 ms after aortic valve closure (D); early diastole: 32 ms after mitral valve opening (E); diastasis: 124 ms after mitral valve opening (F); late diastole: 245 ms after mitral valve opening (G); isovolumic contraction period (IVC): 64 ms after mitral valve closure (H). Abbreviations as in Figure 4. See Online Video 5.
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Figure 7 Quantitative Vortex Flow Parameters in Normal Subjects and LV Systolic Dysfunction Group
The Echo freeze frames (upper panel), and parametric representation of steady streaming field and the pulsatile strength field (lower panel) in normal (A) and left ventricular (LV) systolic dysfunction groups (B). The vortex in normal subjects showed an elliptical shape (A, Aa, white arrow, sphericity index [SI]: 2.8) and strong pulsatility (Ap, red-colored area, vortex relative strength [VRS]: 1.182), whereas spherical (B, Ba, white arrow, SI: 1.3) and weak pulsatility (Bp, blue-colored area, VRS: 0.335) vortex was observed in patients with systolic heart failure.
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Figure 8 Quantitative Flow Vortex Parameters
Comparison of morphological (A) and physiological (B) vortex parameters between normal and abnormal LV systolic function group. RS = relative strength; VD = vortex depth; VL = vortex length; VPC = vortex pulsation correlation; VW = vortex width; other abbreviations as in Figure 7.
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