Color M-mode Doppler flow propagation velocity is a preload insensitive index of left ventricular relaxation: animal and human validation
Mario J. Garcia, MD, FACCa,
Nicholas G. Smedira, MDb,
Neil L. Greenberg, PhDa,
Michael Main, MDa,
Michael S. Firstenberg, MDa,
Jill Odabashian, RDCSa and
James D. Thomas, MD, FACCa
a Department of Cardiology, Cleveland Clinic Foundation, Cleveland, Ohio, USA
b Department of Cardiothoracic Surgery, Cleveland Clinic Foundation, Cleveland, Ohio, USA
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Figure 1 Automated method of determining flow propagation velocity (vp). A color M-mode Doppler image obtained by transesophageal echocardiography is shown at the left. The value of each color pixel is decoded. The maximum velocity value obtained during early filling (E) is detected. Isovelocity lines connecting pixels that encode values of 25% (yellow line), 50% (red line), 75% (green line) and 100% (blue line) of the maximum value are displayed in the right panel. The slope of the 50% isovelocity line is then determined. See text for details.
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Figure 2 Color M-mode Doppler of left ventricular filling obtained during esmolol, at baseline and during dobutamine infusion showing the changes in E and vp. Peak E is given by the maximum color encoded velocity value during early filling (inside enclosed circle), while vp is given by the slope of the isovelocity lines (white line). E = peak early transmitral flow velocity; vp = flow propagation velocity. See text for details.
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Figure 3 Color M-mode Doppler of left ventricular filling obtained before (first image) and during caval occlusion (second and third images). Peak early filling component velocity decreases together with left ventricular end-diastolic pressure (LV-EDP), as demonstrated by the changes in pixel colors from yellow to red. In contrast the slope of the early filling wavefront which determines flow propagation velocity (vp) is unchanged. See text for details. LV-EDP = left ventricular end-diastolic pressure; vp = flow propagation velocity.
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Figure 4 Animal study: effect of preload reduction in E and color M-mode vp IVC occlusion. E = peak early transmitral flow velocity; IVC = inferior vena cava; vp = flow propagation velocity.
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Figure 5 Human study: effect of preload reduction in E and color M-mode vp during partial circulatory bypass. E = peak early transmitral flow velocity; vp = flow propagation velocity.
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Figure 6 Correlation between flow propagation velocity (vp) and the tau in the combined animal (solid circles) and human (open circles) group (trendline fitted to a power function). tau = time constant of isovolumetric relaxation; vp = flow propagation velocity. R = –0.78; y = 592.21x–0.6838; p < 0.001.
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