LETTER TO THE EDITOR
Color M-mode Doppler flow propagation velocity in cardiac tamponade: Reply
Mario J. Garcia, MD, FACCa
a The Cleveland Clinic Foundation, Section of Cardiovascular Imaging, Department of Cardiology/F15, Cleveland, Ohio 44195, USA
garciam{at}cesmtp.ccf.org
The recent implementation of new Doppler echocardiographic methods for the assessment of diastolic function has improved our understanding of this complex entity. Standard indices of transmitral flow are hampered by their dependency on loading conditions and left ventricular (LV) relaxation and have therefore been unable to differentiate a patient with normal (normal relaxation and preload) versus pseudonormal (impaired relaxation and increased preload) LV filling (1). More recently, the velocity of flow propagation into the LV (Vp) has been shown to provide an estimate of LV relaxation (2,3). Takatsuji et al. (4) studied a large group of patients with normal relaxation, delayed relaxation and pseudonormal pulsed Doppler patterns of LV filling confirmed by hemodynamic findings. While pulsed Doppler indices showed the typical "U-shaped" distribution from normal to delayed relaxation in pseudonormal patients, color M-mode Doppler Vp was equally low between the last two groups. Furthermore, their study also showed a strong negative correlation between  and Vp, despite a wide variability in LV filling pressures among the three groups of patients, suggesting that Vp was less influenced by preload. In a study published in the January 2000 issue of the Journal (5), we demonstrated in controlled experimental settings that Vp was not affected by preload reductions in dogs undergoing caval occlusion and humans during partial bypass.
The letter of Togni et al., describing the changes in color M-mode flow propagation velocity (Vp observed in a patient with cardiac tamponade, is of significant interest. The authors demonstrate 1) significant respiratory variability of Vp during cardiac tamponade, increasing during inspiration and 2) a significant decrease in Vp after pericardiocentesis. A possible explanation for the respiratory variability observed may be periodic misalignment between the direction of flow and the M-mode cursor, changing the Doppler angle of incidence. This is likely to occur in the presence of a large pericardial effusion, when increased inspiratory venous return to the right heart can result in lateral translation of the LV. We agree with the authors, who conclude that the overall higher Vp during tamponade is likely due to a catecholamine-driven increase in LV relaxation. The fact that Vp decreased after pericardiocentesis, when venous return to the LV should increase, further supports that Vp is a preload-insensitive index.
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References
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- Garcia MJ, Thomas JD, Klein AL. New Doppler echocardiographic applications for the study of diastolic function. J Am Coll Cardiol. 1998;32:865–875[Abstract/Free Full Text]
- Brun P, Tribouilloy C, Duval AM, et al. Left ventricular flow propagation during early filling is related to wall relaxation: a color M-mode Doppler analysis. J Am Coll Cardiol. 1992;20:420–432[Abstract]
- Stugaard M, Risoe C, Ihlen H, Smiseth OA. Intracavitary filling pattern in the failing left ventricle assessed by color M-mode Doppler echocardiography. J Am Coll Cardiol. 1994;24:663–670[Abstract]
- Takatsuji H, Mikami T, Urasawa K, et al. A new approach for evaluation of left ventricular diastolic function: spatial and temporal analysis of left ventricular filling flow propagation by color M-mode Doppler echocardiography. J Am Coll Cardiol. 1996;27:365–371[Abstract]
- Garcia MJ, Smedira NG, Greenberg NL, et al. Color M-mode Doppler flow propagation is a preload insensitive index of left ventricular relaxation: animal and human validation. J Am Coll Cardiol. 2000;35:201–208[Abstract/Free Full Text]
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