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Keywords:

  • cardiac imaging;
  • Doppler echocardiography

Abstract

  1. Top of page
  2. Abstract
  3. Discussion
  4. References
  5. Supporting Information

We describe the use of vector flow mapping (VFM), a novel echocardiographic technique allowing intracardiac flow visualization, to quantify flow intensity inside a left ventricular aneurysm in a 68-year-old man. VFM successfully identified areas of stagnant flow corresponding to the wall region where a thrombus had been formed.

A 68-year-old male with prior myocardial infarction involving anterior, septal, and inferior walls underwent conventional echocardiographic evaluation complemented with vector flow mapping (VFM), a novel echocardiographic technique allowing intracardiac flow visualization and quantification.

Two-dimensional transthoracic echocardiogram showed an aneurysm at the anterior and inferior-apical segments with a 1.5 cm. wide thrombus attached to its inferior wall, with no thrombus at its apical and anterior walls. VFM allowed visualization of the direction of blood flow inside the aneurysm displayed as yellow arrows, (Figs. 1 and 2; movie clip S1) as well as a detailed measurement of its regional intensity in 3 analysed segments of equal size intersecting the aneurysm wall in areas with thrombus.

image

Figure 1. Flow velocity inside the aneurysm is quantified at selected frames, representative of its motion during diastole (Panels D1–D3) and systole (S1–S3). B. The graph on the left-side displays flow intensity across the selected regions of the aneurysm throughout the cardiac cycle, showing significant differences between the region free of thrombus (blue curve) and those where thrombus is observed (A., yellow mark) (yellow and pink curves), in which flow velocity is extremely low through most of the cardiac cycle.

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image

Figure 2. Blood flow quantification shows the distal area inside the aneurysm where flow intensity is extremely low. Blood residing close to the inferior wall of the aneurysm, where thrombus is observed (arrow), experiences no motion and presents very low or nonexistent flow velocities throughout most of the cardiac cycle, as observed in AC.

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Flow inside the aneurysm increases during early contraction and progressively decreases during mid- and late-systole. When diastolic inflow reaches the apical area, it enters the aneurysm and generates an anticlockwise vortical flow, preventing blood stagnation in the anterior-apical region during diastole and intensifying after atrial contraction. Blood residing close to the inferior wall of the aneurysm, where thrombus is observed, does not increase during these phases and presents very low or nonexistent flow velocities throughout most of the cardiac cycle.

Discussion

  1. Top of page
  2. Abstract
  3. Discussion
  4. References
  5. Supporting Information

Recently developed imaging techniques are able to map the distribution of flow velocities inside cardiac chambers.[1] One of these techniques, VFM, obtains flow velocity data in all directions through the integration of 2 data sources: color Doppler and wall-motion tracking. This allows a reconstruction of flow motion inside cardiac chambers, hence creating the possibility to analyse flow across selected areas solving the angle-dependency limitation of color Doppler alone. This technique has been reported to be a useful tool to study complex flow structures inside cardiac chambers.[2] The possibility to quantify intracardiac flow velocity can be of particular interest in selected regions where blood may stagnate or present very low velocities, increasing risk of thrombus formation. Conventional Doppler-based measurements do not reliably quantify real blood motion in all directions of the visualized plane due to angle-dependency. This limitation is particularly relevant when analysed regions contain flow moving predominantly in directions perpendicular to the ultrasound beam.

The application of new techniques, such as VFM, may be of use to study intracardiac regional flow dynamics in areas at risk of presenting blood stagnation to identify areas with higher probability of developing thrombi.

References

  1. Top of page
  2. Abstract
  3. Discussion
  4. References
  5. Supporting Information

Supporting Information

  1. Top of page
  2. Abstract
  3. Discussion
  4. References
  5. Supporting Information
FilenameFormatSizeDescription
echo12380-sup-0001-movieclip1.avivideo/avi46203KMovie clip S1 for Figure 1.

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