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Flow patterns in the dilated ischemic left ventricle studied by MR imaging with velocity vector mapping
1Magnetic Resonance Unit, Royal Brompton Hospital National Heart and Lung Institute, London, United Kingdom.
Insights
Magnetic resonance velocity vector mapping reveals distinct left ventricular flow patterns in dilated hearts compared to healthy ones. This technique accurately visualizes blood flow dynamics, aiding in understanding heart conditions.
Area of Science:
- Cardiovascular Imaging
- Biomedical Engineering
- Fluid Dynamics
Background:
- Dilated left ventricles, often due to coronary artery disease, exhibit altered blood flow dynamics.
- Understanding these flow patterns is crucial for diagnosing and managing heart conditions.
Purpose of the Study:
- To investigate and compare left ventricular (LV) blood flow patterns in patients with dilated LV and healthy volunteers.
- To evaluate the efficacy of magnetic resonance velocity vector mapping (MRVV) in characterizing these flow differences.
Main Methods:
- Utilized magnetic resonance velocity vector mapping (MRVV) to acquire cine gradient echo images in the LV.
- Simultaneously encoded vertical and horizontal velocity components, processing them into velocity vector maps.
- Studied 11 patients with dilated LV (age 57 +/- 12) and 10 healthy controls (age 50 +/- 9).
Main Results:
- Significant differences observed in heart rate, end-diastolic volume, ejection fraction, and inflow stream diameter between groups.
- Healthy subjects showed diastolic flow towards the apex with small vortices.
- Dilated LV patients exhibited inflow directed towards the free wall, creating a persistent circular flow pattern throughout diastole.
Conclusions:
- Magnetic resonance velocity vector mapping is a highly effective tool for studying intricate left ventricular flow patterns.
- MRVV can differentiate between normal and abnormal LV hemodynamics, offering valuable clinical insights.
Abstract:
Magnetic resonance velocity vector mapping was used to study flow patterns in dilated and healthy left ventricles. Eleven patients (age mean +/- SD, 57 +/- 12 years) with dilated left ventricle resulting from coronary artery disease and 10 healthy volunteers (age 50 +/- 9) were studied. Cine gradient echo images were acquired in the left ventricle vertical and horizontal long axes. Vertical and horizontal velocity components in the horizontal long axis plane of the left ventricle were encoded simultaneously. Maps of velocity components were then processed into multiple computer generated streaks whose orientation and length corresponded to velocity vectors. The following parameters (mean +/- SD) differed significantly between the two groups: The heart rate (patients 70 +/- 11 beat/min. controls 57 +/- 8, P < .001), end-diastolic volume (patients 264 +/- 83 ml, controls 143 +/- 25 ml, P < .001), ejection fraction (patients 31% +/- 7, controls 61% +/- 5, P < .001), diameter of the inflow stream (patients 1.7 +/- 0.6 cm, controls 3.2 +/- 0.3 cm, P < .001). In normal subjects the predominant direction of diastolic flow through the mitral valve was toward the apex, with short-lived vortices curling back behind each mitral leaflet. The vortex beneath the anterior leaflet tended to be larger and more dominant. In patients with dilated left ventricle, the inflow was directed toward the free wall, giving rise to a well developed circular flow pattern turning back toward the septum and outflow tract and persisting through diastole. Magnetic resonance velocity vector mapping is an excellent method for studying left ventricular flow patterns.(ABSTRACT TRUNCATED AT 250 WORDS)