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[Doppler sonography assessment of blood flow velocity in the ascending aorta. Problems and possible solutions]
Insights
Blood flow in the aorta shows irregular patterns that vary between individuals and conditions. A new ultrasound method using an annular array transducer can measure flow more accurately across the entire vessel.
Area of Science:
- Cardiovascular physiology
- Medical imaging
- Ultrasound technology
Context:
- Transvascular blood flow distribution in the human ascending aorta is complex.
- Existing Doppler methods with single scanlines show flow irregularities.
- These irregularities vary with individual physiology, disease states (hypertrophic cardiomyopathy, aortic insufficiency), and cardiac cycle phase.
Purpose:
- To investigate the nonuniformities of transvascular blood flow distribution in the ascending aorta.
- To highlight the limitations of local Doppler measurements for determining mean velocity.
- To propose and simulate a novel ultrasound approach for comprehensive blood flow assessment.
Summary:
- Doppler measurements from 16 gates revealed significant variations in aortic blood flow velocity profiles.
- These nonuniformities underscore the inadequacy of single-point measurements for representative mean velocity.
- A computer simulation demonstrated that an annular array transducer can generate a homogeneous ultrasound beam, significantly increasing the measurement area.
Impact:
- This study emphasizes the need for holistic velocity measurements in the aorta.
- The proposed annular array transducer technique offers a potential solution for more accurate and reliable assessment of aortic blood flow.
- Improved understanding and measurement of aortic flow dynamics can aid in diagnosing and managing cardiovascular diseases.
Abstract:
Irregularities of the transvascular distribution of blood flow within the human ascending aorta have been documented by means of 16 Doppler gates positioned along one scanline of a sector scanner. The velocity profiles recorded from ten healthy adults, ten patients suffering from hypertrophic obstructive cardiomyopathy, ten patients suffering from hypertrophic nonobstructive cardiomyopathy, and ten patients with severe aortic insufficiency exhibited nonuniformities which varied not only from individual to individual but also between the groups and depending on the phase of the cardiac cycle. These variations prevent any local measurement from being representative for the instantaneous mean velocity in all cases. A reliable mean should therefore be determined by simultaneously taking into account all velocities within the vascular cross-section. A computer simulation in order to indicate a potential solution to this problem demonstrates that an annular array transducer can be excited in such a manner that it produces a homogeneous ultrasound beam of a transverse area a hundred times larger than the one obtained in the conventional maximally focussed mode.