Ultrasonic Measurement of Blood Flow Velocity and Applications for Cardiovascular Assessments

Bashford, Gregory R.

doi:10.1007/978-94-007-7741-5_18-1

Cited by 4 publications

(3 citation statements)

References 46 publications

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“…Echo Doppler approach By using a continuous wave Doppler (CWD) flowmeter, 8 it is possible to measure the blood speed inside the stenosis section and then calculate the pressure gradient. Since the flow is pulsatile, the mean velocity during ejection is calculated.…”

Section: Mathematical Modelmentioning

confidence: 99%

“…To measure the stenosis area, the diameter of the section of the ventricular outflow tract (D V ) is measured with echography in mid-systole and the ventricular blood speed with a pulsed wave (PW) Doppler device. 8 By applying the continuity equation ( 2), AVA can be easily calculated (6). It is important to notice that A V is hypothesised circular (7) and all the considered values are mediated along with different beats.…”

Section: Mathematical Modelmentioning

confidence: 99%

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Evaluation of low gradient severe aortic stenosis: should we change our outlook in the analysis of clinical data?

2021

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Nowadays, technological progress has equipped clinicians with new useful devices for the collection, analysis and presentation of data. As a consequence, many diseases and pathological conditions have been studied in a more detailed way, sometimes with remarkable results. In fact, they are not always validated by the old physiological models. In this respect, we present the case of low gradient severe aortic stenosis, a condition characterised by a small aortic valve area and a low-pressure gradient. According to the mathematical and physical assumptions these readings are contradictory whereas the Doppler-echocardiography shows clearly the existence of such a situation. In this work, we have described the physiological base of this phenomenon and discussed the limitations of the technology used. In this work, we are going to analyse some conditions commonly observed in daily clinical practice in order to prompt a critical outlook in both clinicians and technicians about the instrumentations used and the methods applied.

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Section: Mathematical Modelmentioning

confidence: 99%

Section: Mathematical Modelmentioning

confidence: 99%

Evaluation of low gradient severe aortic stenosis: should we change our outlook in the analysis of clinical data?

2021

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“…All three of these technologies are limited to measuring depths of only a few millimeters. Compared with light and heat, ultrasound has a higher penetration capability and causes no harm to the human body within a safe intensity (22). The ultrasound Doppler technique is the only method that can feed rapid changes in cardiovascular conditions back in real time, including the absolute mean and peak velocity of blood flow.…”

Section: Introductionmentioning

confidence: 99%

Flexible Doppler ultrasound device for the monitoring of blood flow velocity

et al. 2021

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Thrombosis and restenosis after vascular reconstruction procedures may cause complications such as stroke, but a clinical means to continuously monitor vascular conditions is lacking. Conventional ultrasound probes are rigid, particularly for postoperative patients with fragile skin. Techniques based on photoplethysmography or thermal analysis provide only relative changes in flow volume and have a shallow detection depth. Here, we introduce a flexible Doppler ultrasound device for the continuous monitoring of the absolute velocity of blood flow in deeply embedded arteries based on the Doppler effect. The device is thin (1 mm), lightweight (0.75 g), and skin conforming. When the dual-beam Doppler method is used, the influence of the Doppler angle on the velocity measurement is avoided. Experimental studies on ultrasound phantoms and human subjects demonstrate accurate measurement of the flow velocity. The wearable Doppler device has the potential to enhance the quality of care of patients after reconstruction surgery.

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Acoustic Properties of Stretchable Liquid Metal‐Elastomer Composites for Matching Layers in Wearable Ultrasonic Transducer Arrays

Krings,

Hage,

Truong

et al. 2023

Adv Funct Materials

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Ultrasound is a safe, noninvasive diagnostic technique used to measure internal structures such as tissues, organs, and arterial and venous blood flow. Skin‐mounted wearable ultrasound devices can enable long‐term continuous monitoring of patients to provide solutions to critical healthcare needs. However, stretchable ultrasound devices that are composed of ultrasonic transducers embedded in an elastomer matrix are incompatible with existing rigid acoustic matching layers, leading to reduced energy transmission and reduced imaging resolution. Here, a systematic study of soft composites with liquid metal (LM) fillers dispersed in elastomers reveals key strategies to tune the acoustic impedance of soft materials. Experiments supported by theoretical models demonstrate that the increase in acoustic impedance is primarily driven by the increase in density with negligible changes to the speed of sound through the material. By controlling the volume loading and particle size of the LM fillers, a material is created that achieves a high acoustic impedance 4.8 Mrayl, (> 440% increase over the polymer matrix) with low modulus (< 1 MPa) and high stretchability (> 100% strain). When the device is mechanically strained, a small decrease is observed in acoustic impedance (< 15%) with negligible decrease in sound transmittance and impact on attenuation for all droplet sizes. The stretchable acoustic matching layer is then integrated with a wearable ultrasound device and the ability to measure motion is demonstrated using a phantom model as is performed in Doppler ultrasound.

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Ultrasonic Measurement of Blood Flow Velocity and Applications for Cardiovascular Assessments

Cited by 4 publications

References 46 publications

Evaluation of low gradient severe aortic stenosis: should we change our outlook in the analysis of clinical data?

Evaluation of low gradient severe aortic stenosis: should we change our outlook in the analysis of clinical data?

Flexible Doppler ultrasound device for the monitoring of blood flow velocity

Acoustic Properties of Stretchable Liquid Metal‐Elastomer Composites for Matching Layers in Wearable Ultrasonic Transducer Arrays

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