2005 Fiscal Year Final Research Report Summary
Development of a method of non-invasive measurement of wave intensity, a new hemodynamic index, and its clinical application.
| Project/Area Number |
14380414
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Biomedical engineering/Biological material science
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| Research Institution | Tokyo Women's Medical University |
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Principal Investigator |
SUGAWARA Motoaki Tokyo Women's Medical University, School of Medicine, Professor, 医学部, 教授 (60010914)
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| Co-Investigator(Kenkyū-buntansha) |
NIKI Kiyomi Tokyo Women's Medical University, School of Medicine, Associate Professor, 医学部, 助教授 (40218095)
JOU Tokuka Tokyo Women's Medical University, School of Medicine, Associate, 医学部, 助手 (10343550)
UJIIE Hiroshi Tokyo Women's Medical University, School of Medicine, Associate Professor, 医学部, 助教授 (00138869)
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| Project Period (FY) |
2002 – 2005
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| Keywords | ultrasound / wave intensity / cardiac function / elasticity / color Doppler / echo tracking |
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| Research Abstract |
Wave intensity (WI) is a new index for evaluating ventriculo-arterial interactions. Wave intensity is defined as (dP/dt)(dU/dt) at any site of the circulation, where dP/dt and dU/dt are the time derivatives of blood pressure and velocity, respectively. Arterial wave intensity in normal subjects has two positive sharp peaks. The first peak occurs during early systole, the magnitude of which increases markedly with increases in cardiac contractility. The second peak, which occurs towards the end of ejection, decreases with increases in the time constant of left ventricular isovolumic relaxation. During mid-ejection between the two positive peaks of WI, negative peaks are often observed. The magnitude and the timing of these peaks give information about the strength of wave reflections and the distance between the measuring point and the position of the reflections. Although the potential usefulness of WI had been reported by several authors, there had been no on-line methods of measuring WI noninvasively. We developed an ultrasonic on-line system of measuring WI for the first time.
The system is composed of a computer, a WI unit and an Aloka ProSound SSD-6500 ultrasonic machine (Aloka, Tokyo) equipped with a combined tissue imaging (10 or 13 MHz) and Doppler (5 MHz) transducer. The WI unit receives RF echo signals and color Doppler signals from the ultrasonic machine, and calculates the change in diameter of the artery (M-mode echo tracking) and the mean blood velocity through the sampling gate (color M-mode Doppler). Since arterial pressure waveforms and diameter change waveforms are similar, a blood pressure waveform is obtained from a diameter change waveform by calibrating its peak and bottom values by systolic and diastolic blood pressure measured with a cuff-type manometer. We applied this method to the carotid artery in subjects with heart disease, and assessed ventriculo-arterial interactions quantitatively.
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