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It has not been possible to measure wave speed in the human coronary artery, because the vessel is too short for the conventional two-point measurement technique used in the aorta. We present a new method derived from wave intensity analysis, which allows derivation of wave speed at a single point. We apply this method in the aorta and then use it to derive(More)
BACKGROUND In patients with chronic heart failure (CHF), periodic breathing (PB) predicts poor prognosis. Clinical studies have identified numerous risk factors for PB (which also includes Cheyne-Stokes respiration). Computer simulations have shown that oscillations can arise from delayed negative feedback. However, no simple general theory quantitatively(More)
Gated, pulsed, doppler ultrasound was used to study blood flow velocity profiles in the uterine vessels (arcuate arteries) during the second and third trimesters of pregnancy. A frequency index profile nomogram was constructed from 30 normal pregnancies; this demonstrated high diastolic velocity and low pulsatility. Among 31 pregnancies with complications(More)
BACKGROUND Coronary blood flow peaks in diastole when aortic blood pressure has fallen. Current models fail to completely explain this phenomenon. We present a new approach-using wave intensity analysis-to explain this phenomenon in normal subjects and to evaluate the effects of left ventricular hypertrophy (LVH). METHOD AND RESULTS We measured(More)
The results of a pilot investigation are presented. The study aimed to show that the presence of radioactive strontium-90 in human bone could be used as evidence of active uptake during life. In this way the time since death of the individual could be identified as occurring before or after the date when atmospheric levels of radioactive strontium were at a(More)
In chronic heart failure, very-low-frequency (VLF) oscillations (0.01-0.04 Hz) in heart rate and blood pressure may be related to periodic breathing, although the mechanism has not been fully characterized. Groups of ten patients with chronic heart failure and ten healthy controls performed voluntary periodic breathing with computer guidance, while(More)
Oscillations in oxygen uptake (V(O2)) and carbon dioxide production (V(CO2)) in patients with chronic heart failure differ in amplitude and phase from the oscillations in ventilation (periodic breathing, PB), leading some to doubt whether they result from PB. We applied Fourier transforms to a pulmonary gas exchange model to quantify the effects of(More)
Ultrasound imaging allows detection of pathologic change in muscle on the basis of increased strength of echoes. With current commercial equipment, however, there is no method of quantitation of the echoes representing muscle, and there is lack of uniformity in scanning methodology. We describe a specially constructed scanning system, designed to access the(More)
A linear-array pulsed Doppler duplex has been used to study third-trimester Doppler flow velocity waveforms (FVW) in the descending thoracic aorta of 98 normal and 20 severely growth-retarded fetuses. Waveforms have been normalized (frequency index profile; FIP) to remove the effect of the angle of insonation and so allow comparison at different gestational(More)
OBJECTIVES To assess the efficacy of an ultrasound scan at the first antenatal visit. DESIGN Randomised clinical trial. SETTING Women's and Children's tertiary level hospital, Adelaide, Australia. POPULATION Six hundred and forty-eight women attending for their first antenatal visit at less than 17 weeks of gestation who had no previous ultrasound(More)