Peak systolic velocity and flow volume increase with blood pressure in low resistance systems.

Abstract

This study demonstrates that when vascular resistance is low, peak systolic velocity and peak flow volume increase with increasing blood pressure. We used ischemia with reactive hyperemia to create reproducible low resistance conditions in 32 volunteers. Ischemia resulted in sharp increases in systolic and diastolic velocities, while the difference between these velocities increased minimally. Spontaneous variations in subject's systolic blood pressure were positively correlated with peak sys-R ecent reports have shown excellent results in distinguishing malignant from benign ovarian masses by high Doppler shift frequencies and low Doppler index values (RI, PI).t· 3 In other studies, malignant and benign lesions have shown overlap of these measurements.4. . . ' 5 We speculated that systemic BP might be an uncontrolled variable in study populations, accounting for some of the observed inconsistency. To evaluate the potential effect of BP, we used a low resistance is- We conclude that low resistance flow is blood pressure dependent. Because blood pressure increases with age, tumor velocity and frequency shift thresholds may need blood pressure correction if applied over wide age ranges. The resistive index was independent of blood pressure and thus may be preferable. KEY WORDS: Doppler ultrasonography; Blood flow; Blood pressure; Neoplasm. chemic model in normal volunteers to simulate low resistance tumor flow. Under these conditions, we characterized the relationship between spontaneous variations in systemic BP found among our subjects and the corresponding variations in Doppler sonographic measurements of velocity, flow volume, and Rl. SUBJECTS AND METHODSWe studied 32 volunteers (21 male and 11 female) between the ages of 24 and 53 years. None had a history of heart disease, anemia, or use of vasoactive drugs.The subjects were examined while resting supine. The systemic BP was estimated by auscultation of systolic and diastolic Korotkoff's sounds in the brachial artery below a blood pressure cuff on the right upper arm.For the study of Doppler flow during reactive hyperemia, the BP cuff was placed on "the upper right forearm of the subject. A transverse gray scale sonographic image 10 em above the elbow was used to

Evaluation of quantified contrast-enhanced color and power Doppler ultrasonography for the assessment of vascularity and perfusion of naturally occurring tumors in dogs

“…35 A correlation between the Doppler power and Hct was deter-mined in another study. 37, 38 In the dogs in our study, systemic blood pressure was not evaluated prior to Doppler ultrasonographic examination. In some dogs included in the present study, RBC count, Hct, and hemoglobin concentration were at the lower limit of the reference range or even mildly decreased, but significant associations of these variables with MCL, FA, or CWFA of pre-and postcontrast power Doppler ultrasonography were not identified.…”

Evidence for the autoregulation of vesical circulation by intravesical potassium chloride and distension in the normal human bladder

“…In flaccid conditions, the bladder wall arteries have a spiral form [1,2] and it can be assumed that the stretching of the coiled arteries upon distension of the bladder wall, and possible vasoconstriction, accelerate blood circulation purely mechanically. In this context, the investigations of Terry et al [13,14] are particularly relevant; they showed that at least in vessels with low resistance, if there is no change in RI, a rise in PSBFV also represents a rise in the blood flow rate. The flow spectra deduced from the bladder wall vessels showed evidence of low resistance.…”

Interpretation of Doppler signals

“…First of all, the conversion between Doppler shift frequency and velocity requires an accurate Doppler angle correction, which can be hazardous in curved stenotic vessels. Secondly, frequency shifts and velocities may vary with blood pressure [13]. Thirdly, the use of short pulse duration and/or wide Doppler aperture with linear array probes may induce a so-called intrinsic spectral broadening responsible for inaccurate calculations [4,14]; therefore, care and prudence are required in clinical practice [4].…”