P.F.F. Wijn

The uterine artery blood flow velocity waveform: reproducibility and results in normal pregnancy

Uterine artery blood flow velocity waveforms (FVW) were recorded longitudinally in normal pregnancies (n = 41) at 4-week intervals from a gestational age of 18 weeks onwards. Furthermore, reproducibility of the uterine artery FVWs and the relation with maternal heart rate (MHR) was studied. The uterine artery FVW showed a low resistance flow pattern already from 18 weeks onwards, with high diastolic flow velocity relative to systolic flow velocity. Mean values (+/- S.D.) for the Pulsatility-Index (PI) before and after 32 weeks of normal pregnancy were 0.73 (+/- 0.17) and 0.67 (+/- 0.15) respectively; for the A/B ratio these values were 1.98 (+/- 0.30) and 1.85 (+/- 0.25) respectively. Intra- and interobserver reproducibility could be established for uterine artery FVW analysis. A varying time-period between the FVWs (0-4 min), repositioning of the flow probe and different observers did not cause any systematic effect on the PI, although variation increased in case of a longer time-period between the FVWs. Overall variation of the PI in the reproducibility experiments appeared to be caused more by inter- than intrapatient variance. Inter- and intrapatient variance were in the same range for the results of the longitudinal study. A statistically significant, inverse relationship between uterine artery PI and MHR could be established in a majority of cases. The mean regression coefficient for all patients of the reproducibility study was -0.0061; PI decreases with 0.0061 when maternal heart rate increases 1 beats/min.

A comparative study of three indices of umbilical blood flow in relation to prediction of growth retardation.

The literature reporting Doppler ultrasound flow velocity waveform analysis of the umbilical artery and its applications for detecting intrauterine growth retardation (IUGR) is growing rapidly. Several indices originally introduced to evaluate different vascular beds in adults, are used to assess the vascular bed resistance downstream the umbilical artery (i.e. the placental bed). A higher resistance in this placental bed causes a decreased end-diastolic flow, which is described in combination with IUGR. The three most commonly used flow indices are: A/B ratio, Resistance Index (RI = (A-B)/A) and Pulsatility Index (PI = (A-B)/mean). In this study we evaluated which of these indices correlated best with IUGR. We calculated the three above mentioned indices from the same recordings of the blood flow (at a gestational age of 34 +/- 2 weeks) and correlated the results with the subsequent birthweight of the child. In the studied group (n = 48) 15 children were small for gestational age (SGA = less than P 10) and 33 children were appropriate for gestational age (AGA = greater than or equal to P 10). All three indices showed a significant difference in value between AGA and SGA children (see table III). The Spearman correlation-coefficients were calculated and were approximately one. So there was a high correlation between all three indices. This indicates that the different indices have the same relation to IUGR. Thus, no arguments were found to prefer one index above the other. In the second part of the study we investigated the validity of these indices to predict IUGR. The validity can be estimated from two components: the sensitivity and specificity. Both sensitivity and specificity are determined by the value of the index which discriminates between AGA and SGA. Changes in this discriminating value (the so-called cut-off point) will change both sensitivity and specificity. This last effect can be visualized in the Receiver-Operating-Characteristic (ROC) curve, which plots sensitivity against specificity for different cut-off points (see figures 4 and 5). Arbitrarily sensitivity and specificity were calculated for the cut-off points PI = 1.1 and A/B ratio = 3.0. Choosing these cut-off points, the same specificity of 87.9% with a sensitivity of 53.3% were found (table IV). It is concluded, that the sensitivity of the PI of the umbilical artery in predicting growth retardation with acceptable specificity is rather disappointing. A possible reason for this is discussed.(ABSTRACT TRUNCATED AT 400 WORDS)

EFFECT OF DISTAL OCCLUSIONS ON THE ASSESSMENT OF AORTO-ILIAC PATHOLOGY BY ANALYSIS OF DOPPLER SPECTRA

In patients with multilevel arterial obstructive disease, assessment of the severity and location of the pathology is a difficult diagnostic problem. As reported recently, the intra-arterial pressure in the common femoral artery may become normal, although aorto-iliac obstructive disease is present if the superficial femoral artery is occluded. Aorto-iliac obstructive disease can also be assessed by analysis of Doppler spectra obtained from the common femoral artery. In this study, we evaluate if this assessment of aorto-iliac obstructive disease is also harmfully affected by an occlusion in the superficial femoral artery. The results of this study demonstrate that some Doppler parameters (such as acceleration time, slope of the acceleration phase, and the resistance index), which are essential for the assessment of aorto-iliac obstructive disease, are not significantly affected by an occlusion in the superficial femoral artery. Moreover, the study shows that the status of the superficial femoral artery may also be assessed by analysis of Doppler spectra obtained from the common femoral artery.

Evaluation of renal allograft function by Doppler spectrum analysis A preliminary study

Abstract. A decreased renal function is rather common after renal transplantation. The causes of this decreased function are diverse and difficult to differentiate. Yet, duplex examination, and especially quantitative Doppler spectrum analysis of the blood velocities in the renal artery, may be an effective method for differentiating between some of these causes. Forty‐five renal transplant recipients were included in this preliminary study. Doppler spectra were recorded from the renal artery to the allograft. Parameters were derived from every Doppler spectrum in order to characterize each spectrum. Renal allograft function was evaluated on the basis of a number of clinical parameters. A significant correlation was found between the clinical parameters and the Doppler spectrum parameters indicative for changes in the peripheral resistance. Patients with a normal renal allograft function showed Doppler spectra with a high diastolic flow, typical of a vascular bed with a low peripheral resistance. Patients with a decreased renal allograft function caused by a stenosis in the renal artery could be distinguished by a low peak velocity and a low pulsatility index. A decreased allograft function caused by allograft rejection or cyclosporin nephrotoxicity also led to characteristic arterial flow disturbances. In these cases, the peripheral resistance was increased, and this was primarily reflected in a decrease in the diastolic blood velocity. We conclude that quantitative analysis of the blood velocities in the renal artery by Doppler spectrum analysis seems to be a useful, noninvasive diagnostic tool that discriminates between some of the causes of a decreased renal allograft function.

Evaluation of renal allograft function by Doppler spectrum analysis

A decreased renal function is rather common after renal transplantation. The causes of this decreased function are diverse and difficult to differentiate. Yet, duplex examination, and especially quantitative Doppler spectrum analysis of the blood velocities in the renal artery, may be an effective method for differentiating between some of these causes. Forty-five renal transplant recipients were included in this preliminary study. Doppler spectra were recorded from the renal artery to the allograft. Parameters were derived from every Doppler spectrum in order to characterize each spectrum. Renal allograft function was evaluated on the basis of a number of clinical parameters. A significant correlation was found between the clinical parameters and the Doppler spectrum parameters indicative for changes in the peripheral resistance. Patients with a normal renal allograft function showed Doppler spectra with a high diastolic flow, typical of a vascular bed with a low peripheral resistance. Patients with a decreased renal allograft function caused by a stenosis in the renal artery could be distinguished by a low peak velocity and a low pulsatility index. A decreased allograft function caused by allograft rejection or cyclosporin nephrotoxicity also led to characteristic arterial flow disturbances. In these cases, the peripheral resistance was increased, and this was primarily reflected in a decrease in the diastolic blood velocity. We conclude that quantitative analysis of the blood velocities in the renal artery by Doppler spectrum analysis seems to be a useful, noninvasive diagnostic tool that discriminates between some of the causes of a decreased renal allograft function.

Brachial artery lesions after cardiac catheterisation

In a prospective study the incidence of brachial artery injury after cardiac catheterisation and the factors involved were examined. The main aim of the study however was to determine whether immediately after the injury it was possible to predict if long-term ischaemic symptoms would occur if conservative treatment was used. Five-hundred and two patients were seen pre- and post-catheterisation. Examination included inspection, palpation, segmental blood pressure measurements before and after exercise, Doppler score evaluation and in selected cases, angiography. Twenty-nine patients (5.8%) had postcatheterisation complaints of pain, pallor, hypoaesthesia or paraesthesia. A postcatheterisation wrist blood pressure index of less than 0.85, was found in 97 patients (19%). This included 22 occlusions confirmed by angiography (4.5%). Cardiac valve disease and previous catheterisations were a risk factor. All brachial artery injuries, that is to say those patients with a postcatheterisation wrist index of less than 0.85, were treated conservatively and reviewed at 6 months. Nineteen of the 72 patients seen at follow-up still had ischaemic symptoms on effort. Postinjury complaints of pain and paraesthesia had no value in predicting whether or not ischaemic symptoms would persist, whilst angiography, wrist pulse palpation, capillary refill time and the wrist pressure index at rest had very little predictive value. The Doppler score, pallor and coldness of the hand all had some value. The best predictor of long-term ischaemic symptoms was the wrist pressure index after exercise. Brachial artery injury occurs frequently after cardiac catheterisation and ischaemic symptoms thereafter are usually mild.(ABSTRACT TRUNCATED AT 250 WORDS)

Quantitative assessment of vasospasm by Doppler spectrum analysis in patients with primary Raynaud's phenomenon

The aim of the study was to investigate whether increased peripheral resistance which is supposed to exist in patients with primary Raynauds phenomenon, can be quantified by using parameters of Doppler spectra of flow in the ulnar and radial arteries. A group of 24 patients with this abnormality were compared with a matched group of 24 normal subjects. Doppler spectra were analysed according to the methods of Fronek, Gosling and by Fast Fourier Transform analysis. The Doppler spectra obtained from patients at room temperature were very different from those in normal subjects, showing characteristic wave-forms with multiple oscillations in 92% of the patients. All three analysing techniques demonstrated significant differences between the two groups, which can be attributed to increased peripheral vascular resistance in the patient group. The results of this study emphasize the value of analysis of Doppler spectra obtained from ulnar and radial arteries in the assessment of peripheral vascular resistance in vasospastic disease.

Noninvasive Hemodynamic Assessment of Vasospasm in Patients with Primary Raynaud's Phenomenon

In order to assess vasospastic ischemic disease objectively 41 patients with primary Raynauds phenomenon and 21 normal volunteers were investigated noninvasively by digital systolic blood pressure and digital skin temperature measurements before and after instant cold provocation. Much care had been taken to be certain that all patients had primary Raynauds phenomenon. The results of digital pressure measurements appeared to be affected by interindividual variations in systemic systolic blood pressure. By introducing a digit-to-brachial systolic blood pressure index (DBI), such variations could be eliminated. Instant cold provocation did not change DBI significantly. No pressure drop due to a closing phenomenon could be observed. Both digital skin temperature and DBI differed significantly between healthy males and females. In the patient group males and females did not show significant differences. The results in healthy females were hardly different from the results in patients. Healthy males could be well discriminated from patients with both techniques. Sex differentiation appeared to be essential for the objective assessment of primary Raynauds phenomenon.

The Effectiveness of Isoxsuprine in Patients With Intermittent Claudication

Sixty male patients with intermittent claudication were investigated in a ran domized, double-blind, placebo-controlled study in order to determine the ef fectiveness of Isoxsuprine. The analysis of the results was made on the basis of subjective assessment of symptoms by the patients themselves and also on the results of segmental blood- pressure measurements and ankle/arm indices at rest and after standardised exercise. Significant differences were demonstrated between the active and placebo groups as regards pain-free walking distance although arterial pressure mea surements did not show statistically significant differences between the two groups. Isoxsuprine appears to be significantly beneficial only for patients with ob structions at the femoro-popliteal level.

The uterine artery blood flow velocity waveform in pathological pregnancy

Uterine artery blood flow velocity waveforms (FVW) were recorded longitudinally in 41 women with undisturbed pregnancy as well as in 32 women with complicated pregnancy at 4-week intervals from a gestational age of 18 weeks onwards. Of these women, four did not complete the study. In a second group of 76 patients at least one FVW was recorded after admission to the obstetrical department because of complicated pregnancy. The Pulsatility-Index (PI) for normal pregnancy was based on the results of the 41 women with undisturbed pregnancy (Mulders et al. (1988) Early Hum. Dev., 17, 55-70). The complete study group (n = 145) was divided in two groups, based on the value of the last measured uterine artery PI before delivery in the abnormal PI group (PI greater than or equal to 1.02 before 32 weeks or PI greater than or equal to 0.91 after 32 weeks, n = 38) hypertension, fetal distress during pregnancy, premature delivery, small for gestational age babies (SGA) and lower placental weight were all significantly increased. In each of the groups of patients with either SGA, fetal distress during pregnancy, pre-existing hypertension with proteinuria and pregnancy-induced hypertension with or without proteinuria the mean PI was significantly increased as compared to the results in normal pregnancy. Sensitivity and specificity of the last uterine artery PI for the detection of SGA and/or fetal distress during pregnancy were 48.8% and 82.7%, respectively. The longitudinally studied women (n = 73) were divided in two groups, based on uterine artery PI before 32 weeks of gestation; in the abnormal PI group (PI greater than or equal to 1.02, n = 12) pregnancy was more complicated by premature delivery and low birth weight. Sensitivity for the early prediction of pathological pregnancies (at least one pathological phenomenon as mentioned above) was 30.4%, whereas specificity was 90.0%.