Assessment of aortic stiffness by local and regional methods.

The stiffness of large arteries has an important role in cardiovascular hemodynamics. Aortic stiffness (AoStiff) can be assessed non-invasively with regional and local methods. In this paper, we compared these two techniques for evaluating AoStiff. Our subjects comprised of 118 consecutive patients (85 men, mean age: 49 ± 14 years). We evaluated regional AoStiff with carotid-femoral pulse wave velocity (PWV) measured with a tonometric technique and by bioelectrical impedance (BI) wave velocity (IWV). The local AoStiff was calculated from BI signals recorded at the chest. We used glyceryl trinitrate (GTN) to test the effect of peripheral vasodilatation on both methods in a subgroup of 52 patients (37 men, mean age: 52 ± 11 years). We found a significant correlation between IWV and PWV measurements (r = 0.88, P < 0.0001) as well as between AoStiff and PWV measurements (r = 0.75, P < 0.0001). GTN administration decreased mean arterial blood pressure by 4% (95% confidence interval: 2-8%, P = 0.002) without significant changes in AoStiff and regional IWV. Local AoStiff is correlated with regional measurements and is not influenced by changes in arterial pressure because of systemic peripheral vasodilatation.

Assessment of endothelial function in the radial artery using inhaled albuterol.

Endothelial dysfunction is an early indicator of developing atherosclerosis and is a strong predictor of future heart attack and stroke. At present, evaluation of endothelial function (EF) (specifically, EF mediated by nitric oxide, NO) is too technically difficult to form part of a routine clinical examination. Non-invasive methods that measure NO-dependent EF in arteries make use of a 4-5 minute blood pressure cuff occlusion of the arm in order to induce reactive hyperemia (RH) upon cuff release. The increased blood flow that results from the RH stimulates the endothelial cells to release NO and relax the surrounding vascular smooth muscle. The magnitude of the change in arterial caliber or stiffness provides a measure of EF. The cuff occlusion is uncomfortable and inflation and release inevitably move the arm, increasing the technical difficulty of obtaining reliable measurements. In beta2-adrengergic agonist albuterol induces NO-mediated vasorelaxation in resistance vessels of humans. We examine, for the first time, the effect of albuterol on conduit vessels (radial artery) by measuring changes in the transit times of artificial pulses observed after inhalation of albuterol. We conclude that albuterol is able to relax the radial artery and that this correlates with the effects of RH (r=0.62, p=0.04). However, the response to a dose of 360 micro-g is smaller and more variable when compared to the response to RH-based stimulus.

Assessment of volume preload on uteroplacental blood flow during epidural anaesthesia for Caesarean section.

BACKGROUND AND OBJECTIVE: Epidural and spinal anaesthesia are the preferred mode of anaesthesia for Caesarean section. Volume preloading is recommended to prevent maternal hypotension and a reduction in uteroplacental blood flow, although positive effects of volume preloading on maternal cardiac output and arterial pressure are debatable. Doppler measurements of the umbilical artery beyond deriving pulsatility indices are not routinely performed. METHODS: After Institutional Review Board approval and written informed consent, 14 consecutiVe women with epidural anaesthesia for Caesarean section received either hydroxyethyl starch 500 mL or gelatine 500 mL. Haemodynamic variables monitored were maternal arterial pressure, maximal blood flow velocity and pulsatility indices of the uterine artery derived from Doppler measurements. CONCLUSIONS: Maternal arterial pressure and pulsatility indices in both groups did not change from baseline after intravenous colloid infusion. However, uterine blood flow increased significantly in both groups. The effectiveness of volume preloading may therefore be better described by changes in maximum uterine blood flow velocity than by pulsatility indices or maternal arterial pressure.

Assessment of collateral perfusion: a pharmacodynamic study with buflomedil hydrochloride.

The aim of the study was to assess the influence of Buflomedil hydrochloride on collateral function. Ten patients with isolated superficial femoral occlusions were investigated twice by duplex sonography with measurement sites at the common femoral artery (CF) and the popliteal artery (PA). After the second scan 200 mg of Buflomedil hydrochloride were infused; the infusion was followed by a third duplex examination. Endpoints assessed included the arterial diameter (D(CF), D(PA)), the systolic peak velocity (Vmax), the mean velocity of the maximum envelope (Vmean m.e.), the intensity weighted time average mean velocity (Vmean i.w.), the maximum reverse flow velocity (Vrev), the end-diastolic velocity (Venddiast), the calculated volume flow (Q), the pulsatility and the resistance indices (PI, RI), and PI and RI based segmental damping factors (DF(PI), DF(RI)). For the CF measurement site the infusion of Buflomedil hydrochloride resulted in a significant reduction in Vrev and PI (p<0.05), whereas trends in the opposite direction (increase) were observed for both measures of Vmean and for Q (0.1

Comparative assessment of the effects of vasodilators on peripheral vascular reactivity in patients with systemic scleroderma and Raynaud's phenomenon: color Doppler flow imaging study.

The aim of the present study was assessment of peripheral vascular reactivity during cold test effects of different types of vasodilators on vascular resistance in patients with progressive systemic sclerosis and Raynaud's phenomenon with use of color Doppler flow imaging of upper extremity.

[Comparison of Doppler ultrasound assessment of utero-placento-fetal perfusion in normal pregnancies and in those with threatened premature labor]. / Vergleich dopplersonographisch gemessener utero-plazentofetaler Perfusion zwischen normalen Schwangerschaften und solchen mit drohender Frühgeburt.

The aim this study to compare perfusion parameters, measured by Doppler sonography, between normal pregnancies and pregnancies with symptoms of preterm labor. The patient collective comprised of 3 groups: 62 normal pregnancies (group 1), 23 preterm labor before tocolysis (group 2) and 114 preterm labor up to 48 hours under tocolysis (group 3). In each case pulsatility index was measured in the uterine artery on the placental side and non-placental side, umbilical artery, fetal descending aorta and middle cerebral artery. In the contrary to patients in group 1, patients in group 2 and 3 showed significantly elevated PI values in uterine artery placental side and non-placental side, respectively. The median of PI for both uterine arteries in both groups was significantly higher compared to that of group 1. However, 1/3 of patients with preterm labor showed pathologic uterine perfusion before or during tocolysis. The values of PI in umbilical artery, fetal descending aorta and middle cerebral artery did not reveal significant difference in all group. Nevertheless, 30% of pregnancies with preterm labor have pathological perfusion in the fetal descending aorta. We conclude that some patients with symptoms of preterm labor have pathological perfusion in uterine arteries and fetal descending aorta not induced by uterine contractions. We believe that the complex assessment of uterine perfusion should include the median PI value of both uterine arteries in order to have a reliable information. A short-term intravenous tocolysis with betamimetics does not seem to have a positive influence on the hemodynamic insufficiency.

Doppler assessment of the pulsatility index of the middle cerebral artery during constriction of the fetal ductus arteriosus after indomethacin therapy.

To investigate the effects of constriction of the ductus arteriosus on the pulsatility index of the middle cerebral artery, maximum velocity waveforms were obtained in 13 fetuses (one set of twins) whose mothers were treated with indomethacin for preterm labor (n = 9) or polyhydramnios (n = 3). Eleven of the fetuses manifested ductal constriction within 48 hours of therapy, whereas two fetuses had constriction after 1 week of therapy. Six of the 13 fetuses also manifested tricuspid insufficiency in association with constriction of the ductus arteriosus. All abnormal cardiac changes resolved in utero after discontinuation of indomethacin. No difference in the pulsatility index values of the middle cerebral artery was observed in the fetuses with ductal constriction but without tricuspid regurgitation (n = 7) when the values were compared with those obtained in absence of ductal constriction (1.87 +/- 0.37 vs. 1.88 +/- 0.33). In the fetuses that manifested both ductal constriction and tricuspid insufficiency (n = 6), the pulsatility index values in the middle cerebral artery were significantly lower in the presence of ductal constriction when compared with the values obtained in the absence of ductal constriction (2.22 +/- 0.26 vs. 1.57 +/- 0.34). These results indicate that a response to indomethacin sufficient to cause both ductal constriction and tricuspid insufficiency decreases the pulsatility index of the middle cerebral artery.