Exercise training enhances endothelial function in young men.
OBJECTIVES: The present study was designed to assess whether exercise training can enhance endothelium-dependent dilatation in healthy young men. BACKGROUND: Exercise has been shown to reduce cardiovascular morbidity and mortality, but the mechanisms for this benefit are unclear. Endothelial dysfunction is an early event in atherogenesis, and animal studies have shown that exercise training can enhance endothelial function. METHODS: We have examined the effect of a standardized, 10-week, aerobic and anaerobic exercise training program on arterial physiology in 25 healthy male military recruits, aged 17 to 24 (mean 20) years, of average fitness levels. Each subject was studied before starting, and after completing the exercise program. Baseline vascular reactivity was compared with that of 20 matched civilian controls. At each visit, the diameter of the right brachial artery was measured at rest, during reactive hyperemia (increased flow causing endothelium-dependent dilation) and after sublingual glyceryltrinitrate (GTN; an endothelium-independent dilator), using high-resolution external vascular ultrasound. RESULTS: At baseline, flow-mediated dilatation (FMD) and GTN-mediated dilatation were similar in the exercise and control groups (FMD 2.2+/-2.4% and 2.4+/-2.8%, respectively, p = 0.33; GTN 13.4+/-6.2 vs. 16.7+/-5.9, respectively, p = 0.53). In the military recruits, FMD improved from 2.2+/-2.4% to 3.9+/-2.5% (p = 0.01), with no change in the GTN-mediated dilation (13.4+/-6.2% vs. 13.9+/-5.8%, p = 0.31) following the exercise program. CONCLUSION: Exercise training enhances endothelium-dependent dilation in young men of average fitness. This may contribute to the benefit of regular exercise in preventing cardiovascular disease. (+info)
Early prenatal diagnosis of cord entanglement in monoamniotic multiple pregnancies.
OBJECTIVES: Cord entanglement is a severe complication in monoamniotic multiple pregnancies. Three cases were reviewed to determine how early ultrasound diagnosis might improve counselling and management. METHODS: In two monoamniotic twin and one dichorionic diamniotic triplet pregnancies, cord entanglement was detected between 10 and 18 gestational weeks by color Doppler and pulsed Doppler velocimetry. Pregnancies were followed up on a weekly basis with special observation of fetal behavior and use of color Doppler velocimetry. RESULTS: In Case 1, a monoamniotic twin pregnancy with cord entanglement close to the umbilical insertions was diagnosed at 10 weeks. Longitudinal follow-up showed intrauterine death of both twins at 15 weeks. In Case 2, entanglement of the umbilical cords of two monoamniotic triplets within a dichorionic diamniotic triplet pregnancy was diagnosed at 10 weeks. The pregnancy continued uneventfully until 35 weeks when cord entanglement was confirmed at Cesarean section. All triplets have since developed normally. In Case 3, monoamniotic twins were diagnosed at 18 weeks. Color Doppler detected side-by-side insertion of the umbilical cords and Doppler velocimetry suggested an entanglement at the chorionic plate. The pregnancy was complicated by polyhydramnios. Cesarean section at 36 weeks confirmed cord entanglement at the chorionic plate. Postnatal computer angiography and morphological examination of the placenta showed the presence of superficial artery-to-artery and vein-to-vein anastomoses and of deep arteriovenous shunts. The development of the twins was uneventful. CONCLUSIONS: Diagnosis of cord entanglement is feasible early in gestation. Future protocols are proposed to document the gestational age at detection, the location, and the Doppler flow patterns and to facilitate the assessment of short- and long-term development. (+info)
Resistive indices in the evaluation of infants with obstructive and nonobstructive pyelocaliectasis.
Diagnosing obstructive uropathy by renal resistive indices calculated from duplex Doppler sonographic waveforms has been supported as well as challenged in the radiology literature relating to adults. Despite reports of normally higher resistive indices in children as compared to adults, two studies have documented high sensitivity and specificity of renal Doppler sonography in the diagnosis of obstructive uropathy in children, using the same discriminatory criterion of a resistive index of 0.7 or greater as used in adults. We evaluated 43 infants with significant or bilateral pyelocaliectasis secondary to both obstructive and unobstructive uropathy and found no significant difference in the mean resistive indices or the mean difference in resistive indices of two kidneys in one patient. We conclude that Doppler sonography in infants has no value in differentiating obstructive from nonobstructive pyelocaliectasis. (+info)
Ultrasonographic arterial portography with second harmonic imaging: evaluation of hepatic parenchymal enhancement with portal venous flow.
Ultrasonographic arterial portography was evaluated with second harmonic and conventional gray scale imaging after the administration of 0.001 to 0.1 ml/kg of FS069 (Optison) in 10 dogs (four dogs with ligation of the portal vein branch) and two woodchucks with hepatocellular carcinomas. Harmonic imaging was required to obtain good liver parenchymal enhancement for ultrasonographic arterial portography to be useful. The tumors were visible as regions of greater enhancement after intravenous injection and as hypoechoic regions after superior mesenteric artery injection. The segments with portal vein ligation were not detected after intravenous injection but were clearly seen after superior mesenteric artery injection. Doppler signal measurement verified a significant difference between the portal vein and hepatic vein after superior mesenteric artery injection and in the femoral artery after intravenous versus superior mesenteric artery injection, demonstrating that minimal levels of FS069 pass through the liver. (+info)
Impaired brachial artery endothelial function is not predicted by elevated triglycerides.
OBJECTIVES: The purpose of this study was to determine if patients with modest hyperlipidemia, and no other risk factors for coronary artery disease (CAD), have impaired endothelium-dependent (ED) vasoactivity. BACKGROUND: Hypercholesterolemia impairs ED vasodilation, but the impact of elevated triglycerides on endothelial function is not as well established. METHODS: High-resolution ultrasound was used to determine flow-mediated dilation (FMD) in the brachial artery (BA) after a 5-min arterial occlusion (endothelium-dependent stimulus) and nitroglycerin-induced dilation (endothelium-independent stimulus). We studied 40 healthy controls (Group 1), 38 patients with elevated low-density lipoprotein (LDL) cholesterol (Group 2) and 35 patients with elevated triglycerides (Group 3). Patients were excluded if they had known CAD or other risk factors for CAD, or if they were receiving lipid-lowering or vasoactive medications. RESULTS: Control patients (Group 1) had normal LDL cholesterol (2.6+/-0.8 mmol/liter) and triglyceride levels (1.0+/-0.5 mmol/liter) compared with Group 2 (5.2+/-1.2 mmol/liter, 1.8+/-0.6 mmol/liter) and Group 3 (3.5+/-0.9 mmol/liter, 4.2+/-2.5 mmol/liter) subjects (p < 0.001). Baseline BA diameters were the same across the three groups. There was no significant attenuation of flow-mediated vasodilation (FMD) in either of the hyperlipidemic groups (Group 1: 10.9+/-5.0% vs. Group 2: 8.6+/-6.1% vs. Group 3: 9.4+/-3.9%; p = 0.14). However, nitroglycerin-induced vasodilation was mildly reduced (Group 1: 21.0+/-5.0% vs. 16.9+/-7.6% vs. 17.3+/-7.7%; p = 0.01). By multivariate analysis, after controlling for baseline diameters, only the ratio of LDL/high-density lipoprotein predicted a minor impairment in FMD. CONCLUSIONS: In patients free from other cardiac risk factors, modest elevations of triglycerides or LDL cholesterol do not significantly attenuate BA endothelial-dependent vasodilation. Synergism with other cardiac risk factors may be required to significantly impair endothelial function in these patients. (+info)
Fetal peripheral bronchial fluid flow during breathing movement in normal pregnancies: a preliminary study.
OBJECTIVE: To determine the fluid flow velocity waveforms in the fetal peripheral bronchus during fetal breathing movement by means of pulsed Doppler ultrasonography. DESIGN: A preliminary cross-sectional study. SUBJECTS: Twenty-eight normal pregnant women between 32 and 38 weeks of gestation. METHODS: Velocity waveforms from fetal peripheral respiratory fluid flow were acquired from the segmental bronchus (B6 or B8) which runs along the segmental artery (A6 or A8). The maximum velocity of the intrabronchial fluid flow and duration of inspiratory and expiratory phases were quantified. RESULTS: The flow velocity signal from the fluid in the fetal segmental bronchus of 17 of the 28 fetuses was detected. We observed two types of fetal breathing movement. CONCLUSION: During fetal breathing movement, the fluid in the fetal respiratory tract moves in the fetal segmental bronchus. This movement can be detected by pulsed Doppler velocimetry aided by power Doppler ultrasonography. (+info)
Comparison of alterations in fetal regional arterial vascular resistance in appropriate-for-gestational-age singleton, twin and triplet pregnancies.
The objective of this longitudinal study was to evaluate alterations in fetal vascular resistance of fetal peripheral arteries with advancing gestation in singleton appropriate-for-gestational-age (S-AGA), twin appropriate-for-gestational-age (Tw-AGA) and triplet appropriate-for-gestational-age (Tri-AGA) infants. Colour Doppler flow imaging and pulsed Doppler ultrasonographic examinations were performed on 35 S-AGA, 52 Tw-AGA and 12 Tri-AGA fetuses. The pulsatility index for middle cerebral artery (MCAPI), umbilical artery (UAPI), descending aorta (DAPI), splenic artery (SAPI), renal artery (RAPI) and femoral artery (FAPI) was measured as vascular resistance every 2 weeks after 15 weeks of menstrual age until delivery. Optimal models and normal ranges for pulsatility index for each artery in each group were generated. The alterations in various fetal regional arterial pulsatility indices with advancing gestational age showed no significant differences in S-AGA, Tw-AGA and Tri-AGA infants, respectively. These results suggest that there is no significant difference for regional arterial vascular resistance in AGA fetuses among singleton, twin, and triplet pregnancies, whereas there was a slight difference in fetal growth pattern among singleton, twin, and triplet pregnancies described in our previous investigation. (+info)
Diurnal variation in uterine artery blood flow in post-menopausal women on oestrogen hormone replacement therapy.
Doppler ultrasound was used to investigate circadian variations in uterine artery blood flow in 20 post-menopausal women in the oestrogen-only phase of combined oestrogen hormone replacement therapy with cyclical oral norethisterone or dydrogesterone. All women were examined between 0800 and 0830 h and then again between 1800 and 1830 h on the same day. Mean arterial blood pressure, heart rate and a blood sample for measurement of serum oestradiol were taken at each visit. Indices of uterine artery blood flow included the pulsatility index, resistance index, peak systolic velocity and time-averaged maximum velocity. No significant differences in the mean arterial blood pressure, pulse rate and oestradiol concentrations were detected between morning and evening visits. Significant fluctuation was observed in the pulsatility index (P < 0. 001), resistance index (P < 0.001) and time-averaged maximum velocity (P < 0.01). The assessment of uterine artery blood flow in post-menopausal women should take into account the presence of circadian variations to ensure accuracy and reproducibility of Doppler investigations. (+info)