Biomedical subjects

K van der Mooren

Publications and source records attributed to K van der Mooren.

10 recordsLinked to original sources

PubMed1996

Bisferiens peaks in the radial artery pressure wave during patent ductus arteriosus in newborn infants: relationship with ascending aortic flow.

Previously, we found evidence that bisferiens peaks in the radial artery pressure wave in the newborn infant may suggest the presence of a left-to-right shunt through a patent ductus arteriosus (PDA). The purpose of the present study was to analyze the origin of this pulsus bisferiens. Starting from the assumption that the radial artery pressure wave form is similar to the aortic pressure wave form, as described previously, we attempted to explain the bisferiens peaks on the basis of echocardiographically obtained ascending aortic flow. We studied 11 preterm mechanically ventilated infants with a left-to-right shunt through a PDA and 7 without. Aortic volume flow was established echocardiographically, and radial artery blood pressure measurement was performed with a high fidelity cathetermanometer system. Ascending aortic peak flow during PDA was significantly higher in the case of PDA, compared with the case without PDA. An augmented peak flow with an abrupt decline after the high peak in PDA, resulting in a sharp pressure peak with a steep decline after the peak, was thought to explain the first sharp peak of pulsus bisferiens. An abrupt decline of flow after peak flow is thought to be due to the fast runoff of blood through the ductus. According to the pulsatile pressure dynamics theories, which state that pressure wave forms consist of forward and backward wave forms, the second peak of the pulsus bisferiens can be explained by the return of the reflected (backward) wave form when the forward wave form has already considerably decreased. We conclude that the bisferiens peaks found in PDA result from a combination of large stroke volume (augmented first peak) and large runoff (quick decline of the forward wave) before the return of the reflected wave.

Aorta↗

PubMed1992

Fetal atrioventricular and outflow tract flow velocity waveforms during conducted and blocked supraventricular extrasystoles.

Maximum flow velocity waveforms at atrioventricular and outflow tract level were studied cross-sectionally in 19 human fetuses with conducted and/or blocked supraventricular extrasystoles ranging from 25 to 38 weeks of gestation. At outflow tract level, peak systolic velocity and acceleration time for extrasystolic and post-extrasystolic beats were compared with those for the immediately preceding normal beat. Regression lines were calculated for peak systolic velocities with filling time. At atrioventricular level, peak-E wave and peak-A wave velocities and E/A ratio for the extrasystolic and post-extrasystolic beats were compared with those for the normal beat. At all levels, time-averaged velocities were compared with reference charts standardized for gestational age.Peak systolic velocity and acceleration time during the post-extrasystolic beat were higher than during the normal beat; the Frank-Starling mechanism, post-extrasystolic potentiation as well as reduced ventricular afterload may all play a role in this. At all measuring levels, time-averaged velocity during the extrasystolic beat was strikingly lower than the reference velocities. It is postulated that the increased blood volume and contraction force during the post-extrasystolic beat cause the valve area to become larger, resulting in a relative decrease in velocities measured by Doppler ultrasound.

Journal Article↗

PubMed1992

Reproducibility of fetal cardiac flow velocity waveforms at atrioventricular level.

Reproducibility of flow velocity waveform recording and analysis was studied at fetal atrioventricular level (mitral and tricuspid valve) in 25 normal pregnancies. The flow velocity parameters studied were peak-E wave velocity, peak-A wave velocity and time-averaged velocity. In each patient, two consecutive measurements were performed (time delay, 15 min) and of each measurement two hardcopies were analyzed. A high reproducibility was achieved for all parameters studied; the coefficients of variation between readings of hardcopies were < or = 2% and the coefficients of variation between tests within patients were < or = 4%.

Adult↗

PubMed1991

Fetal atrioventricular and outflow tract flow velocity waveforms during normal second half of pregnancy.

Maximum flow velocity waveforms at atrioventricular and outflow tract level were studied longitudinally in 40 fetuses from 18 to 38 weeks' gestation at 3- to 4-week intervals. Flow velocity parameters studied were peak systolic and time-averaged velocity and acceleration time at outflow tract level and time-averaged velocity, peak E-wave and peak A-wave velocities, and E/A ratio at atrioventricular level. An increase of all flow parameters with advancing gestational age was found. Aortic parameters were higher than pulmonary ones. Time-averaged, peak E-wave, and peak A-wave velocities were higher at tricuspid level than at mitral level, whereas E/A ratios were higher at mitral level. Outflow tract parameters showed no correlation with period time. A positive correlation for peak E-wave velocity and E/A ratio, and a negative correlation for time-averaged and peak A-wave velocity was found with period time. These results suggest that the normal second half of pregnancy is characterized by rising ventricular stroke volume and output and reduction in ventricular afterload. The left ventricular afterload seems to be lower than the right ventricular afterload. Atrioventricular flow velocities are heart rate dependent.

Blood Flow Velocity↗

PubMed1991

Effect of fetal breathing movements on fetal cardiac hemodynamics.

Maximum flow velocity waveforms were studied at atrioventricular and outflow tract level in 12 cases during fetal breathing activity and in 12 cases during fetal apnea matched for maternal and gestational age and maternal parity. Gestational age ranged between 27 and 40 weeks (median 30 weeks). All flow velocity waveforms were obtained using a mechanical sector scanner with a pulsed Doppler system (carrier frequency 3.5 MHz). Time-averaged flow velocities were clearly different between inspiration and expiration at all four recording levels, reflecting changes in venous return as a result of fluctuations in intrathoracic pressure during fetal breathing activity. Percentage change between inspiration and expiration at outflow tract level was positively correlated with gestational age. Time-averaged flow velocity at mitral level and ascending aorta level was significantly higher during fetal breathing activity than during apnea, suggesting increased shunting of blood flow through the foramen ovale. Acceleration time at outflow tract level demonstrated very little change relative to inspiration and expiration.

Blood Flow Velocity↗

PubMed1991

Flow velocity wave forms in the human fetal ductus arteriosus during the normal second half of pregnancy.

Maximum flow velocity wave forms in the ductus arteriosus were studied longitudinally in 40 fetuses from 18 to 38 wk of gestation at 3- to 4-wk intervals. Median maternal age was 29 y (range 18-41 y), median parity was 1 (range 0-6). All flow velocity wave forms were obtained using a mechanical sector scanner with a continuous Doppler system (carrier frequency 3.5 MHz). The flow velocity parameters studied were peak-systolic, peak-diastolic, and time-averaged velocity and acceleration time. There was considerable variability in measurements between fetuses at any particular gestational age. An increase of ductal flow parameters with advancing gestational age was found. They showed no correlation with heart rate. These results suggest that the normal second half of pregnancy is characterized by a reduction in right ventricular afterload. This may be a result of decreased placental vascular resistance or increased pulmonary vascular flow. Acceleration time in ductal flow velocity wave forms was significantly higher than that observed in the pulmonary artery and ascending aorta, suggesting a lower afterload in the ductus arteriosus compared with the other two outflow tract vessels.

Adolescent↗

PubMed1991

[Effect of fetal behavioral reactions and respiratory movements on the blood flow in the ductus arteriosus].

Relationship between blood flow velocity waveform and fetal behavioral states was studied in 16 normal pregnancies at 37 to 38 weeks' gestation. The peak flow velocity has demonstrated a statistically significant reduction during active sleep, as against that in quite sleep. These data reflect reduced ductal flow and suggest a redistribution in the left-ventricular and right-ventricular output in favor of the left side of the heart during active sleep. In a prospective cross-sectional study of 49 pregnancies (50 fetuses) between 25th and 38th weeks an exponential increase in breathing-related ductal blood flow velocity modulation was observed with advancing gestational age, reflecting the developing pulmonary vascular bed. Fetal ductal flow velocity waveforms were also recorded in 13 cases of prolonged severe oligohydramnios after membrane rupture before 28 weeks' gestation. Normal ductal blood flow velocity modulation values were associated with normal neonatal lung performance, whereas reduced blood flow velocity modulation values were associated with pulmonary hypoplasia. Fetal breathing-related ductal flow velocity modulation appears to be a promising predictor of neonatal lung performance.

Aorta, Thoracic↗

PubMed1990

Ductus arteriosus flow velocity modulation by fetal breathing movements as a measure of fetal lung development.

A test is needed that would accurately predict favorable neonatal lung performance in the presence of prolonged severe oligohydramnios caused by ruptured membranes so that optimal obstetric care can be provided. We propose such a test that is based on the degree of modulation of fetal ductal blood flow velocity by fetal breathing movements after maternal glucose loading. In a prospective cross-sectional study of 49 normal pregnancies (50 fetuses) between 25 and 38 weeks an exponential increase in breathing-related ductal blood flow velocity modulation was observed with advancing gestational age, reflecting the developing pulmonary vascular bed. Fetal ductal flow velocity waveforms were also recorded in 13 cases of prolonged severe oligohydramnios after ruptured membranes before 28 weeks' gestation. Normal ductal blood flow velocity modulation values were associated with normal neonatal lung performance, whereas reduced ductal blood flow velocity modulation values were associated with pulmonary hypoplasia. Fetal breathing-related ductal flow velocity modulation appears to be a promising predictor of neonatal lung performance.

Adult↗

PubMed1989

Fetal anemia.

Explore the source record for details and available documents.

Anemia↗

PubMed1989

Human fetal ductal flow velocity waveforms relative to behavioral states in normal term pregnancy.

In 16 normal pregnancies the relationship between the blood flow velocity waveform and fetal behavioral states at 37 to 38 weeks' gestation was studied. Whereas behavioral state independency was established for the acceleration time, peak flow velocity demonstrated a statistically significant reduction during active sleep, compared with quiet sleep. These data reflect reduced ductal flow and suggest a redistribution in the left-ventricular and right-ventricular output in favor of the left side of the heart during active sleep. Peak flow velocities in the fetal ductus arteriosus were independent of fetal heart rate.

Blood Flow Velocity↗