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Biomedical subjects

O Daniels

Publications and source records attributed to O Daniels.

14 recordsLinked to original sources
PubMed2005

New reference values for echocardiographic dimensions of healthy Dutch children.

AIM: To renew the echocardiographic reference values of heart dimensions in healthy children. METHODS AND RESULTS: Group 1 consisted of 587 children, of which 361 boys and 226 girls, age from birth to 18 years, body weight over 2500 g, who visited the Pediatric Cardiology outclinic during the period January 2000 till March 2004. All included children were diagnosed as normal, or as having innocent heart murmur. The second group was taken from an earlier study and comprised 160 children (77 boys and 83 girls). The echocardiographic measures were taken from conventional M-mode recording of the left ventricle (LV) parasternal long axis view. End diastolic septal (IVS) and LV posterior wall thickness (LVPW) and end diastolic as well as end systolic LV intracavity dimensions were retrospectively analyzed. The regression lines from all measured sizes are significantly different from those collected in the early eighties. Especially the thickness of the IVS is smaller. The regression lines are independent of gender. CONCLUSIONS: New reference values have been found which should replace the presently used ones. There is no difference between boys and girls. Why the muscular wall thicknesses are thinner than found 20 years ago needs to be further explored.

Adolescent↗
PubMed2002

The influence of ductal left-to-right shunting during extracorporeal membrane oxygenation.

BACKGROUND/PURPOSE: The aim of this study was to analyze whether a ductal left-to-right (L-R) shunt will prolong extracorporeal membrane oxygenation (ECMO) in neonates with severe pulmonary hypertension. This report discusses the onset and termination of a ductal L-R shunt and its potential influences on ECMO when pulmonary hypertension decreases during venoarterial bypass. METHODS: Twenty-nine neonates were monitored during veno-arterial ECMO, using bedside echocardiography with 12-hour interval observations. RESULTS: Up to 43% of the patients showed this type of shunt already after 12 hours on bypass. In total, this type of ductal shunt was found between 12 and 72 hours on ECMO in 62% of the patients. After 72 hours, the ductal L-R shunt no longer was detected. In 38% of the patients, no ductal L-R shunt was found during ECMO. Comparisons between these 2 patient groups showed a significantly longer ECMO duration in patients with ductal L-R shunt (P <.007). The mean prolongation time was 46 hours. Also, a significant decrease of left atrium to aorta ratio (P <.01) was observed during ECMO in the ductus group after closure of the duct, illustrating the decrease in volume load for the left heart and lungs. CONCLUSIONS: Ductal L-R shunting is related with a substantial prolongation of the ECMO course (mean prolongation of almost 2 days). The authors suggest that on one side, the ductal L-R shunt will lead to pulmonary hypercirculation and on the other side, postductal stealing from the descending aortic circulation will lead to prerenal failure. Possibly because of interactions with pulmonary and renal function, a ductal L-R shunt will, among other factors, interfere with weaning from ECMO, resulting in a prolonged bypass time.

Echocardiography↗
PubMed2001

Effects of growth hormone treatment on left ventricular dimensions in children with Noonan's syndrome.

OBJECTIVE: To study the effects of long-term growth hormone (GH) treatment on left ventricular (LV) dimensions in children with Noonan's syndrome (NS). METHODS: Echocardiographic measurements of LV dimensions were performed before and during GH treatment in 27 participants (21 boys, 6 girls) in a partly controlled 3-year trial of high-dose GH treatment (0.15 IU/kg/day). Nineteen children had a congenital heart defect, 1 of them had hypertrophic obstructive cardiomyopathy. In the first 3 years, the children were assigned to 1 of 2 groups: group A with discontinuation of GH treatment in the 3rd year, or group B without GH treatment in the 1st year. After the 3rd year, 12 of the 27 children were followed up for 2 additional years to evaluate the long-term effects of GH treatment on the heart. RESULTS: At baseline, LV internal diameters were smaller, while posterior wall thickness were thicker than normal. Over the 1st year, changes in LV dimensions were comparable between the 2 groups. No significant differences were found in LV dimensions between the situation at baseline and after 4 years of GH treatment. CONCLUSION: Long-term high-dose GH treatment does not have clinically significant adverse effects on LV dimensions in children with NS.

Adolescent↗
PubMed1989

Repeatability of Doppler ultrasound measurement of blood flow velocity and its variability in the supraclinoid segment of the internal carotid artery in preterm newborns.

Accuracy of transfontanellar Doppler ultrasound measurement of blood flow velocity and its variability in the supraclinoid segment of the internal carotid artery was studied in preterm newborns. Measurements were performed in duplicate, on a well defined site, under negligible angle of insonation, and during stable physical condition. The measurements included the base value and variability over 20 seconds, for: diastolic velocity; mean velocity; systolic velocity; resistance index; diastolic time interval; systolic time interval; heart beat duration. As a measure of accuracy the coefficient of repeatability was calculated for each parameter. Coefficients several times smaller than the range of measured values, were found for most parameters. These parameters and their coefficients include: diastolic velocity (base value 3.1 cm s-1, variability 1.6 cm s-1); mean velocity base value 3.1 cm s-1; systolic velocity base value 4.5 cm s-1; resistance index (base value 0.13, variability 0.08); diastolic time interval base value 25 ms; systolic time interval base value 27 ms; heart beat duration base value 27 ms. Thus, Doppler ultrasound enables differentiation within the biological variation of certain properties of cerebral blood flow.

Blood Flow Velocity↗
PubMed1989

The effect of respiration on diastolic blood flow velocities in the human heart.

This study was performed to evaluate the effects of respiration on diastolic blood flow velocity and its relevance for the determination of pulsed Doppler reference values from diastolic blood flow. Doppler signals were recorded from both the atrial and ventricular sides of the mitral valve and the tricuspid valve in 215 healthy volunteers (120 males and 95 females, with ages ranging from 1-65 years). Respiratory signals were recorded simultaneously by a mercury strain gauge around the thorax. From the medians of Doppler spectra the maximum velocity during early diastole (VmaxE), during atrial contraction (VmaxA) and the ratio between VmaxE and VmaxA (EA ratio) were obtained. On the atrial side of the tricuspid valve, VmaxE and VmaxA were significantly higher during inspiration than during expiration. On the ventricular side of the tricuspid valve, this was only found for VmaxE. On the atrial side of the mitral valve, VmaxE and VmaxA were significantly lower during inspiration than during expiration. At the ventricular side of the mitral valve, this was found only for VmaxE. No significant effect of respiration was found on the EA ratio. We conclude that there is a respiration-related effect on VmaxE and VmaxA. However, no significant effect is found on the EA ratio. Thus, for the determination of the EA ratio in intersubject studies, information about the respiratory cycle is not relevant.

Adolescent↗
PubMed1988

Limits of reproducibility of mitral pulsed Doppler spectra.

The total intrinsic variability of pulsed Doppler spectra of mitral blood flow was evaluated in this study. Doppler examinations were performed in 10 normal volunteers (7 men, 3 women), ages 29 to 57 years (mean 41) with an interval period of 3 months. The recordings were made in the apical 4-chamber view, using a 2.25-MHz transducer. The sample was placed approximately 1 cm proximal (left atrium) and 1 cm distal (left ventricle) from the middle of the anulus of the mitral valve at the onset of diastole. Processing of the raw Doppler spectra was done in a way that avoided subjective manipulation by the investigators. Mitral peak velocities, accelerations and spectral widths were measured in early diastole and late diastole. From the parameters under investigation, maximal velocities showed the best reproducibility with a range of coefficients of variation of 9 to 13%. Peak acceleration in early diastole and spectral widths showed rather large coefficients of variation, ranging from 19 to 30 and 14 to 24%, respectively. Mitral pulsed Doppler spectra in the left atrium were more reproducible than in the left ventricle.

Adult↗
PubMed1988

Reference values for pulsed Doppler signals from the blood flow velocity on both sides of the pulmonary valve.

Pulsed Doppler signals were recorded from the pulmonary artery and the right ventricular outflow tract in 215 healthy subjects (120 males, 95 females; 1-65 years). Amplitude spectra from these Doppler signals were stored in digital form together with adjustment data for the instrument and the simultaneously recorded ECG. From these Doppler spectra the median of the maximal velocity (Vmax), the maximal acceleration (Amax) and the dispersion of the velocity distribution around Vmax (width) were calculated. These three median values were used to characterize the Doppler spectra and to define normal values for bloodflow velocities. Thus, calculations were made without observer interacting using a well-defined computer program. The effect of age, gender, body surface area and heart rate were studied. Reference ranges were calculated. There is a slight decrease of the median value of Vmax and Amax in the pulmonary artery during lifetime from 80 to 70 cm s-1 and from 1,200 to 800 cm s-2, respectively. On the other hand, there is no correlation between age and Vmax and Amax in the right ventricular outflow tract. The width of the spectra increases with age at both sites. No significant changes with age were seen with the other variables.

Adolescent↗
PubMed1987

Reference values for pulsed Doppler signals from the blood flow on both sides of the aortic valve.

Pulsed Doppler signals were recorded in 215 healthy subjects, 120 males and 95 females, between 1 and 65 years of age. The measurements were performed in the left ventricular outflow tract (LVOT) and in the ascending aorta (AAO). Amplitude spectra from the Doppler signals were stored in digital form together with adjustment data for the instrument, the simultaneously registered ECG and respiration signal. The maximum velocity (Vmax), the maximum acceleration (Amax) and the width of the velocity distribution around Vmax (width) were derived from these spectra and used for the characterization of the signals. These parameters were computed without observer interaction using a computer program. Effects of age, sex, body surface area, heart rate and respiration were studied. Reference ranges were calculated. The following conclusions can be drawn: Vmax and Amax in the AAO decrease clearly with increasing age from approximately 100 to 60 cm s-1 and from 2000 to 1000 cm s-2 (medians), respectively. The variation of the width in the AAO is greater for people over 45 years. Vmax, Amax and width in the LVOT increase slightly with advancing age from approximately 60 to 80 cm s-1, 800 to 1000 cm s-2 and 12 to 15 cm s-1 (medians), respectively. These parameters of flow were either unrelated or only weakly related to other physiological variables in this study group.

Adolescent↗
PubMed1987

[Myocarditis and thrombosis].

Thrombo-embolic events are important complications of myocarditis, associated with a dilated and decreased contracting left ventricle. With echocardiography it is possible to prove the diminished left ventricular function as well as the presence of a thrombus. Early anti-thrombotic therapy is indicated in these cases. This will be demonstrated in a case history.

Echocardiography↗
PubMed1976

Cardiomyopathy and short stature associated with mitochondrial and/or lipid storage myopathy of skeletal muscle.

The patient described in this report was an 11-year-old girl with a negligible heart murmur. The length was below 10th percentile. There appeared to be a cardiomyopathy with, at that moment, no signs of obstruction. There were no evident clinical symptoms of myopathy of skeletal muscle. However, electromyography was myopathic. Biochemical studies revealed no abnormalities. In muscle biopsy sections, the Sudan staining reactions revealed the presence of large amounts of sudanophilic droplets, predominantly in type I fibers. Electronmicroscopy demonstrated lipid excess and accumulations of enlarged, mostly rounded mitochondria in a subsarcolemmal location, with closely packed cristae. In many mitochondria a dense osmiophilic material was present in the spaces between the cristal membranes. The patient's parents were first cousins. One of her brothers who died at the age of 4 1/2 years presumably suffered from the same disease. The pattern of inheritance is most probably autosomal recessive.

Adenosine Triphosphatases↗