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Biomedical subjects

H Netz

Publications and source records attributed to H Netz.

64 records · Page 4Linked to original sources
PubMed1977

Mammalian embryo: a model for congenital prolonged QT syndrome.

The QT interval has been studied in ECG in mouse and rat embryos during two stages of development. The QT interval during the early stage of development is prolonged and an ST segment clearly exists. Both disappear during fetal development and do not exist in adult animals in which the T wave immediately follows the QRS. Mammalian embryos have therefore been proposed as a model for the study of QT prolongation. It is suggested that the origin of the QT prolongation in the young embryos is caused by the prolonged duration of the action potentials of the primordial cardiac tissue. During embryonic development this tissue becomes organized as a conductive system surrounded by "neomyocardial" tissue with a shorter duration of action potential, which causes the shorter QT interval at this stage. Our working hypothesis is that the pathogenesis of the prolonged QT syndrome in children could be interpreted as an incomplete or delayed differentiation between the primordial or primordial-like myocardium retaining prolonged action potential duration, and "neomyocardium" with short duration.

Animals↗
PubMedDate not supplied

Echocardiographic assessment of left ventricular size and function in normal children from infancy to adolescence: acoustic quantification in comparison with traditional echocardiographic techniques.

The purpose of this study was to establish normal left ventricular acoustic quantification (AQ) reference values for children from infancy to adolescence and to compare AQ-derived parameters with traditional M-mode and Doppler indices. We studied 150 normal, healthy children aged 2 days to 14 1/2 years. Left ventricular parasternal end diastolic area and left ventricular end diastolic volume calculated by AQ were linearly related to the body surface area to the 1.1 and 1.4 powers. AQ parasternal peak filling rate and atrial fractional area change in the neonatal period were 140% and 142% of the adolescent's values, respectively, and decreased to 110% and 112% by 36 months of age. The duration of the rapid filling phase and the rapid filling contribution, as identified by AQ, was shorter or lower than that measured by the Doppler method. Interobserver variability of AQ parameters ranged from 8.1% for the ejection fraction to 18.2% for the peak filling rate. Manual biplane determinations of volumes were slightly higher than AQ calculations with highly significant correlations (p <0.001). Our data permit the determination of normal ranges of AQ parameters in relation to body surface area or age.

Acoustic Impedance Tests↗
PubMedDate not supplied

["Real time"-3D-echocardiography: a valuable new tool in preoperative assessment of complex cardiac defects].

Evaluating complex cardiac defects in small children preoperatively requires multiple diagnostic procedures including echocardiography, but also the invasive methods such as cardiac catheterisation, computer-tomography and magnetic resonance imaging. We tried to assess the complex anatomy of the atrioventricular valves in atrioventricular septal defect using bedside real-time three-dimensional echocardiography and comparing these results to the anatomic findings at the time of operation.

Age Factors↗
PubMedDate not supplied

[Heart transplantation in infants--a new option].

Nowadays orthotopic heart transplantation is world wide accepted as a therapeutic concept in endstage congestive heart failure. Concerning infants, there are still major objections against this kind of therapy and especially in our country exists only very limited experience. Since march 1988 we have performed an orthotopic heart transplantation in 10 pediatric patients: 5 infants (2-16 years of age) with congestive cardiomyopathy, 1 newborn with endocardial fibroelastosis, 3 newborns with hypoplastic left heart syndrome, and finally 1 infant at the age of 2 years with AV-canal and hypoplastic left ventricle. Until now 6 infants survived and are all at home and in good clinical condition. There have been no signs for chronic rejection or graft atherosclerosis up till now. As demonstrated in the example of the newborn, in whom we performed the first successfully orthotopic heart transplantation in Germany, the clinical course and quality of life are superior to those after other palliative procedures in complex cardiac malformations.

Adolescent↗
PubMedDate not supplied

[Sinus node reentry tachycardia in a newborn infant].

A case of sinus node reentrant tachycardia in a newborn is reported. The diagnosis was made by surface ECG. Rate and duration of the tachycard attacks could be influenced successfully by verapamil in a high dosis.

Digoxin↗
PubMedDate not supplied

Short-term testing of heart rate variability in heart-transplanted children: equal to 24-h ECG recordings?

INTRODUCTION: Heart rate variability (HRV) is reduced in adults and children after cardiac transplantation. Testing of HRV has been used to assess re-innervation of the cardiac graft; its reliability in ruling out acute graft rejection is still under investigation. This study used a short-term test on HRV in 23 heart and heart-lung transplanted children and adolescents and compared the results with 24-h ECG recordings. PATIENTS AND METHODS: Twenty-three subjects (16.3+/-4.2 yr; 10 females) underwent a 10-min HRV test at two occasions and one 24-h ECG. HRV was calculated according to the time domain method (RR interval, standard deviation of RR interval) and the frequency domain method (total power, LF and HF for assessment of sympathovagal modulation of heart rate). RESULTS: Correlation between the short-term tests and 24-h ECG was high with regard to the frequency domain analysis of HRV. Correlation was less pronounced in the time domain method. CONCLUSIONS: In heart and heart-lung-transplanted children and adolescents, due to reduced overall HRV short-term testing may give as reliable data as 24-h ECG. Therefore, especially when power spectral analysis has to be performed as a longitudinal assessment of re-innervation of the cardiac graft, short-term testing may offer an easily applicable and non-invasive diagnostic tool. Further studies are warranted to investigate whether HRV testing may contribute to rule out acute graft rejection.

Adolescent↗