Magnetocardiographic turbulence analysis in patients with the long QT syndrome.
Explore the source record for details and available documents.
Adolescent↗
Biomedical subjects
K Brockmeier
Publications and source records attributed to K Brockmeier.
High-pass-filtered magnetocardiogram and cardiomyopathy in patients with type 1 diabetes mellitus.
Prolonged and/or fractionated depolarization due to tissue degeneration of the ventricular myocardium is a feature of cardiomyopathy. Signal averaged electrocardiography uses high-pass filters of the Butterworth type to quantify, noninvasively, fractionated high-frequency components at the end of the QRS complex. In this study a finite impulse response high-pass filter of the 90th order (cutoff at 37 Hz) was applied to magnetocardiograms (MCGs) and high-resolution electrocardiograms (ECGs) order to quantify high-frequency components throughout the myocardial depolarization. Additionally, late-potential analysis on the signal-averaged ECG was performed. A prospective investigation was made of 23 cardiologically asymptomatic patients, 11 females and 12 males, with type I diabetes mellitus. Their mean age was 21.7 years (range, 13-34 years). The mean duration of diabetes was 14 years (range, 1-27 years). Data were compared with those of 22 control subjects (12 females, 10 males) of mean age, 23.2 years (range, 11-35 years). The ECGs and MCGs were simultaneously recorded and signal-averaged, digitally filtered, and quantified by a score obtained by multiplying the amplitude variation of the signal by the number of maximal/minimal in the QRS complex. Echocardiograms were used to calculate the left ventricular mass and to document the presence of cardiomyopathy. Scores were higher in the MCGs of with type I diabetes mellitus than in the control subjects (P < .001). High scores correlated with an increased left ventricular muscular mass index (P < .05) and duration of the diabetes (P < .05). The high-resolution ECG, processed analogously, showed similar results in relation to left ventricular mass (P = .06) and duration of diabetes (P = .07), respectively (nonsignificant). No late potentials were found. These findings suggest that using a linear-phase high-pass finite impulse response filter may be useful for the noninvasive identification of patients with cardiomyopathy who exhibit possible disturbances of intraventricular depolarization. Our findings also suggest that analysis using the total QRS complex, rather than the final part of the QRS complex only, may improve identification of patients at risk.
Adolescent↗
Magnetocardiography and 32-lead potential mapping: repolarization in normal subjects during pharmacologically induced stress.
Signals from 37 magnetocardiographic sensors and simultaneously recorded 32 ECG leads were obtained in three healthy male subjects (including two reinvestigations). After recordings at rest, the heart rate was increased by pharmacologic stress (117 to 142 beats/min). Comparison of the repolarization of rest and stress showed substantial changes in the magnetocardiogram (MCG) up to T wave inversions during stress. In the ECG only junctional ST-T segment shifts were present. For quantification, correlation coefficients between pairs of rest and stress MCG and rest and stress ECG distributions were calculated for the same time instant at the beginning of T wave under rest and stress conditions. In addition, equivalent electrical current dipole moment and magnetic dipole moment vectors were calculated from the MCG, and their change from rest to stress evaluated. Correlation coefficients for MCG comparison ranged from 0.3 to 0.5; ECG comparison suggested much less change from stress, ranging from 0.7 to 1.0. Current dipole moment changes at T wave onset were marginal; in contrast, the magnetic dipole moment changed substantially. Since the magnetic dipole reflects vortex currents, changes in its intensity and/or orientation during repolarization suggest this as the biophysical basis of the striking difference in the response of the MCG and ECG to pharmacologic stress. Normal ECG findings at rest and under stress in healthy subjects support the conclusion that the repolarization changes in the MCG were of nonpathologic origin.
Adult↗
Plasma endothelin-1 in patients with left-to-right shunt.
Endothelin-1 (ET-1) has been implicated in the pathogenesis of pulmonary vascular disease in patients with congenital heart disease. We studied the effect of pulmonary blood flow on plasma ET-1 concentrations. Systemic venous, pulmonary arterial, and pulmonary venous blood samples were obtained from 40 patients with atrial septal defect II (n = 21), ventricular septal defect (n = 10), persistent ductus arteriosus (n = 6), and complete (n = 2) and partial (n = 1) atrioventricular canal at cardiac catheterization and analyzed by radioimmunoassay. Median age (range) was 5.2 years (8 months to 66 years), and the resistance ratio (Rp/Rs) was 0.08 (0.03 to 0.67). Pulmonary vein to pulmonary artery ET-1 ratio in patients with "high flow" (n = 26, Qp/Qs > or = 1.5; ET-1 ratio = 0.8) did not differ from those with "low flow" (n = 14, Qp/Qs < 1.5; ET-1 ratio = 1.0). We conclude that an increase in pulmonary blood flow alone does not result in an increase in plasma ET-1.
Adolescent↗
Magnetocardiography and exercise testing.
Twenty healthy male subjects (age range, 15-25 years; median, 21 years) underwent magnetocardiography during physical exercise. Significant ST-segment displacements of the magnetic signal were found during exercise at a heart rate of 120 beats/min compared to the magnetic signal at rest (P < .001). Since no significant ST-segment changes were found in the electrocardiogram recorded simultaneously with the magnetocardiogram, it is concluded that the magnetocardiogram shows junctional ST-T segment changes earlier than the electrocardiogram.
Adolescent↗
Syndrome of the posterior and anterior root in a late isolated CNS relapse of c-ALL. Case report.
A 15 year-old girl who had c-ALL diagnosed in 1982 was presented in our clinic suffering from an ascended flaccid paresis and dysaesthesia of both legs. These are typical symptoms of polyradiculitis of the nerve roots L2-S2. A lumbal puncture revealed a pleocytosis with lymphoblasts which were up to 40% CD10 (cluster of differentiation) up to 70% CD19 and TdT (terminal transferase) positive. The diagnosis of late isolated CNS relapse was made. It is assumed that local residual infiltrations of leukemic cells into the nerve roots L2-S2 got into cell cycle and caused these rare CNS leukemia symptoms. Therefore the value of a craniospinal irradiation to prevent a CNS and systemic relapse is discussed.
Adolescent↗
X-chromosomal (p21) muscular dystrophy and left ventricular diastolic and systolic function.
In order to screen for cardiac abnormalities, we prospectively studied 15 patients (age 8-25 years, mean 15.5 years) with Duchenne's (DMD) (n = 9) and Becker's (BMD) (n = 6) muscular dystrophy using the echocardiogram. Data were compared to a control group of 92 healthy individuals (age 7.9-25 years, mean 14.3 years). Left ventricular filling in diastole showed a different pattern when comparing echocardiographic Doppler results in patients and controls: Patients had lower peak velocity of early left ventricular diastolic filling (E-vmax)(P < 0.0001) and smaller time velocity integral of the E-wave (E-tvi)(P < 0.0001). In contrast, the atrial component (A-vmax, A-tvi) of diastolic filling in DMD/ BMD showed no significant difference to controls. The mean area of the mitral valve orifice was significantly larger in patients (P < 0.0001) without presence of mitral regurgitation. Systolic left ventricular function was significantly impaired in the DMD/BMD group; we found lower heart rate corrected fiber shortening velocity VCFc (P < 0.001) and higher peak systolic wall stress (P < 0.001) in DMD/BMD. In 8 of 15 patients, peak systolic wall stress was above 95th percentile of controls. In 6 of 15 patients, VCFc was lower than the 5th percentile of controls. Systolic and diastolic myocardial impairment was found even in young patients and at low stages of disability--equally among patients with DMD or BMD. Diastolic left ventricular impairment predominantly affected the early diastolic filling, but atrial compensation was poor. Peak systolic wall stress measurements were particularly useful in patients with CMP, reflecting the left ventricular afterload.
Adolescent↗
[Long-term study of anthracycline-induced cardiomyopathy in children and adolescents].
In order to detect changes in cardiac function, electrocardiographic, echocardiographic and radiologic studies were performed in 71 patients (age 1-26 yrs) who had been treated at the University Children's Hospital Berlin because of malignant diseases according to protocols of the DAL/GPO and had received anthracyclines (doxorubicin or daunorubicin) at cumulative doses up to 480 mg/m2 (median 280 mg/m2). Clinically overt cardiomyopathy was observed in one girl and required transient administration of digoxin. In 2 patients echocardiographic changes led to a reduction of the scheduled anthracycline doses. No patient died from congestive heart failure. During treatment, an increase in the cardiothoracic index was observed in 14 children, and in 16 the ECG showed pathological findings. A decrease in contractility to 25% or less as detected by ultrasound was seen in 15 patients. More than 50% of patients developed echocardiographical signs indicating an impairment of myocardial function. However, persistent changes were only found in 1 patient after discontinuation of treatment. Long-term echocardiographic follow-up studies for 4-48 months (median 14 months) after completion of anthracycline therapy were performed in 18 patients and the findings compared to matched-pair controls. The observed M-mode parameters were completely normal, and the ejection fractions calculated from the two-dimensional ultrasound investigations were in the normal range but slightly diminished compared to controls. Cardiac ultrasound is a non-invasive, reproducible and tolerable procedure for early detection of an anthracycline cardiomyopathy. In our patients, time of occurrence and the extent of pathological changes were not associated with the cumulative applied anthracycline doses.(ABSTRACT TRUNCATED AT 250 WORDS)
Adolescent↗