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Biomedical subjects

K Brockmeier

Publications and source records attributed to K Brockmeier.

35 records · Page 2Linked to original sources
PubMed2001

HIPAA compliance readiness assessment: a case study.

Centura Health, a faith-based, not-for-profit IDS headquartered in Denver, Colorado, recently undertook a rapid assessment to determine its readiness to comply with the standards mandated by the Health Insurance Portability and Accountability Act (HIPAA) of 1996. The assessment process consisted of a business-impact assessment, compilation of results, a gap analysis, and a preliminary business case. The business-impact assessment involved a series of interviews. For the business case, results of the business-impact assessment were compared with the related HIPAA standard to determine the current level of compliance and develop an action plan, for approval by the project steering committee, to correct deficiencies. The HIPAA readiness assessment uncovered numerous areas in which Centura needed to implement changes, particularly with respect to ensuring the security and privacy of patients' paper records.

Colorado↗
PubMed2000

[Use of virtual reality for MRI data of complex vascular structures].

UNLABELLED: During the last years because of the progress in magnetic resonance imaging (MRI) magnetic resonance angiography (MRA) has become a serious alternative to conventional X-ray angiography. The potential of MRA in combination with methods for three-dimensional reconstruction will be presented and different methods for image post-processing are discussed based on a number of cases. The examinations were performed on a clinical 1.5 T magnetic resonance tomograph (Siemens Vision, Erlangen) using conventional MR angiography sequences. The different options of post-processing were carried out online on the console and offline using dedicated workstations (Siemens Virtuoso and CHILI). DISCUSSION: Complex post-processing procedures are applied to different areas like pulmonary vasculature, thoracic aorta, abdominal aorta, and renal transplant arteries. Different diagnostic values can be seen for the variety of three-dimensional reconstruction methods. According to our experience volume rendering has been selected as the method of choice due to the time needed for reconstruction and the information content of the resulting image.

Aortography↗
PubMed2000

Oxygen-mediated pulmonary vasodilation and plasma levels of endothelin-1, atrial natriuretic peptide and cyclic GMP in patients with left-to-right shunt and pulmonary hypertension.

This study was performed to evaluate the role of endogenous endothelin-1 (ET-1), atrial natriuretic peptide (ANP) and cyclic guanosine monophosphate (cGMP) in patients with left-to-right shunt and pulmonary hypertension. Further objectives were to study a possible feedback mechanism between ANP and ET-1 and to examine the influence of ANP on cGMP plasma levels. Finally, the role of these hormones in oxygen-mediated pulmonary vasodilation was examined. Plasma concentrations of ET-1, ANP and cGMP were studied in 39 patients with congenital heart disease and left-to-right shunt. Blood samples were taken from the pulmonary artery and pulmonary vein at cardiac catheterization at baseline and after breathing oxygen for 20 min. Patients were grouped according to the presence or absence of pulmonary hypertension (defined as mean Pp/Ps > or = 0.5). Patients with pulmonary hypertension (n = 18) were found to have significantly higher plasma ANP (665 [59-1358] versus 267 [47-832] pg/ml) and cGMP (21.5 [3.6-82.2] versus 7.8 [0-14.6] nM/L) levels than patients without pulmonary hypertension (n = 21). Pulmonary venous ET-1 plasma concentrations were above normal limits in one patient only. ANP plasma levels were not related to ET-1 and cGMP concentrations. There was no transpulmonary gradient for any of the factors. Pulmonary vasodilation in response to oxygen was found in 7 of 18 patients with PH, but was not associated with significant changes in ET-1, ANP or cGMP plasma concentrations. Patients with congenital heart disease and PH show an increase both in vasoconstrictive and vasodilating factors. The mechanism of oxygen-mediated vasodilation in these patients remains to be elucidated.

Adolescent↗
PubMed2000

Pulmonary vasoreactivity and vasoactive mediators in children with pulmonary hypertension.

We assessed the effect of oxygen, nitric oxide (NO) and prostanoids (prostacyclin and iloprost) on pulmonary hemodynamics and plasma levels of vasoactive mediators in children with pulmonary hypertension (PH). It is not known whether the hemodynamic response during acute vasodilator testing correlates with changes in plasma levels of endothelin-1 (ET-1), cyclic guanosine monophosphate (cGMP) and cyclic adenosine monophosphate (cAMP). In this retrospective analysis 14 children at a median age of 4 years and 3 months [1.8 months-13 years] with a median pulmonary resistance to perfusion of 10.1 [2.1-37.7]. Wood-Units x m2 were studied. Diagnoses included PH due to congenital heart disease (AVSD n = 5; VSD n = 2; PDA n = 1) or unknown causes (n = 6). The ratios of pulmonary/systemic pressure (Pp/Ps) and of pulmonary/systemic resistance (Rp/Rs) were recorded a) at baseline, b) during oxygen (FiO2 = 1.0) and c) while on NO (80 ppm max., at FiO2 = 0.23). In 13 out of 14 children prostanoids were given additionally: 7 received prostacyclin (i.v.) and 6 were given iloprost which was nebulized. ET-1, cGMP and cAMP were measured in blood samples taken from the pulmonary vein or left ventricle at baseline, during increased FiO2, during NO inhalation and while on prostanoids. Pulmonary vasodilation in response to oxygen was found in 2/14 patients. 4/14 patients responded to NO and 2/7 to prostacyclin i.v. Increased FiO2 was not associated with changes in plasma concentrations of ET-1, cGMP or cAMP. NO inhalation was followed by an increase in cGMP levels from 10.9 [5.5-55.4] nM/L to 21.3 [6.4-76.3] nM/L independent from the individual hemodynamic response. Oxygen and NO identify most children with reactive pulmonary vasculature. cGMP plasma levels do not correlate with individual hemodynamic responses to NO.

Adolescent↗
PubMed1999

[Transesophageal electroconversion of atrial reentrant tachycardias early or late following surgery for congenital heart disease].

Atrial reentrant tachycardias (ART) are a potentially life-threatening complication in survivors of congenital heart disease surgery. From July 1993 to December 1997, temporary transesophageal pacing was used to convert 29 tachycardia episodes in 19 patients. At the time of the first tachycardia episode, patients' ages were 1 month to 26 years (mean 9.8 yrs). Time from operation to onset of first tachycardia episode ranged from 1 day to 19 years. Onset was within the first 2 weeks postoperatively in 6 patients and occurred later in 13 patients (1 to 19 years after operation). Postoperative pacemaker implantation had been performed in 2 pts; 17 of 19 pts were receiving antiarrhythmic medication. After placing a quadripolar transesophageal catheter, atrial and ventricular signals were recorded and atrial stimulation performed. Atrial cycle length of tachycardia ranged from 160-380 ms with 1:1 to 4:1 AV conduction. Temporary transesophageal pacing was performed following an algorithm starting with 4 extrastimuli (20 ms below atrial cycle length of tachycardia). Tachycardia terminated in 27 of 29 cases (93%) without complications. In 3 cases, conversion was achieved by pacing after amiodarone 5 mg/kg i.v. After tachycardia conversion, sinus- or pacemaker rhythm was present in 20 cases. In 9 cases atrial fibrillation was recorded; spontaneous conversion to sinus rhythm occurred after a maximum of 3 min (7 cases) or persisted and required direct current cardioversion (2 cases). In conclusion, transesophageal atrial pacing is an effective, relatively noninvasive method for conversion of atrial reentrant tachycardias after operation for congenital heart disease.

Adult↗
PubMed1998

Prediction of normal QT intervals in children.

Measuring QT intervals in individual children is of great importance, particularly in view of increasing evidence linking long QT syndrome to subsequent risk for sudden death. Three hundred seventy-three healthy subjects, 185 women and 188 men, aged 5.2 to 16.5 years, were investigated with a 12-lead-standard electrocardiogram (ECG). Values for predicted QTp50 and QTp95 (percentiles) were calculated by using the cycle length (RR interval [RRI]) and the measured QT interval. We used multiple regression analysis to test the influence of possible important variables and the resulting data were used to generate tables. Additionally, predicted QTp values were compared to QTc values after Bazett's correction. RRI, body height, age, and sex turned out to influence the QTp values most. For clinical use, data are presented in tabular form by RRI and age for both genders. The tables are of great clinical value in predicting the upper limits of normal QTp95 for individual children. Bazett's correction tends to underestimate the values found in our data when heart rate increases.

Adolescent↗
PubMed1998

Left ventricular diastolic function in infants, children, and adolescents. Reference values and analysis of morphologic and physiologic determinants of echocardiographic Doppler flow signals during growth and maturation.

OBJECTIVES: The aim of this study was to set up reference values for Doppler flow-derived left ventricular filling parameters and to evaluate physiologic determinants of changes in signal expression related to maturation. BACKGROUND: In left ventricular diastolic function studies, age-related modulations in signal expression are observed. Assuming degenerative myocardial changes to be absent during childhood and adolescence, the determinants of these modulations must be different from those suspected in adults. METHODS: Pulsed wave Doppler signals from the mitral valve tip region were recorded in 329 healthy subjects aged 2 months to 39 years. Multiple linear regression was used to evaluate statistical relations between Doppler flow signals and stroke volume in the mitral valve area. RESULTS: Increasing early filling time velocity integral throughout maturation caused a decrease in atrial filling fraction from 0.34+/-0.06 to 0.24+/-0.04 (p < 0.005). Peak flow velocities during atrial systole decreased from infancy to adolescence (66+/-15 to 41+/-10 cm/s). Main effects on signal modulation were caused by heart rate, stroke volume and mitral ring area with a linear model fit (R2) of 0.79 for early filling phase (E)-time velocity integral, 0.6 for atrial filling phase peak velocity 0.84 for total E duration and 0.73 for E deceleration time. Atrial filling phase-time velocity integral, albeit significantly dependent on heart rate, was stable throughout growth. CONCLUSIONS: During infancy and childhood, the stroke volume crossing the mitral valve is a main modulator for early filling phase (E)-time velocity integral and diastolic time intervals during early filling, whereas atrial filling phase parameters are mainly dependent on heart rate. This results in a more pronounced atrial filling during infancy and childhood.

Adolescent↗
PubMed1997

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↗
PubMed1997

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↗
PubMed1995

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↗
PubMed1994

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↗
PubMed1990

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↗
PubMedDate not supplied

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↗
PubMedDate not supplied

[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↗