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Biomedical subjects

R M Schieken

Publications and source records attributed to R M Schieken.

At least 55 records · Page 3Linked to original sources
PubMed1988

Left ventricular mass and exercise responses predict future blood pressure. The Muscatine Study.

Increased blood pressure and left ventricular mass are associated with increased morbidity and mortality in adults with coronary heart disease. To define the predictors of subsequent childhood blood pressure and left ventricular mass, serial echocardiograms and blood pressure responses during exercise were studied in 274 children aged 6 to 15 years, whose systolic blood pressures were in the high, middle, or low range. Persistence of rank order for left ventricular mass and blood pressure, at rest and during exercise, was maintained over a mean follow-up period of 3.4 years, with correlations ranging from 0.33 to 0.44. Subsequent systolic blood pressure was best predicted from initial resting and maximal exercise systolic blood pressures and left ventricular mass. Subsequent left ventricular mass was best predicted from initial left ventricular mass and maximal exercise diastolic blood pressure, but resting systolic blood pressure did not add to this latter prediction. Since left ventricular mass relates best to exercise blood pressure and not to resting blood pressure, left ventricular mass may provide an integrated view of the effects of blood pressure both at rest and during stress. We speculate that increased left ventricular mass in childhood may be an important predictor of subsequent hypertension and its consequences.

Adolescent↗
PubMed1987

Measurement of left ventricular wall mass in pediatric populations.

This paper reviews the techniques for obtaining technically adequate echocardiograms for epidemiologic studies. When these techniques were applied to studies of pediatric populations the following objectives were achieved: reproducible echocardiograms, observations about the relationship of echocardiographic variables to cardiovascular variables, and information about the relationship of echocardiographic and electrocardiographic variables to each other and to blood pressure. We documented the precision of M-mode left ventricular chambers and dimensions, interobserver and intraobserver variability, and the day-to-day variability of these measures. Left ventricular wall mass was significantly larger than expected for age and body size in children with persistently elevated blood pressure. The relationship between the echocardiographic and electrocardiographic variables was poor. Moreover, the electrocardiographic measures of ventricular hypertrophy did not correlate with blood pressure.

Adolescent↗
PubMed1986

Hemodynamics in childhood hypertension.

Children with elevated systolic blood pressure have a wide range of cardiac output. We investigated the mechanisms regulating resting and exercise blood pressure in 264 children who were selected from the low, middle, and upper quintile of the distribution of blood pressure of an entire school population. We identified patterns of response to exercise that correlated both with resting cardiac output and resting blood pressure. During isometric exercise, systolic blood pressure adjusted for age and body size increased in all groups. The low group mean pressure remained significantly lower than the high group's pressures throughout the entire exercise period. Body size adjusted group systolic and diastolic blood pressure level differences existed during dynamic exercise. The product of the systolic blood pressure times the heart rate in the high blood pressure group was significantly higher throughout dynamic exercise than in the other two groups. Elevated resting resistance was correlated with elevated resistance during isometric exercise and elevated diastolic blood pressure during dynamic exercise. Cardiac index had a significant negative correlation to age (r = -0.58) at all levels of blood pressure. This observation, in children, lends some support to the concept of evolution from a hyperkinetic circulation in early childhood to a circulation with lower cardiac output and more elevated systemic vascular resistance at an older age.

Age Factors↗
PubMed1982

Communicating hydrocephalus secondary to venous complications following intraatrial baffle operation (mustard procedure) for d-transposition of the great arteries.

A 39-month-old male had macrocephaly and communicating hydrocephalus secondary to superior vena cava (SVC) obstruction which was a postoperative complication of an intraatrial baffle operation (Mustard procedure) performed at age 10 months. Computerized tomography revealed progressive hydrocephalus. Cardiac catheterization showed an SVC pressure of 24 mm Hg. IVC and systemic vein atrium pressures were 5 mm Hg. Cineangiograms showed huge azygos collaterals from SVC to IVC. The operation was revised using a Dacron baffle instead of the original pericardial baffle. Nine months postoperatively, the head circumference was 55.0 cm and there was no clinical evidence of SVC obstruction.

Child, Preschool↗
PubMed1982

Spontaneous closure of a coronary artery fistula in childhood.

An infant with a symptomatic coronary artery fistula, documented by angiography, is presented. By age 5 years, clinical evidence of the fistula was no longer present. Repeat cardiac catheterization confirmed spontaneous closure of the coronary artery fistula. More information regarding the natural history of a coronary artery fistula is required before an elective surgical approach can be recommended in all asymptomatic children.

Cardiac Catheterization↗
PubMed1982

Repair of large ventricular septal defects in infants and small children.

It is possible to achieve excellent results for primary closure of ventricular septal defects regardless of the age of the patients when surgical intervention is required. Thirty-two severely symptomatic patients, age 1-24 months, with large ventricular septal defects (m Qp/Qs = 3.4, m R VSD = 4.0), had primary repair of the defects with one (3%) hospital death. Seven patients (22%) had increased pulmonary vascular resistance ranging from 5.4 to 12 units/m2. It was possible to close the ventricular septal defect through the right atrium in 26 patients (81%). Pulmonary artery banding was not performed in any patient with isolated ventricular septal defect during the period of this study. The 31 survivors have been followed an average of four years, and 30 of them are remarkably improved and remain New York Heart Association Class I or II. Only one patient, with obstructive pulmonary vascular disease (pulmonary resistance = 12 U/m2), died suddenly 16 months after operation. Follow-up catheterization was offered to all patients, and to date, 18 (60%) have been restudied. These hemodynamic data show that pulmonary vascular resistance after surgery is usually normal or only minimally elevated; except for one patient with a large residual ventricular septal defect, functionally significant left to right shunts were eliminated. These results and the analysis of results of combined series reported in the literature for primary and staged operations for the continued practice of primary repair of isolated large ventricular septal defects in infants and children who require surgery.

Age Factors↗
PubMed1982

Electrocardiographic measures of left ventricular hypertrophy in children across the distribution of blood pressure: the Muscatine study.

We sought to test the effectiveness of the ECG as a measure of increased left ventricular wall mass in children with high blood pressure. One hundred eighty-one children, ages 9-18 years, were selected from the lowest, middle and highest quintile of systolic blood pressure from the Muscatine Study, based upon two biennial school screenings. After correction for age, sex, height, weight and skinfold thickness, children with the highest blood pressure had increased echocardiographic left ventricular wall mass (p less than 0.02). Voltage measurements of maximum R and S waves in the standard and precordial leads were measured by computer. We correlated blood pressure and echocardiographic measurements of the interventricular septum, left ventricular posterior wall and left ventricular wall mass to electrocardiographic combinations used to predict left ventricular hypertrophy in both children and adults. The electrocardiographic correlations ranged from -0.01 to + 0.17. Poor correlations were found between electrocardiographic measures and blood pressure, left ventricular wall thickness or left ventricular wall mass. Skinfold thickness and weight had negative correlations, suggesting a damping effect upon measured voltage. We conclude that the echocardiogram is a more sensitive measurement of increased left ventricular mass than the ECG in children with elevated blood pressure.

Adolescent↗
PubMed1981

Effect of mitral valvular regurgitation on transthoracic impedance cardiogram.

Mitral valvular regurgitation consistently modified the wave form of the first derivative of the transthoracic impedance cardiogram. The transthoracic impedance cardiogram was recorded in 23 control subjects (group 1), and 23 patients with isolated mitral regurgitation (group 2). Simultaneous transthoracic impedance cardiogram, electrocardiogram, and mitral valve echocardiograms in group 1 showed that the primary diastolic wave ("O") of the transthoracic impedance cardiogram occurred synchronously with the maximal opening of the mitral valve. In group 2, the primary systolic wave (dZ/dt max) was diminished, and the "O" of the transthoracic impedance cardiogram was raised. The area under the systolic wave of the transthoracic impedance cardiogram (S) and the area under the diastolic opening of the transthoracic impedance cardiogram (D) were measured and the ratio D/(D + S) calculated. This ratio, called the mitral regurgitation fraction was (0.50 +/- 0.14) in group 2 which was higher than that found in group 1 control subjects (0.11 +/- 0.08). The mitral regurgitation fraction (15 to 77%) determined by the impedance method was closely correlated with the mitral regurgitation fraction (20 to 74%) obtained during cardiac catheterisation; it also increased during isometric handgrip and decreased during amyl nitrite inhalation. In three mitral regurgitation patients the transthoracic impedance cardiogram returned to normal configuration after surgical implantation of a prosthetic mitral valve. These data suggest that the transthoracic impedance cardiogram is quantitatively altered in patients with mitral regurgitation.

Adolescent↗
PubMed1980

Cardiac function in primary hypothyroidism.

Cardiac chamber dimensions and myocardial function were studied in 15 children with primary hypothyroidism prior to and after thyroxine therapy. Small pericardial effusions were detected in 11 of 15 subjects before therapy, which resolved in nine of 11 subjects after initiation of thyroxine replacement. There was no association between the severity of the thyroid failure and the presence of effusion, and no evidence of cardiac compromise due to effusions. No significant abnormality in cardiac chamber or myocardial dimensions, systolic time intervals, or indices of myocardial contractility was detected among the hypothyroid children as compared with a normal population. Neither myocardial dimensions nor contractility indices changed significantly on reestablishment of normal thyroxine concentrations with exogenous hormone. These data refute the existence of a myocardiopathy associated with hypothyroidism in children.

Adolescent↗
PubMed1980

Endocarditis in the newborn.

Three cases of endocarditis confirmed at autopsy were identified in an intensive care nursery during an eight-month period. Echocardiography demonstrated abnormal echoes in the region of the mitral valve in one infant and the tricuspid valve in the other two infants. Both the diverse clinical manifestations of bacterial and nonbacterial endocarditis and the value of echocardiography in the establishment of an antemortem diagnosis are discussed. This previously unusual entity seems to be occurring with greater frequency in neonatal intensive care units that provide vigorous efforts to support severely ill infants.

Autopsy↗
PubMed1980

The effect of acute aortic regurgitation on the transthoracic impedance cardiogram.

In nine anesthetized dogs, recordings of the first derivative of the transthoracic impedance cardiogram (ICG) were made during varying grades of acute aortic regurgitation. Acute aortic regurgitation was induced using a specially designed umbrella catheter, passed retrograde across the aortic valve into the left ventricle. The RFA (representing the fraction of the aortic reverse flow to the aortic forward flow) was computed using an electromagnetic flow probe implanted around the ascending aorta. Both the peak of the scalar ICG, dz/dtmax, which occurs at peak systolic ejection, and the nadir of the scalar ICG, X, which marks the closing of the aortic valve, increased with aortic regurgitation. The planimetered areas of the ICG during systole (S), and in early-diastole (X) increased during aortic regurgitation. These areas, S and X, correlated with the electromagnetic normalized aortic stroke volume (r = 0.90) and the regurgitant volume (r = 0.78), respectively. The ICG ratio X/S was correlated directly with the electromagnetic aortic regurgitant fraction (r = 0.86). This study demonstrates that the ICG waveform is consistently modified by experimental aortic regurgitation. Furthermore, these changes can be quantitatively related to the degree of aortic regurgitation.

Animals↗
PubMed1980

Hypoplastic left heart syndrome: successful palliation with a new operation.

A new operative procedure is described for the palliation of hypoplastic left heart syndrome. The operation consists of anastomosis of a tubular prosthesis between the proximal pulmonary artery and the aortic arch. A calibrated opening in the graft is brought into continuity with the distal pulmonary artery to provide balanced pulmonary and systemic blood flow. The atrial septum is excised and the ductus arteriosus ligated. A successful case report documents that this operation satisfies criteria required to reverse heart failure in infants with hypoplastic left heart syndrome.

Aorta, Thoracic↗
PubMed1979

Cardiac rhabdomyoma simulating pulmonic stenosis.

The angiographic and echocardiographic findings of a right ventricular pedunculated rhabdomyoma prolapsing through the pulmonic valve which mimicked the hypoxic spells of tetralogy of Fallot are presented. A dense mass of echoes was seen within the pulmonic valve during systole. The presence of right ventricular tumor was confirmed by angiography and surgery. The abnormal echoes were no longer seen following surgical excision of the tumor.

Cineangiography↗
PubMed1979

Measurement criteria for group echocardiographic studies.

This study reports the reproducibility achieved both within an observer and between observers measuring left heart echocardiographic dimensions using standard measurement criteria in school age children. These criteria define acceptable interfaces as: 1) a single dominant line; 2) continuity at the point of measurement of at least 5 mm in length; and 3) display of specific motion characteristics for the cardiac structure to be measured. The within observer intraclass correlation coefficient for interventricular septum, diastolic dimension, systolic dimension, left ventricular posterior wall, left atrium and aorta averaged 0.94 (range 0.87--0.98). The coefficient of variation averaged 3.6% (range 2--7.5%). The least reproducible dimension was left ventricular posterior wall. The day-to-day variability within a single subject of echocardiographic determined cardiac dimensions was small for all measurements. The standard deviation of error for all variables was no more than 0.3 mm. A system using screening criteria and standardized measurement techniques can provide the degree of precision necessary to begin investigating echocardiographic differences in group studies.

Adolescent↗
PubMed1979

Septation of the univentricular heart. Transatrial approach.

The technique of septation of the univentricular heart via a transatrial approach is described in detail. Clinical details of four patients having Type A-III univentricular heart document the feasibility of working through the right-sided atrioventricular valve to place a cloth prosthesis into the ventricle to divide it into approximately equal chambers. Improved hemodynamics were observed in the postoperative period, which probably were related to retaining the integrity of the ventricular wall. This approach seems best suited to the ventricular chamber estimated to be large by echocardiography without severe pulmonary outflow tract obstruction. Techniques for enlargement of the pulmonary outflow tract are also described.

Adolescent↗