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Biomedical subjects

R M Schieken

Publications and source records attributed to R M Schieken.

72 records · Page 4Linked to original sources
PubMed1978

Effect of aortic valvular regurgitation upon the impedance cardiogram.

The first derivative thoracic impedance cardiogram, phonocardiogram, and electrocardiogram were recorded in three groups of 22 subjects each. In Group 1 (control), simultaneous impedance cardiogram, phonocardiogram, and aortic valve echocardiograms showed that the X point of the impedance cardiogram occurred synchronously with the aortic second heart sound and with echocardiographic aortic valve closure. In group 2 (clinical diagnosis of aortic regurgitation) the scalar magnitude of the impedance cardiogram O wave and the ratios of the impedance cardiogram wave form X/dz/dtmax and O/dz/dtmax were different from control. In addition, the early diastolic (X) and systolic portions (S) of the impedance cardiogram wave form of group 3 patients were planimetered and expressed as the ratio X/S, called the impedance cardiographic aortic regurgitant fraction (aortic RFI). The aortic RFI was increased by handgrip, a manoeuvre which acutely increases the magnitude of aortic regurgitation. The difference between Fick cardiac output and left ventricular angiographic output was used to calculate aortic valvular regurgitant fraction, which related closely to the impedance cardiogram. These data suggest that it is useful in the noninvasive assessment of aortic regurgitation.

Adolescent↗
PubMed1977

A simplified method of echocardiographic data analysis.

Rapid accurate analysis of echocardiographic data is accomplished using a sonic digitizer and programmable calculator. This method allows the echocardiographer to select technically optimal areas of the recording for analysis. The resolution of the measuring device is 0.1 mm. A hardcopy printout of both measurement and calculation is provided. Instead of expensive on-line computer, an inexpensive programmable calculator is used.

Computers↗
PubMed1976

Echocardiographic abnormalities in acute rheumatic fever.

The echocardiographic velocity of circumferential fiber shortening and left atrial dimension were measured serially in two groups of children with acute rheumatic fever: Group I, six patients with valve regurgitation without congestive heart failure, and Group II, seven patients with regurgitation and congestive heart failure. In Group I, the initial velocity of circumferential fiber shortening was increased to 1.90 +/- 0.31 circumferences per second (circ/sec) (mean +/- standard deviation). In group II, it was decreased (1.18+/-0.25). In group I velocity of circumferential fiber shortening subsequently decreased but remained above the normal level; in Group II it increased to exceed the expected normal value. Concurrent changes in left atrial dimension were observed in both groups. The initial left atrial dimension of Group I (2.2 +/- 0.75 cm/m2) was slightly increased and returned to normal (1.70 +/- 0.32) on follow-up study. The left atrial dimension of Group II was greatly increased initially (2.70 +/- 0.81 cm/m2) and remained large (2.50 +/- 0.67). Three patients in Group II experienced rebound during corticosteroid withdrawal. In each the velocity of circumferential fiber shortening decreased, suggesting impaired cardiac contractility. The echocardiogram thus facilitates serial assessment of the severity of carditis in acute rheumatic fever.

Acute Disease↗
PubMed1975

Cardiac manifestations of the mucopolysaccharidoses.

The cardiovascular manifestations of the mucopolysaccharidoses (MPS) have not been well characterized. We studied nine children with various forms of MPS, using noninvasive cardiac diagnostic techniques. The echocardiograms of two brothers with Type I H/S MPS showed slow mitral valve early diastolic closure velocities (MVEDC) (18, 29 mm/sec) consistent with mitral stenosis. Each had a soft opening snap, low frequency presystolic murmurs and X-ray evidence of calcific mitral stenosis. Three patients with Type II A MPS had echocardiographic evidence of impaired left ventricular function, suggesting the presence of myocardial damage. One of these had an abnormal electrocardiogram; non had murmurs. No cardiac abnormalities were discovered in two patients with Type III A and IV MPS. One patient with Type VI A MPS had presystolic, holostolic and early diastolic murmurs. A soft opening snap was recorded. The echocardiogram showed a slow MVEDC (18 mm/sec) and a slightly enlarged left atrial dimension (2.2 cm/m2). In summary, noninvasive studies are useful in evaluating patients with MPS. Type I H/S and Type VI A patients may show evidence of valvular deformity, the former associated with mitral valvular calcification and the latter with both aortic and mitral valve involvement. Type II A patients have muscle function abnormalities and Type III A and IV are shown by noninvasive methods to be free of cardiovascular abnormalities.

Adolescent↗
PubMedDate not supplied

Autoregulation of cerebral blood flow in fetuses with congenital heart disease: the brain sparing effect.

Fetuses with congenital heart disease (CHD) have circulatory abnormalities that may compromise cerebral oxygen delivery. We believe that some CHD fetuses with decreased cerebral oxygen supply have autoregulation of blood flow that enhances cerebral perfusion (brain sparing). We hypothesize that cerebral autoregulation occurs in CHD fetuses, and the degree of autoregulation is dependent on the specific CHD and correlates with intrauterine head circumferences. CHD fetuses were compared to normal fetuses. Data included cardiac diagnosis, cerebral and umbilical artery Doppler, head circumference, weight, and gestational age. The cerebral-to-placental resistance ratio (CPR) was assessed as a measure of cerebral autoregulation. CPR = cerebral/umbilical resistance index (RI) and RI = systolic-diastolic/systolic velocity (normal CPR > 1). CPR > 1 was found in 95% of normal vs 44% of CHD fetuses. The incidence of CPR < 1 was greatest in hypoplastic left or right heart fetuses. Compared to normal, cerebral RI was decreased in CHD fetuses. The CPR vs gestational age relationship, and the relationship among weight, head circumference, and CPR differed across normal and CHD fetuses. Fetuses > 2 kg with CHD and a CPR < 1 had smaller head circumferences than normal. Brain sparing occurs in CHD fetuses. Fetuses with single ventricular physiology are most affected. Inadequate cerebral flow in CHD fetuses, despite autoregulation, may alter brain growth.

Blood Flow Velocity↗
PubMedDate not supplied

Hoarseness as the initial clinical presentation of anomalous left coronary artery from the pulmonary artery.

Anomalous origin of the left coronary artery from the pulmonary artery is a rare congenital anomaly that, if left untreated, will most often result in severe myocardial ischemia and significant morbidity and mortality. We report an unusual presentation of this defect in a 2-month-old infant who had an initial complaint of a "hoarse cry." We theorize that impingement of the recurrent laryngeal nerve due to dilatation of the pulmonary artery was the most likely etiology of the patient's symptoms. This case serves as an important reminder that serious congenital heart disease may present with any number of complaints and unusual findings.

Blood Vessel Prosthesis Implantation↗
PubMedDate not supplied

Genetic and environmental contributions to cholesterol and its subfractions in 11-year-old twins. The Medical College of Virginia Twin Study.

We conducted a cross-sectional analysis of the genetic and environmental contributions to the variance of lipoprotein cholesterol and its subfractions in children during early adolescence. Univariate path analysis was used to determine the relative contributions of genes, individual environment, and family environment to these measures in 233 11-year-old Caucasian twin pairs. For high density lipoprotein, high density lipoprotein2, low density lipoprotein, very low density lipoprotein, and triglycerides, a model that incorporated genes and individual environmental variation but not common environment was sufficient to explain the variation. Different magnitudes of genetic effects were seen for total cholesterol in boys and girls. High density lipoprotein3 showed different magnitudes by sex for genetic and individual environmental effect. Intermediate density lipoprotein was the only cholesterol subfraction in which shared, or common, environment was found to make a statistically significant contribution to the variation.

Algorithms↗
PubMedDate not supplied

Left ventricular hypertrophy in children with blood pressures in the upper quintile of the distribution. The Muscatine Study.

From echocardiography measurements of left heart dimensions, cardiac output was estimated in 264 school children whose systolic blood pressure persisted in the lowest, middle, or highest quintile of the distribution for their age and sex. Children with blood pressure in the upper quintile were taller, heavier, and more obese. Echocardiographically determined left ventricular wall mass, corrected for body size, was significantly greater in these children than those in the lower quintiles of blood pressure. These children displayed a continuum of cardiac output. Those with the highest cardiac output in the upper blood pressure quintile had the greatest left ventricular wall mass.

Adolescent↗
PubMedDate not supplied

The cardiovascular responses to exercise in children across the blood pressure distribution. The Muscatine study.

Children with elevated systolic blood pressure have a wide range of cardiac output. To better understand the mechanisms regulating resting and exercise blood pressure, we investigated the cardiovascular responses to both dynamic and isometric exercise 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 sought to identify patterns of response to exercise that correlated with both resting cardiac output and resting blood pressure. During isometric exercise, systolic pressure adjusted for age and body size increased in all groups. The low group's mean pressure remained significantly lower than the high group's pressure throughout the entire exercise period. Body size adjusted group systolic and diastolic blood pressure level differences exist 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 is 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 the 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.

Adolescent↗