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Biomedical subjects

R M Lauer

Publications and source records attributed to R M Lauer.

At least 109 records · Page 6Linked 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↗
PubMed1978

Blood pressure and its significance in childhood.

Hypertension is an important accelerator of the atherosclerotic process. Detection in childhood may be important although longitudinal data are lacking of the prognosis of blood pressure measurement in childhood through adult life. The blood pressure of children should be measured. In populations where salt intake is high, values for blood pressure increase with age. Populations who eat small quantities of salt are relatively free from hypertension. There is an epidemiological argument for limiting salt intake in children. There are few data to indicate the level of blood pressure in children which should be treated. Children's blood pressures are labile and elevated levels are sustained only in a small minority. In these secondary causes, advice should be sought. In subjects with extreme persistent hypertension drug therapy should be considered; in subjects with values of blood pressure not so extremely raised surveillance should be maintained to prevent the development of sustained hypertension.

Adolescent↗
PubMed1978

Tracking of blood lipids and blood pressures in school age children: the Muscatine study.

In four cross sectional school screens, the Muscatine Study has sampled 8,909 school children; 820 have been studied repeatedly over a six-year period. Tracking of measurements described by the relationship between repeated observations and the relationship between peer rank orderings over the six-year period has been studied. For height and weight, correlations between observations six years apart were approximately 0.74 and about 60% of children initially in the upper quintile were there again six years later. Six-year correlations were 0.65 for skinfold and 0.61 for cholesterol. Four-year correlation for fasting triglyceride was 0.40. Six-year correlations were 0.30 for casual systolic blood pressure and 0.18 for diastolic blood pressure. Peer rank orderings for both blood pressures were highly variable. Height and weight track well, and thus routine measurement of these variables are useful in identifying children with growth perturbing disorders. Cholesterol and, to a lesser degree, triglycerides also track, and a significant proportion of children with initially high values demonstrated consistently high values throughout the study period. Blood pressures do not track as well; consistently high blood pressures are unusual, thus indicating the need for repeated blood pressure measurements to identify children with persistent elevated levels. The future significance of transient blood pressure elevations has yet to be established.

Adolescent↗
PubMed1978

Normal blood pressure and the evaluation of sustained blood pressure elevation in childhood: the Muscatine study.

This study describes the seated blood pressure distributions of 6,622 predominantly white schoolchildren in Muscatine, Iowa. Subjects with seated pressures equal to or greater than the 95th percentile for age and sex or 140 mm Hg systolic or 90 mm Hg diastolic were examined on repeated occasions. Approximately 13% of subjects were found to have blood pressures at these levels when first examined, but less than 1% were found to have persistent blood pressure elevations. Of 41 subjects found to have persistent blood pressure elevations, 23 were obese with relative weights in excess of 120%. Of the 18 lean subjects, 5 had secondary hypertension and 13 were considered to have essential hypertension. Mass screening of school-age children identifies many children with transient elevation of blood pressure and few with fixed high blood pressures. Children's blood pressures should be assessed during their continuing care where pressures can be measured over a period of time to identify those with fixed blood pressure elevations.

Adolescent↗
PubMed1978

Value and safety of diet modification to control hyperlipidemia in childhood and adolescence. A statement for physicians. Ad Hoc Committee of the Steering Committee for Medical and Community Program of the American Heart Association.

Hyperlipidemia clearly is a risk factor for atherosclerotic disease in adults and very likely contributes to atherogenesis in children. The American Heart Association recommends that children with elevated plasma cholesterol or triglyceride be placed on an appropriate diet in order to reduce their risk of hyperlipidemia and possibly to reduce their risk of atherosclerotic disease when they become adults. Although the evidence does not yet support the recommendation that cholesterol and saturated fat should be reduced in the diet of all children, the public should be advised that such modification appears safe and very likely to be beneficial. Measuring plasma lipids of all children in order to prevent atherosclerotic disease probably is not cost effective. However, children of high risk families should be examined for hyperlipidemia.

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

Blood pressure, salt preference, salt threshold, and relative weight.

This study was performed to observe the relationships of salt preference, salt threshold, the relative weight to blood pressure. Three groups were selected from 4,800 school children on the basis of mean blood pressure: less than or equal to fifth percentile, in the area of the 50th percentile, and greater than or equal to 95th percentile. Salt threshold was determined by titrating, on each subject's tongue, solutions ranging from 1 to 60 millimols/liter of sodium chloride. Salt preference was tested by the addition of salt by each subject to unsalted tomato juice and beef broth according to individual taste. The samples were then analyzed for sodium concentration. The coefficient of correlation for the amount of salt added to juice and broth was significant (r=0.63). There was no relationship of salt threshold to preference, nor did threshold or preference relate to blood pressure. Relative weight was related to blood pressure range being the most obese.

Adolescent↗
PubMed1976

Hemodynamic effects of vasodilator agents in dogs with experimental ventricular septal defects.

The ratio of pulmonary to systemic vascular resistance (Rp/Rs) largely determines the amount of left-to-right shunting and pulmonary to systemic flow rat (Qp/Qs) in the presence of a large isolated ventricular septal defect. The possibility that pharmacologic reduction of systemic vascular resistance with alpha-adrenergic receptor blockade or beta-adrenergic receptor stimulation would increase the ratio Rp/Rs, and therefore reduce the ratio Qp/Qs, was studied in dogs in which ventricular septal defects had been surgically created. Administration of phentolamine and phenoxybenzamine caused a 42% reduction in Rs and no reduction in Rp. Qs was unchanged and Qp declined by 24% and the ratio Qp/Qs fell by 32%. Infusion of the beta-adrenergic receptor stimulant isoproterenol also reduced Qp/Qs. However, this was accomplished as a result of an increase in Qs and at the expense of an increase in heart rate. As a decline in the ratio Qp/Qs has been shown to be beneficial to patients with large left-to-right shunts, pharmacologic reduction of systemic vascular resistance may prove to be helpful in treating congestive heart failure in those patients with large left-to-right shunts at the ventricular level who are refractory to the usual decongestive measures.

Animals↗
PubMed1976

Patent ductus arteriosus in premature infants. Indications for surgery.

In order to establish more objective criteria for surgical intervention, the literature and our clinical experience with operative closure of patent ductus arteriosus in 11 premature infants was reviewed. A wide range of age at the time of operation underscored the spectrum of clinical presentation and the difficulty of interpreting the course of therapy. The presence of a typical continuous murmur established the diagnosis of patent ductus arteriosus in patients with respiratory distress syndrome. Cardiac catheterization confirmed the diagnosis and provided quantitation of the left-to-right shunt flow through the ductus arteriosus in 6 patients but did not influence the decision to operate. Progress of the clinical course as determined by the heart size on chest roentgenogram and the presence of hypercarbia (Paco2greater than60 mm. Hg) after respiratory assistance and medical decongestive measures were the two most helpful signs indicating the need for surgical intervention.

Cardiac Catheterization↗
PubMed1976

Anomalous origin of the left coronary artery from the right pulmonary artery.

A previously unknown coronary artery anomaly is reported: origin of the left coronary artery from the right pulmonary artery. This unusual anomaly can probably be explained by the theory of dual embryonic development of the coronary arteries from angioblastic buds in the truncus arteriosus. It is thought that these buds anastomose with a capillary network that is developing on the surface of the ventricles. Complete repair of this lesion with restoration of a two-coronary artery system was accomplished in a 10-month-old baby. The coronary artery was detached from the pulmonary artery, with a button of pulmonary artery being retained around the coronary artery ostium. Direct systemic arterial flow to the left coronary artery was established by anastomosis of the left coronary to the right subclavian artery.

Coronary Vessel Anomalies↗
PubMed1975

Echocardiographic findings in right coronary arterial-right ventricular fistula. Report of a neonate with fatal congestive heart failure.

Coronary arteriovenous fistula is a rare cause of congestive heart failure in the newborn. We describe a 2 day old infant with a large fistula between the right coronary artery and right ventricle that caused fatal congestive heart failure. An echocardiographic study revealed a large right ventricle, paradoxical motion of the interventicular septum and an enlarged aorta, suggesting an unusual location of a left to right shunt. The diagnosis was established at cardiac catheterization when a large left to right shunt was found at the ventricular level; the fistula was visualized by angiography.

Arteriovenous Malformations↗
PubMed1975

Congenital cardiac anomalies: one-stage repair in infancy.

A proposed preferred treatment plan consisting of one-stage operative repair of congenital cardiac anomalies whenever complete correction was feasible and operative intervention required was tested during the period February 1, 1972, to September 15, 1974. Experience with 74 patients aged 14 hours to 24 months allows some conclusions to be made regarding the advisability of this approach. For patients with ventricular defect and tetralogy of Fallot, this approach has quite acceptable results and certainly is more direct than palliative operations and second-stage repair. The hypothesis is more difficult to justify in patients with transposition of the great arteries. By avoiding repair in patients under 4 months of age and using a better technique for placement of the intraatrial partition, improved results are anticipated. In the miscellaneous group of anomalies, results depend upon the complexity of the defect and the ability to achieve accurate anatomical correction. After an early mortality of 20% and some late deaths, survival and improvement resulted in 51 of these babies. These results justify persistence in the choice of one-stage correction when operative intervention is required.

Child, Preschool↗