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Biomedical subjects

L A Latson

Publications and source records attributed to L A Latson.

At least 55 records · Page 3Linked to original sources
PubMed1989

Transcatheter closure of patent ductus arteriosus in pediatric patients.

A "double disk" occlusion device (Rashkind PDA occluder system) has been designed to allow transcatheter closure of patent ductus arteriosus (PDA). During a 3-year period, we examined 37 infants and children (not premature neonates) with PDA as their only significant cardiovascular defect. Seventy-eight percent of these patients were considered potential candidates for the use of the PDA occlusion device, and it was successfully placed in all but 2 of 27 patients who underwent cardiac catheterization (PDA too small in one and too large in one). Only one of the remaining 25 patients had a significant residual shunt after placement of the device, which therefore was removed in the catheterization laboratory before surgical ligation of the PDA. There was no clinical evidence of a residual PDA in any patient. The duration of hospitalization was less than 24 hours for each of the last 20 procedures. Echocardiography demonstrated return to normal chamber dimensions in all patients, but a tiny, clinically undetectable residual leak around the device was found in three patients by Doppler evaluation. The transcatheter procedure was preferred over surgery by more than 90% of families and can be completed with a much shorter hospitalization than surgical ligation. We conclude that transcatheter closure of patent ductus arteriosus is feasible in the majority of children with PDA.

Cardiac Catheterization↗
PubMed1989

Signal-averaged electrocardiography of the terminal QRS in healthy young adults.

Interpretation of signal-averaged electrocardiograms (SAECG) in the young could be of value in detecting those at risk for episodic ventricular tachycardia, but suffers from a lack of data in normal young people. The purpose of this study is to determine normal values for QRS duration and the duration and amplitude of terminal potentials on the SAECG in young adults. Thirty-two normal medical students were examined. With high pass filtering at 25 Hz, normal total QRS duration (QRS) varied as a function of sex and body size whereas low amplitude signal duration (LAS) did not. Ninety-five percent confidence limits are: QRS (male) 85-117 msec, QRS (female) 76-102 msec, and LAS 6-35 msec. Root mean square voltage of the terminal QRS showed a broad scatter, however none was less than 20 microvolts. High pass filtering at 40 Hz did not change the QRS duration, but resulted in significantly longer LAS duration and diminished RMS voltage. Because of the longer QRS and shorter LAS previously reported in the presence of right bundle branch block, the normal values reported here should not be applied in the presence of intraventricular conduction delay following surgical repair of congenital heart disease. They will, however, provide a basis for interpretation of SAECG in young adults with normal QRS duration.

Adult↗
PubMed1988

Regional pulmonary perfusion estimated by high-speed volume scanning CT.

Three pigs with surgically created aortopulmonary shunts and two pigs who had sham operation were scanned in a fast computed tomography (CT) scanner, the dynamic spatial reconstructor (DSR). Each pig was scanned during injection of a bolus of roentgen contrast medium in the right atrium and during injection into the left ventricle. In addition to these DSR scans, radiolabeled, 15-micron-diameter microspheres were injected into the right atrium and into the left ventricle. The quantitative distribution of roentgen contrast agent was used to estimate regional pulmonary blood flow independently from the right and left circulations using analysis of the indicator dilution curves derived from the DSR images (Y). These values were compared to the regional values of pulmonary perfusion based on the microsphere distribution (X). The correspondence between the two methods (for all pigs together) was Y = 0.83X + 0.52 with r = 0.964. The less than unity slope is attributed to the partial collapse of the lung at the time of sectioning (for counting of tissue radioactivities). As regional air content of the lung also was measured from the DSR images, these data support the contention that regional ventilation and perfusion can be estimated from a fast CT scan of the thoracic contents during the passage of a bolus of contrast medium.

Animals↗
PubMed1987

Dynamic three-dimensional anatomy of pulmonary arteries in pigs with aorto-to-pulmonary artery shunts.

Accurate quantitation of three-dimensional pulmonary arterial geometry is difficult in vivo by the usual clinical imaging techniques. We have used a fast, multislice, computed tomography (CT) scanner, the dynamic spatial reconstructor (DSR), to obtain such measurements. After one injection of contrast medium into the right atrium, all major pulmonary arteries were imaged in three dimensions at 60 per second intervals throughout several cardiac cycles. Computer-generated pseudothree-dimensional displays were generated to show the arteries from several views so that superposition of arteries could be avoided. Using this technique, we have quantitated pulmonary arterial geometry in five pigs, three of them with surgically created aortopulmonary shunt and two with sham shunts. Pulmonary arterial cross-sectional areas (CSA) along the length of the left and right pulmonary arteries as they course through the lower lobes of the lungs were measured at peak-systole and end-diastole. From these image data, the systolic to diastolic change in CSA was measured. The regression line relating the CSA at these two phases had slopes in the five pigs ranging from 0.41 to 0.85. The magnitude of this slope corresponded closely with pulmonary arterial pressure, which ranged from 20 to 92 mm Hg.

Animals↗
PubMed1986

Percutaneous cardiac catheterization via the internal jugular vein in infants and children.

Cardiac catheterization was performed via the internal jugular vein in 14 pediatric patients using a percutaneous sheath technique. Patients were 2 months to 16 years old and weighed 3.2-69 kg. We found that a low lateral approach for puncture of the vein was faster and more often successful than the high approach most often utilized in adult patients. No complications occurred in this series of patients. The internal jugular vein is a safe and reliable alternative to the femoral vein for cardiac catheterization if there is obstruction to the inferior vena cava or if it is desirable to leave an indwelling cardiac catheter.

Adolescent↗
PubMed1985

Accuracy of two-dimensional echocardiography in the diagnosis of congenital heart disease.

To assess the accuracy of 2-dimensional (2-D) echocardiography in the evaluation of cardiac anatomy in patients with congenital heart disease, 2-D echocardiograms were performed in 126 infants and children before cardiac catheterization and angiocardiography. The segmental echocardiographic analysis included determination of intracardiac, great artery, systemic venous and pulmonary venous anatomy. The 126 patients had 259 separate cardiovascular abnormalities, of which 226 (87%) were prospectively identified by 2-D echocardiography. There were 8 false-positive diagnoses. The most common lesions and the sensitivity and specificity of echocardiography were: patent ductus arteriosus, 41 patients (83% and 100%, respectively), ventricular septal defect, 35 patients (86% and 100%); atrial septal defect, 26 patients (85% and 99%); pulmonary valve stenosis, 25 patients (77% and 97%), transposition of the great arteries, 16 patients (100% and 100%); and total anomalous pulmonary venous connection, 14 patients (85% and 100%). Less common defects and their rate of detection included coarctation of the aorta, 10 of 12 patients; atrioventricular canal, 10 of 10 patients; tetralogy of Fallot, 10 of 10 patients; aortic valve stenosis 8 of 8 patients; right aortic arch, 8 of 8 patients; interrupted aortic arch, 4 of 4 patients; and unilateral pulmonary vein atresia, 0 of 1 patient. In 33 patients (26%), the errors in echocardiographic analysis were judged to have surgical importance. Most errors were the result of overlooking or misinterpreting data that had been appropriately recorded on videotape. Pulmonary valve stenosis and patent ductus arteriosus are the lesions most likely to be misdiagnosed by ultrasound studies relying on imaging alone.

Cardiac Catheterization↗
PubMed1985

Echocardiographic evaluation of infective endocarditis in children.

To determine the incidence and prognostic importance of the echocardiographic abnormalities associated with infective endocarditis, we reviewed these findings in 45 episodes occurring in 41 children and young adults. Thirty-three patients had congenital cardiac abnormalities, and eight patients had no previously known heart disease. Echocardiographic abnormalities were detected in 16 of the 45 episodes of endocarditis (36%). M-mode echocardiography revealed abnormalities in seven of the 35 episodes (20%) in which it was performed, and two-dimensional echocardiography revealed abnormalities in 16 of the 28 episodes (59%) in which it was used. The presence of echocardiographic abnormalities was unrelated to the causative organism and to the need for early operation.

Adolescent↗
PubMed1984

Atrioventricular valve anular diameter: two-dimensional echocardiographic-autopsy correlation.

To study the accuracy of 2-dimensional echocardiography (2-D echo) in estimating mitral and tricuspid anular diameter, 2-D echo estimates were compared with autopsy measurements of anular diameter in 21 children studied by echo within 30 days of death. The mitral anulus was measured from the left parasternal long axis view and the apical or subcostal 4-chamber image and the tricuspid anulus from the 4-chamber view. Comparable measurements were made from the autopsy specimen with calipers. The correlation coefficient for echocardiographic vs autopsy measurements was 0.79 (standard error of the estimate 2.8 mm) (mitral long axis r = 0.76, mitral 4-chamber r = 0.85, tricuspid 4-chamber r = 0.76). Echo measurements exceeded the corresponding autopsy measurements by an average of 17%; this was at least partially attributed to shrinkage of the specimen during fixation. Thus, 2-D echo may be used to provide a reasonable estimate of mitral and tricuspid anular diameter.

Adolescent↗
PubMed1984

Microcomputer analysis of indicator dilution curves to determine Qp/Qs.

We developed and tested, in an animal model, a method for collecting and analyzing indicator dilution curves to determine the pulmonary-to-systemic flow ratio (Qp/Qs) using a programmable microcomputer. Curves were digitized in real time by an analog to digital converter. A gamma variate curve fitting algorithm, similar to that used in nuclear cardiology, was used to determine the area under primary and recirculation portions of a single cardiogreen dye curve. A ratio of these areas was used as a measure of Qp/Qs. In an animal model simulating patent ductus arteriosus, there was close correlation of Qp/Qs measured by the Fick method and by the microcomputer method (computer Qp/Qs = 0.95 X Fick Qp/Qs + 0.22, R = 0.97, N = 14, SEE = 0.14). The computer method of measuring Qp/Qs is rapid, easily repeatable, and does not require catheter manipulation. Therefore, it may be particularly useful in the clinical cardiac catheterization laboratory for studying the effects of interventions on Qp/Qs.

Animals↗
PubMed1984

Improvement of left ventricular dysfunction after control of persistent tachycardia.

Five children are described who had persistent, chronic tachycardia and left ventricular dysfunction manifested by decreased left ventricular percent fractional shortening on echocardiogram (five patients) cardiomegaly on chest roentgenogram (three), ventricular or atrial hypertrophy on ECG (three), and symptoms of congestive heart failure (three). After antidysrhythmia therapy and control of the tachycardia, signs and symptoms of congestive heart failure resolved in two infants. Moreover, in each patient signs of cardiomegaly resolved on chest roentgenogram, hypertrophy resolved on ECG, and the fractional shortening improved to normal (mean 20.2% +/- 2.4% SEM before vs 36.2% +/- 2.4%, P = 0.02, after treatment). Evaluation in the child who has dilated cardiomyopathy should include assessment of heart rate and rhythm. Moreover, when persistent tachycardia is found in an asymptomatic child, evaluation of left ventricular function is indicated.

Adolescent↗