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L A Latson

Publications and source records attributed to L A Latson.

68 records · Page 4Linked to original sources
PubMed1984

Two-dimensional echocardiographic assessment of pulmonary artery and aortic arch anatomy in cyanotic infants.

To determine the feasibility and accuracy of noninvasive assessment of pulmonary artery and aortic arch anatomy, a prospective two-dimensional echocardiographic evaluation was performed in 20 consecutive cyanotic infants before cardiac catheterization and angiography. The echocardiographic assessment was correct with the following frequency: detection of left aortic arch in 13 of 13 infants, detection of right aortic arch in 7 of 7, identification of patent ductus arteriosus in 13 of 13 (one false positive finding), identification of a right pulmonary artery in 20 of 20, identification of a left pulmonary artery in 19 of 20, identification of the confluence of the right and left pulmonary arteries in 19 of 20 and identification of a main pulmonary artery in 14 of 16 (two false positive diagnoses by echocardiography). Echocardiographic estimates of arterial diameters were slightly smaller than those obtained by angiography. Mean vessel size (echocardiographic/angiographic diameter) was as follows: transverse aortic arch 8.6/10.6 mm, main pulmonary artery 5.7/6.3 mm, right pulmonary artery 4.1/4.2 mm and left pulmonary artery 4.2/3.9 mm. It is concluded that although two-dimensional echocardiography tends to underestimate vessel size, the qualitative assessment is adequate for planning a systemic to pulmonary artery anastomosis in selected infants with cyanotic forms of congenital heart disease.

Aorta, Thoracic↗
PubMed1984

Two-dimensional echocardiographic assessment of the aorta in infants and children with congenital heart disease.

To determine the accuracy of two-dimensional echocardiography in the identification of congenital anomalies of the aorta, we compared two-dimensional echocardiographic with angiographic results in 261 consecutive infants and children with congenital heart disease (age 1 day to 20 years, mean 3.3 years). Two-dimensional echocardiography was performed and interpreted without knowledge of angiographic results. Complete visualization of the ascending and descending aorta and aortic arch branches was possible by two-dimensional echocardiographic examination in suprasternal, parasternal, and subcostal views of 255 patients (98%). Identification of the esophagus during swallowing aided the diagnosis of anatomic characteristics of aortic arch. One or more significant aortic arch anomalies were present on angiograms of 116 of 255 patients (46%) and were detected by two-dimensional echocardiography in 110 (sensitivity 95%, 99% specificity). Anomalies detected by two-dimensional echocardiography/angiography were ascending aorta hypoplasia in four/four, truncus arteriosus three/three, right aortic arch 31/31, anomalous subclavian artery 11/16, coarctation 27/29, and patent ductus arteriosus 53/57. We conclude that two-dimensional echocardiography can be used to determine the anatomy of the aorta in most infants and children. In selected patients, two-dimensional echocardiography may eliminate the need for angiographic examination before surgery for congenital heart disease.

Adolescent↗
PubMed1984

Echocardiography in the diagnosis and management of symptomatic aortic valve stenosis in infants.

Infants with severe aortic valve stenosis often are critically ill and require urgent surgical treatment. Currently, angiography is used at the time of cardiac catheterization to diagnose aortic valve stenosis. However, the use of this test may be hazardous in an unstable infant and may precipitate hemodynamic and clinical deterioration before surgery. Therefore, a noninvasive method of accurately making this diagnosis would be useful in that it would allow the risks of cardiac catheterization to be avoided. Between January 1982 and September 1983, 10 infants with critically severe aortic valve stenosis and intact ventricular septum were examined by echocardiography. There were no false-positive or negative results in this time period and several criteria for the noninvasive diagnosis of critical aortic valve stenosis were recognized. These included immobile aortic valve cusps and left ventricular hypertrophy with increased echo density of the left ventricular papillary muscles and mitral valve support apparatus. Patients without other aortic obstruction had poststenotic dilation of the ascending aorta, as evidenced by a ratio of the diameter of the ascending aorta to that of aortic valve anulus greater than 1.7. A disturbed Doppler velocity signal in the ascending aorta supported the presence of valvar stenosis. Nine patients underwent cardiac surgery and five survived. In five patients surgery was performed without angiographic examination. The correct diagnosis was made noninvasively in each, and four of the five patients survived surgery. Echocardiography was comparable to angiography in making the diagnosis and assessing the cardiovascular anatomic characteristics. Echocardiography could therefore replace angiography in selected infants with symptomatic aortic valve stenosis and should be routinely used in the evaluation of these patients.

Aortic Valve Stenosis↗
PubMed1984

A gamma camera for medical applications, using a multiwire proportional counter.

A multiwire proportional counter gamma camera, specifically designed for nuclear medicine applications, is portable and weighs less than 50 lb including shielding and collimator. The basic operating characteristics have been investigated with various radioactive sealed sources. The camera demonstrates a peak count rate of 850,000 cps, an intrinsic spatial resolution of 2.5 mm, and excellent image uniformity when used with x-ray sources in the range of 22-81 keV. Tests of the device with Ta-178--a very promising, short half-life (9.3 min), low-energy radionuclide--using 20 mCi injections provided images of quality comparable to those obtained from 15 mCi Tc-99m studies with conventional imaging devices. The camera used with Ta-178 offers particular promise in first-pass nuclear cardiology studies. Considerably improved study quality will likely result in this area because of the increased injectable dose levels offered by Ta-178 combined with the high-count rate capability and improved resolution.

Americium↗
PubMed1983

Atrioventricular valve abnormalities in infancy: two-dimensional echocardiographic and angiocardiographic comparison.

The results of two-dimensional echocardiography and biplane angiocardiography from 47 infants with congenital atrioventricular (AV) valve abnormalities were compared. Eleven patients had atresia of the right AV valve, 10 had atresia of the left AV valve, 4 had hypoplasia of the right AV valve and 5 had hypoplasia of the left AV valve. Twelve patients had endocardial cushion defect, three had single ventricle and two had straddling of the left AV valve. There was agreement between the two techniques as to the number of AV valves present in each patient. The echocardiographic estimate of valve anular diameter was below normal in seven of the eight patients thought to have a hypoplastic anulus by angiocardiography. In 10 of the 12 patients with endocardial cushion defect, there was agreement between the two techniques as to the presence or absence of atrial and ventricular septal defect. The chordal attachments of straddling valves were better visualized by echocardiography; flow patterns and effective orifice size were better demonstrated by angiocardiography. The subcostal four chamber echocardiographic views and cranially angulated oblique angiocardiographic views were comparable and provided the best images for determination of the size and number of AV valves and their relation to the atrial and ventricular septa.

Angiocardiography↗
PubMed1983

Doppler measurement of myocardial thickening with a single epicardial transducer.

To eliminate the need for intramyocardial transducers in measuring regional left ventricular (LV) function we have developed a pulsed Doppler technique utilizing a single epicardial transducer. Wall thickening is evaluated by digitally integrating the velocity of myocardial layers passing through the sample volume located at a selected depth. Thickening fraction (TF) can then be estimated by dividing the systolic excursion by the sample volume depth. The Doppler method was compared with the transit-time method in three acute dogs by placing the 4-mm-diameter epicardial Doppler transducer over a 2-mm-diameter endocardial crystal tunneled through the LV wall. With the sample volume set to 1 mm less than the minimum LV thickness, simultaneous measurements of TF by the Doppler and transit-time methods showed good agreement (r = 0.95) during control, ischemia, volume overload, shock, and anoxia. In 28 chronically instrumented piglets signals were obtained for longer periods with Doppler transducers than with transit-time segment-length crystals. We conclude that the Doppler technique provides a high-fidelity wall thickening waveform and a good estimate of TF with minimal disturbance to the ventricle and that the technique is suitable for use in both acute and chronically instrumented animals.

Animals↗
PubMed1983

Hypertrophic obstructive cardiomyopathy: hemodynamic improvement with intravenous verapamil.

We report the reduction in left ventricular outflow tract gradient following the intravenous administration of verapamil to two pediatric patients with hypertrophic obstructive cardiomyopathy. Traditional therapy with beta adrenergic antagonists was relatively contraindicated in both patients. In a 15-year-old patient, the left ventricular outflow tract gradient decreased from 160 torr, at rest, to 45 torr during the verapamil infusion. In a 3-year-old boy, there was a reduction in the left ventricular outflow tract gradient from 60 torr, under basal conditions, to 10 torr during the intravenous verapamil infusion. We believe that verapamil may be effective in reducing the left ventricular outflow tract gradient in some pediatric patients with hypertrophic obstructive cardiomyopathy and may be useful in treating selected patients with this disorder.

Journal Article↗
PubMed1982

Echocardiographic pulsed Doppler features of absent pulmonary valve syndrome in the neonate.

M mode echocardiography was used to evaluate nine neonates with absent pulmonary valve syndrome. Six were also studied with two dimensional echocardiography and two with pulsed Doppler echocardiography. M mode echocardiography demonstrated a large, overriding great artery and right ventricular dilation in all nine patients and abnormal septal motion in eight. Two dimensional echocardiography demonstrated aneurysmal dilation of the main pulmonary artery in all six patients studied. Pulsed Doppler echocardiography in the two infants studied demonstrated anterograde systolic and retrograde diastolic flow in the main pulmonary artery and right ventricular outflow tract. The echocardiographic features of absent pulmonary valve syndrome appear to be unique and allow the diagnosis to be made noninvasively, thus obviating or delaying the need for potentially high risk cardiac catheterization.

Aneurysm↗
PubMed1982

Long-term follow-up of patients with malformations for which definitive surgical repair has been available for 25 years or more.

The results of long-term follow-up studies of patients with five common congenital heart defects are reviewed. The lesions included are ventricular septal defect, atrial septal defect, patent ductus arteriosus, pulmonary stenosis and coarctation of the aorta. A definitive, rather than palliative, operation has been available for each of these lesions for more than 25 years. Therefore many patients who have undergone operation for one of these lesions are now reaching adulthood. Although most of these postoperative patients live a normal life, many have residuae or sequelae that require close observation or treatment. Other persistent abnormalities of the physical examination, electrocardiogram and chest radiogram are obvious but call for no precaution or treatment. We have drawn on our own experience and the published experience of others to identify those findings and historical factors that best reflect the long-term prognosis of these patients. In addition, recommendations concerning the need for continued prophylaxis against infective endocarditis, and the problems of insurability and employability of these postoperative patients are discussed.

Adult↗
PubMed1981

Ventricular septal defect in infancy: detection with two dimensional echocardiography.

To determine the sensitivity and specificity of two dimensional echocardiography in detecting ventricular septal defect two dimensional echocardiograms were performed on 53 infants under 1 year of age. The diagnosis of ventricular septal defect was confirmed by cardiac catheterization in 27 patients; an intact ventricular septum was confirmed by catheterization in 18 and clinically in 8. Using a 35 degree mechanical sector scanner with a 3.5 megahertz transducer, we imaged the ventricular septum in the long axis and in a four chamber view (apical or subcostal, or both). Images were recorded on videotape and reviewed independently by two observers unaware of the diagnosis. Interobserver agreement was 94 percent. Among the 27 patients with a ventricular septal defect, the lesion was correctly identified in 20 (74 percent) and was undetected in 7 (3 of whom had a defect less than 4 mm in diameter, as determined by angiography). No defect less than 4 mm in diameter was detected. Among the 26 patients with an intact septum, a defect was correctly excluded in 23 (88 percent); a false positive diagnosis was made in 3. The apical and subcostal views demonstrated the greatest number of defects (20 of 20), but also gave the highest number of false positive diagnoses (3 of 3). The long axis view was helpful when positive, but showed only 9 of 20 of the defects. In this study, two dimensional echocardiography detected approximately three fourths of ventricular septal defects large enough to warrant cardiac catheterization in the 1st year of life. False positive diagnoses were related to dropout of echoes in the membranous septum when imaged in the four chamber views.

Cardiac Catheterization↗
PubMed1981

Resolution and accuracy in two dimensional echocardiography.

The resolution and accuracy of commercially available two dimensional echocardiographic systems were tested by imaging two types of in vitro test objects. One consisted of a series of fine parallel threads spaced at known intervals and the other was a tissue phantom in which a series of holes of known size had been cut. The echocardiographic systems tested included a mechanical single element sector scanner, a three element rotary sector scanner and a phased array system. Azimuthal resolution, lateral resolution and accuracy of horizontal distance measurements were assessed at depths of 2 and 6 cm. For each system, azimuthal resolution was better than lateral resolution, especially when assessed with use of the parallel threads. When the tissue phantom was imaged, the best resolution (2 mm in azimuthal and lateral directions) was obtained with the highest frequency transducer tested (3.5 MHz). The apparent size of a tissue defect was sensitive to gain settings, especially at a depth of 2 cm with lower frequency transducers; at a depth of 6 cm, echographic measurements of defect size were accurate to within 2.5 mm. Recent applications of two dimensional echocardiography require near the apparent limits of current equipment. It is recommended that the highest frequency transducer and lowest possible gain settings be used in these situations.

Cardiomyopathies↗
PubMedDate not supplied

Per-catheter ASD closure.

Per-catheter devices for atrial septal defect (ASD) closure have been evolving since 1974. The four major devices available for use on a limited basis in early 1997 are reviewed. These include (in alphabetical order) the Angel Wing device, the ASDOS device, the Buttoned device, and the CardioSeal device (successor to the Clamshell). Sufficient data have been collected to indicate that transcatheter ASD closure is a viable alternative to surgery in selected patients. The advantages of the concept of per-catheter closure over surgical closure should lead to the continued development of devices and techniques for per-catheter treatment of ASD and other septal defects in the years to come.

Cardiac Catheterization↗