Search PubMed⌕ Search

Biomedical subjects

H D Allen

Publications and source records attributed to H D Allen.

At least 145 records · Page 8Linked to original sources
PubMed1980

Qualitative real-time cross-sectional echocardiographic imaging of the human fetus during the second half of pregnancy.

In this study, we used high-resolution echocardiographic systems to investigate how early in pregnancy normal fetal cardiac anatomy could be noninvasively evaluated. Over a 2-year period, 84 of 88 fetuses were successfully imaged (27 were studied serially). Postnatal images of 73 were obtained during the newborn period. Estimated fetal age varied at initial examination from 19-41 weeks (mean +/- 0.5 weeks [+/- SEM]) of pregnancy. Estimated fetal weight using an ultrasound algorithm varied from 500-3100 g (mean 1580 +/- 80 g [+/- SEM]). To evaluate fetal cardiac anatomy, we reproduced commonly used cross-sectional views of the heart. The four-chamber and the short-axis great artery views have been most successful for cardiac evaluation in the fetus. These views could be obtained in 96% and 95% of the patients, respectively. With these views, cardiac chamber and valve structures, as well as two great arteries, could be imaged in detail. The ascending and descending aorta, as well as the aortic arch and vessels to the arms and head, were visualized in 87% of examinations, and the inferior and superior venae cavae were visualized in 76%. In two of three RH fetuses, changes in cardiac chambers compatible with hydrops fetalis were demonstrated. We examined all fetuses after birth and verified clinically (or noninvasively) that no cardiac malformations were present. It appears, however, that the diagnosis of major congenital heart defects should be possible before birth.

Aorta↗
PubMed1980

Echocardiographic determination of contraction and relaxation measurements of the left ventricular wall in normal subjects and patients with muscular dystrophy.

Boys with Duchenne's muscular dystrophy (DMD) usually have a cardiomyopathy characterized by fibrosis of the epicardial half of the left ventricle. This cardiomyopathy is difficult to detect by noninvasive techniques. We report a technique that evaluates incremental left ventricular posterior wall thickening and thinning. High-quality left ventricular posterior wall echoes in 24 boys with DMD and 32 controls were recorded at chordal level two times 1 year apart. Endocardial and epicardial echoes and a timing ECG were digitized and analyzed by minicomputer. Left ventricular wall amplitudes were determined at standardized temporal increments during contraction and relaxation. To compare with this left ventricular assessment technique, systolic ejection times, shortening fraction and mean velocity of circumferenial fiber shortening (Vcf) were also computed in the standard way. Mean year-to-year changes were minor. Mean Vcf, the ratio of preejection period to left ventricular ejection time and shortening fraction during the first year were statistically similar to those of the controls. Shortening fraction decreased slightly during the second year and became significantly different from the control, but remained within the normal range. Left ventricular wall thickness and cavity size were significantly less in boys with DMD than in controls. Therefore, we had to normalize incremental wall thickness to determine if any significant difference occurred. To do this, we evaluated the percentage of maximal wall thickness which occurred at a given percent of systole and diastole. Using this technique, it was shown that thickening during systole was a nearly linear process with respect to time in both groups. However, relaxation was significantly different between the groups. Relaxation was found to be an alinear process, and most thinning occurred in the first 40% of diastole. The major findings of this investigation was that the left ventricular wall of boys with DMD thinned at a slower rate than that of normal subjects. This new technique appears to be sensitive and demonstrates subtle changes in the left ventricular posterior wall.

Adolescent↗
PubMed1979

Noninvasive assessment of surgical systemic to pulmonary artery shunts by range-gated pulsed Doppler echocardiography.

Suprasternal range-gated pulsed Doppler echocardiography was used to evaluate surgical shunt patency in children with cyanotic congenital heart disease and right ventricular outflow obstruction following systemic artery to pulmonary artery anastomoses. Normal patients had laminar Doppler auditory signals and time interval histogram flow patterns because right pulmonary artery turbulence was not present during systole or diastole. Patients with pulmonary valvar stenosis had turbulence during systole only. In all nine postoperative patients with surgical shunts, turbulent systolic and diastolic time interval histograms and abnormal auditory signals were present. A typical shunt murmur was not audible to auscultation in six of the postsurgical patients at the time of the study. Suprasternal range-gated pulsed Doppler echocardiography affords an accurate, safe and simple noninvasive bedside means for confirming shunt patency in patients who have undergone surgical systemic artery to pulmonary artery anastomoses.

Adolescent↗
PubMed1979

Subxiphoid cross-sectional echocardiography in infants and children with congenital heart disease.

We developed anatomically related cross-sectional echocardiographic views to image the heart from the subxiphoid area in 100 children and infants with various forms of congenital heart disease studied prospectively before cardiac catheterization. Wide-angle cross-sectional views were achieved using a mechanical sector scanner in a scan plane oriented parallel to a line between the patient's shoulders (a coronal plane) showing the equivalent anatomy of an anteroposterior angiogram. The subxiphoid technique appeared to be better than chest wall-based imaging in demonstrating obstructive lesions in the proximal portion of the right ventricular outflow tract (19 patients), i.e., the subpulmonic area, which is often at the narrow edge of the sector and behind the transducer artifact in chest wall studies. The subxiphoid technique was also useful for imaging the interatrial and interventricular septae; in subxiphoid views, as opposed to four-chamber apical views, there was significantly less false septal dropout and atrial septal defects (19 patients) as well as ventricular septal aneurysms (seven patients) were easily imaged. Finally, the subxiphoid orientation provided more adequate imaging in patients with discrete diaphragmatic subaortic stenosis (four patients), even when the diaphragm was just beneath the aortic valve. Subxiphoid cross-sectional echocardiography is an easily understood anatomical format for imaging cross-sectional anatomy in congenital heart disease and is a valuable adjunct to cross-sectional echocardiography from the chest wall.

Child, Preschool↗
PubMed1979

Echocardiographic profiles of the long-term cardiac changes in cystic fibrosis.

In this echocardiographic study, assessment of the heart in children with cystic fibrosis has shown that changes occur in not only the right ventricle but also in the left ventricle and aorta, as compared with normal. Echocardiograms could be successfully performed in 34 of 37 patients. The thickness of the right ventricular anterior wall and the dimension of the right ventricular cavity were abnormal, even in patients with mild disease (National Institutes of Health [NIH] score for severity of disease of 85 or greater). Larger, older children with lower NIH score had disproportionately larger right ventricular anterior walls and cavities. The thickness of the septal wall, the thickness of the left ventricular posterior wall, and the aortic dimensions were increased in those with severe disease. The dimensions of the left ventricular cavity for the population were slightly but significantly smaller than normal in systole and in diastole throughout the course of the disease. This study demonstrates that echocardiography is an effective noninvasive means of assessing the long-term changes in children with cystic fibrosis. These changes occur in both sides of the heart and appear to worsen as the disease progresses.

Adolescent↗
PubMed1979

A rational approach to ligation of patent ductus arteriosus in the neonate.

During a 23-month period, 25 premature infants underwent ligation of a patent ductus arteriosus performed in the neonatal intensive care unit utilizing a limited posterolateral muscle-retracting incision. This approach afforded adequate exposure with minimal surgical time and trauma. All infants manifested severe respiratory distress and congestive heart failure. Both standard and contrast echocardiographic studies were used for noninvasive preoperative evaluation. Echocardiographic study proved to be a highly reliable and sensitive indicator of ductal patency. Eight infants (32 percent) died at 8 to 225 days of age. The primary cause of death was progressive pulmonary disease with subsequent failure of multiple organ systems. Seventeen (68 percent) of the 25 infants survived to leave the hospital. Advantages of ligation of a patent ductus arteriosus in the neonatal intensive care unit include the elimination of problems of transportation (thermoregulation, ventilation, and loss of lines) and continuity of ongoing care and monitoring. The standard facilities of the neonatal intensive care unit proved completely satisfactory for ligation of a patent ductus arteriosus. Ligation in the neonatal intensive care unit is suggested to minimize potential complications of care in the operating room and transport of these critically ill infants.

Ductus Arteriosus, Patent↗
PubMed1979

[The usefulness of range-gated pulsed Doppler echocardiography. A review (author's transl)].

Single-crystal RGPD Echocardiography has clearly become a useful noninvasive ultrasonic method which enlarges the capabilities of investigating the heart. Recording of flow direction and showing disturbed flow allows additional clarification and confirmation of various diagnoses. This single-crystal technique does not allow flow quantification at the present time. The TIH and auditory signal displays of Doppler shift as presently utilized in commercial devices allow qualitative observation but require much experience in test performance and evaluation. The future here is probably in the area of spectral analysis. Present instrumentation employs M-mode echo for Doppler sample localization. Drawbacks include inprecise sample beam localization and non-variable sample volume size. Further, standardization of the Doppler signal is necessary. Combination with 2-D echo in the future will allow more precise sample beam localization and accuracy in flow quantification. The latter area has particular promise and is under investigation but is not yet commercially available.

Aortic Coarctation↗
PubMed1978

Real-time cross-sectional echocardiographic imaging and measurement of the patent ductus arteriosus in infants and children.

While echocardiography has been used to noninvasively document indirect effects on the heart of left-to-right shunting through a patent ductus arteriosus, no noninvasive technique has been developed to image the duct itself. In this study, 35 sequential studies were performed on 28 patients with a mechanical sector scanner to image the distal pulmonary artery and its bifurcation by scanning along the axis of the right ventricular outflow tract. Cross-sectional imaging, just superior to the take-off of the right pulmonary artery, provided visualization of the patent ductus as a distal continuation of the pulmonary artery connecting to the descending aorta. Ductal visualization by cross-sectional echo was validated by saline echo contrast observations of right-to-left and left-to-right shunting through the duct in 14 patients, by surgical observations in 11, angiographic observations in 13 and autopsy observations in three. Angiographic size of the ductus arteriosus, whether constricted or widely patent, tortuous or straight, was predicted correctly and echo/angiographic correlations for smallest inner ductal dimension were excellent (r = 0.97). This study provides a method for and validates the direct imaging of the ductus arteriosus and suggests that cross-sectional echocardiography can accurately predict ductal contour and quantitative ductal cross-sectional size noninvasively.

Adolescent↗
PubMed1978

Echocardiographic diagnosis of atrial septal aneurysm in an infant with hypoplastic right heart syndrome.

Echocardiographic findings are described in a patient with hypoplastic right heart syndrome (pulmonary atresia type with intact ventricular septum and small right ventricular cavity) who had an associated atrial septal aneurysm. An unusual appearance of echoes behind the aorta bulging into the left atrium in diastole on both the M-mode and cross-sectional echo suggested this diagnosis prior to cardiac catheterization. The angiographic findings confirmed the diagnosis of right ventricular hypoplasia, pulmonary atresia and the large atrial septal aneurysm. The infant died after surgery and the atrial septal aneurysm was observed at autopsy. The importance of the diagnosis of the atrial septal aneurysm and its association with restriction of right-to-left atrial shunting prompts this report.

Cardiac Catheterization↗