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Biomedical subjects

L D Allan

Publications and source records attributed to L D Allan.

105 records · Page 6Linked to original sources
PubMed1983

The feasibility of fetal echocardiography in the prediction of congenital heart disease.

The fetal heart has been studied echocardiographically in over 750 pregnancies between 16 weeks gestation and term. This has allowed description of normal fetal cardiac anatomy, the acquisition of measurement data for various cardiac structures and the detection of 16 cardiac malformations. In all the patients delivered so far and in which normality was predicted the neonatal heart was confirmed to be normal (640) except in 3 early cases where defects were overlooked. This promises to be a useful technique for the reliable prediction of structural cardiac anomaly prenatally.

Echocardiography↗
PubMed1983

Early detection of congenital heart disease in prenatal life.

The anatomy of the fetal heart can be well seen by real-time cross sectional ultrasonography between 16 weeks' gestation and term. Many major structural abnormalities can be excluded in early pregnancy even if only one section of the fetal heart is studied. We have accurately predicted structural cardiac malformation in nine cases in the mid-trimester of pregnancy. Five pregnancies were interrupted for extracardiac abnormalities. In two cases of severe cardiac abnormality termination of pregnancy was chosen by the parents. In the remaining pregnancies where an abnormality was predicted delivery took place in a centre equipped for immediate care of an affected infant. This gave the infant the optimum chance of survival.

Female↗
PubMed1982

Balloon atrial septostomy under two dimensional echocardiographic control.

Two dimensional echocardiography has been used to guide balloon atrial septostomy in five cases of transposition of the great arteries. A single lumen balloon catheter was used. The catheter can be accurately located within the left atrium before inflation of the balloon, thus avoiding some of the traumatic accidents possible during septostomy. The balloon can be observed creating the atrial defect and the approximate size of the resulting defect noted. It can also be seen if the foramen ovale is only being stretched and not torn. The use of the two dimensional echocardiogram during septostomy should significantly contribute to the speed, efficiency, and safety of the procedure.

Echocardiography↗
PubMed1982

M-mode echocardiography in the developing human fetus.

The M-mode echocardiogram can be obtained in the developing human fetus from around the 16th week of gestation until term. Errors in interpretation of the M-mode echocardiogram can be avoided by concurrent two dimensional fetal cardiac examination. The pattern of motion of the mitral, tricuspid, aortic, and pulmonary valves and ventricular wall motion can be studied. Motion of the foramen ovale flap, which is characteristic in fetal life, can also be observed. Using the M-mode tracing, measurement data for six variables were made and growth charts constructed. The variables recorded were septal and left ventricular wall thickness, right and left ventricular internal dimension in diastole, aortic root dimension, and left atrial internal dimension. The measurements were made in normal pregnancies where the fetal heart was structurally normal. Confidence limits for each measurement were derived for gestational ages between 16 and 39 weeks.

Aorta↗
PubMed1981

Normal fetal cardiac anatomy--a basis for the echocardiographic detection of abnormalities.

Real-time examination of the fetal heart in 350 pregnancies has allowed a composite picture of normal fetal cardiac anatomy to be established and echocardiographic interpretation has been confirmed by anatomical studies. Two echocardiographic sections are readily obtainable and are suggested as applicable to routine scanning but the specialist nature of interpreting abnormalities is stressed. Six abnormalities have been suspected during the study and five confirmed anatomically or at cardiac catheterization. In view of the low incidence of congenital heart disease in a normal obstetric population, high risk groups should perhaps be selected for cardiac scanning at the present time. These include mothers of previously affected babies, diabetic mothers and certain abnormalities of pregnancy. Fetal ascites is particularly important, being present in three of four proven cases of cardiac abnormality.

Ascites↗
PubMed1981

Identification of congenital cardiac malformations by echocardiography in midtrimester fetus.

Fetal echocardiograms were performed in 21 pregnancies before midtrimester termination. All fetal heart specimens were collected and studied morphologically. Eighteen had been diagnosed as normal echocardiographically and this was confirmed anatomically. Deficiency of the atrial septum was suspected in one, and primum and secundum atrial septal defects were found anatomically. Coarctation of the aorta was suspected in another and this was confirmed anatomically. A ventricular septal defect was suspected in one which proved to be normal on dissection.

Echocardiography↗
PubMed1980

Echocardiographic and anatomical correlates in the fetus.

Fetal cardiac anatomy was studied in 200 pregnancies between 14 weeks' gestation and term using real time two-dimensional echocardiography. Eight scan planes were chosen as contributing valuable and distinct information on the establishment of cardiac normality. To confirm the echocardiographic interpretation, 25 fetal specimens between 12 and 28 weeks' gestational age were sectioned to imitate echocardiographic scan planes and the echocardiographic and anatomical pictures obtained were correlated with each other. The number of patients in whom each plane was recognized was tabulated in the first and second hundred, the second hundred having been studied after the anatomical studies were made. One longitudinal and one transverse plane could be seen in nearly all patients and considerable improvement in the frequency of recognition of other planes was made in the second hundred patients with increasing experience and anatomical understanding. The tricuspid-pulmonary and four-chamber planes alone, however, showed four cardiac chambers, two atrioventricular valves, and two arterial valves within their respective outflow tracts.

Echocardiography↗
PubMedDate not supplied

Outcome of prenatally diagnosed congenital heart disease: an update.

The objective of this study was to compare the outcome of prenatally diagnosed congenital heart disease (CHD) in a recent time period with previously reported experience. All cases of fetal CHD during the time period 1993 to 1999 were analyzed in terms of their outcome. During this time frame, 408 cases of fetal CHD were detected. Of these, 84% of mothers were referred because of suspicion of a cardiac anomaly during an obstetric scan. The mean gestational age at diagnosis was 26 weeks. Termination of pregnancy occurred in 98 cases. There were 92 deaths in the continuing pregnancies and a survival rate of 60%. The detection rate of CHD prenatally continues to increase as obstetric screening for cardiac malformations becomes more widespread. Diagnostic categories continue to be skewed toward more complex forms of malformation, although comparisons with previous studies show some trends. In particular, there are proportionately fewer pregnancies with extracardiac malformations. In addition, the outcome in continuing pregnancies is substantially improved from previous reports.

Abnormalities, Multiple↗
PubMedDate not supplied

The normal pattern of pulmonary venous flow on pulsed Doppler examination of the human fetus.

The pattern of pulmonary venous flow was studied in 52 normal fetuses between 16 weeks gestation and term. A characteristic flow profile was defined. This was similar to that described in the child and adult and different from the pattern of flow in the systemic veins described in the fetus. The velocity of flow increased with gestation and was not influenced by heart rate. The velocity-time integral showed that systolic flow was 2.0 +/- 0.3 times the flow in diastole. Pulsed Doppler echocardiography demonstrates a distinctive pattern of pulmonary venous blood flow that reflects left atrial hemodynamics.

Adult↗
PubMedDate not supplied

Isomerism of the atrial appendages in the fetus.

Thirty hearts from fetuses with visceral heterotaxy were examined to determine the range of cardiac malformations. By examining the morphology of the atrial appendages, 20 hearts were identified as having left isomerism (67%) and 10 hearts right isomerism (33%). Fifteen of the hearts with left isomerism had biventricular atrioventricular connections and five had univentricular atrioventricular connections. All 10 hearts with right isomerism had biventricular atrioventricular connections. Flow to the pulmonary arteries was obstructed or occluded in 6 hearts with left isomerism (30%) and 7 hearts with right isomerism (70%). Obstruction to aortic flow was present in 4 hearts with left isomerism (20%). Anomalies of the systemic and pulmonary veins were common in both groups. The suprarenal portion of the inferior caval vein was interrupted in 11 hearts with left isomerism (55%) and 1 heart with right isomerism (10%). Atrioventricular septal defect was present in 13 hearts with left isomerism (65%) and 9 hearts with right isomerism (90%). The arrangement of the liver or stomach in each group was not consistent, nor was the status of the spleen. The constellations of cardiac malformations in both groups corresponded to those known in postnatal life and similar guidelines for their identification were applicable.

Aorta, Thoracic↗
PubMedDate not supplied

Fetal diagnosis of fatal congenital heart disease.

The identification of the structure of the fetal heart became possible in the early 1980s as the resolution of ultrasound equipment improved. At that time, use of fetal echocardiography was confined to mothers whose fetuses were at increased risk of developing congenital heart disease, although only 10% of congenital heart disease occurs in this group. In 1985 a French group suggested that obstetricians involved in routine scanning be taught a simplified form of heart scanning, which made it possible to screen the general pregnant population for major anomalies. This form of heart scanning involved the examination of one section of the heart, the four-chamber view, and this approach greatly increased the potential impact of fetal echocardiography. As a result of the success of this program in both the United Kingdom and France, a continually increasing proportion of major cardiac defects are detected prenatally. There is almost no form of structural heart disease seen in a four-chamber projection during a routine scan that will not result in the eventual death of the child or young adult. Surgery may delay or defer this event, depending on the anatomic anomaly, but in general the outlook for affected children and their chance of reaching healthy adult life is poor. Most parents who learn this before 20 weeks of pregnancy will elect to interrupt the pregnancy. As a result a decline in the number of postnatal cases of some defects, such as the hypoplastic left-heart syndrome, can be documented in postnatal life.

Abortion, Eugenic↗