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Biomedical subjects

L D Allan

Publications and source records attributed to L D Allan.

At least 37 records · Page 2Linked to original sources
PubMed1997

Comparison of three-dimensional echocardiographic assessment of volume, mass, and function in children with functionally single left ventricles with two-dimensional echocardiography and magnetic resonance imaging.

Diminished systolic function or inappropriate hypertrophy are considered risk factors for outcome following the Fontan procedure. These parameters are difficult to assess in univentricular hearts that do not conform to the uniform shapes prescribed by conventional 2-dimensional imaging volume algorithms. Three-dimensional echocardiography requires no geometric assumptions and has been validated in both normal and distorted left ventricles. To assess the feasibility and accuracy of this technique in patients with univentricular hearts, we compared 2- and 3-dimensional echocardiographic estimates of ventricular volume, ejection fraction, and mass in patients with functionally single left ventricles with results obtained by magnetic resonance imaging (MRI). Twelve patients with functionally single left ventricles (6 months to 22 years) underwent examination by all 3 modalities. Correlation and agreement with MRI were calculated for volumes, ejection fraction, and mass. Three-dimensional echocardiographic comparison with MRI yielded a bias of 3.4 +/- 5.5 ml and 14.2 +/- 8.3 ml for systolic and diastolic volumes, respectively. Agreement analysis for mass showed a bias of 5.8 +/- 8.4 grams. Two-dimensional echocardiography showed less agreement for both volumes and mass (bias of -2.9 +/- 8.1, 2.9 +/- 10.4 ml and -8.3 +/- 12.0 g for volume and mass, respectively, p >0.05). Ejection fraction by 3-dimensional echocardiography showed significantly closer agreement with MRI (bias of 4.4 +/- 5.3%) than 2-dimensional echocardiography (bias of 8.5 +/- 10.3%, p = 0.04). Thus, 3-dimensional echocardiography provides estimates of ventricular volumes, ejection fraction, and mass that are comparable to MRI in this select group of patients with single ventricles of left ventricular morphology.

Adolescent↗
PubMed1997

Abnormal pulmonary venous return diagnosed prenatally by pulsed Doppler flow imaging.

Pulsed Doppler ultrasound has been used to characterize distinctive pulmonary venous flow patterns in the normal fetus and child. Changes in these characteristic flow patterns have been related to abnormal atrial and ventricular hemodynamics. We report a case of total anomalous pulmonary venous return diagnosed prenatally because of an abnormal pulsed Doppler echocardiographic flow pattern, even though color flow mapping appeared to demonstrate normal pulmonary venous drainage. This case demonstrates the importance of obtaining pulsed Doppler pulmonary venous flow profiles during fetal echocardiography, especially in cases of complex congenital heart disease.

Blood Flow Velocity↗
PubMed1997

Anatomical and echocardiographic correlates of normal cardiac morphology in the late first trimester fetus.

OBJECTIVES: To describe the normal cardiac morphology as seen by transvaginal ultrasound imaging in the first trimester fetus and to compare it with the morphology of the heart as seen by microdissection at the same gestational age. DESIGN: In 53 mothers undergoing early sonography, the fetal heart was examined and the images recorded. The gestational age range was 5-12 weeks of gestation, which represents 21 to 70 days after conception. Images were analysed frame by frame and compared with the anatomy of embryos and fetuses at the same gestational ages. RESULTS: After the 9th week of gestation, four cardiac chambers, the aortic origin, and the pulmonary artery could be identified on cross sectional echocardiography in conjunction with colour flow Doppler. At 9 weeks, the apex pointed anteriorly and the right ventricle and pulmonary artery lay to the right of the midline. By the 11th week of gestation, the apex pointed to the left and the pulmonary artery lay to the left of the midline as in the older fetus. Between 9 and 12 weeks' gestation the aorta was larger than the pulmonary artery. These findings were confirmed in the microdissected hearts. CONCLUSIONS: The current quality of ultrasound images obtained using transvaginal transducers in the first trimester fetus allows the study of fetal cardiac anatomy. Some of the later developmental changes can be demonstrated. As technology improves further the details of earlier cardiac morphogenesis may also become visible.

Dissection↗
PubMed1997

Sonographic detection of parallel great arteries in the fetus.

OBJECTIVE: Of all fetal malformations, those affecting the heart, particularly the great arteries, are most commonly overlooked during obstetric sonography. The appearance of normally related great arteries in the fetus is described. Abnormal parallel great artery orientation was detected on sonography in 24 fetuses over a 3-year period. This abnormality was most commonly due to double outlet right ventricle. CONCLUSION: Examination of the cardiac outflow tracts during obstetric sonography can detect great artery malformations prenatally, allowing optimum perinatal management.

Aorta↗
PubMed1996

Atresia or absence of the left-sided atrioventricular connection in the fetus: echocardiographic diagnosis and outcome.

Our objective was to describe the appearance of atresia of the left-sided atrioventricular valve on the four-chamber view of the fetal heart. Twenty-four cases of atresia of the left-sided atrioventricular connection were detected over a 2-year period. Cases were analyzed according to the appearance of the four-chamber view and the connections of the great arteries. All cases were referred because the left-sided ventricle was smaller than the right. There were five different groups of cardiac anomaly detected. Associated findings varied according to the diagnostic group. It was concluded that it is possible to identify atresia of the left-sided atrioventricular connection accurately during obstetric ultrasound examination by evaluation of the four-chamber view. However, the appearance of this view varies with the diagnosis. Each diagnostic group has different implications in terms of associated extracardiac malformations and postnatal management.

Diagnosis, Differential↗
PubMed1996

Outcome of isolated congenital complete heart block diagnosed in utero.

OBJECTIVE: To establish identifiable prenatal factors in fetal heart block which might predict death in utero, the need for intervention, or the probability of pacemaker requirement. SETTING: Tertiary referral unit for fetal echocardiography. SUBJECTS: 36 fetuses with congenital complete heart block and structurally normal hearts identified between 1980 and 1993. METHODS: Maternal anti-Ro antibody status was documented. Prenatal variables examined included absolute heart (ventricular) rate, change in rate, and development of hydrops fetalis. Postnatally, heart rate, need for pacing, and the indications for pacing were detailed. RESULTS: Of the total of 36 patients, there are 24 survivors; 11 are paced. Of those fetuses which died, two were electively aborted for severe hydrops, seven died in utero, two were immediate postnatal deaths, and one was an unrelated infant death. The trend was for the heart rate to decrease during fetal life and postnatally. Fetuses with deteriorating cardiac function did not always show the lowest heart rates. Bradycardia of less than 55 beats/min in early pregnancy or rapid decrease in heart rate prenatally were poor prognostic signs. Hydrops was also associated with bad outcome, 10 out of the 12 hydropic fetuses dying (83%). Of 10 fetuses presenting with a heart rate above 60/min, nine survived of whom three required pacing. Of seven presenting with heart rates of 50/min or less, only three survived and two of these required pacing. Of the two fetuses with negative maternal anti-Ro antibody status one died in utero and one required heart transplantation after pacemaker insertion. CONCLUSIONS: Isolated complete heart block identified in fetal life does not always have a good prognosis. An individual heart rate does not accurately predict the outcome in utero or the need for postnatal pacing. Regular, careful monitoring during pregnancy is required in order to optimise care and timing of any interventions.

Cardiac Pacing, Artificial↗
PubMed1996

Quantitative three dimensional echocardiography in patients with pulmonary hypertension and compressed left ventricles: comparison with cross sectional echocardiography and magnetic resonance imaging.

OBJECTIVE: To evaluate the accuracy of quantitative three dimensional echocardiography in patients with deformed left ventricles. DESIGN: Three dimensional and cross sectional echocardiographic estimates of left ventricular volume and ejection fraction were prospectively compared to those obtained from magnetic resonance imaging. SETTING: Echocardiography laboratory of a university hospital. PATIENTS: 26 patients (9 months to 42 years, median age 11 years) with pulmonary hypertension and fixed reversal of normal interventricular septal curvature. MAIN OUTCOME MEASURES: Left ventricular end diastolic and end systolic volumes and ejection fraction. RESULTS: Three dimensional echocardiographic comparison to magnetic resonance imaging (MRI) yielded r values of 0.94 and 0.87 with a bias of -6.9 (SD 6.9) ml and -16 (11.2) ml for systolic and diastolic volumes respectively. Inter-observer variability was minimal (8.3% and 7.6% respectively). Cross sectional echocardiography gave correlation coefficients of 0.62 and 0.80 and bias of 3.1 (14.1) ml and 16.3 (18.3) ml for systolic and diastolic volumes respectively. Ejection fraction by three dimensional echocardiography also had closer agreement with MRI (bias = 1.1 (7.7)%) than cross sectional echocardiography (bias = 4.4 (13.9)%). CONCLUSIONS: Three dimensional echocardiography provides reliable estimates of left ventricular volumes and ejection fraction, comparable to magnetic resonance imaging in pulmonary hypertension patients with compressed ventricular geometry. Because it eliminates the need for geometric assumptions it shows closer agreement with magnetic resonance imaging in that setting than cross sectional echocardiography.

Adolescent↗
PubMed1996

Fetal cardiology.

Several publications continue to address the topic of screening for fetal congenital heart disease with widely differing results. The ideal timing and method of fetal heart scanning is still under debate. An abnormal fetal heart position may indicate abnormality, particularly of the great arteries. The management of several problems that present to the fetal cardiologist are detailed in recent publications.

Fetal Heart↗
PubMed1996

The fetal heart in diaphragmatic hernia.

Cardiac evaluation is an important part of the investigation of a fetus with a diaphragmatic hernia. The heart is displaced by the physical presence of the abdominal contents in the chest, and the flow dynamics within the heart are altered. This can produce secondary diminution of chamber growth, particularly of the left heart. Structural heart malformation is also a frequently associated finding. Evaluation of cardiovascular flow profiles may give us further understanding of the pathophysiology of this lesion and may help to predict those fetuses that might benefit from intrauterine therapy.

Fetal Heart↗
PubMed1995

Therapeutic trial of sympathomimetics in three cases of complete heart block in the fetus.

BACKGROUND: A total of 36 fetuses with isolated congenital complete heart block and structurally normal hearts have been seen in the department of fetal echocardiography since 1980. Although the prognosis is good in the majority of cases, those who develop intrauterine cardiac failure have a high mortality. The aim of this study was to investigate the contribution to management of sympathomimetic therapy by comparing two possible agents administered to the mothers. METHODS AND RESULTS: The effect of two sympathomimetic agents, isoprenaline and salbutamol, was compared in three patients with isolated complete heart block. Fetal heart rate and indexes of cardiac function were monitored during therapy. Maternal cardiovascular status was also regularly assessed. Dosage of isoprenaline increased from 1 to 12 micrograms/min, and salbutamol increased from 4 to 64 micrograms/min during the trial. No significant change was detected with isoprenaline therapy, but all fetuses showed an increase in heart rate and improvement in ventricular function with salbutamol. Salbutamol was maintained until delivery in one case with evidence of cardiac failure, with resolution of fetal hydrops. All three delivered in good condition close to term. Two of three required pacing in the neonatal period. CONCLUSIONS: We conclude that salbutamol can be effective in the treatment of fetal complete heart block and should be considered in patients with this condition where there is evidence of deteriorating cardiac function.

Albuterol↗
PubMed1995

Survival after fetal aortic balloon valvoplasty.

The pre- and postnatal course of a child surviving after successful intrauterine balloon aortic valvoplasty for critical aortic stenosis is described. She is now well at 4 years of age. A clearer understanding of the hemodynamics in such cases and improved catheter technology are necessary before this is advocated as a generally applicable technique. However, the outcome in this case is promising for the future of fetal interventional procedures.

Aortic Valve Stenosis↗
PubMed1995

Echocardiographic-anatomical correlations in aorto-left ventricular tunnel.

OBJECTIVE: To investigate the echocardiographic, morphological, and histological appearances of aorto-left ventricular tunnel observed in four fetal hearts and compare the findings with those reported in older patients with the malformation. BACKGROUND: Previous studies have concentrated on clinical features of the malformation from birth to adult life and have speculated on either its embryological formation or its acquisition during late intrauterine life. The presentation of a large series of cases in fetal life is a unique opportunity to study the malformation at an early stage in its natural course. METHODS: A retrospective study was performed of four cases of aorto-left ventricular tunnel discovered among 872 cases of congenital abnormalities diagnosed at a tertiary centre for fetal echocardiography. Detailed echocardiographic and anatomical observations were made of the malformation as identified during fetal life. The precise anatomical arrangement was determined and compared with previous descriptions found in journals published in English. RESULTS: In fetal life, as after birth, the malformation is characterised by enlargement and hypertrophy of the left ventricle, enlargement of the aortic root, and free regurgitation at the level of the aortic valve. Anatomical abnormalities are found at the aortic ventriculoarterial and sinutubular junctions as well as in the intervening aortic wall. These are unrelated to necrosis, ischaemia, or the presence of mucopolysaccharides. CONCLUSIONS: The lesion is a developmental abnormality that should be reliably diagnosed by fetal echocardiography combined with colour flow Doppler echocardiography during the mid-trimester. The exact anatomical relations clarified by this study are pertinent to diagnosis and subsequent surgical correction.

Aorta↗
PubMed1994

Prospective diagnosis of 1,006 consecutive cases of congenital heart disease in the fetus.

OBJECTIVE: This report describes our experience with fetal congenital heart disease since 1980. BACKGROUND: Knowledge and expertise in the diagnosis, management and natural history of fetal congenital heart disease is increasingly demanded by both obstetricians and parents. The analysis of a large series should help the pediatric cardiologist to provide this service. METHODS: The notes of 1,006 patients, where a prospective diagnosis of fetal congenital heart disease was made, were reviewed. The reason for referral, the diagnosis made, the accuracy of diagnosis, the fetal karyotype and the outcome of the pregnancy were noted. The cases were grouped into malformation categories, and the spectrum of disease seen was compared with that found in infants. RESULTS: Most fetal cardiac anomalies are now suspected by the ultrasonographer during obstetric scanning. A different incidence of abnormalities is seen compared with that expected in infants. Chromosomal anomalies were more frequent in the fetus than in live births. The accuracy of diagnosis was good. The survival rate after diagnosis was poor because of frequent parental choice to interrupt pregnancy and the complexity of disease. CONCLUSIONS: A large experience with fetal congenital heart disease allows the spectrum of disease to be described with accuracy and compared with that in infancy. Knowledge of the natural history of heart malformations when they present in the fetus allows accurate counseling to be offered to the parents. If the trend in parental decisions found in this series continues, a smaller number of infants and children with complex cardiac lesions will present in postnatal life.

Female↗
PubMed1994

Coarctation of the aorta: difficulties in prenatal diagnosis.

OBJECTIVE: To formulate echocardiographic criteria for the prenatal diagnosis of coarctation of the aorta. DESIGN: A retrospective study examining the echocardiograms of fetuses with a verified aortic arch abnormality and those in whom the diagnosis was suspected prenatally but was not subsequently confirmed. SETTING: Tertiary referral centre for fetal echocardiography. PATIENTS: 87 fetuses in whom the diagnosis of coarctation was correctly made in 54, suspected but unproved in 24, and overlooked prenatally in nine. MAIN OUTCOME MEASURES: Measurements of left and right ventricular size, the diameters of the great arteries, the diameters of the left and right atrioventricular valvar orifices, the appearance of the aortic arch, and the direction of the flow of blood across the foramen ovale. RESULTS: Measurements of the ventricular widths, diameters of the great arteries, or the diameters of the atrioventricular valvar orifices, did not allow clear distinction between cases that definitely had a coarctation and those in whom the diagnosis was unproved. The appearance of the aortic arch, particularly in the horizontal projection, was more helpful in distinguishing cases of coarctation, although this also was not always diagnostic. A predominantly left to right shunt across the foramen ovale was detected more often in cases with a substantiated coarctation (58%) than in those with an unproved diagnosis (12%). CONCLUSIONS: The most severe forms of coarctation are associated with relative hypoplasia of the left heart structures compared with the right and a correct diagnosis can be made in early pregnancy. The milder forms of coarctation, however, are consistent with a normal early fetal echocardiogram. In late pregnancy it may be impossible to exclude coarctation categorically as the right heart structures may appear larger than the left in the normal fetus. Thus although a combination of echocardiographic features can correctly identify aortic arch anomalies in the fetus, none either alone or in combination, could clearly distinguish between real and false positive cases, particularly in late gestation.

Aorta, Thoracic↗
PubMed1994

Fetal congenital heart disease: diagnosis and management.

The most important papers address controversial aspects of fetal cardiology, for example, screening for congenital heart disease (CHD), the diagnosis and the accuracy of diagnosis, and the management of fetal tachycardias. There are some interesting additions to the literature although some conclusions require further evaluation.

Female↗
PubMed1993

Intrathoracic cardiac position in the fetus.

In a 4-year period, 83 fetuses have been noted to have an abnormal fetal heart position within the thorax on fetal echocardiography. In 55 cases where the heart lay in the right chest, this was due to the presence of a left-sided diaphragmatic hernia; in one case, the heart was abnormally far into the left chest because of a left-sided diaphragmatic hernia. Of the remaining 27 cases, the heart lay in the right chest in 16 cases. In seven of those 16, there was a congenital heart malformation; in six, there were lung anomalies; a hiatus hernia was present in one; both congenital heart disease and lung abnormality were present in one and one fetus had isolated dextrocardia. In nine cases, the heart lay in the center of the chest and in three, the heart lay further to the left than normal. Congenital heart disease was found in nine of these 12. Chromosomal anomalies were found in four of the 27 cases with an abnormal heart position but an intact diaphragm. In summary, it is important to be familiar with the normal cardiac orientation within the thorax and to investigate abnormalities of position. A diaphragmatic hernia will be the most common underlying cause but, where the diaphragm is intact, other explanations must be sought in order to counsel correctly or plan appropriate perinatal management. Lung disorders, congenital heart disease and chromosomal anomalies will be the principal differential diagnoses.

Journal Article↗