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PubMed2003

Closure of muscular ventricular septal defects guided by en face reconstruction and pictorial representation.

BACKGROUND: A surface reconstruction of the location and dimensions of muscular ventricular septal defects (VSDs) on right ventricular (RV) septal surface could serve as a better guide to surgical closure amid different classifications and confusing terminologies. METHODS: We reconstructed muscular VSD requiring surgery on an en-face view of the RV septal surface from echocardiographic orthogonal views in 34 consecutive patients. The location, dimensions of the defects, and relation to various RV septal landmarks are illustrated as a diagram. Recommendations are presented regarding surgical approach to the defects, along with predictions on the possibility of residual defects and heart block. RESULTS: Surgical findings were as predicted by the diagram in the 27 patients who underwent VSD closure. Seven infants (2.5 to 4.9 kg) underwent pulmonary artery (PA) banding based on predictions of heart block or major residual defects. Two patients with predicted risk of heart block underwent VSD closure with heart block ensuing in one of them. Based on the diagram limited ventriculotomy (n = 2) or detachment of tricuspid leaflets (n = 6) aided access to the VSD. Among patients undergoing VSD closure only 1 patient had a major residual defect that required PA banding. There were clinically insignificant residual defects in 8 patients. Four patients (12%) were anticipated preoperatively because of surgical inaccessibility and intentionally left alone. CONCLUSIONS: En-face reconstruction of single or multiple muscular VSDs is feasible from orthogonal echocardiographic views. It helps plan the surgical approach and predict the likelihood of heart block and residual defects after surgery.

Cardiac Surgical Procedures↗
PubMed1992

Incidence and natural course of trabecular ventricular septal defect: two-dimensional echocardiography and color Doppler flow imaging study.

This study was designed to determine the prevalence of trabecular ventricular septal defect (t-VSD) in neonates and to evaluate the effects of its location, morphologic features, and size on its natural course during infancy. One thousand twenty-eight term newborn infants were examined by color Doppler flow imaging with orthogonal ultrasonographic views. Ten girls and 11 boys (2.0%) were found to have t-VSD. The natural course of the defect was examined in 42 consecutive cases, consisting of this group of 21 neonates and another group of 21 neonates with t-VSD. The morphologic features of the defect within the trabecular septum were classified as one or two defects (36 cases) and as a mesh-like defect (six cases). Reduction in size began from the right ventricular side or from within the trabecular septum. Spontaneous closure occurred most commonly during the first 6 months of life and was observed in 32 cases (76%) by 12 months of age: the frequency of closure was not related to the morphologic features and the initial size of the defect, but apical defects tended to have higher persistent patency than did defects in other locations (p less than 0.05). We conclude that the frequency of t-VSD in neonates and the frequency of spontaneous closure during early infancy are higher than previously believed. This information is important for predicting the natural course of t-VSD and deciding on its proper management.

Blood Flow Velocity↗
PubMed1996

Decision making for the surgical management of aortic coarctation associated with ventricular septal defect.

Coarctation of the aorta and associated ventricular septal defect may be repaired simultaneously or by initial coarctation repair with or without banding of the pulmonary artery. The question is whether specific preoperative criteria can enable the surgeon to choose the optimal surgical management. Between 1980 and 1993, 80 infants younger than 3 months with coarctation and ventricular septal defect were treated surgically. In 64 infants (multistage group), simple coarctation repair was performed through a posterolateral approach, with concomitant banding of the pulmonary artery in 10 infants. Twenty ventricular septal defects were closed as a secondary procedure and four were closed as a tertiary procedure. Sixteen infants (single-stage group) underwent one-stage repair through an anterior midline approach. The total in-hospital mortality rate was 7.5%. Freedom from recoarctation after 5 years was 91.3% in the multistage group versus 60.0% in the single-stage group (p = 0.018). Freedom from secondary ventricular septal defect treatment in the multistage group after 5 years was 40.7%, versus 100% in the single-stage group (p = 0.016). Thirty-seven ventricular septal defects (47.8%) closed spontaneously. In particular, the preoperative left-to-right shunt and extension of the perimembranous VSD into the inlet or outlet were risk factors for the need for eventual surgical ventricular septal defect closure after initial coarctation repair. On the basis of these two risk factors, the probability of the need for eventual surgical treatment of ventricular septal defect after initial coarctation repair can be calculated. This policy offers a well-considered choice between single-stage and multistage repair, weighing the risk of secondary ventricular septal defect treatment versus the risk of recoarctation. Finally, the number of surgical procedures per infant will be as low as possible.

Aortic Coarctation↗
PubMed1997

Extending the concept of the autograft for complete repair of transposition of the great arteries with ventricular septal defect and left ventricular outflow tract obstruction: a report of ten cases of a modified procedure.

BACKGROUND: In most cases of transposition of the great arteries with ventricular septal defect and left ventricular outflow tract obstruction, a Lecompte procedure (réparation à l'étage ventriculaire) is possible without interposition of a conduit between the right ventricle and pulmonary artery. However, the anterior location of the pulmonary arteries after the Lecompte maneuver may be a potential cause for right ventricular outflow obstruction, which continues to be reported in 5% to 25% of cases. We have used a tubular segment of aortic autograft to connect the pulmonary artery, left in the orthotopic posterior position (without the Lecompte maneuver), to the right ventricle in 10 consecutive patients with transposition, ventricular septal defect, and left ventricular outflow tract obstruction. METHODS: Ten consecutive patients aged 2 months to 11 years (mean 32 months) have undergone a modified Lecompte operation. Eight had severe pulmonary stenosis, two had pulmonary atresia, and four had a restrictive ventricular septal defect at the time of the operation. Two had multiple ventricular septal defects. Seven had undergone one (n = 5) or two (n = 2) previous modified Blalock-Taussig shunts. All patients underwent a total correction with left ventricular-aortic intraventricular connection (four needed a ventricular septal defect enlargement), connection between the right ventricle and pulmonary arteries with a tubular segment of autograft aorta, without the Lecompte maneuver (anterior location of the bifurcation of the pulmonary arteries) on the right (n = 6) or the left (n = 4) of the aorta. No valvular device was used for the right ventricular outflow repair. RESULTS: No early or late deaths occurred. One patient with multiple ventricular septal defects needed an early (2 weeks) reoperation for a residual muscular ventricular septal defect. All patients are currently in New York Heart. Association class I, without medications, in sinus rhythm, at a mean follow-up of 30 months. Late results up to 3.6 years show no calcification on the chest roentgenogram, and at the most recent echocardiogram, right ventricular pressures were low (25 to 40 mm Hg, mean 33 mm Hg) and no significant gradient (over 10 mm Hg) was found between the right ventricle and pulmonary arteries. Left and right ventricular function was satisfactory. CONCLUSION: This modification of the Lecompte operation using a segment of autograft allows an excellent early and late result, with no danger of compression of anteriorly placed pulmonary arteries, no significant right ventricular outflow obstruction, and normal appearance of the tubular autograft. In view of laboratory and clinical evidence, normal growth of the autograft can be anticipated. It allows an elective correction of transposition, ventricular septal defect, and left ventricular outflow tract obstruction without a previous Blalock-Taussig shunt (three patients) and correction at a young age (three patients younger than 1 year).

Aorta↗
PubMed1997

One-stage complete unifocalization in infants: when should the ventricular septal defect be closed?

BACKGROUND: The decision whether to close the ventricular septal defect at the time of unifocalization in patients with pulmonary atresia, ventricular septal defect, and major aortopulmonary collaterals may be difficult. The purpose of this study was to develop morphologic and physiologic methods to aid in deciding whether to close the ventricular septal defect in patients undergoing one-stage unifocalization. METHODS: Between July 1992 and April 1996, 27 infants with pulmonary atresia, ventricular septal defect, and aortopulmonary collaterals were treated at our institution. Midline complete unifocalization was performed in 25 patients-the ventricular septal defect was closed in 17 and left open in eight. Two patients with severe distal collateral stenoses underwent staged unifocalization. Pulmonary artery and collateral sizes were measured from preoperative angiograms and used to calculate the indexed cross-sectional area of the total neopulmonary artery bed. An intraoperative pulmonary flow study previously validated with experiments in neonatal lambs was performed in six patients: the unifocalized neopulmonary arteries were perfused with a known flow and pulmonary artery pressures were recorded. RESULTS: The neopulmonary artery index was greater in patients who underwent ventricular septal defect closure than in those who did not (p = 0.001), although the values did overlap. This index correlated with the postoperative right ventricular/left ventricular pressure ratio (p = 0.037). Mean pulmonary artery pressures obtained during the intraoperative flow study and after bypass were comparable. CONCLUSION: The total neopulmonary artery index correlates with postrepair right ventricular/left ventricular pressure ratio and is useful in deciding when to close the ventricular septal defect if it is larger than 200 mm2/m2. The pulmonary flow study is helpful in deciding whether to close the ventricular septal defect in all patients.

Adolescent↗
PubMed2003

Correlation of elevated leptin levels in amniotic fluid and maternal serum in neural tube defects.

OBJECTIVE: To measure maternal serum and amniotic fluid leptin concentrations in pregnant women diagnosed antenatally as having fetuses with a neural tube defect in the second trimester. METHODS: Twenty pregnant women who had fetuses with a neural tube defect detected on ultrasonography (neural tube defect group) in the second trimester and 20 women who had abnormal triple screens indicating an increased risk for Down syndrome but had healthy fetuses (control group) were enrolled in the study. Amniotic fluid was obtained by amniocentesis, and maternal serum samples were taken simultaneously. RESULTS: The mean leptin levels in amniotic fluid (P <.001) and maternal serum (P <.05) of patients who had fetuses with a neural tube defect were found to be significantly higher than control group levels. The mean leptin levels in maternal serum of both groups were also higher than leptin levels in amniotic fluid (P <.05 for the neural tube defect group and P <.001 for the control group). Although there were significant correlations between maternal weight, weight gain, body mass index at the time of amniocentesis, and maternal serum leptin concentrations in both groups, a significant correlation between leptin concentrations in maternal serum and amniotic fluid was found only in the neural tube defect group (P <.05). CONCLUSIONS: We found significantly higher leptin levels in both amniotic fluid and maternal serum of patients who had fetuses with a neural tube defect. We suggest that the main source of leptin in amniotic fluid of pregnant women who had fetuses with a neural tube defect is the leakage into amniotic fluid from cerebrospinal fluid. The increase of maternal serum leptin concentrations has been attributed to the transportation of amniotic fluid leptin to the maternal circulation.

Adult↗
PubMed1995

Homocysteine metabolism in pregnancies complicated by neural-tube defects.

Folic acid taken around the time of conception can prevent many neural-tube defects. Women with low-normal vitamin B12 values may also be at increased risk. We considered whether homocysteine metabolism via the enzyme methionine synthase, which requires both folate and B12, could be the critical defect in folate-related neural tube defects. Blood was obtained during pregnancies that produced 81 infants with neural-tube defects and 323 normal children. Samples were assayed for homocysteine, methylmalonic acid, plasma folate, red-cell folate, and B12. Mothers of children with neural-tube defects had significantly higher homocysteine values (8.62 [SD 2.8] mumol/L) than did B12-matched controls (7.96 [2.5] mumol/L, p = 0.03). The difference was significant (p = 0.004) in the lower half of the B12 distribution after adjusting for plasma folate. Our study shows that an abnormality in homocysteine metabolism, apparently related to methionine synthase, is present in many women who give birth to children with neural-tube defects. Overcoming this abnormality is likely to be the mechanism by which folic acid prevents neural-tube defects. These findings suggest that the most effective periconceptional prophylaxis to prevent neural-tube defects may require B12 as well as folic acid.

5-Methyltetrahydrofolate-Homocysteine S-Methyltran↗
PubMed1986

Pulmonary atresia with ventricular septal defect: preoperative and postoperative responses to exercise.

Between April 1982 and June 1984, maximal exercise testing was performed 35 times in 34 consecutive patients with pulmonary atresia and ventricular septal defect (14 studies in patients without repair, 11 studies in patients with partial repair [insertion of a right ventricle to pulmonary artery conduit without ventricular septal defect closure] and 10 studies in patients with complete repair [insertion of a conduit with septal defect closure]). Total work performed, maximal power achieved, exercise time and maximal oxygen uptake were significantly greater in patients after partial or complete repair than in patients without repair. Systemic arterial blood oxygen saturations at rest and during exercise were directly related to the degree of repair. Although heart rate at rest in the three study groups was similar to that in a separate group of normal control subjects, patients in all three study groups had a blunted heart rate response to exercise. The ventilatory equivalent for oxygen was increased both at rest and during exercise for patients without conduit repair and those with a right ventricle to pulmonary artery conduit without ventricular septal defect closure but was similar to that of control subjects in the group with conduit insertion and septal defect closure. This study indicates that patients with pulmonary atresia and ventricular septal defect have decreased exercise tolerance both before and after corrective surgery. Exercise tolerance improves significantly after placement of a conduit from the right ventricle to the pulmonary artery with or without ventricular septal defect closure. Although no further improvement in exercise tolerance occurs with closure of the septal defect, ventilatory function and systemic arterial blood oxygen saturation are improved.

Adolescent↗
PubMed1999

Echocardiographic diagnosis alone for the complete repair of major congenital heart defects.

OBJECTIVES: The study was done to determine the diagnostic accuracy of echocardiography alone in the preoperative diagnosis of children with major congenital heart defects undergoing primary complete repair. BACKGROUND: Although echocardiography is well established as the first-line imaging technique for the diagnosis of all forms of congenital heart disease, most institutions continue to perform cardiac catheterization prior to complete repair of more complex defects. METHODS: To determine the diagnostic accuracy of echocardiography alone and echocardiography plus catheterization, we reviewed the records of 503 children with major congenital heart defects who underwent primary complete repair at our institution between July 1992 and June 1997. We included children with transposition of the great arteries, tetralogy of Fallot, double-chamber right ventricle, interrupted aortic arch, aortic coarctation, atrioventricular septal defect, truncus arteriosus, aortopulmonary septal defect, and totally anomalous pulmonary venous return. We excluded children with less complex defects such as isolated shunt lesions, as well as those with the most complex defects that would require surgical palliation (e.g., functional univentricular heart). We defined major errors as those that increased the surgical risk and minor errors as those that did not. Errors in diagnosis were determined at surgery. RESULTS: Eighty-two percent of children (412 of 503) underwent surgery after preoperative diagnosis by echocardiography alone. There were 9 major (2%) and 10 minor errors in the echocardiography alone group and 7 major and 5 minor errors in the echocardiography plus catheterization group. The most common type of error was misidentification of coronary artery anatomy in patients with transposition of the great arteries. No error in either group resulted in surgical morbidity or mortality. CONCLUSIONS: This study suggests that echocardiography alone is an accurate tool for the preoperative diagnosis of major congenital heart defects in most children undergoing primary complete repair, and may obviate the need for routine diagnostic catheterization.

Adolescent↗
PubMed1998

Epidemiology and diagnosis of ventricular septal defect in Malta.

Malta is a small island with minimal changes in its population, making it an ideal location for epidemiological and historical studies dealing with congenital heart malformations. Ventricular septal defect was studied retrospectively from 1930 to 1994. A sharp and significant decline in age at diagnosis was found, predating echocardiography. All defects are now diagnosed by echocardiography, which has resulted in an increased prevalence of this lesion as seen at birth, particularly of minor defects. The prevalence of ventricular septal defect from 1990 to 1994 was 3.85/1000 live births, with 3.03/1000 not needing surgery and 0.83/1000 requiring operative intervention. Half the defects closed spontaneously. The majority of ventricular septal defects overall, and those spontaneously closing, were muscular defects. The overall prevalence at birth was significantly higher than that reported in recent studies using similar methodologies, implying that the reported rate is more likely to be the true prevalence at birth of clinically detectable defects.

Age Distribution↗
PubMed1999

Transcatheter closure of secundum atrial septal defects with the new self-centering Amplatzer Septal Occluder.

AIMS: The study was set up to find out whether a new self-centering prosthesis for transcatheter closure of secundum atrial septal defects could overcome the disadvantages of previously described devices. METHODS AND RESULTS: Fifty-two consecutive patients with a significant atrial septal defect were considered for transcatheter closure with the Amplatzer Septal Occluder. The device, made of a Nitinol and polyester fabric mesh, provides a different approach to defect occlusion by stenting the atrial septal defect up to a stretched diameter of 26 mm. Three infants whose large defects were demonstrated on a transthoracic echocardiogram were excluded from transcatheter treatment. On transoesophageal echocardiography, 49 defects ranged from 6-26 mm, in one adult the defect measured 28 mm and this patient was excluded from attempted transcatheter closure. At cardiac catheterization in five further patients, devices were not implanted, in two because the stretched diameter exceeded 26 mm and in three the device was withdrawn because it was unstable or compromised the mitral valve. Thus, device closure was performed in 43 patients. At follow-up after 3 months the complete closure rate was 97%. CONCLUSION: The self-centering Amplatzer Septal Occluder is very efficient and user-friendly and offers interventional closure in 83% of an unselected group of patients presented with an atrial septal defect.

Adolescent↗
PubMed2000

The correction of congenital heart defects with less invasive approaches.

BACKGROUND: The minimally and less invasive approaches for the surgical treatment of different heart diseases are rapidly increasing because of their cosmetic and recovery-related advantages. Presented here are the results of less invasive surgery in 51 patients with congenital heart defects. METHODS: From June 1996 to January 1999, we used less invasive techniques for the correction of congenital heart defects in 51 patients. In 32 patients, we performed right anterolateral thoracotomy (6-13 cm), and on the other 19 patients, we used the partial inferior sternotomy (4-7 cm). The ascending aorta and the caval veins were cannulated in all patients. RESULTS: The following congenital heart defects were corrected: ostium secundum atrial septal defect (n = 35), sinus venosus atrial septal defect with partial anomalous pulmonary venous connection (n = 7), ventricular septal defect (n = 7), tetralogy of Fallot (n = 1), and cor triatriatum sinistrum (n = 1). The average age of the patients was 15 years old ranging from 2 months to 48 years and the average weight 39.6 kg (range 3.8-86 kg). The patients were removed from artificial respiratory support on average 8 hours (range 1-48 hours) after surgery and left the hospital after 7 days (range 2-10 days). In 16 patients, blood transfusions were required, an average 5.7 ml/kg BW (range 1.45-19.75 ml/kg BW). The postoperative course was uneventful in all patients. Follow-up (range 3-33 months, mean 17.5 months) was complete with no late deaths or residual defects. CONCLUSION: The right anterolateral thoracotomy and the partial inferior sternotomy provide a safe approach for the correction of certain congenital heart defects. These techniques enable operative correction without any additional risks being incurred and can be performed with standard instruments and cannulation. Additional approaches for extracorporeal circulation are unnecessary.

Adolescent↗
PubMed2002

Surgical substrates of postoperative junctional ectopic tachycardia in congenital heart defects.

BACKGROUND: Junctional ectopic tachycardia is a major cause of postoperative morbidity after surgery for congenital cardiac disease. To elucidate the mechanism of junctional ectopic tachycardia, surgical correlations were studied in four types of congenital heart defects involving closure of a ventricular septal defect, relief of right ventricular outflow tract obstruction, or both. METHODS: Between 1997 and 1999, a total of 343 consecutive patients underwent repair of tetralogy of Fallot (n = 114), common truncus arteriosus (n = 10), ventricular septal defect (n = 161), and atrioventricular septal defect (n = 58). Variables studied included demographic and bypass data, surgical approaches toward ventricular septal defect closure and relief of right ventricular outflow tract obstruction, and resection as opposed to division of muscle bundles. RESULTS: Junctional ectopic tachycardia occurred most frequently after repair of tetralogy of Fallot (n = 25; 21.9%), with no cases occurring after repair of common trunk, 6 occurring after repair of ventricular septal defect (3.7%), and 6 occurring after repair of atrioventricular septal defect (10.3%). Stepwise logistic regression revealed that resection of muscle bundles (P <.0001), higher bypass temperatures (P <.03), and relief of right ventricular outflow tract obstruction through the right atrium (P <.05) significantly and independently predicted postoperative junctional ectopic tachycardia. CONCLUSIONS: Relief of right ventricular outflow tract obstruction appears to be more important in the causation of junctional ectopic tachycardia than does ventricular septal defect closure, which may explain the higher incidence of this complication after tetralogy of Fallot repair. Muscular resection seems to be more arrhythmogenic than is simple division. Increased traction through the right atrium for relief of right ventricular outflow tract obstruction would fit the hypothesis that enhanced automaticity of the His bundle, the morphologic substrate for junctional ectopic tachycardia, may result from direct trauma or infiltrative hemorrhage of the conduction system. When feasible, techniques avoiding both extensive muscle resection and excessive traction should be applied during resection of right ventricular outflow tract obstruction.

Adolescent↗
PubMed2005

Congenital heart defects and abnormal maternal biomarkers of methionine and homocysteine metabolism.

BACKGROUND: It is well established that folic acid prevents neural tube defects. Although the mechanisms remain unclear, multivitamins containing folic acid may also protect against other birth defects, including congenital heart defects. OBJECTIVE: Our goal was to establish a maternal metabolic risk profile for nonsyndromic congenital heart defects that would enhance current preventive strategies. DESIGN: Using a case-control design, we measured biomarkers of the folate-dependent methionine and homocysteine pathway among a population-based sample of women whose pregnancies were affected by congenital heart defects (224 case subjects) or unaffected by any birth defect (90 control subjects). Plasma concentrations of folic acid, homocysteine, methionine, S-adenosylmethionine (SAM), S-adenosylhomocysteine (SAH), vitamin B-12, and adenosine were compared, with control for lifestyle and sociodemographic variables. RESULTS: After covariate adjustment, case subjects had higher mean concentrations of homocysteine (P < 0.001) and SAH (P < 0.001) and lower mean concentrations of methionine (P = 0.019) and SAM (P = 0.014) than did control subjects. Vitamin B-12, folic acid, and adenosine concentrations did not differ significantly between case and control subjects. Homocysteine, SAH, and methionine were identified as the most important biomarkers predictive of case or control status. CONCLUSIONS: The basis for the observed abnormal metabolic profile among women whose pregnancies were affected by congenital heart defects cannot be defined without further analysis of relevant genetic and environmental factors. Nevertheless, a metabolic profile that is predictive of congenital heart defect risk would help to refine current nutritional intervention strategies to reduce risk and may provide mechanistic clues for further experimental studies.

Adult↗
PubMed2000

Occurrence of congenital heart defects in relation to maternal mulitivitamin use.

The purpose of this study was to assess the relation between maternal multivitamin use and risk for cardiac defects in the offspring, using a population-based approach. The Atlanta Birth Defects Case-Control study is a population-based case-control study of infants born between 1968 and 1980 to mothers residing in metropolitan Atlanta, Georgia. The 958 case infants with nonsyndromic cardiac defects were actively ascertained from multiple sources. The 3,029 infants without birth defects (control infants) were selected from birth certificates by stratified random sampling. Periconceptional multivitamin use, defined as reported regular use of multivitamins from 3 months before pregnancy through the first 3 months of pregnancy, was contrasted with no use during the same time period. Periconceptional multivitamin use was associated with a reduced risk for nonsyndromic cardiac defects in the offspring (odds ratio (OR) = 0.76; 95% confidence interval (Cl): 0.60, 0.97). The risk reduction was strongest for outflow tract defects (OR = 0.46; 95% Cl 0.24, 0.86) and ventricular septal defects (OR = 0.61; 95% Cl: 0.38, 0.99). No risk reduction was evident when multivitamin use was begun after the first month of pregnancy. If these associations are causal, the results suggest that approximately one in four major cardiac defects could be prevented by periconceptional multivitamin use.

Adolescent↗
PubMed1997

Cardiopulmonary physiology after surgical closure of asymptomatic secundum atrial septal defects in childhood. Exercise performance is unaffected by age at repair.

AIMS: Most secundum atrial septal defects, once diagnosed, are corrected at a young age. The evidence to justify early vs delayed or even non-closure is equivocal and little is known regarding long-term effects of later closure. This is particularly pertinent to those patients awaiting transcatheter closure of their defect for whom a device is only just becoming available. We examined the exercise cardiorespiratory physiology of children surgically treated for an isolated secundum defect. METHODS AND RESULTS: One hundred and six healthy control children and 22 children more than 6 months after surgical repair for an isolated secundum atrial septal defect were studied. All were asymptomatic. Measurements of effective pulmonary blood flow, stroke volume, arteriovenous oxygen difference, minute ventilation, heart rate, oxygen consumption and carbon dioxide production were made using a quadrupole mass spectrometer during rest and graded exercise. Data from the normal children allowed calculation of z scores for the atrial septal defect group matched for age, sex, pubertal stage and surface area. Maximal exercise performance was equal between control and atrial septal defect groups, however, the atrial septal defect group had a significantly greater effective pulmonary blood flow and stroke volume but a lower heart rate than controls at a given exercise stage. Stroke volume abnormalities were most closely related to duration of follow-up (29% of the variance explained, P < 0.01) rather than age at surgery. CONCLUSIONS: We were unable to show a medium term benefit from early surgery for an asymptomatic secundum atrial septal defect during exercise. The clinical relevance of the haemodynamic differences that do exist remains unclear.

Adolescent↗
PubMed1978

Defective herpes simplex virus DNA: circular and circular-linear molecules resembling rolling circles.

The formation of defective herpes simplex virus (HSV) in BSC-1 cells and the synthesis of defective virus DNA was studied. The fourth consecutive passage of undiluted virus yielded defective DNA that was 0.008 g/ml more dense than wild type (w.t.) virus DNA. The amount of defective DNA increased at passage 6 concomitantly with the decrease in infectious virus progeny. The synthesis of defective DNA was always accompanied by w.t. virus DNA synthesis. Defective DNA from both infected nuclei and defective virions had a mol. wt. of 100 X 10(6) and was linear as determined by electron microscopy. Electron microscopy of defective virus DNA at passage 6 revealed circular molecules varying in size in addition to linear DNA molecules with the length of intact virion DNA. The circular DNA molecules had contour lengths of 10, 5, 2.5 and less than 2.5 micron. The smallest circular DNA molecules had a contour length of 0.3 micron, possibly one virus gene. In addition, circular-linear DNA molecules were observed in which both the circular and the linear components varied in length. Most of these DNA molecules had circular components of either 2.5 or 5.0 micron, and linear components varying in length from less than 1 to 50 micron. Based on the present study, it is proposed that the S component of w.t. virus DNA is fragmented into small circular molecules that serve as templates for DNA synthesis, possibly by the rolling circle mechanism.

Cell Line↗
PubMed1993

Molecular cloning and characterization of a Sendai virus internal deletion defective RNA.

A small defective Sendai virus RNA was selectively amplified from a virus preparation obtained after serial undiluted passages in embryonated eggs. Preliminary characterization showed that this defective RNA was a true internal deletion defective RNA, containing the 5' and 3' ends of the non-defective viral genomic RNA. Cloning of this RNA after reverse transcription and polymerase chain reaction amplification was performed in such a way that an exact copy of the defective RNA could be obtained by transcription of the plasmid with T7 RNA polymerase. Sequence analysis of the plasmid allowed further characterization of the defective RNA. It was shown potentially to encode a C-terminally truncated nucleocapsid (NP) protein of 162 amino acids. This truncated NP protein was identified in cells naturally infected with the defective virus preparation. Moreover the protein produced was shown to correspond to the protein synthesized in vitro from the T7 polymerase transcript of the cloned defective genome.

Base Sequence↗