Biomedical subjects
Publications and source records attributed to M L Rigby.
Traditionally, neonates with transposition of the great arteries are immediately transferred to a cardiac centre. Travelling to the bedside to perform a balloon atrial septostomy and allowing the child to remain there for a few days before transfer is safe, effective, and a good use of medical resources.
Children with indwelling central venous catheters are at risk of embolisation of catheter fragments. Often their underlying condition means that they are poor candidates for surgical removal. We describe six children who underwent uncomplicated percutaneous transcatheter retrieval (and one who underwent percutaneous line tip repositioning), and suggest that this approach should be the treatment of choice.
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OBJECTIVES: We sought to assess the early and long-term results of subclavian flap angioplasty in neonates and infants, with particular attention to growth of the hypoplastic arch. METHODS: A retrospective analysis of 185 consecutive patients who underwent subclavian flap angioplasty between 1974 and 1998 was carried out. The patients included 125 neonates and 60 infants, with a median age of 18 days. Sixty-six (36%) patients had an additional ventricular septal defect, 41 (22%) patients had aortic arch hypoplasia diagnosed preoperatively, 141 (76%) had an associated patent ductus arteriosus, and 41 (22%) had additional complex heart disease. Follow-up was with transthoracic Doppler echocardiography in all patients. RESULTS: The early mortality was 3%. Recoarctation, defined as a Doppler gradient of 25 mm Hg or more, occurred in 11 (6%) patients at a median follow-up of 6.2 years (6.2 +/- 4.6 years). This included 4 of the 41 patients in whom arch hypoplasia was diagnosed preoperatively. There were no complications with the left arm. By multivariate analysis, risk factors for death were determined to be residual arch hypoplasia and low birth weight. The only risk factor for recoarctation was persistent arch hypoplasia after surgical treatment. However, angiographic imaging of the aorta showed that recoarctation was not due to a hypoplastic transverse arch, and it was probably at the site of ductal tissue. Survival at 5 and 10 years was 98% and 96%, respectively. Freedom from reoperation for recoarctation at 2 years was 95%, and at 5, 10, and 15 years, it was 92%. CONCLUSIONS: Subclavian flap repair remains an effective technique for repair of aortic coarctation with excellent results and low mortality. In the majority of patients, arch hypoplasia regresses after this procedure.
BACKGROUND: Postoperative pulmonary hypertension in children after congenital heart surgery is a risk factor for death and is associated with severe acute changes in both pulmonary vascular resistance and lung mechanics. OBJECTIVE: To examine the impact of changes in pulmonary blood flow on lung mechanics in preoperative children with congenital heart disease, in order to assess the cause-effect relation of pulmonary vascular-bronchial interactions. DESIGN: Prospective, cross sectional study. SETTING: Cardiac catheterisation laboratory, general anaesthesia with mechanical ventilation. INTERVENTIONS: Variation of pulmonary blood flow (Qp) by either balloon occlusion of an atrial septal defect before interventional closure, or by complete occlusion of the pulmonary artery during balloon pulmonary valvuloplasty for pulmonary valve stenosis. MAIN OUTCOME MEASURES: Ventilatory tidal volume (Vt), dynamic respiratory system compliance (Cdyn), respiratory system resistance (Rrs). RESULTS: 28 occlusions were examined in nine patients with atrial septal defect (median age 9.5 years) and 22 in eight patients with pulmonary stenosis (median age 1.2 years). Normalisation of Qp during balloon occlusion of atrial septal defect caused no significant change in airway pressures and Rrs, but there was a small decrease in Vt (mean (SD): 9.61 (0.85) to 9.52 (0.97) ml/kg; p < 0.05) and Cdyn (0.64 (0.11) to 0.59 (0.10) ml/cm H(2)O*kg; p < 0.01). These changes were more pronounced when there was complete cessation of Qp during balloon valvuloplasty in pulmonary stenosis, with a fall in Vt (9.71 (2.95) to 9.32 (2.84) ml/kg; p < 0.05) and Cdyn (0.72 (0.29) to 0.64 (0.26) ml/cm H(2)O*kg; p < 0.001), and there was also an increase in Rrs (25.1 (1. 7) to 28.8 (1.6) cm H(2)O/litre*s; p < 0.01). All these changes exceeded the variability of the baseline measurements more than threefold. CONCLUSIONS: Acute changes in pulmonary blood flow are associated with simultaneous changes in lung mechanics. While these changes are small they may represent a valid model to explain the pathophysiological impact of spontaneous changes in pulmonary blood flow in clinically more critical situations in children with congenital heart disease.
BACKGROUND: The increase in pulmonary vascular resistance (PVR) seen in children after cardiopulmonary bypass has been attributed to transient pulmonary endothelial dysfunction (PED). We therefore examined PED in children with congenital heart disease by assessing the L-arginine-nitric oxide (NO) pathway in terms of substrate supplementation (L-arginine [L-Arg]), stimulation of endogenous NO release (substance P [Sub-P]), and end-product provision (inhaled NO) before and after open heart surgery. METHODS AND RESULTS: Ten patients (aged 0.62+/-0.27 years) with pulmonary hypertension undergoing cardiac catheterization who had not had surgery and 10 patients (aged 0.65+/-0.73 years) who had recently undergone cardiopulmonary bypass were examined. All were sedated and paralyzed and received positive-pressure ventilation. Blood samples and pressure measurements were taken from catheters in the pulmonary artery and the pulmonary vein or left atrium. Respiratory mass spectrometry was used to measure oxygen uptake, and cardiac output was determined by the direct Fick method. PVR was calculated during steady state at ventilation with room air, during FIO(2) of 0.65, then during additional intravenous infusion of L-Arg (15 mg. kg(-1). min(-1)) and Sub-P (1 pmol. kg(-1). min(-1)), and finally during inhalation of NO (20 ppm). In preoperative patients, the lack of an additional significant change of PVR with L-Arg, Sub-P, and inhaled NO suggests little preexisting PED. Postoperative PVR was higher, with an additional pulmonary endothelial contribution that was restorable with L-Arg and Sub-P. CONCLUSIONS: Postoperatively, the rise in PVR suggested PED, which was restorable by L-Arg and Sub-P, with no additional effect of inhaled NO. These results may indicate important new treatment strategies for these patients.
OBJECTIVE: Our goal was to establish the morphologic nature of the obstructive muscular lesions in double-chambered right ventricle. METHODS: We based our morphologic observations on 10 normal hearts and on the surgical findings in 26 patients, aged 0.5 to 24 years, with a mean of 6.9 years (SD 5.8 years). In the normal hearts, we measured the distance from the pulmonary valve to the apex of the right ventricle and from the takeoff of the moderator band to the ventricular apex. From angiograms available in 20 patients, using the frontal view, we then measured the distance from the pulmonary valve to the apex of the right ventricle and from the midpoint of the obstructive lesion to the apex of the right ventricle. This permitted calculations of multiple ratios. RESULTS: In the 10 normal hearts, the moderator band took origin at a mean ratio of 0.48 (SD 0.16) of the ventricular length. On the basis of the angiographic findings, we identified 2 basic forms of double-chambered right ventricle. In 9 patients, the obstructive muscular shelf was positioned low and diagonally across the apical component, with a mean ratio of 0.38 relative to the ventricular length (SD 0.02). In the other 11 patients, the obstructive shelf was high and horizontal, with a mean ratio of 0.27 (SD 0.02). The difference was statistically significant (P =.001). Surgical repair was performed successfully in all 26 patients through a right ventriculotomy. CONCLUSIONS: Double-chambered right ventricle is the consequence of a high or low muscular division of the apical component of the right ventricle. The abnormal muscular bundle probably represents accentuated septoparietal trabeculations, rather than always being an abnormal moderator band.
OBJECTIVE: To study patients with atrioventricular septal defect to determine the pathognomonic morphological features of the lesion and the relation between the septal structures and the atrioventricular junction. Setting : Tertiary level paediatric cardiology centre. METHODS: Cross sectional echocardiograms from 60 patients were reviewed using qualitative and quantitative analysis. The unifying feature was the presence of a common atrioventricular junction. The overall dimensions of the septal defect were determined and related to the plane of the common junction; the extent of both the atrial and the ventricular septal components was then measured according to the site of closure of the bridging leaflets. RESULTS: In 48 cases, the common junction was guarded by a common valvar orifice, but in 12 cases there were separate right and left valvar orifices. Irrespective of the valvar morphology, no significant difference was found between the groups in terms of the dimensions of the atrial and ventricular septal components. In all patients, the hole permitting shunting at atrial level extended below the plane of the atrioventricular junction, with a variable position of the leading edge of the atrial septum itself. CONCLUSIONS: The atrioventricular junction is a common structure irrespective of valvar morphology. In spite of the presence of unequivocal shunting at atrial level, the atrial septum is usually a well formed structure, even extending in some below the level of the common atrioventricular junction.
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OBJECTIVE: To evaluate the feasibility of anatomical correction based on morphological and echocardiographic findings in patients and preserved hearts with discordant atrioventricular connections. DESIGN: A retrospective study with clinicomorphological correlations to assess potential contraindications for anatomical correction in the setting of discordant atrioventricular connections. SETTING: A tertiary referral centre for congenital heart disease. MATERIAL: 25 specimens and 53 patients unified by presence of discordant atrioventricular connections. METHODS: The potential contraindications for anatomical correction were first evaluated on the basis of morphological findings in all 25 specimens with discordant atrioventricular connections collected in the department museum, including study of the major coronary arterial patterns in 20. These contraindications were then sought in a population of 53 patients examined echocardiographically between January 1992 and October 1997. RESULTS: At least one lesion was discovered that might have contraindicated anatomical correction in 14 of the specimens and in 16 of the patients. The most common lesions that might militate against the anatomical approach were severe Ebstein's malformation or straddling and overriding of the tricuspid valve, each when combined with hypoplasia of the morphologically right ventricle. Other potential contraindications were atrioventricular septal defect with common atrioventricular junction, and obstruction of the left ventricular outlet combined with a restrictive ventricular septal defect, although these may be overcome with increasing experience and expertise. CONCLUSIONS: According to the morphological and echocardiographic findings, at least 10 hearts and 37 patients would have produced no anatomical problems for the type of surgical correction in which the morphologically left ventricle is restored its rightful role as the systemic pumping chamber.
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Percutaneous balloon valvuloplasty is now a widely accepted alternative to surgical valvotomy for patients with congenital aortic valve stenosis. Mitral valve anomalies are well known to coexist and influence the prognosis from all palliative procedures. Two cases of mitral valve injury occurring during balloon aortic valvuloplasty are reported, one an 11 month old boy, the other a 2 day old baby boy. Both cases were characterised by an unusually posterior position of the guidewire, over which the balloon was deployed. The wire, and hence the balloon, may have been placed through the tension apparatus of the mitral valve with subsequent damage to its free edge on inflation. This is at least conceptually more likely to occur if the orifice of the valve is posterior, if there is a small left ventricular cavity, or if the mitral valve itself is abnormal-features present in both cases. Possible strategies for decreasing the incidence of such damage are considered.
OBJECTIVE: To assess the workload of, and referral patterns to, paediatric cardiology outreach clinics to provide data for future planning. DESIGN: Descriptive study of outpatient attendance during 1991 and 1996. SETTING: Five district general hospitals with unchanged local demographics and referral patterns during the study period. METHODS: Postal, telephone, and on site survey of clinic records and case notes. RESULTS: The number of outpatients increased by 61%, with a consequent increase in the number of clinics held and patients seen in each clinic. The number of patients aged between 10 and 15 years doubled. CONCLUSION: These data confirm the impression that demands for paediatric cardiology services are increasing. The increased need for attendance at outreach clinics has inevitable consequences for the clinical, teaching, and research activities of specialists in tertiary centres. An increase in the number of paediatric cardiologists, or development of local expertise (general paediatricians with an interest in cardiology), will be required. Furthermore, the increasingly large cohort of older teenagers and young adults with congenital heart disease underscores the need for the development of specialist facilities.
Aorto-pulmonary window (aorto-pulmonary septal defect) is an uncommon congenital cardiac malformation which is repaired using cardiopulmonary bypass. A case is described of an infant with a small aorto-pulmonary window which was closed by transcatheter insertion of a double umbrella device. Complete occlusion of the defect was achieved without complications. Transcatheter umbrella closure of a small aorto-pulmonary window is feasible in infancy and the technique is likely to be applicable in a few cases.
BACKGROUND: The diagnosis of sinus venosus defects remains a matter of debate. It is crucial to provide solid anatomical criteria, by identifying the very nature of the atrial septum relative to sinus venosus defects, to diagnose and differentiate them from other interatrial communications. OBJECTIVE: This study was designed to reestablish the anatomical criteria for the diagnosis of sinus venosus defects. METHODS: Five specimens with sinus venosus defects from the cardiopathological museum were examined. Study of the abnormal hearts was supplemented by examining the extent and structure of the atrial septum in 10 normal hearts. The echocardiograms and surgical notes were reviewed from 18 patients seen between July 1991 and August 1996 at the Royal Brompton Hospital in London diagnosed preoperatively to have a sinus venosus defect. RESULTS: The nature of the oval fossa and its muscular borders were identified in the normal hearts. In all three autopsied specimens of the superior variety of sinus venosus defect, the mouth of the superior caval vein was overriding the intact muscular anterosuperior border of the oval fossa. Two specimens thought initially to have the inferior variety of sinus venosus defect were re-classified as having defects within the oval fossa as it was the deficient oval fossa itself, rather than its intact muscular border, that was overridden by the mouth of the inferior caval vein. Sixteen patients had been diagnosed echocardiographically as exhibiting the superior variant of the defect. Retrospective review showed overriding of the superior caval vein across the upper rim of the oval fossa in 12 patients. These findings were confirmed by surgery in 11 patients with the 12th awaiting operation. Overriding of the fossa by the caval vein was not found in the other four patients. Surgery in all of these showed the defect to be within the oval fossa. In two patients diagnosed echocardiographically as having inferior defects, the surgical findings confirmed a biatrial connection of the inferior caval vein in one patient, the findings in the second were equivocal. CONCLUSIONS: The key anatomical criterion for the diagnosis of sinus venosus defects is overriding of the mouth of the superior or inferior caval vein across the intact muscular border of the oval fossa. The interatrial communication is then formed within the mouth of the overriding vein, and is outside the confines of the oval fossa.