Re-evaluation of hypoplastic left heart syndrome from a developmental and morphological perspective.

BACKGROUND: Hypoplastic left heart syndrome (HLHS) covers a spectrum of rare congenital anomalies characterised by a non-apex forming left ventricle and stenosis/atresia of the mitral and aortic valves. Despite many studies, the causes of HLHS remain unclear and there are conflicting views regarding the role of flow, valvar or myocardial abnormalities in its pathogenesis, all of which were proposed prior to the description of the second heart field. Our aim was to re-evaluate the patterns of malformation in HLHS in relation to recognised cardiac progenitor populations, with a view to providing aetiologically useful sub-groupings for genomic studies. RESULTS: We examined 78 hearts previously classified as HLHS, with subtypes based on valve patency, and re-categorised them based on their objective ventricular phenotype. Three distinct subgroups could be identified: slit-like left ventricle (24%); miniaturised left ventricle (6%); and thickened left ventricle with endocardial fibroelastosis (EFE; 70%). Slit-like ventricles were always found in combination with aortic atresia and mitral atresia. Miniaturised left ventricles all had normally formed, though smaller aortic and mitral valves. The remaining group were found to have a range of aortic valve malformations associated with thickened left ventricular walls despite being described as either atresia or stenosis. The degree of myocardial thickening was not correlated to the degree of valvar stenosis. Lineage tracing in mice to investigate the progenitor populations that form the parts of the heart disrupted by HLHS showed that whereas Nkx2-5-Cre labelled myocardial and endothelial cells within the left and right ventricles, Mef2c-AHF-Cre, which labels second heart field-derived cells only, was largely restricted to the endocardium and myocardium of the right ventricle. However, like Nkx2-5-Cre, Mef2c-AHF-Cre lineage cells made a significant contribution to the aortic and mitral valves. In contrast, Wnt1-Cre made a major contribution only to the aortic valve. This suggests that discrete cardiac progenitors might be responsible for the patterns of defects observed in the distinct ventricular sub-groups. CONCLUSIONS: Only the slit-like ventricle grouping was found to map to the current nomenclature: the combination of mitral atresia with aortic atresia. It appears that slit-like and miniature ventricles also form discrete sub-groups. Thus, reclassification of HLHS into subgroups based on ventricular phenotype, might be useful in genetic and developmental studies in investigating the aetiology of this severe malformation syndrome.

Antenatal perspective of hypoplastic left heart syndrome: 5 years on.

BACKGROUND: Palliative staged reconstructive surgery has radically altered the outcome of babies with hypoplastic left heart syndrome (HLHS). AIM: To compare the current outcome of antenatally diagnosed HLHS with a series 5 years previously now that paediatric cardiothoracic and postnatal paediatric intensive care techniques have been further refined. METHOD: Comparison of all cases of HLHS diagnosed antenatally at Birmingham Women's Hospital between 1 January 2000 and 31 December 2004 with results of the previous series. RESULTS: 79 fetuses were identified with HLHS. The median gestational age at diagnosis was 22 weeks. After counselling, 20 (25.3%) couples terminated the pregnancy compared with 43.7% in the previous cohort (p = 0.01). Of the 59 couples who continued with the pregnancy, four had stillbirths and two were lost to follow-up. Subsequently, there were 53 live births, of which six babies had an alternative major congenital heart disease diagnosed postnatally; 10 babies were not considered for surgery (parents' wishes) and died after compassionate care; 31 babies underwent surgery. The early (30 days) surgical mortality after stage 1 Norwood procedure was 19.4% and 20 patients are still alive. In the cohort of intention-to-treat cases, the overall survival was 46.9% (23/49). CONCLUSION: The number of parents choosing termination after an antenatal diagnosis of HLHS has almost halved since 5 years ago. Despite the significant increase in surgical survival following stage 1 Norwood in this period, in the intention-to-treat cohort the survival was 46.9%. These data again highlight the poorer outcome for babies with congenital malformations diagnosed in utero in comparison with those identified postnatally.

Staged surgical management of hypoplastic left heart syndrome: a single institution 12 year experience.

OBJECTIVE: To describe a 12 year experience with staged surgical management of the hypoplastic left heart syndrome (HLHS) and to identify the factors that influenced outcome. METHODS: Between December 1992 and June 2004, 333 patients with HLHS underwent a Norwood procedure (median age 4 days, range 0-217 days). Subsequently 203 patients underwent a bidirectional Glenn procedure (stage II) and 81 patients underwent a modified Fontan procedure (stage III). Follow up was complete (median interval 3.7 years, range 32 days to 11.3 years). RESULTS: Early mortality after the Norwood procedure was 29% (n = 95); this decreased from 46% (first year) to 16% (last year; p < 0.05). Between stages, 49 patients died, 27 before stage II and 22 between stages II and III. There were one early and three late deaths after stage III. Actuarial survival (SEM) was 58% (3%) at one year and 50% (3%) at five and 10 years. On multivariable analysis, five factors influenced early mortality after the Norwood procedure (p < 0.05). Pulmonary blood flow supplied by a right ventricle to pulmonary artery (RV-PA) conduit, arch reconstruction with pulmonary homograft patch, and increased operative weight improved early mortality. Increased periods of cardiopulmonary bypass and deep hypothermic circulatory arrest increased early mortality. Similar factors also influenced actuarial survival after the Norwood procedure. CONCLUSION: This study identified an improvement in outcome after staged surgical management of HLHS, which was primarily attributable to changes in surgical technique. The RV-PA conduit, in particular, was associated with a notable and independent improvement in early and actuarial survival.

A forgotten old disease: mediastinal tuberculous lymphadenitis in children.

OBJECTIVE: The purpose of the study was two-fold: (1) to highlight the varied presentation of mediastinal tuberculous lymphadenitis (MTL) in children and (2) to identify parameters, that may help in the early diagnosis of this condition. METHODS: Between January 1995 and December 2002, 13 children with histological diagnosis of MTL were retrospectively assessed for age at presentation, history of exposure to TB, presenting symptoms, investigations, initial diagnosis, surgical treatment and outcome. Stepwise multiple linear regression analysis was used to determine potential risk factors for early diagnosis of MTL. RESULTS: Thirteen children presented with: (a) fever, night sweats and weight loss (4); (b) acute respiratory distress (2); (c) cough and shortness of breath (SOB) (5); (d) stridor (1); and (e) chest pain (1). TB was suspected only in 6 children (46%) at presentation. In the other 7 cases (54%) the presumed diagnoses were: neuroblastoma (n=1), metastatic malignancy (n=1), bronchial polyp (n=1), bronchogenic cyst (n=2), and presumed foreign body (n=2). Bronchoscopy was diagnostic in identifying cheesy material within the bronchus and organisms on lavage in 4 (30%) and in identifying external compression in 2 (15%). Thoracotomy and excision of the lymph node mass was necessary to treat the mediastinal compression and to ascertain the diagnosis of TB in 3 children (23%). All 13 children had complete resolution of tuberculous lymphadenitis following anti-tuberculous treatment. The diagnostic clues in this cohort of patients were cough and SOB with history of exposure to tuberculosis (P=0.0001) and bronchoscopy and lavage with positive staining for acid-fast bacilli (P=0.0001). CONCLUSIONS: Tuberculosis was not suspected in 54% of children with MTL, and they posed diagnostic dilemma on admission. Bronchoscopy must be used as a diagnostic tool in children where tuberculosis cannot be excluded by radiology or specific skin tests. Thoracotomy and excision may be necessary to treat the obstructive symptoms.

Changing practice of cardiac surgery in adult patients with congenital heart disease.

OBJECTIVES: To review 13 years' data from a unit for grown ups with congenital heart disease (GUCH) to understand the change in surgical practice. METHODS: Records were reviewed of patients over 16 years of age undergoing surgery between 1 January 1990 and 31 December 2002 in a dedicated GUCH unit. Patients with atrial septal defects were included but not those with Marfan's syndrome or undergoing a first procedure for bicuspid aortic valves. Three equal time periods of 52 months were analysed. RESULTS: Of 474 operations performed, 162 (34.2%) were repeat operations. The percentage of repeat operations increased from 24.8% (41 of 165) in January 1990-April 1994 to 49.7% (74 of 149) in September 1998-December 2002. Mortality was 6.3% (n = 30). The median age decreased from 25.4 years (interquartile range 18.7) in January 1990-April 1994 to 23.9 (interquartile range 17.3) in September 1998-December 2002 (p = 0.04). The proportion of patients with a "simple" diagnosis decreased from 45.4% (74 or 165) in January 1990-April 1994 to 27.5% (41 of 149) in September 1998-December 2002 (p = 0.013). Pulmonary valve replacements in operated tetralogy of Fallot increased from one case in January 1990-April 1994 to 23 cases in September 1998-December 2002 and conduit replacement increased from five cases to 17. However, secundum atrial septal defect closures decreased from 35 cases to 14 (p < 0.0001). The estimated cost (not including salaries and prosthetics) incurred by an adult patient with congenital heart disease was pound2290 compared with pound2641 for a patient undergoing coronary artery bypass grafting. CONCLUSION: Despite the impact of interventional cardiology, the total number of surgical procedures remained unchanged. The complexity of the cases increased particularly with repeat surgery. Nevertheless, the patients do well with low mortality and the inpatient costs remain comparable with costs of surgery for acquired disease.

Challenges in paediatric perfusion.

In the last 50 years cardiopulmonary bypass has evolved dramatically, so that even the most complex heart lesions can be repaired successfully. However, we are aware that whilst survival may be excellent, organ damage, even though minor, particularly to the central nervous system is common. The next challenge in paediatric perfusion is to reduce this damage to a minimum.

Repair of truncus arteriosus: a considered approach to right ventricular outflow tract reconstruction.

OBJECTIVE: In repair of truncus arteriosus the accepted methods of establishing right ventricle (RV) to pulmonary artery (PA) continuity utilize an allograft or xenograft valved conduit. Alternatively, the PA confluence may be directly anastomosed to the RV with anterior patch augmentation, which may allow growth and delay or avoid subsequent RVOT obstruction. These methods of RVOT reconstruction were evaluated in infants undergoing truncus arteriosus repair. METHODS: A retrospective analysis of 61 infants undergoing repair of truncus arteriosus between November 1988 and June 2000 was performed. Median age was 34 days (range 1 day to 6.4 months). The patient cohort was subdivided into two groups (1) Valved conduit group: RV to PA continuity performed with a conduit in 38 patients using allograft (28) or xenograft (10). (2) Direct anastomosis group: direct RV-PA anastomosis performed in 23 patients, augmented anteriorly with monocusp (15) or simple pericardial patch (eight). RESULTS: There were eight hospital deaths (13%, 95% confidence limits 5--21%). Hospital mortality did not differ significantly between group 1 and 2 (three patients (8%) versus five patients (22%) respectively, P=0.23). By multivariate analysis, low operative weight (P=0.023), severe truncal regurgitation (P=0.022) and major coronary abnormalities (P=0.018), were independent risk factors for hospital death. Hospital survivors were followed-up from 1.3 months to 11.8 years (mean 4.2+/-3.4 years). There were eight late deaths with survival of 73+/-6% at 2 years and beyond. Survival was not influenced by method of RVOT reconstruction (Conduit versus direct RV-PA anastomosis, 2.76+/-7%, 63+/-10%, respectively, P=0.23). Freedom from surgical RVOT reintervention was 56+/-10% in group 1 and 89+/-10% in group 2 at 10 years (P=0.023). The use of a xenograft conduit was an independent risk factor for reintervention (P<0.001). CONCLUSIONS: In truncus arteriosus repair, RV to PA continuity established by a direct anastomosis was associated with a low incidence of surgical RVOT re-intervention. This technique has the potential for RVOT growth and may be a useful alternative when an appropriate allograft is unavailable, particularly in the neonate where the risk of pulmonary hypertension are lower.

Early results of right ventricular-pulmonary artery conduits in patients under 1 year of age.

OBJECTIVES: Management strategies for the repair of many complex heart defects require the implantation of a valved conduit between the right ventricle (RV) and the pulmonary artery (PA), often using aortic or pulmonary homograft valves. Their limited availability, however, has led to the development and use of new conduits. We retrospectively compared our experience with small homografts in patients of less than 1 year of age with the TissueMed bioprosthetic valved conduit. METHODS: From March 1994 to November 1997 29 patients in their first year of life underwent conduit implantation for complex heart defects. These were retrospectively reviewed in order to determine the incidence of death or conduit stenosis. Seventeen patients received homografts and 12 TissueMed conduits. RESULTS: Diagnoses and operative details including conduit size were similar in the two groups and in all cases complete repair of the underlying defect was carried out. Early post-operative mortality was 4/17 (23.5%) in the homograft group and 3/12 (25%) in the TissueMed group. Echo Doppler evaluation within 1 month of operation showed no right ventricular outflow tract (RVOT) obstruction in any of the survivors. In the TissueMed group 8/9 (77%) survivors have gone on to develop significant RVOT obstruction within 12 months of operation. There have been three late deaths in this group all related to severe RVOT obstruction. Two patients died during an attempt at balloon dilatation and one patient died of progressive right heart failure. Five patients had successful replacement of the TissueMed conduit. One child remains well with no evidence of RVOT obstruction. At operation to replace conduit, or at autopsy, the stenoses were related to the deposition of fibrous tissue at the anastomotic suture lines. In the homograft group none of the survivors developed RVOT obstruction during the first 12 months post-operatively. There was one late death (non-cardiac in origin) and one child is awaiting conduit replacement 40 months after initial implantation for obstruction. CONCLUSIONS: The homograft is a satisfactory conduit for re-establishment of RV-PA continuity in infancy. Further work needs to be undertaken in order to elucidate the mechanisms of early graft failure in bioprosthetic conduits if these are to be a suitable alternative for RV outflow reconstruction in infants.

Arterial switch operation after left ventricular retraining in the adult.

Retraining the morphological left ventricle in transposition of the great arteries has been successfully reported in infancy, while older age seems to be a contraindication. A 23-year-old woman with ¿S,D,D¿ transposition of the great arteries and ventricular septal defect developed severe right systemic ventricular dysfunction 22 years after Mustard procedure and ventricular septal defect closure. Hemodynamic investigation revealed moderate pulmonary hypertension and preserved left ventricular function. A pulmonary artery band was applied to obtain a left-right ventricular pressure ratio of 0.91. Her postoperative course was characterized by biventricular failure, treated effectively with inotropic support. Six months later, she underwent a Mustard baffle takedown and arterial switch procedure. Her postoperative course was uneventful. She was discharged home on postoperative day 15. At 24-months follow-up, she is in excellent clinical condition; echocardiographic evaluation shows good left ventricular function (ejection fraction: 0.69) with left ventricular volume within normal limits (70 ml/m2). Our experience demonstrates that, despite adult age, a staged arterial switch operation can be performed successfully in selected patients when left ventricular function is preserved.

Outcome after prenatal diagnosis of hypoplastic left-heart syndrome: a case series.

BACKGROUND: Traditionally, after prenatal diagnosis of hypoplastic left-heart syndrome (HLHS) couples have been offered termination of pregnancy or comfort care. Success of postnatal surgical options such as the Norwood procedure have been associated with survival of up to 60%. Whether survival is affected by the congenital anomaly being identified prenatally or postnatally remains uncertain. METHODS: We reviewed all cases of prenatally diagnosed HLHS referred to the Fetal Medicine Unit at Birmingham Women's Hospital over 6 years between 1994 and 1999. FINDINGS: 87 cases of HLHS were referred at a median gestational age (95% CI) of 23 (19-37) weeks. Of these, 53 (61%) chose prenatal karyotyping. The overall frequency of abnormal karyotype was found in seven of 59 cases (12%) and associated structural anomalies in 18 of 87 (21%). After counselling, 38 of 87 couples (44%) chose termination of pregnancy. Of the remaining 49 fetuses, 11 (23%) were not considered for postnatal surgery because of parental choice and they died after compassionate care. Of the 36 babies who had surgery postnatally, 12 survived (33%). We recorded a survival rate of 38% for the stage-1 Norwood procedure in the prenatally diagnosed HLHS in our centre. These data suggest that at the point of prenatal detection, the overall survival rate for fetuses with HLHS is 25% (if terminated pregnancies are excluded). INTERPRETATION: Fetal echocardiography allows early diagnosis of HLHS and gives clinicians the opportunity to triage this group dependent on prenatal findings, including karyotyping and the exclusion of other structural anomalies. These prospective data provide up-to-date information on the basis of which parents can make decisions.

Total anomalous pulmonary venous connection: outcome of surgical correction and management of recurrent venous obstruction.

OBJECTIVE: Total anomalous pulmonary venous connection (TAPVC) can be corrected with low mortality and good outcome. If complicated by pulmonary vein stenosis (PVS), either at presentation or secondary to the repair, the long-term outcome is compromised. We have evaluated an institutional experience with TAPVC, with particular regard to the evolving management of PVS. METHODS: Retrospective analysis of 85 consecutive patients with non-isomeric TAPVC undergoing surgical correction over a 10-year period (1988-1997). In addition, three patients were referred to us with secondary PVS, having had their primary procedure elsewhere. Attention was focused on incidence of PVS, and strategies for management. RESULTS: Median age at first operation was 33 days (range 1-533). Site of drainage was supracardiac (43/88), infracardiac (20/88), cardiac (17/88), and mixed (8/88). On presentation, 35% of patients were ventilated. Early mortality was 7% (6/85), with one late non-cardiac death. 82% of the original patients (70/85) are currently well at a median follow-up of 64 months (range 6-119). The incidence of PVS requiring intervention was 11% (9/85). Median time to PVS was 41 days. In these patients, 18 balloon angioplasties, four endovascular stent placements (in two patients), and a further 23 surgical procedures were performed. Of the nine patients undergoing re-intervention after initial surgery at our institution, five (56%) survived. Two of these have no residual obstruction and right ventricular pressure (RVP) < 50% systemic, two have unilateral obstruction and RVP < 50% systemic, and one has bilateral obstruction and RVP 80% systemic. Of the three patients referred to us with secondary PVS, two are alive and well, and one died early after the first re-operation. CONCLUSIONS: Intrinsic obstruction (endocardial sclerosis or thickening) is associated with worse prognosis and earlier re-intervention than extrinsic (anatomical) obstruction. We advocate an early, aggressive approach to the management of patients with TAPVC, especially in the presence of PVS. This complication is most appropriately managed by a combination of re-operation and repeated balloon dilation.

Divided left atrium in association with tricuspid atresia and discordant ventriculo-arterial connections.

Division of the morphologically left atrium is a rare abnormality, constituting around 0.1% of congenital heart disease. It may coexist with other cardiac abnormalities, and this association may obscure its recognition. We report an uncommon association with tricuspid atresia and discordant ventriculo-arterial connections, the latter dominating the clinical picture. Accurate diagnosis was made by transthoracic cross-sectional echocardiography, and the patient was referred to surgery without need for cardiac catheterisation.

The modified Norwood procedure for hypoplastic left heart syndrome: early to intermediate results of 120 patients with particular reference to aortic arch repair.

BACKGROUND: Classic first-stage Norwood repair of hypoplastic left heart syndrome uses a homograft patch enlargement to obtain an unobstructed aorta and coronary arteries. Because of possible disadvantages of the homograft, such as lack of growth, degeneration and calcification, and availability, we have tried to repair the aorta without patch supplementation. METHODS: Between February 1993 and September 1997, 120 patients, aged birth to 47 days (median 4 days) and weighing 1.7 to 4.4 kg (median 3.1 kg), underwent first-stage palliation for hypoplastic left heart syndrome. The diameter of the ascending aorta ranged from 1.5 to 8.0 mm (median 3.0 mm). Eight patients had an aberrant right subclavian artery arising from the descending thoracic aorta. In 95 patients (group I), all duct tissue was excised and the descending aorta was anastomosed to the aortic arch, which had been opened back into the ascending aorta. Then to this confluence was anastomosed the proximal main pulmonary artery. In the remaining 25 patients (group II), continuity of the aortic arch was maintained and the repair was performed with a Damus-Kaye-Stansel anastomosis. The size of the systemic-to-pulmonary shunt was 3 mm in 48 patients, 3.5 mm in 70, and 4.0 mm in 2. RESULTS: Circulatory arrest time ranged from 19 to 105 minutes (median 54 minutes). A homograft patch was necessary for the arch reconstruction in 18 patients (15%); 9 group I patients (10%) and 9 group II (36%) (P =.001). There were 82 hospital survivors (68%); 69 group I patients (73%) and 13 group II (52%) (P =.04), 71 patients without a patch (70%) and 11 with a patch (61%) (P >.2). By multiple logistic regression, the aberrant right subclavian artery was a significant risk factor for hospital death (P =.008). There were 6 late deaths. Sixteen of 71 patients (23%) who underwent second-stage palliation had a neoaortic arch obstruction develop, with a peak gradient greater than 10 mm Hg; 14 group I patients (23%) and 2 group II (22%) ( P >.2), 15 without a patch (23%) and 1 with a patch (17%) (P >.2). Overall survivals were 57% at 1 year and 55% at 2 years. CONCLUSION: The modified Norwood procedure for first-stage palliation of hypoplastic left heart syndrome is possible in the majority of patients without the use of exogenous materials and does not result in an increased incidence of neoaortic arch obstruction. Repair of the aorta without patch supplementation may improve the potential for long-term growth of the new aorta.

Intraoperative ultrasonographic troubleshooting after the arterial switch operation.

BACKGROUND: Less than perfect coronary artery translocation accounts for the majority of perioperative deaths after the arterial switch procedure for transposition of the great arteries. Some types of coronary arterial anatomy are associated with a higher risk of death. METHODS: Prospective epicardial ultrasound examination of all neonates with failing left ventricle or difficulty in weaning off cardiopulmonary bypass was performed after completion of the arterial switch operation during a 2-year period from March 1994 to February 1996. The aim was to identify any mechanical, and potentially remediable, factors accounting for ventricular failure. RESULTS: Four neonates fulfilling the above criteria were identified during a 2-year period when epicardial echocardiography was routinely applied. In 2 patients coronary arterial problems in the form of kinking of the proximal left coronary artery (1 patient) and extrinsic compression of the artery by the neo-pulmonary trunk (1 patient) were identified and successfully corrected. In 2 other patients, supravalvar aortic stenosis was recognized, leading to prompt revision. CONCLUSIONS: Epicardial echocardiography has an important "troubleshooting" role in the subgroup of patients with a suboptimal hemodynamic result after the arterial switch operation. Patients with unusual coronary anatomy should routinely be candidates for such studies.

Management and outcome of infants and children with right atrial isomerism.

OBJECTIVES: To assess the current results and outcome of surgery in infants and children with right atrial isomerism and complex congenital heart disease. SETTING: Tertiary referral centre. METHODS: 20 consecutive children with right atrial isomerism and complex congenital heart disease underwent surgery over a 6 year period between August 1987 and July 1993. The results and outcome were analysed according to age, presentation, and surgical procedures. RESULTS: Patients were divided into two groups depending on age at presentation and initial surgery: group A comprised 11 patients who required surgical intervention in the first month of life (mean age 5 days); and group B comprised nine patients who required initial surgical intervention after the first month of life (mean age 6.8 months). Seven (64%) of the 11 patients in group A had obstructed pulmonary venous drainage and ten (91%) had pulmonary atresia. There were seven early deaths (64%), including the five patients who required systemic to pulmonary artery shunt and simultaneous repair of obstructed pulmonary veins. The long-term survival rate in this group was 18% (two of 11). Pulmonary venous obstruction was present in two (22%) of the nine patients in group B and four (44%) had pulmonary atresia. There were no early deaths. One patient died after a second palliative procedure. There was one late sudden death. Four patients had a Fontan operation with no deaths. Two of the remaining three patients meet the Fontan criteria. The long-term survival rate in this group was 78% (seven of nine). CONCLUSIONS: Surgical management of patients with right atrial isomerism who have complex congenital heart disease carries a high mortality and remains palliative. The overall survival rate was 45% (nine of 20); 18% in patients requiring surgery in the first month of life (group A) and 78% in patients requiring surgery after the first month of life (group B) (P < 0.001). Of the total of 20 patients, nine were potential candidates for a Fontan operation. Seven of these have undergone a Fontan procedure with five survivors.