Waveguide-integrated silicon T centres.

The performance of modular, networked quantum technologies will be strongly dependent upon the quality of their quantum light-matter interconnects. Solid-state colour centres, and in particular T centres in silicon, offer competitive technological and commercial advantages as the basis for quantum networking technologies and distributed quantum computing. These newly rediscovered silicon defects offer direct telecommunications-band photonic emission, long-lived electron and nuclear spin qubits, and proven native integration into industry-standard, CMOS-compatible, silicon-on-insulator (SOI) photonic chips at scale. Here we demonstrate further levels of integration by characterizing T centre spin ensembles in single-mode waveguides in SOI. In addition to measuring long spin T1 times, we report on the integrated centres' optical properties. We find that the narrow homogeneous linewidth of these waveguide-integrated emitters is already sufficiently low to predict the future success of remote spin-entangling protocols with only modest cavity Purcell enhancements. We show that further improvements may still be possible by measuring nearly lifetime-limited homogeneous linewidths in isotopically pure bulk crystals. In each case the measured linewidths are more than an order of magnitude lower than previously reported and further support the view that high-performance, large-scale distributed quantum technologies based upon T centres in silicon may be attainable in the near term.

Using a standardised protocol was effective in reducing hospitalisation and treatment use in children with newly diagnosed immune thrombocytopenia.

AIM: Childhood immune thrombocytopenia (ITP) has been associated with low bleeding rates and a high frequency of spontaneous remission. Although current guidelines suggest that most patients are just observed, children still receive platelet-enhancing therapies for fear of bleeding complications. We hypothesised that a standardised protocol with a step-down approach would reduce hospitalisation and treatment use. METHOD: A retrospective chart review was performed on patients diagnosed with acute ITP between January 2010 and December 2014, before (n = 54) and after (n = 37) the standardised protocol, which was introduced in January 2013. Management and events during the first 3 months following diagnosis were recorded. RESULTS: The protocol resulted in a 34% decrease in the hospitalisation rate (p < 0.001) at diagnosis. Prednisone treatment duration at diagnosis was also significantly reduced (13.1 versus 5.8 days, p = 0.004). Children over 3 years of age were 3.8 times less likely to be hospitalised (95% CI 1.94-7.61) and 2.3 times less likely to receive treatment (95% CI 1.2-4.3). There was no difference in the rate of persistent ITP (38% versus 30%, p = 0.43) or serious bleeding complications (7% versus 5%, p = 0.70). CONCLUSION: Our ITP management protocol significantly reduced hospitalisation rates and length of prednisone treatment without any increase in disease complications.

Immediate and short-term effects of pulmonary artery banding on left ventricular performance in foetal sheep.

AIM: To evaluate foetal left ventricular performance when its preload was increased by banding the pulmonary artery, a study design where a simultaneous change in left ventricular afterload is unlikely. METHODS: Nine ovine foetuses were studied with real-time images and Doppler echocardiography before, 3-4 and 6-8 d after surgery. Seven of these foetuses were also studied during the surgical intervention, immediately before and within 2 min after banding. RESULTS: The immediate effects of a 90-95% reduction of the pulmonary artery cross-sectional area were: a 53 +/- 20% (mean +/- SD) decrease and a 38 +/- 10% increase of right (RvQ) and left ventricular output (LvQ), respectively. Comparing measurements before and 3-4 d after operation, there was a 64 +/- 16% decrease of RvQ and a 64 +/- 25% increase of LvQ. The increase in LvQ was due to an increase in both heart rate (19 +/- 10%) and stroke volume (38 +/- 18%). After an additional 3-4 postoperative days, heart rate remained increased to the same extent, but there was a more pronounced increase of LvQ (93 +/- 19%) and stroke volume (59 +/- 22%). CONCLUSION: The parallel foetal circulation has a capacity to handle a severely increased afterload for the right ventricle by immediately improving and maintaining an increased left ventricular performance. This improvement was in part accomplished by an increase in stroke volume.

Regulation of murine survival motor neuron (Smn) protein levels by modifying Smn exon 7 splicing.

Proximal spinal muscular atrophy (SMA) is caused by mutations in the survival motor neuron gene (SMN1). In humans, two nearly identical copies of SMN exist and differ only by a single non-polymorphic C-->T nucleotide transition in exon 7. SMN1 contains a 'C' nucleotide at the +6 position of exon 7 and produces primarily full-length SMN transcripts, whereas SMN2 contains a 'T' nucleotide and produces high levels of a transcript that lacks exon 7 and a low level of full-length SMN transcripts. All SMA patients lack a functional SMN1 gene but retain at least one copy of SMN2, suggesting that the low level of full-length protein produced from SMN2 is sufficient for all cell types except motor neurons. The murine Smn gene is not duplicated or alternatively spliced. It resembles SMN1 in that the critical exon 7 +6 'C' nucleotide is conserved. We have generated Smn minigenes containing either wild-type Smn exon 7 or an altered exon 7 containing the C-->T nucleotide transition to mimic SMN2. When expressed in cultured cells or transgenic mice, the wild-type minigene produced only full-length transcripts whereas the modified minigene alternatively spliced exon 7. Furthermore, Smn exon 7 contains a critical AG-rich exonic splice enhancer sequence (ESE) analogous to the human ESE within SMN exon 7, and subtle mutations within the mESE caused a variation in Smn transcript levels. In summary, we show for the first time that the murine Smn locus can be induced to alternatively splice exon 7. These results demonstrate that SMN protein levels can be varied in the mouse by the introduction of specific mutations at the endogenous Smn locus and thereby lay the foundation for developing animals that closely 'resemble' SMA patients.

Generation of reactive O2 species in the myocardium of newborn lambs following intrauterine increase in right ventricular pressure.

Fetuses with pulmonary stenosis and constriction of the ductus arteriosus or the recipient twin in the context of a twin-to-twin transfusion syndrome may present with severe right ventricular myocardial dysfunction. Free O2 radicals are known to be increased in hypertrophied adult myocardium secondary to an increase in endocavitary pressure. This study investigates whether products of reactive O2 species generation are abnormally elevated in the myocardium of fetuses with increased right ventricular pressure. Banding of the main pulmonary artery was performed in five fetal lambs at 90 to 100 days of gestation. Three other animals had a sham intervention and were used as controls. Postoperative observation lasted on average 42 days (range 33-49 days). The levels of hydroperoxides were found to be significantly higher in the right ventricle of the stenosed lambs (6.6 +/- 3.5 nmol/mg protein) compared to the left ventricle of the same lambs (0.7 +/- 0.7 nmol/mg protein), and compared to the right (0.12 +/- 0.1 nmol/mg protein) and the left (0.5 +/- 0.8 nmol/mg protein) ventricles of the controls. It is concluded that during fetal life, an increase in right ventricular pressure is associated with a marked accumulation of products of reactive O2 species generation in the right ventricular myocardium.

[Growth and pubertal development following pediatric heart transplantation]. / Croissance et développement pubertaire après transplantation cardiaque pédiatrique.

STUDY AIM: Prospective study of growth and pubertal development following pediatric heart transplantation in 25 children. PATIENTS AND METHOD: Twenty-five children underwent orthotopic cardiac transplantation at Ste-Justine Hospital from July 1984 to August 1996. Systematic evaluation of anthropometric parameters (weight, height, bone age), hormonal profile (LH, FSH, testosterone, oestradiol, DHEAS), and pubertal development according to Marshall and Tanner were done yearly. RESULTS: Six patients had severe growth retardation at transplantation and only one patient was obese. All patients showed normal height increment following cardiac transplantation. Only 3 patients will not reach genetic target height. The 6 children suffering from congenital cardiomyopathy and showing severe growth delay before surgery did not show any significant catch up growth. Significant weight gain was observed during the first post-operative year (113 +/- 27% ideal body weight p = 0.0002) with evolution towards normal values at 2 years (100 +/- 18%). Thirteen patients were in the prepubertal stage at the time of transplant. Since then, one girl had her menarche at 11 years of age and 3 boys started their pubertal onset at 12 years old. The elevation of blood gonadotrophins during pubertal development correlated with progression of secondary sexual characteristics in both sexes. CONCLUSION: This pediatric population showed normal growth and normal onset and progression of puberty following cardiac transplantation. However, no catch-up growth was observed. The most important factor influencing attainment of maximal growth potential following heart transplantation was the degree of staturoponderal growth retardation at the time of surgery.

Growth and pubertal development following pediatric heart transplantation: a 15-year experience at Ste-Justine Hospital.

BACKGROUND: Thirty-one children and adolescents have undergone allograft heart transplantation at Ste-Justine Hospital from July 1984 to August 1996. Twenty-five patients were followed prospectively more than 3 years to document their growth and pubertal development. METHODS: Parameters surveyed were clinical (height, weight, pubertal staging, and bone age) and biochemical (luteinizing hormone (LH), follicle-stimulating hormone (FSH), testosterone, estradiol, dehydroepiandrosterone sulphate (DHEAS), IGF-1, and fasting insulin). RESULTS: At surgery, there were 18 boys and 7 girls aged 11 months to 17 years (median 13 years); 14 had congenital heart defects (CHDs) and 11 had a cardiomyopathy (CM). Immunosuppressive therapy included cyclosporine, azathioprine, and prednisone. Eighteen patients were still growing (15 boys, 3 girls): 8 had a retarded bone age and 6 with CHD had severe growth failure. Following surgery, most patients maintained their height within one sodium dodecyl sulfate (SDS) score of that initially observed. Patients reaching their target heights do so mainly in the lower range. Three patients not reaching target height had a CHD. Weight was greatest 1 year postoperatively (113 +/- 27% ideal body weight) with normalization at 2 years (100 +/- 18%). Of the 13 prepubertal patients, menarche occurred at age 12 in 1 girl, while 3 boys began puberty at age 12 years. In both sexes, serum levels of gonadotropins and IGF-1 increased during puberty, moderate hyperinsulinism was observed, and DHEAS levels decreased. CONCLUSIONS: Our results indicate that children and adolescents grow normally following cardiac transplantation and that they attain their target height despite a lack of catch-up growth. They gain weight significantly in the first postoperative year with normalization of their weight at 2 years. Furthermore, the clinical and biochemical indices of puberty are overall within the norms. However, the severity of growth delay at the time of transplantation inherent to the cardiac pathology has a major impact on adult height.

[Aortic valve stenosis in children. Surgical valvuloplasty long-term results]. / Sténose valvulaire aortique chez l'enfant. Résultats à long terme de la valvuloplastie chirurgicale.

From 1960 through 1992, 67 children with congenital aortic stenosis aged 6-228 months (M 105.7 +/- 52) were submitted to aortic valvuloplasty at our institution. There was no hospital mortality. During the follow-up of 127.5 +/- 66.7 months, there were two late valve related deaths. Eight patients (11.9%) developed aortic regurgitation 5 to 125 months (M 66.6 +/- 35) following surgical valvuloplasty and one of them required aortic valve replacement. Because of restenosis, 15 patients required a second operation. Of them five children underwent a second aortic valvuloplasty without mortality and, in four of them, the functional result has been excellent after a mean follow-up of 75.4 +/- 12 months. Ten patients required an aortic valve replacement 62 to 208 months post-op (M 100.9 +/- 50.8). Mechanical prosthesis were used in 6 and bioprosthesis in 4. Two patients required a Konno and one patient a Ross procedure. There were no early nor late deaths following reoperations. The 20 year survival rate following the first valvuloplasty was 94%, the freedom from reoperation 63% and the freedom from aortic valve replacement 73% for the same time period. Our results demonstrate that congenital aortic valvar stenosis in children can be surgically well controlled until adulthood. Our study also illustrates that surgical valvuloplasty is a safe and efficacious procedure and that its beneficial effect is maintained over 20 years in the majority of children.

[Ebstein's anomaly: valvular replacement in pediatric patients]. / Maladie d'Ebstein: remplacement valvulaire à l'âge pédiatrique.

The surgical treatment of Ebstein's anomaly is still controversial. Therefore we have retrospectively studied the results of tricuspid valve replacement (TVR) performed for this anomaly at Sainte Justine Hospital. From October 1977 to December 1997, 9 patients with Ebstein's anomaly, aged from 31 to 248 months (mean 176 +/- 66), have undergone TVR. Eight children were in functional class III or IV (NYHA), while one was in class II. Seven patients underwent plication of the atrialized right ventricular segment. Eight bioprostheses (ranging in diameter from 31 to 35 mm) and one mechanical prosthesis (21 mm) were used. The valve was implanted on the tricuspid annulus in six cases. There was no operative death, nor postoperative complete heart block. Follow-up ranged from 11 to 264 months (mean 91 +/- 84). One late death occurred unrelated to surgery. The probability of 20 years survival is 88%. One patient required a second TVR 162 months after the first surgery because of bioprosthesis failure. Seven of the surviving patients are in functional class I, while one patient is in class II. This experience suggests that TVR with bioprosthesis is a good therapeutical option for children with Ebstein's anomaly since the operative risk is low, the functional status improved in all patients and the durability of bioprosthesis in tricuspid position has been good.

Long-term results of surgical valvuloplasty for congenital valvar aortic stenosis in children.

BACKGROUND: To question the validity of surgical aortic valvuloplasty for congenital aortic valve stenosis, a retrospective study was undertaken to determine the long-term survival, the incidence of valve restenosis or insufficiency, and the freedom of reoperation or valve replacement. METHODS: From January 1960 through 1992, 67 consecutive children diagnosed with congenital aortic valve stenosis underwent an open aortic valvuloplasty at our institution. Ages at operation ranged from 6 to 228 months (mean 105.7 +/- 52 months). The mean follow-up of these patients has been 127.5 +/- 66.7 months. RESULTS: There was no hospital mortality, but two late valve-related deaths occurred. Eight patients developed aortic regurgitation 5 to 125 months (mean 66.6 +/- 35 months) after surgical valvuloplasty, and 1 of them required aortic valve replacement. Because of restenosis, 16 patients required a second operation. Of them, 5 children underwent a second aortic valvuloplasty without mortality and, in 4 of them, the functional result has been excellent after a mean follow-up of 75.4 +/- 12 months. Eleven patients required an aortic valve replacement 62 to 208 months postop (mean 100.9 +/- 50.8 months). Mechanical prosthesis were used in 7 and bioprosthesis in 4. Two patients required a Konno and 1 required a Ross procedure. There were no early nor late deaths after reoperations. The probability of 20-year survival after the first valvuloplasty was 94%, the freedom of reoperation 63%, and the freedom of aortic valve replacement 73% for the same time period. CONCLUSIONS: Our results demonstrate that congenital aortic valvar stenosis in children can be surgically well controlled until adulthood. Our study also shows that surgical valvuloplasty is a safe and efficacious procedure and that its beneficial effect is maintained over 20 years in the majority of children.

N-acetylcysteine in pig liver transplantation from non-heart-beating donors.

Lipid peroxidation due to oxygen free radicals (OFR) seems to play a major role in loss of liver graft viability after warm ischemia, preservation, and transplantation. N-acetylcysteine (NAC) is an antioxidant that has a direct effect on OFR, and is also a glutathione precursor, another antioxidant. This study was designed to evaluate the efficacy of NAC in preventing ischemia-reperfusion damage of liver grafts harvested from non-heart-beating donors. Liver transplantation was performed on pigs divided into five groups: group 1 (control group; n=5) received livers from heart-beating donors; livers were subjected to 30 min of warm ischemia in groups 2 (n=3, no NAC) and group 3 (n=3; NAC treatment); warm ischemia time lasted 60 min in groups 4 (n=4; no NAC) and 5 (n=5; NAC treatment). Studied parameters included graft survival for more than 3 days, aspartate aminotransferase plasma levels, liver histology, and hepatic total glutathione concentrations. Graft survival was 100% in groups 1, 2, and 3, 0% in group 4, and 20% in group 5. NAC treatment did not influence initial mean aspartate aminotransferase release which was greater in warm ischemic livers than in controls. NAC treatment had no effect on liver hepatic total glutathione after reperfusion of animals receiving warm ischemic grants. Finally, no effect on liver histology was observed with NAC treatment. Our study suggests that in liver transplantation from non-heart-beating donors, NAC has no effect in both graft viability and lipid peroxidation. The role of OFR in primary dysfunction of transplanted warm ischemic livers remains controversial.

Impact of research on pediatric pain assessment and outcomes.

PURPOSE: Pediatric nurses from varied practice and educational backgrounds learned about research by doing a ward-based study. The aim of the study was to determine if regular assessment of children's pain would improve their pain management and postoperative progress. METHOD: Children, ages 5 to 17 years (n = 36), measured their pain every 4 hours postoperatively using the Wong-Baker Faces Pain Rating Scale. Outcomes regarding amount of analgesic given, subjective pain reports, time and progress of ambulation, and length of hospital stay were compared with data from a retrospective chart-review of a control group (n = 50). FINDINGS: No statistically significant differences in these variables were found. An important clinical finding was that despite all children having prescribed PRN analgesic orders, one quarter of the children received no pain relief intervention. Also, one quarter of the children stated that their pain control was only partially effective. CONCLUSIONS: Study results reinforce findings reported in the literature regarding ineffective pain management in children, and highlight a need for improved nursing practice. Clinical significance was achieved in terms of staff learning of the research process, increased awareness of pediatric pain management practices, improved ward morale, and inter-agency sharing of resources.

Cardioprotective effects of diltiazem during acute rejection on heterotopic heart transplants.

In the presence of severe rejection, cardiac allograft perfusion has been shown to be impaired. Since a functionally reversible vasoconstrictor component has been identified in this condition and rejection does not reverse if ischemia does not, we hypothesized that diltiazem may be beneficial in this condition. Experiments were performed on dogs with heterotopic heart transplants and chronic instrumentation for the assessment of allograft perfusion. Two groups of cardiac allograft recipients were studied: untreated recipients and recipients treated with the calcium antagonist diltiazem (180 mg twice daily, orally). Allograft blood flow was monitored daily along with plasma diltiazem levels. The lymphoproliferative response to mitogens was studied at selected intervals until terminal rejection. Contractile function of the graft was assessed daily by palpation. Without immunosuppression, terminal rejection was observed within 7 days. Rejection was confirmed by histology; cellular infiltration and myocyte necrosis were present in all cardiac allografts but to a significantly lesser degree in diltiazem-treated recipients. The mean blood flow of heterotopically implanted hearts was in the range of 35-50 ml/min, which decreased steadily in untreated recipients. In contrast, significant improvement of allograft perfusion was observed in diltiazem-treated recipients at days 4-6 after transplantation. Diltiazem also significantly attenuated mitogen-induced lymphocyte proliferation at peak sensitivity (2 days after transplantation). Diltiazem plasma concentrations were in the therapeutic range (30-60 ng/ml) before and after cardiac transplantation. Results of the present study demonstrate beneficial effects of diltiazem in the course of severe cardiac rejection. Such findings support its use during rejection when maintenance of graft blood flow and myocyte protection may be important for myocardial function and viability.

Assessment of fetal pulmonic stenosis by ultrasonography.

This study was designed to determine (1) the value of Doppler echocardiography in depicting the presence of a fetal pulmonary stenosis, (2) its reliability in the assessment of the severity of the lesion, and (3) the usefulness of additional markers from the left side of the heart as criteria of severity. Fourteen pregnant ewes were included in this study (gestational age, 90 to 120 days). Banding of the fetal main pulmonary artery created mild (n = 3), moderate (n = 3), and severe (n = 5) stenosis. Three lambs were sham operated. Intrauterine fetal Doppler echocardiographic data obtained 15 days after surgery were compared with preoperative values. Peak velocities recorded through the band increased linearly from baseline in the groups with mild and moderate stenosis but did not show any further increase in the group with severe stenosis. Compared with the sham-operated group, right ventricular output in the group with stenosis was either similar or reduced significantly. The increase in right ventricular free wall thickness was significantly greater in the groups with stenosis compared with that of the sham-operated group; the correlation with the degree of severity was r = 0.65 and p < 0.05. A A stronger positive correlation was found between the severity of stenosis and aortic valve diameters: r = 0.82 and p < 0.01. The strongest correlation was found for right ventricular/left ventricular outputs (r = 0.92; p < 0.001). Thus Doppler peak velocities through the obstruction can help detect pulmonic stenosis but are not reliable for the assessment of its severity during fetal life. Other ultrasound measurements such as the size of the aortic anulus and especially the ratio of right ventricular/left ventricular output could be used as sensitive markers of the severity of stenosis.

Succinyl CoA: 3-oxoacid CoA transferase (SCOT): human cDNA cloning, human chromosomal mapping to 5p13, and mutation detection in a SCOT-deficient patient.

Succinyl CoA: 3-oxoacid CoA transferase (SCOT; E.C.2.8.3.5) mediates the rate-determining step of ketolysis in extrahepatic tissues, the esterification of acetoacetate to CoA for use in energy production. Hereditary SCOT deficiency in humans causes episodes of severe ketoacidosis. We obtained human-heart SCOT cDNA clones spanning the entire 1,560-nt coding sequence. Sequence alignment of the human SCOT peptides with other known CoA transferases revealed several conserved regions of potential functional importance. A single approximately 3.2-kb SCOT mRNA is present in human tissues (heart > leukocytes >> fibroblasts), but no signal is detectable in the human hepatoma cell line HepG2. We mapped the human SCOT locus (OXCT) to the cytogenetic band 5p13 by in situ hybridization. From fibroblasts of a patient with hereditary SCOT deficiency, we amplified and cloned cDNA fragments containing the entire SCOT coding sequence. We found a homozygous C-to-G transversion at nt 848, which changes the Ser 283 codon to a stop codon. This mutation (S283X) is incompatible with normal enzyme function and represents the first documentation of a pathogenic mutation in SCOT deficiency.

[Pubertal development after pediatric heart transplantation]. / Développement pubertaire après la greffe cardiaque pédiatrique.

Twenty-one children and adolescents underwent orthotopic cardiac transplantation at the Hôpital Sainte-Justine between July 1984 and June 1993. Of those patients, 16 (4 girls and 12 boys) who survived more than one year after the procedure were followed prospectively for documentation of onset and progression of puberty. The immunosuppressive therapy included cyclosporine, azathioprine and prednisone. Subjects were evaluated at 6 month intervals for the study of: pubertal development according to staging by the method of Marshall and Tanner and hormonal profile (FSH, LH, testosterone, DHEAS). Despite a stagnation of pubertal signs before surgery, puberty carried on and progressed normally postoperatively. The urinary levels of gonadotropins rose to adequate levels for age. Testosterone levels in boys were related to the progression of secondary sexual characteristics. Levels of DHEAS were drastically reduced, most likely because of the supraphysiological doses of oral glucocorticoids. Our results indicate that after pediatric heart transplantation, puberty progresses normally at adolescence.

[Pulmonary valve replacement in children]. / Remplacement valvulaire pulmonaire chez l'enfant.

From February 1988 to October 1994, 15 pulmonary valve replacements (PVR) have been performed at St-Justine Hospital in children with a mean age of 145.7 months. Ten children previously had a correction of tetralogy of Fallot; two had absent pulmonary valve syndrome; one had been operated on for pulmonary atresia with intact ventricular septum, one other had a correction for a ventricular septal defect with pulmonary artery banding; the last patient developed degeneration of a pulmonary bioprosthesis. The time between the primary repair and the PVR ranged from 61 to 221 months. Fourteen bioprosthesis and one aortic homograft were implanted. All patients had antiplatelet treatment. There was one operative death due to a fatal anaphylactic reaction and one late death occurred unrelated to valvular surgery. At follow-up from 1 to 187 months (mean, 40.7 months) all patients were in New York Heart Association Class 1. No hemorrhagic nor thromboembolic complication have been observed and no reoperation for bioprosthesis failure was necessary. Nevertheless in subsequent echocardiographic studies, two patients with the smallest bioprosthesis (21 mm) have developed pulmonary gradients of 80 and 85 mmHg, 65 and 80 months following PVR. While our results with PVR in children have been satisfactory, this operation should be performed only in symptomatic patients with severe pulmonary regurgitation because of progressive deterioration of the available bioprosthesis.

[Aortic valve replacement in children]. / Remplacement valvulaire aortique chez l'enfant.

From January 1970 to January 1993, 47 aortic valve replacements have been performed in children aged 166.8 +/- 50 months. The valvular pathology was congenital in 39 patients and associated cardiac anomalies were present in 31 cases. 30 children had a previous surgical procedure on the aortic outflow. Seven bioprosthesis and 40 mechanical valves have been implanted. At the time of surgery, an additional major cardiac correction has been performed on 17 occasions (Konno, Bentall, Fontan, correction of truncus arteriosus etc.). While no death occurred in the group subjected only to aortic valve replacement, 7 of the 17 patients where a major cardiac procedure was added died. During a mean follow-up of 61.2 +/- 59.1 months, 3 late deaths occurred, 2 of them non related to valvular surgery. Three reoperations have been performed, in two instances for replacing a degenerated bioprosthesis. One thromboembolic event occurred as well as one temporary episode of haemolytic anaemia. No haemorrhagic complication has been observed. While the results of isolated aortic valve replacement in children are excellent, the risk for hospital death is increased substantially when a major cardiovascular procedure is added to valve replacement, and because of rapid deterioration, the heterografts are now contra-indicated in children.