Prenatal diagnosis of Shone's syndrome: parental counseling and clinical outcome.

OBJECTIVE: To describe a series of fetuses diagnosed as having Shone's syndrome, which includes four cardiac defects and for which there is a wide variety of clinical presentations, surgical treatments and outcomes, and to discuss the counseling strategy. METHODS: We reviewed retrospectively the records of four babies who were suspected prenatally to have Shone's syndrome. RESULTS: The mean age at diagnosis was 27.5 (range, 22-35) weeks. A small left ventricle, mitral and aortic annulus and ascending aorta were detected in three cases. In three fetuses there was an abnormal mitral valve apparatus and in two fetuses a sub-aortic membrane was detected. Coarctation of the aorta was an impending diagnosis in three babies. Following counseling, all parents decided to continue the pregnancy to term. Echocardiographic evaluation was performed soon after birth. The mean mitral valve annulus diameter was 8.2 (range, 7-10) mm, and that of the aortic valve annulus was 6 (range, 5-7) mm. The aortic valve was bicuspid in all babies with an additional sub-aortic membrane in two babies. Doppler ultrasound examination revealed high-velocity flow through the mitral valve in three babies; two of them had a parachute mitral valve. Coarctation repair was performed in two babies during the first week of life. One patient underwent mitral valvuloplasty followed by later mitral valve replacement. All patients were alive after a mean of 7.8 (range, 3.3-10.5) years' follow-up. CONCLUSION: When counseling families regarding fetal Shone's syndrome, it is important to emphasize the wide variety of clinical presentations and possible outcomes. Differentiation between hypoplastic left ventricle and Shone's complex is crucial and may influence the physician's attitude, the presentation of the case to the family and the family's final decision.

Methemoglobinemia induced by refrigerated vegetable puree in conjunction with supraventricular tachycardia.

UNLABELLED: We report on a case of methemoglobinemia in conjunction with supraventricular tachycardia. A 6-mo-old infant was admitted to hospital with perioral cyanosis three hours after eating a refrigerated mixed-vegetable puree. The patient developed supraventricular tachycardia (SVT) and had a heart rate of 230 beats/min. The arrhythmia resolved spontaneously. A chemical analysis showed oxygen saturation of 85% and a methemoglobin level of 25%. The infant was treated with oxygen and referred to the Pediatric Intensive Care Unit. The patient had two additional short episodes of SVT, which were resolved spontaneously without treatment. She received oxygen for 8 h until the methemoglobin level dropped to 1%. CONCLUSION: Long-term storage of refrigerated vegetables can cause methemoglobinemia in infants. Methemoglobinemia can appear in conjunction with SVT, but it is also possible that in a child with a tendency to develop SVT, methemoglobinemia involved hypoxemia, which then triggers SVT.

The role of tissue plasminogen activator in the successful treatment of infected cardiac thrombus in children.

Infected cardiac thrombus is rare in children, with antibiotic or antifungal agents used as the first line of treatment. Persistence is an indication for surgical intervention. We describe two children who were treated successfully with a combination of antibiotic and antithrombotic agents. Use of antithrombotic agents promotes degeneration of fibrin, thus reducing the mass and facilitating the diffusion of the antibiotic and/or antifungal agents.

Acute dilated cardiomyopathy and central nervous system toxicity following propranolol intoxication.

OBJECTIVE: We report a case of a 16-year-old boy who developed central nervous system (CNS) depression and acute dilated cardiomyopathy following ingestion of 3200 mg of propranolol in a suicide attempt. Early echocardiographic findings were the only sign of cardiac toxicity. DESIGN: A case report. SETTING: Pediatric intensive care unit of a teaching hospital. RESULTS: This child developed significant acute dilated cardiomyopathy and severe CNS depression 2 hours after ingesting 3200 mg of propranolol. The child was treated with gastric lavage, activated charcoal, and mechanical ventilation. Following the echocardiographic findings, treatment with isoprenaline hydrochloride and glucagon were given intravenously. Echocardiographic examination 12 hours following treatment showed normal left ventricular size and function. No change in pulse rate or blood pressure was reported on admission and during his hospitalization. DISCUSSION: In the early stages of propranolol and other lipophilic beta-blocker intoxication, severe CNS depression can develop in the absence of clinical signs of cardiac toxicity. Early echocardiographic evaluation is important and may prevent delay in diagnosis and treatment of cardiac toxicity.

Intravenous and oral propafenone for treatment of tachycardia in infants and children: pharmacokinetics and clinical response.

To elucidate contribution of an active metabolite to overall clinical responses to propafenone, steady-state disposition of propafenone and its active metabolite and the clinical responses to treatment were examined in pediatric patients receiving intravenous or oral propafenone. There were more than ten-fold interindividual differences in apparent clearance, resulting in a wide range of the steady-state trough plasma concentrations of propafenone. The active metabolite, 5-hydroxypropafenone, was detected in four of the six patients receiving oral propafenone; however, two neonates receiving oral propafenone and all eight receiving intravenous propafenone had no detectable levels of 5-hydroxypropafenone in plasma. In nine patients for whom electrocardiographic (ECG) data were available, the PQ interval was significantly increased, whereas the QRS duration and the QTc interval were not. There was no close relationship between plasma concentrations of propafenone or 5-hydroxypropafenone and ECG parameters. Lack of good correlation between serum concentrations and clinical response precludes using a serum-concentration targeting strategy with propafenone therapy.

Pulmonary hypertension in respiratory distress syndrome.

Pulmonary hypertension was associated with nonresponse to surfactant in six premature infants with respiratory distress syndrome. The diagnosis was suspected on the basis of a discrepancy between the X-ray findings and the severity of the clinical status as reflected by hypoxia despite maximal ventilatory support. The diagnosis of pulmonary hypertension was made by pre- and postductal oxygen saturation differences or by echodoppler cardiography, showing suprasystemic right ventricular pressures or right to left shunts through a patent foramen ovale or the ductus arteriosus. The response to surfactant was quantified by the arterial/alveolar (a/A) ratio difference before and 1 hr after therapy ("delta a/A ratio"); the delta a/A ratio was 0 +/- 0.01, which indicates a nonresponse. A single dose of 1 mg/kg tolazoline was administrated and the response assessed by a/A difference. A delta a/A ratio of 0.11 +/- 0.11 (range 0.02-0.32) represented a dramatic response and enabled oxygenation in these severely ill infants. No significant side effects were observed. We conclude that pulmonary hypertension may be an important and reversible condition in certain cases of respiratory distress syndrome and has to be considered in infants who do not respond to surfactant.

Successful radiofrequency ablation in a 3-month-old baby with permanent junctional reciprocating tachycardia: a new era in the treatment of incessant life-threatening arrhythmias in infants.

We report our experience in treating a 3-month-old baby with accessory atrioventricular pathway by radiofrequency (RF) ablation. The baby was discovered to have incessant supraventricular tachycardia at 4 weeks of age. At that time, two-dimensional echocardiography showed dilated cardiomyopathy. Multiple direct current shocks and multipharmaceutical treatment failed to restore sinus rhythm. Electrophysiology study showed the presence of posteroseptal accessory pathway. Immediately after delivery of two RF pulses, successful ablation of the accessory pathway and complete atrioventricular (AV) block with good junctional escape rhythm were observed. Normal rhythm and AV conduction subsequently returned and all medical treatment was discontinued. To our best knowledge, this is the first case of successful treatment with RF ablation in early infancy.

Cardiac abnormalities in the Bardet-Biedl syndrome: echocardiographic studies of 22 patients.

The Bardet-Biedl syndrome is an autosomal recessive disorder of polydactyly, obesity, tapetoretinal degeneration, mental retardation, hypogenitalism, and renal involvement. A high incidence of congenital and acquired heart disease was reported in the former "Laurence-Moon-Biedl-Bardet" syndrome. However, since the establishment of the Bardet-Biedl syndrome as a separate clinical entity, cardiac involvement has not been evaluated in this disorder. We have performed echocardiographic studies on 22 patients with the Bardet-Biedl syndrome from three extended, highly inbred Bedouin families. In addition to previously reported congenital heart defects we have observed hypertrophy of the interventricular septum and dilated cardiomyopathy. Our findings of cardiac involvement in 50% of the cases suggest that echocardiographic examination should be included in the clinical evaluation and follow-up of patients with Bardet-Biedl syndrome.

Balloon dilation of pulmonary venous pathway obstruction in an infant after the mustard procedure.

Pulmonary venous pathway obstruction developed after a Mustard procedure in an infant with transposition of the great arteries. The stenosis was successfully dilated by the percutaneous balloon technique with immediate clinical, echocardiographic, and hemodynamic improvement, which has persisted for 8 months after dilation. This technique is a feasible alternative to reoperation in such an obstruction, even in infants.

Spectrum of cardiovascular anomalies in Williams-Beuren syndrome.

This study is presented to identify and characterize the spectrum of the cardiovascular anomalies in children presenting with Williams-Beuren syndrome and cardiovascular anomalies at The Hospital for Sick Children, Toronto from 1966 to 1988. Forty-nine children were diagnosed and followed. The female to male ratio was 1.2:1. The age ranged from 1 month to 14 years at the time of diagnosis (mean 39 months), and follow-up periods were from 9 months to 20 years (mean 10 years). All patients having the typical features were also evaluated by geneticists. Based on cardiovascular findings four groups were identified. Group 1 had isolated supravalvular aortic stenosis (SVAS) (28 patients). There was follow-up in 24 of these children. Six had worsening of supravalvular narrowing and underwent surgery. One showed an increased gradient from 10-40 mmHg during 7 years. Seventeen had mild narrowing and showed no progression over a period of 75 months. Group 2 had isolated pulmonary artery branch stenosis (8 patients). Seven had mild narrowing which remained unchanged over a mean period of 16 months and one underwent surgery. Group 3 had combined lesions (11 patients). Six showed increased left-side narrowing, while right-side obstruction remained static or improved. Five showed improvement in narrowing in both outflow tracts. Five underwent surgery. Additional cardiovascular anomalies included peripheral artery stenosis in two patients, coronary artery abnormalities in three, mitral valve prolapse in three, and coarctation of the aorta in two. Group 4 had isolated lesions. One patient had isolated coarctation of the aorta and one isolated mitral prolapse.(ABSTRACT TRUNCATED AT 250 WORDS)

Left ventricular thrombus following repair of truncus arteriosus.

A 6-month-old infant developed a left ventricular thrombus in association with low antithrombin-III activity following the repair of a truncus arteriosus. Conservative management was associated with spontaneous resolution of the clot. The significance of this association is discussed.

Infantile hypertrophic cardiomyopathy with QT prolongation.

A neonate presented with neonatal myocardial dysfunction and long QT interval with subsequent appearance of hypertrophic cardiomyopathy at one week of age. Maternal glucose metabolism was normal. By 15 months of age the hypertrophy had largely resolved but the long QT persisted. The possible relationship between these conditions is discussed.

Mechanisms of digoxin-amiodarone interaction in the rat.

Amiodarone and digoxin are often used in combination and clinical experience suggests that amiodarone may increase serum digoxin levels and toxicity. We have investigated the influence of amiodarone on digoxin pharmacokinetics and tissue distribution in the rat. Forty-nine rats were injected with 10 mg/kg amiodarone sc three times a day for 7 days, while 49 others were injected with saline only. On the eighth day, all the rats received 0.5 mg/kg digoxin ip; 4, 5, 6, 7, 8, 10, and 12 hr later, groups of 7 amiodarone-pretreated and control animals were sacrificed, and plasma, heart, liver, muscle, brain, and kidney digoxin concentrations measured by radioimmunoassay. Data were analyzed by two-way ANOVA, with group comparisons using the Waller-Duncan multiple comparison procedure. Digoxin levels were significantly higher in the plasma, heart, muscle, and kidney of the amiodarone-pretreated rats at most points of measurement (P less than 0.05) whereas liver digoxin levels were elevated at 8, 10, and 12 hr. Kidney/plasma, heart/plasma, muscle/plasma, and especially liver/plasma ratios in the control groups significantly exceeded the values found in the amiodarone-pretreated group at most time points. Concentrations of digoxin in brain were not changed. This suggests that the volume of distribution is significantly altered in the amiodarone-pretreated group. Amiodarone increases plasma digoxin levels in rats as it does in humans, but the mechanism is unclear.