Cardiac arrhythmias in the human fetus.

Fetal cardiac arrhythmias have been recognized with increasing frequency during the past several years. Most fetal arrythmias are intermittent extrasystoles, often presenting as irregular pauses of rhythm. These are significant only when they occur with appropriate timing to initiate sustained tachycardia, mediated by anatomic bypass pathways. The most common important fetal arrhythmias are: 1) supraventricular tachycardias, and 2) severe bradyarrhythmias, associated with complete heart block. Symptomatic fetal tachycardias are usually supraventricular in origin, and may be associated with the developmet of hydrops fetalis. These patients may respond to antiarrhythmic drug therapy, administered via maternal ingestion or via direct fetal injection. Such therapy should be offered with careful fetal and maternal monitoring, and must be based on a logical, sequential analysis of the electrical mechanism underlying the arrhythmia, and an appreciation of the pharmacology and pharmacokinetics of the maternal, placental fetal system. Bradycardia from complete heart block may either be associated with complex congential heart malformations involving the atrioventricular junction of the heart, or may present in fetuses with normal cardiac structure, in mothers with autoimmune conditions associated with high titres of anti-SS-A or anti-SS-B antibody, which cross the placenta to cause immune-related inflammatory damage to the fetal atroventricular node. This paper reviews experience with the analysis of fetal caridac rhythm, a detailed discussion of the pathophysiology of arrhythmias and their effect on the fetal circulatory system, and offers a logical framework for the construction of treatment algorithms for fetuses at risk for circulatory compromise from fetal arrhythmias.

Ectopic cardiac calcification associated with hyperparathyroidism in a boy with hypophosphatemic rickets.

An adolescent with hypophosphatemic rickets developed cardiac calcifications in the absence of hypercalcemia or elevation of the phosphocalcic product (the product of the total serum calcium and phosphorus concentrations). Cardiac calcifications led to aortic and mitral valve dysfunction, myocardial calcification, and arrhythmia. Hyperparathyroidism probably played a significant role in the development of this complication, which emphasizes the necessity for intermittent assessment of parathyroid status in individuals receiving medical therapy for hypophosphatemic rickets.

Preterm infants with paroxysmal supraventricular tachycardia: presentation, response to therapy, and outcome.

OBJECTIVES: We investigated the clinical course of preterm infants with paroxysmal supraventricular tachycardia in comparison to their term counterparts. BACKGROUND: Paroxysmal supraventricular tachycardia (PSVT) is the most common arrhythmia in childhood. It is known to cause significant morbidity and rarely mortality, most commonly in infants. Yet, there is minimal information in the literature on preterm infants with PSVT. METHODS: Retrospective review of 40 infants, 26 term and 14 preterm, less than three months of age who presented with PSVT from January 1990 to January 1999. We compared the severity of first clinical presentation, in-hospital response to long-term medications, and outcome after discharge. RESULTS: Symptomatic severity on presentation was not different between preterm and term infants. Preterm infants required fewer medication trials (p=0.01) and had no recurrences after discharge in contrast with 43 % recurrence in the term infants (p<0.0001). No preterm infants had Wolff-Parkinson-White syndrome (WPW) in contrast to 42 % of term infants (p=0.003). Term infants with WPW were more symptomatic (p=0.01), required more medications (p=0.004), but had a similar recurrence frequency as terms infants without WPW (p=0.95). Excluding infants with WPW, preterm infants were more severely symptomatic (p=0.02), yet no longer was there a difference in response to first medication trial (p=0.30). CONCLUSIONS: We found that preterm infants with PSVT are as severely symptomatic on presentation, require fewer medications for adequate in-hospital control, and have fewer recurrences than their term counterparts. Unexpectedly, preterm infants did not present with WPW. The presence of WPW only in the term infants may account for differences in the clinical course between preterm and term infants.

Evaluation and treatment of other arrhythmic causes of syncope in children and adolescents with an apparently normal heart: Wolff-Parkinson-White syndrome and right ventricular cardiomyopathy.

Syncope could be a symptom of tachyarrhythmias related to the Wolff-Parkinson-White syndrome, or the consequence of the ventricular tachycardias seen in patients with Arrhythmogenic Right Ventricular Cardiomyopathy. Syncope should be considered the consequence of atrial fibrillation or flutter, with rapid conduction over the accessory atrioventricular connection in Wolff-Parkinson-White syndrome, and these patients are at risk of presenting with ventricular fibrillation and sudden death. Radiofrequency ablation of the anomalous, accessory connection, which can be performed with high success and low complication rates, should be the first line of treatment for symptomatic children and adolescents with Wolff-Parkinson-White. Arrhythmogenic Right Ventricular Cardiomyopathy is a rare disorder of the cardiac muscle affecting predominantly, although not exclusively, the right ventricle. Clinical presentation varies from asymptomatic cases to patients with severe symptoms related to life-threatening arrhythmias, right ventricular failure, or congestive heart failure with involvement of both ventricles. The clinical diagnosis is difficult. A set of major and minor criteria has been proposed to help to identify patients with this disease. Without an identified cause, the treatment of patients with Arrhythmogenic Right Ventricular Cardiomyopathy is symptomatic. Medical management of the associated congestive heart failure, pharmacologic treatment of the arrhythmias, radiofrequency ablation and implantable cardioverter-defibrillator therapy should all be considered.

Congenital heart block: development of late-onset cardiomyopathy, a previously underappreciated sequela.

OBJECTIVE: We report 16 infants with complete congenital heart block (CHB) who developed late-onset dilated cardiomyopathy despite early institution of cardiac pacing. BACKGROUND: Isolated CHB has an excellent prognosis following pacemaker implantation. Most early deaths result from delayed initiation of pacing therapy or hemodynamic abnormalities associated with congenital heart defects. METHODS: A multi-institutional study was performed to identify common clinical features and possible risk factors associated with late-onset dilated cardiomyopathy in patients born with congenital CHB. RESULTS: Congenital heart block was diagnosed in utero in 12 patients and at birth in four patients. Ten of 16 patients had serologic findings consistent with neonatal lupus syndrome (NLS). A pericardial effusion was evident on fetal ultrasound in six patients. In utero determination of left ventricular (LV) function was normal in all. Following birth, one infant exhibited a rash consistent with NLS and two had elevated hepatic transaminases and transient thrombocytopenia. In the early postnatal period, LV function was normal in 15 patients (shortening fraction [SF] = 34 +/- 7%) and was decreased in one (SF = 20%). A cardiac pacemaker was implanted during the first two weeks of life in 15 patients and at seven months in one patient. Left ventricular function significantly decreased during follow-up (14 days to 9.3 years, SF = 9% +/- 5%). Twelve of 16 patients developed congestive heart failure before age 24 months. Myocardial biopsy revealed hypertrophy in 11 patients, interstitial fibrosis in 11 patients, and myocyte degeneration in two patients. Clinical status during follow-up was guarded: four patients died from congestive heart failure; seven required cardiac transplantation; one was awaiting cardiac transplantation; and four exhibited recovery of SF (31 +/- 2%). CONCLUSIONS: Despite early institution of cardiac pacing, some infants with CHB develop LV cardiomyopathy. Patients with CHB require close follow-up not only of their cardiac rate and rhythm, but also ventricular function.

Recent developments in the etiology, evaluation, and management of the child with palpitations.

The field of arrhythmias in children has recently seen major advances in several aspects, including diagnosis (event monitoring systems) and treatment (very effective acute and long-term medications) and, more importantly, in the definitive cure of supraventricular tachycardia with the use of catheter ablation techniques. These procedures are very successful and can be performed with a low complication rate. The indications for radiofrequency ablation are expanding and the technical aspects improving rapidly, so a larger number of patients will benefit from this curative treatment.

Amiodarone induced pulmonary fibrosis in infancy.

We report a case of pulmonary fibrosis in an infant receiving amiodarone for treatment of intractable atrioventricular reentrant tachycardia secondary to Wolff-Parkinson-White syndrome. At 9 months, a screening chest radiograph showed a diffuse interstitial infiltrate in an asymptomatic, thriving infant. Amiodarone was discontinued and the pulmonary fibrosis resolved gradually over 6 months. This case documents the first report of amiodarone induced pulmonary fibrosis in the pediatric age group. We speculate that as amiodarone is used more frequently to manage pediatric arrhythmias, pulmonary fibrosis, a known complication of this antiarrhythmia in adults may be seen with increasing frequency in children.

Single coronary artery complicating stent implantation for homograft stenosis in tetralogy of Fallot.

Successful stent implantation for conduit stenosis has been described; however, this procedure may be complicated by compression of adjacent structures during expansion. We report on a rare case of a single right coronary artery system complicating stent implantation for relief of homograft stenosis in tetralogy of Fallot.

Cardiovascular abnormalities in patients with X-linked hypophosphatemia.

Treatment for X-linked hypophosphatemia (XLH; vitamin D metabolites and phosphate salts) may result in hypercalcemia, hypercalciuria, nephrocalcinosis, and hyperparathyroidism. Cardiovascular abnormalities occur in association with these complications, but have not been reported in XLH. We hypothesized that such abnormalities may occur in XLH and evaluated cardiovascular status in 13 patients with this disease. All patients were asymptomatic and had normal cardiovascular physical examinations and Holter studies. Serum calcium and creatinine clearance were normal in all. However, all patients had mild to moderate nephrocalcinosis. Left ventricular hypertrophy was diagnosed by electrocardiogram in three and by ultrasonography in seven children. Baseline blood pressure (BP) was normal (mean +/- SD, 116 +/- 15/74 +/- 6 mm Hg). During exercise stress testing, systolic BP increased in all patients, but the maximal systolic pressure was less than that in healthy age- and sex-matched controls (156 +/- 20 vs. 175 +/- 23; P = 0.002, by t test). An abnormal increase in diastolic BP occurred at all levels of work load in XLH patients; their peak exercise diastolic BP was 91 +/- 12 vs. 72 +/- 6 mm Hg in controls (P < 0.0001, by t test). Whether these abnormal findings are primary defects in XLH or represent complications of treatment is unclear. Patients with XLH should be monitored closely for the development of hypertension and left ventricular hypertrophy. Investigation of the mechanisms involved and establishment of therapeutic guidelines are indicated.

The role of surgical ligation of patent ductus arteriosus in the era of the Rashkind device.

BACKGROUND: The role of surgery in managing patent ductus arteriosus (PDA) was studied in the era of the Rashkind double-umbrella device. METHODS: All 354 patients with PDA referred to our center in a 5-year period were included in this report. Of the 354 patients, 236 underwent cardiac catheterization with the intent of transcatheter PDA closure, and 118 had surgical intervention. RESULTS: In 46 (19.5%) of the 236 patients having cardiac catheterization, the procedure either was abandoned or failed. Color Doppler echocardiography demonstrated total occlusion of the ductus after 24 hours in 97 patients (41%) in the cardiac catheterization group. An additional 20 patients had no residual leaks at follow-up. Twenty other patients underwent reocclusion because of a residual shunt. Thus, of the 236 patients, 137 (58%) had successful complete closure of the PDA. Surgical PDA ligation was performed in 118 patients as the initial procedure and in 26 of the 46 patients in whom transcatheter closure was abandoned. If the remaining 20 patients in whom transcatheter closure failed are added to the 144 patients who underwent PDA ligation, the percentage having surgical intervention versus transcatheter occlusion is higher than 46%. CONCLUSIONS: Our data suggest that surgery plays a major role in the management of patients with PDA despite the advent of new interventional catheterization techniques.

[Multiple pathway tachycardias: electrophysiological properties and fulguration of accessory pathways in 2 cases]. / Taquicardias con circuitos multiples: propiedades electrofisiológicas y fulguración de todas las vías accesorias en dos casos.

We report two patients (male, 35 and female, 28 years old) with recurrent and refractory tachycardias referred for an electrophysiological study. EKG showed left lateral accessory pathway in both, two tachycardias with identical morphology but with different frequency and activation sequence were detected. One was orthodromic with anterograde conduction by the His-Purkinje budle and retrograde by the accessory pathway and the other with slow nodal anterograde conduction. The accessory pathway was first fulgurated with radiofrequency at the third attempt. Posteriorly, a nodal reentry tachycardia was induced in the first patient and in the second, a double nodal pathway was confirmed. In both, the slow pathway was modified using Jackman's technique, after three and four attempts respectively. After these applications, the induction of tachycardia with programmed atrial or ventricular stimulation, with or without isoproterenol, was not possible. It is concluded that radiofrequency fulguration is a reasonable therapeutic alternative for patients with multiple circuit tachycardias.

Anomalous left coronary artery from the main pulmonary trunk: physiologic and clinical importance of its association with persistent ductus arteriosus.

Anomalous left coronary artery (ALCA) from the pulmonary trunk presents in early infancy with a clinical picture of failure to thrive, congestive heart failure (CHF), angina-like episodes, and mitral insufficiency. These manifestations which are due to myocardial ischemia may change in the presence of an associated lesion. We present a case and review two previous reports of a patent ductus arteriosus (PDA) associated with this anomaly. Although signs and symptoms are not as clear due to the less impaired coronary perfusion and the presence of a PDA, the presence of mitral insufficiency should raise the possibility of an anomalous coronary artery and, therefore, a cardiac catheterization and angiocardiography are recommended in anticipation of reparative surgery.