Pharmacokinetics and pharmacodynamics of sotalol in a pediatric population with supraventricular and ventricular tachyarrhythmia.

OBJECTIVE: This pharmacokinetic-pharmacodynamic study was designed to define the steady-state relationship between pharmacologic response and dose or concentration of sotalol in children with cardiac arrhythmias, with an emphasis on neonates and infants. METHODS: The treatment consisted of an upward titration with unit doses of 10, 30, and 70 mg of sotalol per square meter of body surface area. The patients received 3 doses at each dose level. The dosing interval was 8 hours. The Class III and beta-blocking activities of sotalol were derived from the QT and R-R intervals, respectively, of the surface electrocardiogram, which was recorded at 6 scheduled times before and after the third, sixth, and ninth doses. During these three dose intervals, 4 scheduled blood samples were also collected. Drug concentrations were measured with a validated nonstereoselective liquid chromatographic tandem mass spectrometric detection assay. Pharmacokinetic and pharmacodynamic parameters were obtained with standard methods. RESULTS: Twenty-one centers enrolled 25 patients in the study: 7 were neonates, 9 were infants, and 11 were children between the ages of 2 years and 12 years. The area under the drug concentration-time curve increased proportionately with dose. The apparent oral clearance of sotalol was linearly correlated with body surface area and creatinine clearance. The smallest children (body surface area <0.33 m2) displayed greater drug exposure than the larger children. The increase of QTc and R-R intervals was dose dependent. At the 70-mg/m(2) dose level, the mean (+/- standard deviation) maximum increase for the QTc interval was 14% +/- 7% and the average Class III effect during a dose interval was 7% +/- 5%. At the same dose level, the mean maximum increase of the R-R interval was 25% +/- 15% and the average beta-blocking effect during a dose interval was 12% +/- 13%. The effects tended to be larger in the smallest children. The Class III response and the plasma concentrations of sotalol were linearly related. The treatment was well tolerated. CONCLUSIONS: The steady-state pharmacokinetics of sotalol were dose proportionate. Pharmacologically important beta-blocking effects were observed at the 30-mg/m2 and 70-mg/m2 dose levels. Important Class III effects were seen at the 70-mg/m2 dose level. The Class III effect was linearly related to the drug concentration.

Increasing oral fluids in chronic constipation in children.

Increasing the amount and type of fluid intake in children with simple constipation remains a common intervention recommended by both the medical profession and lay consumers. Efforts to increase overall water intake and/or high osmolarity liquid intake have no research or physiological basis that would result in softer and/or more frequent stools. The purpose of this project was to identify whether an effect on stooling characteristics would be noted with a concerted effort to increase liquid intake.

Are chest radiographs and electrocardiograms still valuable in evaluating new pediatric patients with heart murmurs or chest pain?

OBJECTIVES: To determine the usefulness of electrocardiography (ECG) and chest radiography (CXR) in evaluation of patients referred to the pediatric cardiologist for the evaluation of heart murmur or chest pain. DESIGN: In this prospective study, 106 consecutive outpatients were categorized with no heart disease, possible heart disease, or definite heart disease based on history and physical examination; they then underwent ECG and CXR. Studies were reviewed and the examining cardiologist could change the diagnosis and order an echocardiogram. SETTING: Academic pediatric cardiology practice. RESULTS: In patients thought to have no heart disease, the diagnosis was changed to definite heart disease in four solely on the basis of abnormal CXR or ECG. In 25 patients thought to have possible heart disease, the diagnosis was changed to no heart disease (7) or definite heart disease (5) after review of the CXR and ECG. All 25 patients diagnosed with definite heart disease had this confirmed by abnormal CXR (2), ECG (3), both abnormal CXR and ECG, or echocardiogram (18). CONCLUSIONS: ECG and CXR helped diagnose heart disease in four patients thought to have no heart disease, helped to rule out lesions in seven patients with possible heart disease, helped diagnose heart disease in five patients thought to have possible heart disease, and helped confirm heart disease in nine patients. In these days of cost containment, routine ECG and CXR continue to be valuable tools for the pediatric cardiologist in evaluation of patients with heart murmurs or chest pain.

Role of right ventricular endomyocardial biopsy in infants and children with suspected or possible myocarditis.

OBJECTIVES: To assess the diagnostic yield, sampling errors, risks, and therapeutic implications of right ventricular endomyocardial biopsy in children with suspected or possible myocarditis. DESIGN: Retrospective study. SETTING: Tertiary referral centre for paediatric cardiology, cardiac surgery, heart transplantation, and mechanical circulatory support. PATIENTS AND METHODS: Review of clinical and histological findings among 63 consecutive children with possible myocarditis undergoing right ventricular endomyocardial biopsy. Review of cardiac histology at subsequent necropsy or after explantation at time of transplantation. RESULTS: From January 1980 to December 1992, 76 biopsies were performed in 63 children (2 weeks to 18 years of age). In 41 cases, the biopsy was performed for evaluation of dilated cardiomyopathy. The median interval from onset of symptoms was one month. Eight children (20%; all with a history of less than six weeks duration) had biopsy proved myocarditis. Five of the eight children made a full recovery, including four who presented in cardiogenic shock. By contrast, only three of 33 children without evidence of myocarditis showed recovery of ventricular function. The whole heart was available for histological examination in 23 patients. Myocarditis was confirmed in one patient, and no evidence of myocarditis was found in the remaining 22 (all with negative biopsies). One procedure related death occurred in a 2 week old infant with dilated cardiomyopathy. In 22 cases, biopsy was performed for the evaluation of arrhythmia. Only one biopsy showed myocarditis. CONCLUSIONS: The diagnostic yield of a biopsy is low in children with arrhythmias. In children presenting with profound ventricular dysfunction, a diagnosis of acute myocarditis may avoid premature consideration of transplantation as this group has an important potential for full recovery. In less critically ill patients and in those with a longer duration of symptoms the justification for biopsy is not as clear and the procedure is not without risk.

Transatrial lead placement for endocardial pacing in children.

Transvenous placement of endocardial leads in children may be difficult due to restrictions and complications of vascular access. We have placed endocardial leads from a transatrial approach in 5 children with various cardiac malformations. The usual surgical approach involved an anterolateral thoracotomy and, under fluoroscopic guidance, passage of the lead tip directly through the right atrial wall and across the tricuspid valve to the apex of the right ventricle. At a mean follow-up time of 23.2 months (range, 12.0 to 27.9 months), all patients have low thresholds for myocardial capture, and there have been no complications. We conclude that placement of endocardial leads by a transatrial approach provides an excellent alternative to an epicardial system in children destined for lifelong pacing.

Long-term results of survivors of surgical valvotomy for severe aortic stenosis in early infancy.

Long-term morbidity and mortality were evaluated in the 21 survivors of a cohort of 51 consecutive infants with severe aortic valve stenosis who underwent surgical treatment in the first 3 months of life during the period from 1958 to 1988. The 21 early survivors have been followed up from 3 to 27 years (median 7.5 years). There have been two late deaths: one at age 13 year from bacterial endocarditis and the other at age 14 years after dislodgment of a prosthetic valve. The calculated 10-year actuarial survival for this group is 100%, with a 15-year actuarial survival of 75% (standard error 15%). Seven repeat operations have been performed in six patients: Three had persistent stenosis and a repeat valvotomy was performed in two of them, aged 2 years and 15 years. The other underwent placement of a conduit from the left ventricle to the descending aorta at 2 years of age. Replacement of the aortic valve has been performed in four patients because of severe valvular insufficiency 13 to 27 years after the initial operation. One of these had required a repeat valvotomy at the age of 15 years. The calculated actuarial freedom from reoperation at 10 years is 90% (standard error 6%) and at 15 years, 67% (standard error 15%). Aortic insufficiency was progressive throughout the period of follow-up. No patient had more than moderate aortic insufficiency 3 to 5 years after the initial valvotomy, whereas aortic insufficiency was severe in five of the eight patients followed up for 11 or more years. Progression of aortic insufficiency and the need for reoperation were not related to the age at initial valvotomy. Survivors of surgical aortic valvotomy in early infancy have a relatively good long-term prognosis and a high freedom from reoperation in the period leading to adolescence. Aortic insufficiency in these patients is progressive, and valve replacement eventually may be required.

Coronary arteriosclerosis in pediatric heart transplant survivors: limitation of long-term survival.

Because coronary atherosclerosis after heart transplantation has been a limiting problem in long-term survival of adults, we reviewed the coronary angiograms, and autopsy data when available, from 21 of 30 children who underwent orthotopic heart transplantation and survived the perioperative period. Six patients had coronary atherosclerosis, and five of these patients died 6 months to 3 years after heart transplantation. The late deaths were sudden and unexpected. Coronary angiography demonstrated several types of lesions, including concentric narrowing, tubular segmental lesions, and abrupt obliteration of major coronary vessels. Risk factors assessed included hypertension, hyperlipidemia, cytomegalovirus infection, type of immunosuppressive regimen, number of rejection episodes, and major histocompatibility antigen mismatches. Only the frequency and duration of rejection episodes seemed to be more prevalent in the patients in whom coronary atherosclerosis developed. Despite the benefits of heart transplantation in treating children with end-stage heart disease, coronary atherosclerosis may limit long-term survival. We suggest that these children should undergo serial coronary angiography to identify those at risk for subsequent events related to coronary artery disease.

Extracorporeal membrane oxygenation for postcardiotomy cardiogenic shock in children.

Size limitations and technical barriers prohibit the use of many conventional mechanical circulatory support systems for postcardiotomy ventricular dysfunction in pediatric populations. Extracorporeal membrane oxygenation (ECMO), frequently used to treat neonatal respiratory failure, can provide cardiac support and is effective treatment of postoperative myocardial failure in children. From 1981 to 1987, 10 patients aged 2 days to 5 years were maintained on ECMO for 15 to 144 hours (mean duration, 92 +/- 16 hours) after cardiotomy. Operative procedures included repair of tetralogy of Fallot (2 patients), closure of a ventricular septal defect (2), the Senning procedure for transposition of the great arteries (1 patient), repair of interrupted aortic arch with closure of a ventricular septal defect (1), repair of a partial atrioventricular septal defect (2), closure of a ventricular septal defect with excision of an anomalous muscle bundle (1), and the Fontan procedure (1). Venoarterial ECMO was established in all 10 children. Six patients underwent transthoracic right atrium-ascending aorta cannulation, 3 had right internal jugular vein-right common carotid artery cannulation through a cervical incision, and 1 had right internal jugular vein-left axillary artery cannulation. Eight of the 10 patients were successfully weaned from ECMO, and 7 are long-term survivors. There were 3 deaths; 1 was caused by cardiac and acute renal failure complicated by sepsis two days after decannulation, another occurred 19 days after atrioventricular septal defect repair, and 1 was caused by massive pulmonary hemorrhage. Major hemorrhage developed in 3 patients while on ECMO; 2 required premature decannulation for mediastinal bleeding from operative sites and ultimately survived, and 1 died of respiratory failure as a result of endobronchial bleeding. We conclude that the use of ECMO in pediatric populations for transient postoperative ventricular dysfunction improves survival with limited overall morbidity.

Extracorporeal membrane oxygenation in children. New trends.

At the Children's Hospital of Pittsburgh the extracorporeal membrane oxygenation program was started in 1980. The results of our experience from 1980 to 1985 were previously reported. In the past 2 years 39 additional newborn infants have been treated with this modality, with an overall survival rate of 79% (31/39). This survival rate is much better than that obtained in 33 neonates who had been treated in the previous 5 years (54%; p less than 0.05). A new aspect of our extracorporeal membrane oxygenation program is the use of total apneic lung rest for persisting pulmonary interstitial emphysema during support with the oxygenator. Six neonates were treated with this technique because of worsening pulmonary interstitial emphysema during extracorporeal circulation. Five of them survived. Another indication for extracorporeal membrane oxygenation in our pediatric population has been left ventricular or biventricular failure after cardiopulmonary bypass. Four of our seven patients treated for this indication are long-term survivors. At present, because of the impossibility of using other forms of left ventricular assist devices in the pediatric population, it seems that extracorporeal membrane oxygenation is the most effective treatment for left ventricular failure after cardiopulmonary bypass. From our experience, even in the absence of long-term follow-up of patients supported with extracorporeal membrane oxygenation, it appears that the benefits of this therapeutic modality far exceed the risks in the high-risk population for which it is being used.

Late follow-up of children after heart transplantation.

The majority of late recipients of heart transplantation have returned to age-appropriate activities and are showing normal linear growth. The only child who has significant symptoms is an 11-year-old heart-lung transplant recipient who developed airway rejection with restrictive pulmonary function 14 months after transplantation. Rejection continues to be a major threat to these children more than a year removed from their transplantation procedure. Until a satisfactory noninvasive method is developed to monitor graft rejection, endomyocardial biopsies will continue to be performed at 6-month intervals. Cyclosporine nephrotoxicity and systemic hypertension remain important and unresolved problems that could limit the initial success of transplantation. We believe that heart transplantation is an acceptable option for children with end-stage heart and heart-lung disease who have a grim outlook. Future improvements in immune suppression, and the development of improved methods of assessing rejection, will allow for improved survival.

Long-term follow-up after aortic valvuloplasty and defect closure in ventricular septal defect with aortic regurgitation.

The clinical course was studied in 25 patients with ventricular septal defect (VSD) and aortic regurgitation (AR) who had undergone aortic valvuloplasty and VSD closure. Twelve patients had a doubly committed subarterial VSD and 13 had a perimembranous type of VSD. Preoperatively, progressive hemodynamic disturbance after the onset of AR occurred in 11 patients (44%). The follow-up period extended from 6 months to 23 years (mean 10 years). Four patients required prosthetic valve replacement after valvuloplasty. One of these had had initial improvement of the AR but required valve replacement 20 years later; the condition of the other 3 did not improve initially and their valves were replaced 1 month to 8.5 years later. Four other patients had no initial improvement as a result of valvular reconstructive surgery, but the AR did not progress and remained hemodynamically well tolerated. Hence, the overall success rate of the valvuloplasty, defined as improving or preventing progressive AR, was 21 of 25 (84%). Since initial and long-term improvement in aortic valve function can be expected in most patients after valvuloplasty and closure of the VSD, early surgical intervention is recommended in patients with a VSD and AR.

Experience with heart transplantation in children.

Between March 1981 and March 1986, 200 orthotopic heart transplantations were performed at the University of Pittsburgh. Fourteen of those procedures were carried out in children 2 to 16 years of age. Two children received combined liver and heart transplants; one because of familial hypercholesterolemia with associated ischemic heart disease, and the other because of dilated cardiomyopathy associated with intrahepatic biliary atresia. Eight patients had dilated cardiomyopathy, and two had myocarditis. Two had heart transplantations for congenital heart disease: one had multiple muscular ventricular septal defects repaired in infancy and had an associated cardiomyopathy, and the other developed a cardiomyopathic ventricle from a congenital right coronary artery to right atrial fistula. Chronic immune suppression consisted 0.2 to 0.5 mg/kg/d of prednisone and 5 to 50 mg/kg/d cyclosporine, with the addition of antithymocyte globulin for unresolved moderate or severe acute rejection. There were three early postoperative deaths: one from intracranial bleeding, one from Pseudomonas mediastinitis, and one from ischemic injury to transplanted organs. Early postoperative complications included reversible renal failure, hypertension, and seizures. Late problems were related to allograft rejection and side effects of cyclosporine and corticosteroids. Significant rejection episodes occurred in all patients surviving longer than 2 weeks, with seven requiring antithymocyte globulin. Two patients died 8 months following transplantation of severe acute and chronic rejection; another patient required retransplantation for ischemic cardiomyopathy resulting from chronic rejection but subsequently died of recurring rejection 3 months after the second transplantation.(ABSTRACT TRUNCATED AT 250 WORDS)

Echocardiographic findings before and after liver transplantation.

Echocardiographic studies were performed in 73 patients with various types of chronic liver disease. They were 0.5 to 19 years old (mean 5). Thirteen patients underwent follow-up echocardiography 1 to 13 months (mean 6) after liver transplantation. Preoperatively 60 patients (82%) showed evidence of high cardiac output (cardiac index greater than 4 liters/min/m2); these patients manifested increased left ventricular (LV) and left atrial dimensions and a thickened LV posterior wall. Transvenous contrast echocardiographic study confirmed the presence of intrapulmonary arteriovenous shunting in 4 patients. Studies after liver transplantation revealed a reduced LV end-diastolic dimension in 12 patients. Cardiac index was reduced a mean of 35% after transplantation (p less than 0.001). This study suggests that liver transplantation improves common hemodynamic abnormalities in chronic liver disease.

Ventricular septal defect associated with aneurysm of the membranous septum.

The most common variety of ventricular septal defect, a perimembranous defect, is frequently associated with a so-called aneurysm of the membranous septum. Previous studies have suggested that ventricular septal defects associated with an aneurysm of the membranous septum tend to spontaneously decrease in size or close more than defects without such an aneurysm. To better define the natural history of this entity, clinical and catheterization data from 87 patients with ventricular septal defect and aneurysm of the membranous septum were reviewed. The initial evaluation was made at a median age of 0.3 years (range 0.1 to 11), with the final evaluation at a median age of 10 years (range 1.5 to 20) and a median duration of follow-up of 8.6 years (range 1.2 to 18.8). Approximately 75% of the ventricular septal defects had a small or no left to right shunt at last evaluation. Overall, 48 patients (55%) had no significant change in the size of the defect, and 39 (45%) showed improvement during the period of observation. Only four patients (5%) had spontaneous closure of the defect. Of the 49 patients who presented with a large left to right shunt, with or without congestive heart failure, 23 (47%) had persistence of a shunt large enough to warrant surgery. When spontaneous improvement occurred, it did so by 6 years of age in all but one patient. Therefore, a continued tendency for a ventricular septal defect associated with an aneurysm of the membranous septum to spontaneously decrease in size or close after this age may be less likely than previously suggested.(ABSTRACT TRUNCATED AT 250 WORDS)