Cardiopulmonary interaction during partial liquid ventilation in surfactant-treated preterm lambs

Gas ventilation following instillation of perfluorochemical (PFC) liquid, partial liquid ventilation (PLV), improves gas exchange and pulmonary mechanics in neonatal animals and humans with severe respiratory distress. The effect of PLV on cardiac contractility, performance, pulmonary blood flow and ductal shunt has not been fully described. To this end, we evaluated these indices of cardiopulmonary function in eight conventionally gas ventilated, surfactant-treated premature lambs (125 days gestation) before and during PLV. Animals were instrumented with central venous and aortic lines. Serial evaluation of arterial blood chemistry/pressure, and pulmonary mechanics was performed; cardiac contractility, performance, pulmonary blood flow and ductal shunts were serially assessed by echocardiography. As compared to conventional gas ventilation, during PLV there was a significant decrease in left ventricular meridian (22.5+/-6.6 SE vs 8.1+/-1.4 SE g/cm2, P < 0.02) and circumferential wall stress (54.1+/-16.5 vs 24.4+/-3.8 SE g/cm2, P < 0.04) at end systole. The fall in wall stress at end systole was associated with a significant decrease in left ventricular internal diameter (1.2+/-0.05 SE vs 1.04+/-0.045 SE cm; P < 0.01). There were no significant changes in heart rate, systemic arterial and central venous pressures, systemic vascular resistance, left ventricular shortening and ejection fractions during PLV. The decrease in wall stress was associated with a significant decrease in mean airway pressures (15.9+/-1.1 SE vs 9.9+/-0.2 SE cmH2O; P < 0.05) and ostensibly a change in intrathoracic pressures during PLV. There were no significant differences in blood flows (pre vs during PLV; ml/min/kg): pulmonary (226+/-62 SE vs 293+/-65 SE), aortic (237+/-36 SE vs 204+/-21 SE), and left to right ductal (119+/-25 SE vs 105.5+/-26 SE) measured before and during PLV.

CONCLUSION

Cardiac output and pulmonary blood flow do not change significantly during PLV and therefore do not appear to contribute to improved gas exchange. This stable cardiac performance occurs at lower wall stress and thereby more advantageous energetic conditions.

Sudden death in childhood due to right ventricular dysplasia: report of two cases

Two cases of sudden death due to arrhythmogenic right ventricular dysplasia (ARVD) occurring in the pediatric age group are described. One of the subjects, at the age of 7 years, is believed to be the youngest child in whom ARVD has been diagnosed at autopsy. The clinical and pathological characteristics of ARVD are discussed.

Cerebral rhinocele, hydrocephalus, and cleft lip and palate in infants with cardiac fibroma

Cardiac transplantation was performed in two infants with unresectable fibromas of the myocardium. In one patient, lip surgery was also required for unilateral cleft lip and palate. At autopsy, communicating hydrocephalus of mild to moderate degree was found in both cases. In the patient with facial clefts, there was also a large, ipsilateral cyst, or rhinocele, of the olfactory lobe. This unusual lesion, which seems to represent a previously unreported malformation, was apparently formed by segmental dilatation of a persistent olfactory ventricle. Cerebral or cranial anomalies are thought to be rare in cases of cardiac fibroma; however, macrocephaly was present in five patients. Furthermore, presenting abnormalities among previously reported cases included hydrocephalus in one case, and cleft lip and palate in another. These and other findings suggest that, at least in some cases, cardiac fibroma is a manifestation of a more extensive developmental disorder.

Ectopic automatic atrial tachycardia in children: clinical characteristics, management and follow-up

Ectopic automatic atrial tachycardia, an uncommon type of supraventricular tachycardia in children and adults, has been reported to be resistant to medical therapy, and surgical or cryoblation has been recommended. This report describes 10 infants and children (median age 6 months; range birth to 7.5 years) with automatic atrial tachycardia and their management and follow-up. Digoxin alone was unsuccessful in controlling tachycardia in all 10 patients but decreased the tachycardia rate by 5 to 20% in 8. Intravenous (0.1 mg/kg body weight per dose) and oral propranolol successfully suppressed tachycardia in three of five patients and oral propranolol successfully controlled tachycardia in two of five other patients. Class I antiarrhythmic agents--quinidine (three patients), procainamide (four patients) and phenytoin (three patients)--did not control tachycardia in any patients but made the tachycardia rate worse in three patients. Intravenous (5 mg/kg per dose) and oral amiodarone suppressed tachycardia in three of four patients and oral amiodarone suppressed it in another patient. Thus, intravenous propranolol and amiodarone were effective in acutely suppressing automatic ectopic atrial tachycardia and predicted the response to long-term oral therapy. One patient had persistent tachycardia after surgical ablation of the high right atrial ectopic focus, and another patient had unsuccessful catheter ablation of the high right atrial ectopic focus (25 J). During follow-up (10 to 28 months), ectopic atrial tachycardia resolved completely in four patients and was well controlled in four patients.

Pediatric heart transplantation at St. Christopher's Hospital for Children

Heart transplantation has become the standard of care for patients with end-stage heart failure. The efficacy and therapeutic advantages of transplantation in the pediatric population have not been fully determined. Between March 1985 and September 1986, nine pediatric heart transplantations were performed; the ages ranged from 39 days to 19 years; weight ranged from 2.3 to 100 kg. The underlying disease was acquired cardiomyopathy (four patients); cardiomyopathy caused by congenital mitral valve disease (two patients); unresectable fibroma of the left ventricle in a newborn (one patient); hypoplastic left heart syndrome (one patient); and hypertrophic obstructive cardiomyopathy (one patient). Initial immunosuppression therapy consisted of cyclosporine, prednisone, and antithymocyte globulin. Recently, newer protocols have evolved through experience. Seven patients survived the perioperative period and had follow-up from 1 to 19 months, for a total of 41 transplant months. Rejection occurred at a rate of 1.4 episodes per month in children compared with 0.8 episodes per month in our adult patients. There was no statistical difference in the number, severity, or timing of rejection episodes in the pediatric versus adult population. Major complications included cyclosporine-induced seizures in two patients, mild hypertension in two, five infectious episodes (three bacterial and two viral), and three late deaths. All children who survived are in New York Heart Association functional class I with no developmental delays. This series is heavily weighted with children (33% less than age 1 year). Early results demonstrate that pediatric and infant heart transplantation is technically practical. Improved results are to be expected with additional experience and further modification of adult protocols to assure patient growth and minimize the high infection rate.

Endomyocardial biopsy after heart transplantation in children

Clinical evaluation, physical examination, and noninvasive testing have been suggested as adjuncts to endomyocardial biopsy for diagnosing acute graft rejection in children after heart transplantation. Because the consequences of delayed diagnosis or unnecessary treatment of rejection may be serious in pediatric transplant recipients, we reviewed our experience with repeated endomyocardial biopsy in seven children (aged 6 months to 19 years) and assessed the sensitivity and specificity of clinical and noninvasive data for diagnosing acute rejection. There were no serious complications in 71 biopsy procedures. In no patient did the presence of abnormal clinical findings or noninvasive testing coincide with treatable rejection that was proved on biopsy. However, there were nine episodes of treatable rejection in the absence of abnormal physical findings or noninvasive studies. At this time we consider repeated endomyocardial biopsy to be a feasible and safe procedure in infants and children and do not consider clinical findings and noninvasive testing sufficient to make therapeutic judgments in regard to acute graft rejection.

Postoperative evaluation of complex congenital heart disease by magnetic resonance imaging

This study suggests that the use of MRI together with echocardiography may reduce the need for serial cardiac catheterizations in the postoperative care of children with complex congenital heart disease.

Magnetic resonance imaging of rerouted pulmonary blood flow

Correction of structural defects of the heart associated with cyanotic heart disease often requires rerouting of systemic venous return into the pulmonary arteries and pulmonary venous return into the ventricles. Preliminary experience suggests that magnetic resonance imaging, through its superior depiction of the resultant complex anatomy, provides important supplemental information to echocardiography. Together, these noninvasive techniques may lessen the present need for repeat catheterization in children with surgically corrected cyanotic heart disease.

Advances in noninvasive evaluation of congenital anomalies of the thoracic aorta

Two-dimensional echocardiography, Doppler ultrasound, and magnetic resonance imaging (MRI) have greatly enhanced the noninvasive diagnosis of congenital anomalies of the thoracic aorta. Both sonic and magnetic resonance techniques can obviate preoperative invasive studies, and both provide an excellent means of follow-up. Ultrasound will likely remain the most valuable modality in neonates, while MRI promises to make an important contribution in older children and adults.

Assessment of systolic ventricular muscle function in man: the end systolic index

Accurate assessment of ventricular muscle contractile function in patients with heart disease is impaired by alterations in afterload, preload and wall thickness which often accompany the disease. The relationship between pressure and volume at end systole is considered to provide a contractile index which is independent of preload and which accounts for afterload. Use of the index prerequisites determinations of the left ventricular end systolic pressure, wall thickness as well as the dimensions or volumes, respectively, which may be assessed with either invasive or noninvasive methods. In patients with aortic stenosis and congestive heart failure, there was a significantly reduced slope (0.9 +/- 0.5) of the end systolic stress-volume relationship as compared with healthy subjects (5.8 +/- 1.3) or patients with aortic stenosis without congestive heart failure (3.9 +/- 1.3), while the ejection fraction showed no significant differences. In patients with mitral regurgitation with no or only minimal symptoms postoperatively, preoperatively the end systolic index (ESS/ESVI) was higher (3.3 +/- 0.4) than in patients with marked symptoms postoperatively or those who died perioperatively (2.2 +/- 0.2) and the values of both patient groups were lower than those of normals. In contrast, the values for ejection fraction among the normals and both groups of patients showed substantial overlap. In patients with aortic insufficiency and congestive heart failure, as opposed to patients with aortic insufficiency and only slight symptoms, there was a significantly compromised ejection fraction as well as diminished end systolic index (ESS/ESVI). Patients with hypertension accompanied by congestive heart failure had a significantly diminished slope of the relationship between end systolic left ventricular stress and volume while the values for hypertensive patients without congestive heart failure were within normal limits; in both groups of patients, the ejection fraction was normal. In patients with mitral stenosis, the end systolic index at 5.28 +/- 0.53 did not differ significantly from that of healthy subjects at 4.87 +/- 0.53, while the velocity of circumferential fiber shortening was diminished. Patients with large atrial septal defects and symptoms of congestive heart failure did not differ with respect to end systolic index or ejection fraction as compared with atrial septum defect patients without symptoms. In children with aortic stenosis and high pressure gradients, there was an increased ejection fraction together with a normal end systolic index.(ABSTRACT TRUNCATED AT 400 WORDS)

Dilatation of the descending aorta: a radiologic and echocardiographic diagnostic sign in arteriovenous malformations in neonates and young infants

Eleven infants with arteriovenous malformations were admitted to St. Christopher's Hospital for Children between 1970 and 1978. Dilatation of the descending aorta was seen in the chest roentgenogram in 8 of the 11 patients. Echocardiography used in the two most recent cases revealed approximation of the descending aorta to the posterior left atrial and left ventricular wall in association with generalized cardiomegaly. The most frequently reported radiologic findings in infants with arteriovenous malformations are cardiomegaly, increased pulmonary vasculature and a widened superior mediastinum. These findings can accompany other congenital malformations of the heart, but the radiographic and echocardiographic findings of a dilated descending aorta appear to be more specifically associated with arteriovenous malformations in the neonate and infant.