Postnatal development of obstruction in coarctation of the aorta: role of the ductus arteriosus.

The sequence of events leading to the development of acute obstruction in two infants with coarctation has been defined by clinical, hemodynamic, and angiographic studies. One infant had normally related great arteries and an isolated coarctation, while the other infant had transposition with a hypoplastic right ventricle, a ventricular septal deffect, narrowing of the aortic isthmus, and a localized site of coarctation. In each instance, a posterior aortic shelf--the basic pathologic lesion in coarctation--could be observed angiographically. Signs of aortic obstruction were absent, however, as long as the ductus arteriosus was widely patent. Following ductal obliteration, femoral pulsations diminished, a peak systolic pressure difference was recorded between the ascending and descending aorta, and a discrete area of juxtaductal coarctation was seen. The basic malformation (posterior aortic curtain) would appear to exist in utero, possibly as an aortic branch point. This lesion is nonobstructive as long as blood can traverse the aortic isthmus through the aortic end of the ductus into the descending aorta. Postnatally, as the ductus arteriosus undergoes constriction at its aortic insertion, signs of acute aortic obstruction may b =ecome apparent. Normal femoral arterial pulsations during the newborn examination do not definitively exclude coarctation. Pediatricians should recheck at 2 weeks of age if the infant is asymptomatic or sooner if there are signs of cardiac failure to establish the presence or absence of this defect.

Effects of acutely increasing systemic vascular resistance on oxygen tension in tetralogy of Fallot.

Effects of phenylephrine hydrochloride on the degree of hypoxia were studied in six cyanotic patients with tetralogy of Fallot. Baseline aortic and right atrial oxygen saturations, blood gas tensions, pH, and indicator-dilution curves were obtained under stable conditions. Phenylephrine was infused while systemic arterial pressure was monitored continuously. Aortic and right atrial blood samples were measured at each 10 mm Hg systolic pressure increment and decrement and analyzed for pH, PO2, PCO2, and oxygen saturation. A 40 mm Hg peak systolic aortic pressure rise was the arbitrary end point for phenylephrine infusion and the indicator-dilution curve repeated. Aortic oxygen tensions rose in all from 4 to 28 mm Hg (mean, 14 mm Hg). The net right-to-left shunt decreased from 10% to 40% (mean, 25%) with phenylephrine infusion as compared to the shunt under basal conditions. The presumed mechanism related to the increase in systemic vascular resistance relative to right ventricular outflow obstruction with resultant augmentation of pulmonary blood flow. It is concluded that acutely raising systemic vascular resistance in patients with tetralogy of Fallot using phenylephrine infusion has a beneficial effect on systemic arterial oxygen level and might be the medical treatment of choice for protracted hypoxic spells.

Effect of physical training on exercise performance of children following surgical repair of congenital heart disease.

The effect of physical training on the exercise performance of 26 patients following surgical repair of tetralogy of Fallot (16 patients) and ventricular septal defect (ten patients) was evaluated. Base line exercise testing was performed on a bicycle ergometer using the technique of Godfrey. Patients were placed on a six-week alternate day submaximal interval home exercise program of varying duration and intensity. Work loads at 50%, 60%, and 70% maximum oxygen consumption were selected to maintain heart rates between 130 and 160 beats per minute. Subjects completed an average of 18 of the possible 21 training sessions (range 11 to 21). A 25% improvement (p less than .001) was noted in maximum work capacity (747 to 935 km). Sixty-five percent of the patients performed at less than expected maximum work capacity prior to training, but only 31% performed at less than expected maximum work capacity after training. Repeat testing at work loads of one-third, one-half, and two-thirds the original maximum work capacity revealed improved aerobic efficiency as manifested by significantly decreased oxygen consumption and heart rate at each level of work. No significant difference was noted in maximum oxygen consumption. It is concluded that physical training can improve the exercise performance of patients after surgical repair, permitting the individuals to function at levels of activity at, or closely approaching, normal.

Echocardiographic studies of the human fetus: prenatal diagnosis of congenital heart disease and cardiac dysrhythmias.

During obstetrical ultrasound examinations, 200 M-mode and 35 real-time two-dimensional echocardiographic studies were performed on 180 fetuses of high-risk pregnancies. Fetal gestational ages ranged from 18 to 41 weeks. M-mode "sweeps" demonstrating mitral- and septal-aortic fibrous continuity were obtained in 115 studies. Paradoxic septal motion in 50 fetuses suggested relarive right ventricular volume loading. Congenital cardiac malformations were accurately diagnosed in a 34-week fetus with pulmonary atresia and hypoplastic right ventricle and in a 28-week fetus with a univentricular heart. Congenital complete atrioventricular block was diagnosed in a 28-week fetus and atrial flutter with variable atrioventricular block was diagnosed in a 38-week fetus. The use of echocardiographic studies to evaluate cardiac structure and rhythm in utero assists in counseling prospective parents and in planning postnatal management for their offspring.

Evaluation of the preterm infant for patent ductus arteriosus.

As a first step in a multicenter, collaborative project to study the role of indomethacin in the management of patent ductus arteriosus in premature infants, a diagnostic scheme was developed, on an a priori basis, by a consensus of the participating neonatologists and pediatric cardiologists. The scheme, which utilizes clinical and noninvasive findings, was designed to detect infants with a "hemodynamically significant" patent ductus arteriosus (PDA). Among 1,689 infants with birth weight less than 1,750 g who were monitored during the first year of the study, 342 (20.2%) met the criteria for PDA. Rates were higher for smaller infants (42% with birth weight less than 1,000 g) than for larger infants (7% with birth weight 1,500 to 1,750 g). Although study protocol did not require a direct procedure to confirm the diagnosis of PDA, a marked decrease in the presence of most criteria was noted following surgical ligation of the ductus. Although the echocardiographic criterion (ratio of left atrium to aorta [LA/Ao] greater than or equal to 1.15) proved to have a low specificity for PDA, the data suggest that the overall scheme led to a very low rate of false-positive diagnosis. Following the application of the scheme for 1 year at 13 clinical centers, it has been shown to be a highly acceptable means of detecting infants with PDA.

Echocardiographic assessment of the severity of aortic stenosis in children and adolescents.

The magnitude of ventricular hypertrophy in response to afterloading is determined by wall stress, with wall thickness increasing in proportion to ventricular load until systolic wall stress is normalized. With use of echocardiographic measurements of left ventricular end-systolic wall thickness (Ws) and cavity transverse dimension (Ds), the pressure constant k was calculated in 16 patients without left heart obstruction according to the formula k = P-Ds/Ws. The mean value for k was 225 +/- 6.7 (standard deviation) mm Hg. From this value, left ventricular pressure was estimated in 13 patients with aortic stenosis aged 4 to 17 years using the formula P = k-Ws/Ds. No subject had evidence of cardiac failure. Peak systolic aortic pressure difference (delta P) was calculated by subtracting cuff-measured brachial arterial peak systolic pressure from the estimated left ventricular pressure. Excellent correlation was obtained between the estimated delta P and that found at cardiac catheterization (r = 0.89). In two patients, echocardiographic data predicted significant obstruction in the presence of normal electrocardiographic, vectorcardiographic and vector lead tracings. Echocardiography offers a noninvasive method for estimating the severity of aortic stenosis, in the absence of myocardial failure; it appears to be more sensitive than other currently employed techniques.

Fetal echocardiography. A tool for evaluation of in utero cardiac arrhythmias and monitoring of in utero therapy: analysis of 71 patients.

Fetal echocardiographic studies were performed in 71 patients referred for evaluation of cardiac rhythm disturbances at 24 to 40 weeks' gestation. After 2-dimensional echocardiographic study of cardiac structure was performed, M-mode echocardiograms were analyzed for measurement of cardiac rate, atrioventricular contraction sequence, atrioventricular valve motion, and duration of postectopic pauses. Arrhythmias were diagnosed in 59 patients. In 34 patients with isolated ectopic beats, the arrhythmia resolved during later pregnancy in 26 or within the first 5 days of life in 8. Six patients had mild sinus bradycardia and 8 had frequent sinus pauses; all 14 had resolution of the arrhythmia during pregnancy. Sustained arrhythmias occurred in 11 patients. Deaths occurred when there was associated fetal congestive heart failure (hydrops fetalis), structural heart disease, or both. M-mode echocardiography diagnosed supraventricular tachycardia in 3 fetuses. The echocardiogram was used thereafter for monitoring transplacental digoxin therapy.

Hypoplastic left heart in a patient with 45,X/46,XX/47,XXX mosaicism.

Recurrence risks for primary congenital heart lesions are well defined. An infant with hypoplastic left heart syndrome is observed to have a short neck with a full skin fold on the right side, unilateral single palmar crease, and whorls on all ten fingers. She was found to have the Ullrich-Turner syndrome with mosaicism 45,X/46,XX/47,XXX. We believe the cardiac malformation was secondary to her aneuploidy. This could have important implications for prediction of recurrence risks to the parents. Chromosomal tests may be indicated for infants were severe congenital cardiac lesions, based on subtle clinical findings.

Left atrial--left ventricular conduit for relief of congenital mitral stenosis in infancy.

Severe congenital mitral stenosis in the infant poses a difficult problem. We present the case history of an infant in whom a left atrial--left ventricular apical conduit was used to bypass a severely hypoplastic mitral valve. Associated coarctation of the aorta, patent ductus arteriosus, and ventricular septal defect were corrected at the same time. This method of circumventing the mitral valve offers a new approach to the relief of congenital mitral hypoplasia in small infants.

d-Transposition of the great arteries and atresia of the mitral and pulmonary valves: association with a normal anatomic left ventricle.

The clinical, angiographic, and pathologic features are presented for a case of d-transposition of the great arteries with atresia of the mitral and pulmonary valves and two well-developed ventricles. The morphologic left ventricle appeared to be functioning as a systemic ventricular aneurysm, and this may have led to the patient's death. A possible explanation for this anomaly is given.

Thirty-year follow-up of superior vena cava-pulmonary artery (Glenn) shunts.

The first superior vena cava-pulmonary artery shunt (Glenn shunt) in our series was performed in February 1958. From then through September 1988, 91 patients have undergone this procedure for a wide variety of congenital defects. We here report follow-up data available on all patients. Ages ranged from 2 days to 46 years (mean 6.8). Diagnoses were as follows: tricuspid atresia, 27; single ventricle, 22; tetralogy of Fallot, 14; D-transposition of the great arteries, ventricular septal defect, and pulmonary stenosis, 9; D-transposition, 5; Ebstein's anomaly, 4; pulmonary atresia + intact septum, 4; and others, 6. The hospital mortality rate was 7.7% (one death in the last 53 patients, 1.9%). Five deaths occurred in patients less than 6 months old. There were 20 late deaths (22%) with actuarial survival rates of 84% and 66% at 10 and 20 years, respectively. Pulmonary arteriovenous fistula formation was seen in 18 patients (19.7%), six of whom have undergone therapeutic embolization with improvement in saturation. The prevalence of pulmonary arteriovenous fistula increases with time after shunt. No long-term shunt thrombosis or stricture formation was seen. Fifty percent of shunts were still functioning at 20 years. Palliation was limited because of decrease in blood flow to the contralateral pulmonary artery, collaterals between the inferior and superior venae cavae, and pulmonary arteriovenous fistula formation. Improvement in saturation was obtained in eight otherwise inoperable patients by creation of a right axillary arteriovenous fistula up to 19 years after the Glenn shunt. Three patients had conversion of a Blalock-Taussig shunt to a Glenn shunt with improvement in congestive heart failure. Twenty-six patients have undergone a Fontan procedure with two deaths. Compared with the group having a Fontan procedure without a prior Glenn operation, there was no difference in early or late mortality. Thirty years after a Glenn shunt, the first patient in this series is working full time after having undergone a modified Fontan procedure in 1981. We conclude that the Glenn connection, usually with supplemental procedures to enhance oxygenation, has provided excellent physiologic palliation with low mortality up to 30 years with no late thrombosis or stricture formation. The incidence of pulmonary arteriovenous fistula increases with time and can be effectively treated with embolization. Physiologic repair after the Glenn shunt carries a low mortality. Although currently used infrequently, superior vena cava-pulmonary artery shunting remains a useful method of palliation in selected patients.(ABSTRACT TRUNCATED AT 400 WORDS)

Prosthetic valve replacement in children.

Reported clinical experience with prosthetic valve replacement in children have suggested a high operative mortality. We placed 25 valves in 24 children with one operative death. There has been one late death related to pacemaker malfunction, but the remainder of the patients have generally done extremely well. The children have not undergone elective anticoagulation, and the long-term embolism rate has not exceeded the incidence of systemic embolization in adults who have been controlled on warfarin sodium (Coumadin) therapy. The objective of prosthetic valve replacement is myocardial preservation. We believe that valve replacement with currently available prostheses should be undertaken in any child with valvular malfunction who is not well controlled with good medical management.

Accessory mitral valve tissue causing left ventricular outflow obstruction (two-dimensional echocardiographic diagnosis and surgical approach).

Accessory mitral valve tissue, a rare cause of left ventricular outflow tract obstruction, can be difficult to diagnose preoperatively and confusing even at surgery. The reported case illustrates how preoperative evaluation can be made using two-dimensional echocardiography combined with Doppler flow analysis. The intraoperative technique for removing the accessory tissue without causing damage to the native mitral valve is discussed.

Cervical aortic arch with retroesophageal aortic obstruction: report of a case with successful surgical intervention.

The clinical, roentgenographic, hemodynamic, and angiographic features of a patient with a right cervical aortic arch and retroesophageal aortic obstruction associated with a ventricular septal defect are presented. Surgical relief of the aortic obstruction was successfully achieved by placement of a bypass graft between the left common carotid artery and the descending thoracic aorta.

Early extubation following pediatric cardiothoracic operation: a viable alternative.

A protocol is presented that facilitates early extubation following pediatric cardiothoracic operations. A total of 197 consecutive patients were managed according to this protocol. Fifty percent of the patients were less than 3 years old. Cardiopulmonary bypass was required in 113 (57%) of the surgical procedures. Extubation immediately following the surgical procedure was accomplished in 142 (72%) of the patients. Pulmonary complications occurred in 8 of these 142 patients (6%) and in 10 (18%) of the 55 patients requiring postoperative mechanical ventilation. Of the patients having early extubation, 5 (4%) required reintubation. One death in this group was unrelated to pulmonary function. There were 16 deaths among the 55 patients managed with mechanical ventilation. Carefully conducted early extubation provided specific advantages over routine postoperative mechanical ventilation. Modern techniques of anesthesia and surgical repair of congenital heart disease can decrease the requirement for postoperative mechanical ventilation and the potential for related complications.

Persistent left superior vena cava causing subdivided left atrium: diagnosis, embryological implications, and surgical management.

A 3-month-old infant is described in whom a persistent left superior vena cava impinged on the posterior wall of the left atrium, producing a subdivided left atrium with left-to-right shunting and congestive heart failure. To our knowledge, this anomaly has not previously been reported. The preoperative diagnosis, surgical management, and embryological implications are discussed.

Effects of alterations of oxygen transport on the neonate.

In the foregoing discussion we have attempted to provide an overview of much of the information available on the effects of changes in systemic oxygen transport on the neonatal and young subject. Using data synthesized from both human and animal studies, we have described the normal developmental changes and the findings of studies in which oxygen transport has been acutely altered by experimental means. This was intended to highlight the potentially delicate balance that can occur between oxygen supply and utilization during the critical period of rapid growth after birth. Finally, using the left-to-right shunt as an example, we have tried to show how a common pathologic condition can impair oxygen transport at multiple sites, and how normal development can make matters worse. It is anticipated that from an understanding of both normal and abnormal physiology, we will be able to develop rational approaches to the management of infants in whom the oxygen transport system has been stressed beyond its reserve.

Apical-aortic shunts in children.

Experience with four children undergoing apicalaortic shunts for relief of aortic valvular disease is reported. All children tolerated the procedure uneventfully, and postoperative cardiac catheterization in three revealed restoration of normal hemodynamics. In one unique case severe aortic regurgitation in a two year old boy was managed by suture closure of the aortic valve producing total left ventricular output through the apical-aortic conduit.

Markedly improved pulmonary function after open heart surgery in infancy utilizing surface cooling, profound hypothermia, and circulatory arrest.

The use of surface-induced profound hypothermia with limited cardiopulmonary bypass and circulatory arrest markedly diminished the need for mechanical ventilation for patients undergoing cardiac surgery. Eleven of twenty-two patients were extubated in the operating room and five more patients within 70 minutes postoperatively. Five patients required mechanical ventilation. Four of the five were extubated within 24 hours (mean, 19.05 hours); only one patient required mechanical ventilation greater than 24 hours. This experience would indicate that as the age of surgery is decreased, in conjunction with improved technics of cardiac surgery and anesthesia, the need for mechanical ventilation should be diminished.

Perioperative care of the infant with congenital heart disease.

The current approach to the perioperative management of the infant and child with congenital heart disease has been discussed. The major focus has been on potential problems of oxygen transport as they relate to vital organ system function. Management strategies for specific defects or perioperative problems have also been considered as well as the newer on-line monitoring techniques, while stressing the importance of careful clinical evaluation. The ultimate surgical outcome is dependent not only on the adequacy of repair or palliation but on the treatment of potential life-threatening situations that may take place during the critical postoperative period.