The role of chronotropic impairment during exercise after the Mustard operation.

To better understand the role of chronotropic impairment on exercise performance after the atrial switch (Mustard) operation, 20 patients who had undergone this operation for uncomplicated d-transposition of the great arteries exercised to maximal volition using a 1 min incremental treadmill protocol. Heart rate, oxygen consumption, carbon dioxide production and minute ventilation were monitored continuously. Two-dimensional echocardiograms were obtained before testing to calculate the right ventricular inflow volume indexed to body surface area. All patients achieved maximal aerobic capacity based on their ventilatory patterns and respiratory exchange ratio. Maximal heart rate was reduced (175 beats/min; 87% of predicted for age) and maximal oxygen consumption was decreased (31 ml/kg per min; 75% of predicted for age and gender). There was no correlation between maximal oxygen consumption and maximal heart rate. Right ventricular volume index, however, had a significant inverse correlation with maximal heart rate (r = -0.62, p less than 0.005). There was no correlation between right ventricular volume index and heart rate at rest. These results suggest that decreased maximal oxygen consumption in patients after the Mustard procedure is not a result of chronotropic impairment. Right ventricular dilation may be a compensatory response to chronotropic impairment.

Diagnosis, management, and long-term results of patients with congenital complete atrioventricular block.

Sixty-five patients with congenital complete atrioventricular block have been studied. The median age at time of diagnosis was 7 months with 26 infants being diagnosed prior to 1 month of age. Anatomic heart disease was present in 25/65 (39%) infants, with ventricular inversion/L-transposition of great arteries complex occurring in 20/25 infants (80%). The site of block was above the bundle of His in 11 of 18 (61%) patients studied, in the bundle of His in three of 18 (17%), and below the bundle of His in two of 18 (11%). Permanent pacemakers were implanted in 17 (26%). Ten patients (15%) have died. The highest risk was in patients with anatomic heart disease and patients diagnosed early in life.

Cardiopulmonary performance at rest and exercise after repair of total anomalous pulmonary venous connection.

Although long-term evaluations of patients after repair of total anomalous pulmonary venous connection have generally shown them to be clinically asymptomatic, assessment of their cardiovascular and pulmonary systems have been limited. Residual cardiopulmonary abnormalities undetected at rest may result in impaired function during exercise. To evaluate this hypothesis 9 patients underwent exercise testing after repair of total anomalous pulmonary venous connection. Pulmonary function testing was performed before exercise. Patients exercised using a 1-minute incremental bicycle or treadmill protocol monitoring heart rate, oxygen consumption, carbon dioxide production and minute ventilation. Compared with healthy children, the study patients had reduced maximal oxygen consumption and reduced oxygen consumption at ventilatory anaerobic threshold. Chronotropic response was impaired in 5 patients. Resting pulmonary functions showed evidence of mild restrictive lung disease. Breathing reserve was within normal limits. It is concluded that (1) aerobic capacity is mildly reduced after repair of total anomalous pulmonary venous connection, (2) chronotropic impairment is a common occurrence, and (3) pulmonary testing suggests mild restrictive lung disease that does not compromise exercise performance.

Relation of elevated plasma endothelin in congenital heart disease to increased pulmonary blood flow.

Endothelin-1 (ET), a potent vasoconstrictor peptide, has been found to be elevated in children with pulmonary hypertension associated with congenital heart defects. To evaluate the effect of pulmonary blood flow on ET concentrations, 5 ml blood samples were obtained peripherally at cardiac catheterization from 35 patients, ages 0.13 to 17 years (median 2). Plasma was extracted and ET measured by radioimmunoassay. Patients were classified into 2 groups based on the presence (group A) or absence (group B) of increased pulmonary blood flow defined as a Qp/Qs > or = 1.5. When the 13 patients (37%) in group A were compared with the 22 patients (63%) in group B there were no significant differences in age, cardiac index, or pulmonary and systemic resistances. ET concentrations were significantly higher in group A patients (median 3.25, range 0 to 16.5 vs median 0, range 0 to 6.35 pg/ml; p < or = 0.05). Pulmonary blood flow and pulmonary artery pressure were also higher in group A patients (p < or = 0.01). When patients within group A were subdivided into those with and without pulmonary hypertension, no difference was present in their ET concentrations (mean/SD: 4.4/4.3 vs 4.0/6.4 pg/ml, p = NS). Thus, ET is elevated in patients with congenital heart disease associated with left-to-right shunts and it appears that this increase is related to increased pulmonary blood flow independent of pulmonary artery pressure.

Sustained ventricular tachycardia after repair of tetralogy of Fallot: new electrophysiologic findings.

Ventricular arrhythmia originating from the outflow tract of the right ventricle is a presumed cause of late sudden death in patients after repair of tetralogy of Fallot. Exercise testing has been shown to enhance detection, and phenytoin has been shown to control ventricular arrhythmias in these patients. This study reports new findings in 3 patients who underwent electrophysiologic studies at postoperative cardiac catheterization; in each, sustained ventricular tachycardia was induced and found to originate from the inflow-septal area of the right ventricle. Using serial studies, the same sustained ventricular tachycardia was induced during therapeutic serum concentrations of phenytoin but not after propranolol. No patient had ventricular arrhythmia during a 24-hour electrocardiogram or during exercise. Although no patient had normal hemodynamic function, only 1 patient had right ventricular pressure greater than two-thirds systemic pressure. Each patient had undergone initial intracardiac repair at a relatively late age (3, 9, and 9 years).

Anomalous origin of circumflex coronary artery from right pulmonary artery: report of a rare anomaly.

A heretofore unreported anomaly of the coronary arteries in which a large circumflex artery arises from the pulmonary artery is described. The circumflex coronary artery in an 8-year-old girl was filled in a retrograde fashion via collaterals from a dominant left anterior descending coronary artery, and the right coronary artery was small and nondominant. Successful surgical correction of this defect was performed by use of total cardiopulmonary bypass and cardioplegic arrest. The orifice of the anomalous vessel and detached from the right pulmonary artery and implanted into the posterolateral aspect of the ascending aorta. Cardiopulmonary bypass with cardioplegic arrest is recommended for reconstruction of coronary arterial anomalies with abnormal sites of origin.

Delayed sternal closure after neonatal cardiac operations.

We retrospectively compared the use of primary elective open sternum coupled with delayed sternal closure with the use of primary sternal closure in neonates after cardiac operations. Primary elective open sternum/delayed sternal closure was selectively used in patients who demonstrated hemodynamic or respiratory deterioration, or both, during an intraoperative trial of sternal closure; otherwise primary sternal closure was used. Primary elective open sternum was used in 55 (61.8%) and primary sternal closure in 34 (38.2%) of the 89 patients studied. Eleven (20%) patients having primary elective open sternum died compared with 5 (14.7%) patients having primary sternal closure (p = 0.6). Six (10.9%) of the patients with primary elective open sternum died before delayed sternal closure; the remaining 49 patients comprise the primary elective open sternum/delayed sternal closure group. The durations of mechanical ventilation (9.7 +/- 0.9 days [mean plus or minus standard error of the mean], median 7.7 versus 9.9 +/- 3.4 days, median 4.9; p = 0.0005) and hospital stay (21.1 +/- 1.4 days, median 17.7 versus 19.6 +/- 4.1 days, median 12.9; p = 0.004) were shorter in the primary sternal closure group. The overall morbidity and duration of inotropic support were not significantly different between the two groups, although seven (20.6%) of the patients with primary sternal closure did have to undergo delayed sternal reopening for refractory postoperative low cardiac output. There was one superficial wound infection in the primary elective open sternum/delayed sternal closure group. Primary elective open sternum/delayed sternal closure is an effective treatment for postoperative neonatal mediastinal compression for the following reasons: (1) the morbidity is low; (2) the mortality of the critically ill group of neonates in whom primary elective open sternum/delayed sternal closure was used was similar to that of the less critically ill primary sternal closure group; and (3) 20.6% of the primary sternal closure group eventually had to undergo delayed sternal reopening to treat refractory postoperative low cardiac output.

Subclavian-coronary artery anastomosis in infancy for the Bland-White-Garland syndrome: a three-year and five-year follow-up.

Two infants, 4 months and 8 months of age, with anomalous origin of the left coronary artery, underwent direct anastomosis of the left subclavian artery to the left coronary artery. In the patient operated upon at 4 months of age, the anastomosis proved to be patent by angiographic study 3 years postoperatively. However, in the patient operated upon at 8 months of age, the study 5 years postoperatively revaled clinically unsuspected occlusion at the anastomosis site. After operation, both patients symptomatically improved. The heart size decreased on radiograms, the left ventricular ejection fraction improved, and the electrocardiographic abnormality resolved to a great extent. Since the preferred treatment for this abnormality and the ideal age for operation are yet to be established, long-term angiographic follow-up of all such surgically treated patients is needed. An advantage of the subclavian-coronary artery anastomosis is its applicability in the infant.

Extracorporeal membrane oxygenation for the circulatory support of children after repair of congenital heart disease.

We have treated 39 infants and children with congenital heart disease with extracorporeal membrane oxygenation during the past 5 years. Thirty-six were treated for low cardiac output or pulmonary vasoreactive crisis after repair of congenital heart defects. Twenty-two (61%) survived. Most patients were cannulated from the neck via the right internal jugular vein and the right common carotid artery. Six patients were cannulated from the chest, including three who had separate drainage of the left side of the heart with a left atrial cannula. Two of these patients survived and were the only survivors of the nine patients cannulated in the operating room because they could not be weaned from cardiopulmonary bypass after open cardiac operations. We also reviewed 312 patients (the predictor study series) having open cardiac operations before the availability of extracorporeal membrane oxygenation; 27 of these patients died. Data were collected at 1 and 8 hours postoperatively to determine if any parameters might predict early mortality. With these parameters used as criteria, patients who went on extracorporeal membrane oxygenation were as sick as those who died before extracorporeal membrane oxygenation was available. The most common complication was bleeding related to heparinization. The mean transfusion requirement in survivors was 1.50 +/- 1.13 ml/kg/hr, 5.63 +/- 7.0 ml/kg/hr in the nonsurvivors, and 7.46 +/- 8.29 ml/kg/hr in those cannulated in the operating room because they could not be weaned from bypass. Four children had intracranial hemorrhage, and two of them died. There was one late death. Nine of the 22 survivors are entirely normal. All survivors who do not have Down's syndrome are considered to have normal central nervous system function. We conclude that extracorporeal membrane oxygenation can improve survival in patients with both pulmonary artery hypertension and low cardiac output after operations for congenital heart disease.

Myocardial depression after elective ischemic arrest. Subcellular biochemistry and prevention.

The hemodynamic and cardiac biochemical effects of global ischemic arrest during cardiopulmonary bypass (CPB) were studied in 54 animals and compared to seven animals without ischemic arrest. Ischemic arrest alone reduced the first derivative of left ventricular force of contraction (LV dF/dt) to 52 percent of control 10 minutes after resuming function and to 64 percent after 1 hour of reperfusion. Cardiac output was depressed to 52 percent of control after 10 minutes of reperfusion, and to 74 percent of control after 60 minutes of reperfusion. In six animals, moderate hypothermia (26 degrees C.) resulted in no protection of cardiac function from ischemic arrest, whereas profound hypothermia to 18 degrees C. resulted in values of LV dF/dt and cardiac output nearly equivalent to the CPB control group (no arrest). A continuous infusion of a hyperkalemic hypothermic solution slightly improved the degree of protection over hypothermia alone. The sarcoplasmic reticulum (SR) isolated from hearts which had undergone 60 minutes of ischemic arrest bound significantly less calcium when the isolation was done after 10 minutes of reperfusion as well as when it was done after 60 minutes of reperfusion. The time to spontaneous release of calcium from the SR also was significantly longer. Moderate hypothermia did not result in improved SR function, whereas deep hypothermia induced by local cooling or by hypothermic potassium infusion retained SR function at normal levels. Oxidative phosphorylation of mitochondria isolated after 60 minutes of reperfusion was also depressed. The mitochondrial respiration rate after normothermic ischemic arrest was 155 natoms of oxygen per minutes versus 237 natoms for the hypothermic hyperkalemic group. Respiratory control index was 5.5 for the normothermic group versus 9.4 for the hypothermic group. It is concluded that hypothermia, whether effected by surface cooling or by hypothermic potassium infusion, allowed full recovery of hemodynamic and biochemical functions within 1 hour of reperfusion.

Down's syndrome, complete atrioventricular canal, and pulmonary vascular obstructive disease.

We reviewed our experience over a 10-year period to determine whether children with Down's syndrome and complete atrioventricular canal develop pulmonary vascular obstructive disease earlier than children with normal chromosomes and this defect. Comparisons were made between Down's syndrome and normal chromosome children regarding (1) pulmonary blood flow and pulmonary vascular resistance at initial catheterization, (2) operability as related to elevation in pulmonary vascular resistance, and (3) age at diagnosis of fixed pulmonary vascular obstructive disease. The 45 patients with Down's syndrome catheterized under 1 year of age had a lower mean pulmonary blood flow (3.2 versus 5.7; p = 0.0001) and higher mean pulmonary vascular resistance (8.3 versus 4.6 Wood units.m2; p = 0.0003) than their 34 normal chromosome counterparts. When all ages were included, 38 of 81 (47%) of the children with Down's syndrome and 32 of 40 (80%) of the normal children were considered operable. Non-Down's syndrome patients who had operations had a higher pulmonary blood flow (5.8 versus 3.3; p = 0.004) and lower pulmonary vascular resistance (3.6 versus 6.0 Wood units.m2; p = 0.005) than Down's syndrome patients. Of the 34 patients who did not have operations because of pulmonary vascular obstructive disease, 31 had Down's syndrome. In 10 of 81 children with Down's syndrome, fixed pulmonary vascular obstructive disease was diagnosed before the age of 1 year, while this was found in none of 40 normal children. Our data demonstrate that Down's syndrome patients with complete atrioventricular canal have a greater degree of elevation of pulmonary vascular resistance in the first year of life and more rapid progression to fixed pulmonary vascular obstructive disease than children with normal chromosomes.

The cost of congenital heart disease in children and adults. A model for multicenter assessment of price and practice variation.

OBJECTIVE: To assess the cost of congenital heart disease (CHD) and to assess whether practice pattern or price was more responsible for variation. RESEARCH DESIGN AND SETTING: Data were collected from Charleston, NC; Columbus, Ohio; Detroit, Mich; Houston, Tex; Los Angeles, Calif; and New York, NY. The CHD was first classified as to physiologic characteristics and severity. For each type of CHD, the number of clinic visits, hospitalizations, and years of medication use were estimated. RESULTS: On the basis of actual charges, the "prices" were calculated as follows, in 1992 dollars: for patients from birth to 21 years: benign disease (19% of patients), $3940; acyanotic disease (45%), $49,730; cyanotic disease (36%), $102,084; and average for all CHD categories, $59,877; for patients 22 to 40 years of age (of whom 24% had resolved defects or were dead): benign disease (19%), $3470; acyanotic disease (52%), $12,981; cyanotic disease (29%), $39,187; and average for all CHD, $18,773. The cost for the group from birth to 21 years varied from $47,500 to $73,600, accounting for 55% by practice (number of echocardiograms and cardiac catheterizations) and 45% by price, although mortality was similar. CONCLUSIONS: The treatment of CHD is comparatively inexpensive, especially in adult survivors. The variation in both practice and price bears further study, with comparison to determine the most cost-effective strategies for treating these patients.

Atrial natriuretic factor and sympathetic nervous output in response to volume shifts in the immature canine circulation.

This study evaluated the immature circulation's response to acute shifts in intravascular volume with respect to atrial natriuretic factor and plasma catecholamines. Serial measurements were performed on thirteen beagle puppies during volume expansion with a saline and albumin solution followed by volume contraction with furosemide. Atrial natriuretic factor correlated with right (r = .73, p less than 0.001) and left (r = .62, p less than 0.001) atrial pressures and increased to much greater levels than previously reported for mature animals. Simultaneously, 10 puppies had a progressive decrease in plasma norepinephrine over the 60-minute infusion (p less than 0.05) while two puppies demonstrated a marked increase between the 30- and 60-minute samples. Furosemide increased urine output and reversed the hormonal changes caused by volume expansion. Thus a greatly augmented output of atrial natriuretic factor occurs in the immature canine circulation in response to increased atrial and pulmonary pressures, while sympathetic output remains unchanged or falls with increasing intravascular volume until a critical decrease in cardiac output triggers a catecholamine surge.

Tetralogy of Fallot.

Tetralogy of Fallot is the most common malformation of children born with cyanotic heart disease, with an incidence of approximately 10 per cent of congenital heart disease. There can be a wide spectrum as to the severity of the anatomic defects, which include ventricular septal defect, aortic override, right ventricular outflow tract obstruction, and right ventricular hypertrophy. Cyanosis may vary from mild to severe, and patients may present as newborns or, more commonly, young infants. Infants with classic tetralogy of Fallot and stable anatomy should undergo primary complete intracardiac repair. The overall hospital mortality is approximately 3 to 5 per cent, with most patients who survive having an excellent clinical and hemodynamic result.

Intracardiac teratoma in a newborn.

Primary tumors of the heart are infrequent at all ages. We present a newborn with hypoxia and a heart murmur, in whom an echocardiogram revealed a large tumor filling the right ventricle and the pulmonary annulus. To maintain pulmonary blood flow, the patency of the ductus arteriosus was achieved by infusion of prostaglandin E1. Successful surgical resection was accomplished. The pathological examination was characteristic of a benign teratoma. The patient remains asymptomatic and has shown no evidence of recurrence of the tumor during a follow-up period of 34 months. This represents the eleventh case of intracardiac teratoma and only the fourth case to undergo successful surgical resection.