Cardiopulmonary performance during exercise in patients with repaired tetralogy of Fallot with absent pulmonary valve.

In patients with tetralogy of Fallot and absent pulmonary valve, the dilated pulmonary arteries sometimes result in bronchial compression and pulmonary symptoms due to airway obstruction, recurrent pulmonary infection, and development of bronchiectasis. After complete intracardiac repair, residual pulmonary disease may be expected to result in impaired cardiopulmonary performance during exercise. To assess this hypothesis, nine patients with tetralogy of Fallot and absent pulmonary valve underwent exercise testing and were compared to 38 patients with tetralogy of Fallot repaired using a transannular patch. All patients were exercised to maximum volition using a 1 minute incremental treadmill protocol with monitoring of pulmonary functions and expired gases. Maximal heart rate, maximal oxygen consumption, oxygen consumption at anaerobic threshold, and maximal respiratory exchange ratio were similar for the two groups. There was no significant difference for ventilation and gas exchange parameters at rest or at maximal exercise, and values for both groups were below the predicted normal for healthy subjects. Breathing reserve, however, did tend to be somewhat lower in the group with tetralogy of Fallot with absent pulmonary valve. In summary, despite significant preoperative symptoms, cardiopulmonary performance during exercise in patients with tetralogy of Fallot and absent pulmonary valve is similar to patients with tetralogy of Fallot repaired with a transannular patch.

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.

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.

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.

Congenital coronary artery fistulae: a review of 18 cases with special emphasis on spontaneous closure.

Between 1972 and 1990, 18 patients (median age 3 years, range 0.1-14 years) with coronary artery fistulae (CAF) were seen at this institution. Of the 16 patients without associated heart defects, two patients presented with congestive heart failure and the remaining 14 were asymptomatic. Fifteen patients had normal origin of two coronary arteries. Two patients had atresia of the proximal right coronary artery and, in one patient, the right coronary artery originated from the left main coronary artery. The QP/QS ranged between 1.0 and 2.8, with a mean of 1.4. Fifteen patients underwent operative closure without any deaths. One patient is being followed medically at present. Two patients showed spontaneous clinical improvement of CAF (complete closure in one and near complete in the other) and remained asymptomatic during a decade of follow-up. Review of the literature suggests operative closure of symptomatic and asymptomatic small CAF during childhood. However, the natural history of minute CAF remains unclear. In addition, symptoms from CAF may spontaneously improve with time.

The effects of rate responsive pacing on exercise performance in the postoperative univentricular heart.

Following the Fontan operation for definitive palliation of the univentricular heart, sinus node dysfunction, and/or atrioventricular block requiring pacemaker therapy is common. In previous studies ventricular rate responsive pacing (VVI,R) resulted in improved exercise performance over VVI pacing in anatomically normal hearts with either sinus node disease or atrioventricular block. In this study, the usefulness of both VVI,R and DDD,R pacing are evaluated in the postoperative univentricular heart following the Fontan operation. Eight postoperative Fontan patients with sinus node disease or atrioventricular block underwent exercise testing using a treadmill protocol. Six patients had single chamber ventricular pacemakers and two patients had dual chambered rate responsive pacemakers. Median age at exercise testing was 14 years. Patients were tested in the VVI, VVI,R, and DDD,R modes acting as their own controls. Heart rate, work rate, oxygen consumption, and respiratory exchange ratio were monitored continuously. Heart rate was significantly increased in the rate responsive modes compared to the VVI mode. In spite of the significant increase in heart rate, there was no change in maximal work rate or oxygen consumption. There was also no significant change in oxygen consumption at ventilatory anaerobic threshold. From these data we would conclude that VVI,R pacing in postoperative univentricular hearts does not result in improved exercise performance and that further study with DDD,R pacing is needed to determine its usefulness in this group of patients.

Acute changes in endothelin-1 after hemodialysis for chronic renal failure.

Endothelin is a recently described, potent renal vascular and systemic vasoconstrictor peptide. To evaluate the response of this peptide to volume contraction, we measured eight baseline and posthemodialysis samples from seven children, aged 14.5 +/- 3 years, with chronic renal failure. Plasma was extracted and endothelin-1 was measured by radioimmunoassay. Dialysis was performed for a 3- to 3 1/2-hour period, and body weight decreased from 38.0 +/- 14.3 to 36.2 +/- 13.8 kg (p < 0.01) during this time. There were no significant changes in heart rate or respiratory rate after dialysis, but blood pressure fell from 127/80 +/- 22/16 to 114/72 +/- 20/21 mm Hg (p = 0.05 for the systolic pressure). Plasma endothelin-1 concentration increased from 1.5 +/- 1.2 pg/ml at baseline to 7.3 +/- 8.9 pg/ml (p = 0.06) after dialysis; the fall in body weight from dialysis correlated with the increase in endothelin (r = -0.75; p = 0.05). Thus volume contraction from hemodialysis is associated with a rise in plasma endothelin-1, which is related to the acute change in body weight.

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.

Augmented norepinephrine and renin output in response to maximal exercise in hypertensive coarctectomy patients.

To evaluate a possible neural or renal contribution to the hypertension that occurs in some patients following coarctation of aorta repair, 35 patients underwent graded bicycle exercise with serial measurements of plasma norepinephrine concentrations and plasma renin activity. Sixteen patients with coarctectomy who had systolic or diastolic hypertension at peak exercise were compared with 19 normotensive patients with coarctectomy. The average time interval between coarctation repair and study was significantly longer (p less than 0.05) in the hypertensive group than in the normotensive patients (12.8 +/- 4.8 versus 8.7 +/- 2.2 years). The heart rate response to exercise was similar for both patient groups. The systolic blood pressure in the hypertensive group was higher than in the normotensive group at rest in the supine and upright positions and at 5 minutes of recovery, in addition to peak exercise, and the diastolic blood pressure was increased at peak exercise. Plasma norepinephrine concentrations were significantly higher at peak exercise and during recovery in the hypertensive group than in the normotensive patients. Plasma renin activity was also significantly higher in the hypertensive group at peak exercise. These data suggest that patients with coarctectomy who have a hypertensive response to exercise have an augmented sympathetic nervous system output and increased plasma renin activity that may lead to peripheral vasoconstriction at peak exercise and that may contribute to the development of their hypertension.

Grading the severity of congestive heart failure in infants.

To determine which variables most accurately define congestive heart failure (CHF) in infants, 41 patients (median age 2.5 months) were graded by four pediatric cardiologists for the presence and severity of CHF based on the following variables: amount of formula consumed per feeding, feeding time, history of diaphoresis or tachypnea, growth parameters, respiratory and heart rates, respiratory pattern, perfusion, presence of edema, diastolic filling sounds, and hepatomegaly. There were 19 patients graded as having no CHF, nine as mild, seven moderate, and six severe CHF. The most sensitive and specific variables (p less than 0.0001) for the presence of CHF were a history of less than 3.5 oz/feed, respiratory rate greater than 50/min, an abnormal respiratory pattern, diastolic filling sounds, and hepatomegaly. Moderate to severe CHF was present when patients took less than 3 oz/feed or greater than 40 min/feed, had an abnormal respiratory pattern with a resting respiratory rate greater than 60/min, and had a diastolic filling sound and moderate hepatomegaly. Severe CHF was accompanied by a heart rate greater than 170/min, decreased perfusion, and severe hepatomegaly. Thus, the grading of the severity of CHF in infants should include an accurate description of these historical and clinical variables.

Failure of rate responsive ventricular pacing to improve physiological performance in the univentricular heart.

The physiological efficacy of single chamber, rate responsive ventricular pacing (VVIR) is unknown for symptomatic patients following the Fontan procedure for univentricular hearts. A total of six postoperative children, ages 6-21 years (mean 13), with symptomatic bradycardia requiring pacing therapy, underwent comparative treadmill exercise testing in randomized fixed rate (VVI) and VVIR pacing modes. In all instances, implanted activity pulse generators (Medtronic Model 8403) were programmed to identical age-appropriate low paced rates during VVI and VVIR modes with the upper rate response at 150 ppm. All studies were performed at least 2 weeks apart. Physiological values of heart rate, blood pressure, work rate (watts), oxygen consumption (VO2), carbon dioxide production (VCO2), and respiratory exchange ratio (RER) were monitored continuously during each test using a 1 minute incremental treadmill protocol. Ventilatory anaerobic threshold (VAT) was calculated from VO2, VCO2, and minute ventilation. The results demonstrated that although there was a significant increase in paced heart rate per minute throughout exercise (P less than 0.01) with VVIR pacing, maximum watts, VO2, and VAT remained unchanged. These findings indicate that in spite of an improved chronotropic response to exercise, children with univentricular hearts following the Fontan procedure continue to demonstrate altered hemodynamics which negate potential benefits of VVIR pacing.

Pharmacologic therapy for fetal arrhythmias.

Although great strides have been made in diagnosing fetal cardiac anatomic and functional abnormalities, in utero cardiac therapy is limited to the treatment of significant arrhythmias. The fetal prognosis may change if the dysrhythmia persists or if the condition results in intrauterine heart failure. When either complication is evident, intrauterine drug therapy may be indicated if the fetus is considered too immature for delivery. Information from case reports has shown several drugs to be useful to cardiovert the fetus, with digitalis being the pharmacologic agent used most often. At present, treatment consists mainly of transplacental administration of antiarrhythmic agents with the object of normalizing FHR and rhythm and abolishing, or preventing, fetal cardiac failure. Various agents have been used with variable success. More direct fetal therapy by intramuscular injection or umbilical vein infusion may replace unsuccessful indirect maternal therapy. It is unclear why some fetuses respond (or appear to respond) and others have hydrops and die in the absence of congenital heart disease or documented infection. With proper therapy, many fetuses survive and have a satisfactory prognosis, depending on the form of arrhythmia and the nature of any cardiac structural defects.