Responses of non-obese white children to treadmill exercise.

OBJECTIVE: To determine the response to maximal treadmill exercise with the Bruce protocol in a cohort of healthy non-obese American children and adolescents. STUDY DESIGN: A retrospective review of treadmill exercise studies on 347 white American children (188 boys, 159 girls) aged 5 to 18 years was performed with metabolic criteria to verify maximal exercise effort. Data on exercise endurance time, heart rate, blood pressure, and metabolic variables were assessed and compared between age groups and sexes by unpaired t testing and analysis of variance. RESULTS: Exercise endurance time was lower in all age groups when compared with earlier published data. Girls had a lower endurance time than boys at all ages. There was no significant difference in maximum heart rate with respect to age or sex. The maximum systolic blood pressure and diastolic blood pressure increased with increasing age in both boys and girls. Boys had significantly higher maximum systolic blood pressure and diastolic blood pressure after 13 years of age. The maximum absolute oxygen consumption and indexed oxygen consumption showed similar trends for both sexes. CONCLUSION: Lower exercise endurance times are seen despite physiologic evidence of maximal effort, raising the possibility that cardiovascular conditioning is reduced in contemporary American children.

Procainamide for rate control of postsurgical junctional tachycardia.

This study was conducted to determine the efficacy of procainamide therapy for rapid rate control of postoperative junctional tachycardia (JT). Postoperative JT is one of the most difficult forms of tachycardia to manage. Reported success with a variety of treatments of JT in infants and children has been inconsistent and limited. Rate control using procainamide was achieved in 17 children having rapid JT (heart rate >200 beats/min) between 1986 and 1997. In the first 5 patients (protocol A), following a loading dose of 3 mg/kg over 20 minutes, a continuous procainamide infusion was initiated at a rate of 20 microg/kg/min. The infusion dose was increased in 10 microg/kg steps every 30 minutes to 40-120 microg/kg/min until the heart rate decreased below the target rate of 180 beats/min. In the other 12 patients (protocol B), after a higher loading dose of 10 mg/kg the infusion rate was increased every 10-15 minutes until the heart rate decreased below the target rate of 180 beats/min. Procainamide decreased JT rates in all patients but the response was significantly faster in protocol B. In the patients treated with protocol A, pretreatment JT rates ranged from 203 to 240 (213+/-17) beats/min and decreased to 195+/-10 beats/min at 2 hours (p = ns), 186+/-8.8 at 4 hours (p<0.02), and 179+/-8 at 6 hour postinitiation of PA. In protocol B, pretreatment JT rates ranged from 201 to 240 (218+/-17) beats/min and decreased to 183+/-20 beats/min at 2 hours (p<0.001) and 171+/-12 at 4 hours after starting the procainamide therapy. The mean duration to decrease JT rates below the target rate of 180 beats/min was 3.2+/-1.1 hours in protocol B compared to 6.4+/-3.8 hours in protocol A (p<0.02). Eight of 12 patients in protocol B achieved rate control below the target rate of 180 beats/min within 4 hours despite remaining on significant inotropic support. The procainamide infusion rates to maintain heart rates below 180 beats/min were 40-120 (68.4+/-22.1) microg/kg/min. No proarrhythmia, bradycardia, or significant hypotension was observed. In this series procainamide provided safe, effective, and rapid rate control of JT occurring in the immediate postoperative period.

Effect of preterm birth on pulmonary function at school age: a prospective controlled study.

OBJECTIVE: To assess long-term pulmonary outcome of a regional cohort of children born at < 32 weeks' gestation compared with a matched term control group. STUDY DESIGN: All 125 surviving children born at 24 to 31 weeks' gestation during a 1-year period and a sociodemographically matched term control group were evaluated at age 7 years. RESULTS: Preterm children with previous bronchopulmonary dysplasia (BPD) were twice as likely to require rehospitalization during the first 2 years of life than were preterm children without BPD (53% vs 26%, P < .01). At 7 years of age the BPD group had more airway obstruction than did both preterm children without BPD and the term control group (significantly reduced mean forced vital capacity, forced expiratory volume in 1 second, and forced expiratory flow, 25% to 75% vital capacity, all, P < .001). Lung function among preterm children without previous BPD was similar to that of the term control group. Bronchodilator responsiveness was observed twice as often in preterm children with previous BPD (20 of 43, 47%) compared with preterm children without BPD (13 of 53, 25%) or the term control group (23 of 108, 21%, P < .001). These differences remained significant after adjustment was done for birth weight and gestational age. CONCLUSION: Preterm children without BPD demonstrate pulmonary function at school age similar to that of children in a healthy term control group, whereas preterm children with previous BPD demonstrate abnormal pulmonary function.

Double-outlet right ventricle (tetralogy of Fallot type) associated with anomalous origin of the left coronary artery from the right pulmonary artery: report of successful total repair in a 2-month-Old infant.

The case reported herein demonstrates the rare association of double-outlet right ventricle (tetralogy of Fallot type) with anomalous origin of the left coronary artery from the pulmonary artery. It is the first reported successful total surgical repair in an infant.

In utero management of hydrops fetalis caused by critical aortic stenosis.

Hydrops fetalis is rarely associated with congestive heart failure caused by obstructive left-sided heart lesions. There are rare cases of live born neonates with critical congenital valvar aortic stenosis and hydrops reported in the literature, all with fatal outcomes. This report describes, to the best of our knowledge, the first two newborns who were diagnosed prenatally to have hydrops fetalis caused by critical valvar aortic stenosis, who were treated prenatally with digoxin and who postnatally had successful percutaneous balloon aortic valvuloplasty. Both patients had not only left but right ventricular dysfunction. We speculate that right ventricular dysfunction was a contributing factor in the development of hydrops in these patients and in utero medical therapy with digoxin is associated with resolution of the hydrops before delivery.

Exaggerated blood pressure response to exercise in children with increased low-density lipoprotein cholesterol.

Arterial vascular responses are characteristically altered with hypercholesterolemia: conduit vessels manifest increased stiffness, and conduit and resistance vessels demonstrate impaired endothelium-dependent dilation and augmented vasoconstriction to neurohumoral stimulation. These changes should be reflected in an exaggerated blood pressure increase in response to exercise. To evaluate this hypothesis, we compared the blood pressure response to treadmill exercise in children with hypercholesterolemia and children with normal lipid levels. In a preliminary retrospective study, 15 hypercholesterolemic boys 10 to 18 years old underwent treadmill exercise testing, and their blood pressure results were compared with those of 32 normolipidemic children in the same age group who had undergone treadmill exercise electively in the same time period. In the second phase, 10 hypercholesterolemic boys and 10 normolipidemic age-matched boys were evaluated prospectively according to the same protocol. Treadmill exercise involved a modified Bruce protocol with heart rate and blood pressure measured before exercise, immediately after exercise, and throughout recovery. Office blood pressures were normal in all children, with no significant difference between groups. With treadmill exercise, all subjects achieved >95% of predicted maximum heart rate and endurance times, maximum oxygen consumption, and maximum respiratory ratio did not differ between groups. Results of the retrospective and prospective groups were similar and were therefore combined. Children with increased low-density lipoprotein (LDL) cholesterol had significantly higher systolic and diastolic blood pressures immediately before treadmill exercise (systolic 120 +/- 13 mm Hg vs 113 +/- 13 mm Hg, p < 0.03; diastolic 68 +/- 8 mm Hg vs 63 +/- 9 mm Hg, p < 0.01). After exercise, blood pressures were again significantly higher in the subjects with high LDL cholesterol (systolic 182 +/- 20 mm Hg vs 160 +/- 23 mm Hg, p < 0.0003; diastolic 77 +/- 12 mm Hg vs 72 +/- 9 mm Hg, p < 0.03). At the end of recovery, systolic blood pressures remained significantly higher in subjects with high LDL cholesterol (120 +/- 9 mm Hg vs 112 +/- 12 mm Hg, p < 0.005). In this study, children with severely increased LDL cholesterol had an exaggerated blood pressure response to exercise when compared with normolipidemic control subjects. The study findings suggest that control of arterial vascular tone may already be altered in children with hypercholesterolemia.

Postoperative assessment of a modified surgical approach to repair of tetralogy of Fallot. Long-term follow-up.

BACKGROUND: After repair of tetralogy of Fallot, right ventricular (RV) dilation has been associated with increased risk of ventricular arrhythmias and sudden death. To address this, a modified repair was developed. METHODS AND RESULTS: We followed two postoperative groups: group 1 (n = 20) received repair of tetralogy of Fallot with the modified technique with transatrial ventricular septal defect closure, a short infundibular incision with avoidance of muscle resection, and patch expansion of the RV outflow tract; group 2 (n = 22) received repair of tetralogy of Fallot by the traditional technique with ventricular septal defect closure through a ventriculotomy with resection of obstructing muscle. Six patients were excluded from further follow-up: two patients, one in each group, who required RV-pulmonary artery conduit placement at original repair; one patient in group 1 who developed double-chamber RV; and three patients, two in group 1 and one in group 2, who were lost to our follow-up < 5 years postoperatively. We compared postoperative findings > 10 years after repair. Despite similar residual RV outflow tract stenosis and obligatory pulmonary insufficiency by examination and Doppler echocardiography, RV size was smaller in the modified group, as reflected by RV/left ventricle on M-mode echocardiography (0.66 +/- 0.22 versus 0.81 +/- 0.17, P = .02), cardiothoracic ratio (0.53 +/- 0.04 versus 0.58 +/- 0.06, P = .03), and QRS duration (126 +/- 19 versus 143 +/- 23, P = .03). RV systolic function was more impaired in group 2, as reflected by decreased systolic tricuspid annulus excursion on two-dimensional echocardiography. Exercise endurance time was significantly higher in group 1 patients. Lown grade 4 ventricular ectopy on ambulatory ECG was present in three patients in group 2 and none in group 1. CONCLUSIONS: The modified technique results in significantly less RV dilation and better preservation of RV function at late follow-up.

Loss of sinus rhythm after total cavopulmonary connection.

BACKGROUND: Total cavopulmonary connection (TCPC) to repair functional single ventricle involves the sinus node area, in contrast to the Fontan procedure. We compared ECG findings after TCPC and Fontan to evaluate the impact of the cavopulmonary connection on sinus rhythm postoperatively. METHODS AND RESULTS: The Fontan group consisted of 17 patients repaired at 7.8 +/- 3.1 years of age (mean +/- SD): 11 for tricuspid or pulmonary atresia (TA/PA) and 6 for single ventricle. The TCPC group consisted of 19 patients repaired at 5.1 +/- 3.2 years of age (mean +/- SD) (P < .001): 9 for TA/PA, 4 for single ventricle, and 6 for hypoplastic left heart syndrome. Mean follow-up after Fontan was 7.7 +/- 2.7 years versus 2.8 +/- 1.6 years for TCPC (P < .001). Preoperative ECGs on all TCPC patients showed sinus rhythm (SR), whereas 16 of 17 Fontan patients had SR and one had nonsinus atrial rhythm (NSAR) since birth. On the first postdischarge ECG, 12 of 19 TCPC patients (63%) were in SR, 4 were in junctional rhythm (JR), and 3 were in NSAR. In comparison, 15 of 17 Fontan patients (88%) were in SR with 1 of 17 in NSAR and 1 in supraventricular tachycardia (P < .05 with chi 2 test). By 2 years postoperatively, only 6 of 15 TCPC patients available for follow-up (40%) were in SR, with 7 of 15 in JR and 2 of 15 in NSAR. By contrast, 13 of 17 Fontan patients (76%) remained in SR, with 1 in NSAR and 3 in JR (P < .05 with chi 2 test). TCPC patients with loss of SR did not differ from other patients in the group in age at repair, preoperative diagnosis, or surgeon performing the procedure. CONCLUSIONS: This significant incidence of loss of SR temporally related to surgery suggests that operative compromise of the sinus node area is common with TCPC.

Modified technique for balloon valvuloplasty of critical pulmonary stenosis in the newborn.

OBJECTIVES: We report our experience in eight consecutive neonates who underwent attempted balloon dilation as an initial therapy for critical valvular pulmonary stenosis, and we review in detail technical modifications that improved the success rate. BACKGROUND: Balloon dilation of the pulmonary valve has become the treatment of choice for valvular pulmonary stenosis in children and adults. There are few reports of its effectiveness in critical pulmonary stenosis in the newborn. In this setting, application of the technique of balloon dilation has been limited by the ability to advance the necessary guide wires and catheters across the stenotic, often near-atretic, pulmonary valve. METHODS: The pulmonary valve was crossed in all patients. When this could not be accomplished with an end-hole catheter, a soft guide wire was advanced directly across the pulmonary valve through the end-hole catheter positioned in the right ventricular outflow tract below the valve. Initial predilation was achieved in all patients by using a coronary dilation catheter in an effort to facilitate introduction of the definitive balloon dilation catheter. Definitive dilation with a balloon diameter of > or = 110% of the diameter of the pulmonary valve annulus was possible in six patients. RESULTS: Right ventricular pressure declined from a mean value of 108 +/- 32 mm Hg to a mean value of 49 +/- 11 mm Hg after balloon dilation, with no change in heart rate or aortic pressure in these six patients after definitive balloon dilation. CONCLUSIONS: The results of this small series suggest that critical valvular pulmonary stenosis in the newborn can be successfully treated by transluminal balloon valvuloplasty.

The changing pattern of infective endocarditis in childhood.

Forty-eight cases of infective endocarditis (IE) that occurred in 42 patients with congenital heart disease were reviewed from 1970 through 1990 and were compared with a 20-year review of 108 cases diagnosed between 1953 and 1972. The review demonstrates that the natural history of IE in children has changed over the last 2 decades, with half of the cases occurring after surgery for congenital heart disease. In the postoperative group, 46% of patients had undergone valve replacement and 7 of these (29%) had a right ventricular to pulmonary artery valved conduit as the site for IE, suggesting significant additional risk in this setting. Among patients with nonsurgically treated congenital heart disease and IE, mitral valve prolapse has emerged as an important underlying heart lesion occurring in 29% of patients. The bacterial spectrum has shifted, with a significant increase in the incidence of uncommon causative organisms. Mortality has continued to decline with survivorship of 90% in this series.

Late pulmonary venous obstruction after surgical repair of infradiaphragmatic total anomalous pulmonary venous return.

Twelve years after an apparently successful surgical correction of infradiaphragmatic (obstructed) total anomalous pulmonary venous drainage, a 12-year-old boy developed evidence of pulmonary artery hypertension secondary to pulmonary venous obstruction due to an apparent lack of growth at the anastomotic site.

Results of balloon valvuloplasty in the treatment of congenital valvar pulmonary stenosis in children.

Transluminal balloon valvuloplasty was used in the treatment of congenital valvar pulmonary stenosis in 19 children, aged 5 months to 18 years. The right ventricular (RV) systolic pressure and RV outflow tract gradient decreased significantly immediately after the procedure (95 +/- 29 vs 59 +/- 14 mm Hg, p less than 0.01, and 78 +/- 27 vs 38 +/- 13 mm Hg, p less than 0.01). Seven of these patients were evaluated at cardiac catheterization 1 year after balloon valvuloplasty. No significant change occurred in RV systolic pressure or RV outflow tract gradient at follow-up evaluation compared with measurements immediately after balloon valvuloplasty (60 +/- 5 mm Hg vs 56 +/- 12 mm Hg and 39 +/- 5 vs 38 +/- 10 mm Hg). In addition, follow-up evaluation was performed using noninvasive methods and included electrocardiography (n = 13), vectorcardiography (n = 11) and Doppler echocardiography (n = 11) Doppler echocardiography in 11 patients 15 +/- 9 months after balloon valvuloplasty showed a continued beneficial effect with a mild further decrease in RV outflow tract gradient. Thus, balloon valvuloplasty is effective in the relief of pulmonary stenosis.

Hemodynamic determinants of exercise-induced ST-segment depression in children with valvar aortic stenosis.

To evaluate the hemodynamic factors associated with treadmill-induced ST-segment depression in children with valvar aortic stenosis, 12 patients (mean age 13 years) with ST-segment depression during treadmill exercise and 5 patients (mean age 13 years) without ST-segment depression during treadmill exercise underwent exercise testing during cardiac catheterization. The left ventricular (LV) systolic pressure and LV outflow tract gradient at rest (177 +/- 25 vs 138 +/- 8 mm Hg and 59 +/- 18 vs 23 +/- 7 mm Hg, respectively) and corresponding pressures during maximal supine exercise (248 +/- 37 vs 189 +/- 17 mm Hg and 112 +/- 34 vs 52 +/- 14 mm Hg) were significantly greater (p less than 0.01) in the patients with exercise-induced ST-segment depression, although overlap existed. The LV-O2 supply-demand ratio during maximal supine exercise was significantly less (6.4 +/- 2.7 vs 11.8 +/- 0.7; p less than 0.005) in patients with than in those without exercise-induced ST-segment depression. In fact, an LV-O2 supply-demand ratio less than 11.0 was 100% sensitive and specific in predicting treadmill-induced ST-segment depression. These results suggest that although the development of ST-segment depression during treadmill exercise is related to LV systolic pressure and LV outflow gradient, its major hemodynamic determinant is the LV-O2 supply-demand ratio.

Percutaneous balloon valvuloplasty for treatment of congenital pulmonary valvular stenosis in children.

Percutaneous balloon pulmonary valvuloplasty was performed in seven children with moderate to severe valvular pulmonary stenosis (right ventricular to pulmonary artery pressure gradient greater than 50 mm Hg). All patients experienced a decrease in right ventricular peak systolic pressure from 108 +/- 30 to 60 +/- 5.6 mm Hg (p less than 0.001), decrease in right ventricular to pulmonary artery gradient from 90.1 +/- 30 to 38.8 +/- 5 mm Hg (p less than 0.001) and increase in pulmonary valve area from 0.33 +/- 0.06 to 0.55 +/- 0.15 cm2/m2 (p less than 0.001). In the two patients who underwent supine bicycle exercise before and after valvuloplasty, a significant decrease in both the maximal right ventricular peak systolic pressure (212 to 140 and 175 to 125 mm Hg, respectively) and in right ventricular to pulmonary artery peak pressure gradient (185 to 110 and 151 to 85 mm Hg, respectively) occurred. All patients tolerated the procedure well and no serious complications were observed. It is concluded that percutaneous balloon valvuloplasty is a safe and effective method for relief of right ventricular obstruction due to moderate or severe valvular pulmonary stenosis. However, long-term results remain unknown.