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.     

Ventricular tachycardia in children

Thirty-eight patients aged 1 to 20 years (mean 11.2) were evaluated because of recurrent ventricular tachycardia. The follow-up period ranged from 0.5 to 12 years (mean 6). The patients were separated into two groups according to the presence or absence of known structural heart disease. Seventeen of the 21 patients with known heart disease were symptomatic (cardiac arrest in 5, syncope in 5, dizziness in 7) compared with only 6 of the 17 patients without heart disease (syncope in 3 and dizziness in 3) (p <0.01). All symptomatic patients had ventricular tachycardia with rates of more than 150 beats/min, whereas all but one of the asymptomatic patients had rates of less than 150 beats/min (p <0.01). Graded treadmill exercise testing was performed in 21 of the 38 patients. Exercise increased the degree of ventricular arrhythmia in 8 of the 11 symptomatic patients but decreased or abolished the arrhythmia in 9 of the 10 asymptomatic patients (p <0.01).Antiarrhythmic therapy was used in 28 of the 38 patients. Effectiveness of therapy was assessed with both 24 hour Holter monitoring and graded treadmill exercise testing. Therapy effectively abolished ventricular tachycardia and greatly decreased the number of premature ventricular complexes in the symptomatic patients but was less effective in the asymptomatic patients. Thus, this study suggests that the presence of underlying heart disease, the rate of ventricular tachycardia and the results of graded treadmill exercise tests are important in predicting the prognosis of children with ventricular tachycardia.     

Cardiovascular effects of breathing 95 percent oxygen in children with congenital heart disease

The hemodynamic effects of breathing 95% oxygen were evaluated in 26 children with congenital heart disease. Aortic, pulmonary arterial, right atrial, and pulmonary arterial wedge pressure, aortic and pulmonary artery oxygen saturation, and blood gas, cardiac index, and heart rate were measured in room air and after each patient had breathed 95 % oxygen for 10 (n = 26) and 20 (n = 5) minutes. Measurements were repeated with the patient again breathing room air for 10 (n = 11) and 20 (n = 6) minutes. After 10 minutes of 95% oxygen, arterial partial pressure of oxygen increased from 85 ± 13 to 420 ± 89 torr (p < 0.001). Aortic mean pressure increased from 80 ± 10 to 83 ± 10 mm Hg (p < 0.01), and systemic vascular resistance increased from 20 ± 7 to 26 ± 8 U (p < 0.001). The cardiac index decreased by 21 % from 3.96 ± 0.94 to 3.12 ± 0.74 liters/min/m² (p < 0.001) and the stroke index decreased by 11% (p < 0.001). A 23% decrease in oxygen consumption (p < 0.001) was observed, and oxygen transport decreased from 763 ± 179 to 600 ± 161 ml O₂/min/m² (p < 0.001). Cardiac index, stroke index, and systemic vascular resistance did not return to normal until 20 minutes after cessation of oxygen breathing. To determine whether reflex bradycardia is responsible for these oxygen-induced hemodynamic changes, heart rate was kept constant by atrial pacing in a second group of 5 patients. In these children, significant decreases in cardiac index, stroke index, and oxygen consumption, and increases in systemic vascular resistance also occurred with 95% oxygen. Thus, in children with acyanotic congenital heart disease, hyperoxia increases aortic pressure and systemic vascular resistance and decreases cardiac index, stroke index, oxygen consumption, and oxygen transport.     

Altered baroreceptor function in children with systolic hypertension after coarctation repair

To determine whether altered baroreceptor function may contribute to systemic hypertension after coarctation of the aorta (C of A) repair, baroreceptor function was evaluated in 6 children with repaired C of A mild arm systolic hypertension. Data were compared with those from 7 normotensive control children with hemodynamically mild heart disease. Age at C of A repair averaged 9.9 ± 3.1 years (mean ± standard deviation [SD]). Arm systolic pressure was 143.8 ± 2.9 mm Hg in the C of A repair group, compared with 118.3 ± 9.9 for control subjects (p < 0.001). At catheterization, steady-state sigmoidal baroreceptor function curves relating mean arterial pressure to R-R interval were derived by increasing and decreasing mean arterial pressure with small injections of phenylephrine and nitroprusside. Compared with control subjects, the baroreceptor function curves of children with repaired C of A (1) are reset about a higher baseline mean arterial pressure (108.8 ± 6.6 versus 90.3 ± 8.6 mm Hg, p < 0.01), (2) have a decreased slope (7.9 ± 3.7 versus 17.4 ± 3.6 ms/mm Hg, p < 0.001), and (3) have a diminished R-R interval range (246.7 ± 81.5 versus 535.7 ± 97.2 ms, p < 0.001). Thus, in children with hypertension after C of A repair, the baroreflex is reset to an elevated mean arterial pressure level and has a diminished sensitivity to changes in arterial pressure.     

Reoperation for coarctation of the aorta

Between 1957 and 1980 reoperation for coarctation of the aorta was performed in 21 patients at one institution for an overall incidence rate of 7.9 percent. The incidence rate of reoperation was 38 percent for patients younger than age 3 years and 1.5 percent for patients 3 years or older at initial repair. Before reoperation 14 of the 21 patients were symptomatic, 19 had systolic hypertension of the upper limbs and 20 had a documented coarctation pressure gradient at rest (mean 42.4 mm Hg). Surgical techniques used at reoperation were patch aortoplasty in 12 patients, graft interposition in 4, end to end anastomosis in 3 and end to side left subclavian to descending aorta bypass graft in 2. There was one surgical death. The 20 survivors have been followed up a mean of 4.3 years. There has been significant symptomatic improvement (p < 0.001). Upper limb hypertension has also lessened significantly (p < 0.001) after reoperation;15 patients are no longer hypertensive and 3 have a lesser degree of hypertension. The coarctation pressure gradient at rest has significantly decreased (p < 0.001); 13 patients have no residual gradient and 7 have a mild gradient of 20 mm Hg or less. Graded treadmill exercise testing performed in five patients after reoperation documented upper limb hypertension in four and a marked increase in coarctation gradient with exercise in three.

In conclusion, the incidence of reoperation is significantly increased in patients who are younger than age 3 years at initial coarctation repair. Reoperation is a safe and effective procedure. It has a low mortality rate (4.8 percent), relieves symptoms and decreases hypertension and the coarctation pressure gradient. Patch aortoplasty appears to be the operative procedure of choice. Moderate to severe hemodynamic abnormalities may persist during exercise after reoperation for coarctation of the aorta.     

Hemodynamic abnormalities in response to supine exercise in patients after operative correction of tetrad of fallot after early childhood

The exercise hemodynamic values in two groups of patients with repaired tetrad of Fallot (eight patients with some residual pulmonary insufficiency and seven patients without insufficiency) were compared with values in seven patients with trivial pulmonary stenosis who had not been operated on. The patients with tetrad of Fallot underwent surgery after age 8 years and all had a good hemodynamic repair (no shunts and a right ventricular systolic pressure at rest of less than 60 mm Hg). Exercise increased the right ventricular outflow tract gradient by the same magnitude in all three groups of patients. However, both surgically treated groups experienced impaired cardiac pump function on supine exercise (that Is, a lower than anticipated cardiac Index for the amount of oxygen consumed and a significant decrease in stroke Index). Exercise also caused both groups with repair to have a decrease in stroke Index and a concomitant increase in right ventricular end-diastolic and pulmonary wedge pressures; in contrast, the patients with pulmonary arterial stenosis had an Increase in stroke index and a concomitant decrease in right ventricular end-diastolic and pulmonary wedge pressures.These findings Indicate that an impaired cardiac response to supine exercise can occur in patients In whom Intracardlac repair of tetrad of Fallot was performed after early childhood, even though they have had a good hemodynamic repair. In addition, the impaired cardiac response to supine exercise in these patients was probably due largely to an altered myocardial compliance rather than to either residual pulmonary stenosis or pulmonary insufficiency.     

Intravascular hemolysis associated with porcine mitral valve calcification in children

Intravascular hemolysis was present in 5 of 16 children who underwent porcine valve replacement. Each patient had an abnormal blood smear pattern and reticulocytosis and one or more biochemical changes indicative of hemolysis. In all five patients, the porcine valve was calcified. Cardiac catheterization demonstrated severe mitral stenosis and minimal mitral insufficiency in each of the patients with intravascular hemolysis. The presence of hemolysis is indicative of valve dysfunction.     

Chronic verapamil therapy in pediatric and young adult patients with hypertrophic cardiomyopathy

Oral verapamil, 5.2 +/- 1.1 mg/kg/day (range 2.8 to 7), was administered to 13 pediatric patients with hypertrophic cardiomyopathy for 13 +/- 6 months (range 2 to 20). The patients had significant symptomatic improvement on verapamil therapy. Murmur intensity diminished in 6 patients during therapy and left ventricular (LV) electromotive forces on the electrocardiogram diminished in 4, increased in 5 and did not change in 4. Exercise endurance increased from 8.4 +/- 3.9 to 10.9 +/- 2.8 minutes (p less than 0.01). Seven patients had ST-segment depression (0.38 +/- 0.28 mV) before verapamil therapy, which improved after verapamil therapy in 5 (0.24 +/- 0.17 mV, p less than 0.02). Of 4 patients with exercise-induced ventricular ectopic activity, 3 had diminution or abolishment of ectopy following verapamil. By echocardiography, the patients had an increase in LV end-diastolic dimension from 3.4 +/- 0.7 to 3.9 +/- 0.8 cm (p less than 0.01), with no significant change in shortening fraction (46.1 +/- 8.0% vs 44.6 +/- 8.0%). When adjusted for body size and age there was a significant decrease in LV septal thickness (from 106 +/- 70 to 45 +/- 52% of predicted normal values, p less than 0.05) and LV posterior wall thickness (from 40 +/- 45 to 5 +/- 26% of predicted normal values p = 0.05) after verapamil. Isovolumic relaxation time decreased from 69 +/- 26 to 42 +/- 19 ms after verapamil (p less than 0.01). Systolic anterior motion of the anterior mitral leaflet disappeared in 5 of 8 patients and midsystolic closure of the aortic valve was no longer present in 4 of 8.(ABSTRACT TRUNCATED AT 250 WORDS)     

R-wave amplitude changes during exercise in adolescents with left ventricular pressure and volume overload

To determine the diagnostic value of exerciseinduced R-wave changes in adolescents with congenital heart disease, the responses of 50 adolescents without significant heart disease were compared with those of 72 patients with either a left ventricular (LV) pressure or volume overload lesion. Among the pressure overload group, 24 patients had valvular aortic stenosis (AS) and 27 had coarctation of the aorta. The volume overload group included 12 patients with mitral regurgitation (MR) and 9 with aortic regurgitation (AR). Severity of the cardiac lesion was assessed using cardiac catheterization in patients with AS, physical examination in patients with coarctation of the aorta and clinical or angiographiec criteria, or both, in patients with valvular regurgitation. The R wave was measured in 10 consecutive QRS complexes in leads II, aVF and V₅ at rest, maximal exercise and 1-minute recovery. At maximal exercise, control subjects had a mean decrease in amplitude (ΔR) of ?3.6 mm (p < 0.0001). Compared with the control group, the AS group had a similar decrease of ?3.5 mm, but the coarctation group had a ΔR of ?1.4 (p < 0.005) and the volume overload group a ΔR of ?1.1 mm (p < 0.003). Patients with AS and ischemic ST-segment changes during exercise (n = 12) had greater decreases in R-wave amplitude than did those with no ST changes (n = 12) (p < 0.04). In patients with AS and an LV end-diastolic pressure ? 12 mm Hg (n = 7), the decrease in ΔR was also greater than that in patients with LV end-diastolic pressure ≤ 12 mm Hg (n = 14) (p < 0.006). Among patients with volume overload, more severe valvular regurgitation was associated with a smaller ΔR (p < 0.03). In patients with AS an increased ΔR reflects ischemia or diminished LV compliance, or both, whereas in patients with volume overload a decrease in ΔR is an indicator of the severity of regurgitation.     

Two-dimensional echocardiographic determination of aortic and pulmonary artery sizes from infancy to adulthood in normal subjects

The aorta, right pulmonary artery and pulmonary trunk were measured from the 2-dimensional echocardiogram (2?D echo) of 110 normal subjects aged 1 day to 18 years. The vessel diameters were measured from the parasternal short-axis view, the suprasternal long-axis view and the suprasternal short-axis view. Measurements were made at end-systole and at end-diastole and in both an axial and lateral direction where possible. When analyzed with respect to body surface area (BSA), the echocardiographic measurements were linearly related to the square root of the BSA, and there was inequality of variance around the relation. To establish a range of normal values for each vessel dimension, a weighted regression analysis was used to produce estimates of the regression line and a set of tolerance intervals. The systolic vessel dimension was larger than the diastolic vessel dimension and the measurement of a vessel in an axial direction was larger than the measurement of the same vessel in a lateral direction. In general, when a vessel was measured in several views, the largest diameter was obtained using the view that imaged the vessel in cross section. These data on normal values for the echocardiographic measurement of the aorta and pulmonary arteries at different BSAs should be useful for identifying patients with abnormalities in arterial size and for the serial assessment of arterial size in children who have undergone surgical or medical therapy.     

Epicardial and endocardial activation in patients with endocardial cushion defect

Epicardial and left ventricular endocardial activation were assessed in 5 patients (aged 4 months to 9.5 years) with endocardial cushion defect (ECD) during surgical repair. Epicardial activation was recorded from 40 to 47 sites over the epicardium; left ventricular endocardial activation was measured at 3 sites immediately after institution of cardiopulmonary bypass. Compared with the reported activation sequence in normal hearts, the pattern of excitation in hearts of patients with ECD was abnormal; epicardial excitation began at the left ventricular diaphragmatic surface and spread laterally and anteriorly over the anterobasal left ventricle. It then merged with right ventricular wavefronts ending along the right ventricular anterior atrioventricular groove and outflow tract. Left ventricular endocardial activation also occurred earliest in the diaphragmatic segment of the left ventricle with later wavefronts recorded laterally and anteriorly. This study demonstrates, for the first time in human subjects, correlation between left ventricular epicardial and endocardial activation in patients with ECD. The data indicate that earliest endocardial and epicardial activation occurs at the left ventricular diaphragmatic segments of the heart, and are consistent with the known posterior and inferior displacement of the specialized atrioventricular conduction system in patients with ECD.     

Excitation of the double chamber right ventricle: Electrophysiologic and anatomic correlation

To examine the excitation of the double chamber right ventricle and the possibility that it results from a displaced, hypertrophied moderator band, seven patients with double chamber right ventricle were studied. All seven had pre- and postoperative electrocardiograms. Intraoperative right ventricular epicardial maps were obtained in three; right ventricular endocardial activation maps performed at postoperative catheterization were obtained in four. In the three patients studied at operation the breakthrough point of right ventricular epicardial activation was demonstrated in a normal inferior location well below the obstructing muscle band. Two patients with right bundle branch block after operation and two others with only right ventricular conduction delay on postoperative electrocardiogram demonstrated high normal right ventricular time with prolongation of activation in the right ventricular outflow or inflow region, or both, suggesting only peripheral injury. These data suggest that activation of the double chamber right ventricle is similar to that of the normal heart. In addition, the observed normal activation sequence militates against the hypothesis that the moderator band is the obstructing bundle.     

echocardiographic measures in 6 to 7 year old children after an 8 month exercise program

The influence of an exercise intervention program on cardiac dimensions was studied in 79 normal children (aged 6 to 7 years) in an experimental (n = 38) and control (n = 41) group. The experimental group participated in an aerobic exercise session that met four days/week for 8 months. Anthropometric measurements and M mode echocardiograms were obtained before and after the intervention program. Comparison of the data between groups revealed no significant (probability [p] > 0.05) differences in left ventricular end-diastolic dimension, shortening fraction or resting heart rate. Left ventricular posterior wall thickness exhibited a significant increase (p < 0.0256) from 3.9 to 4.7 mm in the experimental group compared with an increase from 4.3 to 4.6 mm in the control group after correcting for preintervention differences with an analysis of covariance. Likewise, left ventricular mass increased significantly (p < 0.0004) from 21.2 to 27.4 g in the experimental group compared with 23.4 to 25.8 g in the control group. These findings indicate that when compared with control subjects, young children involved in an aerobic exercise program showed progressive increases in left ventricular posterior wall thickness and left ventricular mass and no change in left ventricular end-diastolic dimension, shortening fraction or resting heart rate.     

Left ventricular aneurysms associated with intraoperative venting of the cardiac apex in children

Left ventricular (LV) apical aneurysms were observed in 16 of 50 (32%) children (average age 8 years) consecutively catheterized after surgical repair of congenital heart disease. The LV apex was vented by a sump during cardiopulmonary bypass in each. The aneurysms varied in size, but were generally small. Average dimensions were 7.5 × 6.8 mm in the anteroposterior projection and 8.9 × 5.7 mm in the left anterior oblique projection. The LV apex wall was thinner in patients with aneurysms than in age- and lesion-matched controls. All of the LV aneurysm patients were asymptomatic during average follow-up of 4 years. Nevertheless, such aneurysms are anticipated to represent a potential source of cardiovascular complications and, when possible, alternate methods for venting the left ventricle are recommended.     

Assessment of potentially salvageable myocardium during acute myocardial infarction: use of postextrasystolic potentiation

Twenty-three patients with evolving acute myocardial infarction (AMI) undergoing catheterization for thrombolytic therapy had interventional contrast ventriculography using programmed atrial stimulation. Postextrasystolic (PES) potentiation was present in 67% of infarct-related segments up to 9 hours after the onset of AMI. The presence of segmental potentiation was not related to time from onset of pain to ventriculography, initial ejection fraction, presence of collaterals, left ventricular end-diastolic pressure or the PES delay. In 18 patients reperfusion was successful using intracoronary streptokinase an average of 6.2 hours after the onset of AMI; in these patients repeat contrast ventriculography was performed an average of 11 days after AMI. Improved chronic segmental ventricular function was predicted by the presence of collaterals to the infarct-related artery at the time of acute catheterization (p = 0.02), but was best predicted by analysis of acute PES potentiation (p less than 0.0001). The predictive value of PES analysis was highest in segments without collaterals. Thus, atrial stimulation is safe during AMI and analysis of segmental ventricular function shows potentially viable myocardium up to 9 hours after the onset of AMI. In addition, analysis of PES segmental function can predict chronic function if reperfusion is successful, especially in segments without collaterals. PES ventriculographic analysis may allow prospective determination of which patients during AMI are most likely to benefit from acute thrombolytic therapy.