Use of intravenous amiodarone for postoperative junctional ectopic tachycardia in children.

To assess the efficacy and safety of intravenous (IV) amiodarone for the treatment of postoperative junctional ectopic tachycardia (JET) in children, we retrospectively reviewed 11 patients treated with IV amiodarone for JET between 1/92 and 2/00. Data included heart rate and hemodynamics pre- and post-amiodarone, drug dosage, duration of therapy, and effect. Success was defined as reversion to sinus rhythm or slowing to a hemodynamically stable rate. The mean heart rate prior to amiodarone was 203 bpm, and the mean systolic blood pressure was 64 mmHg. Mean IV amiodarone loading dose was 8.2 +/- 4.0 mg/kg, followed by an infusion in 7 patients at a dose of 12.9 +/- 3.9 mg/kg/day for a duration of 74.3 +/- 46.9 hours. At 1 hour post-load, mean heart rate was 147 bpm and mean systolic blood pressure was 88 mmHg for the group. Three patients were in sinus rhythm, 4 in intermittent sinus rhythm with accelerated junctional rhythm, and 4 patients solely accelerated junctional rhythm. Control of JET persisted in 9 patients. Of the two patients requiring additional treatment, both had received a 5 mg/kg load and neither was on an infusion. Five patients were paced at some point following amiodarone: four to improve hemodynamics and one for late sinus bradycardia. Side effects included hypotension with loading (1) and late sinus bradycardia (1). One patient was discharged on oral amiodarone. Intravenous amiodarone given in doses of 10 mg/kg in two 5 mg/kg increments, followed by an infusion of 10-15 mg/kg/day for 48-72 hours, appears to be safe and effective for postoperative JET in patients who fail conventional therapy or who are hemodynamically unstable. Long-term oral therapy is usually not necessary.

Usefulness of exercise stress testing for prediction of blood pressure trends.

The purpose of this study was to determine whether values of blood pressure during exercise help predict which adolescents are prone to maintain high blood pressure. Dynamic and isometric exercise stress tests were performed on 131 adolescents who had had systolic or diastolic pressures greater than the 95th percentile on three examinations the previous year. Follow-up blood pressures were measured 1 year after the stress testing, and outcomes were classified on the basis of the blood pressure status that year. Stepwise regression analysis was used to examine the association between earlier blood pressures and exercise pressures with outcome pressures. In both male and female adolescents, the average resting systolic pressure on the earlier survey was the best predictor of systolic pressure 2 years later. Blood pressures and heart rates during dynamic and isometric exercise did not significantly contribute to the models' prediction of future systolic or diastolic pressures. The data suggest that exercise stress testing is not a valid method for predicting youths whose blood pressures will remain elevated over the next 1 to 2 years.

Body size, composition, and fitness in adolescents with elevated blood pressures.

Increased body size is often found in children with elevated blood pressures, but it is not clear whether this is a result of obesity or early maturity. Similarly, levels of activity and fitness have marked effects on blood pressure and body composition. To study these interrelated factors, we measured height, weight, and body composition (skinfold thickness and total body water) as well as heart rate, blood pressure, and oxygen consumption at rest and during exercise in 192 ninth grade boys and girls, 102 with persistently elevated blood pressures at or above the 95th percentile and 90 matched controls with blood pressures below the 50th percentile for the entire population of 10,641 Dallas County ninth graders tested. Differences in resting blood pressures also were present during maximal exercise and recovery periods. Boys with persistently elevated blood pressures were characterized by increased supine and recovery heart rates, normal fitness, excess size for age in the absence of obesity, and early maturation. Girls with persistently elevated blood pressures had increased heart rates, decreased fitness, and obesity.

Validity of mass blood pressure screening in children.

The validity of a mass blood pressure screening program carried out on Dallas high school students who were followed for at least 3 years is reported. Blood pressure results on initial screening in the tenth grade were related to outcome blood pressure status. The frequency of initial blood pressure elevation (systolic and/or diastolic pressure above the 95th percentile) was 10%, whereas the prevalence of sustained elevation in the tenth grade was less than 2%. The initial screening correctly identified 72% of those who had sustained elevations on all three tenth grade examinations (sensitivity), and correctly identified 91% of those who did not have sustained elevations (specificity). However, the predictive value of an initial positive screening result was low, at only 17% (152/900). The high proportion of false-positive results represents a significant cost to any blood pressure screening program, both in economic terms and in its potential for creating anxiety among families with children having only transiently elevated blood pressure. Because the costs are high and the yield from mass screening of children low, case finding of childhood hypertension should remain the responsibility of the physician who sees children in the clinical setting.

Left ventricular hypertrophy in adolescents with elevated blood pressure: assessment by chest roentgenography, electrocardiography, and echocardiography.

The purpose of this study was to assess the prevalence of left ventricular hypertrophy in adolescents with persistently elevated blood pressures. Chest roentgenograms, electrocardiograms, and echocardiograms were performed on 50 adolescents with elevated blood pressure and 50 matched normotensive control subjects. No subject in either group demonstrated cardiomegaly on x-ray. Interpretation of the electrocardiograms indicated that similar numbers of both hypertensive (7/50) and control subjects (8/50) had ECG evidence of left ventricular hypertrophy. The echocardiograms showed that the mean left ventricular wall thickness (LVWT) in the hypertensive adolescents was 7.8 mm +/- 0.1 (SE), compared with 6.5 +/- 0.1 in the control subjects (P less than .001). When the measurements were indexed to body surface area, the difference remained highly significant. Indexed left ventricular mass (LVM)/body surface area (BSA) was also significantly greater (P less than .001) in the hypertensive (84.2 gm/sq m +/- 2.1) than in the control subjects (72.0 +/- 2.1). Using data from the normotensive control subjects, we defined the 95th percentile for both LVWT/BSA and LVM/BSA. Among hypertensive adolescents, 9/50 had LVWT/BSA and 8/50 had LVM/BSA above this level. For control subjects, only 1/50 had elevated LVWT/BSA values and 2/50 elevated LVM/BSA values. This study demonstrates that hypertensive adolescents have an increased prevalence of left ventricular hypertrophy and that echocardiography is the most useful noninvasive method to detect these changes.

Effects of clonidine on 24-hour hormonal secretory patterns, cardiovascular hemodynamics, and central nervous function in hypertensive adolescents.

To assess the potential of antihypertensive drugs for interference with somatic growth and sexual development in hypertensive children, the effect of clonidine therapy on various endocrine, cardiovascular, and neuromuscular functions has been examined in five male adolescents with idiopathic hypertension. In studies done before and at the end of 4 weeks of twice-daily clonidine therapy, in an average daily dose of 0.31 mg, no significant effects were noted in the secretory patterns of growth hormone, luteinizing hormone, follicle-stimulating hormone, prolactin, cortisol, aldosterone, or testosterone, measured in blood obtained every 20 minutes for 24 hours. In blood obtained while the patients were supine and then erect, plasma renin activity and norepinephrine levels were significantly lowered after clonidine therapy. Cardiovascular responses to dynamic exercise were little altered beyond a 17% decrease in maximal oxygen consumption. The performance of fine motor skills was minimally altered. These data provide preliminary evidence that clonidine, an antihypertensive drug that affects the adrenergic nervous system, may not interfere with normal growth and maturation in adolescent males.

Response of hypertensive adolescents to dynamic and isometric exercise stress.

Isometric handgrip and dynamic exercise stress tests were performed on 109 hypertensive and 74 normotensive subjects 14 to 17 years old. The hypertensive subjects had resting systolic or diastolic pressures persistently above the 95th percentile on four consecutive examinations. Blood pressures and ECGs were recorded during isometric handgrip (25% maximum effort for four minutes) and bicycle ergometry until the subject was exhausted. The hypertensive subjects increased systolic pressure by an average 16 mm Hg with isometric exercise and 53 mm Hg with dynamic exercise. Control subjects had similar pressure changes, averaging 18 and 54 mm Hg, respectively. During isometric handgrip stress, diastolic pressures increased 12 mm Hg in hypertensive subjects and 18 mm Hg in control subjects. Only two hypertensive adolescents developed systolic pressures exceeding 200 mm Hg during dynamic exercise stress, and none developed systolic pressures above 200 mm Hg during isometric exercise stress. None of the normotensive or hypertensive subjects developed cardiac arrhythmias and the prevalence of ST segment depression during maximal stress was less than 2% in both groups. Therefore, in adolescents with mild to moderate hypertension the risk of developing significant ECG or hemodynamic abnormalities during mild isometric or heavy dynamic exercise is small. We believe the decision to restrict physical activity of an adolescent with elevated pressures should be based on the development of abnormal ST segment depression, cardiac arrhythmias, or excessive blood pressures at the time of exercise stress testing.

Fatal Haemophilus influenzae endocarditis diagnosed by echocardiography in an infant.

A 1-year-old boy was admitted to the hospital with Haemophilus influenzae meningitis. On the second hospital day a heart murmur heard on admission seemed louder. No signs of congestive heart failure were present. An echocardiogram demonstrated a persistent echo-dense mass behind the anterior leaflet of the mitral valve. A presumptive diagnosis of endocarditis was made. After ten days of antibiotic treatment the child was considerably improved. Treatment was continued for endocarditis. Over the next several days the infant's condition deteriorated. On the 16th hospital day he died. Autopsy examination showed a large vegetation attached to the posterior mitral valve leaflet. Bacterial endocarditis caused by H influenzae is uncommon at any age and rare in children. Echocardiography provided a definitive diagnosis early in the hospital course of this patient.

The frequency of pericardial effusions in bacterial meningitis.

Because of our experience with four cases of purulent pericarditis complicating bacterial meningitis during a 13-month period, we performed a prospective study to determine the frequency of this complication. Echocardiograms were done on 100 patients with bacterial meningitis. Small or moderate pericardial effusions were detected in 19 patients, but none had symptoms or signs related to the effusion. Pericardiocentesis was done in one infant; all the other effusions resolved spontaneously. Patients with effusion were significantly younger than those without this complication, but no other significant risk factors were identified. A literature survey indicated that symptomatic pericarditis occurs in fewer than 1% of patients with meningitis. Conversely, in series of cases of purulent pericarditis, associated meningitis was reported in 12% of patients. We concluded that pericardial infection is common in patients with meningitis but that it is usually of no clinical significance and resolves with antibiotic therapy.

Cardiovascular response to isometric exercise in normal adolescents.

The purpose of this study was to document the cardiovascular response to submaximal isometric handgrip (IHG) exercise in 32 normal adolescents. Left ventricular (LV) dimensions and systolic time intervals were recorded using echocardiography; blood pressure was measured by sphygmomanometry both at rest and during IHG exercise at 25% maximum contraction. This level of isometric exercise produced significant (p less than 0.001) increases in mean heart rate, systolic, diastolic and mean blood pressures. Despite this response LV diastolic and systolic dimensions remained unchanged during exercise; hence, stroke volume remained constant. Cardiac index increased by 22% (p less than 0.001) due to the increase in heart rate. Systemic vascular resistance did not change significantly. LV ejection indices, including shortening fraction, mean Vcf and systolic time intervals also remained unchanged, except for an increase in LV ejection time index (p less than 0.025). These data indicate that the cardiovascular response to submaximal isometric exercise in normal adolescents is similar to that reported in adults. This study demonstrates that sustained isometric stress testing in adolescents is safe and provides normal hemodynamic values.

Hypertension screening in schools: results of the Dallas study.

The purpose of this study was to determine the prevalence of persistent blood pressure elevations in an eighth-grade population composed of three ethnic groups, and to determine the feasibility of using school health facilities for hypertension screening. Blood pressure was recorded in 10,641 subjects (90% of the total eighth-grade population) in the Dallas Independent School District. Blacks made up 46% of the population; non-Latin whites, 40.1%; and Latin-Americans, 13.9%. On the first blood pressure screening, 8.9% had systolic or diastolic pressures or both at or above the 95th percentile. Of those whose blood pressures were elevated on the first examination, 98.3% were reexamined. After the third examination, 1.2% continued to have systolic hypertension, and 0.37% diastolic hypertension. No student had diastolic pressure above 90 mm Hg on all three examinations. The prevalence of persistent hypertension was similar for the three ethnic groups. Analysis of variation in blood pressure measurements revealed that the school nurses introduced a relatively small increase in variability. These data indicate that although school screening initially identifies large numbers of students as having inconstant pressure elevations, subsequent follow-up examinations show that less than 2% have persistent hypertension.

Echocardiography of premature infants with pulmonary disease: a noninvasive method for detecting large ductal left-to-right shunts.

Echocardiography was used to evaluate premature infants with large patent ductus arteriosus (PDA) shunts and proved lung disease. A PDA producing large left-to-right shunting also causes left atrial enlargement. Since the left atrial diameter (LAD), measured by ultrasound, normally varies with body size, its value was compared to that of the aortic root diameter (AO) to adjust for body size variations. In those infants with pulmonary disease but no significant PDA, the range of LAD/AO ratios was similar to that of the control group. In patients with a proved large PDA the ratios were significantly higher. The ultrasound ratio returned to normal in all cases following surgical ligation of the PDA.

Hepatic hemangiomatosis. Successful management by hepatic artery ligation.

Successful management of severe congestive heart failure secondary to a hepatic hemangioma was accomplished by ligation of the hepatic artery in a 2-month-old infant. In the two years since the operation, follow-up observations including liver biopsy and hepatic angiography have indicated complete regression of the tumor. This report provides reassurance that this procedure is effective in the prompt control of severe heart failure, as well as in safely providing time for the spontaneous regression of the vascular tumor.

Staphylococcal septicemia: successful treatment of complications in a child.

A previously healthy 5-year-old girl developed staphylococcal septicemia. Initially, cardiovascular failure with mitral insufficiency and purulent pericarditis dominated the clinical picture. Peripheral thromboembolic phenomena, meningitis, osteomyelitis, and persistent septicemia were subsequently encountered during antimicrobial and surgical therapy. Although staphylococcal septicemia is a potentially lethal disorder, anticipation of its natural course and its possible complications should lead to more successful management.