Dietary calcium, calcium supplementation, and blood pressure in African American adolescents.

BACKGROUND: Intake of calcium from the diet is inversely associated with blood pressure in observational studies and animal models but randomized trials in humans have found only small effects of calcium supplementation on blood pressure. A blood pressure-lowering effect of calcium supplementation may thus be restricted to persons with a low intake of calcium from the diet and specific genetic or other characteristics. OBJECTIVE: A randomized trial was conducted to assess the effect of calcium supplementation on blood pressure in African American adolescents. Rapid growth during adolescence may increase calcium requirements, and avoidance of milk and milk products by some African Americans can result in low intake of calcium. DESIGN: One hundred sixteen adolescents (65 girls, 51 boys; mean age: 15.8 y) were given calcium (1.5 g/d) or placebo for 8 wk in a randomized, double-blind, crossover design. Blood pressure was measured after 2, 4, and 8 wk. Dietary calcium was determined with a validated food-frequency questionnaire. RESULTS: The net effect (+/-SE) of calcium supplementation on diastolic blood pressure was a reduction of 1.9 +/- 1.1 mm Hg (P = 0.04, one-tailed t test). Blood pressure reduction was greater in adolescents with lower intake of calcium from the diet (P = 0.003, one-tailed t test for interaction): -4.9 +/- 1.6, -2.3 +/- 1.6, and 1.4 +/- 1.8 mm Hg for change in the lower (0.024-0.067 g Ca/MJ), middle (0.069-0.091 g Ca/MJ), and upper (0.093-0.217 g Ca/MJ) tertiles, respectively. No main effect on systolic blood pressure was detected. CONCLUSION: These findings suggest that calcium supplementation may lower diastolic blood pressure in African American adolescents with low dietary intakes of calcium.

Diagnosis and management of hypertension in childhood.

Blood pressure measurements should be taken at intervals on all children. At the very least, blood pressure measurements should be recorded on school and hospital admission. Once obtained, the pressure should be compared to established normals. If the pressure is repeatedly high, hypertension may be diagnosed and a cause sought. Unfortunately, most hypertension is usually mild in childhood, treatment programs should be initiated using nonpharmacologic measures. If needed a number of effective antihypertensive medications are available. The step-care approach presented in this article may be helpful in guiding the pediatric practitioner in this therapy.

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.

Blood pressure in youth from four ethnic groups: the Pasadena Prevention Project.

To explore the racial differences in blood pressure levels in American youth, and to extend current data to include youth of Asian, black, Hispanic, and non-Hispanic white descent, we recorded blood pressures among ninth graders during the spring of the years 1985 to 1989 in a suburb of Los Angeles. Trained observers, following a standardized protocol, obtained blood pressure measurements from 4577 students (39% black, 30% Hispanic, 21% white, 10% Asian; 50% female) with a mean age of 15 years. With the use of age- and sex-specific 90th percentiles reported in 1987 by the Second Task Force on Blood Pressure Control in Children to define elevated blood pressure, the prevalence of elevated systolic blood pressure (SBP) was 8.1% (diastolic blood pressure (DBP), 9.3%) among female subjects and 16.0% (DBP, 18.5%) among male subjects. Comparisons of the prevalence of elevated blood pressure among ethnic-racial groups within sexes were statistically significant only for Asian girls (SBP, 13.1%; DBP, 14.0%) relative to other female subjects (SBP, 7.6%, p < 0.005; DBP, 8.8%, p < 0.01); these differences persisted after adjustment for body height and body mass index. A similar trend for Asian boys was apparent only for DBP (23.0% vs 18.0%, p = 0.065). Results for group means were comparable: average SBP and DBP were higher for Asian girls than for other ethnic groups. In addition, boys in this sample may have higher blood pressure than boys from other areas of the country. These results suggest that Asians in California may be at greater risk of having early development of hypertension.

Cardiac pacemaker in high spinal cord injury.

Bradycardia followed by cardiac arrest is well documented as a complication of acute injury to the cervical spinal cord. This life-threatening bradycardia is attributed to an imbalance in the autonomic nervous system resulting from dissociation of the parasympathetic from the sympathetic responses during the stage of spinal shock. A patient with a C2 complete quadriplegia secondary to birth trauma who experienced symptomatic bradycardia, continuing for 21 months after injury despite intensive medical management, is reported. Clinical improvement followed insertion of a cardiac pacemaker. Possible etiologies for the continuation of abnormal bradycardia episodes after the resolution of spinal shock are discussed. Cardiac pacemaker implantation is advocated for patients with high cervical spinal cord injuries and continuing symptomatic bradycardia not responding to medical measures.

Stress testing for comparison of synthetic patch aortoplasty with resection and end to end anastomosis for repair of coarctation in childhood.

Excellent clinical results have been achieved by both resection with end to end anastomosis and synthetic patch aortoplasty for the repair of coarctation of the aorta in older children. Increasing experience with exercise stress testing in the postoperative evaluation of patients with coarctation has allowed the discovery of less obvious differences between the two procedures. To evaluate these differences further, the stress tests of 50 postoperative patients who underwent coarctation repair were reviewed: 26 patients with end to end anastomosis and 24 with synthetic patch aortoplasty. Twenty normal control subjects were similarly exercised. Systolic blood pressure in the arm and leg was evaluated before and after the test. Heart rate, electrocardiogram and arm blood pressure were monitored during the test. The mean arm systolic blood pressure was higher at all points of measurement in the patients who underwent repair by end to end anastomosis than in the group who underwent patch aortoplasty. These systolic pressure differences reached statistical significance only for standing arm blood pressure before exercise (p less than 0.05) and for supine arm systolic blood pressure immediately after exercise (p less than 0.01). There was no difference in arm-leg pressure gradient between the two study groups before exercise; however, after exercise the group with end to end anastomosis had significantly higher arm-leg pressure gradients (p less than 0.001). Significant differences between the two types of repair not apparent at rest were found immediately after exercise. The long-term prognostic importance of an exercise-induced arm-leg blood pressure gradient remains to be determined. However, exercise stress testing is sensitive in demonstrating these differences.

Growth of the aorta after prosthetic patch aortoplasty for coarctation in infants.

We have shown that patch aortoplasty relieves the aortic pressure gradient substantially better than resection with end-to-end anastomosis in infants with coarctation of the aorta. Growth of the intact posterior wall of the unresected coarctation after aortoplasty, however, has not yet been demonstrated to occur. We studied 21 infants less than 2 years of age who underwent prosthetic patch repair of coarctation after 1975. Associated lesions were present in 16 patients, and 12 had a concomitant procedure. Two patients died in the hospital, and 4 died later, all of causes unrelated to the coarctation repair. Systolic blood pressure in the right arm declined from 140 +/- 41 mm Hg (mean +/- standard deviation) preoperatively to 101 +/- 19 mm Hg postoperatively in the whole group and to 95 +/- 12 in 10 patients followed for more than 3 years. The right arm-left leg systolic pressure gradient declined from 66 +/- 22 mm Hg to 5 +/- 14 in all patients and to 4 +/- 13 in the group followed more than 3 years. Hypoplastic transverse arch was seen in all but 2 patients. Its relative diameter increased in 6 of 9 patients who underwent catheterization postoperatively and increased more than 50% in 3 patients. Two patients have evidence of narrowing of the aorta at the patch, but both have normal blood pressure in the right arm. In the patient with longest follow-up, an 8-month-old infant seen 8 years after operation, angiograms show the diameter of the aorta at the coarctation to be greater than that at the transverse arch and at the descending aorta.(ABSTRACT TRUNCATED AT 250 WORDS)

Cardiac valve prostheses in children without anticoagulation.

We have used the St. Jude Medical cardiac valve prosthesis without postoperative anticoagulation in 34 children undergoing valve replacement since March, 1979. The 19 boys and 15 girls ranged in age from 9 months to 21 years. The valve replaced was mitral in 12 patients, aortic in 14, pulmonary in three, and both mitral and aortic in two. One patient had implantation of a St. Jude Medical valve in a pulmonary conduit, and a left-sided tricuspid valve was replaced in two children. There were three operative deaths, all in infants with complex disease. One patient died suddenly at home 5 weeks after valve replacement, probably of ventricular arrhythmia. During follow-up of 1 to 50 months, comprising 646 patient months, no thromboembolic complications have been observed. Although use of the St. Jude Medical prosthesis without anticoagulation is still investigational, our preliminary data suggest that the risk of thromboembolism in unanticoagulated children with this valve is not greater than that in anticoagulated adults. The results justify continuing investigation of the St. Jude Medical prosthesis in children without postoperative anticoagulation.

Juvenile hypertension: highlights of a workshop.

The workshop was successful in achieving its two major goals: (1) the scientific updating of research issues in pediatric blood pressure determinants and in pediatric hypertension, and (2) the delineation of future research objectives. These objectives are itemized at the end of the workshop proceedings and, in brief, center around the need for better definitions of normal and abnormal blood pressures in youth, the identification of variables in childhood capable of indicating which children are at risk for developing hypertension as adults, and finally, a thoughtful list of additional research issues germane to the explanation of primary and secondary forms of hypertension.

Discrete subaortic stenosis.

From 1971-1981, 18 patients with discrete subaortic stenosis were treated surgically at the Medical University of South Carolina. Echocardiography was diagnostic in 10 of 11 patients in whom it was used. Preoperative cardiac catheterization was performed in all patients. The preoperative left ventricular outflow systolic pressure gradient was 82.0 +/- 27.2 mmHg (mean +/- SD) (range 30-145). In 16 (88.8%) patients excision of the subaortic membrane was complete, and relief of left ventricular outflow obstruction was good. The excision was incomplete in 2 patients; one required reoperation for residual gradient and developed complete heart block, and the other had a residual gradient of 60 mmHg and was in New York Heart Association functional class II when lost to follow-up. These data suggest that complete excision of the discrete subaortic stenosis is important to achieve good relief of left ventricular outflow obstruction.

Inflow occlusion for semilunar valve stenosis.

Twenty-nine patients have had valvotomy with inflow occlusion since 1975 at our institution: 7 for aortic stenosis and 22 for pulmonary stenosis. All patients with aortic stenosis and 11 with pulmonary stenosis were neonates. Six patients died, 3 with aortic stenosis and 3 with pulmonary stenosis. All of them were less than 2 days old. Two newborns with critical pulmonary stenosis required reoperation with an outflow patch at age 22 and 25 months. To determine morbidity and expense of inflow occlusion versus cardiopulmonary bypass for patients with pulmonary stenosis, we compared the 11 patients who were not infants and who had inflow occlusion (age range, 3.5 to 26.8 years) with 10 patients who were operated on concurrently and who required bypass to correct associated minor intracardiac lesions (age range, 2.6 to 26.4 years). Significant differences (p less than 0.01) were as follows (inflow occlusion versus bypass): operating room time, 2.0 +/- 0.4 versus 3.6 +/- 0.8 hours (mean +/- standard deviation); blood utilized, 0.3 +/- 0.5 versus 1.7 +/- 1.7 units; and total expense, $4,600 +/- 800 versus $7,000 +/- 1,600. Thus, inflow occlusion is safe in patients more than 2 days old, with early and late results similar to bypass, and is an attractive alternative for patients with isolated pulmonary valvular stenosis and for newborns with aortic stenosis.

Repair of left atrial abnormalities in children by the superior approach.

We have used the superior approach through the dome of the left atrium to repair cardiac lesions in the left atrium in 15 children ranging from 3 months to 17 years old. The single hospital death occurred in a 16-month-old infant with levo (L) transposition of the great arteries, Ebstein's malformation of the left atrioventricular valve, and ventricular septal defect. Exposure of the intraatrial structures was excellent, injury to adjacent cardiac structures did not occur, and hemorrhage from the left atrial suture line was not a problem. Though a few transient arrhythmias were seen, all survivors are in sinus rhythm without evidence of sick sinus syndrome, except 1 patient in whom atrial flutter associated with cardiomyopathy developed 1 year after operation. The excellent surgical exposure obtained of the interior of the left atrium and the absence of important complications related to the incision cause us to recommend this approach in children.

Maintaining patency of the ductus-arteriosus for palliation of cyanotic congenital cardiac malformations. The use of prostaglandin E1 and formaldehyde infiltration of the ductal wall.

We have used two methods to maintain ductal ppatency in 13 newborns during surgery for congenital cardiac malformations: prostaglandin E1 (PGE1) infusion for the short-term and formaldehyde infiltration of the ductus arteriosuos (FID) for the longer term. PGE1 increased the arterial oxygen saturation, leading to stable intraoperative hemodynamics in the six infants in whom it was used. FID was used in all 13 patients. Four of these patients died in the hospital, all with the ductus open. Of the nine early survivors, all required an additional shunt procedure. The five long-term survivors had the second palliative operation immediately, three hours, three days, two and one-half months, and four and one-half months after FID. We continue to use PGE1 to maintain ductal atency through operation, but use aortopulmonary anastomosis in the newborn period rather than FID.

Blood pressure, heart rate, pressure-rate product and electrocardiographic changes in healthy children during treadmill exercise.

Heart rate, systolic and diastolic blood pressure, rate-pressure product and electrocardiographic changes were measured in 288 healthy children during treadmill exercise. A constant speed (3.5 miles/hour) protocol was used to facilitate the measurements of physiologic data during exercise. Because responses to exercise vary with size, the children were separated into four groups according to body surface area. Comparisons were also made between male and female and between black and white children. The values for heart rate and systolic pressure showed excellent reproducibility in repeated tests. These data establish for clinical use reference values for children during treadmill exercise.