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Biomedical subjects

B S Alpert

Publications and source records attributed to B S Alpert.

At least 37 records · Page 2Linked to original sources
PubMed1995

Pulmonary/systemic flow ratio in children after cavopulmonary anastomosis.

OBJECTIVES: This study attempted to provide a formula for calculation of the pulmonary/systemic flow ratio in children after bidirectional cavopulmonary anastomosis. BACKGROUND: With the bidirectional cavopulmonary anastomosis, only the superior vena cava blood is oxygenated by the lungs. The inferior vena cava flow recirculates into the systemic circulation. The ratio of these flows will determine systemic arterial saturation. METHODS: According to the Fick principle, 1) Systemic cardiac output (liters/min) = Pulmonary venous flow + Inferior vena cava flow; 2) Systemic blood oxygen transport (ml/min) = Pulmonary venous blood oxygen transport + Inferior vena cava blood oxygen transport. By substituting the first equation into the second, Pulmonary/systemic flow ratio = (Systemic saturation - Inferior vena cava saturation)/(Pulmonary venous saturation - Inferior vena cava saturation). RESULTS: We applied the third formula to data obtained from 34 catheterizations in 29 patients after bidirectional cavopulmonary anastomosis. Mean [+/- SD] age at operation was 1.70 +/- 1.43 years, and mean age at catheterization was 2.95 +/- 1.65 years. The pulmonary/systemic flow ratio calculated for all 29 patients was 0.58 +/- 0.09. Of 17 patients with aortography, 10 had systemic to pulmonary collateral vessels. Patients with collateral vessels had a significantly higher pulmonary/systemic flow ratio (0.61 +/- 0.07 vs. 0.53 +/- 0.07, respectively, p < 0.02) and systemic saturation (88 +/- 4% vs. 82 +/- 4%, respectively, p < 0.002) than those without collateral vessels. The pulmonary/systemic flow ratio in those patients with no collateral vessels was similar to the previously reported echocardiographically derived superior vena cava/systemic flow ratio in normal children. CONCLUSIONS: The pulmonary/systemic flow ratio after bidirectional cavopulmonary anastomosis can be calculated. Pulmonary blood flow in these patients determines systemic saturation and accounts for the majority of venous return in young children.

Child, Preschool↗
PubMed1995

Absorption pharmacokinetics of atenolol in patients with the Marfan syndrome.

The negative inotropic and chronotropic effects of beta-blocker therapy have been reported to reduce morbidity and mortality in patients with Marfan syndrome; however, little is known about the pharmacokinetics of atenolol after oral administration of multiple doses to patients with the Marfan syndrome. We studied the pharmacokinetics of atenolol in 13 such patients aged 18.7 +/- 2.9 years who were receiving 1.78 +/- 0.58 mg/kg/day (70.1 +/- 20.3 mg/m2/day) of atenolol for 6 weeks or longer. Mean +/- SD percentage change in baseline heart rate after the administration of atenolol was -18.03 +/- 16.59% and mean +/- SD percentage change in exercise heart rate after atenolol was -33.22 +/- 14.75% (P < .01). Six to 8 atenolol serum concentrations were collected in each patient during a 12-hour dosing interval and were determined by high-performance liquid chromatography with ultraviolet detection. Serum atenolol concentrations at 0 (123 +/- 70 micrograms/L) and 12 (116 +/- 66 micrograms/L) hours were within 20% of each other and were thus assumed to be at steady-state. A one-compartment, steady-state pharmacokinetic model with first-order absorption and elimination was fitted to the concentration-time data for each patient using nonlinear regression. Maximal concentration was 343 +/- 120 micrograms/L, and the mean half-life was 4.72 hours.(ABSTRACT TRUNCATED AT 250 WORDS)

Absorption↗
PubMed1995

The fate of homograft conduits in children with congenital heart disease: an angiographic study.

The use of homograft conduits in the repair of congenital heart disease is widely accepted. We reviewed the catheterization and angiographic data from 20 patients with homograft conduits. All conduits were to the pulmonary arteries. The age at operation was 4.7 +/- 5.6 years (mean +/- standard deviation) and at follow-up catheterization, 7.8 +/- 6.7 years. At implantation, conduit cross-sectional area and Z value were 219 +/- 96 mm2 and 3.5 +/- 1.8, respectively. At subsequent catheterization, the conduit diameters were measured in two projections at the shaft, annulus, valve opening, and insertion into the pulmonary artery. The transconduit gradient was 47 +/- 26 mm Hg. The cross-sectional areas were 149 +/- 56 mm2 at the shaft, 151 +/- 92 mm2 at the annulus, 108 +/- 116 mm2 at the valve opening, and 127 +/- 84 mm2 at the pulmonary artery insertion. The Z values were -0.9 +/- 2.5, -0.9 +/- 2.8, -3.8 +/- 4.0, and -2.0 +/- 3.4, respectively. The cross-sectional areas and the Z values at the levels of measurement were significantly smaller than the corresponding values at implantation. The change in cross-sectional areas and Z values exceeded what would be expected from growth alone. These data indicate that there is a decrease, with time, in the functional lumen of homograft conduits, and this may have implications for follow-up strategy after implantation.

Adolescent↗
PubMed1995

Patent ductus arteriosus ligation: are we doing better?

Limitation on health care resource use is stimulating critical evaluation of previous preoperative standards. We retrospectively reviewed the clinical and hospital financial records of all children admitted for patent ductus arteriosus ligation from July 1984 to April 1994 for age, perioperative length of stay, readmissions for postoperative surgical problem, and hospital charges adjusted to 1994 dollars. Patients with an isolated patent ductus arteriosus, greater than 3 months of age, without preoperative or postoperative complications were included in this study and stratified into two groups based on date of operation. Group I had operation before January 1, 1991, and group II had operation on or after January 1, 1991. Comparison of these two groups revealed a significant difference in perioperative length of stay (group I, 3.9 +/- 1.2 days [mean +/- standard deviation]; group II, 2.7 +/- 0.9 days; p < 0.0001) and in hospital charges (group I, $8,700 +/- $2,100; group II, $6,600 +/- $1,000; p < 0.0001). These data support the premise that children older than 3 months undergoing elective ligation of a patent ductus arteriosus have been treated with improved efficiency and less charge without an increase in postdischarge morbidity. Health care policy decisions have forced us to evaluate the standards of perioperative care more critically.

Adolescent↗
PubMed1995

American National Standard for nonautomated sphygmomanometers. Summary report.

The Association for the Advancement of Medical Instrumentation develops voluntary standards for medical devices so that manufacturers might provide information on their product and basic safety and performance criteria that should be considered in qualifying the instrument for clinical use. American National Standards are generated through a consensus process by committees of experts in research, development, and design from user, industry, and government communities. Draft standards are made available for public review and become American National Standards after review by the American National Standards Institute. This report is a summary of the American National Standard that establishes both the safety and performance requirements of pneumatic and other nonautomated sphygmomanometers (especially mercury gravity and aneroid sphygmomanometers) used in the indirect measurement of blood pressure. This standard was developed by a consensus panel from academia, industry, and government; it updates the previous standard approved by the American National Standards Institute in 1986. This summary report does not cover all of the provisions of the revised 1994 American National Standard, thus users, researchers, and instrument designers should refer to the standard for detailed requirements.

Blood Pressure Determination↗
PubMed1995

Genetic influences on ambulatory blood pressure patterns. The Medical College of Virginia Twin Study.

The genetic influence of ambulatory blood pressure and heart rate was examined in 38 pairs of monozygotic twins, 17 pairs of same-sex dizygotic twins, and 11 pairs of opposite-sex dizygotic twins, all aged 15 or 17 years. The data were analyzed taking into consideration that the response was multivariate (24-h values) instead of the usual univariate response. The results demonstrated the heritability of ambulatory blood pressure and heart rate. This was true regardless of whether the estimate of heritability involved monozygotic twin pairs compared to same-sex dizygotic twin pairs only, or all dizygotic twin pairs. The time-related intraclass correlation coefficient within each twin classification indicated that the patterns of response within twin pairs correlated more for monozygotic twin pairs than within twin pairs for either set of dizygotic twin pairs. In addition, although the opposite-sex dizygotic twin pairs may have different mean levels of response, they exhibit a similarity of patterns of response akin to that seen within same-sex dizygotic twin pairs.

Adolescent↗
PubMed1995

Gender and ethnicity in children's cardiovascular reactivity: 7 years of study.

A total of 295 children (127 White boys, 15 Black boys, 133 White girls, and 20 Black girls) participated in reactivity examinations in 1987 (all were in 3rd grade; age, M = 9.1 years), 1988, 1989, 1991, 1992 and 1993 (all were in 9th grade; age, M = 15.1 years). An analysis of residualized reactivity change values indicated consistent and significant ethnicity effects (Blacks greater than Whites) for systolic and diastolic blood pressure and for heart rate. Gender effects were also apparent for both systolic and diastolic blood pressure (boys greater than girls). These data suggest that the transition from childhood to adolescence is associated with a significant pattern of ethnic differences in reactivity, although the association of this pattern with the development of cardiovascular risk and disease remains to be ascertained.

Adolescent↗
PubMed1994

Systolic blood pressure response to exercise in black and white preadolescent and early adolescent boys.

OBJECTIVE: To investigate differences in the response of systolic blood pressure (SBP) to exercise in black and white boys while controlling for the possible confounding effects of relative body weight, body surface area, physical work capacity index, preexercise SBP, and average power output. DESIGN: Comparative and correlational. PARTICIPANTS: Eighty-seven black and 52 white boys between the ages of 5 and 16 years. Participants were recruited from day camps, community centers, and summer recreation programs in and near Augusta, Ga. INTERVENTIONS: None. MEASUREMENTS/MAIN OUTCOMES: The slope of the SBP response to exercise was not significantly different between groups. Analysis of covariance revealed race, age, relative body weight, body surface area, preexercise SBP, and average power output to be significant univariate predictors of SBP at each power output. With multiple regression analyses, the effect of race was removed, and only preexercise SBP and average power output were found to be significant predictors of exercise SBP. CONCLUSION: There were no significant differences between black and white boys in the SBP response to exercise after controlling for the effects of preexercise SBP and average power output.

Adolescent↗
PubMed1994

When to measure resting values in studies of children's cardiovascular reactivity.

Investigations suggesting that the order of obtaining resting and cardiovascular reactivity measurements moderates values have provided inconsistent results and have not analyzed data from children; the generalizability of results is uncertain. In this investigation, all children enrolled in the eighth-grade classrooms of the public schools of an entire county (n = 451) participated in standardized reactivity assessments. The order of resting and reactivity measurements was randomized by examination day (a total of 19 days). Analyses indicated that all comparisons of order effects on mean resting blood pressure and heart rate, as well as reactivity (both change from resting and absolute values and both mean and maximal values), were nonsignificant. Results indicate that measurement order is not always a necessary consideration in studies of reactivity; the conditions under which measurement order is a consideration requires clarification.

Adolescent↗
PubMed1994

Ambulatory blood pressure and renal function in healthy children and adolescents.

Our previous studies using noninvasive ambulatory blood pressure (ABP) monitoring demonstrated racial differences in the diurnal pattern of blood pressure (BP), with higher nighttime BP for African-Americans than for Anglo-Americans despite similar daytime BP. We have hypothesized that the increased BP load in African-Americans contributes to the increased prevalence of hypertension and BP-induced target organ damage in adults. The purpose of this study was to examine the relationship between ABP patterns and renal function in healthy, normotensive black and white youths. The subjects were 22 African-American and 28 Anglo-American children and adolescents aged 10 to 18 years. Renal function was estimated by creatinine clearance (CCr). The African-American and Anglo-American subjects were similar in age, gender composition, casual BP, and CCr. The relationship between CCr and BP was not significant for casual BP or daytime BP for either group, or with nighttime BP in the Anglo-American subjects. In contrast, CCr was related negatively to both nighttime systolic BP (r = -0.47, beta = -1.21; P < .02) and nighttime diastolic BP in the African-American subjects (r = -0.45, beta = -2.13; P < .03). These results are consistent with our hypothesis.

Adolescent↗
PubMed1994

Race and sex differences in health locus of control beliefs and cardiovascular reactivity.

Examined the effects of race, sex, health locus of control (HLC), and the interactions of these variables on cardiovascular reactivity in 214 children. Participants completed the Multidimensional HLC scales for children. Systolic and diastolic blood pressures were measured at rest and during a reactivity task. Black boys had significantly higher scores on the powerful others (external HLC) subscale (p < 0.01) than white boys and girls. Furthermore, black boys showed greater systolic blood pressure reactivity when they were low on internality (vs. high) as compared to the other race-sex groups. Social and cultural factors may explain these differential findings across race and sex.

Adolescent↗
PubMed1994

Guidelines for exercise testing in the pediatric age group. From the Committee on Atherosclerosis and Hypertension in Children, Council on Cardiovascular Disease in the Young, the American Heart Association.

Exercise testing of children differs from adult exercise testing in many ways beyond the technical issues related to test performance that are addressed in this report. Disease processes that produce myocardial ischemia are relatively rare in children compared with adults. Exercise testing may be useful in these cases, but the use of testing to assess functional capacity or cardiac rhythms will be encountered more often. Although the precise role of exercise testing in patient evaluation or long-term management of the cardiac patient will vary somewhat from center to center, exercise testing is often essential to diagnose and to direct treatment in a wide variety of clinical problems. An understanding of the role of exercise testing for children with known or suspected heart abnormalities is an essential part of the training of pediatric cardiologists. The staff of the pediatric exercise laboratory should be available to discuss with the clinician when a test might be of value in a specific case in addition to providing advice about the specifics of the performance of the test and offering age- and size-appropriate normal data from the laboratory with test interpretation.

Arteriosclerosis↗
PubMed1994

Consistency of ethnic differences in children's pressor reactivity. 1987 to 1992.

In this prospective investigation, all children enrolled in the public third-grade classrooms of an entire county (n = 474) had blood pressure measured both at rest and during a stressful television video game. Examinations were repeated in 4 subsequent years when cohort children as well as newly enrolled children were in grades 4, 5, 7, and 8. Both cross-sectional and longitudinal analyses indicated that black children demonstrated significantly greater systolic and diastolic pressor reactivity than white children. These data suggest that ethnic differences in children's pressor reactivity presage ethnic differences in adulthood hypertension.

Black or African American↗
PubMed1994

Racial differences in the age-related increase in left ventricular mass in youths.

We determined the factors related to left ventricular mass adjusted for body size in 60 black (mean age, 13 +/- 2 years) and 40 white (mean age, 14 +/- 2 years) normotensive youths. The factors examined included age, sex, systolic blood pressure, diastolic blood pressure, plasma renin activity, plasma aldosterone concentration, and sodium and potassium intake as determined by 24-hour excretion. Sex (beta = 13.3, P < .003), age (beta = 2.88, P < .001), and systolic blood pressure (beta = 0.41, P < .02) were independent predictors in the sample as a whole, accounting for 37% of the variance of left ventricular mass adjusted for height. Separate analyses were performed for black and white subjects. In the black subjects, age (beta = 4.4, P < .004) followed by sex (beta = 11.85, P < .02) were independent factors, accounting for 43% of the variance of left ventricular mass adjusted for height. In contrast, in white subjects systolic blood pressure (beta = 0.4, P < .003) followed by sodium excretion (beta = 0.13, P < .05) were independent factors, with gender (beta = 8.89, P < .07) tending to account for 36% of the variance. Similar results were observed for left ventricular mass adjusted for body surface area. In conclusion, the age-related increase in adjusted left ventricular mass in black but not white youths may in part account for the early development of cardiovascular disease among the black population.

Adolescent↗
PubMed1994

Ambulatory blood pressure recordings in children and adolescents.

OBJECTIVE: To provide reference data for ambulatory blood pressure monitoring (ABPM) and to determine the influence of age, sex, and race on these values. METHODS: ABPM was performed on 300 healthy, normotensive boys and girls between the ages of 10 and 18 years, including 160 boys and 140 girls, of whom 149 were white and 151 were black. Mean systolic blood pressure (SBP), diastolic blood pressure (DBP), and heart rate (HR) while awake and during sleep were calculated for black and white boys and girls aged 10 to 12 years, 13 to 15 years, and 16 to 18 years. RESULTS: Boys compared with girls 10 to 12 years of age had higher mean (+/- SD) SBP (115 +/- 9 vs 112 +/- 9 mm Hg; P < .01) and DBP (67 +/- 7 vs 65 +/- 5 mm Hg; P < .01) while awake. Boys compared to girls 13 to 15 years of age had higher SBP while awake (116 +/- 11 vs 112 +/- 8 mm Hg; P < .01). Boys compared with girls 16 to 18 years of age had higher SBP while awake (125 +/- 12 vs 111 +/- 9 mm Hg); P < .01) and during sleep (116 +/- 11 vs 106 +/- 9 mm Hg). Comparisons within sex showed similar changes with age for boys and girls. Blacks compared with whites 13 to 15 years of age had higher SBP during sleep (109 +/- 11 vs 105 +/- 10 mm Hg; P < .01), and blacks compared with whites 16 to 18 years of age had higher DBP during sleep (66 +/- 7 vs 58 +/- 6 mm Hg; P < .01). Comparisons across age groups within race showed that blacks 16 to 18 years of age had higher SBP during sleep than blacks 10 to 12 years of age (109 +/- 11 vs 104 +/- 10 mm Hg), and higher DBP during sleep (66 +/- 7 mm Hg; P < .01) than blacks 10 to 12 years of age (61 +/- 7 mm Hg; P < .01) and 13 to 15 years of age (61 +/- 8; P < .01 mm Hg). The changes with age were not significant for white subjects. CONCLUSION: These results provide age-specific reference data for ABPM in youths. These values differ by sex (boys more than girls) and race (Blacks more than Whites).

Adolescent↗