Larry T. Mahoney

Coronary risk factors measured in childhood and young adult life are associated with coronary artery calcification in young adults: The muscatine study

OBJECTIVES This study was designed to estimate the prevalence of coronary artery calcification in young adult men and women and to examine the association between the presence of coronary artery calcification and coronary risk factors measured in childhood and young adult life. BACKGROUND Electron beam computed tomography is a sensitive, noninvasive method for detecting coronary artery calcification, a marker of the atherosclerotic process. Coronary artery calcification is associated with coronary risk factors in older adults. METHODS Subjects (197 men, 187 women) had coronary risk factors measured in childhood (mean age 15 years) and twice during young adult life (mean ages 27 and 33 years). Each underwent an electron beam computed tomographic study at their second young adult examination. RESULTS The prevalence of coronary artery calcification was 31% in men and 10% in women. Increased body size, increased blood pressure and decreased high density lipoprotein (HDL) cholesterol levels were the coronary risk factors that showed the strongest association with coronary artery calcification. Significant odds ratios for coronary artery calcification, using standardized risk factor measurements at a mean age of 33 years in men and women, respectively, were 6.4 and 13.6 for the highest decile of body mass index, 6.4 and 6.4 for the highest decile of systolic blood pressure and 4.3 and 4.7 for the lowest decile of HDL cholesterol. CONCLUSIONS Coronary artery calcification is more prevalent in men in this young adult population. Coronary risk factors measured in children and young adults are associated with the early development of coronary artery calcification. Increased body mass index measured during childhood and young adult life and increased blood pressure and decreased HDL cholesterol levels measured during young adult life are associated with the presence of coronary artery calcification in young adults.

Tracking physical fitness and physical activity from childhood to adolescence: the muscatine study.

PURPOSE Physical fitness and physical activity tracking data enhance our understanding as to when children settle into their long-term exercise and fitness patterns and, therefore. provide insight as to when programs focusing on preventing sedentary adults behaviors should be initiated. METHODS In this paper, the tracking of physical fitness and physical activity was examined in a 5-yr population-based study of children and adolescents in Muscatine, IA. Study subjects (N = 126) were pre- or early-pubescent at baseline (mean age boys 10.8 yr and girls 10.3 yr). Physical fitness was measured using direct determination of oxygen uptake and maximal voluntary isometric contraction while physical activity was assessed via questionnaire. RESULTS Boys classified as sedentary based on initial measurements of TV viewing and video game playing were 2.2 times more likely than their peers to also be classified as sedentary at follow-up. Tracking of most physical fitness and physical activity variables was moderate to high, indicating some predictability of early measurements for later values. Sedentary behavior tracked better in boys, whereas vigorous activity tended to track better in girls. CONCLUSION These observations suggest that preventive efforts focused on maintaining physical fitness and physical activity through puberty will have favorable health benefits in later years.

Randomized trial of liberal versus restrictive guidelines for red blood cell transfusion in preterm infants.

Objective. Although many centers have introduced more restrictive transfusion policies for preterm infants in recent years, the benefits and adverse consequences of allowing lower hematocrit levels have not been systematically evaluated. The objective of this study was to determine if restrictive guidelines for red blood cell (RBC) transfusions for preterm infants can reduce the number of transfusions without adverse consequences. Design, Setting, and Patients. We enrolled 100 hospitalized preterm infants with birth weights of 500 to 1300 g into a randomized clinical trial comparing 2 levels of hematocrit threshold for RBC transfusion. Intervention. The infants were assigned randomly to either the liberal- or the restrictive-transfusion group. For each group, transfusions were given only when the hematocrit level fell below the assigned value. In each group, the transfusion threshold levels decreased with improving clinical status. Main Outcome Measures. We recorded the number of transfusions, the number of donor exposures, and various clinical and physiologic outcomes. Results. Infants in the liberal-transfusion group received more RBC transfusions (5.2 ± 4.5 [mean ± SD] vs 3.3 ± 2.9 in the restrictive-transfusion group). However, the number of donors to whom the infants were exposed was not significantly different (2.8 ± 2.5 vs 2.2 ± 2.0). There was no difference between the groups in the percentage of infants who avoided transfusions altogether (12% in the liberal-transfusion group versus 10% in the restrictive-transfusion group). Infants in the restrictive-transfusion group were more likely to have intraparenchymal brain hemorrhage or periventricular leukomalacia, and they had more frequent episodes of apnea, including both mild and severe episodes. Conclusions. Although both transfusion programs were well tolerated, our finding of more frequent major adverse neurologic events in the restrictive RBC-transfusion group suggests that the practice of restrictive transfusions may be harmful to preterm infants.

The stability of children's physical activity as measured by accelerometry and self-report.

The Computer Science Application (CSA) accelerometer uses integrated circuitry and memory to provide a continuous recording of minute-by-minute movement counts. It has been previously validated as an objective monitor of childrens physical activity in field and laboratory settings. Our purpose was to derive accelerometry summary variables reflective of different physical activity intensity levels, evaluate the stability of these summary variables, and define the number of days needed to adequately measure usual physical activity. A secondary study purpose was to compare three self-report questionnaires to accelerometry. Thirty children (7-15 yr) wore accelerometers for 12 h.d-1 for 6 d. Daily summary variables of average movement count (total physical activity) and daily frequency of sedentary through vigorous activity were constructed. Intraclass correlation coefficients (R) and 95% confidence intervals (CI) were used to analyze the data. Accelerometry stability using 1 monitored day to represent usual physical activity was R = 0.42-0.47. When 6 d were used, stability increased to R = 0.81-0.84. Acceptable intraclass correlations and CI were achieved with 4 d of monitoring (R = 0.75-0.78, CI = 0.60-0.88). The self-report questionnaires were poorly to moderately correlated to accelerometry variables (r = -0.03-0.51). Data indicate that in field settings: 1) accelerometry can be used to assess the intensity of childrens activity and 2) 4 or more days of activity monitoring are needed to achieve satisfactory reliability.

Increased Carotid Intimal-Medial Thickness and Coronary Calcification Are Related in Young and Middle-Aged Adults The Muscatine Study

BACKGROUND Increased carotid intimal-medial thickness (IMT) and coronary artery calcification (CAC) are used as 2 markers of early atherosclerosis. Our objectives were to assess whether increased IMT and CAC are related and to determine the relationship between cardiovascular risk factors and carotid IMT in young adults. METHODS AND RESULTS A sample of 182 men and 136 women aged 33 to 42 years living in Muscatine, Iowa, underwent B-mode carotid ultrasound to determine the mean of 12 measurements of maximal carotid IMT. CAC was defined as calcification in the proximal coronary arteries in >/=3 contiguous pixels with a density of >/=130 HU. The mean IMT was 0.788 mm (SD 0.127) for men and 0.720 mm (SD 0.105) for women. CAC was present in 27% of men and 14% of women and was significantly associated with IMT in men (P<0.025) and women (P<0.005). With multivariate analysis, after adjustment for age, significant risk factors for carotid IMT were LDL cholesterol (P<0.001) and pack-years of smoking (P<0.05) in men and LDL cholesterol (P<0.001) and systolic blood pressure (P<0.01) in women. These risk factors remained significant after CAC was included in the multivariate model. CONCLUSIONS There is an association between increased carotid IMT and CAC and between cardiovascular risk factors and increased IMT in young adults. Carotid IMT may provide information in addition to CAC that can be used to identify young adults with premature atherosclerosis.

Left ventricular mass and exercise responses predict future blood pressure. The Muscatine Study.

Increased blood pressure and left ventricular mass are associated with increased morbidity and mortality in adults with coronary heart disease. To define the predictors of subsequent childhood blood pressure and left ventricular mass, serial echocardiograms and blood pressure responses during exercise were studied in 274 children aged 6 to IS years, whose systolic blood pressures were in the high, middle, or low range. Persistence of rank order for left ventricular mass and blood pressure, at rest and during exercise, was maintained over a mean follow-up period of 3.4 years, with correlations ranging from 0.33 to 0.44. Subsequent systolic blood pressure was best predicted from initial resting and maximal exercise systolic blood pressures and left ventricular mass. Subsequent left ventricular mass was best predicted from initial left ventricular mass and maximal exercise diastolic blood pressure, but resting systolic blood pressure did not add to this latter prediction. Since left ventricular mass relates best to exercise blood pressure and not to resting Mood pressure, left ventricular mass may provide an integrated view of the effects of blood pressure both at rest and during stress. We speculate that increased left ventricular mass in childhood may be an important predictor of subsequent hypertension and its consequences.

Childhood predictors for high adult blood pressure. The Muscatine Study.

In adult populations, elevated blood pressure is related to the development of stroke, renal disease, and occlusive atherosclerosis. The significance of blood pressure levels in childhood, unless extremely elevated, has not been related to disease outcomes. In a study carried out in Muscatine, Iowa, the risk of high blood pressure in young adult life was evaluated based on the observations of blood pressure and other factors made during the school-aged years. Subjects, 2445 in number, were first observed at ages 7 through 18 years and again between 20 and 30 years. During childhood, measurements of blood pressure, height, and weight were made on alternate years. At adult ages, the same measurements were again made and a health questionnaire was administered. Adult blood pressure was correlated with childhood blood pressure, body size, and change in ponderosity from childhood to adult life. Adult ponderosity was related to childhood ponderosity, and those who were most obese as adults showed the greatest increase in weight from their childhood years. These observations suggest that strategies to prevent the acquisition of excess ponderosity during childhood may be useful in preventing adult hypertension.

Factors Affecting Tracking of Coronary Heart Disease Risk Factors in Children.: The Muscatine Study

The public health implications of reducing or preventing the excess increase in blood pressure and the acquisition of obesity during childhood years are important. Many children with high blood pressure, particularly those who are initially obese or become obese as young adults and those with excess left ventricular mass for body size, become adults with high blood pressure. Although blood pressure and cholesterol have been shown to track during childhood and from childhood into the adult years, the use of repeated determinations along with measures of obesity and information concerning family history of diabetes and coronary heart disease can significantly add to the prediction of future elevated levels.

Balloon dilation valvuloplasty of bioprosthetic valves in extracardiac conduits

Six patients, aged 8 to 20 years, with valved right ventricle to pulmonary artery conduits were catheterized for balloon dilation valvuloplasty of stenotic and calcified bioprosthetic valves. Conduit stenosis was severe in all cases, with peak-to-peak systolic pressure gradients of 62 to 100 mm Hg (mean 79 mm Hg) and right ventricular systolic pressures of 87 to 115 mm Hg (mean 100 mm Hg). Three patients had good results, with residual peak-to-peak systolic pressure gradients of 20, 25, and 35 mm Hg. In two other patients, repeated balloon rupture before full inflation occurred, and residual gradients were high (55 and 60 mm Hg). One patient had substantial proximal and distal conduit obstruction in addition to valvular stenosis, and balloon dilation valvuloplasty was not attempted. No complications occurred in five patients; one patient required iliac vein exploration to remove an avulsed balloon fragment. Balloon dilation valvuloplasty can relieve bioprosthetic valve stenosis and postpone conduit replacement in some patients.

Comparative hemodynamic depression of halothane versus isoflurane in neonates and infants: an echocardiographic study.

The purpose of this study was to measure and compare the relationship of cardiovascular depression and dose during equal potent levels of halothane and isoflurane anesthesia in neonates (n = 19) (16.7 +/- 6.9 days) and infants (n = 54) (6.1 +/- 3.1 mo). Seventy-three children had heart rate, arterial blood pressure, and pulsed Doppler pulmonary blood flow velocity as well as two-dimensional echocardiographic assessments of left ventricular area and length recorded just before anesthesia induction. Anesthesia was induced by inhalation of increasing inspired concentrations of halothane or isoflurane in oxygen using a pediatric circle system and mask. During controlled ventilation, halothane and isoflurane concentrations were adjusted to maintain 1.0 MAC and then 1.5 MAC (corrected for age), and echocardiographic and hemodynamic measurements were repeated. A final cardiovascular measurement was recorded after intravenous administration of 0.02 mg/kg of atropine. All measurements were completed before tracheal intubation and the start of elective surgery. In neonates, 1.0 MAC concentrations of halothane and isoflurane decreased cardiac output (74% +/- 16%), stroke volume (75% +/- 15%), and ejection fraction (76% +/- 15%) similarly from awake levels. Decreases in cardiac output, stroke volume, and ejection fraction with halothane and isoflurane were significantly larger at 1.5 MAC (approximately 35% decreases from awake values) than at 1.0 MAC. Heart rate decreased significantly during 1.5 MAC halothane anesthesia (94% +/- 4%) but remained unchanged during isoflurane anesthesia. In infants, 1.0 MAC halothane and isoflurane decreased cardiac output (83% +/- 12%), stroke volume (78% +/- 12%), and ejection fraction (74% +/- 12%) when compared with awake measures.(ABSTRACT TRUNCATED AT 250 WORDS)