Altered systolic and diastolic function in children after "successful" repair of coarctation of the aorta

We investigated whether left ventricular (LV) structural or functional abnormalities persist in children on long-term follow-up after successful correction of coarctation of the aorta. Two-dimensional directed M-mode and Doppler echocardiographic examinations were performed in 11 such subjects and 22 age-matched control subjects. Digitized tracings were made from M-mode recordings of the LV and Doppler mitral valve inflow recordings to measure septal, posterior wall, and LV dimensions, LV mass, shortening fraction, peak shortening and lengthening velocities, diastolic filling time, peak E velocity, peak A velocity, and velocity time integrals. Despite group similarities in age, body size, and systolic blood pressure, greater fractional shortening (p = 0.0001), indexed peak shortening velocity (p less than 0.001), and greater LV mass index (p less than 0.05) were seen in the coarctation group in the face of lower LV wall stress (p = 0.0001). LV mass index correlated with the resting arm-leg gradient, which ranged from -4 to +10 mm Hg. The coarctation group had decreased early filling (p less than 0.006) with compensatory increased late diastolic filling (p less than 0.05). Diastolic filling abnormalities were prominent in the older coarctation subjects and were related to both systolic blood pressure (p less than 0.001) and LV mass index (p less than 0.01). Despite apparently successful repair of coarctation of the aorta, persistent alterations in both systolic and diastolic LV function and LV mass are present in children at long-term follow-up, which are related to the resting arm-leg gradient.(ABSTRACT TRUNCATED AT 250 WORDS)

Genetic analysis of anthropometric measures in 11-year-old twins: the Medical College of Virginia Twin Study

We have conducted a cross-sectional analysis of the genetic and environmental contributions to the variance of anthropometric measurements in children during early adolescence. Univariate path analysis was used to estimate the relative contributions of genes, individual environment, and family environment to measures of childhood obesity in 259 11-y-old Caucasian twin pairs. Triceps, subcapular, and suprailiac skinfold thicknesses, as well as waist circumferences, ht, and wt were measured in a standardized protocol. In this sample, a parsimonious model that included only additive genetic effects and environmental factors unique to the individual provided an adequate explanation for the variation in ht, wt, quetelet index, and subscapular and triceps skinfolds. In this largely preadolescent population, different magnitudes of genetic effects were seen in males and females for waist circumference, biiliac diameter, and suprailiac skinfold.

Lipoprotein and oxygen transport alterations in passive smoking preadolescent children. The MCV Twin Study

We investigated the cardiovascular effects of lifelong passive cigarette smoke exposure in preadolescent children and examined the following questions: 1) Is systemic oxygen transport altered? 2) Are coronary heart disease risk factors adversely affected? We recruited 216 families from the MCV Twin Study; 105 had at least one smoking parent. Serum thiocyanate and cotinine levels were used as measures of smoke exposure in the children and thiocyanate was proportional to the number of parental cigarettes smoked each day (p = 0.0001). Paternal smoking had no effect on these measures. Whole blood 2,3-diphosphoglycerate was higher in smoke-exposed than unexposed children (p less than 0.01) and was related to the thiocyanate level (p less than 0.02). High density lipoprotein (HDL) cholesterol was lower in passive smoking children (p less than 0.05); the HDL2 subfraction was reduced in passive smoking boys, while the HDL3 subfraction was reduced in passive smoking girls. Significant adverse alterations in systemic oxygen transport and lipoprotein profiles are already present in preadolescent children exposed to long-term passive cigarette smoke, primarily from maternal smoke. Children with long-term exposure to passive smoke may be at elevated risk for the development of premature coronary heart disease.

Univariate genetic analysis of blood pressure in children (the Medical College of Virginia Twin Study)

The relative contributions of genetic, individual environmental and shared environmental effects on resting blood pressure (BP) and heart rate (HR) were studied in prepubescent twins. The study population consisted of 251 caucasian 11-year-old twin pairs. Correlations were higher for all variables in monozygotic twins compared to dizygotic twins; this is consistent with a significant genetic effect. Path analysis revealed that the model of additive genetic and individual environmental effects fit systolic BP, diastolic BP and HR. In boys and girls, sex-specific genetic effects controlled systolic BP. The magnitudes of the sex-specific genetic effects on systolic BP were similar in both boys and girls and accounted for 66% of the variance. In boys, for diastolic BP, genetic effects accounted for 64% of the variance while in girls they accounted for 51%. These results provide no evidence for different genetic effects on HR in boys or girls. No shared environmental effects were detected. The large sample size and design, using different-sex dizygotic twins of the same age, establish that genes play an important role in the influence of resting BP and HR and that there are sex-specific genetic contributions in early pubertal children.

The management of the family at high risk for coronary heart disease

The family at risk has at least one member who has (1) hyperlipidemia; (2) low HDL2-cholesterol; (3) essential hypertension; (4) a family history of premature CHD; or (5) actively smokes. The predictive value of CHD risk factors in adults is well documented and quantified. Familial aggregation, genetic studies, and tracking of blood pressure provide evidence that children born to families with a high prevalence of hypertension or who as adolescents track in the upper part of the blood pressure distribution are themselves at risk for hypertension. Similarly, familial aggregation, tracking, and autopsy studies provide evidence for the relationship of serum lipids to the subsequent development of coronary atherosclerosis. Smoking by parents adversely affects the hearts and lungs of children. In addition, the child with a parent who smokes is more likely to become an active smoker. Preventive strategies are now available to the pediatrician to reduce the risk of premature CHD.

Identification of high risk relatives for coronary heart disease

The family at increased risk for future coronary heart disease is the family with a member who has 1) had one or more myocardial infarctions before age 55 years; 2) has levels of LDL cholesterol greater than 75th percentile for age; 3) has excessively low levels of HDL2 cholesterol; 4) has hypertension or has had a stroke, or both; 5) has excessive weight at any age and excessive weight gain during adulthood, or 6) smokes in the household.

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 15 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 blood 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.

Aortic stiffness: a new Doppler echocardiographic measure predictive of systolic blood pressure in children

Aortic stiffness, the maximal frequency shift in the descending aorta divided by the Doppler acceleration time, was studied in 384 eleven year old twin children. The extent to which this measurement provided a prediction of systolic blood pressure that was independent of body size, heart rate, cardiac contractility and left ventricular mass was investigated. Aortic stiffness, after adjustment for height and weight, correlated significantly with systolic blood pressure (r = 0.22, p less than 0.01), but not with diastolic blood pressure. The short- (r = 0.82) and longer- (r = 0.68) term reproducibility of aortic stiffness was high. This measure appears to be a more powerful predictor of systolic blood pressure than is left ventricular mass. Aortic stiffness is a highly reproducible Doppler variable that may explain in part the contribution of the aortic wall elastic properties to the level of systolic blood pressure in preadolescent children at rest.

Measurement of left ventricular wall mass in pediatric populations

This paper reviews the techniques for obtaining technically adequate echocardiograms for epidemiologic studies. When these techniques were applied to studies of pediatric populations the following objectives were achieved: reproducible echocardiograms, observations about the relationship of echocardiographic variables to cardiovascular variables, and information about the relationship of echocardiographic and electrocardiographic variables to each other and to blood pressure. We documented the precision of M-mode left ventricular chambers and dimensions, interobserver and intraobserver variability, and the day-to-day variability of these measures. Left ventricular wall mass was significantly larger than expected for age and body size in children with persistently elevated blood pressure. The relationship between the echocardiographic and electrocardiographic variables was poor. Moreover, the electrocardiographic measures of ventricular hypertrophy did not correlate with blood pressure.

Hemodynamics in childhood hypertension

Children with elevated systolic blood pressure have a wide range of cardiac output. We investigated the mechanisms regulating resting and exercise blood pressure in 264 children who were selected from the low, middle, and upper quintile of the distribution of blood pressure of an entire school population. We identified patterns of response to exercise that correlated both with resting cardiac output and resting blood pressure. During isometric exercise, systolic blood pressure adjusted for age and body size increased in all groups. The low group mean pressure remained significantly lower than the high group's pressures throughout the entire exercise period. Body size adjusted group systolic and diastolic blood pressure level differences existed during dynamic exercise. The product of the systolic blood pressure times the heart rate in the high blood pressure group was significantly higher throughout dynamic exercise than in the other two groups. Elevated resting resistance was correlated with elevated resistance during isometric exercise and elevated diastolic blood pressure during dynamic exercise. Cardiac index had a significant negative correlation to age (r = -0.58) at all levels of blood pressure. This observation, in children, lends some support to the concept of evolution from a hyperkinetic circulation in early childhood to a circulation with lower cardiac output and more elevated systemic vascular resistance at an older age.

The cardiovascular responses to exercise in children across the blood pressure distribution. The Muscatine study

Children with elevated systolic blood pressure have a wide range of cardiac output. To better understand the mechanisms regulating resting and exercise blood pressure, we investigated the cardiovascular responses to both dynamic and isometric exercise in 264 children who were selected from the low, middle, and upper quintile of the distribution of blood pressure of an entire school population. We sought to identify patterns of response to exercise that correlated with both resting cardiac output and resting blood pressure. During isometric exercise, systolic pressure adjusted for age and body size increased in all groups. The low group's mean pressure remained significantly lower than the high group's pressure throughout the entire exercise period. Body size adjusted group systolic and diastolic blood pressure level differences exist during dynamic exercise. The product of the systolic blood pressure times the heart rate, in the high blood pressure group, was significantly higher throughout dynamic exercise than in the other two groups. Elevated resting resistance is correlated with elevated resistance during isometric exercise and elevated diastolic blood pressure during dynamic exercise. Cardiac index had a significant negative correlation to age (r = -0.58) at all levels of blood pressure. This observation, in children, lends some support to the concept of the evolution from a hyperkinetic circulation in early childhood to a circulation with lower cardiac output and more elevated systemic vascular resistance at an older age.

Electrocardiographic measures of left ventricular hypertrophy in children across the distribution of blood pressure: the Muscatine study

We sought to test the effectiveness of the ECG as a measure of increased left ventricular wall mass in children with high blood pressure. One hundred eighty-one children, ages 9-18 years, were selected from the lowest, middle and highest quintile of systolic blood pressure from the Muscatine Study, based upon two biennial school screenings. After correction for age, sex, height, weight and skinfold thickness, children with the highest blood pressure had increased echocardiographic left ventricular wall mass (p less than 0.02). Voltage measurements of maximum R and S waves in the standard and precordial leads were measured by computer. We correlated blood pressure and echocardiographic measurements of the interventricular septum, left ventricular posterior wall and left ventricular wall mass to electrocardiographic combinations used to predict left ventricular hypertrophy in both children and adults. The electrocardiographic correlations ranged from -0.01 to + 0.17. Poor correlations were found between electrocardiographic measures and blood pressure, left ventricular wall thickness or left ventricular wall mass. Skinfold thickness and weight had negative correlations, suggesting a damping effect upon measured voltage. We conclude that the echocardiogram is a more sensitive measurement of increased left ventricular mass than the ECG in children with elevated blood pressure.

Repair of large ventricular septal defects in infants and small children

It is possible to achieve excellent results for primary closure of ventricular septal defects regardless of the age of the patients when surgical intervention is required. Thirty-two severely symptomatic patients, age 1-24 months, with large ventricular septal defects (m Qp/Qs = 3.4, m R VSD = 4.0), had primary repair of the defects with one (3%) hospital death. Seven patients (22%) had increased pulmonary vascular resistance ranging from 5.4 to 12 units/m2. It was possible to close the ventricular septal defect through the right atrium in 26 patients (81%). Pulmonary artery banding was not performed in any patient with isolated ventricular septal defect during the period of this study. The 31 survivors have been followed an average of four years, and 30 of them are remarkably improved and remain New York Heart Association Class I or II. Only one patient, with obstructive pulmonary vascular disease (pulmonary resistance = 12 U/m2), died suddenly 16 months after operation. Follow-up catheterization was offered to all patients, and to date, 18 (60%) have been restudied. These hemodynamic data show that pulmonary vascular resistance after surgery is usually normal or only minimally elevated; except for one patient with a large residual ventricular septal defect, functionally significant left to right shunts were eliminated. These results and the analysis of results of combined series reported in the literature for primary and staged operations for the continued practice of primary repair of isolated large ventricular septal defects in infants and children who require surgery.

Spontaneous closure of a coronary artery fistula in childhood

An infant with a symptomatic coronary artery fistula, documented by angiography, is presented. By age 5 years, clinical evidence of the fistula was no longer present. Repeat cardiac catheterization confirmed spontaneous closure of the coronary artery fistula. More information regarding the natural history of a coronary artery fistula is required before an elective surgical approach can be recommended in all asymptomatic children.

Communicating hydrocephalus secondary to venous complications following intraatrial baffle operation (mustard procedure) for d-transposition of the great arteries

A 39-month-old male had macrocephaly and communicating hydrocephalus secondary to superior vena cava (SVC) obstruction which was a postoperative complication of an intraatrial baffle operation (Mustard procedure) performed at age 10 months. Computerized tomography revealed progressive hydrocephalus. Cardiac catheterization showed an SVC pressure of 24 mm Hg. IVC and systemic vein atrium pressures were 5 mm Hg. Cineangiograms showed huge azygos collaterals from SVC to IVC. The operation was revised using a Dacron baffle instead of the original pericardial baffle. Nine months postoperatively, the head circumference was 55.0 cm and there was no clinical evidence of SVC obstruction.

Left ventricular hypertrophy in children with blood pressures in the upper quintile of the distribution. The Muscatine Study

From echocardiography measurements of left heart dimensions, cardiac output was estimated in 264 school children whose systolic blood pressure persisted in the lowest, middle, or highest quintile of the distribution for their age and sex. Children with blood pressure in the upper quintile were taller, heavier, and more obese. Echocardiographically determined left ventricular wall mass, corrected for body size, was significantly greater in these children than those in the lower quintiles of blood pressure. These children displayed a continuum of cardiac output. Those with the highest cardiac output in the upper blood pressure quintile had the greatest left ventricular wall mass.

Effect of mitral valvular regurgitation on transthoracic impedance cardiogram

Mitral valvular regurgitation consistently modified the wave form of the first derivative of the transthoracic impedance cardiogram. The transthoracic impedance cardiogram was recorded in 23 control subjects (group 1), and 23 patients with isolated mitral regurgitation (group 2). Simultaneous transthoracic impedance cardiogram, electrocardiogram, and mitral valve echocardiograms in group 1 showed that the primary diastolic wave ("O") of the transthoracic impedance cardiogram occurred synchronously with the maximal opening of the mitral valve. In group 2, the primary systolic wave (dZ/dt max) was diminished, and the "O" of the transthoracic impedance cardiogram was raised. The area under the systolic wave of the transthoracic impedance cardiogram (S) and the area under the diastolic opening of the transthoracic impedance cardiogram (D) were measured and the ratio D/(D + S) calculated. This ratio, called the mitral regurgitation fraction was (0.50 +/- 0.14) in group 2 which was higher than that found in group 1 control subjects (0.11 +/- 0.08). The mitral regurgitation fraction (15 to 77%) determined by the impedance method was closely correlated with the mitral regurgitation fraction (20 to 74%) obtained during cardiac catheterisation; it also increased during isometric handgrip and decreased during amyl nitrite inhalation. In three mitral regurgitation patients the transthoracic impedance cardiogram returned to normal configuration after surgical implantation of a prosthetic mitral valve. These data suggest that the transthoracic impedance cardiogram is quantitatively altered in patients with mitral regurgitation.