Waist circumference to height ratio and left ventricular mass in children and adolescents.

OBJECTIVES: Waist circumference to height ratio, a measure of central obesity, is a better predictor of cardiovascular risk than body mass index in the paediatric population. Increased left ventricular mass secondary to obesity and hypertension increases the risk for death and cardiovascular disease in adults. Similar data on left ventricular mass are lacking among young patients with central obesity, as defined by waist circumference/height. The present study evaluates left ventricular mass in young patients with central obesity as defined by waist circumference/height. METHODS: A total of 156 patients, 2- to 20-years old, without evidence of structural heart disease were studied. As the left ventricular mass is related to age and gender, 52 patients with central obesity - waist circumference/height ⩾0.55 - were randomly matched for age and gender with 52 patients at risk for central obesity - waist circumference/height ⩾0.5 to <0.55 - and 52 patients with no central obesity - waist circumference/height <0.5. The left ventricular mass parameters measured by echocardiography were compared across the three groups. RESULTS: Patients with central obesity had significantly (p<0.05) increased Z scores for left ventricular mass, left ventricular mass/height2.7, and left ventricular mass/height1.7 compared with patients at risk for central obesity and patients with no central obesity. Z scores for left ventricular mass were higher among patients at risk for central obesity compared with patients with no central obesity. CONCLUSIONS: Left ventricular mass data of the present study support maintaining an ideal waist circumference/height <0.5. Aggressive efforts to identify and manage patients with central obesity are warranted.

Waist circumference to height ratio in children and adolescents.

BACKGROUND: Waist circumference (WC) to height ratio (WC/HT) is used as a measure of central obesity. However, the optimum ratio that will separate populations with high from low cardiovascular risk remains controversial. This investigation evaluates an optimum WC/HT value to define central obesity in children. METHODS: The sensitivity and specificity of WC/HT in 649 children (age 2-18 years) without evidence of heart disease were analyzed for WC and for body mass index (BMI). RESULTS: A WC/HT ≥0.5 resulted in sensitivity:specificity of 99%:72% for detecting central obesity and 83%:77% for detecting overweight (BMI ≥85th percentile) subjects. A value of WC/HT ≥0.55 yielded sensitivity:specificity of 80%:96% for detecting central obesity and 75%:94% for detecting subjects with obesity (BMI ≥95th percentile). CONCLUSIONS: The use of WC/HT between ≥0.5 and <0.55 identified subjects at-risk for central obesity and WC/HT ≥0.55 identified central obesity with a high probability.

Left ventricular mass in children and adolescents with elevated body mass index and normal waist circumference.

Children and adolescents with elevated body mass index (BMI) who have normal waist circumference (NWC) have a cardiometabolic risk profile similar to normal children. However, there is a lack of adequate information regarding their left ventricular mass (LVM). The present study was undertaken to evaluate LVM in children with elevated BMI with NWC. LVM was assessed by echocardiography in 247 children (age 2 to 19 years) without evidence of heart disease. Data on those who had elevated BMI with NWC (group 1, n = 80) were compared with matched normal controls with normal BMI who had NWC (group 2, n = 80) and children with elevated BMI with increased waist circumference (IWC; group 3, n = 87). Correlations, t tests, and linear regressions were used for statistical testing. LVM in children with elevated BMI with NWC was not significantly different from normal controls (97.6 ± 44.4 vs 100.7 ± 47.9 g, p = 0.6713, respectively); however, it was significantly less than that in subjects with elevated BMI who also had IWC (97.6 ± 44.4 vs 114.5 ± 47.8 g, p = 0.0193, respectively). Similar to normal controls, those subjects with elevated BMI with NWC had a stronger correlation between LVM and lean body mass (R(2) = 0.86 and 0.86, respectively) than subjects with elevated BMI with IWC (R(2) = 0.75). In conclusion, children with elevated BMI with NWC appear to have a similar LVM profile as children with normal BMI with NWC. The present study emphasizes the importance of measuring waist circumference in children with elevated BMI.

Prevention of necrotizing enterocolitis in preterm infants: a 20-year experience.

OBJECTIVE: Diet, indomethacin, and early use of dexamethasone have been implicated as possible causes of necrotizing enterocolitis and intestinal perforation. Because we seldom prescribe indomethacin or early dexamethasone therapy and we follow a special dietary regimen that provides late-onset, slow, continuous drip enteral feeding, we reviewed our 20 years of experience for the incidence of necrotizing enterocolitis and bowel perforation. METHODS: We reviewed data on all 1239 very low birth weight infants (501-1500 g) admitted to our level III unit over a period of 20 years (1986-2005), for morphologic parameters, necrotizing enterocolitis, bowel perforation, use of the late-onset, slow, continuous drip protocol, and indomethacin therapy. Outcome data were also compared with Vermont Oxford Network data for the last 4 years. RESULTS: In 20 years, 1158 infants received the late-onset, slow, continuous drip feeding protocol (group I), whereas 81 infants had either a change in dietary regimen, use of indomethacin, or early use of dexamethasone (group II). The rate of necrotizing enterocolitis in group I of 0.4% was significantly lower than that in group II of 6%. Group I, in comparison with the Vermont Oxford Network, had significantly lower rates of necrotizing enterocolitis (0.4% vs 5.9%), surgical necrotizing enterocolitis (0.4% vs 3.1%), and bowel perforation (0.35% vs 2.2%). CONCLUSIONS: Our 20-year experience with 1239 very low birth weight infants suggests strongly that the late-onset, slow, continuous drip feeding protocol and avoidance of indomethacin and early dexamethasone treatment contribute to the prevention of necrotizing enterocolitis.

Variabilidad de la frecuencia cardíaca en recién nacidos sanos / Heart rate variability in healthy newborns

Heart rate variability is becoming a useful clinical tool in both the management of critically ill infants as well as in the identification of their future morbidity. To facilitate this process, we have recently reported the normative data on commonly used parameters of heart rate variability from a large cohort of normal newborns. From 24-hour Holter monitors, these parameters can be measured by time domain, geometric, and frequency domain methods. We have found that geometric methods like Triangular index is an easy and reliable measure to study total heart rate variability in newborns. Many of the commercially available monitoring systems routinely provide SDNN and r-MSSD parameters as a part of their software package. Because of ease of use, vagal dependent time domain parameters like r-MSSD and sNN50 can be used as surrogates for high frequency power in newborns. Based on our normative data, full-term infants during the first week of life with SDNN < 30, r-MSSD < 14, or Triangular index < 8 should be further investigated.

La variabilidad de la frecuencia cardíaca (VFC) está convirtiéndose en una herramienta útil tanto para el manejo del recién nacido críticamente enfermo como para conocer su morbilidad futura. Para facilitar este proceso, recientemente comunicamos datos normatizados sobre los parámetros más utilizados de VFC, a partir de una amplia cohorte de recién nacidos normales. Con monitoreos Holter de 24 horas, estos parámetros pueden ser medidos en los dominios temporal, geométrico y de frecuencia. Encontramos que los métodos geométricos, como el índice triangular, constituyen una medida sencilla y confiable para estudiar la VFC total en recién nacidos. La mayoría de los sistemas de monitoreo disponibles comercialmente proveen los parámetros DENN y RMSCD como parte de su paquete informático. Debido a su fácil utilización, los parámetros de dominio temporal vagal dependiente como RMSCD y SNN50 (suma de todos los pares de intervalos N-N adyacentes que difieren en más de 50 ms, estandarizada para el total de intervalos válidos y la longitud del registro pueden ser usados como sustitutos de los de potencia de alta frecuencia en recién nacidos. Sobre la base de nuestros datos normatizados, los recién nacidos de término con DENN < 30, RMSCD < 14 o índice triangular < 8 deberían ser investigados durante las cinco primeras semanas de vida.

Effect of regular exercise after third decade on Doppler-derived left ventricular filling.

The present study prospectively evaluated filling properties of the left ventricle by pulsed tissue Doppler echocardiography in subjects >35 years old who exercised regularly. Data from 30 subjects (>35 years) who exercised regularly (group I) were compared with 30 age-matched subjects who did not exercise regularly (group II) and with data from 30 younger (22 to 35 years) subjects (group III). Except for the lower heart rate in group I, there were no significant differences between groups I and III; however, subjects in groups I and III, compared with group II, had significantly higher average early (E) waves (14.0 +/- 1.9 and 15.1 +/- 2.1 vs 12.5 +/- 2.6; p = 0.0001), lower average late (A) waves (8.2 +/- 1.8 and 8.2 +/- 1.5 vs 10.6 +/- 1.6; p <0.0001), and higher average E/A ratios (1.8 +/- 0.5 and 1.9 +/- 0.4 vs 1.3 +/- 0.4; p <0.0001), respectively. Regular exercise after the third decade precludes the age-related decrease in E waves, increase in A waves, and a decrease in the E/A ratio.

Comparison of myocardial function in children with body mass indexes >/=25 versus those <25 kg/m2.

Diastolic functions of the heart, measured by pulsed tissue Doppler echocardiography from 25 overweight and obese children, were compared with 91 children of normal weight who were 10 to 18 years old and had normal 2-dimensional echocardiographic examinations. Overweight and obese subjects, as compared with the control group, had a significant decrease in the peak early diastolic E wave at the ventricular septum (12.8 +/- 2.1 vs 13.8 +/- 1.8, p = 0.025) and a significant increase in the late diastolic A wave at the ventricular septum (7.3 +/- 1.8 vs 6.4 +/- 1.4, p = 0.016), lateral wall (7.8 +/- 4.3 vs 6.4 +/- 2.7, p = 0.000), and posterior wall (4.2 +/- 1.7 vs 3.6 +/- 0.9, p = 0.041). In addition, the overweight children had a significantly lower E/A ratio at the septum that was inversely related to body mass index.

Autonomic alterations in cocaine-exposed infants.

BACKGROUND: Heart rate variability (HRV) reflects autonomic control of the heart. After intrauterine cocaine exposure, asymptomatic newborn infants within 72 hours of life have decreased HRV. It is unknown whether these alterations are transient (acute effect) or persist in older infants and possibly reflect a teratogenic effect of cocaine. METHODS: This study prospectively evaluated HRV in 2- to 6-month-old infants who were exposed to cocaine in-utero (Group 1, n = 71). Their data were compared to normal controls (Group 3, n = 77) and to newborns exposed to drugs other than cocaine (Group 2, n = 89). Based on our previous study, heavy and light cocaine exposure was also defined a priori as the amount of cocaine used during the pregnancy that was more than or less than the 70th percentile, respectively. RESULTS: At the age of 2 to 6 months, infants with in-utero cocaine exposure had higher vagal tone and higher HRV (total power) than normal controls (no exposure to drugs). Most of this increase in vagal tone occurred in the light-cocaine-exposure group. HRV and vagal tone in the heavy-cocaine-exposure group were similar to the noncocaine-exposed group. CONCLUSIONS: At 2 to 6 months of age, asymptomatic infants exposed to cocaine in-utero have recovered from lower HRV seen within 72 hours of age. Infants exposed to light cocaine recovered by a rebound by increasing their vagal tone to above-normal levels. A similar response was blunted in heavily-cocaine-exposed infants. These alterations noted at follow up suggest a possible teratogenic effect of cocaine on the developing autonomic system.

Diastolic alterations in infants exposed to intrauterine cocaine: a follow-up study by color kinesis.

BACKGROUND: During the first 48 hours of life, newborn infants exposed to cocaine in utero have left ventricular diastolic segmental abnormalities. It is unknown whether these abnormalities are transient because of short-term effects or persist in older infants, possibly reflecting a teratogenic effect of cocaine. METHODS: This study prospectively evaluated global and segmental systolic and diastolic cardiac parameters by color kinesis. The patients were 2- to 6-month-old infants who were exposed to cocaine in utero (N = 56). Their data were compared with normal control patients with no intrauterine drug exposure (N = 60) and newborns exposed to drugs other than cocaine (N = 72). RESULTS: At the age of 2 to 6 months, there was no significant difference in the measured color kinesis parameters among the cocaine-exposed and the 2 control groups (infants prenatally exposed to other drugs and no drugs). Infants exposed to heavy cocaine prenatally, as compared with the noncocaine-exposed group, had a significant (P =.007) increase in septal fractional area change during left ventricular filling. CONCLUSIONS: At 2 to 6 months of age, infants have recovered from initial left ventricular diastolic segmental alterations seen in the first 48 hours of life except for the septal wall in the heavily cocaine-exposed group.

Heart rate variability by triangular index in infants exposed prenatally to cocaine.

BACKGROUND: In adults, heart rate variability triangular index (HRVi) is a highly reproducible measure of heart rate variability (HRV), which makes it more suitable for use in longitudinal studies. Although normative data have been published for newborns, studies in infants with pathological conditions are lacking. METHODS: From 1997 to 2000, within the first 4 days of life, we prospectively evaluated HRVi in cocaine-exposed asymptomatic newborns (N = 97) by Holter monitoring. Their data were compared with infants from two control groups (one with no in utero drug exposure, N = 102; the other with exposure to alcohol, nicotine, or marijuana but no cocaine, N = 111). RESULTS: In assessing concordance between and within operators for HRVi, the intraclass correlations were 0.983 (95% CI: 0.958, 0.994) and 0.997 (95% CI: 0.984, 0.999), respectively. Infants with in utero cocaine exposure had significantly (P < 0.0001) lower HRVi than those exposed to other drugs and to no drugs in utero. If abnormal HRVi is defined as < fifth percentile for the no drug exposed group (HRVi < 8), 10% of the cocaine-exposed newborns, in contrast to 2% in each of the control groups (P = 0.003) had abnormal values. CONCLUSION: HRVi is a reliable measure to study heart rate variability in newborns. Asymptomatic infants with in utero cocaine exposure have lower HRVi. Our study supports the clinical use of an abnormal HRVi as a value < 8 for newborn infants.

Parental involvement in pediatric cardiology outpatient visits.

There is a lack of information regarding parental involvement in subspecialty care of their offspring. We evaluated trends in 3,118 parental visits, accompanied by their children to a pediatric cardiology office during a 5-year period. Offspring accompanied both parents 29%, mothers alone 64%, and fathers alone 5% of the total visits. The rates were similar for first-time visits and this trend was similar across all 5 years. Children were significantly younger when accompanied by both parents than by individual parents. Mothers play a major role in a child's subspecialty care. Our findings have important educational, social, research, and marketing implications.

Diastolic filling abnormalities by color kinesis in newborns exposed to intrauterine cocaine.

Because cocaine crosses the placenta, we prospectively evaluated global and segmental systolic and diastolic cardiac function by color kinesis in clinically asymptomatic newborns who were exposed to cocaine in utero (group 1, n = 82). Their data were compared with normal controls (group 3, n = 87) and newborns exposed to drugs other than cocaine (group 2, n = 108). During left ventricular filling, newborns exposed to cocaine, compared with groups 2 and 3, had significantly (P <.05) higher global fractional area change (%) (76 +/- 10.3 vs 72 +/- 9.4 and 72 +/- 9.1, respectively), regional fractional area changes (%) for the anterior, septal, inferior, and lateral wall, and in the index of asynchrony (at 50% filling 13.2 +/- 5.8 vs 11.3 +/- 4.1 and 11.6 +/- 4.2, respectively). There were no significant differences in systolic function among the 3 groups. Prenatal cocaine exposure in asymptomatic infants leads to higher global and segmental fractional area changes and asynchrony during diastole. The significance and course of these alterations require further investigation.

Quantification of regional left ventricular wall motion in newborns by color kinesis.

BACKGROUND: Normal values for regional left ventricular wall motion, although documented in adults, have not been reported in healthy newborns. METHODS: This study prospectively evaluated global and segmental systolic and diastolic cardiac function by color kinesis in clinically asymptomatic healthy newborns. RESULTS: Eighty-eight asymptomatic infants who were less than 48 hours old were studied. Systolic and diastolic parameters of global and regional left ventricular function are reported as means +/- SD, medians, 5th and 95th percentiles to establish the normative values for newborns. The reported fractional area changes during systole and diastole are similar to the reported normal values for older subjects. Higher body surface area significantly correlated with an increased peak velocity during systole, and fractional area changes during filling of the lateral wall. CONCLUSIONS: Our report of left ventricular regional wall-motion characteristics of healthy newborns, as evaluated by color kinesis, may help in the objective evaluation and management of newborns suspected to have global or segmental ventricular dysfunction.

Heart rate variability in healthy newborn infants.

In adults and older children, heart rate variability (HRV) is frequently used to study autonomic function noninvasively. Normal values of HRV in newborn infants, however, are not widely available. This problem may be partially attributed to the lack of standardization of different methods. This study assessed HRV in normal newborn infants using 24-hour Holter monitoring. From 1997 to 2000, we prospectively evaluated frequency- (spectral analysis), geometric-, and time-domain indexes of HRV in normal term infants. Ninety-six asymptomatic infants who were <72 hours old were studied. Frequency-domain parameters (power in the high, low, very low, ultra low, and total frequency domains), a geometric parameter (HRV triangular index), and time-domain parameters (SDNN, SDANN, SDNNi, r-MSSD, s-NN50) are reported as means +/- SD, medians, and 5th and 95th percentiles to establish the normative values for newborns. A high degree of correlation (r > or = 0.85, p <0.0001) was noted among the 3 vagal tone dependent parameters, such as high-frequency power (frequency domain), r-MSSD, and s-NN50 (time domain). Our study supports the use of vagal dependent time-domain parameters like r-MSSD and sNN50 as surrogates for high-frequency power in newborns. Because the data are reported as means +/- SD, medians, and 5th and 95th percentiles, their use facilitates the study of parasympathetic and sympathetic activity in comparable populations.