Sudhir Ken Mehta

Thrombosis and infection complicating central venous catheterization in neonates

To determine the risk of complication associated with Broviac central venous catheterization in neonates, we reviewed the records of 107 infants who were catheterized an average of 5 weeks after birth and cared for in our neonatal intensive care unit. Forty-five of the 107 neonates (42%) had one or more catheter-related complications. Infants with complications had significantly lower birth weights and gestational age, longer duration of catheterization, and more repeat catheterizations than infants without complications. The mortality rate in infants with complications was not different than that of infants without complications. The most common complications were thrombosis (23 neonates) and infection (20 neonates). The birth weight and the number of catheterizations were the best predictors of the risk of complications as determined by multiple regression analysis. We conclude that the risk of complication associated with central venous catheterization is high in our population of predominantly premature neonates; that the risk of complication is increased in neonates weighing less than 1,000 g or requiring more than one catheter; and that despite the high complication rate central venous catheterization was not associated with increased mortality in this population.

Transient myocardial ischemia in infants prenatally exposed to cocaine

This prospective study examined whether neonates of pregnant women who used cocaine during pregnancy are at a risk for the development of transient myocardial ischemia and altered autonomic function, as in adults. We studied 21 of 35 infants with a history of prenatal exposure to cocaine. The ST segment changes and heart rate variability were evaluated from three-channel Holter monitors within 48 hours of birth. The data were compared with those on 20 control infants with similar birth weight, gestational age, and postnatal age. Six infants (29%) who were exposed to cocaine in utero had transient ST segment elevation, versus only one infant (5%) from the control group (odds ratio = 7.6; 95% confidence interval, 1.14, 50.64). Heart rates, results of total power and low-frequency power spectral analyses for heart rate variability, and arrhythmias were not significantly different in the two groups. However, a lower ratio of low-to high-frequency power reflected increased vagal activity in cocaine-exposed infants. We conclude that cocaine use in pregnant mothers is associated with transient ST segment abnormalities in their infants. These abnormalities are consistent with transient myocardial ischemia.

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.

Incidence of thrombosis during central venous catheterization of newborns: A prospective study

Forty-two newborns were studied prospectively to determine the incidence of thrombosis due to central venous catheterization. Following Broviac catheter placement, the catheter tip, distal superior vena cava, and right atrium were evaluated by weekly two-dimensional echocardiograms. The presence of thrombosis was examined in relation to birth weight, gestational age, age and weight at the time of catheter placement, antithrombin III levels, and platelet counts. Six newborns (14%) were noted to have a thrombus by echocardiographic examination after the catheter had been in place for a median duration of 7 weeks. The infants with thrombus formation had significantly lower birth weights (887 +/- 231 v 1,409 +/- 766 g; P = .003) and gestational ages (27 +/- 2.4 v 30.3 +/- 4.3 weeks; P = .018) than those without thrombus. Their weights (757 +/- 203 v 1,832 +/- 1,098 g; P = .000) and ages (2.75 +/- 0.76 v 7.24 +/- 7.8 weeks; P = .002) at the time of catheter placement were also lower; the antithrombin III levels were lower at the time of catheter placement (0.32 +/- 0.08 v 0.06 +/- 0.31 U/mL; P = .001), but were normal for gestational and postnatal age. The presence of thrombosis was not related to the sex of the baby, the platelet count, or the duration of catheterization.

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.

Incidence of patent ductus arteriosus and patent foramen ovale in normal infants.

The incidence of POAF in this study was similar to that in other surgical cardiac populations despite our patients being younger than most surgical cohorts. However, patients with POAF in this study did not seem to have more acute symptoms (need for inotropic support, need for reoperation, duration of intensive care unit stay) than patients remaining in sinus rhythm. This longer hospital stay was generally attributable to ensuring adequate heart rate control, restoring sinus rhythm, and administering anticoagulation therapy. The treatment of POAF depends in large part on the timing, duration, and hemodynamic milieu. This small study does not support a prophylactic strategy, because one third of patients developing POAF were receiving amiodarone before operation. Our results suggest that POAF occurs in approximately 30% of patients with obstructive HC after septal myectomy. AF was not associated with a more complicated postoperative period and is relatively easily controlled or converted. The importance of age as a predictor of atrial fibrillation and flutter after coronary artery bypass grafting. Influence of clinical and hemodynamic variables on risk of supraventricular tachycardia after coronary artery bypass. of atrial fibrillation after coronary artery surgery. Current trends and impact on hospital resources. Atrial fibrillation increases length of stay and cost after cardiac surgery in low risk patients targeted for early discharge (abstr). The outcome of surgical treatment of hypertrophic obstructive cardiomyopathy. Experience over 15 years. Extent of clinical improvement after surgical treatment of hypertrophic obstructive cardio-myopathy. of primary atrial fibrillation and concomitant clinical and hemodynamic changes in patients with chronic heart failure: a prospective study in 344 patients with baseline sinus rhythm.ness of serial echocardiographic parameters for predicting the subsequent occurrence of atrial fibrillation. A s part of a study on the effects of in-utero cocaine exposure on the heart, a cohort of 104 full-term, healthy infants who did not have intrauterine drug exposure underwent extensive echocardiographic examination at birth and at 2 to 6 months of age. These studies were evaluated for the presence of a patent ductus arteriosus (PDA) and patent foramen ovale (PFO). Infants were eligible for the study if they were Ͻ72 hours old, weighed Ͼ1,500 g, and were between 33 and 42 weeks gestation. In all, 64 infants were excluded from the study because of various maternal and neonatal causes. We excluded infants born to mothers who used medications during pregnancy, such as bronchodilators, that may have affected the cardiovascular system. We …

Prenatal cocaine/polydrug exposure and infant performance on an executive functioning task

Executive functioning in cocaine/polydrug (marijuana, alcohol, tobacco) exposed infants was assessed in a single session, occurring between 9.5 and 12.5 months of age. In an A-not-B task, infants searched, after performance-adjusted delays, for an object hidden in a new location. Overall, the cocaine-exposed (CE) infants did not differ from non-CE controls recruited from the same at-risk population. However, comparison of heavier-CE (n = 9) to the combined group of lighter-CE (n = 10) and non-CE (n = 32) infants revealed significant differences on A-not-B performance, as well as on global tests of mental and motor development. Covariates investigated included socioeconomic status, marital status, race, maternal age, years of education, weeks of gestation, birth weight, as well as severity of prenatal marijuana, alcohol, and tobacco exposure. The relationship of heavier-CE status to motor development was mediated by length of gestation, and the relationship of heavier-CE status to mental development was confounded with maternal gestational use of cigarettes. The relationship of heavier-CE status to A-not-B performance remained significant after controlling for potentially confounded variables and mediators, but was not statistically significant after controlling for the variance associated with global mental development.

Altered diastolic function in asymptomatic infants of mothers with gestational diabetes.

Left and right ventricular filling was studied prospectively in 50 full-term (39.4 ±1.3 wk) asymptomatic newborns of mothers with gestational diabetes mellitus (GDM). Their data were compared with those of 80 asymptomatic full-term (39.8 ±1.2 wk) infants who served as control subjects. Infants were examined in the immediate newborn period (<48 h) and then again at 2–4 and 6–9 wk. Although mean weight, length, and gestational age did not differ, the mean ± SD left ventricular dimensions during diastole (1.73 ± 0.15 vs. 1.81 ± 0.18 cm, P = 0.007) and systole (1.22 ± 0.15 vs. 1.31 ± 0.17 cm, P = 0.004) were significantly lower in infants of mothers with GDM compared with control infants. Diastolic measurements suggested a shift from the early diastolic filling of the ventricle to the later period of atrial systole in infants of mothers with GDM. A lower initial one-third area fraction and a higher peak flow velocity and velocity time integral during atrial systole were noted at the mitral valve in infants of mothers with GDM. These changes had resolved by 2–4 wk of age. The altered diastolic filling patterns in infants of mothers with GDM indicate poor myocardial relaxation and/or decreased passive compliance of the ventricular myocardium. These alterations were observed in asymptomatic infants in the absence of left ventricular or septal hypertrophy. If exposed to significant stress such as asphyxia or sepsis, the observed myocardial dysfunction could lead to higher morbidity in these infants.

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.

Normal values and methodologic recommendations for signal-averaged electrocardiography in children and adolescents.

Signal-averaged electrocardiography was performed in 153 normal children and adolescents (1 day to 18.3 years old) to examine the effects of age, sex, and race on different electrocardiographic variables, and to evaluate whether the current methods for analysis of the signal-averaged electrocardiogram are applicable to small children. Tracing with inaccurate automatic determination of the QRS end point or high noise levels were excluded. Filtered QRS duration, root-mean-square voltage, and low-amplitude signal duration were measured using 25, 40, and 80 Hz filters. All variables were significantly different (p <0.01) in infants compared with subjects aged >15 years. These differences gradually resolved with increasing age. Sex differences were present for some variables in adolescents only, and there was no significant race-related difference. Because of the shorter QRS duration, the terminal activities were more accurately reflected at the terminal duration of 30 ms in infants and 35 ms in children aged at least 1 year to <6 years. Normative data for filtered QRS duration, root-mean-square voltage, and low-amplitude signal duration are provided for different age groups.