Hypoplastic left heart syndrome: attitudes among pediatric residents and nurses towards fetal and neonatal management.

OBJECTIVE: To determine the attitudes of pediatric residents and nurses towards fetal/neonatal management of hypoplastic left heart syndrome (HLHS), and their basis. METHODS: Pediatric residents and nurses from three cardiac centers completed a survey with hypothetical scenarios in which their own fetuses or newborns had HLHS. While Institution A performs many HLHS surgeries, Institution C performs very few. RESULTS: A total of 43% of residents and 50% of nurses would terminate an affected pregnancy. More experience (4 to 7 years, p = 0.04; >7 years, p = 0.05) and employment at institution C (p = 0.04) predicted termination. Expected better quality of life (QOL) (p = 0.02) and five-year survival >50% (p = 0.06) predicted not terminating. Postnatally, 48% of residents and 68% of nurses would choose, or seriously consider, comfort care. Marriage (p = 0.04) and more experience (4 to 7 years, p = 0.04; >7 years, p = 0.02) predicted choosing comfort care. Asian/Pacific Islander descent (p = 0.01) and expected 5-year survival >50% (p = 0.02) predicted choosing surgery. CONCLUSIONS: Approximately one-half of the pediatric residents and nurses surveyed would choose termination of pregnancy or seriously consider declining neonatal surgery, if their own fetus or infant had HLHS. These attitudes reflect perceptions of long-term QOL and survival. These attitudes may be of interest to caregivers who care for HLHS patients.

High-Q-preserving coupling between a spiral and a semicircle micro-cavity.

We present an efficient design for direct coupling between a spiral-shaped and a semicircle-shaped microcavity (micro-cavity) as an alternative to traditional evanescent wave coupling for planar integrated photonic technology. We observe the preservation of the high Q-value of the spiral oscillator when coupled to a semicircle under current injection using an AlGaAs single-quantum-well heterostructure. With slight alterations to the directly coupled micro-cavity configuration, such as coupling shape and overlap distance, the number of observed modes and output intensity are changed. AlGaAs and InGaN spiral-shaped microcavities have unidirectional emission normal to the spiral notch.

Current practice of exercise stress testing among pediatric cardiology and pulmonology centers in the United States.

The objective of this study was to characterize current practice patterns for clinical exercise stress testing (EST) in children in the United States. We conducted a survey of 109 pediatric cardiology programs and 91 pediatric pulmonology programs at children's hospitals or university hospitals in the United States. A total of 115 programs from 88 hospitals responded (response rate, 58%). A higher percentage of cardiology programs (98.7%) have exercise laboratories compared with pulmonology programs (77.5%). Sixty-three percent of respondents have both a treadmill and a cycle ergometer. A larger proportion of respondents (76%) rely primarily or exclusively on treadmill, whereas a smaller number use cycle ergometer (24%). Sixty-seven percent of respondents reported that they include metabolic measurements in EST protocols. Respondents have varying minimum age criteria for EST, with 9% reporting < or = 4 years, 25% reporting 5 years, 31% reporting 6 years, 16% reporting 7 years, and 20% reporting > or =8 years. Programs using cycle ergometers tend to test children at a younger age and to measure metabolic parameters. Seventy-nine percent of respondents use Bruce and modified Bruce protocols. Institutional protocols are used by 14%. Ninety percent of respondents use technicians to perform EST and 8% use nurses, but 76% require physician presence during testing. The majority of respondents (57%) perform < 100 pediatric tests per year. There are wide variations in the current practice of EST among pediatric subspecialty programs in the United States. Treadmills are used more frequently than cycle ergometers, and Bruce and modified Bruce protocols are commonly used. Most survey respondents measure metabolic parameters during EST.

Chest radiography and the evaluation of the neonate for congenital heart disease.

We assessed the utility of the chest film as a screening tool for term and preterm neonates with suspected structural heart disease. Three independent observers, blinded to patient diagnosis, retrospectively evaluated the initial chest film for each of 128 consecutive neonates with suspected heart disease (gestational age, 23-42 weeks; birth weight, 500-4,621 g) who had undergone both chest radiography and echocardiography. These evaluations were subsequently compared with the results of the respective echocardiograms, read by board-certified pediatric cardiologists blinded to the chest film and chest film interpretation. Kappa statistics demonstrated moderate correlation (0.42-0.48) among different observers in their interpretation of the chest films but poor correlation (0.15-0.34) between chest radiography and echocardiography. The chest film had a low sensitivity for structural heart disease (26-59%), with a negative predictive value of 46-52%. Among neonates less than 2 kg or younger than 35 weeks of gestation, the chest film had still lower sensitivity for detecting heart disease. Despite agreement among observers in chest film interpretation, the chest film does not function as a screening test for neonates with suspected heart disease, particularly in small or premature neonates. In neonates with suspected heart disease, echocardiography should be considered, even in patients with chest films that do not suggest congenital heart disease.

Deciphering output coupling mechanisms in spiral microcavities with femtosecond light bullets.

A pump-probe two-photon-excited fluorescence technique deciphers in space and time the propagation of ballistic wave packets sustained by whispering-gallery modes (WGMs) in a spiral-shaped microcavity. Diffraction on the spiral discontinuity does not prevent the WGMs from closing. The resultant average Q of the resonator is 3 x 10(4) +/- 50%. Experimental results are compared with numerical simulations, providing evidence of a new contribution to output coupling: Part of the WGM evanescent wave is reflected at the spiral notch and leads to a propagating wave at an angle that matches the previously observed laser emission direction in 4-dicyanomethylene-2-methyl-6-(p-dimethylaminostyryl)-4H-pyran-doped poly(methyl methacrylate) and InGaN spiral lasers.

Prenatal screening for congenital heart disease using real-time three-dimensional echocardiography and a novel 'sweep volume' acquisition technique.

OBJECTIVES: Conventional prenatal screening for congenital heart disease (CHD) involves a time-consuming and highly operator-dependent acquisition of the four-chamber view and outflow tracts. By acquiring the entire fetal heart instantaneously as a single volume, real-time three-dimensional echocardiography (RT3DE) may facilitate fetal cardiac screening. METHODS: Four reviewers, each experienced with fetal cardiac imaging, blindly and independently evaluated a single cardiac volume from each of 18 fetuses (11 normal, seven with CHD). Two-dimensional echocardiography served as the gold standard. Three-dimensional evaluation of each fetus included a series of volume acquisitions lasting 2-6 s each. A 'sweep volume' technique was developed to fit larger hearts into a single non-gated volume. RESULTS: RT3DE had a high sensitivity for detecting CHD (93%), with only a single case being missed by two observers. Specificity for CHD was low (45%), with a high rate of 'cannot determine' responses and false positive artifacts. CONCLUSIONS: These preliminary results suggest that RT3DE has the potential to function as a screening tool for fetal heart disease. However, artifacts must be recognized and minimized, resolution must improve, and substantial training will be necessary prior to widespread clinical use.

Direct evidence of open ray orbits in a square two-dimensional resonator of dye-doped polymers.

Lasing has been observed in optically pumped 4-dicyanomethylene-2-methyl-6-( p-dimethylaminostyrl)-4H-pyran-doped poly(methyl methacrylate) square-shaped micropillars that allow four-bounce closed and open ray orbits with internal incident angle theta(inc) > theta(c) (the critical angle for total internal reflection) and with the associated surface waves that emit at the four corners. We also detect strongly TE-polarized and spatially varying emission from the square sidewalls that is due to leaky open ray orbits with theta(inc) near but less than theta(c) for two of the four bounces. By selectively pumping the square microcavity with a stripe-shaped beam, we excite different four-bounce ray orbits.

Fresnel filtering in lasing emission from scarred modes of wave-chaotic optical resonators.

We study lasing emission from asymmetric resonant cavity GaN microlasers. By comparing far-field intensity patterns with images of the microlaser we find that the lasing modes are concentrated on three-bounce unstable periodic ray orbits; i.e., the modes are scarred. The high-intensity emission directions of these scarred modes are completely different from those predicted by applying Snell's law to the ray orbit. This effect is due to the process of "Fresnel filtering" which occurs when a beam of finite angular spread is incident at the critical angle for total internal reflection.

Echocardiographic findings of hypertrophic cardiomyopathy in children after orthotopic liver transplantation.

This study was carried out to compare echocardiographic findings of children taking tacrolimus and cyclosporin A (CsA) after orthotopic liver transplantation (OLT). Echocardiograms of 19 children were reviewed during hospitalizations after OLT, and echocardiograms were performed on 23 children who returned to the clinic for a routine follow-up visit after OLT. Measurements were made of the left ventricle (LV) end-diastolic dimension, and of the thickness of the LV free wall (LVFW) and the inter-ventricular septum (IVS). From these measurements, the LV mass was calculated. LV outflow gradient was measured by using Doppler interrogation. Comparisons were made between patients on CsA and patients on tacrolimus. Children with hypertrophic cardiomyopathy (HCM) were identified. Two patients from the in-patient tacrolimus group were found to have HCM. These two patients had asymmetric septal hypertrophy with dynamic LV outflow obstruction and were successfully treated with propranolol, with or without discontinuing tacrolimus. In the out-patient studies, there was no difference in LVFW and IVS thickness, or LV mass index, between children on CsA and children on tacrolimus. Hence, tacrolimus is associated with the development of HCM in children. The effect of tacrolimus on HCM development may be acute and temporary. More data are needed to determine the incidence of HCM in children on tacrolimus therapy and to establish guidelines for clinicians who follow-up these children.

Fluorescence from airborne microparticles: dependence on size, concentration of fluorophores, and illumination intensity.

We measured fluorescence from spherical water droplets containing tryptophan and from aggregates of bacterial cells and compared these measurements with calculations of fluorescence of dielectric spheres. The measured dependence of fluorescence on size, from both droplets and dry-particle aggregates of bacteria, is proportional to the absorption cross section calculated for homogeneous spheres containing the appropriate percentage of tryptophan. However, as the tryptophan concentration of the water droplets is increased, the measured fluorescence from droplets increases less than predicted, probably because of concentration quenching. We model the dependence of the fluorescence on input intensity by assuming that the average time between fluorescence emission events is the sum of the fluorescence lifetime and the excitation lifetime (the average time it takes for an illuminated molecule to be excited), which we calculated assuming that the intensity inside the particle is uniform. Even though the intensity inside the particles spatially varies, this assumption of uniform intensity still leads to results consistent with the measured intensity dependence.

Multimode resonances in square-shaped optical microcavities.

Square-shaped two-dimensional optical microcavities (micro-cavities) were investigated for possible applications as filters for dense wavelength-division multiplexing. Multimode cavity resonances were observed in the elastic scattering of approximately 200-microm square-shaped micro-cavities in fused silica. Based on a two-dimensional k-space representation, we accounted for the multimode spectrum by different normal modes with rays confined by total internal reflection. The cavity-mode trajectories need not be closed after each round trip. Single-mode spectra are expected from smaller square-shaped micro-cavities.

Measurement of fiber-cladding diameter uniformity by use of whispering-gallery modes: nanometer resolution in diameter variations along millimeter to centimeter lengths.

Variations in fiber-cladding diameter on a nanometer scale were measured along millimeter to centimeter lengths by use of whispering-gallery modes (WGMs) in the elastic scattering of the fiber. The fiber was side coupled with a wavelength-tunable Gaussian beam. The scattered light was imaged approximately 1:1 onto a multichannel photodiode array detector. Based on the WGM wavelength shifts along the fiber, the taper of the fiber cladding's diameter was measured on a nanometer/millimeter scale. The fiber's surface roughness amplitude (in nanometers) and granular size ( approximately 100 microm) along centimeter-length fibers could also be revealed by use of higher- Q resonances.

Predictors of left ventricular outflow obstruction following single-stage repair of interrupted aortic arch and ventricular septal defect.

This study looked at echocardiographic predictors of left ventricular outflow obstruction after primary neonatal repair of interrupted aortic arch and ventricular septal defect. Results of this study indicate that the only significant independent predictor of left ventricular outflow obstruction is aortic valve diameter; all patients with an aortic valve diameter <4.5 mm (Z score <-5) subsequently developed obstruction, whereas patients with annuli >4.5 mm (Z score >-5) remained free from obstruction.

Factors associated with age at operation for children with congenital heart disease.

OBJECTIVE: Previous studies have shown that children with congenital heart disease (CHD) who live in nonurban areas or who do not have private insurance are at risk for delayed referral to a pediatric cardiologist. However, the effect of these factors on the age at which cardiac surgery is performed has not been evaluated. This study is designed to evaluate the factors that influence the age at which definitive surgical repair is performed. METHODS: Data on hospital discharges for 1995 and 1996 in California were obtained from the Office of Statewide Health Planning and Development database. Children <18 years who underwent surgical repair for atrial septal defect (ASD), ventricular septal defect (VSD), tetralogy of Fallot (TOF), or atrioventricular canal (AVC) were included in the study. Age at surgery was evaluated using type of CHD, gender, race, type of insurance, surgical centers, urban or rural home location, and distance between home and surgical center as independent variables. RESULTS: In 1995-1996, 666 children underwent ASD closure (mean age: 5.1 years; median: 4.0 years), 582 VSD closure (mean age: 2.8; median: 1.1 years), 394 TOF repair (mean age: 1.7; median:.9 years), and 177 AVC repair (mean age: 1.1; median:.6 years). Comparing median and mean age at surgery, we found: AVC

Consolidation behavior of an experimental, cross-linked polyalkyl ammonium polymer.

The effect of various factors (i.e., particle size, lubricant, moisture, and excipients) on the tableting properties of DMP 504 powder, an experimental, cross-linked polyalkyl ammonium polymer, was studied using an instrumented single-punch tablet press. The results indicate that plastic deformation is the primary consolidation mechanism for DMP 504. Lubrication of DMP 504 with magnesium stearate resulted in negative interaction in compactibility. The increase in tablet hardness with increase in water content of DMP 504 (up to 2.5%) could be attributed to the lubricating effect of water. Increasing the water content above the optimum moisture range (i.e., 2.5% to 4.0%) caused a drastic reduction in tablet crushing strength due to the hydrodynamic resistance. A mixture of DMP 504 with microcrystalline cellulose or starch led to a positive interaction with respect to compactibility. A deviation in tablet strength from the linear interpolated value did not correspond to a deviation in tablet thickness. The improved compactibility for the mixture of DMP 504 and microcrystalline cellulose or starch is not related directly to the facilitated densification.

Observations and calculations of light scattering from clusters of spheres.

Two-dimensional angular optical scattering (TAOS) patterns from clusters of polystyrene latex spheres are measured in the near-forward and near-backward directions. In both cases, the scattering pattern contains a rich and complicated structure that is the result of the interaction and interference of light among the primary particles. Calculations are made for aggregates that are similar to those generated experimentally and also demonstrate the rich structure in the scattering pattern. A comparison of the experimental and theoretical TAOS patterns gives good qualitative agreement.

Bubble contrast echocardiography in detecting pulmonary arteriovenous shunting in children with univentricular heart after cavopulmonary anastomosis.

OBJECTIVES: We sought to compare bubble contrast echocardiography and pulmonary angiography in detecting pulmonary arteriovenous malformation (PAVM) in children with cavopulmonary anastomosis (CPA), and to examine anatomic and physiologic variables associated with the development of PAVM. BACKGROUND: Development of PAVM in patients with CPA may cause profound cyanosis. Pulmonary arteriovenous malformation has been traditionally diagnosed by pulmonary angiography with reported incidence of 20% to 25% in patients with CPA. METHODS: Fourteen patients (age 1.1 to 12.6 years) with any forms of CPA and normal pulmonary venous drainage formed the study population. All patients underwent cardiac catheterization and pulmonary angiography. Bubble contrast echocardiographic studies were performed with injection of 10 ml of agitated saline solution into branch pulmonary arteries. Transthoracic echocardiograms using an apical view were performed to assess the appearance of bubble contrast in the systemic ventricles. We compared the results of pulmonary angiograms and contrast echocardiograms, and findings of contrast echocardiograms between lungs with hepatic venous blood flow and lungs without hepatic venous blood. RESULTS: Ten of the 14 patients (71%) had positive contrast echocardiographic studies, compared with three (21%) detected by pulmonary angiograms (p = 0.01). No difference was found in pulmonary artery pressure, transpulmonary gradient or presence of heterotaxy syndrome between patients with positive contrast echocardiographic studies and patients with negative studies. However, patients with positive contrast echocardiograms tended to have lower oxygen saturation (81%) and higher hemoglobin (16.4 g/dl) compared with patients with negative studies (88% and 14.7 g/dl, p = 0.10 and p = 0.18 respectively). Patients with Glenn shunt or unidirectional Fontan had higher incidence of PAVM (10/11) compared with patients with classic or lateral tunnel Fontan (0/3, p = 0.01). All 12 lungs with no perfusion of hepatic venous blood had positive contrast echocardiographic studies. Lungs with no hepatic venous blood flow were more likely to develop PAVM compared with lungs with hepatic venous blood flow (12/12 and 3/16 respectively, p < 0.01). CONCLUSIONS: Bubble contrast echocardiography is more sensitive in detecting PAVM compared with pulmonary angiography. The prevalence of PAVM in patients with CPA may be much higher than what had been reported previously. Lungs with no hepatic venous blood flow are more likely to develop PAVM than lungs with hepatic venous blood flow.