Echocardiography as a Simple Initial Tool to Assess Right Ventricular Dimensions in Patients with Repaired Tetralogy of Fallot before Undergoing Pulmonary Valve Replacement: Comparison with Cardiovascular Magnetic Resonance Imaging

Objective: Accurate assessment of the right ventricle (RV) is essential in patients with repaired tetralogy of Fallot (TOF). We proposed a simple echocardiographic method to assess the RV dimensions and evaluated the relationship between linear echocardiographic measures of the RV and RV volumes obtained by cardiovascular magnetic resonance imaging (CMR). Methods: A total of 45 patients (27.4 ± 11.2 years; 40% male) with repaired TOF underwent CMR and echocardiography. Using echocardiography, RV dimensions were assessed from the parasternal short‐axis view using the longest RV internal diameter perpendicular to the mid‐interventricular septum. Significant RV dilatation was defined as an RV end‐diastolic volume index >160 mL/m² on CMR. Results: There were significant correlations between RV dimensions determined by echocardiography and the pulmonary regurgitation fraction, RV size, and function determined by CMR. The cutoff values of echocardiographic RV outflow tract (RVOT), end‐systolic and end‐diastolic dimension indices, and the combination of RVOT and end‐diastolic dimension indices to determine significant RV dilatation were 19.0, 19.4, 24.5, and 45.2 mm/m², respectively. The positive and negative predictive values for significant RV dilatation were 89.7% and 68.8% with RVOT diameter index ≥19.0 mm/m², 85.0% and 52.4% with RV end‐systolic dimension index ≥19.4 mm/m², 87.5% and 64.7% with RV end‐diastolic dimension index ≥24.5 mm/m², and 92.3% and 80.0% with the combination of RVOT and end‐diastolic dimension indices ≥45.2 mm/m², respectively. Conclusion: Echocardiography can be used to assess RV size in patients with repaired TOF with acceptable correlations with CMR as the reference standard.     

Organic acid disorders detected by urine organic acid analysis: twelve cases in Thailand over three-year experience

BACKGROUND: Disorders of organic acid (OA) metabolism are generally detected by qualitative analysis of urine organic acids by gas chromatography/mass spectrometry (GC/MS) which was well established in developed countries since 1980s. Confirmation of the diagnosis of organic acid disorders by OA analysis, enzyme analysis and molecular study is a difficult task in developing countries. METHODS: During 2001-2004, we had analysed 442 urine samples in 365 patients and identified 12 cases of organic acid disorders. RESULTS: We identified the following disorders: alkaptonuria (ALK)=1, isovaleric acidemia (IVA)=3, propionic acidemia (PA)=2, methylmalonic acidemia (MMA)=3, glutaric aciduria, type I (GA-I)=1, multiple carboxylase deficiency (MCD)=1, and glutaric acidemia, type II (GA-II)=1. CONCLUSIONS: OA disorders had never been diagnosed in Thailand before, until GC/MS technology was introduced to Thailand in 2001. Urine OA analysis also provided a diagnostic clue to other inborn errors of metabolism including amino acid disorders, urea cycle disorders, disorders of carbohydrate metabolism, and mitochondrial fatty acid oxidation disorders. Since then, we were able to diagnose numerous disorders, which led to prompt treatment and better outcome in our patients.     

Improvement of Skills in Cardiopulmonary Resuscitation of Pediatric Residents by Recorded Video Feedbacks

Objective

To evaluate the pediatric residents’ cardiopulmonary resuscitation (CPR) skills, and their improvements after recorded video feedbacks.

Methods

Pediatric residents from a university hospital were enrolled. The authors surveyed the level of pediatric resuscitation skill confidence by a questionnaire. Eight psychomotor skills were evaluated individually, including airway, bag-mask ventilation, pulse check, prompt starting and technique of chest compression, high quality CPR, tracheal intubation, intraosseous, and defibrillation. The mock code skills were also evaluated as a team using a high-fidelity mannequin simulator. All the participants attended a concise Pediatric Advanced Life Support (PALS) lecture, and received video-recorded feedback for one hour. They were re-evaluated 6 wk later in the same manner.

Results

Thirty-eight residents were enrolled. All the participants had a moderate to high level of confidence in their CPR skills. Over 50 % of participants had passed psychomotor skills, except the bag-mask ventilation and intraosseous skills. There was poor correlation between their confidence and passing the psychomotor skills test. After course feedback, the percentage of high quality CPR skill in the second course test was significantly improved (46 % to 92 %, p = 0.008).

Conclusions

The pediatric resuscitation course should still remain in the pediatric resident curriculum and should be re-evaluated frequently. Video-recorded feedback on the pitfalls during individual CPR skills and mock code case scenarios could improve short-term psychomotor CPR skills and lead to higher quality CPR performance.

     

High protein diet mimics hypertyrosinemia in newborn infants

Tyrosinemia resulting from administration of protein-dense infant diets was detected by newborn screening in two infants. Change of formula resulted in rapid resolution of the hypertyrosinemia. These cases identify nonstandard infant diets as a benign and reversible cause of tyrosinemia and a potential cause of positive newborn phenylketonuria screening.     

The effect of prenatal nicotine exposure on PDGFR-mediated anti-apoptotic mechanism in the caudal brainstem of developing rat

Maternal cigarette smoking is a major risk factor for sudden infant death syndrome (SIDS); however, the mechanism underlying this association is currently unknown. Prenatal nicotine exposure is accompanied by a decrease in the magnitude of hypoxic ventilatory depression, the component of hypoxic ventilatory response that activates the PDGF-β receptor (PDGFR) and its downstream anti-apoptotic cascade in the caudal brainstem (CB) of developing rats. In this study, we evaluated the effect of prenatal nicotine exposure on PDGFR activation and the subsequent activation of downstream anti-apoptotic processes through the Akt/BAD pathway. The 5-day timed-pregnant Sprague–Dawley rats underwent surgical implantation of an osmotic pump containing either normal saline (control) or a solution of nicotine tartrate. The CB was harvested from 5-day-old rat pups (n = 8–10 for each time point) in each group after exposure to normoxia or hypoxic challenges with 10% O₂ for 5, 15, 30, 60 or 120 min. Immunoprecipitation and immunoblots of CB lysates revealed phosphorylation of PDGFR, Akt and BAD-136 during hypoxia in control pups. Prenatal nicotine exposure was associated with attenuation of these responses at all time points. Analysis of an early apoptotic marker in the CB revealed that activation of cleaved caspase-3 occurred only at 120 min of hypoxic exposure in the control. Prenatal nicotine exposure accelerated this response, causing early activation at 30 and 60 min. We conclude that prenatal nicotine exposure attenuates the phosphorylation of PDGFR, Akt and Bad-136 during hypoxia in the CB of developing rats. This modulation of anti-apoptotic cascades accelerates activation of the early apoptotic marker. We speculate that prenatal nicotine exposure affects apoptosis in the CB of developing animals and may increase the vulnerability of neural cells in the respiratory control area, a process that may underlie the association between maternal smoking and SIDS.     

Mutation spectrum of and founder effects affecting the PTS gene in East Asian populations

The enzyme 6-pyruvoyl-tetrahydropterin synthase (PTPS, gene symbol: PTS) is involved in the second step of the de novo biosynthesis of tetrahydrobiopterin (BH4), which is a vital cofactor of nitric oxide synthases and three types of aromatic amino acid hydroxylases; the latter are important enzymes in the production of neurotransmitters. We conducted a study of PTS mutations in East Asia, including Taiwan, Mainland China, Japan, South Korea, the Philippines, Thailand and Malaysia. A total of 43 mutations were identified, comprising 22 previously reported mutations and 21 new discovered mutations. Among these, the c.155A>G, c.259C>T, c. 272A>G, c.286G>A and c.84-291A>G mutations were the most common PTS mutations in East Asia, while the c.58T>C and c.243G>A mutations were, respectively, specific to Filipinos and Japanese originating from Okinawa. Further studies demonstrated that each of the mutations listed above was in linkage disequilibrium to a specific allele of polymorphic microsatellite marker, D11S1347. These results suggest the presence of founder effects that have affected these frequent mutations in East Asia populations. In this context, D11S1347 should become one of the most reliable polymorphic markers for use in prenatal diagnosis among PTPS deficient families, especially where mutations are yet to be identified.