Publications by authors named "Hoang H Nguyen"

29 Publications

  • Page 1 of 1

Excitonic structure and charge separation in the heliobacterial reaction center probed by multispectral multidimensional spectroscopy.

Nat Commun 2021 05 14;12(1):2801. Epub 2021 May 14.

Department of Physics, University of Michigan, Ann Arbor, MI, USA.

Photochemical reaction centers are the engines that drive photosynthesis. The reaction center from heliobacteria (HbRC) has been proposed to most closely resemble the common ancestor of photosynthetic reaction centers, motivating a detailed understanding of its structure-function relationship. The recent elucidation of the HbRC crystal structure motivates advanced spectroscopic studies of its excitonic structure and charge separation mechanism. We perform multispectral two-dimensional electronic spectroscopy of the HbRC and corresponding numerical simulations, resolving the electronic structure and testing and refining recent excitonic models. Through extensive examination of the kinetic data by lifetime density analysis and global target analysis, we reveal that charge separation proceeds via a single pathway in which the distinct A chlorophyll a pigment is the primary electron acceptor. In addition, we find strong delocalization of the charge separation intermediate. Our findings have general implications for the understanding of photosynthetic charge separation mechanisms, and how they might be tuned to achieve different functional goals.
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http://dx.doi.org/10.1038/s41467-021-23060-9DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8121816PMC
May 2021

Feasibility of P wave Centric Ambulatory Electrocardiogram Monitoring in Infants and Young Children.

Pediatr Cardiol 2021 Jun 10;42(5):1126-1132. Epub 2021 Apr 10.

Department of Pediatrics, Rush University Medical Center, Chicago, IL, 60612, USA.

P wave centric ambulatory electrocardiographic (ECG) monitoring has emerged as an important tool aiding the diagnosis of arrhythmias. However, their efficacy and user experience in infants and young children are not well established. A retrospective study was performed to detail clinical and user experience of ECG monitoring using the Carnation Ambulatory Monitor (CAM) patch (Bardy Diagnostics Inc., Seattle, WA) in patients less than 10 kg. Additionally, 2 different monitor locations (over the sternum and horizontal over the left axilla) were assessed to address the optimal placement in these patients. A total of 33 CAM reports from 25 patients, aged 0 to15 months were included in the study. Mean patient age was 4.2 months ± 5.0 and mean weight was 5.3 kg ± 2.4. Thirty-six percent of patients (9/25) had known congenital heart disease. Indications for monitoring included: tachyarrhythmia (15/33, 45%), bradyarrhythmia (6/33, 18%), ectopic rhythm (9/33, 27%), cardiac tumor (1/33, 1%), and prolonged QT interval (1/33, 1%). All CAM reports showed clear, identifiable P waves which were diagnostic and lead to changes in medical management for 30% of patients (e.g., medication adjustments or discharge from cardiology care). We found the upright placement over the sternum performed better than the horizontal placement over the left axilla for small infants and children less than 10 kg. A P wave centric single-lead ECG monitor is helpful in providing accurate diagnostics tracings in infants and small children aiding in their clinical management.
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http://dx.doi.org/10.1007/s00246-021-02590-5DOI Listing
June 2021

Resting electrocardiographic differences in ventricular repolarization between children and young adults with congenital heart disease and those with a structurally normal heart are diminished by exercise.

Pacing Clin Electrophysiol 2021 Jun 19;44(6):1047-1053. Epub 2021 Apr 19.

Department of Pediatrics, Rush University Medical Center, Chicago, Illinois, USA.

Objective: Exercise-induced repolarization changes have not been systematically evaluated in children and young adults with congenital heart disease (CHD). We carried out this study to assess the QTc responses during exercise in children and young adults (≤ 21 years) with CHD with comparison to those with structurally normal hearts.

Methods: Baseline QRS duration, calculated baseline QTc, QTc at 4 min of recovery and delta QTc was measured in 360 exercise stress tests which were performed in 360 subjects (137 stress tests in patients with CHD [CHD group] and 223 stress tests in patients with structurally normal hearts). The effects of presence of CHD and potential confounders on primary outcome measure, change in QTc (delta QTc), and secondary outcome measures (QTc at baseline and QTc at 4 min of recovery) were determined using multiple linear regression analyses.

Results: The baseline QTc and the QTc at 4 min of recovery in the CHD group was longer than patients with structurally normal hearts (respective p values = .00 and .001). No significant difference was noted in delta QTc between the CHD and structurally normal heart groups.

Conclusions: While patients with CHD had a longer QRS duration and QTc interval at baseline than those with structurally normal hearts, these differences did not persist or augment with exercise.
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http://dx.doi.org/10.1111/pace.14241DOI Listing
June 2021

Prevalence of cardiac arrhythmias in cannabis use disorder related hospitalizations in teenagers from 2003 to 2016 in the United States.

Europace 2021 Mar 16. Epub 2021 Mar 16.

Department of Pediatrics, Division of Pediatric Cardiology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA.

Aims: Cannabis is an increasingly common recreational substance used by teenagers. However, there is limited data probing association of cardiac arrhythmias with marijuana use in this population.

Methods And Results: We provide prevalence trends, disease burden and healthcare utilization of cardiac arrhythmias associated with cannabis use disorder (CUD) in hospitalized teenagers (13-20 years) using a large national administrative database in the United States from 2003-2016. We used partial least square regression analysis for assessing trends in prevalence of cardiac arrhythmias and multiple logistic regression to elucidate independent predictors of arrhythmias associated with CUD. Among all CUD related hospitalizations (n = 876, 431), 0.5% had arrhythmias. Prevalence trends of arrhythmias among CUD increased six-fold during the study period (P < 0.001). CUD was more prevalent in males and older teens (both P < 0.001). There was a significant risk for mortality when CUD was associated with arrhythmia (7.4% vs. 0.1%, P < 0.001). While mean length-of-stay (LOS) was shorter (4.4 vs. 5.4 days, P < 0.001) for patients with CUD, they incurred three times higher mean hospitalization charges when compared to CUD patients without arrhythmia ($45 959 vs. $18 986, P < 0.001). Both LOS and hospitalization charges showed an uptrend during the study period (P < 0.001). Congenital heart disease, congestive heart failure, hypertension, and obesity independently predicted arrhythmias in CUD while other substance abuse did not change the risk of arrhythmia in CUD.

Conclusion: Arrhythmia burden is increasing among teenagers with CUD, and co-occurrence of arrhythmia and CUD worsens hospital outcomes.
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http://dx.doi.org/10.1093/europace/euab033DOI Listing
March 2021

Prevalence of structural birth defects among infants with Down syndrome, 2013-2017: A US population-based study.

Birth Defects Res 2021 01 21;113(2):189-202. Epub 2020 Dec 21.

Department of Pediatrics, Section of Hematology-Oncology, Baylor College of Medicine, Houston, Texas, USA.

Background: Down syndrome is the most common chromosomal disorder at birth and is often accompanied by structural birth defects. Current data on major structural defects in this population are limited.

Methods: States and territorial population-based surveillance programs submitted data on identified cases of Down syndrome and identified structural birth defects during 2013-2017. We estimated prevalence by program type and maternal and infant characteristics. Among programs with active case ascertainment, we estimated the prevalence of birth defects by organ system and for specific defects by maternal age (<35, ≥35) and infant sex.

Results: We identified 13,376 cases of Down syndrome. Prevalence among all programs was 12.7 per 10,000 live births. Among these children, 75% had at least one reported co-occurring birth defect diagnosis code. Among 6,210 cases identified by active programs, 66% had a cardiovascular defect with septal defects being the most common: atrial (32.5%), ventricular (20.6%), and atrioventricular (17.4%). Defect prevalence differed by infant sex more frequently than by maternal age. For example, atrioventricular septal defects were more common in female children (20.1% vs. 15.1%) while limb deficiencies were more prevalent in male children (0.4% vs. 0.1%).

Conclusions: Our study provides updated prevalence estimates for structural defects, including rare defects, among children with Down syndrome using one of the largest and most recent cohorts to date. These data may aid clinical care and surveillance.
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http://dx.doi.org/10.1002/bdr2.1854DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7978493PMC
January 2021

False Asystole Alarms Post-Temporary Pacemaker Placement Due to Pseudo-fusion.

Pediatr Cardiol 2021 Jan 28;42(1):215-218. Epub 2020 Nov 28.

Department of Pediatrics, Rush University Medical Center, Chicago, IL, 60612, USA.

An infant with congenital heart block and hemodynamically significant bradycardia underwent therapeutic temporary pacing wires placement. Post-operatively, frequent "asystole" alarms were observed on telemetry causing distress to both the family and the nursing staff. Investigation of these alarms showed that pacemaker malfunction led to monitor pseudo-malfunction. The alarms were alleviated with mindful setting of the pacemaker and telemetry monitor parameters. This case highlights the challenges of pacemaker placement and monitoring of very small infants in the intensive care setting. Awareness of these challenges would help in troubleshooting pacemaker and telemetry monitor issues.
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http://dx.doi.org/10.1007/s00246-020-02502-zDOI Listing
January 2021

Two-dimensional electronic Stark spectroscopy of a photosynthetic dimer.

J Chem Phys 2020 Oct;153(14):144203

Institute of Chemical Physics, Faculty of Physics, Vilnius University, Sauletekio 9-III, 10222 Vilnius, Lithuania.

Stark spectroscopy, which measures changes in the linear absorption of a sample in the presence of an external DC electric field, is a powerful experimental tool for probing the existence of charge-transfer (CT) states in photosynthetic systems. CT states often have small transition dipole moments, making them insensitive to other spectroscopic methods, but are particularly sensitive to Stark spectroscopy due to their large permanent dipole moment. In a previous study, we demonstrated a new experimental method, two-dimensional electronic Stark spectroscopy (2DESS), which combines two-dimensional electronic spectroscopy (2DES) and Stark spectroscopy. In order to understand how the presence of CT states manifest in 2DESS, here, we perform computational modeling and calculations of 2DESS as well as 2DES and Stark spectra, studying a photosynthetic dimer inspired by the photosystem II reaction center. We identify specific cases where qualitatively different sets of system parameters produce similar Stark and 2DES spectra but significantly different 2DESS spectra, showing the potential for 2DESS to aid in identifying CT states and their coupling to excitonic states.
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http://dx.doi.org/10.1063/5.0021529DOI Listing
October 2020

Influence of Prone Positioning on Electrocardiogram in a Patient With COVID-19.

JAMA Intern Med 2020 Nov;180(11):1521-1523

Rush University Medical Center, Chicago, Illinois.

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http://dx.doi.org/10.1001/jamainternmed.2020.3818DOI Listing
November 2020

Steroid-associated bradycardia in a newly diagnosed B precursor acute lymphoblastic leukemia patient with Holt-Oram syndrome.

Ann Pediatr Cardiol 2020 Jul-Sep;13(3):241-243. Epub 2020 Jun 2.

Department of Pediatrics, Rush University Medical Center, Chicago, IL, USA.

Holt-Oram syndrome (HOS) (OMIM#142900) is a rare condition with upper extremity malformations as well as structural and conduction cardiac anomalies. There are sparse reports in the literature documenting malignancy in association with HOS. We report a pediatric patient clinically diagnosed with HOS (missing thumbs bilaterally, atrial septal defect, ventricular septal defect, and first-degree heart block), who also developed B precursor acute lymphoblastic leukemia. During induction of chemotherapy with steroids, she developed profound bradycardia without clinical symptoms. The bradycardia resolved without intervention, but this case highlights the challenges of managing chemotherapy side effects in a patient with congenital heart disease. A literature review pertinent to the associated findings in the case is also presented.
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http://dx.doi.org/10.4103/apc.APC_87_19DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7437613PMC
June 2020

Magnesium Supplementation Shortens Hemodialysis-Associated Prolonged QT.

Cureus 2020 Jul 11;12(7):e9132. Epub 2020 Jul 11.

Pediatrics, University of Texas Southwestern Medical Center, Dallas, USA.

Hemodialysis affects myocardial depolarization and repolarization notably lengthening the QT interval. Prolonged QT, in turn, has been a reliable surrogate for higher risk of potentially lethal ventricular arrhythmias. We present an adolescent girl with end-stage kidney disease who consistently developed prolonged QT following hemodialysis sessions. Interestingly, her QT intervals were inversely correlated with her serum magnesium levels. Magnesium supplementation appeared to help reduce the QT prolongation after hemodialysis. Our case shows the potential utility of magnesium as a cardioprotective agent in hemodialysis patients. We recommend that patients undergoing hemodialysis receive frequent electrocardiograms and electrolytes monitoring for tailored electrolytes management to reduce the risk of developing potentially lethal cardiac arrhythmias.
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http://dx.doi.org/10.7759/cureus.9132DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7358902PMC
July 2020

Marked lateral ST-segment elevation with inferior ST-segment depression in an asymptomatic 12 year-old girl: A normal variant?

J Electrocardiol 2020 Jul - Aug;61:23-26. Epub 2020 May 18.

Center for Arrhythmia Care, Heart & Vascular Center, Pritzker School of Medicine of the University of Chicago, Chicago, IL, United States of America.

Significant ST-segment changes raise concern for myocardial ischemia, cardiomyopathy or myocardial inflammation and therefore, warrant an extensive and often invasive cardiovascular evaluation. We report a 12 year-old asymptomatic African-American girl with marked ST-segment elevation in leads I and aVL and ST-segment depression in inferior leads II, III and aVF. Extensive cardiovascular evaluation did not reveal any abnormality suggesting that these findings, which have previously not been reported, are likely benign, at least in this young girl.
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http://dx.doi.org/10.1016/j.jelectrocard.2020.05.011DOI Listing
June 2021

Complicated ventricular arrhythmia and hematologic myeloproliferative disorder in RIT1-associated Noonan syndrome: Expanding the phenotype and review of the literature.

Mol Genet Genomic Med 2020 07 12;8(7):e1253. Epub 2020 May 12.

Department of Pediatrics, Rush University Medical College, Chicago, IL, USA.

Background: Noonan syndrome is an autosomal dominant disorder secondary to RASopathies, which are caused by germ-line mutations in genes encoding components of the RAS mitogen-activated protein kinase pathway. RIT1 (OMIM *609591) was recently reported as a disease gene for Noonan syndrome.

Methods And Results: We present a patient with RIT1-associated Noonan syndrome, who in addition to the congenital heart defect, had monocytosis, myeloproliferative disorder, and accelerated idioventricular rhythm that was associated with severe hemodynamic instability. Noonan syndrome was suspected given the severe pulmonary stenosis, persistent monocytosis, and "left-shifted" complete blood counts without any evidence of an infectious process. Genetic testing revealed that the patient had a heterozygous c.221 C>G (pAla74Gly) mutation in the RIT1.

Conclusion: We report a case of neonatal Noonan syndrome associated with RIT1 mutation. The clinical suspicion for Noonan syndrome was based only on the congenital heart defect, persistent monocytosis, and myeloproliferative process as the child lacked all other hallmarks characteristics of Noonan syndrome. However, the patient had an unusually malignant ventricular dysrhythmia that lead to his demise. The case highlights the fact that despite its heterogeneous presentation, RIT1-associated Noonan syndrome can be extremely severe with poor outcome.
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http://dx.doi.org/10.1002/mgg3.1253DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7336743PMC
July 2020

Congenital right ventricular aneurysm with characteristics of a pseudoaneurysm.

Cardiol Young 2020 May 27;30(5):732-733. Epub 2020 Mar 27.

Pediatric Cardiology, Department of Pediatrics, Rush University Medical Center, Chicago, IL, USA.

We report a case of an isolated congenital right ventricular outpouching detected incidentally on foetal echocardiogram that was performed due to suspicion of CHD. Subsequent echocardiogram after birth revealed an aneurysm with features of a pseudoaneurysm having a thin and hypokinetic wall connected to the ventricle's cavity via a narrow neck. This pseudoaneurysm appears to be stable in size and of no clinical significance during the short-term follow-up.
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http://dx.doi.org/10.1017/S1047951120000633DOI Listing
May 2020

Intravenous Sotalol for the Treatment of Ventricular Dysrhythmias in an Infant on Extracorporeal Membrane Oxygenation.

Pediatr Cardiol 2020 Feb 29;41(2):418-422. Epub 2019 Oct 29.

Division of Cardiology, Department of Pediatrics, Rush University Medical College, 1753 W. Congress Pkwy., Pavilion 654, Chicago, IL, 60612, USA.

Sotalol is a class III anti-arrhythmic agent with beta receptor blocking properties. Intravenous (IV) sotalol may be useful to treat refractory atrial and ventricular arrhythmias. A report on the efficacy and safety of IV sotalol in an infant on extracorporeal membrane oxygenation (ECMO) and continuous renal replacement therapy (CRRT), who developed refractory ventricular arrhythmias following surgery for congenital heart disease. A 10-day old infant with severe pulmonary valve stenosis underwent surgical pulmonary valvectomy and enlargement of the main pulmonary artery. Post-operatively, the patient developed hemodynamically significant accelerated idioventricular rhythm which was not responsive to a combination of amiodarone, lidocaine, and procainamide leading to 2 cardiac arrest events and placement on ECMO. The amiodarone infusion was uptitrated to 20 mcg/kg/min, but episodes of the hemodynamically compromising arrhythmia continued. Amiodarone was discontinued and IV sotalol was initiated at 42 mg/m/day, divided to 3 doses, and administered every 8 h, which completely suppressed the arrhythmia. The initial sotalol dose was calculated based on a daily dose of 90 mg/m and reduced by an age-related factor as recommended by the FDA approved prescribing information. Subsequently, acute kidney injury requiring CRRT developed. The patient remained on IV sotalol for 3 weeks and then transitioned to oral sotalol. The oral dose was increased to 44 mg/m/day (3.5 mg every 8 h) to account for the difference in bioavailability between the IV and oral formulations. Serial sotalol levels during IV and PO therapy remained therapeutic on ECMO and CRRT. The patient maintained normal sinus rhythm on sotalol without adverse events. IV sotalol in the setting of ECMO and CRRT was safe and effective in controlling refractory hemodynamically compromising accelerated idioventricular rhythm unresponsive to amiodarone.
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http://dx.doi.org/10.1007/s00246-019-02225-wDOI Listing
February 2020

QT Prolongation After Minor Head Trauma in a Pediatric Patient.

Pediatr Cardiol 2020 Feb 10;41(2):414-417. Epub 2019 Oct 10.

Department of Pediatrics/Division of Cardiology, Rush University Medical College, Chicago, IL, USA.

We report a case of QTc prolongation associated with mild concussion in a pediatric patient. An 11-year-old male presented to the emergency department after sustaining a head injury during football practice. He complained of headache and blurry vision. Physical examination was within normal apart from an irregular heart rhythm. Electrocardiogram (ECG) showed normal sinus rhythm with QTc (Bazett formula) 460 ms. The patient was diagnosed with concussion and referred for cardiology follow-up of the QTc. ECG the next day showed QTc 462 ms (heart rate 105 bpm) supine and 494 ms after suddenly standing up (heart rate 120 bpm). Family history was negative for sudden cardiac events. Exercise stress testing 1 week later showed a baseline QTc 462 ms and 488 ms at 4 min into recovery. Holter monitoring showed evidence of increased parasympathetic activity manifested by marked sinus arrhythmia. Repeated ECG, exercise stress testing, and Holter monitoring 3 months later showed normalized QTc values. His concussion symptoms were resolved at the time of repeat testing. Mild head trauma/concussion could be associated with prolonged QTc and abnormal cardiac repolarization. While these changes seem to be self-limiting, they remain a possible substrate for malignant arrhythmias. Recognition of these changes would lead to appropriate reassurance and/or precautions in the acute setting, especially in at-risk populations such as long QT syndrome patients.
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http://dx.doi.org/10.1007/s00246-019-02213-0DOI Listing
February 2020

Dichotomous roles of in the establishment of atrioventricular conduction pathways in the human heart.

HeartRhythm Case Rep 2019 Feb 20;5(2):109-111. Epub 2018 Nov 20.

Department of Pediatrics, Washington University School of Medicine, St. Louis, Missouri.

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http://dx.doi.org/10.1016/j.hrcr.2018.11.005DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6379565PMC
February 2019

Determination of the Frequency of Right and Left Internal Mammary Artery Embolization in Single Ventricle Patients: A Two-Center Study.

Pediatr Cardiol 2018 Dec 13;39(8):1657-1662. Epub 2018 Aug 13.

Department of Pediatrics, Section of Pediatric Cardiology, Rush University Medical Center, 1653 W. Congress Parkway, Chicago, IL, 60612, USA.

Embolization of systemic to pulmonary artery collaterals to regulate pulmonary arterial flow or pressure of the cavopulmonary circulation in patients with single ventricle is a common practice. The relative incidence and impact of this practice on future interventions like coronary artery bypass grafting is poorly understood. This study aims to evaluate the frequency and implications of internal mammary artery (IMA) embolization in the single ventricle (SV) population. A retrospective chart review was performed of SV patients who underwent cardiac catheterization before and after Fontan procedure between February 2007 and 2017. Data were collected from two tertiary care centers in the Midwest. Of the 304 SV patients, 62 (20.4%) underwent embolization of one or more IMAs, whereas 242 (79.6%) did not. The rate of embolization of IMA was 40.5% in one center and 14.5% in the second center. Among patients who received IMA embolization, left internal mammary artery (LIMA) embolization was seen in 6 (9.7%) patients. Majority of patients underwent either right internal mammary artery (RIMA) embolization (n = 25; 40.3%) or RIMA and LIMA embolization (n = 27; 43.5%). IMA embolization in SV patients is common. Embolizing IMAs early in life will likely eliminate a valuable graft option for coronary artery bypass grafting should it be required in the future care of these patients. Multi-center, prospective, nation-wide studies are warranted to examine coronary artery disease in the SV population and true frequency of IMA embolization. Delineation of which IMAs were embolized is a necessary in surgical and cardiac intervention national data, such as Society of Thoracic Surgeons (STS) database. All measures should be taken to preserve IMAs patency, if deemed feasible and safe.
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http://dx.doi.org/10.1007/s00246-018-1946-0DOI Listing
December 2018

Acute Pediatric Colchicine Toxicity is Associated with Marked Bradydysrhythmias.

J Emerg Med 2018 09 29;55(3):e65-e69. Epub 2018 May 29.

Division of Cardiology, Department of Pediatrics, Rush University Medical College, Chicago, Illinois.

Background: Colchicine ingestion is rare but highly lethal. Patients usually die of multiorgan failure and cardiogenic shock. Colchicine is not only associated with depressed myocardial function but also with fatal heart rhythm disturbances, such as complete heart block, ventricular tachycardia, and asystole. While histologic changes of myocytes are well known, the mechanism by which colchicine affects cardiac impulse generation and conduction is not fully understood.

Case Report: We present a case of colchicine ingestion with sinus bradycardia, marked sinus arrhythmia, and first- and second-degree heart block. A 10-year-old previously healthy boy was brought to the emergency department for the sudden onset of dizziness, abdominal pain, and vomiting after ingesting his grandfather's colchicine and furosemide. His symptoms improved with ondansetron and intravenous normal saline. However, because of the colchicine ingestion, he was admitted to the pediatric intensive care unit for observation. He first developed PR prolongation (∼4-30 h postingestion) followed by marked sinus bradycardia and sinus arrhythmia along with second-degree heart block (∼48-60 hours postingestion). The minimum heart rate was 40 beats/min. Marked sinus arrhythmia was observed, suggesting an increase in parasympathetic activity. His heart rhythm improved initially with less sinus arrhythmia followed by resolution of heart block. He was discharged home without any sequelae. Holter monitoring 1 week after discharge showed normal heart rate variability for age. WHY SHOULD AN EMERGENCY PHYSICIAN BE AWARE OF THIS?: This case provides novel insights into how colchicine may affect the heart's electrophysiology. Colchicine may increase the parasympathetic tone enough to cause sinus bradycardia and different degrees of heart block.
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http://dx.doi.org/10.1016/j.jemermed.2018.03.004DOI Listing
September 2018

Normative Left Ventricular M-Mode Echocardiographic Values in Preterm Infants up to 2 kg.

J Am Soc Echocardiogr 2017 Aug 7;30(8):781-789.e4. Epub 2017 Jun 7.

Department of Pediatrics, Washington University School of Medicine, St. Louis, Missouri. Electronic address:

Background: There is a paucity of normative echocardiographic data in preterm infants. The objectives of this study were to (1) derive left ventricular (LV) M-mode reference values and (2) compare the performance of alternative methods of indexing LV dimensions and LV mass (LVM) in preterm infants. The authors propose that indexing LV measures to weight in preterm infants is a practical approach given the variability associated with tape-measure length measurement in infants.

Methods: In this retrospective study, LV M-mode echocardiographic measurements of end-diastolic interventricular septal thickness, end-diastolic LV posterior wall thickness, LV end-diastolic and end-systolic dimensions, LVM, and relative wall thickness were remeasured in 503 hospitalized preterm infants ≤2 kg (372 from a retrospective sample and 131 prospectively enrolled). Measures for all variables did not differ between retrospective and prospective samples, so results were pooled. LV dimensions and LVM indexed for weight, length, and body surface area sex-specific centile curves and corresponding Z scores were generated using Cole's lambda-mu-sigma method. Threshold limits (10th and 80th percentiles) were used to generate the normative range for relative wall thickness.

Results: Sex-specific centile curves using LVM, end-diastolic interventricular septal thickness, end-diastolic LV posterior wall thickness, LV end-diastolic dimension, and LV end-systolic dimension indexed to weight were similar to the curves generated using length and body surface area. The mean normal range for relative wall thickness was 0.33 (10th percentile, 0.26; 80th percentile, 0.38).

Conclusions: From this large cohort of preterm infants, LV M-mode dimension and LVM centile curves indexed to weight were developed as a practical method to assess LV morphology in preterm infants.
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http://dx.doi.org/10.1016/j.echo.2017.04.010DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5609837PMC
August 2017

Reveal LINQ Versus Reveal XT Implantable Loop Recorders: Intra- and Post-Procedural Comparison.

J Pediatr 2017 08 22;187:290-294. Epub 2017 May 22.

Division of Cardiology, Department of Pediatrics, Washington University in St. Louis School of Medicine, St. Louis, MO. Electronic address:

Objectives: To compare the procedure, recovery, hospitalization times, and costs along with patient/parent satisfaction after newer-generation cardiac implantable loop recorder (Reveal LINQ; Medtronic Inc, Minneapolis, Minnesota) and previous-generation implantable loop recorder (Reveal XT; Medtronic Inc).

Study Design: A prospective study of patients undergoing LINQ implantations between April 2014 and October 2015 was performed. Retrospective chart review of patients undergoing XT implantations was performed for comparison.

Results: Thirty-one patients received LINQ and 15 patients received XT. Indications included syncope/palpitations (28/46, 61%), history of arrhythmias (9/46, 20%), arrhythmia burden in congenital heart disease (5/46, 10%), and monitoring in channelopathies (4/46, 9%). The LINQ group underwent more conscious sedation procedures than the XT group (8/31 vs 0/15, P = .04) with shorter procedural time (9 vs 34 minutes, P <.001), room occupation time (38 vs 81 minutes, P <.001), recovery time (21 vs 67 minutes, P <.001), and total hospital time (214 vs 264 minutes, P = .046). The LINQ group also had shorter return to activity time (2 vs 5 days, P = 1). Three device erosions in the LINQ group required reintervention. The LINQ group had fewer body image issues than the XT group (1/26 vs 5/14, P = .01) with both groups scoring 5/5 overall patient/parent satisfaction score at follow-up. Both groups had comparable total direct hospital costs (US $5905 vs $5438, P = .8).

Conclusions: LINQ offers better procedural and recovery time compared with XT. LINQ implantations under conscious sedation reduce total hospitalization time.
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http://dx.doi.org/10.1016/j.jpeds.2017.04.057DOI Listing
August 2017

Force-Sensing Catheters During Pediatric Radiofrequency Ablation: The FEDERATION Study.

J Am Heart Assoc 2017 May 17;6(5). Epub 2017 May 17.

Division of Pediatric Cardiology, Washington University School of Medicine/St. Louis Children's Hospital, St. Louis, MO

Background: Based on data from studies of atrial fibrillation ablations, optimal parameters for the TactiCath (TC; St. Jude Medical, Inc) force-sensing ablation catheter are a contact force of 20 g and a force-time integral of 400 g·s for the creation of transmural lesions. We aimed to evaluate TC in pediatric and congenital heart disease patients undergoing ablation.

Methods And Results: Comprehensive chart and case reviews were performed from June 2015 to March 2016. Of the 102 patients undergoing electrophysiology study plus ablation, 58 (57%) underwent ablation initially with a force-sensing catheter. Patients had an average age of 14 (2.4-23) years and weight of 58 (18-195) kg with 15 patients having abnormal cardiac anatomy. Electrophysiology diagnoses for the +TC group included 30 accessory pathway-mediated tachycardia, 24 atrioventricular nodal reentrant tachycardia, and 7 other. Baseline generator settings included a power of 20 W, temperature of 40°, and 6 cc/min flow during lesion creation with 11 patients (19%) having alterations to parameters. Seventeen patients (30%) converted to an alternate ablation source. A total of 516 lesions were performed using the TC with a median contact force of 6 g, force-time integral of 149 g·s, and lesion size index of 3.3. Median-term follow-up demonstrated 5 (10%) recurrences with no acute or median-term complications.

Conclusions: TactiCath can be effectively employed in the treatment of pediatric patients with congenital heart disease with lower forces than previously described in the atrial fibrillation literature. Patients with atrioventricular nodal reentrant tachycardia or atrioventricular reciprocating tachycardia may not require transmural lesions and the TC may provide surrogate markers for success during slow pathway ablation.
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http://dx.doi.org/10.1161/JAHA.117.005772DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5524110PMC
May 2017

Chronic Low Dose Prostaglandin and Neonatal Heart Block.

Pediatr Cardiol 2017 Oct 16;38(7):1515-1518. Epub 2017 May 16.

Department of Pediatrics, Division of Cardiology, Rush University Medical College, 1653 W. Congress Pkwy., Pavilion 654, Chicago, IL, 60612, USA.

Long-term prostaglandin use is commonly associated with side effects such as cortical proliferation of the bones, hypertrophic pyloric stenosis, and soft tissue swelling of the extremities. We report a neonate with critical coarctation of the aorta, who developed second and third degree atrioventricular blocks associated with prolonged prostaglandin E1 (PGE1) infusion. Interestingly, these conduction blocks only occurred at low PGE1 dose. The rhythm disturbances resolved promptly with the discontinuation of PGE1 following surgical repair.
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http://dx.doi.org/10.1007/s00246-017-1633-6DOI Listing
October 2017

Tricuspid Atresia with Non-compaction: An Early Experience with Implications for Surgical Palliation.

Pediatr Cardiol 2017 Mar 10;38(3):495-505. Epub 2016 Dec 10.

Department of Pediatrics, Division of Cardiology, Washington University in St. Louis School of Medicine, 660 S. Euclid Ave., Campus Box 8116-NWT, St. Louis, 63110, MO, USA.

Left ventricle non-compaction (LVNC) has worse outcomes when associated with congenital heart defects (CHD). The co-occurrence and outcomes of LVNC with tricuspid atresia (TA) are not well described. Our study aims to determine the prevalence of LVNC with functionally single ventricle due to TA, and to describe the early outcomes of surgical palliation. A retrospective database search for patients (n = 167,566) and echocardiograms (n = 44,053) was performed in order to collect clinical, echocardiographic, and hemodynamic data of pediatric patients with TA and LVNC at St. Louis Children's Hospital, Missouri, USA, from January 1, 2008, to August 31, 2013. The prevalence of TA and LVNC was 0.015 and 0.08%, respectively. Eight patients with TA had LVNC (32%, group 1). Seventeen patients had only TA (68%, group 2). Five patients from group 1 and 8 patients from group 2 were surgically palliated with the Fontan procedure. They exhibited similar remodeling indices, and hemodynamics (median LV end-diastolic pressure ≤10 mmHg; median mean pulmonary artery pressure ≤15 mmHg) that allowed for completion of the Fontan procedure. All Fontan patients were in New York Heart Association class I after a 3-year (median) follow-up period. Our data show that TA with LVNC patients, who have acceptable cardiac remodeling indices, LV systolic function, and hemodynamics (LVEDP ≤ 10 mmHg, mean pulmonary artery pressure ≤ 15 mmHg) can have successful completion of the Fontan procedure and positive early outcomes.
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http://dx.doi.org/10.1007/s00246-016-1541-1DOI Listing
March 2017

Percutaneous Pulmonary Valve Implantation Alters Electrophysiologic Substrate.

J Am Heart Assoc 2016 09 30;5(10). Epub 2016 Sep 30.

Division of Cardiology, Department of Pediatrics, Washington University in St. Louis School of Medicine, St. Louis, MO

Background: Percutaneous pulmonary valve implantation (PPVI) is first-line therapy for some congenital heart disease patients with right ventricular outflow tract dysfunction. The hemodynamics improvements after PPVI are well documented, but little is known about its effects on the electrophysiologic substrate. The objective of this study is to assess the short- and medium-term electrophysiologic substrate changes and elucidate postprocedure arrhythmias.

Methods And Results: A retrospective chart review of patients undergoing PPVI from May 2010 to April 2015 was performed. A total of 106 patients underwent PPVI; most commonly these patients had tetralogy of Fallot (n=59, 55%) and pulmonary insufficiency (n=60, 57%). The median follow-up time was 28 months (7-63 months). Pre-PPVI, 25 patients (24%) had documented arrhythmias: nonsustained ventricular tachycardia (NSVT) (n=9, 8%), frequent premature ventricular contractions (PVCs) (n=6, 6%), and atrial fibrillation/flutter (AF/AFL) (n=10, 9%). Post-PPVI, arrhythmias resolved in 4 patients who had NSVT (44%) and 5 patients who had PVCs (83%). New arrhythmias were seen in 16 patients (15%): 7 NSVT, 8 PVCs, and 1 AF/AFL. There was resolution at medium-term follow-up in 6 (86%) patients with new-onset NSVT and 7 (88%) patients with new-onset PVCs. There was no difference in QRS duration pre-PPVI, post-PPVI, and at medium-term follow-up (P=0.6). The median corrected QT lengthened immediately post-PPVI but shortened significantly at midterm follow-up (P<0.01).

Conclusions: PPVI reduced the prevalence of NSVT. The majority of postimplant arrhythmias resolve by 6 months of follow-up.
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http://dx.doi.org/10.1161/JAHA.116.004325DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5121524PMC
September 2016

Radiation Exposure by Three-Dimensional Rotational Angiography (3DRA) During Trans-catheter Melody Pulmonary Valve Procedures (TMPV) in a Pediatric Cardiac Catheterization Laboratory.

Pediatr Cardiol 2016 Dec 25;37(8):1429-1435. Epub 2016 Jul 25.

Division of Cardiology, Department of Pediatrics, Washington University in St. Louis School of Medicine, 660 S. Euclid Ave., Campus Box 8116-NWT, St. Louis, MO, 63110-1093, USA.

This retrospective study aims to evaluate radiation exposure by three-dimensional rotational angiography (3DRA) during trans-catheter Melody pulmonary valve (TMPV) procedures. 3DRA has been reported to have added value in the management of complex congenital heart disease aiding in the performance of interventional procedures albeit with concerns of higher radiation exposure. We test the hypothesis that 3DRA does not cause additional radiation exposure during TMPV procedures. We analyzed all 81 TMPV procedures performed at St. Louis Children's Hospital, MO, USA, from January 1, 2011 to December 31, 2014. Dose-area product (DAP), DAP indexed to body weight (DAP/BW), fluoroscopy time (FT), and weight-fluoroscopy time product of each procedure were recorded. We reviewed each procedure's images to determine whether additional interventions were performed (e.g., pulmonary artery angioplasty or treatment of conduit pseudo-aneurysm). 3DRA was used in 36 % of the procedures. 3DRA group had a higher number of additional procedures performed. The 3DRA group did not differ from the non-3DRA group in DAP, DAP/BW, and weight-fluoroscopy time product. 3DRA does not cause greater radiation exposure during TMPV procedures.
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http://dx.doi.org/10.1007/s00246-016-1453-0DOI Listing
December 2016

Use of smartphone technology in cardiology.

Trends Cardiovasc Med 2016 May 19;26(4):376-86. Epub 2015 Nov 19.

Division of Pediatric Cardiology, Washington University School of Medicine-Saint Louis Children's Hospital, Saint Louis, MO. Electronic address:

Smartphone-based technologies along with broadband connectivity are changing the way modern cardiology is practiced. The ever broadening connectivity and increasing capabilities of smartphone-based technologies can better monitor, diagnose, and prevent cardiovascular diseases. Researchers can leverage the ubiquitous use of smartphone-based technologies and their constant stream of biometric data to establish large community-based clinical research studies. Patient engagement is enhanced with constant and on-demand access to physicians, daily self-monitoring, and expanding social networks. On the other hand, the exponential growth of smartphone-based technologies invariably disrupts the traditional healthcare model and leaves a vacuum in the infrastructure, medico-legal apparatus, and reimbursement systems that need to be addressed. In this review, we present a comprehensive discussion of the various applications utilizing smartphone-based technologies in cardiology.
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http://dx.doi.org/10.1016/j.tcm.2015.11.002DOI Listing
May 2016

SPEAR Trial: Smartphone Pediatric ElectrocARdiogram Trial.

PLoS One 2015 21;10(8):e0136256. Epub 2015 Aug 21.

Washington University in St. Louis School of Medicine, Department of Pediatrics/Division of Cardiology, St. Louis, Missouri, United States of America.

Objectives: Smartphone-enabled ECG devices have the potential to improve patient care by enabling remote ECG assessment of patients with potential and diagnosed arrhythmias. This prospective study aimed to assess the usefulness of pediatric ECG tracings generated by the AliveCor device (Oklahoma City, OK) and to assess user satisfaction.

Study Design: Enrolled pediatric patients with documented paroxysmal arrhythmia used the AliveCor device over a yearlong study period. Pediatric electrophysiologists reviewed all transmitted ECG tracings. Patient completed surveys were analyzed to assess user satisfaction.

Results: 35 patients were enrolled with the following diagnoses: supraventricular tachycardia (SVT, 57%), atrial fibrillation (AF, 11%), ectopic atrial tachycardia (EAT, 6%), atrial tachycardia (AT, 3%), and ventricular tachycardia (VT, 23%). A total of 238 tracings were received from 20 patients, 96% of which were of diagnostic quality for sinus rhythm, sinus tachycardia, SVT, and AF. 126 patient satisfaction surveys (64% from parents) were completed. 98% of the survey responses indicated that it was easy to obtain tracings, 93% found it easy to transmit the tracings, 98% showed added comfort in managing arrhythmia by having the device, and 93% showed interest in continued use of the device after the study period ended.

Conclusions: Smartphone-enabled ECG devices can generate tracings of diagnostic quality in children. User satisfaction was extremely positive. Use of the device to manage certain patients with AF and SVT showcases the future role of remote ECGs in the successful outpatient management of arrhythmias in children by potentially reducing Emergency Department visits and healthcare costs.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0136256PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4546652PMC
May 2016

Left aortic arch, right descending aorta, and right patent ductus arteriosus: precise depiction of a rare vascular ring with cardiac computed tomography.

Circulation 2015 Apr;131(15):e404-5

From the Division of Pediatric Cardiology (H.H.N., S.A.), Division of Diagnostic Radiology (E.S., T.H.), and Division of Cardiothoracic Surgery (P.M.), Washington University School of Medicine, St. Louis, MO.

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http://dx.doi.org/10.1161/CIRCULATIONAHA.114.012916DOI Listing
April 2015

A single misstep in cardiac development explains the co-occurrence of tetralogy of fallot and complete atrioventricular septal defect in Down syndrome.

J Pediatr 2014 Jul 8;165(1):194-6. Epub 2014 Apr 8.

Department of Pediatrics, Washington University School of Medicine, St. Louis, MO; Department of Genetics, Washington University School of Medicine, St. Louis, MO. Electronic address:

Tetralogy of Fallot and a complete atrioventricular septal defect are thought to arise by distinct mechanisms, yet their co-occurrence is a recognized association. Analysis of the prevalence of co-occurrence in Down syndrome suggests a common developmental basis. Trisomy 21 may perturb cardiac progenitor cells before they enter the heart tube.
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http://dx.doi.org/10.1016/j.jpeds.2014.02.065DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4074567PMC
July 2014
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