CHD Electophysiology Featured Articles of April 2015

1. Breath Holding Spells in Children with Long QT Syndrome.

Robinson JA, Bos JM, Etheridge SP, Ackerman MJ.

Congenit Heart Dis. 2015 Apr 27. doi: 10.1111/chd.12262. [Epub ahead of print]

PMID: 25916402

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cohen picComment from Dr. Mitchell Cohen (Phoenix), section editor of Congenital Heart Electrophysiology Journal Watch: With combined data from Primary Children’s Hospital and the Mayo Clinic, Robinson and colleagues performed a retrospective review of 115 children diagnosed under 5 years of age with LQTS. As part of training to become a pediatric cardiologist, we all took care of children with breath holding spells as part of our general pediatric residency. On systems review, 5/115 (4.3%) of children with LQT had breath-holding spells. The mean QTc for these 5 patients was 492±14 msec and all had LQT1 (accounted for ≈ 10% of the LQT1 patients within the cohort). Although the association between LQT1 and breath-holding spells was identified in the series, it is important to note that the prevalence of breath-holding spells was identical to that of the general population. The etiology of breath holding spells remains unclear and is likely multi-factorial with a neurologic, autonomic, metabolic, and cardiorespiratory perturbations as causative. Although all 5 patients had an LQT1 genotype, the causative mutations were without a common variant. Although his study did not establish a clear relationship between breath holding spells and LQT, any evaluation of the child with a “spell” should always have LQT in the differential diagnosis.


2. The Association between Peri-Operative Dexmedetomidine and Arrhythmias after Surgery for Congenital Heart Disease.

Shuplock JM, Smith AH, Owen J, Van Driest SL, Marshall M, Saville B, Xu M, Radbill AE, Fish FA, Kannankeril PJ.

Circ Arrhythm Electrophysiol. 2015 Apr 15. pii: CIRCEP.114.002301. [Epub ahead of print]

PMID: 25878324

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Comment from Dr. Mitchell Cohen (Phoenix), section editor of Congenital Heart Electrophysiology Journal Watch: Dexmedetomidine is a selective alpha-2 adrenergic agonist used frequently following cardiac surgical procedures. Although dexmedetomidine is a peripheral parasympathomimetic it is also a central sympatholytic and decreases heart rate and blood pressure. In the EP laboratory, dexmedetomidine has been shown to decrease sinus node automaticity and alter AV nodal conduction. Dexmedetomidine has been used in the treatment of post-operative junctional ectopic tachycardia. It should not come as a surprise that a potential side effect of dexmedetomidine is bradyarrhythmias. Dr. Shuplock and colleagues from Vanderbilt compared 468 subjects dexmedetomidine to 1,125 subjects who did not receive dexmedetomidine. This is an excellent study and establishing a propensity score matching the patient receiving dexmedetomidine to a control patient along the lines of confounding variables enhanced the quality of this study. This approach significantly reduces the bias associated with such variables. Arrhythmia analysis outcome identified no difference in the post-operative tachyarrhythmias, within the first4 post-op days, between two groups after adjusting for the confounding variables. However, there were increased odds of developing bradyarrhythmias that required treatment in the dexmedetomidine group. Although not all patients developing such bradyarrhythmias required intervention, it does reiterate to the practitioner caution when using dexmedetomidine. This is even truer in those individuals with an underlying AV nodal conduction disorder or disturbance in sinus node function. This study, however, did not address dexmedetomidine as a treatment for tachyarrhythmias. Dexmedetomidine still likely has a role in the treatment of certain supraventricular arrhythmias. Ongoing research in this area is needed. Additionally this study only compared patients receiving dexmedetomidine upon returning form the operating room. It did not address the addition of dexmedetomidine during the CVICU stay. A future prospective study is warranted in the pediatric cardiac population receiving dexmedetomidine.


3. Oral rehydration salts: an effective choice for the treatment of children with vasovagal syncope.

Chu W, Wang C, Wu L, Lin P, Li F, Zou R.

Pediatr Cardiol. 2015 Apr;36(4):867-72. doi: 10.1007/s00246-015-1097-5. Epub 2015 Jan 11.

PMID: 25577227

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Comment from Dr. Mitchell Cohen (Phoenix), section editor of Congenital Heart Electrophysiology Journal Watch: Dr. Chu and colleagues from Hunan China evaluated 166 consecutive children with recurrent syncope and a documented positive tilt table test. The patients were randomized in a 1:1 fashion to head-up tilt table testing along with oral rehydration salts (Group I: 87 patients) versus conventional therapy only (Group II: 79 patients). All patients were 7-17 years of age and as part of secondary analysis were further subdivided into those < 12 years and those > 12 years of age. Patients were prospectively followed for 6 months. In Group I syncope did not reoccur in 56% and was lessened in 39%. In the conventionally treated group (II), syncope did not reoccur in 39% and was reduced in 47% of patients. While most pediatric cardiologists caring for children and adolescents with syncope view it as a somewhat benign condition, it has emerged as a disabling condition in many school-aged children. It has resulted in increased school absenteeism and decreased quality of life The oral rehydration salt mixture used in this study was mixed with 500 ml of water and was an admixture of glucose, NaCl, KCl, and NaHCO3. In comparison to many other studies previously evaluating adolescent syncope, which have strictly used NaCl, this admixture in this study proved beneficial as a non-pharmacologic treatment in the armamentarium of vasodepressor syncope. Additional prospective studies, including a cross-over period may be warranted.


4. Current practices in the monitoring of cardiac rhythm devices in pediatrics and congenital heart disease.

Boyer SL, Silka MJ, Bar-Cohen Y.

Pediatr Cardiol. 2015 Apr;36(4):821-6. doi: 10.1007/s00246-014-1090-4. Epub 2014 Dec 20.

PMID: 25527229

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Comment from Dr. Mitchell Cohen (Phoenix), section editor of Congenital Heart Electrophysiology Journal Watch: This study was a survey of members within the Pediatric and Congenital Electrophysiology Society (PACES) to identify current practices regarding use and timing of in-office pacemaker checks and remote interrogation monitoring. A total of 106 PACES members responded to the 10-question survey. Currently guidelines exist for the timing of cardiac rhythm devices and pediatric electrophysiologists generally follow those guidelines. This survey confirmed that hypothesis. The vast majority of pediatric electrophysiologists have moved towards using remote monitoring as opposed to the more traditional trans-telephonic transmission (TTM), which generally provide little information on events and true lead integrity. 87% of the respondents use remote monitoring quarterly. 32% of those that use remote monitoring believe it has reduced in-person evaluations. This is in contradistinction to the survey that found TTM only reduced in-office visits 21% of the time. While it s reassuring that the vast majority of pediatric electrophysiologists have adopted this newer technology it remains unclear as to what is the exact timing needed for most pediatric patients. After all, pediatric patients are subjected to a higher proclivity for lead injury secondary to activity and somatic growth. There is also more rapid battery depletion, as kids are more active. Lastly, from a societal standpoint, if home monitoring truly reduces in-office visits, the burden is less as the child does not have to miss school and a parent often does not have to miss a day at work. Home monitoring should absolutely be used for all children and adolescents with pacemakers and ICDs. The frequency potentially should be individualized but quality metrics should be deployed to answer some of these questions.


5. Automated external defibrillator rescues among children with diagnosed and treated long QT syndrome.

Pundi KN, Bos JM, Cannon BC, Ackerman MJ.

Heart Rhythm. 2015 Apr;12(4):776-81. doi: 10.1016/j.hrthm.2015.01.002. Epub 2015 Jan 7.

PMID: 25576780

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Comment from Dr. Mitchell Cohen (Phoenix), section editor of Congenital Heart Electrophysiology Journal Watch: Dr. Pundi and the group from the Mayo Clinic performed a retrospective analysis of 291 children diagnosed with LQT but who did not have an ICD implanted to ascertain use of an AED rescue over a mean follow-up of 6 years from the time of diagnosis. Out of the 291 children with LQT and no ICD, three had a life-threatening event and were rescued by bystander AED. The first AED occurred in an LQT 1 18 month-old boy during exercise. In review of his history he was profoundly high-risk having already had documented torsades on beta-blockers and the family chose left cardiac sympathetic denervation over an ICD. The parents following that event with document torsades again used his personal AED. The 2nd patient was a 14 year-old boy with LQT2 with a QTc > 550 msec. The 3rd patient was probably the greatest  surprise and one who most clinicians would have deemed not to be at high-risk: a 17 year-old female with LQT3 who was on mexilitine. Although the prevalence of AED use in those children diagnosed with LQT who do not have an ICD is exceedingly low and at least two of these patients were very high risk and may have been considered for an ICD, the AEDs either personal or professional worked in these three cases and all patients went on to receiving a permanent ICD. This single center has as its recommendation that all families have an AED. While there are financial considerations to be considered in having a personal AED, it remains a worthwhile goal. Future studies should address the barriers to having a personal AED and the ongoing limitations in not having greater AEDs in public places.


6. Detection of long QT syndrome in the community.

Skinner JR, Van Hare GF.

Heart Rhythm. 2015 Apr 17. pii: S1547-5271(15)00487-7. doi: 10.1016/j.hrthm.2015.04.020. [Epub ahead of print] No abstract available.

PMID: 25896012

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Comment from Dr. Mitchell Cohen (Phoenix), section editor of Congenital Heart Electrophysiology Journal Watch: In a response to a series of articles regarding screening of LQT in the community and amongst neonates, Dr. Skinner from New Zealand and Dr. Van Hare from St. Louis have recommended that screening efforts should focus on a more aggressive policy of detection of probands, cardiac genetic screening of family members, and concerted efforts amongst pediatric electrophysiologists and geneticists to establish a clinical registry. Their contention is that efforts focused on education at the provider level should help facilitate such goals.
7. Treatment of supraventricular tachycardia in infants: Analysis of a large multicenter database.

Chu PY, Hill KD, Clark RH, Brian Smith P, Hornik CP.

Early Hum Dev. 2015 Apr 28;91(6):345-350. doi: 10.1016/j.earlhumdev.2015.04.001. [Epub ahead of print]

PMID: 25933212

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Comment from Dr. Mitchell Cohen (Phoenix), section editor of Congenital Heart Electrophysiology Journal Watch: Chu and colleagues from the Duke Clinical Research Institute in combination with a large neonatal database of nearly 350 NICUs as part of Pediatrix Medical Group reviewed a large cohort of patients with neonatal SVT. Between 1998-2012, out of nearly 900,000 babies, 2,848 infants were diagnosed with SVT. Of this large cohort, 13% had congenital heart disease. The median postnatal age at diagnosis of SVT was 2 days and 66% of the study cohort had their first bout of SVT within 7days of age. Digoxin had been the most frequently used secondary prevention medication up until 2011 when beta-blockers became the most commonly used secondary agent. However, significant practice variation was typical. In both the CHD and non-CHD cohorts, 13% had clinical recurrences often necessitating multiple anti-arrhythmics. Combination Digoxin and beta-blockers were was the combination used in over 60% of babies with clinical recurrences. This is a retrospective study and as such the usual limitations are applicable. Future studies are certainly warranted and careful delineation of the types of tachycardias such as short and long RP SVT, automatic tachycardia versus reentrant tachycardias will better delineate a reasonable treatment strategy. The authors should be commended for a review of a large database and hopefully this study will initiate future studies.


8. A pilot study of a mindfulness based stress reduction program in adolescents with implantable cardioverter defibrillators or pacemakers.

Freedenberg VA, Thomas SA, Friedmann E.

Pediatr Cardiol. 2015 Apr;36(4):786-95. doi: 10.1007/s00246-014-1081-5. Epub 2014 Dec 12.

PMID: 25519914

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Comment from Dr. Mitchell Cohen (Phoenix), section editor of Congenital Heart Electrophysiology Journal Watch: This is an absolutely fantastic study that should really come as no surprise to pediatric cardiologist who cares for children with implantable devices. While we spend a great deal of time discussing the reason that a pacemaker or ICD is required and the procedure that the adolescent is about to undergo, it is really the after effects once the device is implanted that is starting to generate many questions. As pediatric electrophysiologists we are starting to gather better information to help us decide which channelopathy patient or complex CHD patient should undergo device implantation, however, we are less adroit at dealing with the psychosocial issues that accompany the implantation. We also know that patients, especially ICD recipients, are prone to anxiety, depression, and coping disorders following device implant which can be further worsened if inappropriate shocks occur. In a very well designed prospective study, albeit limited 10-person study, Vicki Freedenberg has shown that with a structured six-session “mindfulness based stress reduction program” the level of anxiety, depression, and coping mechanisms may improve. Larger studies are clearly warranted that not only involve more patients, patients of different ages, patients with different devices, optimal timing of such intervention, consideration for family intervention, and ongoing follow-up.  A larger prospective pre-device intervention study should be considered. With increased survival of patients with CHD into adulthood, increased genetic cascade screening for potential malignant channelopathies all likely generator increased numbers of patients receiving devices for primary prevention. We as a pediatric EP community should not only be prospective but also prescriptive for such psychosocial therapies. Cardiologists are likely inadequate at providing such psychosocial interventions. However, if ancillary psychology or psychiatry resources are inadequate, at least some training for cardiologists would serve as a starting point where other resources may be scarce. At the very least pediatric electrophysiologists, per this study, need to be aware of the prevalence of anxiety and depression amongst adolescents with implantable devices.


9. Frequency and Severity of Hypoglycemia in Children with Beta-Blocker Treated Long QT Syndrome.

Poterucha JT, Bos JM, Cannon BC, Ackerman MJ.

Heart Rhythm. 2015 Apr 27. pii: S1547-5271(15)00544-5. doi: 10.1016/j.hrthm.2015.04.034. [Epub ahead of print]

PMID: 25929701

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Comment from Dr. Mitchell Cohen (Phoenix), section editor of Congenital Heart Electrophysiology Journal Watch: The majority of children with LQT are treated with beta-blockers and beta-blockers are very effective, especially in LQT1. However, one of the known side effects of beta-blockers is that of hypoglycemia. Patients with hypoglycemia may present with a seizure further confusing the clinician caring for the patient with LQT who is always cognizant of life-threatening ventricular arrhythmias. Hypoglycemia is further more problematic in neonates in small infants who are less communicative and adolescents who may take their medicine but “skip” meals. In one of the largest retrospective studies evaluating this topic, the group from the Mayo Clinic evaluated 9 children with LQT who developed 13 episodes out of an LQT population of 383 children with clinically/genetically diagnosed LQT. This resulted in a 0.005 events per 100 treatment years. The majority presented with seizures (n=6) however, others presented with hypotonia, sleepiness, and 1 was found unresponsive. All patients recovered without significant neurologic sequelae. In all patients, decreased caloric intake was noted prior to the hypoglycemic event. Physicians prescribing beta-blockers in LQT patients must be absolutely cognizant of this side effect and educate mid-level providers or cardiology fellows who may be fielding such phone calls from parents in the after hours.


10. Brugada syndrome: clinical and genetic findings.

Sarquella-Brugada G, Campuzano O, Arbelo E, Brugada J, Brugada R.

Genet Med. 2015 Apr 23. doi: 10.1038/gim.2015.35. [Epub ahead of print] Review.

PMID: 25905440

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Comment from Dr. Mitchell Cohen (Phoenix), section editor of Congenital Heart Electrophysiology Journal Watch: This is an excellent review article by the Brugada brothers on the genetics, clinical presentation, and risk stratification for this syndrome. Awareness of fever prevention is critically important in this syndrome and all pediatric cardiologists should be aware of not only the pathophysiology, but common circumstances that can turn a stable condition into a malignant pro-arrhythmic condition.


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