Christine A. Walsh

Syncope in childhood

The records of 108 children, ages 2 to 19 years (mean age 11.3 years), who were referred to the pediatric neurology and pediatric cardiology clinics for syncope, were reviewed. Sixty-six cases were identified retrospectively, and 42 prospectively. Syncope was defined as transient and complete loss of consciousness with no etiology determined at the time of presentation. The mean follow-up was 2.0 years. In 27 cases (25%), an etiology for syncope was found, including migraines in 12 cases (11%), seizures in 9 cases (8%), and cardiac arrhythmias in 6 cases (6%). All other cases were classified as vasovagal (neurocardiogenic). The past medical history, family history, clinical features of each syncopal episode, and diagnostic tests of each subject were correlated to final diagnosis. No clinical or historical features reliably distinguished children with vasovagal syncope from those with other etiologies. Children referred for the evaluation of syncope have a significant incidence of serious but treatable disorders, which should be actively sought.

Challenges of genetic testing in adolescents with cardiac arrhythmia syndromes

The ability to sequence individual genomes is leading to the identification of an increasing number of genetic risk factors for serious diseases. Knowledge of these risk factors can often provide significant medical and psychological benefit, but also raises complex ethical and social issues. This paper focuses on one area of rapid progress: the identification of mutations causing long QT syndrome and other cardiac channel disorders, which can explain some previously unexplained deaths in infants (SIDS) and children and adults (SUDS) and prevent others from occurring. This genetic knowledge, discovered posthumously in many cases, has implications for clinical care for surviving family members who might carry the same mutations. The information obtained from genetic testing, in the context of personal and family history, can guide individually tailored interventions that reduce risk and save lives. At the same time, obtaining and disclosing genetic information raises difficult issues about confidentiality and decision making within families. We draw on the experience of the Montefiore-Einstein Center for Cardiogenetics, which has played a leading role in the genetic diagnosis and clinical management of cardiac channel diseases, to explore some of the challenging ethical questions arising in affected families with adolescent children. We focus on the related issues of (1) family confidentiality, privacy and disclosure and (2) adolescent decision making about genetic risk, and argue for the value of interdisciplinary dialogue with affected families in resolving these issues.

The use of levo-carnitine in children with renal disease: a review and a call for future studies

Carnitine is an amino acid derivative that has a key role in the regulation of fatty acid metabolism and ATP formation. Carnitine deficiency has been described in various conditions, including chronic kidney disease (CKD) and end stage renal disease (ESRD). The deficiency of this micronutrient is postulated to lead to adverse effects across multiple organ systems. There is a paucity of information on carnitine deficiency and its effects in the pediatric CKD and ESRD populations. Currently, there is no evidence supporting the routine use of carnitine supplementation in children with ESRD. In this article, we review the pathophysiology, pharmacokinetics and the potential effects of levo-carnitine supplementation with a focus on the pediatric CKD and ESRD populations. Finally, potential future directions of research are discussed.

Disclosing Genetic Information to Family Members About Inherited Cardiac Arrhythmias: An Obligation or a Choice?

Inherited cardiac arrhythmias such as long QT syndrome and Brugada syndrome, present clinical as well as ethical, legal, and social challenges. Many individuals who carry a deleterious mutation are largely asymptomatic and therefore may not be diagnosed until after the occurrence of a personal or family member’s cardiac event. The familial nature of inherited genetic information raises numerous ethical, legal, and social issues regarding the sharing of genetic information, particularly when an individual found to carry a deleterious mutation refuses to disclose his or her results to at-risk family members who could benefit from life-saving treatments. This qualitative study sought to understand the experiences with genetic testing for individuals (n = 50) with a personal or family history of cardiac events or sudden death. Unstructured in-person focus groups or interviews were conducted for each participant in the study. The recordings of these interviews were transcribed verbatim and subsequently analyzed and coded. Participants’ comments regarding sharing of genetic information centered around four main themes: (1) motivation to disclose; (2) extent of disclosure; (3) effect of disclosure on family dynamics; and (4) reasons for not sharing genetic information. The majority of individuals believed that affected individuals are obligated to disclose genetic information to family members. In the era of personalized medicine, the disclosure of genetic information provides individuals the opportunities to learn about the genetics, disease characteristics, and treatment options in order to reduce morbidity and mortality in themselves and their family members. Further research is necessary to identify and explore the barriers to sharing genetic information with at-risk family members.

Motivation to Pursue Genetic Testing in Individuals with a Personal or Family History of Cardiac Events or Sudden Cardiac Death

Genetic testing is becoming increasingly available for cardiac channelopathies, such as long QT syndrome and Brugada syndrome, which can lead to sudden cardiac death. Test results can be used to shape an individual’s medical management and to identify at-risk family members. In our qualitative study, all participants had a personal or family history of a diagnosed cardiac arrhythmia syndrome or sudden cardiac death. Open-ended interviews were conducted individually and in focus groups. Interviews were audio recorded, transcribed verbatim, and analyzed using a qualitative grounded-theory approach. Of 50 participants, 37 described their motivations for pursuing genetic testing for long QT syndrome or another cardiac channelopathy. Participants’ motivations included: to find an explanation for a family member’s sudden death, to relieve uncertainty regarding a diagnosis, to guide future medical management, to allay concern about children or other family members, and to comply with recommendations of physicians or family members. Perceived reasons not to pursue genetic testing included denial, fear, and lack of information. The genetic counseling and informed consent process can be enhanced by understanding and addressing an individual’s internal and external motivations either for or against pursuing genetic testing.

Differentiation of Arrhythmias in the Dog by Measurement of Activation Sequence Using an Atrial and Two Ventricular Electrodes

Timing of atrioventricular activation and ventricular dispersion identifies and discriminates between beats of different origin. In eight dogs, three bipolar epicardial electrodes recorded left atrial and left and right ventricular depolarizations simultaneously during arrhythmias induced by programmed electrical stimulation and coronary artery occlusion and release. The interval between the left atrial and left ventricular intrinsic deflections (V1‐V2) and between the left ventricular and right ventricular intrinsic deflections (V1‐V2) of each heat was measured. Recordings were of normal sinus rhythm (NSR) (mean of five beats in 8/8 dogs), atrial flutter (AFL) (five beats of one episode), atrial fibrillation (AF) (144 beats in 29 episodes in 7/8), monomorphic ventricular tachycardia (MVT) (24 beats with six morphologies in 2/8), polymorphic ventricular tachycardia (PVT) (63 beats in 15 episodes in 5/8) and premature ventricular contractions (PVC) (29 beats with 29 morphologies in 5/8). Supraventricular rhythms can be differentiated from ventricular rhythms by V1‐V2 timing. The mean difference in V1‐V2 during AFL and AF vs NSR was 1 ms (range of 0–3 ms). The change from sinus during MVT ranged from 38 to 43 ms (m 31 ms) and during PVC 10 to 75 ms (m 38 ms). Thirty‐five of 35 of these ectopic ventricular morphologies exhibited 10 ms or more timing difference compared to corresponding beats of NSR. PVT was consistently distinguished from supraventricular rhythms and MVT by the variability of V1‐V2,A‐V1 intervals can be used to distinguish supraventricular arrhythmias from sinus rhythm; a 32 ms difference existed for AFL. AF could be detected by the variability in AV1. One atrial and two ventricular leads can provide a means of differentiating normal sinus rhythm from supraventricular and ventricular arrhythmias that may be applicable to implantable antitachycardia devices.

Differentiation of sinus rhythms from supraventricular tachydysrhythmias by activation sequence and timing

WALSH, C.A., ET AL.: Differentiation of Sinus Rhythms from Supraventricular Tachydysrhythmias by Activation Sequence and Timing. Implantable device detection of tachydysrhythmias remains unreliable and inexact. False responses may occur because of misinterpretation of sinus tachycardia (ST) as a supraventricular tachydysrhythmia (SVTD). Timing of atrioventricular (AV) activation and ventricular dispersion identified and discriminated between ST and SVTDs in 11 dogs. Three bipolar epicardial electrodes recorded left atrial and left and right ventricular depolarizations simultaneously during normal sinus rhythm (NSRJ (mean of 5 beats in 11/11 dogs), ST produced by phlebotomy (50 beats in 10 episodes in 6/11) or isoproterenol infusion (105 beats in 21 episodes in 10/11), sinus bradycardia (SB) produced by vagal stimulation (140 beats in 29 episodes in 10/11), and during atrial flutter (AFL) (15 beats in 3 episodes in 3/11) and atrial fibrillation (AF) (152 beats in 31 episodes in 9/11) induced by programmed electrical stimulation. During lidocaine infusion, NSR (55 beats in 11 episodes in 10/11 dogs), SB (84 beats in 17 episodes in 7/11), AFL (10 beats in 2 episodes in 1/11], and AF (103 beats in 21 episodes in 7/11) were recorded. During isoproterenol infusion, SB (45 beats in 9 episodes in 5/11), AFL (15 beats in 3 episodes in 2/11), and AF (64 beats in 13 episodes in 5/11) were recorded in addition to ST. The interval between the left atrial and left ventricular intrinsic deflections (A‐V1) and between the left and right ventricular intrinsic deflections (V1‐V2) of each beat was measured. The mean value (msec) of A‐V1 and V1‐V2 in each episode was compared to NSR in the same dog. A difference of ≥ 16 ms was used for differentiation. In all cases except SB with first‐degree AV block, V1‐V2 in each episode was insignificant (0‐14msec), categorizing the rhythms as supraventricular. During NSR, ST and SB without AV block, Δ A‐V1 was small (0–15 msec). In contrast Δ A‐V1 was ≥ 16 ms in 6/8 episodes of AFL. The remaining two episodes could be differentiated by the greater number of atrial versus ventricular beats. AF could be detected by the variability of A‐V1. An algorithm using the relative number of atrial vs ventricular beats and A‐V1 and V1‐V2 timing can provide automated dysrhythmia detection, without effect from lidocaine or isoproterenol infusion.

Translating Advances in Cardiogenetics Into Effective Clinical Practice

In this article we describe a qualitative research study in which we explored individuals’ subjective experiences of both genetic testing and cardiogenetic disorders. Using a grounded theory approach, we coded and analyzed interview and focus group transcripts from 50 participants. We found that just under half of the participants who received their diagnosis during the study reported difficulty understanding information about both the purpose of genetic testing and their cardiac disease. A high level of anxiety about genetic testing and cardiac symptoms exacerbated individuals’ cognitive confusion. Participants reported both positive and negative interactions with the medical community, depending on health care professionals’ knowledge of cardiogenetic disorders. Overall, participants expressed a range of attitudes—positive, negative, and ambivalent—toward genetic testing. We conclude with a discussion of the barriers to achieving effective clinical care for genetic conditions and offer suggestions for improving collaborative decision making between physicians and patients.

Transfusion-associated Babesiosis in a 7-month-old Infant after Bidirectional Glenn Procedure

We describe a case of transfusion-associated babesiosis following bidirectional Glenn procedure. This unique case highlights the importance of including babesiosis and other typically vector-borne infections in the differential diagnosis for patients with recent blood transfusions and fever without obvious source.

Perceptions of an Implantable Cardioverter-Defibrillator: A Qualitative Study of Families with a History of Sudden, Life-Threatening Cardiac Events, and Recommendations to Improve Care

OBJECTIVE To identify major concerns associated with implantable cardioverter-defibrillators (ICDs) and to provide recommendations to adult and pediatric physicians involved in the care of patients with ICDs. BACKGROUND Cardiac ion channelopathies are a well-recognized cause of sudden cardiac death in infants, children, adolescents, and young adults. ICDs are effective in preventing sudden death from fatal arrhythmias in patients with known cardiac channelopathies. There is a paucity of research on the effect of ICDs on quality of life in patients with cardiac channelopathy diagnoses, especially young patients. METHODS A qualitative study interviewing patients and families affected by inherited arrhythmias was conducted. Fifty participants with personal or family histories of cardiac events or sudden death were interviewed individually or in focus groups by clinical psychologists. All interviews were transcribed verbatim and then analyzed and coded based on current qualitative research theory to identify themes related to the research question. Twenty-four participants discussed ICDs in their interviews. RESULTS Participants reported concerns about ICDs, and these concerns were categorized into six themes: (1) comprehension and physician-patient communication; (2) anxiety; (3) restrictions and fallacies; (4) complications; (5) utility; and (6) alternative therapy. Participants noted communication breakdowns between providers and their colleagues, and between providers and their patients. Participants and their families experienced many different forms of anxiety, including worry about the aesthetics of the ICDs and fears of being shocked. Multiple restrictions, fallacies, and complications were also cited. CONCLUSION Interview themes were used to formulate recommendations for counseling and educating patients with ICDs.