Venoarterial Extracorporeal Membrane Oxygenation and Implantable Cardioverter-Defibrillator Implantation in a Hemodynamically Unstable Infant with Ventricular Tachycardia from Multiple Cardiac Rhabdomyomas

Tuberous sclerosis complex (TSC) is a neurocutaneous disorder characterized by benign tissue hamartomas in multiple organ systems, including cardiac rhabdomyomas. Though prevalent in TSC, cardiac tumors are rare in children, occurring in about 0.03%–0.17%. Rhabdomyomas are the most common, accounting for 45%. When present, they are multiple and in the ventricular myocardium. Frequently, they regress and surveillance is all that is required until spontaneous regression. Intervention is necessary when life-threatening obstruction or hemodynamically significant refractory arrhythmias occur. This case highlights the course of a 6-month-old infant with TSC and cardiac rhabdomyomas who presented in refractory ventricular tachycardia (VT) with decompensation and cardiac arrest necessitating venoarterial extracorporeal membrane oxygenation (VA-ECMO), complex antiarrhythmic therapy, and ultimately implantable cardioverter-defibrillator (ICD) implantation

Novel Timothy Syndrome Mutation Leading to Increase in CACNA1C Window Current

Background Timothy syndrome (TS) is a rare multisystem genetic disorder characterized by a myriad of abnormalities, including QT prolongation, syndactyly, and neurologic symptoms. The predominant genetic causes are recurrent de novo missense mutations in exon 8/8A of the CACNA1C-encoded L-type calcium channel; however, some cases remain genetically elusive. Objective The purpose of this study was to identify the genetic cause of TS in a patient who did not harbor a CACNA1C mutation in exon 8/A, and was negative for all other plausible genetic substrates. Methods Diagnostic exome sequencing was used to identify the genetic substrate responsible for our case of TS. The identified mutation was characterized using whole-cell patch-clamp technique, and the results of these analyses were modeled using a modified Luo–Rudy dynamic model to determine the effects on the cardiac action potential. Results Whole exome sequencing revealed a novel CACNA1C mutation, p.Ile1166Thr, in a young male with diagnosed TS. Functional electrophysiologic analysis identified a novel mechanism of TS-mediated disease, with an overall loss of current density and a gain-of-function shift in activation, leading to an increased window current. Modeling studies of this variant predicted prolongation of the action potential as well as the development of spontaneous early afterdepolarizations. Conclusion Through expanded whole exome sequencing, we identified a novel genetic substrate for TS, p.Ile1166Thr-CACNA1C. Electrophysiologic experiments combined with modeling studies have identified a novel TS mechanism through increased window current. Therefore, expanded genetic testing in cases of TS to the entire CACNA1C coding region, if initial targeted testing is negative, may be warranted

Cardiac electrical system involvement in Alström syndrome: uncommon causes of dilated cardiomyopathies

Alström syndrome is a rare autosomal recessive disorder with dilated cardiomyopathy in 60% of patients. Despite the frequency of cardiac involvement in Alström syndrome, conduction system abnormalities or arrhythmias have not been characterized previously. We report two siblings with Alström syndrome with conduction system involvement with left bundle branch block on electrocardiogram (ECG). One patient had first degree atrioventricular block in addition to bundle branch block and underwent pacemaker implantation. This same patient developed intra-atrial reentry tachycardia requiring anti-arrhythmic medication and eventual trans-catheter ablation. The second patient developed atrial and ventricular arrhythmias and underwent placement of a bi-ventricular defibrillator. These findings suggest that cardiac conduction system involvement and clinical arrhythmia may be significant yet under-recognized complications in patients with Alström syndrome. Patients should be routinely screened with ECG and Holter monitoring in addition to echocardiographic assessment and a cardiologist experienced with cardiomyopathy should be an integral part of the care team

Cosmetic outcomes and quality of life in children with cardiac implantable electronic devices

BackgroundAxillary implant location is an alternative implant location in patients for cardiac implantable electronic devices (CIEDs) for the purposes of improved cosmetic outcome. The impact from the patient’s perspective is unknown. The purpose of this study was to compare scar perception scores and quality of life (QOL) in pediatric patients with axillary CIED implant location versus the standard infraclavicular approach.MethodsThis is a multicenter prospective study conducted at eight pediatric centers and it includes patients aged from 8 to 18 years with a CIED. Patients with prior sternotomy were excluded. Scar perception and QOL outcomes were compared between the infraclavicular and axillary implant locations.ResultsA total of 141 patients (83 implantable cardioverter defibrillator [ICD]/58 pacemakers) were included, 55 with an axillary device and 86 with an infraclavicular device. Patients with an ICD in the axillary position had better perception of scar appearance and consciousness. Patients in the axillary group reported, on average, a total Pediatric QOL Inventory score that was 6 (1, 11) units higher than the infraclavicular group, after adjusting for sex and race (P = 0.02).ConclusionsQOL is significantly improved in axillary in comparison to the infraclavicular CIED position, regardless of device type. Scar perception is improved in patients with ICD in the axillary position.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/147032/1/pace13522.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/147032/2/pace13522_am.pd

Presence of mechanical dyssynchrony in duchenne muscular dystrophy

<p>Abstract</p> <p>Background</p> <p>Cardiac dysfunction in boys with Duchenne muscular dystrophy (DMD) is a leading cause of death. Cardiac resynchronization therapy (CRT) has been shown to dramatically decrease mortality in eligible adult population with congestive heart failure. We hypothesized that mechanical dyssynchrony is present in DMD patients and that cardiovascular magnetic resonance (CMR) may predict CRT efficacy.</p> <p>Methods</p> <p>DMD patients (n = 236) were stratified into 4 groups based on age, diagnosis of DMD, left ventricular (LV) ejection fraction (EF), and presence of myocardial fibrosis defined as positive late gadolinum enhancement (LGE) compared to normal controls (n = 77). Dyssynchrony indices were calculated based on timing of CMR derived circumferential strain (e_cc). The calculated indices included cross-correlation delay (XCD), uniformity of strain (US), regional vector of variance (RVV), time to maximum strain (TTMS) and standard deviation (SD) of TTMS. Abnormal XCD value was defined as > normal + 2SD. US, RVV, TTMS and SD were calculated for patients with abnormal XCD.</p> <p>Results</p> <p>There was overall low prevalence of circumferential dyssynchrony in the entire DMD population; it increased to 17.1% for patients with abnormal EF and to 31.2% in the most advanced stage (abnormal EF with fibrosis). All but one DMD patient with mechanical dyssynchrony exhibited normal QRS duration suggesting absence of electrical dyssynchrony. The calculated US and RVV values (0.91 ± 0.09, 1.34 ± 0.48) indicate disperse rather than clustered dyssynchrony.</p> <p>Conclusion</p> <p>Mechanical dyssynchrony is frequent in boys with end stage DMD-associated cardiac dysfunction. It is associated with normal QRS complex as well as extensive lateral fibrosis. Based on these findings, it is unlikely that this patient population will benefit from CRT.</p

Arrhythmia as a cardiac manifestation in MELAS syndrome

A 44-year-old female with a diagnosis of mitochondrial myopathy, encephalopathy and stroke-like episodes (MELAS) syndrome had progressive left ventricular hypertrophy (LVH) on echocardiogram. A Holter monitor demonstrated episodes of non-sustained atrial tachycardia, a finding not been previously described in this population. This unique case of MELAS syndrome demonstrates the known associated cardiac manifestation of LVH and the new finding of atrial tachycardia which may represent the potential for subclinical arrhythmia in this population