Device-detected nonsustained ventricular tachycardia in adult congenital heart disease without tetralogy of fallot.

OBJECTIVES: To evaluate any association between non-sustained ventricular tachycardia (NSVT) detected by intra-cardiac device and clinical outcomes in repaired adult congenital heart disease (ACHD) without tetralogy of Fallot (TOF). BACKGROUND: NSVT portends a higher risk of serious ventricular tachyarrhythmia in TOF. However its clinical significance when incidentally detected by implantable cardiac device is not well elucidated in non-TOF ACHD cohort. METHODS: We performed a single center, retrospective, longitudinal follow-up study in repaired ACHD (≥18 years) patients without TOF who hosted a pacemaker or automatic implantable cardiac defibrillator (AICD). The cohort was divided based on presence/absence of device detected NSVT. The primary end-point was a composite of sustained ventricular tachycardia (VT), ventricular fibrillation (VF), or sudden cardiac death (SCD). RESULTS: One hundred fifty eight patients (male 56.3%, median [IQR] age of 35 [28-43] years at last follow-up] with longitudinal post-implant follow-up duration of 8 (5-12) years were included. NSVT was detected in 52 (33%) patients. The primary composite end-point was more frequent in NSVT group [11.5% vs. 2.8%; p = .04]. Patients with NSVT were (i) older at the time of initial implant (age 25 vs. 18 years, p = .011) and more frequently demonstrated (ii) systemic ventricular dysfunction (44% vs. 26%; p = .015), as well as (iii) history of ventriculotomy (38% vs. 21%; p = .017). CONCLUSIONS: In our repaired ACHD cohort, we noted a significant association between device-detected-NSVT and the primary composite end-point of sustained VT/VF or SCD. Systemic ventricular dysfunction and history of ventriculotomy were more frequent in the NSVT group and likely constituted the clinical milieu.

Rare RYR2 p.Thr85Ile variant is associated with catecholaminergic polymorphic ventricular tachycardia.

Mutations in the cardiac ryanodine receptor 2 gene (RYR2) are noted in approximately 55% of the patients with catecholaminergic polymorphic ventricular tachycardia (CPVT). However, a high background rate of rare amino acid-altering variants in RYR2 [≈3% (whites) to 6% (nonwhites)] in combination with delayed onset and variable expressivity of the CPVT phenotype make attributing causality to rare RYR2 variants difficult. The proposed set of guidelines for characterization of variants include, among many different criteria, functional studies to classify variants as pathogenic versus non- pathogenic. However, in vitro data, especially for complex channelopathies like CPVT, does not always correlate well with the human phenotype; therefore, characterizing the phenotypic features of rare RYR2 variants in humans is of importance. We report a 13-year-old carrier of a rare maternally inherited variant in exon 3 of RYR2 (p.Thr85Ile, c.254C>T [rs772005577]) who was successfully resuscitated from exercise-associated sudden cardiac arrest and was subsequently found to have exercise-induced complex ventricular ectopy. His brother, who has been asymptomatic, was also found to carry the same variant and demonstrated complex ventricular ectopy on exercise stress testing. These findings suggest that this rare variant, which has previously not been reported in patients with RYR2 related conditions, is associated with pathogenicity.

Rapid progression of mitral valve disease in a child with Noonan syndrome.

Noonan syndrome is the second most common genetic syndrome associated with congenital heart disease after Trisomy 21. The two most common cardiac lesions associated with Noonan syndrome are pulmonary stenosis and hypertrophic cardiomyopathy. Although the incidence of mitral valve disease in Noonan syndrome ranges between 2 and 6%, rapid progression of mitral valve dysplasia causing severe mitral valve regurgitation and left atrial dilatation is seldom seen. Most cases of mitral valve disease have been diagnosed either on routine echocardiographic surveillance or when presented with heart failure symptoms. We describe an 18-month-old boy with Noonan syndrome presenting in atrial flutter due to a massively enlarged left atrium caused by severe mitral valve regurgitation which developed and progressed in less than 17 months.

Intermittent atrio-ventricular block and ectopy in an infant following complex heart surgery: Occam's razor versus Hickam's dictum.

Concealed functional extra-systole manifesting as pseudo Mobitz Type II Second Degree A-V Block.

Near-infrared Spectroscopy to Assess Cerebral Perfusion during Head-up Tilt-table Test in Patients with Syncope.

OBJECTIVE: Neurocardiogenic syncope (NCS) is the most common cause of syncope in children and adolescents. Neurocardiogenic syncope occurs secondary to cerebral hypotension because of bradycardia, hypotension, or both. Head-up tilt-table test (HUTT) is the primary diagnostic test. Near-infrared spectroscopy (NIRS) is a noninvasive technology that directly monitors trends in regional tissue oxygen saturations over a specific body region. Placing an NIRS probe over the temporal region allows an indirect measurement of cerebral perfusion. Our hypothesis is that regional tissue oxygen saturation will decrease during an NCS episode and will remain stable in patients without syncope. PATIENTS AND DESIGN: The investigators conducted a retrospective review of all HUTT utilizing cephalic NIRS performed at our institution from August 2012 to January 2013. Tests were classified as positive, negative, or psychogenic reactions. Paired t-test was used to determine statistical significance of NIRS changes and one-way analysis of variance was used to analyze baseline characteristics among the three groups. RESULTS: Twelve patients were included in the study (female = 10). The average age was 14.4 years (range: 12-17). Five tests were positive for NCS, four were negative, and three demonstrated psychogenic reactions. Patients with a positive test had a sudden, significant decrease in regional tissue oxygen saturations (P = .009) by an average of 11.3 ± 5.2% compared with baseline. The decrease in regional tissue oxygen saturation preceded symptoms, hypotension, and bradycardia in all patients. Regional tissue oxygen saturation levels remained stable in patients with a negative test or psychogenic syncope. CONCLUSIONS: NIRS monitoring during HUTT produces a reliable, positive result that precedes clinical signs and symptoms. Further, it helps distinguish NCS from psychogenic syncope.

Apoptosis in the developing mouse heart.

Apoptosis occurs at high frequency in the myocardium of the developing avian cardiac outflow tract (OFT). Up- or down-regulating apoptosis results in defects resembling human conotruncal heart anomalies. This finding suggested that regulated levels of apoptosis are critical for normal morphogenesis of the four-chambered heart. Recent evidence supports an important role for hypoxia of the OFT myocardium in regulating cell death and vasculogenesis. The purpose of this study was to determine whether apoptosis in the outflow tract myocardium occurs in the mouse heart during developmental stages comparable to the avian heart and to determine whether differential hypoxia is also present at this site in the murine heart. Apoptosis was detected using a fluorescent vital dye, Lysotracker Red (LTR), in the OFT myocardium of the mouse starting at embryonic day (E) 12.5, peaking at E13.5-14.5, and declining thereafter to low or background levels by E18.5. In addition, high levels of apoptosis were detected in other cardiac regions, including the apices of the ventricles and along the interventricular sulcus. Apoptosis in the myocardium was detected by double-labeling with LTR and cardiomyocyte markers. Terminal deoxynucleotidyl transferase-mediated deoxyuridinetriphosphate nick end-labeling (TUNEL) and immunostaining for cleaved Caspase-3 were used to confirm the LTR results. At the peak of OFT apoptosis in the mouse, the OFT myocardium was relatively hypoxic, as indicated by specific and intense EF5 staining and HIF1alpha nuclear localization, and was surrounded by the developing vasculature as in the chicken embryo. These findings suggest that cardiomyocyte apoptosis is an evolutionarily conserved mechanism for normal morphogenesis of the outflow tract myocardium in avian and mammalian species.