Faculty Bibliography

Background: Long QT syndrome (LQTS) may present in the fetus or neonate with signature rhythms of torsades de pointes (TdP) or AV block (AVB).
Objective(s): To describe management and outcomes of a signature perinatal LQTS presentation.
Method(s): This is an ongoing retrospective study currently involving 11 centers. Patients were included for in utero or neonatal (<30 days) TdP/AVB. In utero TdP was diagnosed by fMCG or echocardiographic suspicion of TdP followed by postnatal LQTS confirmation. Cardiac events were appropriate ICD discharge, aborted cardiac arrest, or death/transplant.
Result(s): Forty eligible patients were included (14 male; 20 diagnosed in utero, 1 fetal demise). All live births underwent genotyping (15 SCN5A, 8 KCNH2, 5 KCNQ1, 5 CACNA1C, 1 CALM3, 1 KCNE2, 4 negative). Median GA at delivery was 37 weeks (IQR 35, 39) and first postnatal QTc was 625 ms (561, 688). Pre-discharge management was antiarrhythmic drugs in 36, sympathectomy in 7 (6 L, 0 R, 1 bilateral), and cardiac device implantation in 22 (PM 14, ICD 8). Considering all patients, median age at first post-discharge cardiac event was 38 months with further management consisting of sympathectomy (8 L, 1 R) or device implantation (8 PM, 9 ICD). Seizures occurred in 8 patients and significant developmental delay in 10. Nine patients died (6 SCD, 1 status epilepticus, 1 brain death, 1 respiratory failure), and 2 underwent heart transplantation. LQTS genotype strongly correlated with time to first post-discharge event (Figure).
Conclusion(s): Signature LQTS presentation portends high risk for neurologic and cardiac events, especially with SCN5A/CACNA1C genotypes. Such data should be useful to inform future therapeutic strategies. [Figure presented]
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BACKGROUND:Atrial standstill is an arrhythmogenic condition characterized by the absence of spontaneous electrical and mechanical atrial activity or in response to stimulation. There are few reported familial cases which have been associated with SCN5A mutations co-segregating with GJA5 or RYR2 however isolated SCN5A mutations are rare. OBJECTIVE:The purpose of this study was to determine the clinical and biophysical consequence of a novel SCN5A mutation identified in a family with progressive atrial standstill and sudden death. METHODS:The family of a sporadic case of congenital atrial standstill underwent genetic screening. Human Embryonic Kidney 293 cells were transfected with wild-type (WT) or mutant SCN5A cDNAs. Biophysical properties were studied using whole-cell using patch clamp methods. RESULTS:A novel homozygous SCN5A mutation, p.V1340L was identified in the proband and her sister. The proband had complete atrial standstill whereas the sister had partial atrial standstill. Heterozygous mutations were identified in the mother, father and brother. All three had normal sinus rhythm and were asymptomatic. The mutant Nav1.5(V1340L) reduced Nav1.5 current density as well as showed a depolarizing shift in the voltage-dependent steady-state activation (WT: -35.3±1.62 mV; V1340L: -22.4±2.59 mV; P = 0.001). CONCLUSIONS:A homozygous loss-of-function SCN5A mutation likely results in atrial standstill and sudden death due to suppression of initiation of action potential.

In patients with partial anomalous pulmonary venous return of the right superior pulmonary veins to the superior vena cava, surgical repair generally consists of either intraatrial baffle with or without caval enlargement, or superior caval transection and cavoatrial anastomosis to the right atrial appendage. We discuss here a novel technique of superior caval enlargement without need for patch material or reimplantation.

In patients with tetralogy of Fallot (TOF) repair and a borderline pulmonary valve annulus (PVA) size, surgical repair often necessitates a transannular incision and subsequent placement of a patch with or without a monocusp or, alternatively, a right ventricle-to-pulmonary artery conduit. We discuss here a technique in which the pulmonary valve annulus can be safely preserved, with infrequent postoperative issues as well as the potential for less incidence of right ventricular outflow intervention in the long term.

Few data exist regarding the efficacy and safety of the Amplatzer ductal occluder (ADO) type 1 device in the Asian region. This retrospective study, conducted between August 2001 and April 2011, attempted device placement for 231 patients (165 females and 66 males) with a median age of 7.4 years (range, 3 months to 64 years) and an average weight of 19.4 kg (range, 4.1-81.0 kg). Among the patients in this study, 66 (28.6%) had pulmonary hypertension, ten (4.3%) had trisomy 21, and eight (3.5%) had other congenital cardiac anomalies. The mean narrowest patent ductus arteriosus (PDA) diameter was 4.2 mm (range, 1.3-10 mm), and the ampulla size was 9.6 mm (range, 4-20 mm). Successful implantation was achieved for 229 patients (99.1%). Complete angiographic occlusion was achieved for 201 patients (87.8%) at the end the procedure. Follow-up data were available for 129 patients (66%). At the follow-up assessment, complete echocardiographic occlusion was seen in 128 patients (99.2%) after 1 month and in 100% of the patients after 6 months. The significant morbidities involved one device embolization and one dislodgment, for which surgical retrieval was performed. No mortalities occurred during the study period, and no late clinical adverse events occurred during the follow-up period. Occlusion of the PDA using ADO is safe, effective, and applicable for a wide range of PDA sizes including large PDAs in small symptomatic infants and in adults. Good outcomes can be attributed to experience of the operators, proper patient selection, and appropriate device size selection.