Left Septal Atrial Tachycardias: Electrocardiographic and Electrophysiologic Characterization of a Paraseptal Focus

Left Septal Atrial Tachycardias. Objective: The objective was to characterize the electrocardiographic and electrophysiological features of focal atrial tachycardia (FAT) originating from the left septum (LS). Background: FAT is recognized to occur at predefined anatomic locations rather than randomly throughout the atria. We describe the ECG and EP features of ATs originating from the LS as an important site for apparent perinodal tachycardias. Methods: Nine patients presenting with LS FAT from a consecutive series of 384 underwent EP/RFA for symptomatic FAT. Results: The mean age was 56 ± 12 years; 7 female with symptoms for 36 ± 28 months. P wave morphology (PWM) was negative/positive in lead V1 and across the precordial leads and negative or negative/positive in inferior leads in all patients. Tachycardia was incessant in 6 out of 9 patients with a mean tachycardia cycle length 421 ± 56 milliseconds. His A was ahead of P wave in all patients (mean ?15 ± 5 milliseconds) and earlier than CS proximal (mean 4 ± 9 milliseconds). Successful acute focal ablation achieved at a mean of 31 ± 12 milliseconds ahead of P wave with no recurrences at a mean follow‐up of 30 ± 28 months. Conclusion: Although the left septum is an uncommon site for focal AT an awareness of this location for harboring foci is particularly important when mapping apparently right‐sided septal tachycardias. (J Cardiovasc Electrophysiol, Vol. 24, pp. 413‐418, April 2013)     

ATP1A3 mutations in infants: a new rapid‐onset dystonia–Parkinsonism phenotype characterized by motor delay and ataxia

We report new clinical features of delayed motor development, hypotonia, and ataxia in two young children with mutations (R756H and D923N) in the ATP1A3 gene. In adults, mutations in ATP1A3 cause rapid‐onset dystonia–Parkinsonism (RDP, DYT12) with abrupt onset of fixed dystonia. The parents and children were examined and videotaped, and samples were collected for mutation analysis. Case 1 presented with fluctuating spells of hypotonia, dysphagia, mutism, dystonia, and ataxia at 9 months. After three episodes of hypotonia, she developed ataxia, inability to speak or swallow, and eventual seizures. Case 2 presented with hypotonia at 14 months and pre‐existing motor delay. At age 4 years, he had episodic slurred speech, followed by ataxia, drooling, and dysarthria. He remains mute. Both children had ATP1A3 gene mutations. To our knowledge, these are the earliest presentations of RDP, both with fluctuating features. Both children were initially misdiagnosed. RDP should be considered in children with discoordinated gait, and speech and swallowing difficulties.     

Sudden and Fatal Malfunction of a Durata Defibrillator Lead due to External Insulation Failure

Defibrillator lead malfunction can be a disastrous complication, leading to loss of protection from sudden cardiac death in a high‐risk patient population. Recognition of lead‐specific risk for failure can assist in development of focused screening or surveillance, as in the case of the Riata lead (St. Jude Medical, St. Paul, MN, USA) or the Sprint Fidelis lead (Medtronic Inc., Minneapolis, MN, USA). A case of defibrillation failure secondary to a Durata lead insulation failure is presented. A brief review of the literature and current St. Jude Medical implantable cardiac defibrillator lead design is presented. Identification of arcing is identified as a potential sign of catastrophic insulation failure.     

Rising Charges and Costs for Pediatric Catheter Ablation

Pediatric Ablation Charges and Costs Are Rising. Introduction: Catheter ablation has been shown to be effective for pediatric tachyarrhythmias, but the associated charges and costs have not been described in the recent era. Understanding such contemporary trends may identify ways to keep an effective therapy affordable while optimizing clinical outcomes. Methods: We used the 1997–2009 Kids’ Inpatient Databases to examine trends in charges and costs for pediatric catheter ablation and identify determinants of temporal changes. Results: There were 7,130 discharges for catheter ablation in the sample. Mean age at ablation was 12.1 ± 0.2 years. Patients with congenital heart disease (CHD) made up 10% of the sample. Complications occurred in 8% of discharges. Mean total charges rose 219% above inflation (from $23,798 ± 1,072 in 1997 to $75,831 ± 2,065 in 2009). From 2003 to 2009, costs rose 25% (from $20,459 ± 780 in 2003 to $25,628 ± 992 in 2009). Charges for ablation increased markedly relative to surgical procedures, but with a similar slope to other catheter‐based interventions. Multivariable analysis revealed that year (P < 0.0001), payer (P = 0.0002), CHD (P < 0.0001), valvular heart disease (P = 0.0004), cardiomyopathy (P = 0.0009), hospital region (P < 0.0001), length of stay (P < 0.0001), and complications (P < 0.0001) predicted increased charges. The same factors also predicted increased costs. Charges and costs varied considerably by region, particularly for high‐volume centers (P < 0.0001). Conclusions: Charges and costs for pediatric catheter ablation increased relative to other procedures and significantly outstripped inflation. Further study of complications, length of stay, and regional differences may help control rising costs while maintaining quality of care. (J Cardiovasc Electrophysiol, Vol. 24, pp. 162‐169, February 2013)     

Late Gadolinium Enhancement of the Esophagus is Common on Cardiac MR Several Months after Pulmonary Vein Isolation: Preliminary Observations

Background: Pulmonary vein isolation (PVI) as a treatment for atrial fibrillation (AF) is commonly performed. This procedure can damage the esophagus. Late gadolinium enhancement (LGE) cardiovascular magnetic resonance imaging (CMR) offers noninvasive assessment of scar. We sought to examine the prevalence of esophageal hyperenhancement on LGE‐CMR prior to and following PVI. Methods: Seventy‐four patients underwent LGE‐CMR prior to and 1.7 ± 1.9 months post PVI for AF. Transmural esophageal hyperenhancement was visually assessed. The pre‐ and post PVI esophageal position was measured, relative to the vertebral body. Results: Prior to PVI, 3% (2/74) of patients had esophageal LGE on CMR. At post‐PVI follow‐up, 30% (23/74) of the studies demonstrated new esophageal hyperenhancement adjacent to an ablation site. Most (74%, 17/27) positive esophageal LGE studies were performed >30 days after PVI, while no (0/9) studies performed >2 months post PVI were positive for esophageal hyperenhancement. The presence of post‐procedural esophageal hyperenhancement was not associated with longer ablation time (P = 0.42), use of an irrigated catheter (74% with LGE vs 47% without, P = 0.16), right‐sided esophageal location (56% with LGE vs 39% without, P = 0.17), size of left atrium cavity (58 ± 8 mm with LGE vs 61 ± 10 mm without, P = 0.15), or the timing of the LGE‐CMR study after PVI (36 ± 10 days with LGE vs 60 ± 66 days without, P = 0.09). Conclusion: Though rare before PVI, new esophageal LGE is seen in almost one‐third of patients after PVI. The clinical implications to remain to be explored, but clinicians should be aware of this frequent imaging finding. (PACE 2010; 33:661–666)     

Properties of a Resiniferatoxin-stimulated,Calcium Inhibited but Phosphatidylserine-dependent Kinase,which is Distinct from Protein Kinase C Isotypes α, β1γ, δ, ε and η

We have separated a resiniferatoxin-stimulated histone-kinase activity from human neutrophils, elicited mouse macrophages and murine alveolar macrophages by hydroxyapatite chromatography. The assay conditions for resiniferatoxin kinase were optimized as part of this study and in the presence of phosphatidylserine but absence of Ca²⁺ the K_a for histone IIIs phosphorylation by resiniferatoxin was calculated as 16 nm . Using a phosphate gradient of 20–500 mm , peaks of protein kinase C activity could be washed from the hydroxyapatite column in 300 nm phosphate and resiniferatoxin kinase recovered in 500 mm phosphate. At the optimum concentration of 160 nm , the ability of resiniferatoxin to induce enzyme activity was compared with a range of phorbol esters all at the same concentration. These related compounds failed to activate resiniferatoxin kinase although they have previously been shown to activate protein kinase C isotypes. Similarly sn-1,2,-dioleoylglycerol and the potent irritant capsaicin at 30 μm failed to activate the kinase. A Scatchard analysis of [³H] phorbol dibutyrate binding produced a linear plot (K_d 41·6 nm ; B_max 11·6 fmol unit^?1) and binding was inhibited by resiniferatoxin and 12-O-tetradecanoylphorbol-13-acetate (TPA), with resiniferatoxin 700 times more potent than TPA in this respect. A radiolabeled resiniferatoxin binding assay was also used to demonstrate specific binding of [³H]resiniferatoxin which could be inhibited by unlabelled compound. Resiniferatoxin kinase activity was shown to be distinct from the protein kinase C isotypes α, β₁, γ δ and ε by means of immunological analysis and from the η isotype, because that isotype was not stimulated by resiniferatoxin but was stimulated by TPA when a pseudosubstrate was used. In addition the resiniferatoxin-stimulated activity was inhibited in-vitro by the addition of Ca²⁺ (K_i 0·1-0·5 nm free Ca²⁺). Further purification of resiniferatoxin kinase by Superose chromatography indicated a major activity fraction of about 70–90 kDa. Thus resiniferatoxin kinase, isolated from human and mouse inflammatory cells is distinct from the known isotypes of protein kinase C and is a major resiniferatoxin receptor.