Feeling a Little Blue After Ablation: Iatrogenic Atrial Septal Defect With Right-to-Left Shunt Following Atrial Fibrillation Ablation.

Atrial fibrillation is the most common cardiac arrhythmia. Cardiac ablation is indicated for patients refractory to medical management. During the ablation process, a transseptal puncture is utilized to access and isolate the pulmonary veins, which results in a temporary iatrogenic atrial septal defect (iASD). Generation of an iASD is considered unavoidable and is a generally accepted risk due to high rates of spontaneous closure. Studies have shown that persisting iASD may occur in 5%-20% of patients for up to nine to 12 months after undergoing radiofrequency ablation and that spontaneous rates of closure are high in patients with normal intracardiac pressures. Patients with preexisting elevated right intracardiac pressures from pulmonary hypertension or other right-sided cardiac pathology are at an increased risk of complications from iASD. These increased pressures can lead to clinically significant hypoxemia from right-to-left shunting following a transseptal puncture. Intervention with closure is considered in high-risk settings such as right atrial or ventricular enlargement, right-to-left shunting with hypoxemia, and intraseptal defect greater than 8 mm. This case vignette describes a 67-year-old female who developed clinically significant right-to-left shunting intraoperatively from iASD with ongoing hypoxemia for several months but with spontaneous closure. We highlight this case as it demonstrates spontaneous closure in a high-risk iASD. We also provide a review of the literature on iASD after cardiac ablations.

Pulsed Field Ablation and Neurocardiology: Inert to Efferents or Delayed Destruction?

Background: The therapeutic use of irreversible electroporation in clinical cardiac laboratories, termed pulsed field ablation (PFA), is gaining pre-regulatory approval momentum among rhythm specialists for the mitigation of arrhythmogenic substrate without increased procedural risk. Though electroporation has been utilized in other branches of science and medicine for decades, apprehension regarding all the possible off-target complications of PFA have yet to be thoroughly identified and investigated. Methods: This brief review will summarize the preclinical and adult clinical data published to date on PFA's effects on the autonomic system that interplays closely with the cardiovascular system, termed the neurocardiovascular system. These data are contrasted with the findings of efferent destruction secondary to thermal cardiac ablation modalities, namely radiofrequency energy and liquid nitrogen-based cryoablation. Results: In vitro neurocardiology findings, in vivo neurocardiology findings, and clinical neurocardiology findings to date nearly unanimously support the preservation of a critical mass of perineural structures and extracellular matrices to allow for long-term nervous regeneration in both cardiac and non-cardiac settings. Conclusions: Limited histopathologic data exist for neurocardiovascular outcomes post-PFA. Neuron damage is not only theoretically possible, but has been observed with irreversible electroporation, however regeneration is almost always concomitantly described.

Analysis of the swine tracheobronchial lymph node transcriptomic response to infection with a Chinese highly pathogenic strain of porcine reproductive and respiratory syndrome virus.

BACKGROUND: Porcine reproductive and respiratory syndrome virus (PRRSV) is a major pathogen of swine worldwide. Emergence in 2006 of a novel highly pathogenic PRRSV (HP-PRRSV) isolate in China necessitated a comparative investigation into the host transcriptome response in tracheobronchial lymph nodes (TBLN) 13 days post-infection with HP-PRRSV rJXwn06, PRRSV strain VR-2332 or sham inocula. RNA from each was prepared for next-generation sequencing. Amplified library constructs were directly sequenced and a list of sequence transcripts and counts was generated using an RNAseq analysis pipeline to determine differential gene expression. Transcripts were annotated and relative abundance was calculated based upon the number of times a given transcript was represented in the library. RESULTS: Major changes in transcript abundance occurred in response to infection with either PRRSV strain, each with over 630 differentially expressed transcripts. The largest increase in transcript level for either virus versus sham-inoculated controls were three serum amyloid A2 acute-phase isoforms. However, the degree of up or down-regulation of transcripts following infection with HP-PRRSV rJXwn06 was greater than transcript changes observed with US PRRSV VR-2332. Also, of 632 significantly altered transcripts within the HP-PRRSV rJXwn06 library 55 were up-regulated and 69 were down-regulated more than 3-fold, whilst in the US PRRSV VR-2332 library only 4 transcripts were up-regulated and 116 were down-regulated more than 3-fold. CONCLUSIONS: The magnitude of differentially expressed gene profiles detected in HP-PRRSV rJXwn06 infected pigs as compared to VR-2332 infected pigs was consistent with the increased pathogenicity of the HP-PRRSV in vivo.