Significant procedure length reduction when utilizing active esophageal cooling – a six-year single center study

Background

A number of factors can influence procedure duration of left atrial ablation for the treatment of atrial fibrillation (AF). In addition to ablation techniques, the use of auxiliary tools such as intraoperative fluoroscopy and luminal esophageal temperature (LET) monitoring may impact procedure duration. However, unlike recent trends toward zero-fluoroscopy procedures, there has not been a widespread transition to alternative means of esophageal protection. Multi sensor LET monitoring leads to frequent pauses during ablations when dangerous esophageal temperatures have been reached. Although an increased risk of esophageal injury when utilizing LET monitoring as compared to active esophageal cooling has been suggested in recent studies, the degree to which LET monitoring impacts procedure duration has not been well documented. Consequently, we aimed to compare procedure duration in a large single center before and after active esophageal cooling was implemented in place of LET monitoring.

Objective

Review procedural timing data at a single large hospital before and after the implementation of active esophageal cooling in place of LET monitoring, and compare differences in procedure duration.

Methods

Using an existing hospital registry of ablation procedures, we obtained procedure durations for left atrial ablations for AF before and after the implementation of active esophageal cooling into the hospital protocol. Data was collected with IRB approval from a single hospital from January 2015 through November 2021. Prior to September 2018, multi-sensor LET monitoring was utilized in all patients, whereas all patients afterwards were treated with active esophageal cooling.

Results

Data was analyzed from a total of 412 patients. LET monitoring was utilized with 176 patients, while active esophageal cooling was utilized with 236 patients. In the LET monitored group the median procedure length was 191 minutes with an interquartile range (IQR) of 91 minutes. In the actively cooled group, the median procedure length was 147 minutes with an IQR of 61 minutes. This represents a median difference of 44 minutes, or 23% of total procedure time (p<0.001).

Conclusion

When compared to LET monitoring, the use of active esophageal cooling is associated with a significant time savings in PVI procedures.

Funding Acknowledgement

Type of funding sources: Private company. Main funding source(s): Attune Medical

Arrhythmia recurrence reduction with an active esophageal cooling device during radiofrequency ablation

Funding Acknowledgements

Type of funding sources: None.

Background

As the burden of atrial fibrillation continues to rise with an aging population, there have been contrasting positions on the efficacy of left atrial ablation. While ablation techniques have continued to improve over the past decades, arrhythmia recurrence rates must be further reduced given the burden of ablation on patients. Since continuity of lesion sets has been associated with greater lesion durability, it has been theorized that the use of active esophageal cooling may facilitate greater freedom from arrhythmia.

Purpose

In order to investigate the association between use of active esophageal cooling and arrhythmia recurrence, we performed a multicenter retrospective study of arrhythmia recurrence rates in patients that received active cooling and compared them to those that received luminal esophageal temperature (LET) monitoring.

Methods

In this study, follow up data were collected from patients that underwent pulmonary vein isolation (PVI) at three separate large medical centers. Data were contained in a prospective hospital registry, a prospective physician registry, or the electronic health record, depending on the center. For each patient included, we recorded whether their ablation utilized LET monitoring or active esophageal cooling, along with their rhythm status at 1-year follow up. Rhythm status at follow-up was determined by either electrocardiogram, Holter monitor, or wearable heart rate monitor. Kaplan-Meier (KM) curves were created for freedom-from-arrhythmia at one year comparing those in the LET monitoring group to those in the active cooling group.

Results

Follow up data were collected from 1035 patients. There were 560 patients that received LET monitoring during their original ablation, and 475 patients that underwent active esophageal cooling. KM estimates for freedom-from-arrhythmia at one year were 42% in the LET monitored group and 65% in the actively cooled group (P<.001).

Conclusion

In this large multicenter study, there is a significant increase in freedom-from-arrhythmia at one year follow-up among patients that received active esophageal cooling as compared to those that underwent LET monitoring.

Effect of a proactive esophageal cooling device on procedure length - a multicenter comparison of persistent and paroxysmal atrial fibrillation

Funding Acknowledgements

Type of funding sources: None.

Background

During left atrial ablation for the treatment of atrial fibrillation (AF), effective esophageal protection is essential for reducing or preventing thermal injury. Traditional methods include luminal esophageal temperature (LET) monitoring that lead to frequent pauses in the procedure when temperature alarms alert operators to dangerous temperature levels. While there have been recent studies that demonstrate an association between active esophageal cooling and a reduction in procedure duration regardless of AF type, these retrospective studies have been conducted at single or joint centers which may lead to confounding from other time-saving variables that have changed over time.

Purpose

Consequently, we sought to perform a large-scale multicenter comparison to better elucidate the association between procedure length and the use of active cooling in patients with persistent and paroxysmal atrial fibrillation.

Methods

In this study, we collected data from three large hospital centers, one hospital-maintained registry, one physician-maintained registry, and one through EHR data review and aggregated in groups separated by AF type as well as whether the patients received active cooling or LET monitoring. We then compared median procedure durations in each group.

Results

There were a total of 753 patients included in this study. Of the 360 patients with paroxysmal AF, 179 received active esophageal cooling while 181 underwent LET monitoring. In the persistent AF group with 393 patients, 157 received active esophageal cooling and 236 underwent LET monitoring. Among patients with paroxysmal AF, the median mean procedure duration was 137 minutes in the LET monitored group, and 90 minutes in the actively cooled group with an overall reduction of 47 minutes (P<.001). In patients with persistent AF, the median procedure duration was 148 minutes in the LET monitored group and 94 minutes in the actively cooled group with an overall reduction of 54 minutes (P<.001). The relative reduction as a percent of total procedure time was 34%, and 36%, for paroxysmal and persistent AF cases, respectively.

Conclusion

In this large multicenter review, there is a significant reduction in procedure length when using active esophageal cooling, regardless of AF type.

Association of a variant in the muscarinic acetylcholine receptor 2 gene (CHRM2) with nicotine addiction

Genetic factors contribute to the overall risk of developing nicotine addiction, which is the major cause of preventable deaths in western countries. However, knowledge regarding specific polymorphisms influencing smoking phenotypes remains scarce. In the present study we provide evidence that a common single nucleotide polymorphism (SNP) in the 5' untranslated region of CHRM2, the gene coding for the muscarinic acetylcholine receptor 2 is associated with nicotine addiction. CHRM2 was defined as a candidate gene for nicotine addiction based on previous evidence that linked variations in CHRM2 to alcohol and drug dependence. A total of more than 5,500 subjects representative of the German population were genotyped and assessed regarding their smoking habits. The impact of three SNPs in CHRM2 on smoking behavior/nicotine addiction was investigated using logistic regression models or a quasi-Poisson regression model, respectively. We found the T allele of SNP rs324650 to be associated with an increased risk of smoking/nicotine dependence according to three different models, the recessive models of regular or heavy smokers vs. never-smokers (odds ratio 1.17 in both analyses) and according to the Fagerström index of nicotine addiction. In the analysis stratified by gender this association was only found in females. Our data provide further evidence that variations in CHRM2 may be associated with the genetic risk of addiction in general or with certain personality traits that predispose to the development of addiction. Alternatively, variations in CHRM2 could modulate presynaptic auto-regulation in cholinergic systems and may thereby affect an individual's response to nicotine more specifically.

A genome-wide association study in chronic obstructive pulmonary disease (COPD): identification of two major susceptibility loci

There is considerable variability in the susceptibility of smokers to develop chronic obstructive pulmonary disease (COPD). The only known genetic risk factor is severe deficiency of α₁-antitrypsin, which is present in 1–2% of individuals with COPD. We conducted a genome-wide association study (GWAS) in a homogenous case-control cohort from Bergen, Norway (823 COPD cases and 810 smoking controls) and evaluated the top 100 single nucleotide polymorphisms (SNPs) in the family-based International COPD Genetics Network (ICGN; 1891 Caucasian individuals from 606 pedigrees) study. The polymorphisms that showed replication were further evaluated in 389 subjects from the US National Emphysema Treatment Trial (NETT) and 472 controls from the Normative Aging Study (NAS) and then in a fourth cohort of 949 individuals from 127 extended pedigrees from the Boston Early-Onset COPD population. Logistic regression models with adjustments of covariates were used to analyze the case-control populations. Family-based association analyses were conducted for a diagnosis of COPD and lung function in the family populations. Two SNPs at the α-nicotinic acetylcholine receptor (CHRNA 3/5) locus were identified in the genome-wide association study. They showed unambiguous replication in the ICGN family-based analysis and in the NETT case-control analysis with combined p-values of 1.48×10⁻¹⁰, (rs8034191) and 5.74×10⁻¹⁰ (rs1051730). Furthermore, these SNPs were significantly associated with lung function in both the ICGN and Boston Early-Onset COPD populations. The C allele of the rs8034191 SNP was estimated to have a population attributable risk for COPD of 12.2%. The association of hedgehog interacting protein (HHIP) locus on chromosome 4 was also consistently replicated, but did not reach genome-wide significance levels. Genome-wide significant association of the HHIP locus with lung function was identified in the Framingham Heart study (Wilk et al., companion article in this issue of PLoS Genetics; doi:10.1371/journal.pgen.1000429). The CHRNA 3/5 and the HHIP loci make a significant contribution to the risk of COPD. CHRNA3/5 is the same locus that has been implicated in the risk of lung cancer.

There is considerable variability in the susceptibility of smokers to develop chronic obstructive pulmonary disease (COPD), which is a heritable multi-factorial trait. Identifying the genetic determinants of COPD risk will have tremendous public health importance. This study describes the first genome-wide association study (GWAS) in COPD. We conducted a GWAS in a homogenous case-control cohort from Norway and evaluated the top 100 single nucleotide polymorphisms in the family-based International COPD Genetics Network. The polymorphisms that showed replication were further evaluated in subjects from the US National Emphysema Treatment Trial and controls from the Normative Aging Study and then in a fourth cohort of extended pedigrees from the Boston Early-Onset COPD population. Two polymorphisms in the α-nicotinic acetylcholine receptor 3/5 locus on chromosome 15 showed unambiguous evidence of association with COPD. This locus has previously been implicated in both smoking behavior and risk of lung cancer, suggesting the possibility of multiple functional polymorphisms in the region or a single polymorphism with wide phenotypic consequences. The hedgehog interacting protein (HHIP) locus on chromosome 4, which is associated with COPD, is also a significant risk locus for COPD.

A genome-wide investigation of SNPs and CNVs in schizophrenia

We report a genome-wide assessment of single nucleotide polymorphisms (SNPs) and copy number variants (CNVs) in schizophrenia. We investigated SNPs using 871 patients and 863 controls, following up the top hits in four independent cohorts comprising 1,460 patients and 12,995 controls, all of European origin. We found no genome-wide significant associations, nor could we provide support for any previously reported candidate gene or genome-wide associations. We went on to examine CNVs using a subset of 1,013 cases and 1,084 controls of European ancestry, and a further set of 60 cases and 64 controls of African ancestry. We found that eight cases and zero controls carried deletions greater than 2 Mb, of which two, at 8p22 and 16p13.11-p12.4, are newly reported here. A further evaluation of 1,378 controls identified no deletions greater than 2 Mb, suggesting a high prior probability of disease involvement when such deletions are observed in cases. We also provide further evidence for some smaller, previously reported, schizophrenia-associated CNVs, such as those in NRXN1 and APBA2. We could not provide strong support for the hypothesis that schizophrenia patients have a significantly greater "load" of large (>100 kb), rare CNVs, nor could we find common CNVs that associate with schizophrenia. Finally, we did not provide support for the suggestion that schizophrenia-associated CNVs may preferentially disrupt genes in neurodevelopmental pathways. Collectively, these analyses provide the first integrated study of SNPs and CNVs in schizophrenia and support the emerging view that rare deleterious variants may be more important in schizophrenia predisposition than common polymorphisms. While our analyses do not suggest that implicated CNVs impinge on particular key pathways, we do support the contribution of specific genomic regions in schizophrenia, presumably due to recurrent mutation. On balance, these data suggest that very few schizophrenia patients share identical genomic causation, potentially complicating efforts to personalize treatment regimens.

Interferon-alpha-2b induced signal transduction and gene regulation in patient immune cells is not enhanced by a dose increase from 5 MU/m2 to 10 MU/m2

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Background: High dose interferon-alpha-2b (IFN-a) is employed as an adjuvant in melanoma patients who have had surgery for high-risk lesions. It mediates its anti-tumor effects via activation of the transcription factor STAT1 (signal transducer and activator of transcription) within host immune cells. We hypothesized that intermediate doses of IFN-a would be just as effective as higher doses in stimulating the activation of STAT1 and gene transcription in immune cells. Methods: Samples for analysis were obtained from patients with metastatic melanoma who were enrolled in a clinical trial of bevacizumab in combination with escalating doses of IFN-a (5 MU/m^2 and then 10 MU/m^2). Peripheral blood mononuclear cells (PBMCs) were procured before and 1 hour after the administration of IFN-a and analyzed for the presence of phosphorylated STAT1 (P-STAT1) and P-STAT2 by intracellular flow cytometric analysis and the induction of interferon stimulated gene (ISG) transcripts by Real Time PCR. Results: P-STAT1 in response to 5 MU/m^2 IFN-a was higher than that for the 10 MU/m^2 dose (p = 0.0617). The 5 MU/m^2 dose also led to a greater activation of STAT2 (p = 0.0388). The induction of interferon stimulated genes (ISGs; IFIT1, IFIT2, OAS3) within PBMCs was not enhanced following the increase in IFN-a dose to 10 MU/m^2 at 2 weeks although inhibitors of IFN-a-signaling (SOCS1 and SOCS3) were activated to a greater degree. In addition, microarray analysis was performed on 4 patients and revealed that only one of 36 interferon regulated genes was expressed to a greater extent following treatment with 10 MU/m^2 IFN-a as compared to 5 MU/m^2. Conclusions: These results suggest that 5 MU/m^2 of IFN-a are as effective as higher doses with respect to the induction of STAT signal transduction and ISGs within immune effector cells.

No significant financial relationships to disclose.

Detection of a novel Borna disease virus-encoded 10 kDa protein in infected cells and tissues

Borna disease (BD) is a transmissible, progressive polioencephalomyelitis primarily of horses and sheep. The genomes of two cell-adapted strains of Borna disease virus (BDV), the aetiological agent of BD, have been cloned and sequenced. According to the structural characterization achieved so far, BDV contains a non-segmented negative-sense 8.9 kb single-stranded RNA genome. In this paper we report the expression, purification and intracellular tracing of a novel non-glycosylated BDV-specific protein with a molecular mass of approximately 10 kDa (BDV p10 protein). The successful isolation of the corresponding mRNA from infected cells, amplification of the genetic region by RT-PCR and its efficient expression as a glutathione S-transferase (GST) fusion protein demonstrated that antibodies specific for the BDV p10 protein are induced in infected animals. In addition, we have produced monospecific antisera against the GST-p10 fusion protein in rabbits. This monospecific antiserum recognized the BDV p10 protein in brain cells of naturally and experimentally infected animals as well as in persistently BDV-infected cells. Antibody-mediated affinity-chromatography using the anti-p10 serum could successfully be applied to purify a ca. 10 kDa antigen from infected animal cells to such an extent that glycosylation of this component could be ruled out.

Combined amplification and sequencing in a single reaction using two DNA polymerases with differential incorporation rates for dideoxynucleotides

We describe an approach, which combines the process of DNA amplification and sequence determination by using a pair of primers and two DNA polymerases with different incorporation rates for dideoxynucleotides. The process of target sequence amplification is carried out by the DNA polymerase with a low dideoxynucleotide incorporation rate while its polymerase counterpart with a high incorporation rate generates a sequence ladder. The needs for separate amplification via polymerase chain reaction (PCR) or cloning into plasmids including the respective purification steps therefore can be avoided. In addition, the use of dye terminator chemistry enables the simultaneous generation of forward and reverse sequence ladders, which can be separated based on the streptavidin-biotin system when one amplification primer is biotinylated.

A filtration method for plasmid isolation using microtiter filter plates

A method for the simultaneous isolation of plasmid DNA from as many as 96 Escherichia coli clones in less than 2 h is described. It is based on a modified version of the alkaline lysis procedure originally described by Birnboim and Doly (Nucleic Acids Res. 7, 1513-1523, 1979). The handling of DNA samples is facilitated by the use of microtiter plates with membrane filter bottoms. All centrifugation steps are replaced by filtrations ("the filtration method"). The yield of plasmid DNA from 0.35 ml of an overnight culture is sufficient for restriction analysis of the plasmid clones. Up to 400 nucleotides' readable sequences could be obtained in cycle sequencing reactions with an unmodified sequencing protocol on an automated ABI sequencer.

OmpA-FMDV VP1 fusion proteins: production, cell surface exposure and immune responses to the major antigenic domain of foot-and-mouth disease virus

Exposure at the bacterial outer surface of the major antigenic epitope of the foot-and-mouth disease (FMDV) viral protein VP1 was studied using protein fusion with outer membrane protein A (OmpA) of Shigella dysenteriae for production and transport of the foreign polypeptide to the outer membrane of Escherichia coli. Fusion constructs with VP1 peptide insertions of up to 56 amino acids in the third outer domain of OmpA could be demonstrated on the bacterial surface by indirect immunofluorescence and immunogold labelling. OmpA fusion proteins with large insertions from sequences of the FMDV protein VP1 were shown to elicit virus-specific immune responses in rabbits.

[Circular neovascularization of the circulus arteriosus iridis minor]

Vessel duplications of the anastomosis of the cirulus arteriosus iridis minor were observed in 15 patients with diabetes mellitus and in four patients with retinal venous occlusion, in a total of 1192 iris angiograms made. In each of these cases there is a bilateral neo-vascularization that may be regarded as an indication of a general vascular disease. It could be a fairly unaggressive process of new vessel formation in the iris which, during four years of observation, has in none of the cases observed developed into a rubeosis iridis visible under the slit lamp.