Catheter-based pulmonary vein isolation fails to prevent transient atrial arrhythmogenic changes related to acute obstructive respiratory events in a porcine model

AIMS

Pulmonary vein isolation (PVI) is the corner stone of modern rhythm control strategies in patients with atrial fibrillation (AF). Sleep-disordered breathing (SDB) is prevalent in more than 50% of patients undergoing AF ablation and studies have indicated a greater recurrence rate after PVI in patients with SDB. Herein, we study the effect of catheter-based PVI on AF in a pig model for SDB.

METHODS AND RESULTS

In 11 sedated spontaneously breathing pigs, obstructive apnoeas were simulated by 75 seconds of intermittent negative upper airway pressure (INAP) applied by a negative pressure device connected to the endotracheal tube. INAPs were performed before and after PVI. AF-inducibility and atrial effective refractory periods (aERP) were determined before and during INAP by programmed atrial stimulation. PVI prolonged the aERP by 48 ± 27 ms in the right atrium (RA) (p < 0.0001) and by 40 ± 34 ms in the left atrium (LA) (p = 0.0004). Following PVI, AF-inducibility dropped from 28 ± 26% to 0% (p = 0.0009). INAP was associated with a transient aERP-shortening (ΔaERP) in both atria, which was not prevented by PVI (INAP indued ΔaERP after PVI in the RA: -57 ± 34 ms, p = 0.0002; in the LA: -42 ± 24 ms, p < 0.0001). INAP was associated with a transient increase in AF-inducibility (from 28 ± 26% to 69 ± 21%; p = 0.0008), which was not attenuated by PVI (INAP-associated AF-inducibility after PVI: 58 ± 33% (p = 0.5)).

CONCLUSION

Transient atrial arrhythmogenic changes related to acute obstructive respiratory events are not prevented by electrical isolation of the pulmonary veins, which partially explains the increased AF recurrence in patients with SDB after PVI procedures.

Lower Recurrence Rates of Atrial Fibrillation and MACE Events After Early Compared to Late Ablation: A Danish Nationwide Register Study

BACKGROUND

Guidelines recommend prioritizing treatment with antiarrhythmic drugs before referral of patients with atrial fibrillation to ablation, delaying a potential subsequent ablation. However, delaying ablation may affect ablation outcomes. We sought to investigate the impact of duration from diagnosis to ablation on the risk of atrial fibrillation recurrence and adverse events.

METHODS AND RESULTS

Using Danish nationwide registries, all patients with first-time ablation for atrial fibrillation were identified and included from 2010 to 2018. Patients were divided into 4 groups by diagnosis-to-ablation time: <1.0 year (early ablation), 1.0 to 1.9 years, 2.0 to 2.9 years, and >2.9 years (late ablation). The primary end point was atrial fibrillation recurrence after the 90-day blanking period, defined by admission for atrial fibrillation, cardioversions, use of antiarrhythmic drugs, or repeat atrial fibrillation ablations. The secondary end point was a composite end point of heart failure, ischemic stroke, or death, and each event individually. The study cohort consisted of 7705 patients. The 5-year cumulative incidence of atrial fibrillation recurrence in the 4 groups was 42.9%, 54.8%, 55.9%, and 58.4%, respectively. Hazard ratios were 1.20 (95% CI, 1.07-1.35), 1.29 (95% CI, 1.13-1.47), and 1.40 (95% CI, 1.28-1.53), respectively, with the early ablation group as reference. The hazard ratio for the combined secondary end point was 1.22 (95% CI, 1.04-1.44) in the late ablation group compared with the early ablation group.

CONCLUSIONS

In patients undergoing ablation for atrial fibrillation, early ablation was associated with a significantly lower risk of atrial fibrillation recurrence. Furthermore, the associated risk of heart failure, ischemic stroke, or death was significantly lower in early-compared with late-ablation patients.

Systematic review of the patient burden of generalised myasthenia gravis in Europe, the Middle East, and Africa

BACKGROUND

Myasthenia gravis (MG) is a rare autoimmune disease characterised by muscle weakness, and progression from ocular (oMG) to generalised (gMG) symptoms results in a substantial negative impact on quality of life (QoL). This systematic review aimed to provide an overview of the patient burden experienced by people living with gMG.

METHODS

Electronic database searches (conducted March 2022), supplemented by interrogation of grey literature, were conducted to identify studies reporting patient burden outcomes in patients with gMG in Europe, the Middle East and Africa. Results were synthesised narratively due to the heterogeneity across trials.

RESULTS

In total, 39 patient burden publications (representing 38 unique studies) were identified as relevant for inclusion in the systematic review, consisting of 37 publications reporting formal patient-reported outcome measures (PROMs), and two publications describing alternative qualitative assessments of patient experience. The studies included a variety of measures including generic and disease-specific PROMs, as well as symptom-specific PROMs focusing on key comorbidities including depression, anxiety, fatigue and sleep disturbance. The findings showed some variation across studies and PROMs; however, in general there was evidence for worse QoL in patients with gMG than in healthy controls or in patients with oMG, and a trend for worsening QoL with increasing MG severity.

CONCLUSIONS

This review highlights the importance of considering patient QoL when developing and assessing treatment and management plans for patients with gMG. However, the heterogeneity identified across studies illustrates the need for further representative and well-powered studies in large cohorts administering consistent, validated questionnaires.

TRIAL REGISTRATION

The protocol for this systematic review was registered in PROSPERO: CRD42022328444.

A mechanically validated open-source silicone model for the training of gastric perforation sewing

BACKGROUND

Gastrointestinal perforation is commonly seen in emergency departments. The perforation of the stomach is an emergency situation that requires immediate surgical treatment. The necessary surgical skills require regular practical training. Owing to patient`s safety, in vivo training opportunities in medicine are restricted. Animal tissue especially porcine tissue, is commonly used for surgical training. Due to its limiting factors, artificial training models are often to be preferred. Many artificial models are on the market but to our knowledge, none that mimic the haptic- and sewing properties of a stomach wall at the same time. In this study, an open source silicone model of a gastric perforation for training of gastric sewing was developed that attempts to provide realistic haptic- and sewing behaviour.

METHODS

To simulate the layered structure of the human stomach, different silicone materials were used to produce three different model layups. The production process was kept as simple as possible to make it easily reproducible. A needle penetration setup as well as a systematic haptic evaluation were developed to compare these silicone models to a real porcine stomach in order to identify the most realistic model.

RESULTS

A silicone model consisting of three layers was identified as being the most promising and was tested by clinical surgeons.

CONCLUSIONS

The presented model simulates the sewing characteristics of a human stomach wall, is easily reproducible at low-costs and can be used for practicing gastric suturing techniques.

TRIAL REGISTRATIONS

Not applicable.

Endo- and epicardial mapping of spontaneous ventricular fibrillation during acute myocardial infarction in a porcine model

Introduction

Ventricular fibrillation (VF) during the first minutes of acute myocardial infarction (AMI) is among the most frequent causes of sudden cardiac death. Albeit mechanisms for arrhythmogenesis during ischemia are well understood on a cellular level, little is known in an in-vivo setting.

Aim

Aim of this study was the development and characterization of a porcine model of AMI and spontaneous VF with continuous electrical mapping using a non-contact mapping system (EnSite Array) in the left ventricle (LV) and an electrode sock covering the whole heart. Activation-recovery intervals (ARI), beat-to-beat variation in repolarization (BVR), and ectopic activation were measured.

Methods

Nineteen Danish Landrace pigs (56±4 kg, heart weight 251±20 g) were anaesthetized, equipped with electrophysiological (EP) catheters in the coronary sinus, right and LV as well as a multi electrode array (St. Jude, EnSite Array) catheter in the LV. Thoracotomy was performed and the sock electrode was placed on the pericardium covering the anterior and the posterior surface of the heart. Finally, the mid-left anterior descendent artery was occluded with a percutaneous transluminal coronary angioplasty balloon to induce AMI and kept in place for 45 minutes followed by 20 minutes of reperfusion. Data from both systems were analyzed offline using a custom-made software.

Results

All pigs had stable hemodynamic parameters during the procedure. Spontaneous VF occurred in 8/19 pigs during the occlusion period. Epi- and endocardial mapping showed similar shortening of ARI in the infarcted area (Figure 1A). AMI shortened ARI in the ischemic area to a greater extend in pigs that developed VF (Figure 1B) and caused beat-to-beat variation in repolarization (BVR) in later phases (Figure 1C). Ectopic beats proceeding spontaneous VF varied in activation site and subsequent repolarization (Figure 1D, left). Multiple short-coupled ectopic beats destabilized the electrical substrate further and led to progressive ARI shortening (Figure 1D, last 4 beats).

Conclusion

We present the first whole heart mapping experiments of spontaneous VF during AMI with endo- and epicardial mapping. Pigs with VF had shorter ARI, greater dispersion but similar BVR during AMI compared to those without VF. These findings provide a deeper understanding of arrhythmogenesis during AMI and can help to develop new antiarrhythmic drugs or to assess risk factors of VF.

Funding Acknowledgement

Type of funding sources: None.

Inhibition of Small-Conductance Calcium-Activated Potassium Current (I K,Ca) Leads to Differential Atrial Electrophysiological Effects in a Horse Model of Persistent Atrial Fibrillation

Background

Small-conductance Ca²⁺-activated K⁺ (K_Ca2) channels have been proposed as a possible atrial-selective target to pharmacologically terminate atrial fibrillation (AF) and to maintain sinus rhythm. However, it has been hypothesized that the importance of the K_Ca2 current—and thereby the efficacy of small-conductance Ca²⁺-activated K⁺ current (I_K,Ca) inhibition—might be negatively related to AF duration and the extent of AF-induced remodeling.

Experimental Approach and Methods

To address the hypothesis of the efficacy of I_K,Ca inhibition being dependent on AF duration, the anti-arrhythmic properties of the I_K,Ca inhibitor NS8593 (5 mg/kg) and its influence on atrial conduction were studied using epicardial high-density contact mapping in horses with persistent AF. Eleven Standardbred mares with tachypacing-induced persistent AF (42 ± 5 days of AF) were studied in an open-chest experiment. Unipolar AF electrograms were recorded and isochronal high-density maps analyzed to allow for the reconstruction of wave patterns and changes in electrophysiological parameters, such as atrial conduction velocity and AF cycle length. Atrial anti-arrhythmic properties and adverse effects of NS8593 on ventricular electrophysiology were evaluated by continuous surface ECG monitoring.

Results

I_K,Ca inhibition by NS8593 administered intravenously had divergent effects on right and left AF complexity and propagation properties in this equine model of persistent AF. Despite global prolongation of AF cycle length, a slowing of conduction in the right atrium led to increased anisotropy and electrical dissociation, thus increasing AF complexity. In contrast, there was no significant change in AF complexity in the LA, and cardioversion of AF was not achieved.

Conclusions

Intra-atrial heterogeneity in response to I_K,Ca inhibition by NS8593 was observed. The investigated dose of NS8593 increased the AF cycle length but was not sufficient to induce cardioversion. In terms of propagation properties during AF, I_K,Ca inhibition by NS8593 led to divergent effects in the right and left atrium. This divergent behavior may have impeded the cardioversion success.

Association of common genetic variants related to atrial fibrillation and the risk of ventricular fibrillation in the setting of first ST-elevation myocardial infarction

Background

Cohort studies have revealed an increased risk for ventricular fibrillation (VF) and sudden cardiac death (SCD) in patients with atrial fibrillation (AF). In this study, we hypothesized that single nucleotide polymorphisms (SNP) previously associated with AF may be associated with the risk of VF caused by first ST-segment elevation myocardial infarction (STEMI).

Methods

We investigated association of 24 AF-associated SNPs with VF in the prospectively assembled case–control study among first STEMI-patients of Danish ancestry.

Results

We included 257 cases (STEMI with VF) and 537 controls (STEMI without VF). The median age at index infarction was 60 years for the cases and 61 years for the controls (p = 0.100). Compared to the control group, the case group was more likely to be male (86% vs. 75%, p = 0.001), have a history of AF (7% vs. 2%, p = 0.006) or hypercholesterolemia (39% vs. 31%, p = 0.023), and a family history of sudden death (40% vs. 25%, p < 0.001). All 24 selected SNPs have previously been associated with AF. None of the 24 SNPs were associated with the risk of VF after adjustment for age and sex under additive genetic model of inheritance in the logistic regression model.

Conclusion

In this study, we found that the 24 AF-associated SNPs may not be involved in increasing the risk of VF. Larger VF cohorts and use of new next generation sequencing and epigenetic may in future identify additional AF and VF risk loci and improve our understanding of genetic pathways behind the two arrhythmias.

Cellulose nanocrystals by acid vapour: towards more effortless isolation of cellulose nanocrystals

Cellulose nanocrystals (CNCs) are topical in materials science but their full potential is yet to be fulfilled because of bottlenecks in the production: the process consumes huge amounts of water, recycling the strong acid catalyst is difficult, and purification steps are cumbersome, particularly with lengthy dialysis. Production of CNCs with HCl vapour overcomes many of these difficulties but the dispersion of CNCs from the already hydrolysed fibre matrix is a formidable challenge. This study is a fundamental effort to explore very basic means to facilitate CNC dispersion from cotton linter fibres (filter paper), hydrolysed to levelling off degree of polymerization by HCl vapour. The introduction of carboxylic groups on the cellulose crystal surface proved the most efficient method to alleviate dispersion with good yields (ca. 50%) and a provisional possibility to tune the CNC length. By contrast, attempts to directly disperse untreated hydrolysed fibres in various organic solvents and aqueous surfactant solutions were unsuccessful. The results showed that hydrolysis of native cellulose fibres by HCl vapour is indeed a viable method for producing CNCs but it has more potential as a pre-treatment step rather than a full-fledged process on its own.

One-year clinical outcome after ablation with a novel multipolar irrigated ablation catheter for treatment of atrial fibrillation: potential implications for clinical use

AIMS

Pulmonary vein isolation (PVI) is an established therapy for atrial fibrillation (AF). However, PVI remains a time-consuming procedure. A novel multipolar irrigated radiofrequency (RF) ablation catheter (nMARQ™) is aiming to improve PVI. We investigated the influence on procedural parameters and assessed clinical outcomes after PVI using this novel catheter.

METHODS AND RESULTS

Fifty-eight consecutive patients with paroxysmal AF were equally allocated (n = 29/group) to PVI treatment with (i) the novel multipolar ablation catheter (nMARQ™) and (ii) a standard single-tip ablation catheter (SAC). Study endpoints included procedure time, fluoroscopy time, radiation dose, RF time, number of energy applications, and clinical outcome defined as freedom from AF after a single procedure. Successful PVI was confirmed by a separate circular, multipolar mapping catheter in all patients treated with the nMARQ™. Pulmonary vein isolation was achieved in 100% in the SAC group. In the nMARQ™ group, PVI was suggested in all patients. However, confirmatory mapping revealed persistent pulmonary vein (PV) conduction in 19 out of 29 nMARQ™ patients. These patients underwent further ablation, which still failed to achieve PVI in 5 of the 29 nMARQ™ patients, mainly due to significant temperature rise in the oesophagus and device-related limitations reaching the right inferior PV. Mean fluoroscopy time (31 ± 12 vs. 23 ± 10 min, P < 0.05) and (132 ± 37 vs. 109 ± 30 min, P < 0.05) were longer in nMARQ™ vs. SAC patients. Radiofrequency time was shorter in nMARQ™ vs. SAC group (21 ± 9 vs. 35 ± 12 min, P < 0.001). Radiation dose and the number of energy applications did not differ between both groups. Clinical outcome analysis revealed no significant differences (nMARQ™: 72 vs. SAC: 72%) after a mean follow-up of 373 ± 278 days.

CONCLUSION

The use of the nMARQ™ catheter is associated with important device-related limitations to achieve successful PVI. However, clinical outcomes were equivalent in nMARQ™- and SAC-treated patients.

Percutaneous extracorporeal life support for patients in therapy refractory cardiogenic shock: initial results of an interdisciplinary team

OBJECTIVES

Therapy refractory cardiogenic shock is associated with dismal outcome. Percutaneous implantation of an extracorporeal life support (ECLS) system achieves immediate cardiopulmonary stabilization, sufficient end-organ perfusion and reduction of subsequent multiorgan failure (MOF).

METHODS

Forty-one patients undergoing percutaneous ECLS implantation for cardiogenic shock from February 2012 until August 2013 were retrospectively analysed. Mean age was 52 ± 13 years, 6 (15%) were female. Mean pH values obtained before ECLS implantation were 7.15 ± 0.24, mean lactate concentration was 11.7 ± 6.4 mmol/l. Levels obtained 6 h after ECLS implantation were 7.30 ± 0.14 and 8.7 ± 5.0 mmol/l, respectively. In 23 patients (56%) cardiogenic shock resulted from an acute coronary syndrome in 13 (32%) from cardiomyopathy, in 5 (12%) from other causes. Twenty-seven (66%) had been resuscitated, in 14 (34%) implantation was performed under ongoing cardiopulmonary resuscitation (CPR). Of note, 97% of the acute coronary syndrome patients underwent percutaneous coronary intervention (PCI) either before ECLS implantation or under ECLS support. Extracorporeal life support implantation was performed on scene (Emergency Department, Cath Lab, Intensive Care Unit) by a senior cardiac surgeon and a trained perfusionist, in 8 cases (20%) in the referring hospital.

RESULTS

Thirty-day mortality was 51% [21 patients, due to MOF (n = 14), cerebral complications (n = 6) and heart failure (n = 1)]. Logistic regression analysis identified 6-h pH values as an independent risk factor of 30-day mortality (P < 0.001, OR = 0.000, 95% CI 0.000-0.042). Neither CPR nor implantation under ongoing CPR resulted in significant differences. In 26 cases (63%), the ECLS system could be explanted, after mean support of 169 ± 67 h. Seven of these patients received cardiac surgery [ventricular assist device implantation (n = 4), heart transplantation (n = 1), other procedures (n = 2)].

CONCLUSIONS

Due to the evolution of transportable ECLS systems and percutaneous techniques implantation on scene is feasible. Extracorporeal life support may serve as a bridge-to-decision and bridge-to-treatment device. Neurological evaluation before ventricular assist device implantation and PCI under stable conditions are possible. Despite substantial mortality, ECLS implantation in selected patients by an experienced team offers additional support to conventional therapy as well as CPR and allows survival in patients that otherwise most likely would have died. This concept has to be implemented in cardiac survival networks in the future.

The human C-type lectin-like receptor CLEC-1 is upregulated by TGF-β and primarily localized in the endoplasmic membrane compartment

The orphan receptor CLEC-1 is part of a subfamily of C-type lectin-like receptors, which is encoded in the human natural killer gene complex and comprises several pattern recognition receptors important for innate immune functions. As information on human CLEC-1 is still very limited, we aimed to further characterize this receptor. Similar to another subfamily member, LOX-1, expression of CLEC-1 mRNA was detected in myeloid cells as well as in endothelial cells. CLEC-1 protein displayed N-linked glycosylation and formed dimers. However, in contrast to other members of the subfamily, expression levels were upregulated by transforming growth factor (TGF)-β, but not significantly affected by proinflammatory stimuli. It is intriguing that human CLEC-1 could only be detected intracellularly with a staining pattern resembling endoplasmic reticulum proteins. Neither TGF-β nor inflammatory stimuli could promote significant translocation to the cell surface. These findings are in accordance with a primarily intracellular localization and function of human CLEC-1.

Tumescent liposuction in Germany: history and new trends and techniques

Due to the developments and changes of tumescent solution, infiltration technique, and cannulas, we perform tumescent liposuction today using up to 6-8 l tumescent solution. Total aspirate measures up to 9 l, pure fat aspired up to 5 l. Tumescent liposuction of extended areas can still be done as an outpatient procedure. The condition of patients intra- and postoperatively as well as results has improved and the predictability of outcome is more certain.

Binding, uptake, and transport of hypericin by Caco-2 cell monolayers

The biological evaluation of hypericin in various test models is hampered by its very poor water solubility. In the present study cyclodextrin formulations and liposomal preparations were investigated for improved delivery and solubility of hypericin in aqueous buffer systems. Caco-2 cells, grown to tight monolayers on 96-well tissue culture plates as well as on Transwell polycarbonate filters, were used to study the membrane binding and the epithelial transport of hypericin. Cumulative transport of hypericin, which could not be measured without the use of cyclodextrins, in apical-to-basolateral direction from cyclodextrin-hypericin buffer solutions was 3-5% at 37 degrees C and approximately 0.12% at 4 degrees C after 5 h. After an incubation time of 1 h at 37 and 4 degrees C, 12.7% +/- 2.6% and 6.5% +/- 0.8%, respectively, of hypericin were found to be bound to or taken up by Caco-2 cells. Liposomal formulations markedly increased the solubility of hypericin in Krebs-Ringer buffer, but there was no effect observed on the binding and transport of hypericin delivered by liposomes in the Caco-2 cell model. Due to the fluorescence properties of hypericin, its interaction with the cells could be visualized by confocal laser scanning microscopy. The results indicate that a significant accumulation of the drug in the cell membrane and the cell nucleus membrane takes place. We conclude that hypericin is absorbed through the intestinal epithelium by passive transcellular diffusion and that increasing its solubility by cyclodextrin appears as a promising approach to increase its oral bioavailability for pharmaceutical formulations.