Cryoballoon ablation of left atrial roof with a novel cryoballoon system

Introduction

A novel cryoballoon system (POLARx) has emerged and its efficacy regarding pulmonary vein isolation (PVI) has been already investigated. On the other hand, cryoballoon ablation of left atrial (LA) roof has been performed using a conventional cryoballoon system (Arctic Front Advance Pro [AFA-Pro]) in addition to PVI. However, cryoballoon ablation of LA roof with POLARx has not been investigated yet.

Methods

We performed cryoballoon ablation of LA roof with POLARx in 22 patients after we achieved PVI. After the cryoballoon ablation, complete conduction block at LA roof and isolation of all PVs were confirmed by creating an activation map during high right atrium pacing. If they could not be obtained with solely a cryoballoon, touch up ablation with radiofrequency ablation was permitted. The procedural data during ablation with POLARx was compared with those during ablation with AFA-Pro we had performed in a historical cohort of patients (n=46).

Results

Complete conduction block at LA roof without touch up ablation could be obtained in all the patients in POLARx group and 44 (95.7%) patients in AFA-Pro group. Total procedure time was almost similar in both groups (164.2±35.4 min for POLARx vs 180.3±35.4 min for AFA-Pro, p=0.10). During LA roof line ablation, nadir balloon temperature was significantly lower in POLARx group (right side: −53.6±4.4°C for POLARx vs −45.6±4.6°C for AFA-Pro, p<0.01, central part: −56.4±4.3°C for POLARx vs −46.0±3.7°C for AFA-Pro, p<0.01, left side: −55.1±3.5°C for POLARx vs −45.7±5.3°C for AFA-Pro, p<0.01), and balloon temperature reached −40°C earlier in POLARx (right side: 30.7±8.9 sec for POLARx vs 78.0±39.8 sec for AFA-Pro, p<0.01, central part: 30.6±9.3 sec for POLARx vs 65.9±33.3 sec for AFA-Pro, p<0.01, left side: 30.4±4.2 sec for POLARx vs 78.8±49.6 sec for AFA-Pro, p<0.01). Total freezing time required for LA roof line ablation was significantly shorter in POLARx group (589.3±163.6 sec for POLARx vs 877.5±191.7 sec for AFA-Pro, p<0.01).The scar area created after LA roof line ablation was similar in both groups (9.3±4.1 cm2 for POLARx vs 11.0±4.8 cm2 for AFA-Pro, p=0.23).

Conclusion

Complete conduction block at LA roof could be obtained after cryoballoon ablation with POLARx, in the same way as AFA-Pro. Lower nadir balloon temperature could be expected in shorter freezing time during LA roof line ablation in using POLARx compared with AFA-Pro.

Funding Acknowledgement

Type of funding sources: None.

How to perform effective cryoballooon ablation of left atrial roof: considerations after experiences of more than 1000 cases

Introduction

Although pulmonary vein isolation is the cornerstone of atrial fibrillation (AF) ablation, concomitant cryoballoon ablation of left atrial (LA) roof has been expected to improve clinical outcomes after ablation. We demonstrate characteristics and efficacy of cryoballoon ablation of LA roof through our experiences from a large volume of procedures.

Methods

We had performed cryoballoon ablation of LA roof in 1036 procedures including 202 redo procedures in AF patients since June 2016. Among these procedures, we analyzed 834 patients (309 paroxysmal AF) who had undergone de novo ablation for AF. We confirmed whether the complete conduction block of LA roof line was obtained after the ablation.

Results

LA roof line block was obtained in 767 patients (92.0%) without touch up ablation with a radiofrequency catheter (Group A). LA diameter (LAD) was significantly smaller (43.6±6.6mm vs 47.4±7.5mm, p<0.01) and body mass index (BMI) was significantly lower (24.9±4.0kg/m2 vs 26.3±4.6kg/m2, p=0.01) in those in Group A compared with those without LA roof line block after cryoballoon ablation (Group B). Compared with those in Group B, cryoballoon application number of LA roof (4.1±1.2 vs 4.5±1.6, p<0.01) and mean nadir of cryoballoon temperature during cryoballoon ablation of LA roof (−44.5±5.6°C vs −40.5±7.5°C, p<0.01) were significantly lower in those in Group A. Regarding cryoballoon application number, the number of the cryoballoon application in which a cryoballoon was applied to LA roof with the guiding catheter located in a left superior pulmonary vein (LSPV) was significantly lower in patients in Group A (1.3±0.8 vs 1.6±1.0, p=0.02), and when the number was less than 2, mean nadir of cryoballoon temperature was significantly lower compared with when it was 2 or more than 2 (−44.8±5.8°C vs −42.8±5.6°C, p<0.01). Among those refer to first ablation procedures, one-year Kaplan-Meier atrial arrhythmias free rate estimates, 80.6% for those in Group A and 59.0% for those in Group B (p<0.01). Multivariate analysis identified LA roof line block without touch up ablation as one of the predictors of atrial arrhythmias recurrences. Atrial tachycardia depending on LA roof occurred after cryoballoon ablation of LA roof in 8 patients, although LA roof line block without touch up ablation could be obtained in the index ablation procedure in 6 patients among them.

Conclusion

LA roof line block could be obtained by solely cryoballoon with a reasonable success rate, especially in those with smaller LAD and lower BMI. To obtaine LA roof line block, cryoballoon ablation with the guiding catheter located in LSPV is preferable. LA roof line block without touch up ablation brings better clinical outcomes in those who underwent cryoballoon ablation of LA roof.

Funding Acknowledgement

Type of funding sources: None.

Nosocomial infection by human bocavirus and human rhinovirus among paediatric patients with respiratory risks

BACKGROUND

Nosocomial infections by respiratory viruses undetected by rapid tests are not often diagnosed. For paediatric patients with background diseases, nosocomial infection could be fatal.

AIM

To determine the relationship between developing symptoms by respiratory viruses undetectable by rapid tests and respiratory risks and to improve the management of infection control.

METHODS

Two episodes of nosocomial infection by human bocavirus (HBoV) and human rhinovirus (HRV) were retrospectively investigated in a tertiary hospital paediatric ward in Japan. Viruses were identified by polymerase chain reaction to determine infection control management. When viruses of the same species were detected from different patients, the virus homology was investigated. The relationship between respiratory risks and developing symptoms was statistically investigated.

FINDINGS

Three and four patients with respiratory risks in the HBoV and HRV outbreaks, respectively, developed respiratory symptoms. The nucleotide sequences of two patients in the HBoV outbreak and all four patients in the HRV outbreak were phylogenetically close. In both outbreaks, the patients with respiratory risks developed significantly more symptoms than those without any risk (P = 0.035 and 0.018, respectively). After the patients with respiratory infection were separated from those with respiratory risks, no additional nosocomial infection occurred.

CONCLUSION

Patients with respiratory risks easily develop respiratory symptoms and acquire severe symptoms of nosocomial infection by those viruses. In a paediatric ward, we should adopt not only standard precautions but also isolation management of the patients with respiratory symptoms, even if they have negative results in rapid tests.

Balance of Emission and Dynamical Controls on Ozone During the Korea-United States Air Quality Campaign From Multiconstituent Satellite Data Assimilation

Global multiconstituent concentration and emission fields obtained from the assimilation of the satellite retrievals of ozone, CO, NO2, HNO3, and SO2 from the Ozone Monitoring Instrument (OMI), Global Ozone Monitoring Experiment 2, Measurements of Pollution in the Troposphere, Microwave Limb Sounder, and Atmospheric Infrared Sounder (AIRS)/OMI are used to understand the processes controlling air pollution during the Korea-United States Air Quality (KORUS-AQ) campaign. Estimated emissions in South Korea were 0.42 Tg N for NO x and 1.1 Tg CO for CO, which were 40% and 83% higher, respectively, than the a priori bottom-up inventories, and increased mean ozone concentration by up to 7.5 ± 1.6 ppbv. The observed boundary layer ozone exceeded 90 ppbv over Seoul under stagnant phases, whereas it was approximately 60 ppbv during dynamical conditions given equivalent emissions. Chemical reanalysis showed that mean ozone concentration was persistently higher over Seoul (75.10 ± 7.6 ppbv) than the broader KORUS-AQ domain (70.5 ± 9.2 ppbv) at 700 hPa. Large bias reductions (>75%) in the free tropospheric OH show that multiple-species assimilation is critical for balanced tropospheric chemistry analysis and emissions. The assimilation performance was dependent on the particular phase. While the evaluation of data assimilation fields shows an improved agreement with aircraft measurements in ozone (to less than 5 ppbv biases), CO, NO2, SO2, PAN, and OH profiles, lower tropospheric ozone analysis error was largest at stagnant conditions, whereas the model errors were mostly removed by data assimilation under dynamic weather conditions. Assimilation of new AIRS/OMI ozone profiles allowed for additional error reductions, especially under dynamic weather conditions. Our results show the important balance of dynamics and emissions both on pollution and the chemical assimilation system performance.

STAT6 and IL-10 are required for the anti-arthritic effects of Schistosoma mansoni via different mechanisms

To investigate possible roles of T helper type 2 (Th2) cytokines in the anti-arthritic effects of a blood fluke, Schistosoma mansoni (Sm), for mouse collagen-induced arthritis (CIA), wild-type (WT), signal transducer and activator of transcription 6 (STAT6) knock-out (KO) and interleukin (IL)-10 KO mice were infected with Sm. Three weeks after infection, the mice were immunized with bovine type II collagen (IIC). Arthritis severity was monitored by scoring, measurement of paw thickness and the presence of ankylosis. Serum anti-IIC IgG levels, splenic cytokine production and cytokine gene expression in the popliteal lymph nodes (PLNs) were measured and compared among WT and gene-KO mice. Consistent with our previous findings, Sm infection reduced the arthritis severity in WT mice. Splenic production of IL-17A and tumor necrosis factor (TNF)-α was reduced by the infection. In contrast, Sm infection markedly exacerbated CIA in STAT6 KO mice. In the KO mice, IL-17A production was increased by the infection. Conversely, Sm infection did not affect the exacerbated arthritis in IL-10 KO mice, although IL-17A production was reduced by the helminth. Our results suggest that signaling via STAT6 (presumably IL-4 and/or IL-13) and IL-10 is required for the suppression of CIA by Sm infection, but through different mechanisms. STAT6 was essential for helminth-induced reduction of IL-17A, whereas regulation of the basal arthritis severity by IL-10 was needed in order for it to be sufficiently suppressed by the helminth.

Thy28 protects against anti-CD3-mediated thymic cell death in vivo

Apoptotic cell death plays a pivotal role in the development and/or maintenance of several tissues including thymus. Deregulated thymic cell death is associated with autoimmune diseases including experimental autoimmune encephalomyelitis (EAE), a prototype murine model for analysis of human multiple sclerosis. Because Thy28 expression is modulated during thymocyte development, we tested whether Thy28 affects induction of EAE as effectively as antigen-induced thymocyte deletion using Thy28 transgenic (TG) mice. Thy28 TG mice showed partial resistance to anti-CD3 monoclonal antibody (mAb)-induced thymic cell death in vivo, as assessed by annexin V-expression and loss of mitochondrial membrane potential. The resistance to anti-CD3 mAb-induced cell death in Thy28 TG mice appeared to correlate with a decreased c-Jun N-terminal kinase phosphorylation and reduced down-regulation of Bcl-xL. Moreover, thymic hyperplasia was detected in Thy28 TG mice, although thymocyte development was unaltered. Development of peripheral lymphoid tissues including spleen and lymph nodes was also unaltered. Thy28 TG spleen T cells showed an increased production of IFN-γ, but not IL-17, in response to both anti-CD3 and anti-CD28 mAbs. Finally, Thy28 TG mice displayed accelerated induction of EAE as assessed by disease incidence, clinical score, and pathology following immunization with myelin oligodendrocyte glycoprotein compared with control WT mice. These findings suggest that modulation of Thy28 expression plays a crucial role in the determination of thymic cell fate, which may contribute to the development of EAE through proinflammatory cytokine production.