Junctional rhythm during cryoablation for typical atrioventricular nodal reentrant tachycardia.

INTRODUCTION: Cryoablation is being used as an alternative to radiofrequency (RF) ablation for atrioventricular nodal reentrant tachycardia (AVNRT) owing to the lower risk of atrioventricular block (AVB) compared to RF ablation. Junctional rhythm often occurs during successful application of RF ablation for AVNRT. In contrast, junctional rhythm has rarely been reported to occur during cryoablation. This retrospective study evaluated the characteristics of junctional rhythm during cryoablation for typical AVNRT. METHODS AND RESULTS: This retrospective study included 127 patients in whom successful cryoablation of typical AVNRT was performed. Patients diagnosed with atypical AVNRT were excluded. Junctional rhythm appeared during cryofreezing in 22 patients (17.3%). These junctional rhythms appeared due to cryofreezing at the successful site in the early phase within 15 s of commencement of cooling. Transient complete AVB was observed in 10 of 127 patients (7.9%), and it was noted that atrioventricular conduction improved immediately after cooling was stopped in these 10 patients. No junctional rhythm was observed before the appearance of AVB. No recurrence of tachycardia was confirmed in patients in whom junctional rhythm occurred by cryofreezing at the successful site. CONCLUSION: Occurrence of junctional rhythms during cryoablation is not so rare and can be considered a criterion for successful cryofreezing. Furthermore, junctional rhythm may be associated with low risk of recurrent tachycardia.

Antithrombotic Regimen After Percutaneous Left Atrial Appendage Closure　- A Real-World Study.

BACKGROUND: Antithrombotic therapy after left atrial appendage closure (LAAC) in patients at high risk of bleeding remains controversial. We present real-world clinical outcomes of LAAC.Methods and Results: Data from 74 consecutive patients who received LAAC therapy between January 2020 and June 2022 were analyzed. Patients received 1 of 3 antithrombotic therapies according to the bleeding risk category or clinical event. Regimen 1 was based on a prior study, regimen 2 comprised a lower antiplatelet drug dose without dual antiplatelet therapy, and regimen 3 was antiplatelet drug administration for as long as possible to patients with uncontrollable bleeding who were required to stop anticoagulant drugs. Overall, 73 (98.6%) procedures were successful. Of them, 16 (21.9%) patients were selected for regimen 1, 46 (63.0%) for regimen 2, and 11 (15.1%) for regimen 3. Device-related thrombosis (13% vs. 0% vs. 0%, P=0.0257) only occurred with regimen 1. There was no difference in major bleeding event rates (6% vs. 2% vs. 9%, P=0.53). CONCLUSIONS: The post-LAAC antithrombotic regimen was modified without major concerns.

Predicting therapies in Japanese hypertrophic cardiomyopathy patients with an implantable cardioverter-defibrillator using the 2014 European Society of Cardiology guidelines.

Previous studies have shown that the sudden cardiac death (SCD) prediction model proposed by the 2014 European Society of Cardiology (ESC) guideline (5-Year Risk-SCD) was validated in European patients with hypertrophic cardiomyopathy (HCM). However, there are limited data on Asian patients with HCM. We assessed the validity of the estimated 5-Year Risk-SCD in Japanese HCM patients with an implantable cardioverter-defibrillator (ICD) using the2014 ESC guidelines. We retrospectively examined data of 492 consecutive Japanese patients with an ICD. Sixty-two Japanese HCM patients with an ICD were enrolled in this study, and 50 patients (81%) were followed up for ≥ 5 years. We analyzed the characteristics and outcomes of these 50 patients. We investigated the incidence of appropriate ICD therapy as categorized by the ESC guideline and compared the 5-Year Risk-SCD with the 5-year rate of appropriate shock therapies. Based on the 2012 Japanese Circulation Society guideline and the 2011guidelines of the American Heart Association and American College of Cardiology Foundation, 10 and 40 patients met classes I and IIa of the ICD recommendation, respectively. However, only 18 (36%) patients were classified into class I or IIa of the ESC guideline. Among 50 patients followed up for ≥ 5 years after ICD implantation, the incidences of appropriate ICD therapies for classes I, IIa, IIb, and III indications based on the 2014 ESC guideline were 50%, 38%, 17%, and 0%, respectively. Risk stratification for SCD using 5-Year Risk-SCD is valid in Japanese HCM patients with an ICD, and the 2014 ESC guideline might be useful for the indication of ICD implantation in Japan.

Shortening of the atrial-His bundle interval during atrial pacing as a predictor of successful ablation for typical atrioventricular nodal re-entrant tachycardia.

Aims: Shortening of the atrial-His bundle (AH) interval during the sinus rhythm is occasionally observed after slow pathway ablation for atrioventricular nodal re-entrant tachycardia (AVNRT). In addition, high-rate atrial pacing is useful for avoiding atrioventricular block. We hypothesized that shortening of the AH interval during slow pathway ablation under high-rate atrial pacing would lead to successful ablation of typical AVNRT. Methods and results: This retrospective study included 37 patients in whom successful ablation of typical AVNRT was performed under atrial pacing. The AH interval was measured immediately before the first radiofrequency (RF) application and immediately after the last RF application, prior to the first induction. Twenty-five of 37 patients achieved procedural success at the first induction (i.e. successful group). No patients developed a prolonged AH interval or atrioventricular block. The AH interval was shortened by an average of 14.6 ± 7.7 and 1.8 ± 1.2 ms in the successful and other patient groups, respectively (P < 0.01). An AH interval decrease of > 10 ms was observed in 23 of 27 (85%) patients in the successful group, whereas all other patients had an AH interval decrease of < 5 ms. Conclusion: Shortening of the AH interval during high-rate atrial pacing is a predictor of the successful ablation for typical AVNRT.

Spore-DNA localization and extraction efficiencies of Bacillus subtilis for accurate results in quantitative real-time polymerase chain reaction.

Mechanical bead disruption is an efficient DNA extraction method from spore cells for subsequent quantification of the spore population by quantitative polymerase chain reaction（qPCR）. In this study, to validate spore DNA localization and extraction efficiencies, the fractionated DNA included the total DNA（tDNA）extracted from spore cells and intracellular（iDNA）and extracellular DNA（eDNA）extracted from fractionated spores through chemical decoating and alkaline lysis buffers, each followed by bead disruption. Furthermore, alkaline lysis buffer-treated spore cells were intensively washed three and five times after each centrifugation to determine how the amount of DNA is affected by repeated centrifugation. This process was achieved through fractionated spore pellet and suspension treatments with propidium monoazide xx（PMAxx）before mechanical bead disruption. Three fractionated and extracted DNAs were assessed with qPCR. The amount of eDNA was higher than that of iDNA, and closer to tDNA levels in the qPCR assay. These results indicted the following: 1）amount of eDNA was more than iDNA and responsible for majority of amount of tDNA through the combination method involving alkaline lysis buffer and bead disruption, 2）lysis buffer partially eliminated the eDNA fragments through multiple washing steps, but it was not largely independent of the number of times centrifugation was performed.

Interaction of left ventricular size with the outcome of cardiac resynchronization therapy in Japanese patients.

BACKGROUND: We analyzed the influence of the QRS duration (QRSd) to LV end-diastolic volume (LVEDV) ratio on cardiac resynchronization therapy (CRT) outcomes in heart failure patients classified as III/IV per the New York Heart Association (NYHA) and with small body size. HYPOTHESIS: We proposed the hypothesis that the QRSd/LV size ratio is a better index of the CRT substrate. METHODS: We enrolled 114 patients with advanced heart failure (NYHA class III/IV, and LV ejection fraction >35%) who received a CRT device, including those with left bundle branch block (LBBB) and QRSd ≥120 milliseconds (n = 60), non-LBBB and QRSd ≥150 milliseconds (n = 30) and non-LBBB and QRSd of 120-149 milliseconds (n = 24). RESULTS: Over a mean follow-up period of 65 ± 58 months, the incidence of the primary endpoint, a composite of all-cause death and hospitalization for heart failure, showed no significant intergroup difference (43.3% vs. 50.0% vs. 37.5%, respectively, p = .72). Similarly, among 104 patients with QRSd/LVEDV ≥ 0.67 (n = 54) and QRSd/LVEDV < 0.67 (n = 52), no significant differences were observed in the incidence of the primary endpoint (35.1% vs. 51.9%, p = .49). Nevertheless, patients with QRSd/LVEDV ≥ 0.67 showed better survival than those with QRSd/LVEDV < 0.67 (14.8% vs. 34.6%, p = .0024). CONCLUSION: Advanced HF patients with a higher QRSd/LVEDV ratio showed better survival in this small-body-size population. Thus, the risk is concentrated among those with a larger QRSd, and patients with a relatively smaller left ventricular size appeared to benefit from CRT.

Specific and sensitive detection of Alcaligenes species from an agricultural environment.

A quantitative real-time PCR assay to specifically detect and quantify the genus Alcaligenes in samples from the agricultural environment, such as vegetables and farming soils, was developed. The minimum detection sensitivity was 106 fg of pure culture DNA, corresponding to DNA extracted from two cells of Alcaligenes faecalis. To evaluate the detection limit of A. faecalis, serially diluted genomic DNA from this organism was mixed with DNA extracted from soil and vegetables and then a standard curve was constructed. It was found that Alcaligenes species are present in the plant phytosphere at levels 10(2)-10(4) times lower than those in soil. The approach presented here will be useful for tracking or quantifying species of the genus Alcaligenes in the agricultural environment.

An improved DNA extraction method for detecting Bacillus subtilis spores in spiked foods and beverages.

Bacillus and Paenibacillus spp. are essential aerobic spoilage bacteria in various food industry sectors. Spoilage from microorganisms occurs at many points throughout food production systems. Due to their complex wall structures, spores can resist heat, radiation, chemical agents, and enzymatic treatments. An alkaline lysis and mechanical disruption combination method was developed and evaluated to counter this. This combination method effectively improved DNA extraction from B. subtilis spore cells spiked into food (solid) and beverages (liquid milk and coffee) at concentrations down to 102 CFU/mL or g when spiked into food matrices and drinks. Released DNA recoveries were 27 % and 25 % for potato salad and 38 % and 36 % for whole corn spiked at 106 and 103 CFU/mL concentrations. Conversely, there was a low recovery for wheat flour (10 % and 8.8 %) and milk powders (12 % and 25 %) at 106 and 103 CFU/mL spiked concentrations. The combination method provides rapid, specific, reliable, and accurate signature sequences identification for the detection and presence confirmation of psychrophilic and psychrotolerant spoilage spore cells, improving food spoilage assessments and food control applications.

Right ventricular systolic function as a predictor of appropriate ICD therapy.

BACKGROUND: Recent studies have shown that right ventricular dysfunction is associated with a significantly increased risk of sudden cardiac death. The purpose of this study was to evaluate the association of the right ventricular fractional area change (RVFAC) and appropriate implantable cardioverter-defibrillator (ICD) therapy to determine the cutoff value of the RVFAC. METHODS: Consecutive patients who underwent initial ICD implantations except those with hypertrophic cardiomyopathy, Brugada syndrome, and long QT syndrome were retrospectively enrolled. The primary endpoint was defined as any appropriate ICD therapy. The right ventricular dimensions and function on transthoracic echocardiography were measured for analysis. RESULTS: In total, 172 patients (60.3 ± 13.6 years, 131 males) were enrolled. Ninety patients received an ICD as a secondary prophylaxis. The mean LV ejection fraction and RVFAC were 38.3 ± 14.3% and 35.8 ± 8.8%, respectively. Regarding appropriate ICD therapy events, the best cutoff value of the RVFAC was 34.8%, while 74 patients had an RVFAC < 34.8%. Regarding the primary endpoint, the hazard ratio of a low RVFAC was 2.73 (95% CI 1.46-5.12, P < 0.01). In the multivariate analysis, a low RVFAC was an independent predictor of appropriate ICD therapy (HR: 3.40, 95% CI 1.74-6.64, P < 0.01). The secondary prophylactic cohort with a low RVFAC had the highest incidence of appropriate ICD therapy. Among the patients with RV dysfunction, the RVFAC normalized in 39% of patients during follow-up. This recovered RVFAC group had a significantly lower incidence of appropriate ICD therapy than the unrecovered RVFAC group (P = 0.043). CONCLUSION: A low RVFAC might be associated with increased appropriate ICD therapy.

Extracellular neutral lipids produced by the marine bacteria Marinobacter sp.

We analyzed the production of neutral lipids by the marine hydrocarbonoclastic bacteria Marinobacter sp. strain PAD-2 using hexadecane or succinate as the sole carbon source. Results showed that strain PAD-2 was able to grow and reduce the surface tension to 33±1.5 mN m(-1) and 58±1.5 mN m(-1) when n-hexadecane or succinate was used as the sole carbon source, respectively. The lipophilic compounds produced by Marinobacter sp. strain PAD-2 were extracted, and then crude lipophilic compounds, expected to be wax ester-like lipids, were analyzed by thin layer chromatography (TLC) . Furthermore, the lipophilic compound demonstrating surface activity was purified and subjected to gas chromatography/mass spectrometry (GC/MS) analysis. Although these did not give definite structural information due to the weak molecular ion peak (M(+)) , one component Ma-1 showed almost the same mass spectrum as that of component Fa-2, which represented a biosurfactant derived from Dietzia maris reported previously. Cell hydrophobicity was measured by a test of bacterial adhesion to hydrocarbons. A higher hydrophobic cell surface was observed in strain PAD-2. Extracellular wax ester-like compounds seem to be one type of the surface active compounds when bacteria grow on hexadecane or succinate as the sole carbon source.

Bacterial diversity associated with the rotifer Brachionus plicatilis sp. complex determined by culture-dependent and -independent methods.

The bacterial communities associated with rotifers (Brachionus plicatilis sp. complex) and their culture water were determined using culture-dependent and -independent methods (16S rRNA gene clone library). The bacterial communities determined by the culture-independent method were more diverse than those determined by the culture-dependent method. Although the culture-dependent method indicated the bacterial community of rotifers was relatively similar to that of the culture water, 16S rRNA gene clone library analyses revealed a great difference between the two microbiotas. Our results suggest that most bacteria associated with rotifers are not easily cultured using conventional methods, and that the microbiota of rotifers do not correspond with that of the culture water completely.

Wax ester-like compounds as biosurfactants produced by Dietzia maris from n-alkane as a sole carbon source.

The hydrocarbon-degrading bacterium Dietzia maris WR-3 was isolated from a consortium comprising ammonia-oxidizing and denitrifying bacteria derived from marine sediments. Here, we examined biosurfactant production by strain WR-3 when cultured using several different carbon (D-glucose, n -decane, n -hexadecane, motor oil, olive oil, and rapeseed oil) and nitrogen (NH(4) )(2) SO(4) , NaNO(3) , yeast extract, and polypeptone) sources as growth substrates. Strain WR-3 was able to grow and reduce the surface tension of culture broth to 31±1.0 mN m(-1) when cultured using n -hexadecane and nitrate ions. The surface-active compounds produced by strain WR-3 were extracted and analyzed by thin layer chromatography. Moreover, the main components in the extract were further purified and subjected to gas chromatography/mass spectrometry (GC/MS). From the analysis, the surface-active compounds were tentatively identified as wax ester-like compounds, which were synthesized from the degradation process of n -alkane. The production of surface-active compounds by strain WR-3 promoted attachment of cells to hydrocarbon droplets via increased cell hydrophobicity, thus allowing enhanced degradation of water immiscible substrates. As Dietzia spp. can grow and produce wax esters from the degradation process of hydrocarbons, these marine bacteria are potentially useful for the bioremediation of hydrocarbon-contaminated environments.

Peak deflection index as a predictor of a free-wall implantation of contemporary leadless pacemakers.

BACKGROUND: Leadless pacemakers are an effective treatment for bradycardia. However, some cases exhibit pericardial effusions, presumably associated with device implantations on the right ventricular free-wall. The present study was carried out to find the ECG features during ventricular pacing with a Micra, which enabled distinguishing free-wall implantations from septal implantations without using imaging modalities. METHODS: Thirty-one consecutive patients who received Micra implantations in our facility were enrolled. The location of the device in the right ventricle was evaluated using echocardiography or computed tomography in order to determine whether the device was implanted on the septum (Sep group), apex (Apex group), or free-wall (FW group). The differences in the 12-lead ECG during ventricular pacing by the Micra were analyzed between the Sep and FW groups. RESULTS: The body of the Micra was clearly identifiable in 22 patients. The location of the device was classified into Sep in 12 patients, Apex in 4, and FW in 6. The mean age was highest in the FW and lowest in the Sep group (82.7 ± 6.6 vs. 72.8 ± 8.7 years, p = 0.027). The peak deflection index (PDI) was significantly larger in the FW group than Sep/Apex group in lead V1 (Sep: 0.505 ± 0.010, Apex: 0.402 ± 0.052, FW: 0.617 ± 0.043, p = 0.004) and lead V2 (Sep: 0.450 ± 0.066, Apex: 0.409 ± 0.037, FW: 0.521 ± 0.030, p = 0.011), whereas there was no difference in the QRS duration, transitional zone, and QRS notching. CONCLUSION: The PDI in V1 could be useful for predicting implantations of Micra devices on the free-wall and may potentially stratify the risk of postprocedural pericardial effusions.

Pathophysiological background and prognosis of common atrial flutter in non-elderly patients: Comparison to Atrial Fibrillation.

BACKGROUND: It is unclear whether there is any difference in the background and prognosis between non-elderly patients who undergo catheter ablation of atrial fibrillation (AF) and common atrial flutter (CAFL). PURPOSE: To investigate the difference between the patient background of both CAFL and AF in the non-elderly. METHODS: In 526 consecutive patients who underwent catheter ablation of clinical paroxysmal/persistent CAFL or AF in our hospital, we enrolled only patients under 60 years old. Cases harboring both AFL and AF were excluded. We analyzed the patient characteristics, echocardiographic findings, electrocardiographic (ECG) abnormalities during sinus rhythm, and clinical course after ablation. RESULTS: In total, 196 patients (Cohort 1: 142 males, 156 AF cases) were analyzed. AFL patients were younger than AF patients (47.4 ± 10.6 vs. 50.2 ± 6.4years, p = 0.031) and organic heart disease (OHD) was significantly more common in AFL patients than AF patients (42.5% vs. 11.5%, p<0.001). In 161 patients excluding OHD (Cohort 2), ECG abnormalities were more frequent in AFL than in AF patients (78.3% vs. 39.1%, p = 0.001). There were no significant differences in all-cause death, onset of heart failure, and cerebral strokes. On the other hand, the number of cases that required a pacemaker was significantly higher in the CAFL group than AF group (0.0% vs. 26.1%, p-value <0.001). These results suggested that CAFL may reflect occurrence of any atrial myocardial damage, even if it does not lead to heart failure. CONCLUSIONS: Our present study suggested that CAFL may be associated with a broader atrial myocardial disorder in non-elderly patients.

Effect of salinity on denitrification under limited single carbon source by Marinobacter sp. isolated from marine sediment.

Marinobacter comprises Gram-negative, aerobic, motile, and rod-shaped bacteria within the gamma-subclass of the Proteobacteria and is known to be halophilic or halotolerant, heterotrophic neutrophile. Two strains classified as belonging to Marinobacter, named PAD-2 and SeT-1, were isolated from marine sediment. The most closely related species of PAD-2 and SeT-1 are M. alkaliphilus and M. guinea, respectively. The strain PAD-2 exhibited remarkably higher denitrification at concentrations of 0.5 to 1 M NaCl (3-6% w/w) than at other salinities (2 and 3 M NaCl, 12-18% w/w), and optimal denitrification was observed in media with 0.5 M NaCl. The effect of pH on denitrification by strain PAD-2 was also examined, and the optimum denitrification occurred at neutral pH rather than under alkaline conditions. Overall, strain PAD-2 appears to be a novel halotolerant species belonging to the genus Marinobacter that shares many characteristics, such as substrate utilization profile and optimum NaCl concentration for growth with M. alkaliphilus.

Development of a multiplex real-time PCR assay for the identification and quantification of group-specific Bacillus spp. and the genus Paenibacillus.

Spoilage microorganisms can occur at many points throughout food production systems. Bacillus spp. and Paenibacillus spp. are important aerobic spoilage bacteria in various sectors of the food industry. In this study, we developed a rapid detection and quantification technique for Bacillus group-specific and the genus Paenibacillus by using multiplex quantitative PCR (mqPCR). The 1st was the Bacillus cereus group containing B. cereus and B. weihenstephanensis; the 2nd was the B. subtilis group containing B. subtilis, B. licheniformis, B. safensis, and B. pumilus; the 3rd was the B. simplex group containing B. megaterium and B. simplex; and the 4th was the genus Paenibacillus. Depending on the assays, the detection limit was 10 copy numbers. In addition, mqPCR assays were validated by spiking potato salad and milk samples with four strains; B. weihenstephanensis, B. licheniformis, B. megaterium, and P. lautus. The detection dynamic range for potato salad was 105 CFU/mL-101 CFU/mL with B. weihenstephanensis and B. licheniformis, and 105 CFU/mL-102 CFU/mL with B. megaterium and P. lautus, while, for milk, all strains were 105 CFU/mL-102 CFU/mL. We also stored these food matrices spiked with four bacterial suspensions (approximately 103 CFU/mL) at various temperatures. Results showed that B. weihenstephanensis and B. licheniformis were able to grow in potato salad, whereas, the populations of B. weihenstephanensis, B. licheniformis, and P. lautus increased in milk. Consequently, the mqPCR assays developed here in facilitated the differentiation, quantification, and confirmation of the presence of the psychrophilic and psychrotolerant Bacillus group and Paenibacillus spp.

Comparison of the performance of implantable cardioverter-defibrillator leads among manufacturers.

BACKGROUND: Leads are often considered the weakest link in implantable cardioverter-defibrillator (ICD) systems, and lead dysfunction is a major concern for ICD recipients. The aim of this study was to compare the lead performance from three different manufacturers. METHODS: We retrospectively reviewed consecutive patients who underwent ICD system implantation at Chiba University Hospital, Japan, between March 2008 and September 2017. The following leads were implanted in our center: Durata (St. Jude Medical, St. Paul, MN, USA, now Abbott) (n = 105), Linox and LinoxSmart (Biotronik, Berlin, Germany) (n = 66), and Sprint Quattro (Medtronic, Minneapolis, MN, USA) (n = 126). RESULTS: A total of 297 ICD leads were analyzed. Failure rates for Durata, Linox/LinoxSmart, and Sprint Quattro were 0.20%/patient year, 0.95%/patient year, and 1.84%/patient year, respectively, during a mean follow-up of 4.8, 6.4, and 3.0 years, respectively. The cumulative ICD lead survival probability was 98.9%, 100%, and 87.5%, after 5 years, respectively. The survival probability over the entire follow-up time as measured by the log-rank test was lower for Sprint Quattro leads than for either Durata (p = 0.011) or Linox/LinoxSmart (p = 0.028). The difference between Durata and Linox/LinoxSmart was not significant (p = 0.393). CONCLUSIONS: In this single-center retrospective study, the performance of Sprint Quattro was lower than the performance of Linox/LinoxSmart and Durata leads. Large-scale, multi-center studies or manufacturer-independent registries may be necessary to confirm or reject self-reported survival probabilities from manufacturers' product performance reports.

Estimation of the accessory pathway location of the manifest Wolf-Parkinson-White syndrome using synthesized right-sided chest leads.

PURPOSE: The classification using QRS morphology of V1 lead is a useful simple predictor of accessory pathway location (type A, R or Rs pattern; type B, rS pattern; type C, QS or Qr pattern), but often leads to misdiagnosis of accessory pathway location, especially in types B and C. The synthesized 18-lead electrocardiography (ECG) derived from standard 12-lead ECG can provide virtual waveforms of right-sided chest leads. This study aimed to evaluate the usefulness of the right-sided chest lead ECG for prediction of accessory pathway location. METHODS: This retrospective study included 44 patients in whom successful ablation of manifest Wolff-Parkinson-White (WPW) syndrome was performed. Synthesized ECG waveforms were automatically generated, and ECG data obtained before the procedure. RESULTS: There were 26, 4, and 14 patients with left, right, and septal accessory pathways, respectively. All left accessory pathway cases have type A in V1 and syn-V4R leads. Of the 4 right accessory pathway cases, 2 have type B in V1 and syn-V4R leads. Other 2 of 4 cases have type C. In V1 lead, 5 of 14 septal accessory pathway cases have type C, 7 of 14 cases have type B, and 2 of 14cases have type A. In syn-V4R lead, all 14 septal accessory pathway cases have type C. The QRS morphology of V1 and syn-V4 leads could predict the site of accessory pathway with overall accuracy of 79% and 95%, respectively. CONCLUSIONS: QRS morphology of syn-V4R lead may be useful for predicting accessory pathway location of manifest WPW syndrome.