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Background: QRS morphology can change during ventricular arrhythmias (VAs) with the appearance of bundle branch block (BBB). Methods: We retrospectively investigated 195 consecutive patients who underwent an initial ablation of VA. The study inclusion criteria were VAs that were successfully ablated in the outflow tract (OT) and in whom right bundle branch block (RBBB) was induced by catheter manipulation close to the His bundle area during sinus rhythm, before any radiofrequency application. We analyzed the QRS morphology of the VAs with and without RBBB during sinus beats. Results: Twenty‐four patients (age 59 ± 17 years, female 14) developed RBBB at some point during their procedure. The successful ablation sites of the VAs were the right ventricular outflow tract (RVOT) in 12 patients, pulmonary artery in one, left coronary cusp in five, right coronary cusp in three, right‐left cusp junction in two, and great cardiac vein in two. QRS‐morphology change was observed in five (20%) cases. The successful ablation sites in that group were the left coronary cusp in three cases, right coronary cusp in one, and RVOT septum in one. The QRS duration of the VAs increased during RBBB. Conclusions: There are some cases of OT‐VAs in which the QRS waveform changes with the appearance of catheter induced RBBB. We need to be aware that when QRS morphology changes during an OT‐VA ablation, it does not necessarily mean that the origin or exit of the VA has changed. [ABSTRACT FROM AUTHOR]

Introduction: It would be helpful in determining ablation strategy if the occurrence of perimitral atrial tachycardia (PMAT) could be predicted in advance. We investigated whether estimated perimitral conduction time (E‐PMCT), namely, twice the time between coronary sinus (CS) pacing and the ensuing wave‐front collision at the opposite side of the mitral annulus, correlated with the cycle length of PMAT and could predict future PMAT. Methods and Results: We retrospectively (retrospective cohort) and prospectively (validation cohort) investigated atrial fibrillation patients who had received pulmonary vein isolation (PVI) and in whom left atrial maps had been created during CS pacing. We calculated their E‐PMCT. PMAT was observed either by provocation or during follow‐up in 25, AT other than PMAT was observed in 24 (non‐PMAT AT group), and 53 patients never displayed any AT (no‐AT group) in the retrospective cohort. In the PMAT group of the retrospective cohort, a strong positive correlation was observed between the PMAT CL and E‐PMCT (r =.85, p < 0.001). PMAT was never induced nor observed in patients with E‐PMCT less than 176 ms, and the best cut‐off value for PMAT was 180 ms by receiver‐operating characteristic curve analysis. In the validation cohort of 76 patients, the cut‐off value of the E‐PMAT less than 180 ms predicted noninducibility of PMAT, with a sensitivity of 78.6%, specificity of 100%, positive predictive value of 100%, and negative predictive value of 25.0%. Conclusion: Short E‐PMCT may predict noninducibility of PMAT and guide a less invasive ablation strategy. [ABSTRACT FROM AUTHOR]

The article presents a case study of a 44-year-old female patient who underwent catheter ablation therapy for a slightly irregular supraventricular tachycardia (SVT). It also discusses the mechanisms of ventriculoatrial (VA) block during SVT, the differential diagnosis involving various types of tachycardias, and the role of upper common pathway (UCP) in AVNRT.

Background: Although atrial flutter (AFL) is a common arrhythmia that is based on a macro‐reentrant tachycardia around the tricuspid annulus, the factors giving rise to typical AFL (t‐AFL) versus reverse typical AFL (rt‐AFL) are unknown. To investigate the difference between t‐AFL and rt‐AFL circuits using ultrahigh resolution mapping of the right atrium. Methods: We investigated 30 isthmus‐dependent AFL patients (mean age 71, 28 male) who underwent first‐time cavo‐tricuspid isthmus (CTI) ablation guided by Boston Scientific's Rhythmia mapping system and divided them into two groups: t‐AFL (22 patients) and rt‐AFL (8 patients). We compared the anatomy and electrophysiology of their reentrant circuits. Results: Baseline patient characteristics, use of antiarrhythmic drugs, prevalence of atrial fibrillation, AFL cycle length (227.1 ± 21.4 vs. 245.5 ± 36.0 ms, p =.10), and CTI length (31.9 ± 8.3 vs. 31.1 ± 5.2 mm, p =.80) did not differ between the two groups. Functional block was observed at the crista terminalis in 16 patients and at the sinus venosus in 11. No functional block was observed in three patients, all of whom belonged to the rt‐AFL group. That is, functional block was observed in 100% of the t‐AFL group as opposed to 5/8 (62.5%) of the rt‐AFL (p <.05). Slow conduction zones were frequently observed at the intra‐atrial septum in the t‐AFL group and at the CTI in the rt‐AFL group. Conclusion: Mapping with ultrahigh‐resolution mapping showed differences between t‐AFL and rt‐AFL in conduction properties in the right atrium and around the tricuspid valve, which suggested directional mechanisms. [ABSTRACT FROM AUTHOR]

Introduction: Mitral valve surgery employing a superior transseptal approach (STA) is associated with arrhythmogenicity and intra‐atrial conduction delay, despite being optimal for visualization of the surgical field. It is sometimes difficult to treat atrial tachycardias (AT) that arise after STA. To investigate AT circuits that arise after STA in detail in order to identify the optimal ablation line, using ultra‐high‐resolution mapping (UHRM). Methods: We retrospectively analyzed 12 AT from 10 patients (median age 70 years, nine males) who had undergone STA surgery. The tachycardias were mapped using the Rhythmia mapping system (Boston Scientific, Natick, Massachusetts). Results: The 12 STA‐related AT (STA‐AT) circuits were classifiable as follows according to location of the optimal ablation line: (1) peri‐septal incision STA‐AT (n = 3), (2) cavotricuspid isthmus (CTI) dependent STA‐AT (n = 7), and (3) biatrial tachycardia (n = 2). Radiofrequency (RF) application terminated 11 of the 12 STA‐AT. We found that difference in STA‐AT circuit type was due to characteristics of the septal incision line made for STA. UHRM was important in identifying optimal ablation sites that did not create additional conduction disturbances in the right atrium (RA). Conclusions: ATs after STA involve complex arrhythmia circuits due to multiple and long incision lines in the RA. Accurate understanding of the arrhythmia circuit and sinus conduction in the RA after STA is recommended for treating post‐surgical tachycardia in a minimally invasive manner. [ABSTRACT FROM AUTHOR]

Objective: The aim of this study was to evaluate the remineralization of residual demineralized dentin underneath restorations by fluoride-releasing liners in vitro. Method and materials: Two glass-ionomer cement liners, Lining Cement (GC) and RK-141A (GC), and two light-cured resin liners with and without 5 wt% NaF were used in this study The resin liners were made by mixing TEGDMA and bis-GMA. Class 5 cavities were prepared on extracted human premolars. Demineralized dentin was promoted by using a bacterial caries induction system at the cavity floor. Cavities were restored with a resin composite following application of each liner. Specimens were then stored for 4 weeks at 37°C and 100% humidity After storage, the specimens were cut through the restorations, and axial sections of about 80-μm thickness were prepared. Contact microradiographs were taken, and the radiopacity of the demineralized dentin layer underneath the liner was analyzed. Results: The ratios of radiopacity of demineralized dentin under the fluoride-releasing liners were significantly higher than those under the resin liner without fluoride release. Although the amounts of fluoride release from the glass-ionomer cement liners were lower than that from the resin liner with fluoride release, there were no significant differences in the ratios of radiopacity in demineralized dentin layers among the 3 liners with fluoride release. Conclusion: Although the fluoride released from liners can enhance remineralization of demineralized dentin, the amount of fluoride release does not affect the ratio of radiopacity in the remineralized dentin. [ABSTRACT FROM AUTHOR]

Focal AT and Recurrence After AF Ablation Introduction Catheter ablation can terminate persistent atrial fibrillation (AF). However, atrial tachycardia (AT) often arises after termination of AF. Methods and Results Of 215 patients who underwent index stepwise ablation for persistent AF, 141 (66%) patients (64 ± 9 years) in whom AF terminated during the ablation procedure were studied. If AF converted into AT, ablation for AT was subsequently performed. ATs were categorized as focal or macroreentrant AT. We assessed whether type of AT occurring after conversion of AF during the ablation procedure was associated with freedom from atrial tachyarrhythmia (AF or AT) during follow-up. Sinus rhythm was directly restored from AF in 37 patients, while 34, 37, and 33 patients had focal AT alone, a mix of focal and macroreentrant AT, and macroreentrant AT alone after termination of AF, respectively. Arrhythmia-free survival rates at 1 year after the index procedure were 30%, 34%, 61%, and 59% in the patients with focal AT alone, a mix of focal AT and macroreentrant AT, macroreentrant AT alone, and direct restoration of sinus rhythm, respectively (P = 0.004). Type of AT occurring during the index procedure was associated with type of recurrent AT (P = 0.03), but the origin of focal AT occurring during the index ablation differed from that of the recurrent AT in 85% of patients. Conclusion In patients who had AF termination by ablation, occurrence of focal AT during the ablation procedure was associated with worse clinical outcome than occurrence of macroreentrant AT, likely due to ATs arising from other foci during follow-up. [ABSTRACT FROM AUTHOR]

Purpose: To evaluate the bonding of an experimental antibacterial fluoride-releasing adhesive system (ABF) to normal and carious dentin in human teeth with Class V root caries. Methods: Mesiodistal sectioning removed the buccal enamel, superficial dentin and much of the carious dentin in 21 extracted human bicuspids with root surface caries. The surfaces of normal coronal and root dentin, and caries-affected and caries-infected dentin were ground with wet 600-grit SiC paper to create a standardized smear layer Tooth surfaces were treated with the ABF according to manufacturer's instructions, and then covered with excess resin composite. After immersion in 37°C water for 24 hours, the restored teeth were horizontally sectioned into serial slabs that were trimmed into hourglass shapes to isolate the bonded area to the test substrates, and then their bond strengths were measured by the micro tensile bond test, and the interfaces examined by SEM and TEM. The bond strengths were statistically compared with ANOVA and Fisher's PLSD (P< 0.05). Results: The bond strengths of ABF to caries-affected and caries-infected dentin were significantly lower than those to normal coronal and root dentin. SEM micrographs revealed that the hybrid layers in caries-affected and caries-infected dentin were more porous compared to the hybrid layer in normal coronal and root dentin. TEM micrographs showed that bacteria that had invaded the dentin were embedded in this adhesive monomer in caries-infected dentin. [ABSTRACT FROM AUTHOR]

Purpose: To investigate the microtensile bond strength (µTBS) of a self-etching pruning adhesive system to normal, caries-affected and caries-infected dentin, and to observe the ultrastructure of the resin-dentin interface by transmission electron microscopy (TEM). Materials gad Methods: Twelve extracted human molar teeth with deep occlusal caries were stained with caries detector solution and ground flat occlusally. The red-stained soft dentin was classified as caries-infected. The surrounding discolored dentin was classified as caries-affected dentin. The surrounding normal dentin served as a control. The entire flat surface was bonded with Clearfil Liner Bond 2V (CV) and covered with resin composite to form a composite crown 5 mm high. One day later the specimens were serially sectioned vertically into multiple slabs 0.8 mm thick. Under microscopic observation, the specimens were divided into normal or caries-infected or caries-affected dentin. These regions were isolated by cutting away the remaining dentin to form hour-glass shapes with the smallest surface area at the test site. After measuring the areas, the specimens were fixed to a microtensile tester and pulled under tension to failure. Additional slabs that were not used for bond strength tests were processed for TEM. Bond strength data were analyzed by Kruskal-Wallis one-way ANOVA and Student-Newman-Keuls multiple comparisons. Results: The µTBS of CV to normal, caries-affected and caries-infected dentin were 45 ± 10 MPa, 30 ± 10 MPa. 10 ± 5 MPa, respectively. TEM images showed that CV formed thin hybrid layers that were less than 1 urn thick in normal dentin, but that were between 6-8 µm thick in canes-affected dentin. Bacteria were only sparsely observed in the dentin tubules of bonded caries-affected dentin. However, in caries-infected dentin, an unusual interface was seen in which carious bacteria within disorganized non-banded collagen Fibrils could be seen embedded by the adhesive. The hybrid layer in caries-infected dentin was found to be 30-60 µm thick. [ABSTRACT FROM AUTHOR]

Background: The concept of ablation index (AI) was introduced to evaluate radiofrequency (RF) ablation lesions. It is calculated from power, contact force (CF), and RF duration. However, other factors may also affect the quality of ablation lesions. To examine the difference in RF lesions made during sinus rhythm (SR) and atrial fibrillation (AF)., Methods: Sixty patients underwent index pulmonary vein isolation during SR ( n  = 30, SR group) or AF ( n  = 30, AF group). All ablations were performed with a power of 50 W, a targeted CF of 5-15 g, and AI of 400-450 using Thermocool Smarttouch SF. The CF, AI, RF duration, temperature rise (Δtemp), impedance drop (Δimp), and the CF stability of each ablation point quantified as the standard deviation of the CF (CF-SD) were compared between the two groups., Results: A total of 3579 ablation points were analyzed, which included 1618 and 1961 points in the SR and the AF groups, respectively. Power, average CF, RF duration per point, and the resultant AI (389 ± 59 vs. 388 ± 57) were similar for the two rhythms. However, differences were seen in the CF-SD (3.5 ± 2.2 vs. 3.8 ± 2.1 g, p  < .01), Δtemp (3.8 ± 1.3 vs. 4.0 ± 1.3°C, p  < .005), and Δimp (10.3 ± 5.8 vs. 9.4 ± 5.4 Ω, p  < .005)., Conclusions: Despite similar AI, various RF parameters differed according to the underlying atrial rhythm. Ablation delivered during SR demonstrated less CF variability and temperature increase and greater impedance drop than during AF., Competing Interests: The authors declare no conflicts of interest., (© 2024 The Authors. Journal of Arrhythmia published by John Wiley & Sons Australia, Ltd on behalf of Japanese Heart Rhythm Society.)

Hybridized dentin permits dental treatments that were previously impossible with conventional techniques, opening new frontiers in modern adhesive dentistry. We have investigated the adhesive property of current bonding systems to caries-infected dentin by a microtensile bond strength test (µTBS) and transmission electron microscopy (TEM), and suggested that bonding resin could infiltrate into caries-infected dentin partially to embed carious bacteria within hybrid layers. We have named this concept of caries control as modified sealed restoration (MSR). On the other hand, Kuraray Medical Inc. (Tokyo, Japan) has developed an antibacterial adhesive system (ABF, now marketed in USA as Protect Bond). So as to evaluate the effectiveness of ABF on root caries control, we have examine the microtensile bond strengths (µTBS) of ABF to normal versus carious root dentin and the interfacial morphology by a scanning electron microscopy (SEM). ABF could form the hybrid-like structures by infiltrating into the surfaces of the root carious dentin, and the mean value of µTBS of ABF to root carious dentin was 23.0 MPa. These results suggested that MSR combined with ABF might be an advantageous minimal invasive therapy for root caries.