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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]

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]

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]

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]