Measurement and Analysis of Atomic Hydrogen and Diatomic Molecular AlO,C2, CN,and TiO Spectra Following Laser-induced Optical Breakdown

In this work, we present time-resolved measurements of atomic and diatomic spectra following laser-induced optical breakdown. A typical LIBS arrangement is used. Here we operate a Nd:YAG laser at a frequency of 10 Hz at the fundamental wavelength of 1,064 nm. The 14 nsec pulses with anenergy of 190 mJ/pulse are focused to a 50 µm spot size to generate a plasma from optical breakdown or laser ablation in air. The microplasma is imaged onto the entrance slit of a 0.6 m spectrometer, and spectra are recorded using an 1,800 grooves/mm grating an intensified linear diode array and optical multichannel analyzer (OMA) or an ICCD. Of interest are Stark-broadened atomic lines of the hydrogen Balmer series to infer electron density. We also elaborate on temperature measurements from diatomic emission spectra of aluminum monoxide (AlO), carbon (C₂), cyanogen (CN), and titanium monoxide (TiO).The experimental procedures include wavelength and sensitivity calibrations. Analysis of the recorded molecular spectra is accomplished by the fitting of data with tabulated line strengths. Furthermore, Monte-Carlo type simulations are performed to estimate the error margins. Time-resolved measurements are essential for the transient plasma commonly encountered in LIBS.     

Epicardial Ablation of Focal Atrial Tachycardia Arising From Left Atrial Appendage in Children

Focal left atrial tachycardia (FLAT) although a common cause of supraventricular tachycardia(SVT) among children, the one''s arising from left atrial appendage (LAA) present a unique challenge for successful ablation because of anatomical location. We present two children with FLAT arising from the epicardial LAA, successfully mapped and ablated through percutaneuous epicardial approach.     

Evaluation of the Serratia Marcescens Nuclease (NucA) as a Transgenic Cell Ablation System in Porcine

The efficiency of the Serratia marcescens nuclease encoded by the NucA gene, with or without a nuclear localization signal (NLS), and the commonly used diphtheria toxin A (DTA) were compared for their ability to ablate cells in culture. Constructs containing the test genes driven by the β-actin promoter coupled with enhancer elements from the cytomegalovirus promoter and rabbit β-globin gene (pCAG) and the blasticidin resistance gene driven by the phosphoglycerate kinase (PGK) promoter were generated and electroporated into porcine fetal fibroblasts. Three independent replicates were completed. Following blasticidin selection, the number of surviving colonies was counted to assess the efficiency of the toxic gene. Both NucA and DTA proved to be effective in killing porcine fibroblasts compared to controls. However, the efficiency of cell ablation was significantly higher with DTA than with NucA or NucANLS (p < 0.05). Gene expression analysis of surviving colonies indicated that survival is related to low or absent expression of the toxic genes. These results indicate that the NucA gene, while capable of mammalian cell ablation, is less efficient than DTA.     

Relationship between ablation index and myocardial biomarkers after radiofrequency catheter ablation for atrial fibrillation

BackgroundFurther in-vivo evidence is needed to support the usefulness of ablation index (AI) in guiding atrial fibrillation (AF) ablation. We aimed at evaluating the relationship between AI and other lesion indicators and the release of myocardial-specific biomarkers following radiofrequency AF ablation.MethodsForty-six patients underwent a first-time radiofrequency AF ablation and were prospectively enrolled in this study. Pulmonary vein isolation was performed by six experienced electrophysiologists with a point-by-point approach, guided by strict Visitag criteria and consistent AI target values. Myocardial-specific biomarkers troponin T and creatine kinase myocardial band were measured after 6 (TnT6 and CKMB6) and 20 h (TnT20 and CKMB20) following sheath removal. Ablation duration, impedance drop (ID), force-time integral (FTI) and AI were registered automatically and analyzed offline.ResultsTnT release was 985 ± 495 ng/L and 1038 ± 461 ng/L (p = ns) while CKMB release was 7.3 ± 2.7 μg/L and 6.5 ± 2.1 μg/L (p < 0.001) at 6 and 20 h respectively. Ablation duration, ID, FTI and AI were all significantly correlated with the release of myocardial-specific biomarkers both at 6 and 20 h. Ablation index showed the highest degree of correlation with TnT6, TnT20, CKMB6 and CKMB20 (Pearson's R 0.69, 0.69, 0.61, 0.64 respectively, p < 0.001). Multiple regression analysis demonstrated that AI had the strongest association with TnT6, TnT20, CKMB6 and CKMB20 (β 0.43, β 0.71, β 0.44 and β 0.43 respectively).ConclusionAblation index appears as the strongest lesion indicator as measured by the release of myocardial-specific biomarkers following radiofrequency catheter ablation for AF.     

Extensive Preferential Pathway Ablation for the Elimination of Premature Ventricular Contractions Arising from the Right Ventricular Outflow Tract

A 76 y/o women presented with 2 different types of premature ventricular contractions (VPCs 1 and 2) arising from the right ventricular outflow tract (RVOT). Catheter ablation (CA) eliminated PVC1 at the earliest activation site (EAS), but thereafter another PVC morphology (PVC3) appeared. Small potentials preceding the local potential were broadly exhibited from the RVOT’s supero-anterior region to the EAS during PVC3. Point CA targeting such prepotentials failed. Transverse-linear CA with a line connecting sites with such pre-potentials eliminated both PVCs 3 and 2. In cases with broadly spreading preferential pathways, extensive CA might be needed to eliminate the PVCs.     

Catheter entrapment in Chiari network: Extraction with radiofrequency

We report a challenging case of a duodecapolar mapping catheter entrapment in Chiari network and its release by radiofrequency energy application with an ablation catheter.     

Feasibility of fast ventricular tachycardia mapping using the Rhythmia ™ system in a patient with an Impella ™

Use of 3D navigation systems may be sometimes impossible in patients with left ventricular assist devices because of major electromagnetical interferences with some 3D systems based on magnetic localization. Mapping with the Rhythmia ™ system in patients implanted with an Impella ™ is described to be non feasible. We relate how to overcome this technical issues in this case.     

Anatomic guided ablation of the atrial right ganglionated plexi is enough for cardiac autonomic modulation in patients with significant bradyarrhythmias

IntroductionCardiac autonomic system modulation by endocardial ablation targeting atrial ganglionated plexi (GP) is an alternative strategy in selected patients with severe functional bradyarrhythmias, although no consensus exists on the best ablation strategy. The aim of this study was to evaluate if a simplified approach by a purely anatomical guided ablation of just the atrial right GP is enough for the treatment of these patients.MethodsWe prospectively enrolled patients with significant functional bradyarrhythmias and performed endocardial ablation purely guided by 3D electroanatomic mapping directed at the atrial right GP and accessed parameters of parasympathetic modulation and recurrence of bradyarrhythmias.ResultsThirteen patients enrolled (76.9% male, median age 51, 42–63 years). After ablation, a median RR interval shortening of 28.3 (25.6–40.3)% occurred (1111, 937.5–1395.4 ms to 722.9, 652.2–882.4 ms, p = 0.0002). The AH interval also shortened (19, 10.5–35.7%) significantly after the procedure (115, 105–122 ms to 85, 71–105 ms, p = 0.0023) as well as Wenckebach cycle length (11.1, 5.9–17.8% shortening) from 450, 440–510 ms to 430, 400–460 ms, p = 0.0127. On 24-h Holter monitoring there was significant increase in heart rates (HR) of patients after ablation (minimal HR increased from 34 (26–43)bpm to 49 (43–56)bpm, p = 0,0102 and mean HR from 65 (47–72)bpm to 78 (67–87)bpm, p = 0.0004). No patients had recurrence of symptoms or significant bradyarrhythmias during a median follow-up of 8.4 months.ConclusionsA purely anatomic guided procedure directed only at the atrial right ganglionated plexi seems to be enough as a therapeutic approach for cardioneuroablation in selected patients with significant functional bradyarrhythmias.     

Ablation index-guided 50W radiofrequency ablation for left atrial posterior wall isolation in atrial fibrillation

BackgroundAblation index (AI)-guided ablation for posterior wall isolation (PWI) using high-power, short-duration remains untested. We sought to evaluate the acute outcomes of AI-guided 50 W ablation vs. conventional ablation, and investigate the differences in relationship between contact force (CF), time and AI in both groups.MethodsConsecutive patients undergoing first-time AI-guided ablation with PWI using either 50 W or 35–40 W ablation were enrolled. Acute procedural metrics and individual lesion level ablation data were compared between groups.Results40 patients (50 W: n = 20, 35–40 W: n = 20) with atrial fibrillation were included. Total procedure time was significantly reduced with 50 W (120 vs. 143 mins, p = 0.004) and there was a trend toward decreased ablation time (22 vs. 28 mins, p = 0.052). First pass and acute success of PWI were comparable between the 50 W and 35–40 W groups (10 vs. 8 patients, p = 0.525 and 20 vs. 19 patients, p = 1.000, respectively). Individual lesion analysis of all 959 RF applications (50 W: n = 458, 35–40 W: n = 501) demonstrated that 50 W ablation led to lower ablation time per lesion (10.4 vs. 13.0s, p < 0.001), and increased AI (471 vs. 461, p < 0.001) and impedance drop (7.4 vs. 6.9ohms, p = 0.007). Excessive ablations (AI>600 for roof line; AI>500 elsewhere) were more frequently observed in the 50 W group (9.0% vs. 4.6%, p = 0.007). CF had very good discriminative capability for excessive ablation in both groups. At 50 W, limiting the CF to <10 g reduced the number of excessive ablations on the floor line and within the posterior box to 12% and 4%,respectively. Recurrence of atrial arrhythmias at 12 months were comparable between the groups.ConclusionAI-guided 50 W RF ablation reduces the ablation time of individual lesions and total procedure time without compromising first pass and acute success rates of PWI or 12-month outcomes compared to conventional powers.