Atrial electrogram amplitude variability during atrial fibrillation ablation.

INTRODUCTION: Variability of the bipolar atrial electrogram amplitude may affect voltage maps created during ablation procedures, and thus also the extent of ablations. Therefore, the aim of the study was to assess the beat-to-beat electrogram amplitude variability in the left atrium in patients undergoing atrial fibrillation ablation. METHODS: In 11 patients undergoing ablation for atrial fibrillation, 362 mapping points were collected in two series. At each point, three consecutive beats were recorded and verified including the bipolar electrogram amplitude, contact force (CF), and orientation of the catheter tip. The repeatability and reproducibility of obtained measurements between consecutive beats and series were assessed by the Pearson correlation coefficient (r), the Bland-Altman test, repeatability coefficient (RC), relative standard deviation (RSD), and concordance correlation coefficient (CCC). RESULTS: A total of 1086 beats were analyzed. The correlation coefficient for bipolar atrial electrogram amplitude for the first two beats, and for the first and the third beats were 0.94 and 0.86, respectively. The average of differences between the first two beats and between the first and the third beats were 0.06 and 0.13 mV with 95% limits of agreement (LoA) within ±0.98 and ±1.74 mV, respectively. For CF values ≤5 and ≥20 g, the 95% LoA were narrower compared to other CF ranges and were ±0.49 and ±0.71 mV from the average value, respectively. When the analyzes were performed within the predefined ranges of bipolar electrogram amplitude: 0.05-1; 1-2; 2-3 mV, the 95% LoA were within ±0.33, ±0.98, and ±0.84 mV from the average value, respectively. RC and RSD were 1.41 mV and 20.8%, respectively. For repeated measurement between series, CCC ranged from 0.67 to 0.71 and the 95% LoA were within ±2.7 to 2.9 mV from the average value. CONCLUSION: Bipolar atrial electrogram amplitude recorded at a given site during ablation procedures is variable to an extent that may be clinically relevant. The magnitude of the observed variability is greater during remapping.

Distances between transseptal puncture site and anatomical landmarks.

The aim of the study was to provide quantitative data and to look for new landmarks useful during transseptal puncture (TSP) using a fluoroscopy-guided approach. METHODS AND RESULTS: A total of 104 patients at mean age 57 ± 12 years, of whom 92% underwent pulmonary vein isolation, were analysed. Before TSP catheters were placed in the coronary sinus (CS) and His bundle region. A guidewire running from femoral vein through great veins was left loose in superior vena cava. Before TSP X-ray images were taken in right anterior oblique (RAO) 45° and RAO 53° projections. Locations posterior to TSP site in RAO were described with negative values and those anterior with positive values. The measured distances in millimeters were as follows: (a) between TSP site and posterior atrial wall (RAO 45 = -21 ± 7 mm; RAO 53 = -19 ± 6 mm (b) between TSP site and free guidewire (RAO 45 = -5 ± 4 mm, RAO 53 = -3 ± 4 mm (c) between TSP site and CS ostium (RAO 45 = 9 ± 6 mm; RAO 53 = 8 ± 5 mm (d) between TSP site and His region (RAO 45 = 29 ± 8 mm; RAO 53 = 30 ± 8 mm). We observed correlations between measured distances and age, body mass index and sizes of cardiac chambers. The distance between TSP site and the line projected by the guidewire running between great veins, measured in mid-RAO projections, was very small. CONCLUSION: The distances between TSP site and standard anatomical landmarks used during TSP vary with regard to age, physique and cardiac chamber dimensions. TSP site, as assessed in mid RAO, is in direct vicinity to the line projected by a guidewire running between the great veins.

Wide circumferential versus individual isolation of pulmonary veins using the endoscopic ablation system.

INTRODUCTION: The endoscopic ablation system (EAS) allows for effective pulmonary vein isolation (PVI). The feasibility of wide circumferential as compared to individual PVI using the EAS has not been formally assessed. METHODS: Patients with paroxysmal or short-persistent atrial fibrillation were assigned to individual PVI (group A) or wide circumferential PVI (group B). In group B, circumferential PVI was attempted only if the ipsilateral inferior PV was visualized while the ablation system targeted the superior PV and vice versa. Otherwise, individual PVI was performed. RESULTS: A total of 38 patients were enrolled (Group A: 20 patients, age 61 ± 7 years, LA-diameter 43 ± 5 mm; Group B: 18 patients, age 62 ± 10 years, LA-diameter 43 ± 4 mm). In group A, 20/20 (100%) right superior (RSPV) and inferior (RIPV) PVs, 18/19 (95%) left superior (LSPV) and inferior (LIPV) PVs, and 1/1 (100%) left common ostium (LCPV) were successfully isolated. First-pass success rate was 95%, 85%, 68%, and 95% for the RSPV, RIPV, LSPV, and LIPV, respectively. Touch-up radiofrequency ablation was required in 1/19 (5%) LSPV and LIPV. In group B, an attempt at circumferential PVI was feasible in 2/18 (11%) septal PVs and successful on first pass. Lateral circumferential PVI was attempted and successful on first-pass in 7/13 (54%) LSPVs and LIPVs and 1/5 (20%) LCPVs. CONCLUSIONS: Using the EAS in patients with AF, separate isolation of individual PVs rather than wide circumferential PVI should be the preferred ablation strategy.

Asymptomatic brain lesions following laserballoon-based pulmonary vein isolation.

AIMS: Laserballoon-based pulmonary vein isolation (PVI) for the treatment of atrial fibrillation (AF) has proven safe and effective. Silent brain lesions after AF ablation detected on magnetic resonance imaging (MRI) have been described for several technologies, but its incidence following laserballoon PVI is unknown. The current study sought to assess the incidence of new asymptomatic brain lesions in patients undergoing laserballoon-based PVI. METHODS AND RESULTS: Patients referred for PVI underwent pre- and post-procedural MRI of the brain. A total of 86 patients were enroled into the study (laserballoon group: 44 patients, 15 female, age 63 ± 9 years, left atrial (LA) diameter 43 ± 5 mm; cryoballoon group: 20 patients, 6 female, age 61 ± 9 years, LA diameter 41 ± 4 mm; and irrigated radiofrequency (RF) group: 22 patients, 11 female, age 64 ± 8 years, LA diameter 43 ± 6 mm). There was no statistically significant difference between the groups with regard to new asymptomatic brain lesions detected on post-procedural MRI: 5 of 44 (11.4%) patients in the laserballoon group, 1 of 20 (5.0%) patients in the cryoballoon group, and 4 of 22 (18.2%) patients in the irrigated RF group, respectively. In the laserballoon group, one additional patient with a new cerebral lesion experienced transient diplopia. In a multivariate regression model the only risk factor for asymptomatic new lesions was the CHA2DS2VASc score. CONCLUSION: Following laserballoon-based PVI, new asymptomatic brain lesions were detected in 11.4% of patients. A higher CHA2DS2VASc score, but not the ablation technology utilized, was the only associated risk factor.

Cryoballoon ablation without use of contrast for the treatment of paroxysmal atrial fibrillation.

BACKGROUND: Cryoballoon ablation (CBA) for atrial fibrillation (AF) is usually preceded by demonstrating pulmonary vein (PV) occlusion using contrast. The aim of the study was to determine efficacy and safety of a simplified protocol for CBA performed without demonstrating PV occlusion and compare achieved results with conventional CBA. METHODS: Paroxysmal AF patients undergoing a first-time CBA were prospectively included. In the non-contrast (NC) group CBA was performed using standardized protocol without demonstrating PV occlusion. In the conventional contrast (CC) group ablations were performed after confirmation of PV occlusion. RESULTS: The NC and CC groups comprised 51 and 22 patients, respectively. PVI according to the group assignment was achieved in 34 (67%) and 21 (95.5%) patients from the NC and CC groups, respectively (p < 0.001). In the NC group, 184 (90%) out of 204 veins were isolated without venography. There were no differences between the NC and CC groups in terms of procedure duration (89.7 ± 22.6 vs. 90.0 ± 20.6 min; p = 0.7) and fluoroscopy time (15.3 ± 6.3 vs. 15 ± 4.5 min; p = 0.8). In the NC group, the use of contrast was significantly lower compared to the CC group (4.9 ± 10.1 vs. 19.4 ± 8.6 mL, p < 0.001). There were no serious adverse events in both groups. A 1-year freedom from AF was achieved in 73.5% and 71.5% of patients from the NC and CC groups, respectively (p = 1). CONCLUSIONS: Cryoballoon ablation without demonstrating vein occlusion with contrast is safe and feasible. Proposed simplified approach enables isolation of the vast majority of pulmonary veins with a significant reduction in the amount of contrast used.

Bipolar Endo-Epicardial Radiofrequency Ablation of Therapy-Resistant Ventricular Arrhythmias: A Brief Case Series.

Despite extensive conventional endoepicardial ablation, significant intramural arrhythmogenic substrate may remain out of reach of unipolar radiofrequency ablation (RFA). The authors present clinical findings and procedural workflow for bipolar radiofrequency ablation (B-RFA) with 1 catheter placed against the endocardium and the other in the pericardial sac to ablate refractory ventricular arrhythmias. No serious adverse events occurred during B-RFA procedures, and the short-term and midterm clinical results were satisfactory. Optimal catheter choice and ablation parameters settings for B-RFA remain to be determined.

Safety and Efficacy of a Novel Blunt-Tip Concealed-Needle Epicardial Access Device: First-in-Human Feasibility Study.

Epicardial access is becoming increasingly important for various cardiovascular interventions. Access to dry pericardial space can be challenging and is often associated with significant complications. A novel concealed-needle blunt-tip device is designed to capture the parietal pericardium layer and retract it into the distal end of the device, which houses a fixated concealed needle, in a bid to minimize the likelihood of lacerating the visceral layer of the pericardium. This prospective single-arm study evaluated the feasibility of use of this device in 11 human subjects with successful access attained in 91% (10 of 11) of cases without adverse events. (Pericardial Access With ViaOne Device; NCT05006157).

Simultaneous Entrainment Response Assessment at Multiple Sites.

BACKGROUND: The entrainment response, defined as the difference between the postpacing interval and the tachycardia cycle length (TCL) recorded from a mapping catheter, allows to track down the components of the tachycardia loop. OBJECTIVES: The aim of this study was to evaluate if the postpacing interval measured simultaneously from multiple sites that are remote from the pacing site (PPIR) could be clinically useful in mapping re-entrant circuits. METHODS: Ninety-two episodes of entrainment response in 29 patients with different macro-re-entrant tachycardias were evaluated using a standardized entrainment protocol. The spatial distribution of different values of PPIR-TCL in a simulation and a computational model of an entrained re-entrant tachycardia was also analyzed. RESULTS: The PPIR exceeded TCL by more than 20 milliseconds only if both pacing and recording sites were outside the tachycardia circuit. The PPIR-TCL at in-circuit sites was always ≤20 milliseconds. Sites with negative PPIR-TCL values were found either outside or inside the tachycardia circuit. CONCLUSIONS: Assessment of entrainment response from catheters remote from the pacing site may enhance spatial mapping of the tachycardia circuit. The PPIR-TCL above 20 milliseconds has an excellent positive predictive value in identifying sites outside the tachycardia circuit.

A New Era in Epicardial Access for the Ablation of Ventricular Arrhythmias: The Epi-Co2 Registry.

OBJECTIVES: This multicenter registry aimed to assess the reproducibility and safety of intentional coronary vein exit and carbon dioxide insufflation to facilitate subxiphoid epicardial access in the setting of ventricular tachycardia ablation. BACKGROUND: Epicardial ablation for ventricular tachycardia is not a widespread technique due to the significant potential complications associated with subxiphoid puncture. The first experience in 12 patients showed that intentional coronary vein exit and carbon dioxide insufflation was technically feasible. METHODS: A branch of the coronary sinus was cannulated by means of a diagnostic JR4 coronary catheter. Intentional perforation at the distal portion of that branch was performed with a high tip load 0.014-inch angioplasty wire. A microcatheter was advanced over the wire into the pericardial space. Carbon dioxide was then insufflated into the pericardial space, allowing direct visualization of the anterior pericardial space to facilitate subxiphoid puncture. RESULTS: Intentional coronary vein exit was attempted in 102 consecutive patients in 16 different centers and successfully completed in 101 patients. Significant pericardial adhesions were confirmed in 3 patients, preventing carbon dioxide insufflation and epicardial ablation. None of the punctures were complicated with inadvertent right ventricular puncture or damage to a coronary artery. Significant bleeding (>80 ml) due to coronary vein exit occurred in 5 patients, without hemodynamic compromise. None of the patients required surgery. CONCLUSIONS: Coronary vein exit and carbon dioxide insufflation can be safely and reproducibly achieved to facilitate subxiphoid pericardial access in the setting of ventricular tachycardia ablation.

[Ablation of right ventricular tachycardia with a bizarre QRS complex--a case report]. / Ablacja czestoskurczu z prawej komory o niezwyklym ksztalcie QRS--opis przypadku.

We describe a case of a 77-year-old patient with recurrent, symptomatic ventricular tachycardia with a bizarre QRS complex originating from the right ventricle lateral wall. The small region of slow conduction was the critical substrate for initiation and maintenance of ventricular tachycardia, confirmed by a successful one RF application.

[QRS and cycle length alternans during atrioventricular nodal reentry tachycardia: case report]. / Zmiennosc ksztaltu zespolów QRS i dlugosci cyklu w nawrotnym czestoskurczu wezlowym. Opis przypadku.

A 23-year old man with paroxysmal, poorly tolerated and spontaneously terminating palpitations, was referred to our department for electrophysiological study. Burst pacing from high right atrium using a cycle length of 350 ms induced a slowfast atrioventricular nodal reentry tachycardia. We excluded the presence of accessory atrioventricular tracts. During tachycardia a constant alternans of QRS morphology and cycle length was observed. The cycle length alternans could be due to the presence of three nodal pathways and activation circulating in a figure-of-eight pattern using alternatively two slow pathways as the antegrade arm of the reentry loop. The alternans could also originate from altering decremental properties of a single slow pathway that changed its conduction properties with relation to the length of the preceding cycle. The QRS alternans occurred both during burst pacing and tachycardia. As it was related to the rate and the changing cycle length, we concluded that it could reflect aberration in intraventricular conduction.

[RF ablation in a patient with recurrent post-infarction ventricular tachycardia requiring multiple cardioverter-defibrillator interventions]. / Ablacja RF u chorego z wielokrotnymi interwencjami kardiowertera-defibrylatora z powodu pozawalowego czestoskurczu komorowego.

A case of a 51 year old patient with a history of myocardial infarction (MI) and recurrent ventricular tachycardia (VT) is presented. Three months after MI the patient underwent coronary angioplasty and one year later received prophylactic implantable cardioverter-defibrillator (ICD) due to complex ventricular arrhythmias, detected on Holter ECG monitoring, and depressed left ventricular ejection fraction. Later on the patient started to experience palpitations and ICD shocks during physical activity (cycling). Interrogation of the ICD memory showed appropriate shocks due to slow (160 betas/min) VT. The device was reprogrammed and new antitachycardia pacing (ATP) algorithms were enabled, however, it occurred proarrhythmic due to the ATP-induced acceleration of VT rate. Finally, in April 2005 he received 37 appropriate ICD shocks during a few hours. The patient was selected for RF ablation and underwent successful procedure with the use of the electro-anatomical CARTO mapping system.

In vivo contact force analysis and correlation with tissue impedance during left atrial mapping and catheter ablation of atrial fibrillation.

BACKGROUND: The aim of this study was to evaluate in vivo contact force (CF) and the correlation of CF with impedance during left atrial 3-dimensional electroanatomical mapping and ablation. METHODS AND RESULTS: CF during point-by-point left atrial mapping was assessed in 30 patients undergoing atrial fibrillation ablation. Operators were blinded to the real-time CF data. Data were analyzed according to 11 predefined areas in the left atrial and 6 segments around the ipsilateral pulmonary veins. A total of 3475 mapping and 878 ablation points were analyzed. Median CF during mapping was 14.0g (6.5-26.2; q1-q3), ranging from 5.1g at the ridge to 29.8g at the roof. Median CF at the ridge and mitral isthmus were 5.1g and 6.9g, respectively. Extremely high CF ≥100g was noted in 24 points (0.7%). Median CFs during ablation around the right and left pulmonary veins were 22.8g (12.6-37.9; q1-q3) and 12.3g (6.9-30.2; q1-q3), respectively. The lowest median CFs were recorded at the anterior-superior and anterior-inferior segments of the left pulmonary veins (7.2g and 7.9g). Impedance values during mapping and impedance fall during ablation correlated with the applied CF (R(2)=0.16; P<0.001 and R(2)=0.04; P<0.001) although there was significant overlap. CONCLUSIONS: Excessively high and low CF values can be observed during left atrial mapping and ablation. The low CF obtained at the mitral isthmus and anterior segments of the left pulmonary veins may explain why reconnection after ablation occurs more frequently at these sites. CF and impedance do correlate; however, the impedance for a given CF ranges widely, limiting its use in clinical practice.

[Reentrant ventricular tachycardia treated with RF ablation delivered through coronary sinus - a case report]. / Burza elektryczna w przebiegu ustawicznego nawrotnego czestoskurczu komorowego o lokalizacji epikardialnej skutecznie leczonego ablacja RF z dojscia przez zatoke wiencowa.

A case of a 58 year-old man with epicardially located reentrant ventricular tachycardia treated with RF ablation delivered through coronary sinus is presented. Based on multiple electrophysiological parameters (surface ECG, electroanatomical map collected from the endocardium, bipolar and unipolar endocardial recordings, and unsuccesful ablation attempts from the endocardial side) the tachycardia loop was found to be located epicardially. This allowed for successful ablation approach.