Acute and long-term results with the 3rd generation visually guided laser balloon ablation system for pv isolation.

BACKGROUND: Visually guided laser balloon ablation is known as an effective pulmonary vein (PV) isolation device. The third-generation laser balloon ablation system (X3) equipped with compliant balloon and an automated motor-driven laser output mechanism, namely RAPID mode, has been clinically proven for PV isolation. METHODS: PV isolation with X3 was performed in all the patients with paroxysmal and early-stage persistent atrial fibrillation (AF). Acute data for PV isolation and clinical outcomes including supraventricular tachyarrhythmia (SVT: AF, atrial flutter, or atrial tachycardia)-free survival rate beyond 1 year were analyzed. RESULTS: A total of 110 patients (62 ± 13 years old, 80% of paroxysmal AF) were treated with X3. RAPID mode with was utilized to achieve PV isolation in all cases. In combination with RAPID mode and spot mode laser ablation, 91.1% (380/417) of veins were isolated on the first circumferential lesion set and did not require touch-up ablation and during the index procedure 100% of attempted veins were isolated. The mean procedure time was 77.0 ± 22.7 min and LA dwell time was 61.9 ± 22.0 min. Total duration of laser application was 5.1 ± 2.3 min per vein. At 1 year, SVT-free survival rate was 93.7% in paroxysmal AF patients, and 81.1% in persistent AF patients. CONCLUSIONS: A novel continuous automatic laser balloon ablation system was proved to be safe and effective for both paroxysmal and persistent AF patients. The clinical result demonstrated that PV isolation with X3 could achieve a high SVT-free survival rate.

Provocation and Localization of Arrhythmogenic Triggers from Persistent Left Superior Vena Cava in Patients with Atrial Fibrillation.

BACKGROUND: Although pulmonary vein isolation (PVI) is an established procedure for atrial fibrillation (AF), non-PV foci play a crucial role in AF recurrence. Persistent left superior vena cava (PLSVC) has been reported as critical non-PV foci. However, the effectiveness of provocation of AF triggers from PLSVC remains unclear. This study was designed to validate the usefulness of provoking AF triggers from PLSVC. METHODS: This multicenter retrospective study included 37 patients with AF and PLSVC. To provoke triggers, AF was cardioverted, and re-initiation of AF was monitored under high-dose isoproterenol infusion. The patients were divided into two groups: those whose PLSVC had arrhythmogenic triggers initiating AF (Group A) and those whose PLSVC did not have triggers (Group B). Group A underwent isolation of PLSVC after PVI. Group B received PVI only. RESULTS: Group A had 14 patients, whereas Group B had 23 patients. After a 3-year follow-up, no difference in the success rate for maintaining sinus rhythm was observed between the two groups. Group A was significantly younger and had lower CHADS2-VASc scores than Group B. CONCLUSIONS: The provocation of arrhythmogenic triggers from PLSVC was effective for the ablation strategy. PLSVC electrical isolation would not be necessary if arrhythmogenic triggers are not provoked.

Pulsed Field Ablation to Treat Atrial Fibrillation: Autonomic Nervous System Effects.

BACKGROUND: During atrial fibrillation ablations using thermal energy, the treatment effect is attributed to not just pulmonary vein isolation (PVI), but also to modulation of the autonomic nervous system by ablation of cardiac ganglionated plexi (GP). OBJECTIVES: This study sought to assess the impact of pulsed field ablation (PFA) on the GP in patients undergoing PVI. METHODS: In the retrospective phase, heart rate was assessed pre- versus post-PVI using PFA, cryoballoon ablation, or radiofrequency ablation. In the prospective phase, a pentaspline PFA catheter was used in a protocol: 1) pre-PFA, high-frequency stimulation (HFS) identified GP sites by vagal effects; 2) PVI was performed assessing for repetitive vagal effects over each set of PF applications; 3) mapping defined PVI extent to identify those GP in the ablation zone; and 4) repeat HFS at GP sites to assess for persistence of vagal effects. RESULTS: Between baseline and 3 months, heart rates in the retrospective radiofrequency ablation (n = 40), cryoballoon (n = 40), and PFA (n = 40) cohorts increased by 8.9 ± 11.4, 11.1 ± 9.4, and -0.1 ± 9.2 beats/min, respectively (P= 0.01 PFA vs radiofrequency ablation; P= 0.01 PFA vs cryoballoon ablation). In the prospective phase, pre-PFA HFS in 20 additional patients identified 65 GP sites. During PFA, vagal effects were noted in 45% of first PF applications, persisting through all applications in 83%. HFS post-PFA reproduced vagal effects in 29 of 38 sites (76%) in low-voltage tissue. CONCLUSIONS: PFA has minimal effect on GP. Unlike with thermal ablation, the mechanism by which PFA treats atrial fibrillation is mediated solely by durable PVI.

Screening of Fabry disease in patients with an implanted permanent pacemaker.

BACKGROUND: Anderson-Fabry disease (AFD) is an X-linked inherited lysosomal disease caused by a defect in the gene encoding lysosomal enzyme α-galactosidase A (GLA). Atrio-ventricular (AV) nodal conduction defects and sinus node dysfunction are common complications of the disease. It is not fully elucidated how frequently AFD is responsible for acquired AV block or sinus node dysfunction and if some AFD patients could manifest primarily with spontaneous bradycardia in general population. The purpose of study was to evaluate the prevalence of AFD in male patients with implanted permanent pacemaker (PM). METHODS: The prospective multicentric screening in consecutive male patients between 35 and 65 years with implanted PM for acquired third- or second- degree type 2 AV block or symptomatic second- degree type 1 AV block or sinus node dysfunction was performed. RESULTS: A total of 484 patients (mean age 54 ± 12 years at time of PM implantation) were enrolled to the screening in 12 local sites in Czech Republic. Out of all patients, negative result was found in 481 (99%) subjects. In 3 cases, a GLA variant was found, classified as benign: p.Asp313Tyr, p.D313Y). Pathogenic GLA variants (classical or non-classical form) or variants of unclear significance were not detected. CONCLUSION: The prevalence of pathogenic variants causing AFD in a general population sample with implanted permanent PM for AV conduction defects or sinus node dysfunction seems to be low. Our findings do not advocate a routine screening for AFD in all adult males with clinically significant bradycardia.

Coronary Arterial Spasm During Pulsed Field Ablation to Treat Atrial Fibrillation.

BACKGROUND: Pulsed field ablation (PFA) has a unique safety profile when used to treat atrial fibrillation, largely related to its preferentiality for myocardial tissue ablation, in particular, esophageal sparing. A pentaspline catheter was the first such PFA system studied clinically for atrial fibrillation ablation; in these initial regulatory trials, the catheter was used for pulmonary vein isolation and left atrial posterior wall ablation. Since its regulatory approval in Europe, in clinical practice, physicians have ablated beyond pulmonary vein isolation and left atrial posterior wall ablation to expanded lesion sets in closer proximity to coronary arteries. This is an unstudied important issue because preclinical and clinical data have raised the potential for coronary arterial spasm. Herein, we studied the vasospastic potential of PFA lesion sets, both remote from and adjacent to coronary arteries. METHODS: During routine atrial fibrillation ablation using the pentaspline PFA catheter, coronary angiography was performed before, during, and after pulsed field applications. The lesion sets studied included: (1) those remote from the coronary arteries such as pulmonary vein isolation (n=25 patients) and left atrial posterior wall ablation (n=5), and (2) ablation of the cavotricuspid isthmus (n=20) that is situated adjacent to the right coronary artery. RESULTS: During pulmonary vein isolation and left atrial posterior wall ablation, coronary spasm did not occur, but cavotricuspid isthmus ablation provoked severe subtotal vasospasm in 5 of 5 (100%) consecutive patients, and this was relieved by intracoronary nitroglycerin in 5.5±3.5 minutes. ST-segment elevation was not observed. However, no patient (0%, P=0.004) had severe spasm if first administered parenteral nitroglycerin, either intracoronary (n=5) or intravenous (n=10), before treatment. CONCLUSIONS: Coronary vasospasm was not provoked during PFA at locations remote from coronary arteries, but when the energy is delivered adjacent to a coronary artery, PFA routinely provokes subclinical vasospasm. This phenomenon is attenuated by nitroglycerin, administered either post hoc to treat spasm or as prophylaxis.

Left bundle branch area pacing outcomes: the multicentre European MELOS study.

AIMS: Permanent transseptal left bundle branch area pacing (LBBAP) is a promising new pacing method for both bradyarrhythmia and heart failure indications. However, data regarding safety, feasibility and capture type are limited to relatively small, usually single centre studies. In this large multicentre international collaboration, outcomes of LBBAP were evaluated. METHODS AND RESULTS: This is a registry-based observational study that included patients in whom LBBAP device implantation was attempted at 14 European centres, for any indication. The study comprised 2533 patients (mean age 73.9 years, female 57.6%, heart failure 27.5%). LBBAP lead implantation success rate for bradyarrhythmia and heart failure indications was 92.4% and 82.2%, respectively. The learning curve was steepest for the initial 110 cases and plateaued after 250 cases. Independent predictors of LBBAP lead implantation failure were heart failure, broad baseline QRS and left ventricular end-diastolic diameter. The predominant LBBAP capture type was left bundle fascicular capture (69.5%), followed by left ventricular septal capture (21.5%) and proximal left bundle branch capture (9%). Capture threshold (0.77 V) and sensing (10.6 mV) were stable during mean follow-up of 6.4 months. The complication rate was 11.7%. Complications specific to the ventricular transseptal route of the pacing lead occurred in 209 patients (8.3%). CONCLUSIONS: LBBAP is feasible as a primary pacing technique for both bradyarrhythmia and heart failure indications. Success rate in heart failure patients and safety need to be improved. For wider use of LBBAP, randomized trials are necessary to assess clinical outcomes.

Pulsed Field Ablation of Paroxysmal Atrial Fibrillation: 1-Year Outcomes of IMPULSE, PEFCAT, and PEFCAT II.

OBJECTIVES: This study sought to determine whether durable pulmonary vein isolation (PVI) using pulsed field ablation (PFA) translates to freedom from atrial fibrillation recurrence without an increase in adverse events. BACKGROUND: PFA is a nonthermal ablative modality that, in preclinical studies, is able to preferentially ablate myocardial tissue with minimal effect on surrounding tissues. Herein, we present 1-year clinical outcomes of PFA. METHODS: In 3 multicenter studies (IMPULSE [A Safety and Feasibility Study of the IOWA Approach Endocardial Ablation System to Treat Atrial Fibrillation], PEFCAT [A Safety and Feasibility Study of the FARAPULSE Endocardial Ablation System to Treat Paroxysmal Atrial Fibrillation], and PEFCAT II [Expanded Safety and Feasibility Study of the FARAPULSE Endocardial Multi Ablation System to Treat Paroxysmal Atrial Fibrillation]), paroxysmal atrial fibrillation patients underwent PVI using a basket or flower PFA catheter. Invasive remapping was performed at ∼2 to 3 months, and reconnected PVs were reisolated with PFA or radiofrequency ablation. After a 90-day blanking period, arrhythmia recurrence was assessed over 1-year follow-up. RESULTS: In 121 patients, acute PVI was achieved in 100% of PVs with PFA alone. PV remapping, performed in 110 patients at 93.0 ± 30.1 days, demonstrated durable PVI in 84.8% of PVs (64.5% of patients), and 96.0% of PVs (84.1% of patients) treated with the optimized biphasic energy PFA waveform. Primary adverse events occurred in 2.5% of patients (2 pericardial effusions or tamponade, 1 hematoma); in addition, there was 1 transient ischemic attack. The 1-year Kaplan-Meier estimates for freedom from any atrial arrhythmia for the entire cohort and for the optimized biphasic energy PFA waveform cohort were 78.5 ± 3.8% and 84.5 ± 5.4%, respectively. CONCLUSIONS: PVI with a "single-shot" PFA catheter results in excellent PVI durability and acceptable safety with a low 1-year rate of atrial arrhythmia recurrence. These data mitigate concern that the nonthermal ablative mechanism of PFA might mask undiscovered compromises to clinical success. (IMPULSE: A Safety and Feasibility Study of the IOWA Approach Endocardial Ablation System to Treat Atrial Fibrillation, NCT03700385; A Safety and Feasibility Study of the FARAPULSE Endocardial Ablation System to Treat Paroxysmal Atrial Fibrillation, NCT03714178; PEFCAT II Expanded Safety and Feasibility Study of the FARAPULSE Endocardial Multi Ablation System to Treat Paroxysmal Atrial Fibrillation [PEFCAT II], NCT04170608).

Retrieval of Long-Term Implanted Leadless Pacemakers: A Single-Center Experience.

OBJECTIVES: The authors report their single-center experience with the retrieval and replacement of long-term implanted leadless cardiac pacemakers (LPs) and the factors contributing to success. BACKGROUND: LPs are a clinically effective and safe alternative to standard transvenous pacemakers for single-chamber ventricular pacing. However, the feasibility of retrieving and replacing long-term implanted LPs is not well known. METHODS: A total of 34 patients with implanted Nanostim LPs (mean implantation duration 1,570 ± 479 days) subsequently underwent retrieval. On the basis of fluoroscopic imaging, the cohort was divided into 2 groups: those with remarkable swinging movement (SM) of the LP docking button (n = 25) and those without SM (n = 9). RESULTS: The overall LP retrieval success rate was 85% (n = 29). New leadless devices were implanted in 27 patients immediately after LP retrieval. No procedure-related adverse events occurred. The rate of successful LP retrieval was significantly higher in the SM group (25 of 25 [100%]) than in the no-SM group (4 of 9 [44%]) (p < 0.001), and fluoroscopy time during the retrieval procedure was shorter in the SM group (12.7 ± 8.6 min) than in the no-SM group (45.6 ± 19 min) (p < 0.001). CONCLUSIONS: This study demonstrated the feasibility and safety of retrieval of long-term implanted LPs after a mean duration of 4 years. Retrieval was most successful in patients whose docking buttons exhibited significant SM.

His bundle pacing after failure of cardiac resynchronization therapy: a case study.

His bundle pacing is a relatively new method of cardiac pacing. This method is used in patients with atrioventricular block to prevent heart failure associated with right ventricular pacing, and in patients with bundle branch block and cardiomyopathy. We report a patient with cardiomyopathy and left bundle branch block with failure of cardiac resynchronization therapy. Permanent His bundle pacing was associated with clinical improvement and improvement of parameters of cardiac function.

Successful Retrieval of a 4-Year-Old Micra Transcatheter Pacemaker System in a Patient With Leadless Biventricular Pacing Therapy.

This is the first report of the management of a patient with cardiac resynchronization therapy using leadless biventricular pacing. Successful retrieval of a 4-year-old Micra transcatheter pacing system (TPS) and reimplantation of a new Micra TPS prevented device-to-device interactions from multiple pacing devices in the right ventricle. (Level of Difficulty: Advanced.).

Pulsed Field Ablation for Pulmonary Vein Isolation in Atrial Fibrillation.

BACKGROUND: Catheter ablation of atrial fibrillation using thermal energies such as radiofrequency or cryothermy is associated with indiscriminate tissue destruction. During pulsed field ablation (PFA), subsecond electric fields create microscopic pores in cell membranes-a process called electroporation. Among cell types, cardiomyocytes have among the lowest thresholds to these fields, potentially permitting preferential myocardial ablation. OBJECTIVES: The purpose of these 2 trials was to determine whether PFA allows durable pulmonary vein (PV) isolation without damage to collateral structures. METHODS: Two trials were conducted to assess the safety and effectiveness of catheter-based PFA in paroxysmal atrial fibrillation. Ablation was performed using proprietary bipolar PFA waveforms: either monophasic with general anesthesia and paralytics to minimize muscle contraction, or biphasic with sedation because there was minimal muscular stimulation. No esophageal protection strategy was used. Invasive electrophysiological mapping was repeated after 3 months to assess the durability of PV isolation. RESULTS: In 81 patients, all PVs were acutely isolated by monophasic (n = 15) or biphasic (n = 66) PFA with ≤3 min elapsed delivery/patient, skin-to-skin procedure time of 92.2 ± 27.4 min, and fluoroscopy time of 13.1 ± 7.6 min. With successive waveform refinement, durability at 3 months improved from 18% to 100% of patients with all PVs isolated. Beyond 1 procedure-related pericardial tamponade, there were no additional primary adverse events over the 120-day median follow-up, including: stroke, phrenic nerve injury, PV stenosis, and esophageal injury. The 12-month Kaplan-Meier estimate of freedom from arrhythmia was 87.4 ± 5.6%. CONCLUSIONS: In first-in-human trials, PFA preferentially affected myocardial tissue, allowing facile ultra-rapid PV isolation with excellent durability and chronic safety. (IMPULSE: A Safety and Feasibility Study of the IOWA Approach Endocardial Ablation System to Treat Atrial Fibrillation; NCT03700385; and PEFCAT: A Safety and Feasibility Study of the FARAPULSE Endocardial Ablation System to Treat Paroxysmal Atrial Fibrillation; NCT03714178).

Left Atrial Appendage Closure Under Intracardiac Echocardiographic Guidance: Feasibility and Comparison With Transesophageal Echocardiography.

BACKGROUND: Transcatheter left atrial appendage closure is an alternative therapy for stroke prevention in atrial fibrillation patients. These procedures are currently guided with transesophageal echocardiography and fluoroscopy in most centers. As intracardiac echocardiography (ICE) is commonly used in other catheter-based procedures, we sought to determine the safety and effectiveness of intracardiac echocardiography-guided left atrial appendage closure with the Watchman device. METHODS AND RESULTS: A total of 27 patients (11 males, 77.0±8.5 years) with atrial fibrillation receiving Watchman left atrial appendage closure under intracardiac echocardiography guidance at a single center were investigated. All patients were implanted successfully. There were no major procedural complications. The overall procedure-related complication rate was 14.8%, mainly due to access site hematoma. Transesophageal echocardiography demonstrated successful closure of the left atrial appendage in all patients at 45 days after device implant. CONCLUSIONS: Transcatheter left atrial appendage closure with intracardiac echocardiography guidance is safe and feasible.

Catheter Ablation of Ischemic Ventricular Tachycardia With Remote Magnetic Navigation: STOP-VT Multicenter Trial.

INTRODUCTION: Catheter ablation is an effective treatment of scar-related ventricular tachycardia (VT), but the overall complexity of the procedure has precluded its widespread use. Remote magnetic navigation (RMN) has been shown to facilitate cardiac mapping and ablation of VT in a retrospective series. STOP-VT is the first multicenter, prospective, single-arm and single-procedure study evaluating RMN-based mapping and ablation of post-infarction VT. METHODS: Patients with documented VT and prior MI, in whom an ICD was implanted either for primary or secondary prevention, were recruited from four EU and US centers. Either a transseptal (48 patients) or transaortic (5 patients) approach was employed to gain access for ventricular endocardial mapping/ablation during VT (entrainment mapping, activation mapping) and/or substrate mapping in sinus rhythm (elimination of fractionated/late potentials, variable extent of substrate modification) with RMN and irrigated RF ablation. The primary endpoints were as follows: (i) non-inducibility of the target VT or any other sustained VT; (ii) elimination of sustained VT/VF during ICD follow-up of up to 12 months. RESULTS: The cohort included 53 consecutive patients (median age 67 years, 49 men, median LVEF 31%). One hemodynamically unstable patient was excluded at the onset of mapping. Inducibility of sustained VT was achieved an average of 2.2 times per patient (1-8), with mean tachycardia cycle length (TCL) 374 milliseconds (179-510). Mean total procedure and fluoroscopy times were 223 minutes and 8.7 minutes, respectively; mean cumulative fluoroscopy time during mapping and ablation was 0.95 minutes; maximum power averaged 42.3 W with nominal saline 30 cc/min irrigation; mean cumulative RF time was 38 minutes. Non-inducibility of the target VT was achieved in 49/52 patients (94.2%) and non-inducibility of any VT was achieved in 38/52 patients (73.1%). A combination of RMN and manual ablation was performed in two patients, rendering one non-inducible. During the 12-month ICD follow-up period, freedom from any sustained VT/VF was observed in 30 patients (62%), of which 19 (63%) were off antiarrhythmic medications. Five patients expired during follow-up: one presented with a VT storm, but for the others, death was not related to VT/VF (MI-cardiogenic shock, pulmonary embolism, bronchogenic carcinoma, end stage heart failure). No procedural complications were reported. CONCLUSIONS: This first prospective, single-procedure, multicenter study indicates that remote magnetic navigation is a safe and effective method for catheter ablation of post-infarction VT.

Anatomical predictors for successful pulmonary vein isolation using balloon-based technologies in atrial fibrillation.

PURPOSE: We evaluated the correlation between pulmonary venous (PV) anatomy and acute and long-term success of PV isolation (PVI) with two balloon-based ablation catheter techniques. METHODS: One hundred consecutive patients were analyzed in two equal groups treated with either the second-generation cryoballoon (CRYO) catheter or the visually guided laser ablation (VGLA) catheter. All patients underwent multi-detector computed tomography (CT) imaging. The primary and secondary efficacy endpoints were the procedural achievement of proven electrical isolation of all veins and freedom from atrial fibrillation (AF) within a 1-year follow-up period, respectively. RESULTS: Variant PV anatomy was observed in 32% of patients in the CRYO group and in 40% of patients in the VGLA group. All PVs were targeted with either the CRYO catheter (n = 199) or the VGLA catheter (n = 206). One hundred ninety-three of 199 PVs (97%) were successfully isolated in the CRYO group and 194 of 206 PVs (94%) in the VGLA group (p = 0.83). Over a 12-month follow-up, AF recurrence was documented in 11/45 (24%) and 7/43 (16%) patients in the CRYO and the VGLA groups, respectively (p = 0.21). In the CRYO group, a larger left inferior PV size was associated with worse long-term outcome (p = 0.001). In the VGLA group, a larger left superior PV size (p = 0.003) and more oval right inferior PV were associated with worse acute success (p = 0.038). There was no absolute cutoff between PV anatomy and clinical success. CONCLUSIONS: The variability of PV anatomy did not significantly compromise acute success of PVI or patient outcomes.

Durability of Pulmonary Vein Isolation with Cryoballoon Ablation: Results from the Sustained PV Isolation with Arctic Front Advance (SUPIR) Study.

INTRODUCTION: Pulmonary vein (PV) reconnection remains the most important cause of AF recurrence after AF ablation. The second-generation cryoballoon catheter's ability to achieve durable PV isolation was assessed in a prospective nonrandomized clinical trial. METHODS AND RESULTS: PV isolation was performed by 4-minute ablations. Following verification of electrical isolation by a multielectrode mapping catheter, 1 additional lesion per PV was applied. Esophageal temperatures were monitored and all patients underwent postprocedure esophageal endoscopy. All patients underwent a second PV remapping procedure at ∼3 months to assess for PVI durability. Eighty-four (100%) veins were acutely isolated using only the 28 mm cryoballoon in 21 consecutive PAF patients with 2.2 ± 0.6 cryoapplications per vein, with the majority (83%) occurring after a single freeze. One patient presented with hematemesis and an esophageal ulceration that was treated conservatively; there were no episodes of esophageal fistula or phrenic nerve palsy. At 3.4 (2.9-4.1) months postablation, 68/75 veins (91%) remained electrically isolated; all PVs remained durably isolated in 79% of patients. Two patients accounted for 5 of 7 reconducting veins. The most common site for reconnection was the inferior aspect of the RIPV (3/7 reconnections). Reconnected veins had poorer occlusion at the index ablation procedure than veins that maintained chronic isolation (occlusion grade 2.9 ± 0.7 vs. 3.4 ± 0.7, P = 0.001). Clinical AF recurrence was detected in 2 patients (11%) at follow-up. CONCLUSIONS: The improved thermodynamic characteristics of the second-generation cryoballoon led to a high rate of both single-shot PVI and chronic lesion durability. This high rate of durable PV isolation is anticipated to translate to improved clinical outcome.

Visually guided laser ablation: a single-centre long-term experience.

AIMS: Durable isolation of the pulmonary veins (PVs) remains the cornerstone of treatment for paroxysmal atrial fibrillation (PAF) and is also used in the treatment of some patients with persistent atrial fibrillation. Visually guided laser ablation (VGLA) has been proven to be safe and effective as a treatment for atrial fibrillation (AF). It has shown high levels of durable PV isolation (PVI), even in the hands of less experienced users. This paper presents the long-term clinical outcomes of all patients treated with VGLA over the course of 4 years in the world's most experienced centre: from early product feasibility work treating only PAF patients to our work using the commercially available product, when we also treated persistent AF patients. METHODS AND RESULTS: One hundred and ninety-four patients (63 females, mean age 61 years) with either a history of drug-refractory PAF (time since initial diagnosis: 60.73 months) or persistent AF (time since initial diagnosis: 62.75 months) were treated in our laboratory with VGLA between 7 January 2009 and 17 May 2013. Follow-up of all patients was consistent with our standard clinical practice with a 7-day Holter being performed at the first clinical visit between 4 and 6 months and, for most patients, again at 12 months post-procedure. Twelve lead electrocardiograms were performed at all clinical visits. Recurrence of AF is defined as any documented AF episode >30 s. Acute procedural results show that 692 veins were acutely isolated with a mean procedure and fluoroscopy time of 226 and 20.4 min, respectively. One hundred and seventy (158 PAF and 12 persistent AF) patients reached 1 year of follow-up, 130 (82.3%) patients remained free of AF in the PAF group, and 9 (75%) in the persistent group. Eighty-seven PAF patients have now reached 24 months follow-up and 66 (75.9%) remain free of AF. Fifty-four PAF patients have reached 36 months follow-up with 41 (75.9%) remaining free of AF. Thirty-two PAF patients have reached 48 months follow-up and 24 (75%) remain free of AF. The peri-procedural complications we encountered were phrenic nerve injury in four patients (2.06%), tamponade or pericardial effusion in one patient (0.51%), stroke or transient ischaemic attack in one patient (0.514%), and vascular injury in six patients (3.09%). We experienced no cases of PV stenosis or atrio-oesophageal fistula. CONCLUSION: Our single-centre experience using VGLA over 4 years shows that it can be used safely and effectively in normal clinical practice and gives high levels of acute PVI accompanied by good clinical outcomes, even after long-term follow-up.

[Role of reactive oxygen species and nitric oxide in development of the hypoxic pulmonary hypertension]. / Vztah volných kyslíkových radikálu a oxidu dusnatého pri vzniku hypoxické plicní hypertenze.

Pulmonary circulation is completely different compared to systemic circulation. Chronic hypoxia damages peripheral pulmonary arterioles and causes hypoxic pulmonary hypertension (HPH) which consists of vasoconstriction and remodelling of the arterioles. The release of reactive oxygen species (ROS)--mainly superoxide and nitric oxide (NO) contribute to the pathogenesis of HPH. During exposition to chronic hypoxia, the NO production is markedly elevated and it has two effects: the first, direct vasodilatory effect caused by NO, the second, contribution to remodelling of the peripheral pulmonary vessels by interaction with ROS. The interaction of superoxid and NO releases peroxynitrite which plays a role in the onset of collagen cleavage. A typical low molecular weight of collagen fragments induces remodelling of the peripheral pulmonary arterioles. These changes are typical for the first week of exposure to the chronic hypoxia which also correlates with sudden elevation of the mean pulmonary artery pressure. Continual exposition to the chronic hypoxia after first week does not cause progressive worsening of HPH.