Pathological effects of extensive radiofrequency energy applications in the pulmonary veins in dogs

Intravascular Shockwave Lithotripsy: An Adjunct to Balloon Angioplasty for Calcified Pulmonary Vein Stenosis

Pulmonary vein stenosis occurs in 0.4% to 2% of cases after atrial fibrillation ablation. Patients experience chest pain or shortness of breath when pulmonary vein narrowing exceeds 60% or its diameter falls below 4 to 6 mm. To our knowledge, this is the first case report of the use of shockwave intravascular lithotripsy to address calcified pulmonary vein stenosis after the conventional approach of balloon angioplasty failed to result in expansion. Our case highlights that shockwave intravascular lithotripsy is a feasible, safe, and effective adjunctive therapy for treating calcified pulmonary vein stenosis.

Serious iatrogenic complications: pulmonary vein stenosis after ablation of atrial fibrillation

Pulmonary vein stenosis (PVS) has been recognized as a clinical entity complicating radiofrequency or cryoenergy ablation for atrial fibrillation. Although reduced by technical and procedural advancements, this complication portends remarkable morbidity and presents insidiously with non-specific symptoms causing frequent misdiagnosis and wrong management that lead to detection delay and major adverse implications. Non-invasive imaging is key for timely diagnosis and transcatheter procedural planning. Most recent consensus on severe and symptomatic PVS management indicates that stenting is the preferred treatment because of superior long-term patency compared to balloon angioplasty, particularly in patients with larger reference vessel diameter. However, the rate of recurrent stent restenosis is high and remains a great challenge. Goal of our manuscript is to provide a comprehensive review regarding pathophysiology, detection, treatment, and prevention of this serious iatrogenic complication.

Comprehensive review of pulmonary vein stenosis post-atrial fibrillation ablation: diagnosis, management, and prognosis

Pulmonary vein stenosis (PVS) can occasionally occur in the follow-up after pulmonary vein isolation (PVI) for atrial fibrillation (AF). During PVI, ablation is performed at the PV ostium or distal part, leading to tissue damage. This damage can result in fibrosis of the necrotic myocardium, proliferation, and thickening of the vascular intima, as well as thrombus formation, further advancing PVS. Mild-to-moderate PVS often remains asymptomatic, but severe PVS can cause symptoms, such as dyspnea, cough, fatigue, decreased exercise tolerance, chest pain, and hemoptysis. These symptoms are due to pulmonary hypertension and pulmonary infarction. Imaging evaluations such as contrast-enhanced computed tomography are essential for diagnosing PVS. Early suspicion and detection are necessary, as underdiagnosis can lead to inappropriate treatment, disease progression, and poor outcomes. The long-term prognosis of PVS remains unclear, particularly regarding the impact of mild-to-moderate PVS over time. PVS treatment focuses on symptom management, with no established definitive solutions. For severe PVS, transcatheter PV angioplasty is performed, though the risk of restenosis remains high. Restenosis and reintervention rates have improved with stent implantation compared with balloon angioplasty. The role of subsequent antiplatelet therapy remains uncertain. Dedicated evaluation is essential for accurate diagnosis and appropriate management to avoid significant long-term impacts on patient outcomes.

Incidence of pulmonary vein stenosis in two types of cryoballoon systems

Background

Currently, two types of cryoballoon (CB) systems are available for catheter ablation of atrial fibrillation (AF). Since the POLARx (Boston Scientific) is softer during freezing than the Arctic Front Advance Pro (AFA-Pro; Medtronic), it tends to go more deeply into the pulmonary vein (PV), risking PV stenosis.

Methods

Ninety-one patients underwent initial CB ablation for paroxysmal AF (AFA-Pro 56; POLARx 35). Twenty-six from each group were extracted using propensity score matching. The PV cross-sectional area (PVA) was measured by tracing the area within the PV plane at 5-mm intervals from the PV ostium in a distal direction for 20 mm or to the bifurcation in each PV. The PVA was compared before and 3 months after ablation.

Results

Time to balloon temperatures of -30 and - 40°C was significantly shorter and the nadir temperature was significantly lower with POLARx than with AFA-Pro. In the left inferior (LI) PV and right superior (RS) PV, the freezing balloon position was significantly deeper in POLARx than in AFA-pro. The freezing position in RSPV with mild to moderate narrowing was deeper than those without (10.2 ± 3.3 mm vs. 8.2 ± 1.8 mm, p = .01). In RSPV, the reduction of PVA tended to be greater with the POLARx than with the AFA-Pro (26.1% ± 14.1% vs. 19.9% ± 10.3%, p = .07).

Conclusion

There was no significant difference in the incidence of PV stenosis between POLARx and AFA-Pro. However, if POLARx goes deep into the PVs, we will still have to be careful.

Pulmonary vein narrowing after pulsed field versus thermal ablation

AIMS

When it occurs, pulmonary vein (PV) stenosis after atrial fibrillation (AF) ablation is associated with significant morbidity. Even mild-to-moderate PV narrowing may have long-term implications. Unlike thermal ablation energies, such as radiofrequency (RF) or cryothermy, pulsed field ablation (PFA) is a non-thermal modality associated with less fibrotic proliferation. Herein, we compared the effects of PFA vs. thermal ablation on PV narrowing after AF ablation.

METHODS AND RESULTS

ADVENT was a multi-centre, randomized, single-blind study comparing PFA (pentaspline catheter) with thermal ablation-force-sensing RF or cryoballoon (CB)-to treat drug-refractory paroxysmal AF. Pulmonary vein diameter and aggregate cross-sectional area were obtained by baseline and 3-month imaging. The pre-specified, formally tested, secondary safety endpoint compared a measure of PV narrowing between PFA vs. thermal groups, with superiority defined by posterior probability > 0.975. Among subjects randomized to PFA (n = 305) or thermal ablation (n = 302), 259 PFA and 255 thermal ablation (137 RF and 118 CB) subjects had complete baseline and 3-month PV imaging. No subject had significant (≥70%) PV stenosis. Change in aggregate PV cross-sectional area was less with PFA (-0.9%) than thermal ablation (-12%, posterior probability > 0.999)-primarily driven by the RF sub-cohort (-19.5%) vs. CB sub-cohort (-3.3%). Almost half of all PFA PV diameters did not decrease, but the majority (80%) of RF PVs decreased, regardless of PV anatomic location.

CONCLUSION

In this first randomized comparison of PFA vs. thermal ablation, PFA resulted in less PV narrowing-thereby underscoring the qualitatively differential and favourable impact of PFA on PV tissue.

Drug-Coated Balloon Venoplasty to Treat Iatrogenic Pulmonary Vein Stenosis

Pulmonary vein stenosis (PVS) is a condition that has seen a decrease in incidence in recent years. Whereas balloon angioplasty and stenting are both acceptable treatment options for PVS, they are limited by the high rate of restenosis. This research paper presents 4 cases of severe symptomatic PVS that were successfully treated with the use of drug-coated balloons, resulting in positive outcomes. (Level of Difficulty: Advanced.).

Catheter-Based Electroporation: A Novel Technique for Catheter Ablation of Cardiac Arrhythmias

Catheter ablation of arrhythmias is now standard of care in invasive electrophysiology. Current ablation strategies are based on the use of thermal energy. With continuous efforts to optimize thermal energy delivery, effectiveness has greatly improved; however, safety concerns persist. This review focuses on a novel ablation technology, irreversible electroporation (IRE), also known as pulsed-field ablation which may be a safer alternative for arrhythmia management. Pulsed-field ablation is thought to be a nonthermal ablation that applies short-duration high-voltage electrical fields to ablate myocardial tissue with high selectivity and durability while sparing important neighboring structures such as the esophagus and phrenic nerves. There are multiple ongoing studies investigating the potential superior outcomes of IRE compared to radiofrequency ablation in treating patients with atrial and ventricular arrhythmias. In this review, we describe the current evidence of preclinical and clinical trials that have shown promising results of catheter-based IRE.

Pathogenesis, Evaluation, and Management of Pulmonary Vein Stenosis: JACC Review Topic of the Week

Pulmonary vein stenosis (PVS) can arise from several etiologies, including congenital, acquired, and iatrogenic sources. PVS presents insidiously, leading to significant delays in diagnosis. A high index of suspicion and dedicated noninvasive evaluation are key to diagnosis. Once diagnosed, both noninvasive and invasive evaluation may afford further insights into the relative contribution of PVS to symptoms. Treatment of underlying reversible pathologies coupled with transcatheter balloon angioplasty and stenting for persistent severe stenoses are established approaches. Ongoing refinements in diagnostic modalities, interventional approaches, postintervention monitoring, and medical therapies hold promise to further improve patient outcomes.

Stiff left atrial syndrome with pulmonary veins occlusion after percutaneous radiofrequency ablation: a life-long complication that can lead to heart transplantation

BACKGROUND

Stiff left atrial syndrome (SLAS) and pulmonary vein (PV) occlusion are rare yet potentially major life-long complications after radiofrequency ablation for atrial fibrillation. While mostly controlled by medical management, SLAS can progress to refractory congestive heart failure. Treatment of PV stenosis and occlusion remains a challenging problem with ongoing risk for recurrence regardless of techniques employed. Herein we present the case of a now 51-year-old male with acquired PV occlusion and SLAS who, over the course of eleven years, despite multiple interventions, ultimately required heart transplantation.

CASE PRESENTATION

After undergoing three radiofrequency catheter procedures for paroxysmal atrial fibrillation (AF), a hybrid ablation was planned due to reappearance of symptomatic AF. Preoperative echocardiography and chest computed tomography (CT) revealed an occlusion of both left PVs. Furthermore, left atrial dysfunction, high pulmonary artery and pulmonary wedge pressures were diagnosed as well as an important reduction of the left atrial volume. The diagnosis of stiff left atrial syndrome was made. Primary surgical repair of the left-sided PVs was performed using a pericardial patch as a tubular neo-vein, combined with cryoablation in the left and right atrium to treat the patient's arrhythmia. Initial results were favorable, however, after two years the patient experienced progressive restenosis with hemoptysis. Therefore, stenting of the common left PV was performed. Over the years, progressive right heart failure with severe tricuspid regurgitation developed, despite maximal medical therapy, which led to the need for heart transplantation.

CONCLUSION

The impact of PV occlusion and SLAS after percutaneous radiofrequency ablation can be lifelong and devastating for the clinical course of the patient. Since the presence of a small left atrium could be an important predictor for SLAS in case of redo ablation, preprocedural imaging should guide the operator to an algorithm of a decision-making containing lesion set, energy source, and safety of re-ablation.

A rare case of right heart failure with the necessity for veno-arterial extracorporeal membrane oxygenation following pulmonary vein stenosis after radiofrequency ablation for atrial fibrillation

Pulmonary vein stenosis (PVS) after radiofrequency energy-mediated percutaneous pulmonary vein isolation as a treatment option for atrial fibrillation is a serious complication and the prevalence in historical reports varies between 0% and 42%. Symptoms of PVS are nonspecific and can include general symptoms such as dyspnea, cough, recurrent pneumonia, and chest pain. Pathophysiologically it increases the postcapillary pressure in the pulmonary circuit and may result in pulmonary hypertension (PH). Misdiagnosis and delayed treatment are common. We here report a case of a 59-year-old female with a history of pulmonary vein ablation followed by progressive dyspnea (New York Heart Association IV), right heart failure, CPR, and the need for extracorporeal membrane oxygenation (ECMO). Further treatment strategy includes pulmonary vein dilatation and stenting of both the left superior pulmonary vein and left inferior pulmonary vein, as well as balloon dilatation of RIPV under temporary ECMO support. Symptomatic, severe PVS is a rare complication after catheter ablation of atrial fibrillation. PVS can result in life-threatening complications such as PH with acute right heart failure. Early diagnosis is crucial but challenging. Mechanical cardiopulmonary support by veno-arterial ECMO for bridging to angioplasty could be a lifesaving option.

Pulmonary Vein Angioplasty for Pulmonary Vein Stenosis After Ablation Therapy for Atrial Fibrillation - A Report of 7 Cases

BACKGROUND

Pulmonary vein (PV) stenosis after atrial fibrillation (AF) ablation is rare; however, it remains a serious complication. PV angioplasty is reportedly an effective therapy; however, a dedicated device for PV angioplasty has not been developed, and the detailed procedural methods remain undetermined. This study describes the symptoms, indications, treatment strategies, and long-term outcomes for PV stenosis after AF ablation.

METHODS AND RESULTS

This study retrospectively analyzed 7 patients with PV stenosis after catheter ablation for AF and who had undergone PV angioplasty at our hospital during 2015-2021. PV stenosis occurred in the left superior (5 patients) and left inferior (2 patients) PV. Six patients had hemoptysis, chest pain, and dyspnea. Seven de novo lesions were treated using balloon angioplasty (BA) (3 patients), a bare metal stent (BMS) (3 patients), and a drug-coated balloon (DCB) (1 patient). The restenosis rate was 42.9% (n=3; 2 patients in the BA group and 1 patient in the DCB group). The repeat treatment rate was 28.6% (2 patients in the BA group). Stenting was performed as repeat treatment. One patient with subsequent repeat restenosis development underwent BA. Ten PV angioplasties were performed; there were no major complications.

CONCLUSIONS

Regarding PV angioplasty after ablation therapy for AF, stenting showed superior long-term PV patency than BA alone; therefore, it should be considered as a standard first-line approach.

Pulmonary vein reconstruction for pulmonary vein stenosis and occlusion after surgical ablation

Acquired pulmonary vein (PV) stenosis (PVS) is a complication following cardiac catheter intervention. However, very few cases of PVS after surgical ablation have been reported. We herein report a case of stenosis and occlusion at the left atrium to each pulmonary vein after surgical ablation. A 73-year-old woman who had received aortic valve replacement and pulmonary vein isolation 10 months earlier was diagnosed with congestive heart failure accompanied by pulmonary hypertension. Contrast-enhanced computed tomography revealed stenosis and complete occlusion of the left atrium to all four pulmonary veins. Surgical repair was performed via pericardial patch reconstruction of the left atrium to each PV. Treating multiple PV lesions with involvement of the left atrium wall requires tailored methods. However, there have been few reports concerning such methods of reconstruction. We herein report a method of reconstructing the left atrium and pulmonary veins at the same time.

The Blinding Period Following Ablation Therapy for Atrial Fibrillation: Proarrhythmic and Antiarrhythmic Pathophysiological Mechanisms

Atrial fibrillation (AF) causes heart failure, ischemic strokes, and poor quality of life. The number of patients with AF is estimated to increase to 18 million in Europe in 2050. Pharmacological therapy does not cure AF in all patients. Ablative pulmonary vein isolation is recommended for patients with drug-resistant symptomatic paroxysmal AF but is successful in only about 60%. In patients in whom ablative therapy is successful on the long term, recurrence of AF may occur in the first weeks to months after pulmonary vein ablation. The early recurrence (or delayed cure) of AF is not understood but forms the basis for the generally accepted 3-month blinding (or blanking) period after ablation therapy, which is not included in the evaluation of the eventual success rate of the procedures. The underlying pathophysiological processes responsible for early recurrence and the delayed cure are unknown. The implicit assumption of the blinding period is that the AF mechanism in this period is different from the ablation-targeted AF mechanism (ectopy from the pulmonary veins). In this review, we evaluate the temporary and long-lasting pro- and antiarrhythmic effects of each of the pathophysiological processes and interventions (necrosis, ischemia, oxidative stress, edema, inflammation, autonomic nervous activity, tissue repair, mechanical remodeling, and use of antiarrhythmic drugs) occurring in the blinding period that can modulate AF mechanisms. We propose that stretch-reducing ablation scar is a permanent antiarrhythmic mechanism that develops during the blinding period and is the reason for delayed cure.

Pulmonary vein stenosis after HotBalloon pulmonary vein isolation of paroxysmal atrial fibrillation

HotBalloon-based pulmonary vein isolation (HBPVI) has yielded encouraging clinical results in the treatment of paroxysmal atrial fibrillation (PAF). However, pulmonary vein (PV) stenosis remains a concern. The influence of longer application duration on PV stenosis has not yet been systematically evaluated. All patients who underwent first HBPVI of PAF with pre- and post-ablation computed tomography (CT) were included. We used single-shot technique with application duration of 180 s in the RSPV, 180-240 s in the LSPV, and 120 s in the lower PV procedures. PV stenosis was analyzed using CT and categorized as moderate (50-70%), and severe (> 70%) reduction in PV diameter. We analyzed imaging of the PV anatomy before ablation and during follow-up in 84 patients. Among them, 7 (8.3%) showed moderate stenosis, and 3 (3.6%) had severe stenosis including one total occlusion patient. All severe stenosis and total occlusion occurred in RSPV and LSPV procedures with longer application duration. No severe stenosis nor total PV occlusion occurred in inferior PV procedures with shorter application duration. The incidence of PV stenosis ≥ 50% or total PV occlusion was significantly lower in inferior PV than RSPV and LSPV procedures (0.6%, 6.0%, 8.0%, p = 0.01, respectively). All cases of PV stenosis including total PV occlusion patients were asymptomatic. No intervention for PV stenosis was performed. The risk of PV stenosis in HBPVI was rare in lower PV procedure with shorter application duration. An application duration setting of 120 s in lower PV procedure might be effective to prevent PV stenosis.

Experience using drug-coated balloon venoplasty for acquired pulmonary vein stenosis after radiofrequency ablation

Pulmonary vein stenosis is a rare but severe complication of catheter ablation for arterial fibrillation (AF). Symptoms include dyspnea, hemoptysis, recurrent pneumonia, and pulmonary hypertension. We herein discuss a 27-year-old male patient who presented with hemoptysis and dyspnea three months after catheter ablation for AF. Computed tomography demonstrated an occluded left inferior pulmonary vein (LIPV) and left lower lung edema secondary to severe stenosis of the LIPV. The patient underwent treatment, including drug-coated balloon (DCB) venoplasty. Treatment of pulmonary vein stenosis involving percutaneous interventions with balloon angioplasty and stenting carry a high risk of restenosis. DCB therapy may be used to prevent stenosis. <Learning objective: The use of a drug-coated balloon is feasible and may provide good long-term outcomes in acquired pulmonary vein stenosis after radiofrequency ablation.>.

Anatomical changes in the pulmonary veins and left atrium after cryoballoon ablation

BACKGROUND

The anatomical changes in pulmonary veins (PVs) after cryoballoon ablation (CBA) are unclear. We aimed to determine the morphological changes in the PVs and left atrium (LA) along with the predictive factors for clinical PV stenosis.

METHODS

We analyzed data of 320 PVs from 80 patients who underwent CBA for atrial fibrillation (age: 62 ± 10 years, 59 males). All patients underwent pre- and post-procedural cardiac computed tomography. We defined clinical PV stenosis when the cross-sectional area decreased by more than 50%.

RESULTS

The average ostial PV area and LA volume decreased significantly after CBA (pre- vs post-CBA; 2.4 ± 1.0 cm² vs 2.3±1.1 cm² , P < .001, 75.0 ± 23.2 cm³ vs 70.7 ± 21.9 cm³ , P < .001, respectively). There was a significant correlation between the reduction rates of the PV area and those of LA volume (R = 0.411, P < .001). The larger preoperative PV area and greater reduction in LA volume were associated with advanced PV narrowing. Clinical PV stenosis was observed in six PVs, was more common in females (male vs female; 0.8% vs 4.8%, P = .043), and tended to be more frequent in left PVs (left PVs vs right PVs; 3.1% vs 0.6%: P = .107), irrespective of the LA volume reduction.

CONCLUSIONS

The significant reduction of the ostial PV area occurred after CBA, which correlated with the reduction rate of LA volume. The narrowing of the PV was partly produced by the LA volume reduction. Clinical PV stenosis was more common in females and tended to be more frequent in left PVs.

Treatment of Congenital and Acquired Pulmonary Vein Stenosis

PURPOSE OF REVIEW

Pulmonary vein stenosis (PVS) is a rare entity that until the last 2 decades was seen primarily in infants and children. Percutaneous and surgical interventions have limited success due to relentless restenosis, and mortality remains high. In adults, acquired PVS following ablation for atrial fibrillation has emerged as a new syndrome. This work will review these two entities with emphasis on current treatment.

RECENT FINDINGS

Greater emphasis on understanding and addressing the mechanism of restenosis for congenital PVS has led to the use of drug-eluting stents (DES) and systemic drug therapy to target neo-intimal growth. Frequent reinterventions are positively affecting outcomes. Longer-term outcomes of percutaneous treatment for acquired PVS are emerging. Treatment of congenital PVS continues to be plagued by restenosis. DES show promise, but frequent reinterventions are required. Larger upstream vein diameter predicts success for congenital and acquired PVS interventions. Efforts to induce/maintain vessel growth are important for future treatment strategies.

Radiofrequency Catheter Ablation: How to Manage and Prevent Collateral Damage?

Radiofrequency catheter ablation has become the standard of care for the management of various arrhythmias and, in fact, the first-line therapy for many tachyarrhythmias. It entails creating scar tissue in the heart in regions where abnormal impulses form or propagate to restore normal cardiac conduction. As the heart is a complex organ and is surrounded by and related to many other anatomical structures, it is important to avoid the collateral damage that can happen from radiofrequency (RF) ablation on the endocardium as well as on the epicardium. This review explores methods for mitigating or limiting collateral damage during catheter ablation.

Alcohol-Mediated Renal Sympathetic Neurolysis for the Treatment of Hypertension: The Peregrine™ Infusion Catheter

Renal sympathetic denervation using conventional non-irrigated radiofrequency catheters has potential technical shortcomings, including limited penetration depth and incomplete circumferential nerve damage, potentially impacting therapeutic efficacy. Against this background, second generation multi-electrode, radiofrequency and ultrasound renal denervation systems have been developed to provide more consistent circumferential nerve ablation. Irrigated catheters may allow deeper penetration while minimizing arterial injury. In this context, catheter-based chemical denervation, with selective infusion of alcohol, a potent neurolytic agent, into the perivascular space, may minimize endothelial, intimal and medial injury while providing circumferential neurolysis. Animal studies demonstrate pronounced renal norepinephrine level reductions and consistent renal nerve injury after perivascular alcohol infusion using the Peregrine Catheter. Early clinical studies demonstrated significant blood pressure reductions and a reasonable safety profile. Randomized sham-controlled trials (NCT03503773, NCT02910414) are underway to examine whether the aforementioned theoretical advantages of alcohol-medicated denervation with the Peregrine System™ Kit translate into clinical benefits.

A Unique Compensatory Mechanism for Total Pulmonary Vein Occlusion Post Atrial Fibrillation Catheter Ablation Visualized by Multimodality Imaging

Pulmonary vein (PV) stenosis is a rare and serious complication of radiofrequency catheter ablation (RFCA) for atrial fibrillation. However, it can be asymptomatic or mildly symptomatic depending on the severity of the stenosis and the development of compensatory mechanisms. This study provides a detailed description and visualization of a unique type of venous collaterals that bypass the PV stenosis and drain directly in the left atrium alleviating PV stenosis sequelae. This study reports a case of a 61-year-old male who presented with mild dyspnea and fatigue 3 years post atrial fibrillation RFCA. After a thorough evaluation of the case, a redo-ablation was planned. As a part of the preablation workup, a transesophageal echocardiography (TEE), a ventilation-perfusion (V/Q) scan of the lungs, and a chest computed tomography angiogram (CTA) were performed. The TEE revealed total obstruction of the left superior PV, with no color Doppler flow detected. It also showed evidence of multiple collateral flows at the os of the left superior PV. The V/Q scan showed a large perfusion defect involving the entire left upper lobe consistent with a compromised left upper PV flow. The CTA with 3D volume rendering revealed the total occlusion of the left superior PV at its ostium. Moreover, the scan confirmed the pulmonary venous drainage via small collateral channels that was suggested by the TEE.

Direct Current Ablation of Deep Substrate Arrhythmia

Direct-current ablation has been reinvestigated in animal models with considerably good outcomes and safety margins. Its modified version using biphasic energy lowers the current density further, minimizing its complications. We report a first-in-human ablation of ventricular tachycardia using biphasic direct current with short-term success and no procedural complications. (Level of Difficulty: Intermediate.)

Long-term outcome of percutaneous intervention for pulmonary vein stenosis after pulmonary vein isolation procedure

OBJECTIVES

Report long-term outcomes of percutaneous intervention in patients with pulmonary vein stenosis (PVS) after pulmonary vein isolation (PVI) from a single center over 16 years.

BACKGROUND

Outcome reports of percutaneous intervention for PVS resulting from PVI are limited.

METHODS

Retrospective review of all patients with PVS after PVI who underwent percutaneous intervention at the Cleveland Clinic Foundation between January 2000 and December 2016.

RESULTS

A total of 205 patients underwent cardiac catheterization for PVS during the study period. Completely occluded veins which could not be recanalized occurred in six patients. Of the remaining 199 patients, 27 (14%) were lost to follow-up, leaving 172 patients with 276 veins for analysis. Balloon angioplasty was performed in 62 veins and stent implantation in 250 (primary in 214, to treat postdilation restenosis in 36). Re-intervention occurred in 45/62 (73%) balloon-dilated veins and 45/250 (18%) stented veins. Freedom from re-intervention at 1 and 5 years was 90 and 73% following stenting versus 40 and 23% following balloon dilation (p < .001, Hazard ratio (HR) = 5.7). Veins with stent diameter ≥7 mm (n = 231) had greater freedom from re-intervention (95% at 1 year, 79% at 5 years) than veins with stents <7 mm (43% at 1 year, 9% at 5 years), p < .001. There was clear symptomatic improvement after intervention and no procedural mortality.

CONCLUSIONS

Stent implantation at ≥7 mm for PVS after PVI is associated with low rates of re-intervention, in contrast to balloon dilation and stenting with small conventional stents.

Acquired Pulmonary Vein Stenosis After Radiofrequency Ablation for Atrial Fibrillation: Single-Center Experience in Catheter Interventional Treatment

OBJECTIVES

The aim of the present study was to analyze and report a single-center experience with catheter interventional treatment of radiofrequency-induced pulmonary vein stenosis (PVS) following atrial fibrillation (AF) ablation.

BACKGROUND

Catheter interventional treatment of radiofrequency-induced PVS following AF ablation remains a challenging field because of a lack of randomized data and treatment guidelines.

METHODS

All patients at a single center who underwent catheter interventional treatment for radiofrequency-induced PVS were retrospectively assessed.

RESULTS

From January 2004 to September 2017, the total rate of PVS following interventional AF ablation was 0.78% (87 of 11,103). Thirty-nine patients with PVS were treated with 84 catheter interventions: 68 (81%) with percutaneous transluminal balloon angioplasty (PTA) and 16 (19%) with stent implantation. The distribution of stent type was 3 drug-eluting stents (19%) and 13 bare-metal stents (81%). The overall restenosis rate was 53% after PTA versus 19% after stent implantation (p = 0.007) after a median follow-up period of 6 months (interquartile range: 3 to 55 months). The total complication rate for PTA was 10% versus 13% for stenting (p = NS).

CONCLUSIONS

This study demonstrates significantly better outcomes in terms of restenosis after stent implantation versus PTA only, with comparable complication rates for these 2 options of interventional treatment of radiofrequency-induced PVS. In summary, despite the lack of randomized studies, the present data and currently available published studies seem to favor stent implantation as a first-line therapy in patients with radiofrequency-induced severe PVS.

Clinical characteristics of patients with atrial fibrillation suffering from pulmonary vein stenosis after radiofrequency ablation

OBJECTIVE

Pulmonary vein stenosis (PVS) is a serious complication in patients with atrial fibrillation (AF) receiving radiofrequency catheter ablation (RFCA). We therefore examined these patients' clinical characteristics in relation to PVS occurrence.

METHOD

We retrospectively analyzed the clinical symptoms, diagnostic procedures, and treatment strategies in patients with AF who developed PVS after RFCA.

RESULTS

Among 205 patients with AF who underwent RFCA, five (2.44%) developed PVS (all men; age 44-64 years; AF history 12-60 months; 2 paroxysmal AF, 3 persistent AF). One patient underwent two RFCA sessions and the others received one. The time to PVS diagnosed by pulmonary vein computed tomography angiography (CTA) was 3 to 21 months. PVS symptoms included dyspnea and hemoptysis. Nine pulmonary veins developed PVS. Single mild PVS occurred in two asymptomatic patients and multiple PVS or single severe PVS in three symptomatic patients who underwent pulmonary vein angiography and stent placement. Symptoms in the three patients significantly improved after stent implantation; however, stent restenosis occurred 1 year later in one case.

CONCLUSION

PVS is a rare complication of RFCA for AF that can be diagnosed by CTA. Pulmonary vein stent implantation can remarkably improve the symptoms, but stent restenosis may occur.

Natural course of acquired pulmonary vein stenosis after radiofrequency ablation for atrial fibrillation-Is routine follow-up imaging indicated or not?

INTRODUCTION

Thermal injury during radiofrequency ablation (RFA) of atrial fibrillation (AF) can lead to pulmonary vein stenosis (PVS). The aim of the present study was to analyze the natural course of RFA-induced PVS with regard to the grade of stenosis, clinical symptoms, and mortality during long-term follow-up.

METHODS AND RESULTS

All patients with follow-up imaging for radiofrequency-induced untreated PVS were retrospectively assessed. From 2004 to 2017, the total rate of PVS following AF ablation in our center was 0.78% (87 of 11 103). Thirty-eight patients with a total of 54 untreated PVS underwent follow-up including imaging scan. The mean degree of stenosis at the time of diagnosis was 57% ± 27% vs 45% ± 35% (P = .05) after a mean follow-up of 43 ± 31 months. There was a shift in severity of the PVS: 18 of 54 (33%) vs 16 of 54 (30%) severe PVS, 19 of 54 (35%) vs 10 of 54 (18%) moderate PVS, and 17 of 54 (32%) vs 28 of 54 (52%) mild PVS (P = .0001). The mean symptom score decreased significantly during follow-up (1.8 ± 1.0 vs 0.4 ± 0.5, P = .0001). Each of the four patients with progression of PVS underwent another pulmonary vein isolation for AF recurrence following pulmonary vein reconduction during follow-up period.

CONCLUSION

This study showed a spontaneous reduction in stenosis grade and symptoms of PVS over a 3.5-year follow-up. Consequently, routine follow-up imaging of PVS seems not to be necessary. However, additional RF energy delivery to stenotic pulmonary veins should be avoided if possible. In case of conduction recovery, the ablation line should be done wide-antrally and follow-up imaging of PVS is recommended.

Pathology Approaches to Determine Safety and Efficacy of Cardiac Ablation Catheters

Cardiac electrophysiology utilizes nonimplantable, catheter-based devices for diagnosis and treatment of arrhythmias as well as electroanatomical mapping of cardiac chambers. Gross pathology and histopathological assessments in preclinical studies play critical roles in determining the safety and efficacy of cardiac ablation systems used to treat tachyarrhythmias. The pathologist must assess ablation sites, adjacent structures and organs, and downstream organs to characterize the effects of the ablation treatment and determine whether adverse local reactions, collateral injury, or downstream thromboembolism are present. Histopathological assessment serves as an adjunct to electroanatomical data in determining efficacy in preclinical studies. Histopathology is the standard in definitively demonstrating transmurality of ablation lesions, which is necessary for complete conduction block, as well as showing the linear or circumferential distribution of a contiguous, transmural ablation lesion necessary for electroanatomical isolation of entire target structures such as pulmonary veins and the cavotricuspid isthmus, which are involved in propagating certain arrhythmias. This article will detail gross and histological methods for the pathology assessment of preclinical studies evaluating the safety and/or efficacy of cardiac ablation catheter systems as well as discuss correlation of pathology data with other supporting evidence for safety and efficacy such as acute, electroanatomical data.

Mechanisms of Intravascular Linear Ablation Induced Restenosis in Rabbit Abdominal Aorta

OBJECTIVES

Percutaneous coronary intervention (PCI) is the mainstay treatment for coronary artery disease but complications such as in-stent restenosis and thrombosis remain problematic. Radiofrequency balloon angioplasty (RBA) can improve lumen dimension, fusing intimal tears, and artery dissection but is associated with higher restenosis rate.

METHODS

After establishing an atherosclerosis model based on endothelial abrasion and high cholesterol diet, forty-five rabbits were randomly divided into three groups: RBA (n=20), percutaneous transluminal angioplasty (PTA) (n=20), and control groups (n=5). The RBA and PTA groups were subdivided according to harvested time posttreatment, respectively (1 hour, 7 days, 14 days, and 28 days). Aorta segments were then isolated for hematoxylin and eosin staining, Masson trichrome staining, immunohistochemistry, and Western blot for TLR-4, NF-κB, MCP-1, and VCAM-1expression.

RESULTS

At 28 days, intimal area was significantly lower in the RBA group compared to the PTA and control groups, whilst luminal and medial area were comparable in the RBA and PTA group but higher and lower than the control group, respectively. Expression of TLR-4, NF-κB, MCP-1, and VCAM-1 showed no significant difference between RBA and PTA groups.

CONCLUSIONS

RBA can depress the intimal hyperplasia and promote dilatation of the artery to greater extents than PTA at 28 days. However, this did not involve TLR-4 signaling pathway, which likely plays a negligible role in mediating restenosis. Reduction of intimal hyperplasia may be due to injury of ablation to the tunica media and inhibition of VSMC proliferation and migration.

Serial changes in vessel walls of renal arteries after catheter-based renal artery denervation: insights from volumetric computed tomography analysis

Aim

Radiofrequency ablation of peri-arterial renal autonomic nerves has been studied as a potential therapeutic option for resistant hypertension. While recent clinical trials have reported its efficacy, there is paucity of data addressing the effects of the procedure on renal arteries, such as changes in vessel and lumen areas. Herein, the effect of atheroma burden on renal arteries after renal denervation was assessed using computed tomography (CT) imaging.

Materials and methods

Serial renal artery CT imaging was conducted in 38 patients from the EnligHTN™ I study, a prospective, multicenter study evaluating the efficacy of the EnligHTN multi-electrode radiofrequency ablation catheter in resistant hypertensive subjects. Cross-sectional images of renal arteries at 1 mm intervals were acquired using commercially available software (3mensio Structural Heart version 5.1). Vessel and lumen areas were manually traced in each image. Vessel wall volume (VWV) and percent vessel wall volume (P-VWV) were calculated. The measurements within the ablation (first 30 mm segments) and the non-ablation (subsequent 30 mm segment after the first bifurcation of renal arteries) zones were compared.

Results

On serial evaluation, greater increase in P-VWV and VWV was observed in the ablation zone (change in P-VWV, 6.7%±5.1% vs 3.6%±2.8%, P=0.001; change in VWV, 106.3±87.4 vs 23.0±18.2 mm³, P=0.001). Receiver-operating characteristic analysis demonstrated baseline P-VWV in the ablation zone >37.1% as an optimal cutoff value to predict its substantial progression after the procedure (area under the curve=0.88, sensitivity 89.8%, specificity 79.1%).

Conclusion

Change in vessel wall was greater within the segments receiving renal artery denervation. Baseline VWV predicted its substantial increase after the procedure. These observations suggest that atheroma burden within the renal arteries is a potential contributing factor to vascular changes after renal sympathetic denervation.

Usefulness of multidetector computed tomography before and after pulmonary vein isolation

OBJECTIVE

To analyze the usefulness of multidetector computed tomography (MDCT) in the preprocedural evaluation and follow-up of patients undergoing radiofrequency ablation of pulmonary veins and the impact of the MDCT findings on the approach to treatment.

METHOD

We retrospectively analyzed 92 consecutive MDCT studies done in 80 patients between January 2011 and June 2013; 70 (76%) studies were done before a first ablation procedure and 22 (24%) were done in patients who had undergone an ablation procedure.

RESULTS

Findings were useful in 34% of the patients who underwent MDCT before the first ablation procedure and in 68% of the studies done after a procedure. The incidence of stroke associated with the ablation procedure was 3%, similar to the incidence recorded in our center before we started to use MDCT to evaluate the anatomy of the left atrium. All symptomatic patients had some pulmonary vein stenosis, and 80% had significant stenosis. Furthermore, the stenoses progressed very rapidly; treatment with balloon angioplasty was associated with early restenosis. Stenting was an alternative in cases of failed angioplasty.

CONCLUSION

In the preprocedural evaluation and postprocedural follow-up of patients undergoing pulmonary vein isolation, MDCT is useful for guiding treatment and detecting complications.

Surgical Ablation of Atrial Fibrillation Using Energy Sources

Surgical ablation, concomitant with other operations, is an option for treatment in patients with chronic atrial fibrillation. The aim of this study is to present a literature review on surgical ablation of atrial fibrillation in patients undergoing cardiac surgery, considering energy sources and return to sinus rhythm. A comprehensive survey was performed in the literature on surgical ablation of atrial fibrillation considering energy sources, sample size, study type, outcome (early and late), and return to sinus rhythm. Analyzing studies with immediate results (n=5), the percentage of return to sinus rhythm ranged from 73% to 96%, while those with long-term results (n=20) (from 12 months on) ranged from 62% to 97.7%. In both of them, there was subsequent clinical improvement of patients who underwent ablation, regardless of the energy source used. Surgical ablation of atrial fibrillation is essential for the treatment of this arrhythmia. With current technology, it may be minimally invasive, making it mandatory to perform a procedure in an attempt to revert to sinus rhythm in patients requiring heart surgery.

Direct Pulmonary Vein Ablation With Stenosis Prevention Therapy

INTRODUCTION

The dominant location of electrical triggers for initiating atrial fibrillation (AF) originates from the muscle sleeves inside pulmonary veins (PVs). Currently, radiofrequency ablation (RFA) is performed outside of the PVs to isolate, rather than directly ablate these tissues, due to the risk of intraluminal PV stenosis.

METHODS

In 4 chronic canine experiments, we performed direct PV muscle sleeve RFA ± postablation drug-coated balloon (DCB) treatment with paclitaxel/everolimus. Of the 4 PVs, 2 PVs were ablated and treated with DCB, 1 PV was ablated without DCB treatment (positive control), and 1 PV was left as a negative control. Local electrograms were assessed in PVs for near-field signals and were targeted for ablation. After 12-14 weeks survival, PVs were interrogated for absence of near-field PV potentials, and each PV was assessed for stenosis.

RESULTS

All canines survived the study period without cardiorespiratory complications, and remained ambulatory. In all canines, PVs that were ablated and treated with DCB remained without any significant intraluminal stenosis. In contrast, PVs that were ablated and not treated with DCB showed near or complete intraluminal stenosis. At terminal study, PV potentials remained undetectable. A blinded, histologic analysis demonstrated that ablated PVs without DCB treatment had extensive thrombus, fibrin, mineralization, and elastin disruption.

CONCLUSION

Our chronic canine data suggest that direct PV tissue ablation without subsequent stenosis is feasible with the use of postablation DCBs.