S. Riva

Left Mitral Isthmus Ablation Associated with PV Isolation: Long-Term Results of a Prospective Randomized Study

Background: The deployment of an ablation line connecting the left inferior PV to the mitral annulus (mitral isthmus line [MIL]) enhances the efficacy of pulmonary vein disconnection (PVD) in preventing atrial fibrillation (AF) recurrences.

Electrophysiological characteristics and outcome in patients with idiopathic right ventricular arrhythmia compared with arrhythmogenic right ventricular dysplasia

Background: Idiopathic right ventricular arrhythmias (IRVA) are responsive to medical and ablative treatment and have a benign prognosis. Arrhythmias caused by right ventricular dysplasia (ARVD) are refractory to treatment and may cause sudden death. It is difficult to distinguish between these two types of arrhythmia. Objective: To differentiate patients with IRVA and ARVD by a conventional electrophysiological study. Methods: 56 patients with a right ventricular arrhythmia were studied. They had no history or signs of any cardiac disease other than right ventricular dysplasia. They were classified as having IRVA (n = 41) or ARVD (n = 15) on the basis of family history, ECG characteristics, and various imaging techniques. They were further investigated by standard diagnostic electrophysiology. Results: The two groups were clearly distinguished by the electrophysiological study in the following ways: inducibility of ventricular tachycardia by programmed electrical stimulation with ventricular extrastimuli (IRVA 3% v ARVD 93%, p < 0.0001); presence of more than one ECG morphology during tachycardia (IRVA 0% v ARVD 73%, p < 0.0001); and fragmented diastolic potentials during ventricular arrhythmia (IRVA 0% v ARVD 93%, p < 0.0001). Data from the clinical follow up in these patients supported the diagnosis derived from the electrophysiological study. Conclusions: Patients with IRVA or ARVD can be distinguished by specific electrophysiological criteria. A diagnosis of ARVD can be made reliably on the basis of clinical presentation, imaging techniques, and an electrophysiological study.

Percutaneous cardiopulmonary support for catheter ablation of unstable ventricular arrhythmias in high-risk patients.

Background and Purpose:In patients with severe cardiomyopathy, recurrent episodes of nontolerated ventricular tachycardia (VT) or electrical storm (ES) frequently cause acute heart failure and cardiac death; the suppression of the arrhythmia is therefore lifesaving, but feasibility of catheter ablation (CA) is precluded by the adverse hemodynamic conditions together with the characteristics of the arrhythmia that interdicts efficacious mapping. The use of the percutaneous cardiopulmonary support (CPS) for circulatory assistance may allow patient’s stabilization and enhance efficacy and safety of CA in this emergency setting.Patients and Methods:19 patients (19 males; mean age 61 ± 6 years; chronic ischemic cardiomyopathy, eleven patients; primary dilated cardiomyopathy, six patients; arrhythmogenic right ventricular dysplasia/ cardiomyopathy, two patients) with recurrent nontolerated VT episodes undergoing CPS-assisted CA were retrospectively evaluated. Twelve patients had acute hemodynamic failure refractory to inotropic agents and ventilatory assistance, seven patients had undergone a failing nonconventional CA procedure. 14 patients presented with ES, and in twelve the procedure was undertaken under emergency conditions within 24 h from admission. Patients were ventilated under general anesthesia and assisted by a multidisciplinary team. The CPS system consisted in a Medtronic Bio-Medicus centrifugal pump and in a Maxima Plus oxygenator, a 15-F arterial cannula, and a 17-F venous cannula.Results:Flows between 2 and 3 l/min were activated after induction of 56/62 forms of nontolerated VT, achieving hemodynamic stabilization in all patients. CA was mainly guided by conventional activation mapping and was effective in abolishing 45/56 supported VTs; in 10/19 patients all clinical VTs were suppressed by CA. Mean procedural time was 4 h and 20 min. Complete stabilization was achieved in 13 patients (68%) without VT recurrence during a 7-day in-hospital monitoring. A significant clinical improvement was observed in two patients (11%); one patient (5%) with persistent VT episodes acutely died after heart transplant. At a mean follow-up of 42 months (range 15–60 months), 5/18 patients (28%) were free from VT recurrence, 7/18 (39%) had a clear clinical improvement with reduced implantable cardioverter defibrillator interventions. 5/14 patients (36%) had ES recurrence; among them, three died because of acute heart failure. No serious CPS-related complications were observed.Conclusion:The CPS warrants acceptable hemodynamic stabilization and efficacious mapping in highrisk patients undergoing CA for unstable VT in the emergency setting. Safety and efficacy of this technique translate into significant clinical improvement in the majority of patients. Even if only relatively invasive, CPS should be reserved to patients with ES or intractable arrhythmia causing acute heart failure; moreover, the need for an experienced team of multidisciplinary operators implies that its use is restricted to selected high-competency institutions.ZusammenfassungHintergrund und Fragestellung:Bei Patienten mit schwerer Kardiomyopathie verursachen rezidivierende Episoden nicht tolerierter ventrikulärer Tachykardie (VT) oder eines elektrischen Sturms (ES) häufig akutes Herzversagen und plötzlichen Herztod; die Suppression der Arrhythmie ist daher lebensrettend, jedoch stehen der Durchführbarkeit der Katheterablation (KA) ungünstige hämodynamische Verhältnisse sowie die Charakteristika der Arrhythmie, die ein effizientes Mapping verhindert, entgegen. Der Einsatz des perkutanen kardiopulmonalen Supports (KPS) zur Kreislaufunterstützung kann zur Stabilisierung des Patienten beitragen und die Effizienz und Sicherheit der KA in diesem Notfallszenario erhöhen.Patienten und Methodik:19 Patienten (19 Männer; Durchschnittsalter 61 ± 6 Jahre; chronische ischämische Kardiomyopathie, elf Patienten; primäre dilatative Kardiomyopathie, sechs Patienten; arrhythmogene rechtsventrikuläre Dysplasie/Kardiomyopathie, zwei Patienten) mit rezidivierenden nicht tolerierten VT-Episoden, die einer KPS-unterstützten KA unterzogen wurden, wurden retrospektiv evaluiert. Zwölf Patienten hatten ein akutes, gegenüber inotropen Agenzien und assistierter Beatmung refraktäres hämodynamisches Versagen. Sieben Patienten hatten sich einem frustranen nichtkonventionellen KA-Verfahren unterzogen. 14 Patienten hatten ES, und bei zwölf wurde das Verfahren innerhalb von 24 h nach der Aufnahme unter Notfallbedingungen durchgeführt. Die Patienten wurden unter Vollnarkose beatmet und von einem multidisziplinären Team unterstützt. Das KPS-System bestand aus einer Medtronic-Bio-Medicus-Zentrifugalpumpe und einem Maxima-Plus-Oxygenator, einer arteriellen Kanüle (15 F) und einer venösen Kanüle (17 F).Ergebnisse:Nach der Induktion von 56/62 Formen nicht tolerierter VT wurden Flussraten zwischen 2 und 3 l/min eingestellt, so dass bei allen Patienten eine hämodynamische Stabilisierung erreicht wurde. Die KA wurde hauptsächlich durch konventionelles Aktivierungsmapping geführt, und sie war effizient bei der Beseitigung von 45/56 VT mit KPS; bei 10/19 Patienten wurden alle klinischen VT durch KA supprimiert. Die mittlere Eingriffszeit betrug 4 h und 20 min. Bei 13 Patienten (68%) wurde eine völlige Stabilisierung ohne rezidivierende VT während einer 7-tägigen stationären Überwachung erreicht. Bei zwei Patienten (11%) wurde eine erhebliche klinische Verbesserung beobachtet; ein Patient (5%) mit persistierenden VT-Episoden verstarb akut nach einer Herztransplantation. Nach einem mittleren Beobachtungszeitraum von 42 Monaten (Range 15–60 Monate) waren 5/18 Patienten (28%) in Bezug auf die VT rezidivfrei und 7/18 (39%) zeigten eine deutliche klinische Verbesserung mit weniger ICD-Interventionen (implantierbarer Kardioverter-Defibrillator). 5/14 Patienten (36%) hatten ES-Rezidive; davon starben drei aufgrund von akutem Herzversagen. Es wurden keine schweren, mit dem KPS im Zusammenhang stehenden Komplikationen beobachtet.Schlussfolgerung:Der KPS garantiert eine akzeptable hämodynamische Stabilisierung und effizientes Mapping bei Hochrisikopatienten, die sich notfallmäßig aufgrund einer instabilen VT einer KA unterziehen. Die Sicherheit und Effizienz dieser Technik führen bei der Mehrheit der Patienten zu einer erheblichen klinischen Verbesserung. Selbst wenn der KPS nur relativ invasiv ist, sollte er beschränkt sein auf Patienten mit ES oder hartnäckiger Arrhythmie, die akutes Herzversagen verursacht. Ferner impliziert die Notwendigkeit eines erfahrenen multidisziplinären Teams einen limitierten Einsatz in ausgewählten Einrichtungen mit hoher Fachkompetenz.

Radiofrequency ablation of atrioventricular junction and pacemaker implantation versus modulation of atrioventricular conduction in drug refractory atrial fibrillation

Modulation of atrioventricular (AV) node conduction and radiofrequency ablation of AV junction are alternative approaches to control ventricular rate in drug refractory atrial fibrillation (AF). In 2 centers, 120 patients were treated either with AV junction ablation (center 1, group 1, 60 patients [30 men, aged 64 +/- 11 years], paroxysmal AF in 24 patients) or with modulation (group 2, 60 patients [32 men, aged 58 +/- 12 years], paroxysmal AF in 43 patients). In group 1, complete AV block was achieved in all patients. In group 2, the procedure was performed in sinus rhythm (30 patients), prolonging the Wenckebach cycle length from 328 +/- 85 to 466 +/- 80 ms (p <0.01) or during AF (30 patients), decreasing ventricular rate from 178 +/- 35 to 96 +/- 35 beats/min (p <0.01), and to <100 beats/min in 17 patients (61%). Complete AV block was induced in 9 of 60 patients (15%). In groups 1 and 2, at a follow-up of 27 +/- 7 and 26 +/- 6 months, there were 2 deaths (1 cardiac, 1 sudden death) and 1 death for end-stage heart failure, respectively. Hospital readmissions decreased from 3.2 to 0.2 and from 4.2 to 0.2/year; late AF recurrences at of >120 beats/min were documented in 6% and 12%, respectively. Symptom score analysis including effort and rest dyspnea, exercise intolerance, weakness, and palpitation showed a significant improvement in both treatment groups, when acutely effective, in patients with paroxysmal and/or chronic AF. In conclusion, ablation of the AV junction shows a higher acute success rate compared with modulation of the AV node conduction in patients with drug refractory AF. Depending on the acute success, both approaches therefore were similarly effective in achieving long-term ventricular rate control and symptom score improvement.

Value of analysis of ST segment changes during tachycardia in determining type of narrow QRS complex tachycardia.

OBJECTIVES Repolarization changes during narrow QRS complex tachycardia were analyzed to differentiate the tachycardia mechanism and to guide the preliminary location of the accessory pathway. BACKGROUND Noninvasive determination of the mechanism of tachycardia is becoming increasingly important in view of the role of catheter ablation techniques for the cure of supraventricular tachycardia. METHODS We analyzed 159 12-lead electrocardiograms during narrow QRS complex tachycardia to evaluate 1) the tachycardia cycle; and 2) ST segment depression or T wave inversion, or both. Each patient underwent a complete electrophysiologic evaluation. RESULTS There were 13 atrial tachycardias, 57 atrioventricular (AV) node reentrant tachycardias and 89 AV reciprocating tachycardias. The mean RR cycle did not differ among types of tachycardia. ST segment depression >2 mm or T wave inversion, or both, was present more often in AV reciprocating tachycardia (57%) than in AV node tachycardia (25%). The magnitude of ST segment depression was greater in AV reciprocating tachycardia than in AV node tachycardia (mean +/- SD 1.3 +/- 1.6 vs. 0.7 +/- 0.8 mm, p < 0.005). In AV reciprocating tachycardia distinct patterns of repolarization changes and P wave configuration were associated with different sites of the accessory pathway. CONCLUSIONS The presence of ST segment depression >2 mm or T wave inversion, or both, during narrow QRS complex tachycardia suggests that AV reentry using an accessory pathway is the mechanism of the tachycardia. The phenomenon may be the consequence of a distinct pattern of retrograde atrial activation. Analysis of repolarization changes can guide preliminary localization of the accessory pathway even in the absence of ventricular preexcitation.

Feasibility of combined unipolar and bipolar voltage maps to improve sensitivity of endomyocardial biopsy

Background—Endomyocardial biopsy (EMB) has a low sensitivity. Electroanatomic voltage mapping (EVM) is effective in guiding EMB thanks to its ability in identifying and locating low-voltage regions. The analysis of unipolar EVM can correlate with epicardial pathological involvement. We evaluated the unipolar EVM in EMB areas to determine whether it can increase EMB sensitivity in diagnosing epicardial diseases. Methods and Results—We performed endocardial bipolar EVM-guided EMBs in 29 patients and we analyzed unipolar EVM at withdrawal sites. Eighty myocardial samples were collected (mean, 2.8±0.9; median, 3 fragments per patient) and 60 were suitable for histological analysis. Ten specimens (17%) were collected from an area with discordant normal bipolar/low-voltage unipolar EVM and they were diagnostic or suggestive for arrhythmogenic right ventricular dysplasia/cardiomyopathy in 6 patients, for myocarditis and sarcoidosis in 1 patient each. Six samples (10%) were collected from an area with discordant low-voltage bipolar/normal unipolar EVM and they showed nonspecific features. The sensitivity of unipolar EVMs for a diagnostic biopsy finding EMB was significantly higher compared with bipolar EVMs analyzed according to samples (P<0.01) and patients (P=0.008). The specificity of unipolar EMB was better than bipolar EMB when analyzed for all samples (P=0.0014) but the difference did not reach statistical significance when analyzed by patient (P=0.083). The diagnostic yield was 63.3% for the bipolar and 83.3% for the unipolar EVM. Conclusions—These findings suggest that use of a combined bipolar/unipolar map may be able to improve the diagnostic yield of endomyocardial ventricular biopsy.

Radiofrequency catheter ablation guided by noncontact mapping of ventricular tachycardia originating from an idiopathic left ventricular aneurysm

Idiopathic left ventricular aneurysm and diverticulum is known to be an arrhythmogenic substrate associated to ventricular tachyarrhythmias, generally based on a reentry mechanism. A case of a young woman affected by a monomorphic ventricular tachycardia, refractory to medical treatment, originating from an aneurysm of the membranous interventricular septum is reported. The left ventricular aneurysm was well characterized by multislice computed tomography and left ventricular angiography. Because of the nonsustained and poorly tolerated nature of the target arrhythmia, a noncontact mapping system was used to guide radiofrequency catheter ablation, allowing the elaboration of a three-dimensional activation map of the left ventricle on the basis of a ventricular tachycardia single beat. The procedure was acutely successful, and the patient remained free of ventricular tachycardia recurrences without antiarrhythmic drugs during a subsequent 6-month follow-up period. This is the first report of a successful radiofrequency catheter ablation guided by noncontact mapping system of a ventricular tachycardia originating from an idiopathic left ventricular aneurysm. This nonfluoroscopic mapping method allows a reliable reconstruction of the spatial relationships between the left ventricular main cavity and the aneurysm and can be safely and effectively used to map the ventricular tachycardia and guide the ablation procedure, particularly when conventional mapping is not indicated or not effective because of nonsustained or not-tolerated characters of ventricular tachycardia.

Hybrid Therapies for Ventricular Arrhythmias

In recent years several trials demonstrated the efficacy of implantable cardioverter‐defibrillation (ICD) therapy in reducing cardiac and total mortality in patients affected by rapid ventricular tachycardia (VT) and/or ventricular fibrillation. Nevertheless, ICD do not prevent arrhythmia recurrences, thus being a palliative and not a curative treatment modality. The tolerance to ICD therapy varies greatly, and within individuals, this leading to a nonuniform acceptance of this form of therapy. The very frequent occurrence of VT, defined as an arrhythmic storm, may be a life threatening condition. The majority of ICD patients is under antiarrhythmic drug therapy, to reduce episodes of VT or to make antitachycardia pacing more effective by slowing the tachycardia rate. Drug therapy, however, may cause additional problems, and does not represent the optimal solution. The prevention of VT and/or ventricular fibrillation episodes and excessive ICD therapy, remains a worthwhile goal. Radiofrequency catheter ablation (RFCA) is a curative approach, and can be expected to reduce the frequency of recurrent VT episodes in the majority of patients. The combination of these treatment modalities (ICD and RFCA) is often described as hybrid therapy, implying that the two treatments act providing some form of synergism. In experienced centers, RFCA is now performed, regardless of whether the VT rate is rapid and/or is hemodynamically unstable. Newer mapping and ablation techniques are now available, enhancing the acute success rate of the procedure. In this review the most recent application of VT catheter ablation and the use of advanced mapping and ablation techniques will be discussed.

Role of Intracardiac echocardiography in Atrial Fibrillation Ablation

In the recent years, several new evidences support catheter-based ablation as a treatment modality of atrial fibrillation (AF). Based on a plenty of different applications, intracardiac echocardiography (ICE) is now a well-established technology in complex electrophysiological procedures, in particular in AF ablation. ICE contributes to improve the efficacy and safety of such procedures defining the anatomical structures involved in ablation procedures and monitoring in real time possible complications. In particular ICE allows: a correct identification of the endocardial structures; a guidance of transseptal puncture; an assessment of accurate placement of the circular mapping catheter; an indirect evaluation of evolving lesions during radiofrequency (RF) energy delivery via visualization of micro and macrobubbles tissue heating; assessment of catheter contact with cardiac tissues. Recently, also the feasibility of the integration of electroanatomical mapping (EAM) and intracardiac echocardiography has been demonstrated, combining accurate real time anatomical information with electroanatomical data. As a matter of fact, different techniques and ablation strategies have been developed throughout the years. In the setting of balloon-based ablation systems, recently adopted by an increasing number of centers, ICE might have a role in the choice of appropriate balloon size and to confirm accurate occlusion of pulmonary veins. Furthermore, in the era of minimally fluoroscopic ablation, ICE has successfully provided a contribute in reducing fluoroscopy time. The purpose of this review is to summarize the current applications of ICE in catheter based ablation strategies of atrial fibrillation, focusing-on electronically phased-array ICE.

Ablate and Pace Therapy or AV Junction Modification for Medically Refractory Atrial Fibrillation

Currently available nonpharmacological techniques for ventricular rate control in patients with drug refractory atrial fibrillation (AF) include radiofrequency ablation of the atrioventricular (AV) junction with pacemaker implantation [1–4] and modulation of AV node conduction [5–8]. The former is an already established approach with a high success rate and predictable long-term effects; it also has limitations that include a nonphysiological pattern of ventricular activation and possible risk of late sudden death [9, 10]. Modulation of the AV node conduction has been introduced more recently into clinical practice, and, although it eliminates lifetime pacemaker dependence, it is less widely accepted because of a lower acute success rate, risk of inadvertent AV block, and persistence of irregular heartbeat. Since recent randomized studies [10, 11] comparing acute and medium term outcomes of the two techniques have given contrasting results, at the present time the relative merits of the two techniques are not well defined.