Blocking the pulmonary vein to left atrium conduction in addition to the entrance block enhances clinical efficacy in atrial fibrillation ablation

Background: The unidirectional pulmonary vein (PV) to left atrium (LA) conduction after achieving PV entrance block has not been evaluated. Methods: Circumferential PV isolation was performed in 573 consecutive patients with atrial fibrillation (AF). The unidirectional PV to LA conduction and its influence on clinical outcomes were evaluated. Results: A total of 341 ipsilateral PVs (29.7%) with spontaneous activities (SAs) were documented in 231 patients (40.3%). The unidirectional PV to LA conduction was confirmed in 11 ipsilateral PVs (3.2%) of 11 patients (4.8%). Patients were classified to three groups: Group A (had unidirectional PV to LA conduction during SAs), Group B (with SAs but without PV to LA conduction), and Group C (without SAs). During a 30‐minute observation, the reconnection incidence was higher in Group A (45.4%) than in Group B (13.9%, P = 0.042) and Group C (11.5%, P = 0.018). The reconnection time was shorter in Group A (10.8 ± 9.8 minutes) than that in Group B (20.7 ± 8.0 minutes, P = 0.037) and Group C (21.2 ± 8.2 minutes, P = 0.022). All 11 PVs were successfully isolated and bidirectional block was achieved. Conclusion: Unidirectional entrance block with SAs in PVs may not be a good indication of complete PV isolation. Bidirectional block of the PV‐LA junction can reduce the acute PV reconnection and may reduce the chronic AF recurrence in patients undergoing circumferential PV isolation.(PACE 2012; 1–8)     

Escape Passive Learning: 10 steps to Building an Escape Room

Escape rooms have become a popular way to engage students in active learning and provide innovative ways to learn. This article provides an overview of escape room use and outcomes from the higher education literature and describes their use at a large US midwestern college of nursing nurse practitioner program. Recommendations regarding design, implementation and evaluation are reviewed, and a 10-step process is shared to summarize how faculty can develop their escape room.     

Novel SuperMap feature of dipole charge density mapping technique offers advantages for redo catheter ablation in highly symptomatic patients with inappropriate sinus tachycardia: A case series

Ablation procedures using classical sequential mapping systems may fail to eliminate IAST. The AcQMap dipole charge density mapping technique may offer improved accuracy and has a potential added value for the ultimate success of eliminating IAST. The use of the AcQMap should be considered for redo, as well as first line therapy for patients with symptomatic IAST.     

Use of advanced mapping systems to guide ablation in complex cases: experience with noncontact mapping and electroanatomic mapping systems

OBJECTIVE: This report describes our experience with noncontact mapping and electroanatomic mapping in complex ablations, which are defined as ablations done after failure of conventional ablation. MATERIAL AND METHODS: Patients were included (N = 68; 49% with structural heart disease) in whom previous ablation failed and in whom a second procedure was done with advanced mapping. Non-contact mapping was used in 17 patients, electroanatomic mapping in 36, and both noncontact and electroanatomic mapping in 15. Arrhythmias included focal atrial tachycardia (n = 16), reentrant atrial tachycardia (n = 14), right ventricular outflow tachycardia (n = 10), post-myocardial infarction ventricular tachycardia (n = 9), and others (n = 19). RESULTS: Acute success at the second ablation was achieved in 79% of patients. At 20 +/- 9 months after the procedure, 69% of these patients reported having significantly fewer symptoms than before the second ablation, and 51% were free of symptoms. Only 16% were using antiarrhythmic medications. Complications included a small pericardial effusion in two patients, hypotension in one patient, and a femoral pseudoaneurysm in another. CONCLUSIONS: Advanced mapping is a useful and safe adjunct for catheter ablation after ablation has failed in patients with complex substrate.     

Fetal heart rate tracing interpretation in cases of fetal heart block: A case series

Simple assessment of FHR baseline variability can differentiate second‐degree heart block (SHB) from complete heart block (CHB). In cases of SHB, antepartum NST can be reliably used for fetal surveillance. Intrapartum assessment of FHR variability and accelerations is useful to select cases for safe vaginal delivery.     

Trans-myocardial bipolar electrogram: A strategy for mapping and determining efficacy of bipolar ablation of deep foci

Mapping and ablation of intramural ventricular tachycardia (VT) remain a challenge. We developed a trans-myocardial electrogram recording across distal tips of two separate ablation catheters placed on contralateral sides of the myocardium to record a trans-myocardial bipole and a novel pacing electrode configuration. This trans-myocardial bipole was applied during bipolar ablation in a patient with septal VT. Local activation in this trans-myocardial bipole was similar to the earliest activation recorded from detailed activation maps from both sides of the septum. Pacing from this trans-myocardial bipole resulted in a perfect morphology match. After bipolar ablation, the trans-myocardial bipolar voltage decreased by 82%, and pacing threshold increased by 800%. These findings correlated with VT noninducibility.     

A case of bidirectional conduction block within the superior vena cava induced by cryoballoon pulmonary vein isolation

A 53‐year‐old male underwent a pulmonary vein isolation (PVI) of atrial fibrillation (AF) with a second‐generation cryoballoon (CB). Although the patient maintained sinus rhythm after the PVI, a superior vena cava (SVC) fibrillation was recorded by a circular‐multipolar‐electrode catheter positioned inside the SVC that suggested conduction block between the right atrium (RA)‐SVC connection. An adenosine triphosphate intravenous injection induced a dormant reconnection of the SVC myocardial sleeve and converted sinus rhythm to an AF rhythm. This case demonstrated that a CB application for the isolation of a right superior pulmonary vein could induce an electrical conduction block between the RA‐SVC connection.     

An Unusual Case of Pacemaker Failure: Complete Disconnection of Connector Block and Battery of a Subpectorally Implanted Dual Chamber Pacemaker

MELLERT, F., et al. : An Unusual Case of Pacemaker Failure: Complete Disconnection of Connector Block and Battery of a Subpectorally Implanted Dual Chamber Pacemaker. Local trauma to patients with implanted pacemaker devices may result in lead fracture or breakage of the lead socket with leakage of fluid into the connector system. This report describes an unusual case of complete entrance and exit block in a subpectorally implanted dual chamber pacemaker due to total disconnection and dislodgement of header block and battery part. Damage may be caused by an interaction of machine fatigue/manufacturing defective and fixation of the header with unusual movability of the battery, leading to breakage with intermittent malfunction and consecutive bradycardia and syncope.     

Characterization of a long linear thermolesion in rabbit atria by high density mapping

A major problem in radiofrequency ablation is to evaluate if linear atrial lesions are transmural and continuous. Characteristics of the atrial electrograms recorded from these lesions might be useful to determine the completeness of linear atrial lesions. In seven isolated perfused rabbit atria, a long transmural linear lesion was made with a hot needle (perfused with water of 80 degrees C) (width 2 +/- 0.2 mm). The lesion extended from the orifice of the superior caval vein to the A V ring. High density mapping (240 electrodes, 7.5 x 7.5 mm) of the right atrium was performed before and after the lesion. Complete bidirectional conduction block was confirmed by pacing close at either side of the lesion. No change in conduction or electrogram characteristics occurred outside the lesion. From the center of the lesion, low amplitude double potentials were recorded. The conduction delay around the lesion and the width of the double potentials showed a high correlation (R2 = 0.99) and were both dependent of the site of pacing. From the boundaries of the lesion towards its center, the amplitude and slope of the unipolar electrograms decreased exponentially by 72 +/- 5 and 85 +/- 3%. From the decay of these electrotonic potentials a space constant (lambda of 0.79 +/- 0.04 mm) could be calculated for the lesion. Unipolar electrograms recorded from a complete and transmural linear atrial lesion are electrotonic in nature. Their characteristics could be used to evaluate the width and depth of the lesion.     

Noncontact mapping of the left ventricle: insights from validation with transmural contact mapping

It is not clear whether the noncontact electrograms obtained using the EnSite system in the left ventricle resemble most closely endocardial, intramural, or epicardial contact electrograms or a summation of transmural electrograms. This study compared unipolar virtual electrograms from the EnSite system with unipolar contact electrograms from transmural plunge needle electrodes using a 256-channel mapping system. The study also evaluated the effects of differing activation sites (endocardial, intramural, or epicardial). A grid of 50-60 plunge needles was positioned in the left ventricles of eight male sheep. Each needle had four electrodes to record from the endocardium, two intramural sites, and the epicardium. Correlations between contact and noncontact electrograms were calculated on 32,242 electrograms. Noncontact electrograms correlated equally well in morphology and accuracy of timing with endocardial (0.88 +/- 0.15), intramural (0.87 +/- 0.15), epicardial (0.88 +/- 0.15), and transmural summation contact electrograms (0.89 +/- 0.14) during sinus rhythm, endocardial pacing, and epicardial pacing. There was a nonlinear relationship between noncontact electrogram accuracy as measured by correlation with the contact electrogram and distance from the multielectrode array (MEA): beyond 40 mm accuracy decreased rapidly. The accuracy of noncontact electrograms also decreased with increasing distance from the equator of the MEA. Virtual electrograms from noncontact mapping of normal left ventricles probably represent a summation of transmural activation. Noncontact mapping has similar accuracy with either endocardial or epicardial sites of origin of electrical activity provided the MEA is within 40 mm of the recording site.     

Multiple distinct right atrial endocardial origins in a patient with atrial tachycardia: mapping and ablation using noncontact mapping

Noncontact mapping identified the endocardial origins of four distinct atrial tachycardias in a young patient with drug refractory palpitations and effected successful ablation with no recurrence of symptoms in 5 months of follow-up.     

Nonfluoroscopic magnetic electroanatomic mapping to facilitate focal pulmonary veins ablation for paroxysmal atrial fibrillation

RF ablation of ectopic foci in the pulmonary veins (PVs) is a promising treatment for patients with paroxysmal AF. The aim of this study was to evaluate the feasibility of using nonfluoroscopic magnetic electroanatomic mapping of PV during spontaneous or induced ectopy to facilitate focal ablation procedure. The study included 35 patients with drug refractory paroxysmal AF who underwent focal RF ablation of the PV. In 10 (29%) patients, mapping and RF ablation procedures were performed using the nonfluoroscopic magnetic electroanatomic mapping system to enable automatic capture of the location and the timing of the ectopy. As a control, 25 patients underwent conventional endocardial activation mapping technique. There were no significant differences in the clinical characteristics between the two groups. Overall procedural duration was similar between them (199 +/- 52 vs 221 +/- 82 minutes, P > 0.05). However, the mean fluoroscopy time (25 +/- 6 vs 52 +/- 12 minutes, P = 0.01) and the mean number of RF applications (5 +/- 3 vs 12 +/- 9, P = 0.02) were significantly less in patients who underwent electroanatomic mapping. There were no significant differences between the two groups in the acute (90 vs 84%) and long-term success rate (60 vs 56%) after a mean follow-up of 12 +/- 9 months. In conclusion, RF ablation of ectopic foci using nonfluoroscopic magnetic electroanatomic mapping of PVs during spontaneous or induced ectopy is useful even in patients with a limited number of ectopy, and is associated with a similar success rate, but less fluoroscopy time and RF application compared to the conventional approach.     

Acute success and persistence of bidirectional conduction block in the cavotricuspid isthmus one month post cryocatheter ablation of common atrial flutter

INTRODUCTION: Cryoablation is successful in the treatment of common atrial flutter. Long-term clinical success is mainly dependent on persistence of bidirectional conduction block (BCB) in the inferior cavotricuspid isthmus (CTI). Only few data on persistence of BCB post cryoablation with the reported technique are available. This prospective study aimed to test efficacy of cryo energy and persistence of BCB in the CTI 1 month post cryoablation. METHODS: Cryoablation of the CTI was performed in 50 consecutive patients (64 +/- 12 years, 40 males) with symptomatic common atrial flutter using a novel 9 Fr 8-mm-tip catheter. BCB in the CTI 30 minutes following the final cryoapplication was the ablation endpoint. Thirty days post ablation, persistence of BCB was controlled by repeat electrophysiological study (EPS). RESULTS: In all patients BCB was achieved with a mean of 9 (IQR 7-17.5) cryo applications and a mean cryo time of 2,378 seconds (IQR 1,680-3,474 seconds). In 5 of 50 patients, common atrial flutter recurred within 1 month post cryoablation. In 30 of 32 recurrence-free patients, persistence of BCB was verified. In 2 patients, resumption of isthmus conduction was detectable. Including relapses, 81.1% of patients (30/37) showed persistence of BCB. No patients reported pain during cryoapplication. No procedural complications were observed. CONCLUSIONS: Cryoablation of the CTI using a large-tip catheter is feasible and safe in the treatment of common atrial flutter. Acute and short-term success rates are comparable to those reported for radiofrequency (RF) ablation. Besides short-term clinical success, the persistence of BCB demonstrates efficacy of the cryoablation technique.     

Case report: Cryoballoon ablation of the mitral isthmus using a novel mapping system

Perimitral atrial flutter is commonly treated by deployment of a mitral isthmus line. However, the creation of a contiguous, transmural linear lesion across the anterior mitral isthmus using radiofrequency energy ablation is technically challenging and can be associated with major complications. Herein, we describe the successful deployment of a superolateral mitral isthmus line using the 28‐mm cryoballoon in combination with a new mapping system.     

Unsuccessful AV nodal ablation in atrial fibrillation: an alternative method to achieve complete heart block

We report the case of an elderly patient who presented with poorly tolerated episodes of atrial arrhythmia refractory to medical treatment. AV node ablation was identified as the only alternative expected to be efficacious for symptom relief. However, this usually simple intervention failed. The goal of creating a complete AV block was finally achieved through ablation of the anterior fascicle of the His bundle, which represented the only pathway for residual conduction in this patient.     

Tachycardia circuit in typical atrial flutter: the role of a posterolateral line of block in the perpetuation of the tachycardia

BACKGROUND: The essential boundaries in typical atrial flutter (AF) are unknown. METHODS: To examine the role of the tricuspid annulus (TA) and posterolateral line of block (LB) in maintaining AF, single extrastimuli were delivered during AF both around the LB and the TA in 29 patients. Single extrastimuli were delivered from the superior, middle, and inferior third of the anterior LB, superior, middle, and inferior third of the posterior LB, and the superior, lateral, inferior, and septal portions of the TA. The longest coupling interval (LCI) of single extrastimuli that reset AF and subsequent return cycle (RC) were analyzed. RESULTS: The resetting response showed two patterns (groups 1 and 2). The differences between the AF cycle length (AFCL) and the LCI (AFCL-LCI) at the superior, lateral, inferior, and septal portions of the TA were the shortest, and were significantly shorter than those at the other sites (P < 0.0001) in group 1. However, the AFCL-LCI at the superior, middle, and inferior third of the anterior LB, and the superior, lateral, inferior, and septal portions of the TA were the shortest, and were significantly shorter than those at the other sites (P < 0.0001) in group 2. The difference between the RC and the AFCL exhibited the same two patterns, similar to the AFCL-LCI. In group 1, a single extrastimulus produced an artificial conduction across the LB, but AF was not reset. CONCLUSIONS: Two types of reentry circuits exist in AF; one has its essential reentry circuit confined to the TA and thus the LB acts as a bystander, while the LB and the TA are essential boundaries in the other one.     

Combining electromagnetic navigation and 3‐D mapping to reduce fluoroscopy time and achieve optimal CRT response

Implantation of cardiac resynchronization therapy (CRT) devices can be challenging, time consuming, and associated with high‐dose x‐ray exposure. We present the technique in which an electromagnetic navigation system (MediGuideTM, St. Jude Medical) and an electroanatomical three‐dimensional mapping system (EnSite NavX, St Jude Medical) are usefully combined for implanting implantable cardioverter defibrillator CRT devices with strong reduction of x‐ray exposure, and for targeting the most delayed regions in the activation maps avoiding scars for optimal CRT response.     

Use of advanced mapping and remote magnetic navigation to ablate left ventricular fascicular tachycardia

Ablation of idiopathic left ventricular, or fascicular tachycardia can be aided by electroanatomical mapping. The addition of a floppy, magnetically enabled ablation catheter may improve maneuvering as well as decrease mechanically induced arrhythmias and mechanical block. We describe a case of fascicular tachycardia in which both these modalities were used in a sequential fashion. Integration of these modalities should prove even more helpful.