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Background: Data on atrial fibrillation (AF) ablation and outcomes are limited in patients with congenital heart disease (CHD). We aimed to investigate the characteristics of patients with CHD presenting for AF ablation and their outcomes. Methods: A multicenter, retrospective analysis was performed of patients with CHD undergoing AF ablation between 2004 and 2020 at 13 participating centers. The severity of CHD was classified using 2014 Pediatric and Congenital Electrophysiology Society/Heart Rhythm Society guidelines. Clinical data were collected. One-year complete procedural success was defined as freedom from atrial tachycardia or AF in the absence of antiarrhythmic drugs or including previously failed antiarrhythmic drugs (partial success). Results: Of 240 patients, 127 (53.4%) had persistent AF, 62.5% were male, and mean age was 55.2±13.3 years. CHD complexity categories included 147 (61.3%) simple, 68 (28.3%) intermediate, and 25 (10.4%) severe. The most common CHD type was atrial septal defect (n=78). More complex CHD conditions included transposition of the great arteries (n=14), anomalous pulmonary veins (n=13), tetralogy of Fallot (n=8), cor triatriatum (n=7), single ventricle physiology (n=2), among others. The majority (71.3%) of patients had trialed at least one antiarrhythmic drug. Forty-six patients (22.1%) had reduced systemic ventricular ejection fraction Conclusions: AF ablation in CHD was safe and resulted in AF control in a majority of patients, regardless of complexity. Future work should address the most appropriate ablation targets in this challenging population.

In this review, we emphasize the unique value of recording the activation sequence of the His bundle or right bundle branch (RB) for diagnoses of various supraventricular and fascicular tachycardias. A close analysis of the His to RB (H-RB) activation sequence can help differentiate various forms of supraventricular tachycardias, namely atrioventricular nodal reentry tachycardia from concealed nodofascicular tachycardia, a common clinical dilemma. Furthermore, bundle branch reentry tachycardia and fascicular tachycardias often are included in the differential diagnosis of supraventricular tachycardia with aberrancy, and the use of this technique can help the operator make the distinction between supraventricular tachycardias and these other forms of ventricular tachycardias using the His-Purkinje system. We show that this technique is enhanced by the use of multipolar catheters placed to span the proximal His to RB position to record the activation sequence between proximal His potential to the distal RB potential. This allows the operator to fully analyze the activation sequence in sinus rhythm as compared to that during tachycardia and may help target ablation of these arrhythmias. We argue that 3 patterns of H-RB activation are commonly identified—the anterograde H-RB pattern, the retrograde H-RB (right bundle to His bundle) pattern, and the chevron H-RB pattern (simultaneous proximal His and proximal RB activation)—and specific arrhythmias tend to be associated with specific H-RB activation sequences. We show that being able to record and categorize this H-RB relationship can be instrumental to the operator, along with standard pacing maneuvers, to make an arrhythmia diagnosis in complex tachycardia circuits. We highlight the importance of H-RB activation patterns in these complex tachycardias by means of case illustrations from our groups as well as from prior reports.

Background: Refractory ventricular fibrillation (VF) is a challenging clinical entity, for which ablation of triggering premature ventricular complexes is described. When premature ventricular complexes are infrequent and multifocal, the optimal treatment strategy is uncertain. Methods: We prospectively enrolled consecutive patients presenting with multiple implantable cardioverter-defibrillator shocks for VF refractory to antiarrhythmic drug therapy, exhibiting infrequent (≤3%), multifocal premature ventricular complexes (≥3 morphologies). Procedurally, VF was induced with rapid pacing and mapped, identifying sites of conduction slowing and rotation or rapid focal activation. VF electrical substrate ablation was then performed. Outcomes were compared against reference patients with VF who were unable or unwilling to undergo catheter ablation. The primary outcome was a composite of implantable cardioverter-defibrillator shock, electrical storm, or all-cause mortality. Results: VF was induced and mapped in 6 patients (60±10 years; left ventricular ejection fraction, 46±19%) with ischemic (n=3) and nonischemic cardiomyopathy. An average of 3.3±0.5 sites of localized reentry during VF were targeted for radiofrequency ablation (38.3±10.9 minutes) during sinus rhythm, rendering VF noninducible with pacing. Freedom from the primary outcome was 83% in the VF ablation group versus 17% in 6 nonablation reference patients at a median of 1.0 years (interquartile range, 0.5–1.5 years; P =0.046) of follow-up. Conclusions: VF electrical substrate ablation is associated with a reduction in the combined end point compared with the nonablation reference group. Additional work is required to understand the precise pathophysiologic changes that promote VF to improve preventative and therapeutic strategies.

Introduction: Ventricular arrhythmia (VA) mechanisms arising from the crux, summit, and epicardium are often not accessible from the endocardium. The 3.3Fr multipolar mapping catheters (3FMC) (Map-iT, Access Point Technologies, Rogers, MN) can be used to map deep within the coronary sinus (CS) branches and other locations difficult to access with standard catheters. Objective: We present a case series of and techniques for VA ablations guided by the 3FMC. Methods: We retrospectively reviewed VA ablations at 3 centers to describe the utility of the 3FMC in diagnosis and ablation of the arrhythmia. Results: We reviewed 33 patients who underwent VA ablations guided by the 3FMC. Patients (age 59.0 ± 15.4 years, 72% male, LVEF 41.5 ± 10.3%, 93% non-ischemic) had ventricular tachycardia (32%) or high-burden PVCs (68%). The 3FMC was used to interrogate the epicardium via the coronary sinus branches allowing interrogation of the LV crux (Fig. A) and LV summit (Fig. B). Early potentials in the poster-septal branch of CS guided alcohol ablation to focal site in septum not reachable by traditional catheters. Continuous signal on the 3FMC in the posterolateral branch of CS elucidated microreentry and guided more extensive epicardial ablation. Overall, the 3FMC measured signals 18.7 ± 11.3ms early and diagnosed 75% focal, 10% micro-reentrant, and 15% macro-reentrant VAs. Ablation was successful in 76% of cases. Conclusions: High definition mapping with the 3FMC allows diagnosis of VA mechanisms in locations not easily reachable by traditional catheters. Improved mapping of the CS branches enables interrogation and ablation planning of epicardial, summit, and crux VAs and may increase the likelihood of successful VA ablation.

Background: Septal left atrial flutter has been described de novo and has been associated with lower catheter ablation success rate. Objective: To describe the electrophysiological characteristics and results of catheter ablation in patients with septal atrial flutter presenting after atrial fibrillation (AF) ablation. Methods: We retrospectively reviewed patients who presented with atrial flutter after PVI at 3 different centers. These included patients who had undergone surgical ablation and extensive catheter ablation for AF. Results: The study included 13 patients with septal atrial flutter. 6 patients presented after surgical ablation (including LAA clipping). All patients had undergone PVI and posterior wall isolation. Figure shows the 12 lead ECG and 3D electroanatomic map in one patient after surgical ablation of AF. The 12 lead ECG shows positive P waves in inferior leads, flat in I and avL with early precordial transition. The 3D map shows early activation on both sides of the septum with early meets late on septal side of the mitral annulus. The voltage map showed lack of voltage in posterior wall. Entrainment mapping was helpful in identifying both sides of the septum including septal mitral annulus, anterior roof and coronary sinus as part of the circuit. Catheter ablation was acutely successful in terminating flutter in 70% of the patients. The cycle length prolonged in the remaining patients. There was early recurrence leading to success rate of 50% after single ablation. Conclusion: Septal flutter after extensive catheter ablation and surgical ablation for AF is associated with low voltage in posterior wall. It involves a large circuit including both sides of the septum, anterior roof and CS.

Background Detection of myocardial infarction (MI) traditionally requires ECG Q waves, which have poor sensitivity, or imaging, which is time consuming. We hypothesized that machine learning (ML) of the ECG could identify prior MI, but its accuracy may depend highly upon the architecture and parameters chosen. Purpose To compare ML architectures that predict prior MI from the ECG. Methods We curated ECGs in 608 patients seen in cardiology clinics at 2 centers. We transformed 12-lead ECGs to median beats in Frank (X, Y, Z) planes (fig. A). We tested 3 architectures: a 1D deep neural network (DNN), a 3D neural network, and a support vector machine (SVM). The 1D DNN used only temporal convolutions (fig B) while the 3D DNN uses a spatial convolution (fig C) prior to the fully-connected layer (fig. C). Predictive accuracy for history of MI was compared for all architectures (fig. D). Results Patients (61.4±14.5 years, 31.2% female) had a 28.7% (175/608) prevalence of prior MI. Optimized SVM of 6 features provided accuracy of 66.1% for identifying prior MI, similar to ECG Q wave analysis. 1D DDN had accuracy of 63.6% with an area under curve (AUC) of 0.625. 3D DNN outperformed 1D DNN and SVM, providing an accuracy of 71±5% (using k=5-fold cross validation), with an AUC of 0.730. Conclusion ECG machine learning can identify prior MI better than Q wave analysis, but is sensitive to technical parameters and specific computational architecture. It is important to develop a framework to enable robust comparisons of different ML studies and future refinements. Funding Acknowledgement Type of funding source: Public grant(s) – National budget only. Main funding source(s): National Institutes of Health - United States

Patient: Male, 78-year-old Final Diagnosis: Pulmonary vein stenosis Symptoms: Dyspnea Medication:— Clinical Procedure: Radiofrequency ablation • stenting of the pulmonary vein Specialty: Pulmonology Objective: Unusual clinical course Background: Pulmonary vein (PV) stenosis is a rare condition characterized by progressive luminal size reduction of one or more pulmonary veins (PVs), which can increase postcapillary pressure resulting in shortness of breath, cough, hemoptysis, and pulmonary hypertension (PH). The diagnosis of PV stenosis requires a high degree of suspicion. PV stenosis is a rare but recognized complication of catheter-based radiofrequency ablation (RFA) for atrial fibrillation (AF). Case Report: We present a case of a 78-year-old man who underwent a surgical MAZE procedure followed by catheter-based RFA to treat AF. He subsequently developed shortness of breath, exercise limitation, and PH. The patient was ultimately diagnosed with PV stenosis, which was a sequela of the RFA and the cause of his PH. The patient was treated by stenting of his PV, with improvement in his exercise capacity and PH. Follow-up imaging showed improved pulmonary blood flow and reduced pulmonary pressures. Conclusions: We conclude that PV stenosis should be high in the differential as the cause of dyspnea in patients with PH and a previous history of RFA for AF management. Early recognition and treatment can prevent complete occlusion of the affected PV and lead to an improvement in the patient’s symptoms and quality of life.

OBJECTIVE To investigate mechanisms by which atrial fibrillation (AF) may terminate during ablation near the pulmonary veins before the veins are isolated (PVI). INTRODUCTION It remains unstudied how AF may terminate during ablation before PVs are isolated, or how patients with PV reconnection can be arrhythmia-free. We studied patients in whom PV antral ablation terminated AF before PVI, using two independent mapping methods. METHODS We studied patients with AF referred for ablation, in whom biatrial contact basket electrograms were studied by both an activation/phase mapping method and by a second validated mapping method reported not to create false rotational activity. RESULTS In 22 patients (age 60.1 ± 10.4, 36% persistent AF), ablation at sites near the PVs terminated AF (77% to sinus rhythm) prior to PVI. AF propagation revealed rotational (n = 20) and focal (n = 2) patterns at sites of termination by mapping method 1 and method 2. Both methods showed organized sites that were spatially concordant (P

There is a need for consensus recommendations for ionizing radiation dose optimization during multimodality medical imaging in children with congenital and acquired heart disease (CAHD). These children often have complex diseases and may be exposed to a relatively high cumulative burden of ionizing radiation from medical imaging procedures, including cardiac computed tomography, nuclear cardiology studies, and fluoroscopically guided diagnostic and interventional catheterization and electrophysiology procedures. Although these imaging procedures are all essential to the care of children with CAHD and have contributed to meaningfully improved outcomes in these patients, exposure to ionizing radiation is associated with potential risks, including an increased lifetime attributable risk of cancer. The goal of these recommendations is to encourage informed imaging to achieve appropriate study quality at the lowest achievable dose. Other strategies to improve care include a patient-centered approach to imaging, emphasizing education and informed decision making and programmatic approaches to ensure appropriate dose monitoring. Looking ahead, there is a need for standardization of dose metrics across imaging modalities, so as to encourage comparative effectiveness studies across the spectrum of CAHD in children.

Aims Focal Impulse and Rotor Modulation (FIRM) uses 64-electrode basket catheters to identify atrial fibrillation (AF)-sustaining sites for ablation, with promising results in many studies. Accordingly, new basket designs are being tested by several groups. We set out to determine the procedural safety of adding basket mapping and map-guided ablation to conventional pulmonary vein isolation (PVI). Methods and results We collected 30 day procedural safety data in five US centres for consecutive patients undergoing FIRM plus PVI (FIRM-PVI) compared with contemporaneous controls undergoing PVI without FIRM. A total of 625 cases were included in this analysis: 325 FIRM-PVI and 300 PVI-controls. FIRM-PVI patients were more likely than PVI-controls to be male (83% vs. 66%, P

In the past year, there have been numerous advances in our understanding of arrhythmia mechanisms, diagnosis, and new therapies. We have seen advances in basic cardiac electrophysiology with data suggesting that secretoneurin may be a biomarker for patients at risk of ventricular arrhythmias, and we have learned of the potential role of an NPR-C (natriuretic peptide receptor-C) in atrial fibrosis and the role of an atrial specific 2-pore potassium channel TASK-1 as a therapeutic target for atrial fibrillation. We have seen studies demonstrating the role of sensory neurons in sleep apnea-related atrial fibrillation and the association between bariatric surgery and atrial fibrillation ablation outcomes. Artificial intelligence applied to electrocardiography has yielded estimates of age, sex, and overall health. We have seen new tools for collection of patient-centered outcomes following catheter ablation. There have been significant advances in the ability to identify ventricular tachycardia termination sites through high-density mapping of deceleration zones. We have learned that right ventricular dysfunction may be a predictor of survival benefit after implantable cardioverter-defibrillator implantation in patients with nonischemic cardiomyopathy. We have seen further insights into the role of His bundle pacing on improving outcomes. As our understanding of cardiac laminopathies advances, we may have new tools to predict arrhythmic event rates in gene carriers. Finally, we have seen numerous advances in the treatment of arrhythmias in patients with congenital heart disease.

Background Arrhythmias are a leading cause of death in adults with congenital heart disease (ACHD). While 24-48-hour monitors are often used to assess arrhythmia burden, extended continuous ambulatory rhythm monitors (ECAM) can record 2 weeks of data. The utility of this device and the arrhythmia burden identified beyond 48-hour monitoring have not been evaluated in the ACHD population. Additionally, the impact of ECAM has not been studied to determine management recommendations. Objective To address the preliminary question, we hypothesized that clinically significant arrhythmias would be detected on ECAM beyond 48 hours and this would lead to clinical management changes. Methods A single center retrospective cohort study of ACHD patients undergoing ECAM from June 2013 to May 2016 was performed. The number and type of arrhythmias detected within and beyond the first 48 hours of monitoring were compared using Kaplan-Meier curves and Cox proportional hazard models. Results Three hundred fourteen patients had monitors performed [median age 31 (IQR 25-41) years, 61% female). Significant arrhythmias were identified in 156 patients (50%), of which 46% were noted within 48 hours. A management change based on an arrhythmia was made in 49 patients (16%). Conclusions ECAM detects more clinically significant arrhythmias than standard 48-hour monitoring in ACHD patients. Management changes, including medication changes, further testing or imaging, and procedures, were made based on results of ECAM. Recommendations and guidelines have been made based on arrhythmias on 48-hour monitoring; the predictive ability and clinical consequence of arrhythmias found on ECAM are not yet known.

Background: The outcomes from pulmonary vein isolation (PVI) for atrial fibrillation (AF) are suboptimal, but the benefits of additional lesion sets remain unproven. Recent studies propose ablation of AF drivers improves outcomes over PVI, yet with conflicting reports in the literature. We undertook a systematic literature review and meta-analysis to determine outcomes from ablation of AF drivers in addition to PVI or as a stand-alone procedure. Methods: Database search was done using the terms atrial fibrillation and ablation or catheter ablation and driver or rotor or focal impulse or FIRM (Focal Impulse and Rotor Modulation). We pooled data using random effects model and assessed heterogeneity with I 2 statistic. Results: Seventeen studies met inclusion criteria, in a cohort size of 3294 patients. Adding AF driver ablation to PVI reported freedom from AF of 72.5% (confidence interval [CI], 62.1%–81.8%; P P P =0.02) for freedom from AF and an odds ratio of 1.8 (CI, 1.2–2.7; P P Conclusions: In controlled studies, the addition of AF driver ablation to PVI supports the possible benefit of a combined approach of AF driver ablation and PVI in improving single-procedure freedom from all arrhythmias. However, most studies are uncontrolled and are limited by substantial heterogeneity in outcomes. Large multicenter randomized trials are needed to precisely define the benefits of adding driver ablation to PVI.

Background: The mechanisms by which persistent atrial fibrillation (AF) terminates via localized ablation are not well understood. To address the hypothesis that sites where localized ablation terminates persistent AF have characteristics identifiable with activation mapping during AF, we systematically examined activation patterns acquired only in cases of unequivocal termination by ablation. Methods and Results: We recruited 57 patients with persistent AF undergoing ablation, in whom localized ablation terminated AF to sinus rhythm or organized tachycardia. For each site, we performed an offline analysis of unprocessed unipolar electrograms collected during AF from multipolar basket catheters using the maximum –dV/dt assignment to construct isochronal activation maps for multiple cycles. Additional computational modeling and phase analysis were used to study mechanisms of map variability. At all sites of AF termination, localized repetitive activation patterns were observed. Partial rotational circuits were observed in 26 of 57 (46%) cases, focal patterns in 19 of 57 (33%), and complete rotational activity in 12 of 57 (21%) cases. In computer simulations, incomplete segments of partial rotations coincided with areas of slow conduction characterized by complex, multicomponent electrograms, and variations in assigning activation times at such sites substantially altered mapped mechanisms. Conclusions: Local activation mapping at sites of termination of persistent AF showed repetitive patterns of rotational or focal activity. In computer simulations, complete rotational activation sequence was observed but was sensitive to assignment of activation timing particularly in segments of slow conduction. The observed phenomena of repetitive localized activation and the mechanism by which local ablation terminates putative AF drivers require further investigation.

Ventricular arrhythmias (ventricular tachycardia and ventricular fibrillation) are often associated with underlying structural heart disease and require prompt assessment and treatment. Acute treatment involves initial hemodynamic stabilization of the patient followed by suppressive treatment with pharmacologic and nonpharmacologic approaches for reducing the risk of recurrence of ventricular arrhythmias and potential development of sudden cardiac death. This article reviews acute antiarrhythmic drug therapy for ventricular arrhythmias based on the clinical presentation.

There is a need for consensus recommendations for ionizing radiation dose optimization during multimodality medical imaging in children with congenital and acquired heart disease (CAHD). These children often have complex diseases and may be exposed to a relatively high cumulative burden of ionizing radiation from medical imaging procedures, including cardiac computed tomography, nuclear cardiology studies, and fluoroscopically guided diagnostic and interventional catheterization and electrophysiology procedures. Although these imaging procedures are all essential to the care of children with CAHD and have contributed to meaningfully improved outcomes in these patients, exposure to ionizing radiation is associated with potential risks, including an increased lifetime attributable risk of cancer. The goal of these recommendations is to encourage informed imaging to achieve appropriate study quality at the lowest achievable dose. Other strategies to improve care include a patient-centered approach to imaging, emphasizing education and informed decision making and programmatic approaches to ensure appropriate dose monitoring. Looking ahead, there is a need for standardization of dose metrics across imaging modalities, so as to encourage comparative effectiveness studies across the spectrum of CAHD in children.

Background Because the His bundle is intrinsic to the circuit in orthodromic reciprocating tachycardia and remote from that of atrioventricular nodal reentrant tachycardia (AVNRT), pacing the His bundle during supraventricular tachycardia (SVT) may be useful to distinguish these arrhythmias. Objective The purpose of this study was to test the hypothesis that His overdrive pacing (HOP) would affect SVT immediately for orthodromic reciprocating tachycardia and in a delayed manner for AVNRT. Methods Once SVT was induced, HOP was performed by pacing the His bundle 10–30 ms faster than the SVT cycle length. The maneuver was determined to have entered the tachycardia circuit when a nonfused His-capture beat advanced or delayed the subsequent atrial electrogram by ≥10 ms or when the tachycardia was terminated. The number of beats required to enter each tachycardia with HOP was recorded. Results HOP was performed during 66 SVTs (26 atrioventricular reciprocating tachycardia [AVRT] and 40 AVNRT). Entry into the tachycardia within 1 beat had sensitivity of 92%, specificity of 92%, positive predictive value (PPV) of 89% and negative predictive value (NPV) of 95% to confirm the diagnosis of AVRT. A cutoff ≥3 beats to enter the circuit had sensitivity of 90%, specificity of 92%, PPV of 95% and NPV of 86% to confirm the diagnosis of AVNRT. HOP had sensitivity, specificity, PPV, and NPV of 100% for distinguishing septal AVRT from atypical AVNRT. Conclusion HOP during SVT is a novel technique for distinguishing orthodromic reciprocating tachycardia from AVNRT. It can reliably distinguish between these arrhythmias with high sensitivity and specificity.

Background: Human embryonic stem cell-derived cardiomyocytes (hESC-CMs) were recently shown to be capable of electromechanical integration following direct injection into intact or recently injured guinea pig hearts, and hESC-CM transplantation in recently injured hearts correlated with improvements in contractile function and a reduction in the incidence of arrhythmias. The present study was aimed at determining the ability of hESC-CMs to integrate and modulate electrical stability following transplantation in a chronic model of cardiac injury. Methods and Results: At 28 days following cardiac cryoinjury, guinea pigs underwent intracardiac injection of hESC-CMs, noncardiac hESC derivatives (non-CMs), or vehicle. Histology confirmed partial remuscularization of the infarct zone in hESC-CM recipients while non-CM recipients showed heterogeneous xenografts. The 3 experimental groups showed no significant difference in the left ventricular dimensions or fractional shortening by echocardiography or in the incidence of spontaneous arrhythmias by telemetric monitoring. Although recipients of hESC-CMs and vehicle showed a similar incidence of arrhythmias induced by programmed electrical stimulation at 4 weeks posttransplantation, non-CM recipients proved to be highly inducible, with a ∼3-fold greater incidence of induced arrhythmias. In parallel studies, we investigated the ability of hESC-CMs to couple with host myocardium in chronically injured hearts by the intravital imaging of hESC-CM grafts that stably expressed a fluorescent reporter of graft activation, the genetically encoded calcium sensor GCaMP3. In this work, we found that only ∼38% (5 of 13) of recipients of GCaMP3+ hESC-CMs showed fluorescent transients that were coupled to the host electrocardiogram. Conclusions: Human embryonic stem cell-derived cardiomyocytes engraft in chronically injured hearts without increasing the incidence of arrhythmias, but their electromechanical integration is more limited than previously reported following their transplantation in a subacute injury model. Moreover, non-CM grafts may promote arrhythmias under certain conditions, a finding that underscores the need for input preparations of high cardiac purity.

Transplantation studies in mice and rats have shown that human embryonic-stem-cell-derived cardiomyocytes (hESC-CMs) can improve the function of infarcted hearts, but two critical issues related to their electrophysiological behaviour in vivo remain unresolved. First, the risk of arrhythmias following hESC-CM transplantation in injured hearts has not been determined. Second, the electromechanical integration of hESC-CMs in injured hearts has not been demonstrated, so it is unclear whether these cells improve contractile function directly through addition of new force-generating units. Here we use a guinea-pig model to show that hESC-CM grafts in injured hearts protect against arrhythmias and can contract synchronously with host muscle. Injured hearts with hESC-CM grafts show improved mechanical function and a significantly reduced incidence of both spontaneous and induced ventricular tachycardia. To assess the activity of hESC-CM grafts in vivo, we transplanted hESC-CMs expressing the genetically encoded calcium sensor, GCaMP3 (refs 4, 5). By correlating the GCaMP3 fluorescent signal with the host ECG, we found that grafts in uninjured hearts have consistent 1:1 host–graft coupling. Grafts in injured hearts are more heterogeneous and typically include both coupled and uncoupled regions. Thus, human myocardial grafts meet physiological criteria for true heart regeneration, providing support for the continued development of hESC-based cardiac therapies for both mechanical and electrical repair.

We thank Dr. Mohanty and colleagues for their letter concerning our study [(1)][1]. Their philosophy that it is unnecessary to map paroxysmal atrial fibrillation (AF) highlights our central point that “paroxysmal” or “persistent” encompasses heterogeneous AF populations who are often

Ictal asystole is being recognized as a potential mechanism of sudden unexplained death in epilepsy (SUDEP). We report a case of a patient without known cardiac disease presenting with ictal asystole resulting in syncope, trauma, and need for pacemaker implantation. The management of ictal asystole is also briefly reviewed. This case is notable for the asystolic episode wholly captured on video-electroencephalogram/electrocardiogram, the serious risk of trauma and death posed to the patient, and its implications for the mechanism of ictal asystole. This report will alert physicians to the possibility of ictal arrhythmias as a cause of syncope and SUDEP in vulnerable patients. (PACE 2011; 1–4)

Cardiac tamponade in systemic sclerosis is rare. We report four cases of SSc with hemodynamically significant pericardial effusions associated with pulmonary arterial hypertension, three of whom died, two following pericardiocentesis. Of 26 SSc cases reported in the literature with large pericardial effusions, seven were associated with PAH. Including our series, the mortality rate is 55%.The potential contributory role of PAH in the development of pericardial effusion and the management implications are explored. In SSc patients with hemodynamically significant pericardial effusions and severe pulmonary hypertension, initial stabilization of pulmonary artery pressure and right heart function with vasoactive therapy and then cautious pericardial drainage should be considered.

This article reports an interesting case of a narrow complex tachycardia presenting the diagnostic dilemma of differentiating atrioventricular nodal reentrant tachycardia (AVNRT) from junctional tachycardia. It proposes delivering late-coupled premature atrial complexes during the tachycardia with short ventriculo-atrial interval as a diagnostic maneuver to differentiate AVNRT from junctional tachycardia in the electrophysiology laboratory. Treatments of these arrhythmias vary, and making the appropriate diagnosis of supraventricular tachycardia is essential to providing effective arrhythmia management.

Typical atrial flutter ablation success rate is high, however clinical outcome remains limited by frequent co-morbid atrial fibrillation. A 52-year-old woman presents for “routine” dofetilide loading for persistent atrial fibrillation with rapid ventricular response after developing dyspnea on

The aim of this study was to determine the feasibility and accuracy of wall motion score index (WMSI) and myocardial performance index (MPI) for measuring regional and global left ventricular (LV) function with use of high-resolution echocardiography after myocardial infarction (MI) in mice. In 48 mice, myocardial infarction was induced by ligation in the middle of the left anterior descending coronary artery. Echocardiography was performed under anesthesia at baseline and 1 mo after MI. WMSI was analyzed by a 16-segment model on short-axis views, and wall motion was scored as 1 for normal, 2 for hypokinetic, 3 for akinetic, 4 for dyskinetic, and 5 for aneurysmal. WMSI was calculated as the sum of scores divided by the total number of segments. MPI was calculated on the basis of isovolumetric contraction time (IVCT), isovolumetric relaxation time (IVRT), and ejection time (ET): MPI = (IVCT + IVRT)/ET. We measured LV ejection fraction (LVEF), end-systolic and end-diastolic volumes (ESV and EDV), fractional shortening (FS), and infarct size (IS). LVEF at 4 wk after MI was reduced at 32.8 ± 9.0%. Linear correlation analyses showed that WMSI (1.6 ± 0.3) correlated with LVEF ( r = −0.84, P < 0.0005), FS ( r = −0.43, P = 0.003), and IS (34.3 ± 15.3%, r = 0.86, P < 0.0005). MPI (0.67 ± 0.09) correlated with LVEF ( r = −0.67, P < 0.0005) and IS ( r = 0.72, P < 0.0005). MPI also correlated with mitral inflow velocity ( r = −0.68, P < 0.0005) and deceleration time ( r = −0.42, P = 0.003). Stepwise regression analysis revealed that WMSI was independently associated with IS. IS, FS, mitral inflow velocity, and deceleration time were independent determinants of MPI. In conclusion, echocardiographic assessments of WMSI and MPI in mice are feasible and correlate strongly with two-dimensional measurement of LV function and IS. These novel parameters provide additional noninvasive assessment of regional and global LV function in mice after MI.

Background One of the clinical hallmarks of constrictive pericarditis is the pericardial knock, a high-pitched early diastolic heart sound. Making the clinical diagnosis of constrictive pericarditis is challenging, as is accurate auscultation of the pericardial knock. Hypothesis We sought to assess the utility of a computerized acoustic cardiographic device in the assessment of the pericardial knock in patients with constrictive pericarditis. Methods We report a case series in which computerized acoustic cardiography (Audicor, Inovise Medical Inc., Portland, OR) is performed in patients with constrictive pericarditis. Results Three patients with constrictive pericarditis underwent computerized acoustic cardiographic recordings at the time of cardiac catheterization. In each case, initial physical examination by the internist and referring cardiologist did not appreciate a pericardial knock. Acoustic cardiography demonstrated a high-pitched early diastolic sound in each case. Time-frequency representation analyses showed the high-frequency components of the pericardial knock sound. Repeat acoustic cardiography demonstrated resolution of the pericardial knock after pericardiectomy in two patients. Conclusions Non-invasive computerized acoustic cardiography can demonstrate the high-pitched pericardial knock in patients with constrictive pericarditis. This may aid the bedside assessment of patients with diastolic heart failure, improving the clinician's ability to appreciate the ausculatory findings in constrictive pericarditis. Copyright © 2007 Wiley Periodicals, Inc.

Previous observations have reported that the number of pacing stimuli required to entrain a tachycardia varies on the basis of arrhythmia type and location, but a quantitative formulation of the number needed to entrain (NNE) that unifies these observations has not been characterized.We sought to investigate the relationship between the number of pacing stimulations, the tachycardia cycle length (TCL), the overdrive pacing cycle length (PCL), and the postpacing interval (PPI) to accurately estimate the timing of tachycardia entrainment.First, we detailed a mathematical derivation unifying electrophysiological parameters with empirical confirmation in 2 patients undergoing catheter ablation of typical atrial flutter. Second, we validated our formula in 44 patients who underwent various catheter ablation procedures. For accuracy, we corrected for rate-related changes in conduction velocity.We derived the equations NNE = |(PPI - TCL)/(TCL - PCL)| + 1 and Tachycardia advancement = (NNE - 1) × (TCL - PCL) - (PPI - TCL), which state that the NNE and the amount of tachycardia advancement on the first resetting stimulation are determined using regularly measured intracardiac parameters. In the retrospective cohort, the observed PPI - TCL highly correlated with the predicted PPI - TCL (mean difference 5.8 ms; r = 0.97; P.001), calculated as PPI - TCL = (NNE - 1) × (TCL - PCL) - tachycardia advancement.The number of pacing stimulations required to entrain a reentrant tachycardia is predictable at any PCL after correcting for cycle length-dependent changes in conduction velocity. This relationship unifies established empirically derived diagnostic and mapping criteria for supraventricular tachycardia and ventricular tachycardia. This relationship may help elucidate when antitachycardia pacing episodes are ineffective or proarrhythmic and could potentially serve as a theoretical basis to customize antitachycardia pacing settings for improved safety and effectiveness.

The mouse is an important model for the development of therapeutic stem cell/bone marrow cell implantation to treat ischemic myocardium. However, its small heart size hampers accurate implantation into the left ventricular (LV) wall. Precise injections have required surgical visualization of the heart, which is subject to complications and is impractical for delayed or repeated injections. Furthermore, the thickness of the myocardium is comparable to the length of a needle bevel, so surgical exposure does not prevent inadvertent injection into the LV cavity. We describe the use of high-resolution echocardiography to guide nonsurgical injections accurately into the mouse myocardial wall. We optimized this system by using a mixture of ultrasound contrast and fluorescent microspheres injected into the myocardium, which enabled us to interpret the ultrasound image of the needle during injection. Quantitative dye injection studies demonstrated that guided closed-chest injections and open-chest injections deliver comparable amounts of injectate to the myocardium. We successfully used this system in a mouse myocardial infarction model to target the injection of labeled cells to a region adjacent to the infarct. Intentional injection of tracer into the LV cavity resulted in a small accumulation in the myocardium, suggesting that nonguided cell injections into mouse hearts may appear to be successful even if the majority of the injectate is lost in the chamber. The use of this system will allow more precise cellular implantation into the mouse myocardium by accurately guiding injections to desired locations, confirming successful implantation of cells, in a clinically relevant time frame.

Little is known about the distribution of cardiac sources of embolism among African-Americans with cryptogenic cerebrovascular events. We compared the prevalence of potential cardiac sources of embolism between black and white patients referred to our laboratory for transesophageal echocardiographic (TEE) evaluation of unexplained stroke or transient ischemic attack. Records were reviewed to exclude subjects with high-risk cardiac or vascular disorders likely to explain the index event. Of 297 patients satisfying the inclusion criteria, 196 were white and 87 black. Potential cardioembolic sources were significantly less common in blacks than in whites (adjusted odds ratio [OR], 0.44; 95% confidence interval [CI] 0.26 to 0.75), and related largely to the difference in prevalence of interatrial communication (OR 0.40; 95% CI 0.21 to 0.74). In contrast, African-Americans had a higher prevalence of left ventricular (LV) hypertrophy (OR 3.50; 95% CI 1.97 to 6.22), and particularly, moderate or severe hypertrophy (OR 4.03; 95% CI 1.88 to 9.65) compared with whites. In conclusion, in African-Americans with unexplained cerebrovascular events, the yield of TEE for potential cardioembolic sources, and especially interatrial communication, is lower than in their white counterparts. African-Americans exhibit a substantially higher prevalence of LV hypertrophy, which may be a marker for a higher burden of subclinical cerebrovascular disease involved in the pathogenesis of cryptogenic cerebral ischemia in this population.

The understanding of human thymic function and evaluation of its contribution to T cell homeostasis are matters of great importance. Here we report the development of a novel assay to quantitate the frequency and diversity of recent thymic emigrants (RTEs) in the peripheral blood of humans. Such cells were defined by the presence of T cell receptor (TCR) rearrangement deletion circles (DCs), episomal byproducts of TCR-beta V(D)J rearrangement. DCs were detected in T cells in the thymus, cord blood, and adult peripheral blood. In the peripheral blood of adults aged 22 to 76 years, their frequency was highest in the CD4(+)CD45RA(+) CD62L(+) subpopulation of naive T cells. TCR DCs were also observed in other subpopulations of peripheral blood T cells, including those with the CD4(+)CD45RO(-)CD62L(+) and CD4(+)CD45RO(+)CD62L(+) phenotypes. RTEs were observed to have more than one Vbeta rearrangement, suggesting that replenishment of the repertoire in the adult is at least oligoclonal. These results demonstrate that the normal adult thymus continues to contribute, even in older individuals, a diverse set of new T cells to the peripheral circulation.

i b v v p T t t u a t t n i i f ase summary n 81-year-old man with hypertension, hyperlipidemia, and oronary artery disease (CAD) was admitted to the hospital ith substernal chest pressure. He had a history of sick sinus yndrome and had undergone implantation of a dual-chamer pacemaker (Identity ADx DR model 5380, St. Jude edical, Sylmar, CA, USA) 7 days prior to admission. On resentation, the patient complained of palpitations and alaise that started after pacemaker implantation. Given the atient’s substernal chest pain, coronary angiography was erformed, which revealed no new lesions to explain his ymptoms. During hospitalization, while the patient was ying in bed, he experienced an episode of chest pain similar o his symptoms as an outpatient. Simultaneous ECG reealed an atrial-paced, narrow QRS complex rhythm at a apid rate of 110 bpm (Figure 1). A subsequent ECG reealed an atrial-paced rhythm at 60 bpm, with pacing stimli seen at the peak of the T wave and an intermittent trial-paced, ventricular-sensed rhythm once again at 110 pm (Figure 2). What is the mechanism of the rhythm? Is he pacemaker functioning appropriately?

A 55-YEAR-OLD MAN WITH A HISTORY OF hypercholesterolemia and symptomatic premature ventricular complexes treated with a -blocker was admitted to an outside hospital with acute-onset left-sided chest pressure, palpitations, and lightheadedness. Paramedics at the scene obtained a 12-lead electrocardiogram (ECG) revealing a wide-complex tachycardia at 248 beats per minute (Figure 1), which self-terminated as the patient was being prepared for direct-current cardioversion. The patient was then treated with chewable aspirin and intravenous lidocaine. In the emergency department he reported recurrent palpitations, and a repeated ECG showed atrial fibrillation with occasional wide QRS complexes that resembled the clinical tachycardia (Figure 2). Intravenous heparin sodium and amiodarone infusions were initiated. Cardiac biomarkers showed a mildly elevated level of troponin T (0.08 ng/mL [0.08 g/L]). Transthoracic echocardiography showed mild global left ventricular dysfunction with an ejection fraction of 45%. Urgent cardiac catheterization revealed an 80% proximal lesion in the left anterior descending artery and a 90% right coronary artery lesion that were treated with the implantation of 2 everolimus-eluting stents. The patient continued to have runs of wide-complex tachycardia after revascularization, and he was transferred to our facility for possible implantable cardioverterdefibrillator (ICD) with the diagnosis of sustained ventricular tachycardia (VT) in the setting of ischemic heart disease and a mildly depressed ejection fraction. Questions: What is the most likely diagnosis of the tachycardia seen in Figure 1? Should this patient receive an ICD?

Ablation Multiform Fascicular Tachycardia. Introduction: Fascicular tachycardia (FT) is an uncommon cause of monomorphic sustained ventricular tachycardia (VT). We describe 6 cases of FT with multiform QRS morphologies. Methods and Results : Six of 823 consecutive VT cases were retrospectively analyzed and found attributable to FT with multiform QRS patterns, with 3 cases exhibiting narrow QRS VT as well. All underwent electrophysiology study including fascicular potential mapping, entrainment pacing, and electroanatomic mapping. The first 3 cases describe similar multiform VT patterns with successful ablation in the upper mid septum. Initially, a right bundle branch block (RBBB) VT with superior axis was induced. Radiofrequency catheter ablation (RFCA) targeting the left posterior fascicle (LPF) resulted in a second VT with RBBB inferior axis. RFCA in the upper septum just apical to the LBB potential abolished VT in all cases. Cases 4 and 5 showed RBBB VT with alternating fascicular block compatible with upper septal dependent VT, resulting in bundle branch reentrant VT (BBRT) after ablation of LPF and left anterior fascicle (LAF). Finally, Cases 5 and 6 demonstrated spontaneous shift in QRS morphology during VT, implicating participation of a third fascicle. In Case 6, successful ablation was achieved over the proximal LAF, likely representing insertion of the auxiliary fascicle near the proximal LAF. Conclusions : Multiform FTs show a reentrant mechanism using multiple fascicular branches. We hypothesize that retrograde conduction over the septal fascicle produces alternate fascicular patterns as well as narrow VT forms. Ablation of the respective fascicle was successful in abolishing FT but does not preclude development of BBRT unless septal fascicle is targeted and ablated. (J Cardiovasc Electrophysiol, Vol. 24, pp. 297-304, March 2013)

Ictal asystole is being recognized as a potential mechanism of sudden unexplained death in epilepsy (SUDEP). We report a case of a patient without known cardiac disease presenting with ictal asystole resulting in syncope, trauma, and need for pacemaker implantation. The management of ictal asystole is also briefly reviewed. This case is notable for the asystolic episode wholly captured on video-electroencephalogram/electrocardiogram, the serious risk of trauma and death posed to the patient, and its implications for the mechanism of ictal asystole. This report will alert physicians to the possibility of ictal arrhythmias as a cause of syncope and SUDEP in vulnerable patients.

We compared therapeutic benefits of intramyocardial injection of unfractionated bone marrow cells (BMCs) versus BMC extract as treatments for myocardial infarction (MI), using closed-chest ultrasound-guided injection at a clinically relevant time post-MI. MI was induced in mice and the animals treated at day 3 with either: (i) BMCs from green fluorescent protein (GFP)-expressing mice (n = 14), (ii) BMC extract (n = 14), or (iii) saline control (n = 14). Six animals per group were used for histology at day 6 and the rest followed to day 28 for functional analysis. Ejection fraction was similarly improved in the BMC and extract groups versus control (40.6 +/- 3.4 and 39.1 +/- 2.9% versus 33.2 +/- 5.0%, P0.05) with smaller scar sizes. At day 6 but not day 28, both therapies led to significantly higher capillary area and number of arterioles versus control. At day 6, BMCs increased the number of cycling cardiomyocytes (CMs) versus control whereas extract therapy resulted in significant reduction in the number of apoptotic CMs at the border zone (BZ) versus control. Intracellular components within BMCs can enhance vascularity, reduce infarct size, improve cardiac function, and influence CM apoptosis and cycling early after therapy following MI. Intact cells are not necessary and death of implanted cells may be a major component of the benefit.