Distribution of evoked delayed potential and delayed potential in a patient with subendocardial inferior infarction and transmural postero-lateral infarction: A case report.

A 47-year-old man with transmural posterolateral myocardial infarction (MI) and subendocardial inferior MI underwent catheter ablation for monomorphic ventricular tachycardia (VT). Right ventricular extra stimulation could unmask evoked delayed potentials in the subendocardial infarction area without delayed potentials in the sinus rhythm. Extra stimulation mapping for VT is useful for hidden VT substrates, particularly in the subendocardial infarction area.

Ripple map guided catheter ablation targeting abnormal atrial potentials during sinus rhythm for non-paroxysmal atrial fibrillation.

BACKGROUND: Abnormal atrial potential (AAP) during sinus rhythm may be a critical ablation target for atrial fibrillation. However, the assessment of local electrograms throughout the left atrium is difficult. Thus, we sought to investigate the effectiveness of Ripple map guided AAP ablation. METHODS AND RESULTS: AAP areas were determined by Ripple mapping on the CARTO system in 35 patients (Ripple group) by marking the area where small deflections persisted after the first deflection wavefront had passed. Following pulmonary vein isolation, AAP areas were ablated. If AAP areas were located on the left atrial posterior wall, the posterior wall was isolated. The outcome of this approach was compared with that of 66 patients who underwent an empirical linear ablation approach (control group). There were no differences in patient characteristics between the groups. The total radiofrequency application time and procedure time were shorter in the Ripple group than in the control group (radiofrequency application time, 48 ± 14 minutes vs 61 ± 13 minutes, P < .001; procedure time, 205 ± 30 minutes vs 221 ± 27 minutes, P = .013). Gastroparesis occurred in one patient in each group (P = .645), but in both cases this was relieved with conservative therapy. Kaplan-Meier analysis revealed that rate of freedom from atrial arrhythmia was higher in the Ripple group than in the control group (91% vs 74% during the 12 months' follow up; P = .040). CONCLUSION: Ripple map guided AAP ablation effectively suppressed atrial arrhythmia in patients with non-paroxysmal AF.

Transient, Marked ST-Segment Elevation During Successful Epicardial Substrate Ablation in a Patient With Brugada Syndrome.

A 37-year-old man with Brugada syndrome and frequent appropriate implantable cardioverter-defibrillator shocks received an epicardial substrate ablation. During the procedure to eliminate delayed potentials, transient, marked ST-segment elevation in lead V2 was observed, particularly in the anterior right ventricle with a borderline between normal and low-voltage areas. (Level of Difficulty: Intermediate.).

Local Left Ventricular Epicardial J Waves and Late Potentials in Brugada Syndrome Patients with Inferolateral Early Repolarization Pattern.

Background: Brugada syndrome (BrS) is characterized by J-point or ST-segment elevation on electrocardiograms (ECGs) and increased risk of ventricular fibrillation (VF). In BrS, epicardial depolarization abnormality with delayed potential on the right ventricular outflow tract is reportedly the predominant mechanism underlying VF. Yet VF occurrence is also associated with early repolarization (ER) pattern in the inferolateral ECG leads, which may represent the inferior and/or left lateral ventricular myocardium. The aim of this study was to examine epicardial electrograms recorded directly at the left ventricle (LV) in BrS patients after VF episodes. Methods: In 12 BrS patients who had experienced VF episodes and 17 control subjects, a multipolar catheter was introduced into the left lateral coronary vein for unipolar and bipolar electrogram recordings at the LV epicardium. Both inferior and lateral ER patterns on ECG were observed in three BrS patients and six control subjects. Results: In the epicardium, prominent J waves were detected using unipolar recording, and potentials after the QRS complex were detected using bipolar recording in three of the 12 BrS patients. These three patients also showed both inferior and lateral ER patterns on ECG. Neither prominent J waves nor potentials after the QRS complex were recorded at the endocardium of the LV in any of these three patients; nor were they seen at the epicardium in any of the control subjects. These features were accentuated on pilsicainide administration (n = 2) but diminished on constant atrial pacing (n = 3) and isoproterenol administration (n = 1). The J waves observed through unipolar recording coincided with the potentials after QRS complex observed through bipolar recording and with the inferolateral ER patterns on ECG. Conclusions: We recorded prominent J waves in unipolar electrogram and potentials after QRS complex in bipolar electrogram at the LV epicardium in BrS patients with global ER pattern. The prominent J waves coincided with the potentials after QRS complex and the inferolateral ER pattern on ECG. The characteristics of the inferolateral ER pattern on ECG in these patients primarily represent depolarization feature.

Visualization of the Critical Isthmus by Tracking Delayed Potential in Edited Windows for Scar-Related Ventricular Tachycardia.

BACKGROUND AND OBJECTIVES: Identifying the critical isthmus of slow conduction is crucial for successful treatment of scar-related ventricular tachycardia. Current 3D mapping is not designed for tracking the critical isthmus and may lead to a risk of extensive ablation. We edited the algorithm to track the delayed potential in order to visualize the isthmus and compared the edited map with a conventional map. SUBJECTS AND METHODS: We marked every point that showed delayed potential with blue color. After substrate mapping, we edited to reset the annotation from true ventricular potential to delayed potential and then changed the window of interest from the conventional zone (early, 50-60%; late, 40-50% from peak of QRS) to the edited zone (early, 80-90%; late, 10-20%) for every blue point. Finally, we compared the propagation maps before and after editing. RESULTS: We analyzed five scar-related ventricular tachycardia cases. In the propagation maps, the resetting map showed the critical isthmus and entrance and exit sites of tachycardia that showed figure 8 reentry. However, conventional maps only showed the earliest ventricular activation sites and searched for focal tachycardia. All of the tachycardia cases were terminated by ablating the area around the isthmus. CONCLUSION: Identifying the channel and direction of the critical isthmus by a new editing method to track delayed potential is essential in scar-related tachycardia.

Impact of catheter ablation of ventricular tachycardia in patients with prior myocardial infarctions.

BACKGROUND: Catheter ablation can reduce episodes of ventricular tachycardia (VT) after myocardial infarction (MI). However, the optimal endpoint of the ablation procedure remains unclear. METHODS: Fifty-one consecutive patients who received catheter ablation for VT after MI were included. The procedures targeted the isthmus of all the induced, sustained VTs. When the patients with induced VTs were hemodynamically stable, radiofrequency energy was delivered at the mid-diastolic potential recording site during VT. When the patients with VTs were hemodynamically unstable, the critical channel was identified at the delayed potential recording site, showing a good pace map, with a long stimulus-QRS interval. We delivered radiofrequency energy along the identified isthmus and across the exit of the circuit. RESULTS: At the end of the procedure, all VTs became non-inducible in 30 patients (59%) and some VTs were inducible in 21 patients (41%). During a mean of 40±29 months of follow-up, no VT or ventricular fibrillation recurred in 24 patients (80%) in the non-inducible group and in 12 patients (57%) in the inducible group, respectively (P=0.03). The identification of the channel during VT mapping tended to associate with no recurrence, although the difference was not statistically significant (P=0.2). Fourteen patients (27%) died during the follow-up period, mostly due to non-cardiac causes. CONCLUSIONS: The catheter ablation targeting the isthmus of prior-MIVT and non-inducibility at the end of the procedure can provide a satisfactory follow-up result.