Atrial low voltage areas: A comparison between atrial fibrillation and sinus rhythm.

BACKGROUND: Atrial fibrosis can promote atrial fibrillation (AF). Electroanatomic mapping (EAM) can provide information regarding local voltage abnormalities that may be used as a surrogate marker for fibrosis. Specific voltage cut-off values have been reproduced accurately to identify fibrosis in the ventricles, but these values are not well defined in atrial tissue. METHODS: This study is a prospective single-center study. Patients with persistent AF referred for ablation were included. EAM was performed before ablation. We recorded bipolar signals, first in AF and later in sinus rhythm (SR). Two thresholds delimited low-voltage areas (LVA), 0.5 and 0.3 mV. We compared LVA extension between maps in SR and AF in each patient. RESULTS: A total of 23 patients were included in the study. The percentage of points with voltage lower than 0.5 mV and 0.3 mV was significantly higher in maps in AF compared with maps in SR: 38.2% of points < 0.5 mV in AF vs. 22.9% in SR (p < 0.001); 22.3% of points < 0.3 mV in AF vs. 14% in SR (p < 0.001). Areas with reduced voltage were significantly larger in maps in AF (0.5 mV threshold, mean area in AF 41.3 ± 42.5 cm2 vs. 11.7 ± 17.9 cm2 in SR, p < 0.001; 0.3 mV threshold, mean area in AF 15.6 ± 22.1 cm2 vs. 6.2 ± 11.5 cm2 in SR, p < 0.001). CONCLUSIONS: Using the same voltage thresholds, LVA extension in AF is greater than in SR in patients with persistent AF. These findings provide arguments for defining a different atrial fibrosis threshold based on EAM rhythm.

Viabilidad del desfibrilador automático implantable subcutáneo en un paciente con pectum excavatum / Feasibility of a subcutaneous implantable cardioverter-defibrillator in a patient with pectus excavatum

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Evaluation of a near-zero fluoroscopic approach for catheter ablation in patients with congenital heart disease.

PURPOSE: Radiation exposure (RE) is a matter of concern for patients with congenital heart disease (CHD) who not infrequently need multiple interventional procedures under fluoroscopy guidance. We sought to evaluate the safety and feasibility of a minimally fluoroscopic approach in patients with CHD undergoing catheter ablation using a new image integration module (IIM). METHODS: Consecutive patients with CHD undergoing catheter ablation using the Carto Univu™ IIM were included. A near-zero fluoroscopy procedure was defined by an effective dose (ED) ≤ 1 mSv. RE parameters (total fluoroscopy time [TFT], total dose area product [tDAP], and ED), ablation outcomes, and complications were evaluated. RESULTS: Fifty-five patients with CHD underwent 63 ablation procedures (supraventricular tachycardia, n = 53; ventricular tachycardia, n = 10). The CHD was simple in 25%, moderate in 42%, and complex in 33%. The use of the IIM resulted in very low levels of RE (median TFT 0.13 min [IQR 0-1.04], median tDAP 54.5 cGy cm2 [IQR 9.5-176.4], median ED 0.136 mSv [IQR 0.02-0.49]). Patients with complex CHD had significantly higher RE when compared with patients with simple and moderate defects. A total of 56/63 ablation procedures (89%) were performed with an ED ≤ 1 mSv. One patient developed sinus node dysfunction requiring pacemaker implantation. CONCLUSIONS: The use of a minimally fluoroscopic approach was safe and feasible resulting in very low RE during catheter ablation of patients with CHD. A near-zero fluoroscopy ablation was possible in up to 89% of the procedures.

Myocardial Contraction during the Diastolic Isovolumetric Period: Analysis of Longitudinal Strain by Means of Speckle Tracking Echocardiography.

BACKGROUND: According to the ventricular myocardial band model, the diastolic isovolumetric period is a contraction phenomenon. Our objective was to employ speckle-tracking echocardiography (STE) to analyze myocardial deformation of the left ventricle (LV) and to confirm if it supports the myocardial band model. METHODS: This was a prospective observational study in which 90 healthy volunteers were recruited. We evaluated different types of postsystolic shortening (PSS) from an LV longitudinal strain study. Duration of latest deformation (LD) was calculated as the time from the start of the QRS complex of the ECG to the latest longitudinal deformation peak in the 18 segments of the LV. RESULTS: The mean age of our subjects was 50.3 ± 11.1 years. PSS was observed in 48.4% of the 1620 LV segments studied (19.8%, 13.5%, and 15.1% in the basal, medial, and apical regions, respectively). PSS was more frequent in the basal, medial septal, and apical anteroseptal segments (>50%). LD peaked in the interventricular septum and in the basal segments of the LV. CONCLUSIONS: The pattern of PSS and LD revealed by STE suggests there is contraction in the postsystolic phase of the cardiac cycle. The anatomical location of the segments in which this contraction is most frequently observed corresponds to the main path of the ascending component of the myocardial band. This contraction can be attributed to the protodiastolic untwisting of the LV.

Utility of high density multielectrode mapping during ablation of scar-related ventricular tachycardia.

INTRODUCTION: Multielectrode mapping catheters (MEMC) allow the performance of high resolution and density maps but the utility of these catheters in ventricular tachycardia (VT) ablation procedures has not been yet widely described. We sought to evaluate the utility of a MEMC during scar-related VT ablation procedures. METHODS: Eighty-five consecutive scar-related VT ablation procedures were performed in 81 patients. In the first 26 procedures, a standard 3.5-mm tip linear catheter was employed for endocardial/epicardial mapping (control group). In the following 59 procedures mapping was performed with a MEMC (study group). Procedural time, LV endocardial and epicardial mapping time, complications and ablation outcomes were compared. RESULTS: The use of the MEMC resulted in a significant shortening of the endocardial and epicardial mapping times (38 ± 15 minutes vs. 56 ± 24 minutes for endocardial LV mapping in the study and control group, respectively, P = 0.001; and 28 ± 9 minutes vs 41 ± 16 minutes, for epicardial mapping, P = 0.011) as well as the total procedural time (177 ± 53 minutes vs. 206 ± 50 minutes, respectively, P = 0.02). The mapping density was also significantly increased in the study group (mean endocardial LV points: 2,143 ± 1,419 vs. 485 ± 174, for the study and control group, respectively, P < 0.0001), specially within the scar area (49.6 ± 34 points/cm2 vs. 8.4 ± 4.6 points/cm2 , P < 0.001). No differences in acute and long-term follow-up outcomes were observed. CONCLUSIONS: High-density multielectrode mapping is associated with a significant reduction of procedural and mapping times and a significant increase of mapping density without affecting outcomes in patients with scar-related VT.