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Funding Acknowledgements NO FUNDING Background Many studies demonstrated the importance of an optimal tissue contact to obtain safe and effective lesions and to improve the clinical outcome in ablation of cavotricuspid isthmus (CTI) for typical right atrial flutter (AFL). Data about a novel technology able to measure local tissue impedance (LI) providing a measure of tissue characteristics and lesion formation is still lacking in right atrium or CTI working. Purpose This analysis explores the relationship between LI measures and ablation spot lesion locations during ablation of CTI in common AFL patients (pts). Methods Consecutive pts undergoing AFL ablation from the CHARISMA registry were included. A novel RF ablation catheter with dedicated algorithm (DirectSense - DS -) was used to measure LI at the distal electrode of this catheter. Each targeted spot was characterized in terms of LI parameters during RF delivery at the lateral, intermediate and posterior portions of the CTI. Successful single RF ablation was defined according with a reduction of voltage (RedV) by at least 50% or split in two separate potentials (SPL). Ablation endpoint was the creation of bidirectional conduction block across the isthmus. Results A total of 135 ablation spot lesions were delivered in 20 pts (median 5 [3-11] lesions per pt): 7 (5%) at lateral, 88 (65%) at intermediate and 40 (30%) at posterior portions of the CTI. Acute success was obtained in all cases and no complications were observed. The median ablation time was 26 [17 – 36] seconds per lesion. 100 (74%) and 51 (38%) ablation spots were effective according with RedV or SPL, respectively. The mean LI was 106 ± 15Ω prior to ablation and 93 ± 13Ω after ablation (p Conclusion In our preliminary experience, measured LI before and after RF delivery and LI drop appear to be consistent and homogeneous across different CTI ablation locations. The magnitude of the LI drop was associated with effective lesion formation and conduction block.

Tetralogy of Fallot is the most common form of cyanotic congenital heart disease. Measurement of physical activity is usually performed as a routine part of the patient's cardiac evaluation. The aim of this study was to examine the exercise performance of young patients operated on for tetralogy of Fallot, assessing the possible influence of known negative prognostic factors related to the surgical repair. The study group comprised 41 consecutive patients (29 male and 12 female, ages 11.2 +/- 3.9 years, range 6-16 years) operated on for tetralogy of Fallot. Patients in the study group were divided in subgroups in relation to the age of surgical intervention (before or after 2 years of life), the surgical approach (combined transatrial/transpulmonary approach or right ventriculotomy), and the presence of aortopulmonary shunts prior to performing total correction. Their data were compared with those of 33 aged-matched asymptomatic control subjects (19 male and 14 female, ages 11.9 +/- 1.3 years, range 11-16 years). Blood pressure and heart rate measured at rest were similar between control and Fallot groups. A normal increase in systolic blood pressure was observed in response to exercise intensity for all subgroups. No significant difference between control and Fallot groups was found under conditions of mild or moderate exercise or for diastolic blood pressure at rest and in response to exercise. Lower maximal heart rate and systolic blood pressure values were recorded in all patients when compared with the control subjects. Significant differences in peak workload were detected between control and Fallot groups and between the control and each subgroup; however, no difference was found between subgroups. In conclusion, despite their very satisfactory clinical status, all patients showed a reduced peak workload, irrespective of the surgical approach, age at surgery, and aortopulmonary shunts prior to performing total correction.

Aim of the study was to address if mechanical dyssinchrony measured by Tissue Doppler Echocardiography (TDE) has prognostic implications in patients with LBBB and stable HF. Population and methods: 78 patients (mean age 68+13y; 42 male) with complete LBBB (QRS >120 msec) and stable HF (II NYHA class >3 months in optimal pharmacological therapy) underwent standard Doppler echo. Pulsed TDE was performed using four basal LV segments and one right lateral ventricular segment to assess the time to onset systolic contraction wave from R wave on ECG (Ts). The difference of Ts between the most delayed LV segment and RV lateral wall was considered as interventricular delay (InterV-del). Intraventricular delay (IntraV-del) was the difference among Ts of the LV segments An index of global ventricular asynchrony (GVA) was obtained by the sum of IntraV-del and InterV-del. Patients were followed and cardiac events such as death, worsening of heart failure and need of cardiac resynchronization therapy were recorded. Results: The mean value of EF was 36.4+9.7 and of GVA was 154.5+56.4 msec). GVA resulted inversely related to EF(r=-0.42 p 160 msec (AUC=0.88; p