A new interpretation of nonpulmonary vein substrates of the left atrium in patients with atrial fibrillation.

BACKGROUND: Substrate analysis of the left atrium in patients undergoing atrial fibrillation ablation has limitations when performed by means of simple bipolar acquisition. OBJECTIVE: To evaluate the incidence of low-voltage zones (LVZs) through maps constructed by means of various catheters: multipolar (MC), omnipolar (OC), and circular catheters (CMCs) with the 3D electro-anatomical systems (3d-S) CARTO3 and EnSite Precision. METHODS: To assess LVZs, we acquired maps by means of CMC and MC in the voltage range 0.05-0.5 mV in 70 consecutive patients in sinus rhythm. In the case of OC only, we made an intra-patient comparison of bipolar maps constructed by means of the along and across, and HD-Wave configurations of the EnSite 3d-S in the ranges of 0.05-0.5 and 0.5-1.0 mV. On the basis of this comparison, we chose the range that best identified LVZs as a set of different colors (SDC) compatible with patchy fibrosis (qualitative analysis). Subsequently, we detected the voltage values corresponding to purple and gray points, close to SDC, and the value inside corresponding to blue, green, and red colors, and we evaluated the color change in other voltage ranges. Finally, we performed a quantitative analysis of LVZs by applying the qualitative characteristics described above. RESULTS: On the basis of our settings, for OC, the optimal range identifying LVZs was 0.3-0.6 mV. OC revealed smaller LVZs than MC (P < .05 or P < .001), except in the lateral wall. No significant differences were observed between CMCs. CONCLUSIONS: In our experience, OC does not present the limits of bipolar HD maps, though further studies are needed in order to confirm that 0.3-0.6 mV is the optimal voltage range within which to identify LVZs.

Octogenarian Atrial Fibrillation Ablation with New NavX EnSite "Live View" Tool.

BACKGROUND: Atrial Fibrillation ablation in older patients represents a challenge to be addressed to ensure the improvement of the quality of life and survival of these patients. New mapping system tools can help to treat older patients because of its ability to simplify and reduce procedural risks. The new NavX EnSite "Live view" tool allows dynamic "beat to beat" activation and voltage mapping visualization in order to instantly recognize vein disconnection and minimize RF deliveries. METHODS: An 81-year old patient with paroxysmal AF and well-documented firing focus trigger underwent pulmonary veins isolation using NavX EnSite Precision, HD Grid multipolar catheter, and the new "Live view" tool. RESULTS: All pulmonary veins were successfully isolated with no procedural complications. "Live view" tool allows to perform shorter and safer procedure (total procedural time: 90 minutes, left atrium dwell time: 60 minutes, total RF delivery number: 78). CONCLUSION: "Live view tool" allows dynamic activation and voltage mapping in order to perform a safe and tailored approach to ablation, especially in older patients.

The nightmare ECG of a spontaneously aborted sudden cardiac death.

We present the case of a spontaneously aborted sudden cardiac death related to an high-rate ventricular tachycardia in an healthy man with bileaflet mitral valve prolapse. An effective treatment of the patient, with complete suppression of ventricular ectopic activity, was achieved only combining medical therapy, ICD and catheter ablation, thus overcoming the limitations of each approach.

Geometry and stability of dynamical systems.

We reconsider both the global and local stability of solutions of continuously evolving dynamical systems from a geometric perspective. We clarify that an unambiguous definition of stability generally requires the choice of additional geometric structure that is not intrinsic to the dynamical system itself. While we explain that global Lyapunov stability is based on the choice of seminorms on the vector bundle of perturbations, we propose a definition of local stability based on the choice of a linear connection. We show how this definition reproduces known stability criteria for second-order dynamical systems. In contrast to the general case, we show that the special geometry of Lagrangian systems provides completely intrinsic notions of global and local stability. We demonstrate that these do not suffer from the limitations occurring in the analysis of the Maupertuis-Jacobi geodesics associated to natural Lagrangian systems.