Tilt Table Testing of Young Adult Patients: Improved Speed and Sensitivity Using an Isoproterenol Bolus and a Continuous 60° Tilt

The tilt table is a diagnostic device used to induce vagal syncope and determine etiology. Sensitivity enhancing techniques, such as the administration of isoproterenol, can be applied to children and young adults to compensate for the otherwise low sensitivity (20%-30%) observed in that population. This study describes an improved test that offers a simplified approach while decreasing the amount of time involved by up to 50%, without compromising sensitivity. This 45-minute procedure relies on sensitization with isoproterenol administered as a 2- to 8-μg bolus instead of a continuous infusion. The isoproterenol is injected at the 30th minute of a 45-minute 60° tilt test without returning the patient to the supine position. In this study, the isoproterenol bolus tilt test was found to be "positive" in 24 of 30 patients reporting unexplained syncope: 10 cases before the 30th minute (11.2 ± 8.4 min) and 14 cases after administration of 5.1 ± 1,9 μg of isoproterenol.     

Ablation of Post‐Myocardial Infarction Focal Ventricular Tachycardia

In the chronic phase of myocardial infarction, the presence of scar areas allows the development of macro‐reentries which become the most frequent mechanism underlying ventricular tachycardia (VT). A focal mechanism has been already described in the presence of scar in animal models or in humans but only during surgery. We report a case of focal automatic VT arising from postinfarction scar fibrosis, successfully mapped and ablated during an electro‐physiological procedure. (PACE 2010; 904–906)     

Slow Pathway Radiofrequency Ablation in Patients with AVNRT: Junctional Rhythm is Less Frequent during Magnetic Navigation Ablation Than with the Conventional Technique

Introduction: The occurrence of accelerated junctional rhythm (JR) during radiofrequency ablation of the slow pathway in patients with atrioventricular nodal reentrant tachycardia (AVNRT) is frequent. The aim of the present study was to compare the occurrence of JR during magnetic remote catheter ablation to the conventional manual ablation.
Methods and Results: Twenty six patients (males: seven; age: 51 ± 15 years) underwent slow pathway ablation with magnetic navigation (MN) system (Niobe, Stereotaxis Inc., St. Louis, MO, USA) and were compared to a control group of 11 patients (males: three; age: 53 ± 16 years) treated with conventional manual ablation. A 4-mm nonirrigated tip catheter was used in both groups with a maximum of 30 W and 60°C. Acute success was obtained in all patients. In the MN group, three patients out of 24 had no junctional beat (JB) at all and seven patients had 10 or less JB. In contrast, in the conventional group no patient had less than 10 JB. The mean number of JB in the MN group was 66 ± 94.9 (0–410) and 200 ± 243.1 (43–914) in the control group (P = 0.019). In the MN group one patient had a first-degree atrioventricular block. No other complication occurred.
Conclusions: Magnetic remote catheter ablation of AVNRT is effective and is associated with less JB than the manual conventional technique. Therefore, JB may not be considered as a mandatory indicator for successful AVNRT ablation with MN system. (PACE 2010; 11–15)