Figure 2 - available via license: Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International
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A: Intracardiac electrocardiogram (EGM) of supraventricular tachycardia (SVT) with 2:1 AV conduction. A right bundle branch block is seen in V 1 . The earliest atrial activation is at the right atrial (RA) septum. B: Intracardiac EGM of SVT with 1:1 AV conduction with a VA time of 18 ms. The 2:1 tachycardia converted to 1:1 tachycardia after premature ventricular contractions were delivered. The atrial activation is identical for both tachycardias. CS 5 coronary sinus; D 5 distal; HRA 5 high right atrium; P 5 proximal; RVa 5 right ventricle apex.
Contexts in source publication
Context 1
... catheter manipulation a 2:1 A:V tachycardia was initiated with catheter premature atrial complexes and AH prolongation. The earliest atrial activation during the 2:1 tachycardia was on the septum ( Figure 2A). The surface ECG shows superiorly directed P waves with positive p wave in V 1 , and right bundle branch aberrancy. ...
Citations
... Implantable cardioverter defibrillators (ICDs) are frequently implanted for both primary and secondary prevention of sudden cardiac death (SCD) from ventricular arrhythmias (VA) [1]. Although ICD therapies can be life-saving, ICDs also deliver inappropriate therapies approximately 12-14% of the time for sinus tachycardia, atrial fibrillation, supraventricular tachycardia (SVT), or lead/device malfunction [2,3]. Aside from being painful and adversely affecting quality of life, both appropriate and inappropriate ICD shocks have been associated with increased mortality [4]. ...
Background:
Implantable cardioverter defibrillators (ICDs) are typically programed with both ventricular tachycardia (VT) and ventricular fibrillation (VF) treatment zones. Biotronik and Abbott ICDs do not increment the VT counter when the tachycardia accelerates to the VF zone, which could result in a prolonged delay in tachycardia detection.
Methods:
Patients with Biotronik and Abbott ICDs receiving care at Veterans Affairs facilities in Northern California were identified. Patient information and device tracings for patients with any ICD therapies were examined to assess for possible delayed tachycardia detection.
Results:
Among 52 patients with Biotronik ICDs, 8 (15%) experienced appropriate ICD therapy over a median follow-up of 29 months. Among 68 patients with Abbott ICDs, 26 (38%) experienced appropriate ICD therapy over a median follow-up of 83 months. Three of the patients with Biotronik ICDs who received appropriate therapy experienced a delay in VT/VF detection due to the tachycardia rate oscillating between the VT and VF treatment zones (longest 31.2 s on detection), compared with four of the patients with Abbott ICDs (longest 4.1 s on the detection and 8 s on redetect). One of the patients with a Biotronik ICD experienced recurrent syncope associated with delayed detection and another died on the day of delayed detection. One of the patients with an Abbott ICD experienced syncope.
Conclusions:
Because contemporary Biotronik and Abbott ICDs freeze the VT counters when tachycardia is in the VF zone, ICD therapies can be markedly delayed when the tachycardia oscillates between the VT and VF zone.
