A 64-year-old recipient of a Consulta CRT-D implanted for dilated cardiomyopathy, left ventricular ejection fraction of 20%, left bundle branch block and NYHA functional class III, received a shock 2 days after implantation of the device.
Inappropriate therapy early after device implantation is usually due to a) faulty connection of the pace/sense pins of the high voltage lead, or b) early dislodgement of the ventricular lead. Interrogation of the ICD can measure the capture threshold, R wave amplitude and the pacing and shock impedance. The lead position can be verified with a chest radiograph.
Episode of VF prompting the device to charge its capacitors. The charge is aborted, a second episode of VF is detected and treated with a shock of highest energy. When VF is first detected, the shock is aborted, sensing of the extracardiac signals temporarily stops and the underlying sinus rate is below the programmed detection interval. However, when the second episode of VF is detected, the device does not reconfirm VF and a shock is delivered after the second charge.
