This 53-year-old man presenting with hypertrophic cardiomyopathy, a >30-mm interventricular septal thickness, episodes of non-sustained VT and sinus node dysfunction, received a Fortify dual chamber ICD for a primary prevention indication. He was seen for a routine follow-up visit.
Main programmed parameters
- VF zone at 206 bpm and VT zone at 171 bpm
- 12 cycles in each the VF and the VT zones were needed for the diagnosis
- Maximum sensitivity set at 0.5 mV
- VF zone: 1 sequence of ATP during the charge of the capacitors, followed by two 36-J shocks, followed by four 40-J (maximum strength) shocks; VT zone: set to monitor
- Effective discrimination in the VT zone
- DDDR pacing mode at 60 bpm; VVI episode pacing mode; DDD post-shock pacing mode at 60 bpm
Tracing
1: Atrial paced, ventricular sensed rhythm (AP-VS);
2: VT with AV dissociation; the ventricular rate was initially slower than the VT or VF zones and was, therefore, classified as VS;
3: Acceleration of the ventricular rhythm, the ventricles were in the VT zone (T); VVI episode pacing mode after 3 T classified cycles; the slow atrial rate remained sensed (sinus node dysfunction), though the AS markers were no longer present;
4: Monitored diagnosis of VT (12 T classified cycles); triggered recording without delivery of therapy;
5: Spontaneous termination of VT;
6: Diagnosis of return to sinus rhythm after 3 consecutive VS.
Diagnosis of 8-sec episode of VT in the monitor arm (V>A arm).
In this patient, the interrogation of the memories retrieved several episodes of non-sustained VT in the monitor zone. In this patient, the interrogation of the memories retrieved several episodes of non-sustained VT in the monitor zone. The programming of this zone monitors the arrhythmias and prevents the delivery of unnecessary therapies, since, in this patient, all episodes of VT ended spontaneously. The programming of a wider zone of therapy, including this episode, would have prompted a sequence of unnecessary ATP at the end of the initial detection period.