Figure 6.42c. From top to bottom: marker channel. Markers: AP = atrial pacing; AR = atrial refractory sense; AS = atrial sensing; CD = charge delivered; VP = ventricular pace; VS = ventricular sense.

Case 43 Incessant Tachycardia

Patient: 49-year-old female with ischemic heart disease, left ventricular ejection fraction 0.29, QRS width 170 ms, right bundle branch block.

Index arrhythmia: out-of-hospital cardiac arrest, ventricular fibrillation.

Complaint: shortness of breath, recurrent palpitations; admitted at hospital due to decompensation, incessant tachycardia (see ECG).

Figure 6.43a.

ICD pulse generator: Gem DR 7271 (Medtronic Inc, Minneapolis, MN, USA). Tachycardia settings

Detection: VF = 280 ms; fast VT = 340 ms; VT = 440 ms. Discrimination: stability = 40 ms; PR Logic ON.

Therapy: VF = shock; fast VT and VT = antitachycardia pacing and cardioversion.

Bradycardia settings

Mode: DDD 40-115 bpm.

Electrogram interpretation

Figure 6.43b. From top to bottom: surface electrocardiogram, marker channel, and ventricular electrogram. Markers: AR = atrial refractory sense; AS = atrial sensing; VS = ventricular sense.

1. Presence of tachyarrhythmia?: Yes.

2. Assessment of the onset of the tachyarrhythmia triggering the device: not available in this electrogram.

3. Comparison between atrial and ventricular rate: rate branch VV < AA.

4. Description of the atrial rhythm: the atrial activity on the marker channel shows an atrial rhythm with an atrial cycle length ~ 700 ms, without relation with the ventricular electrogram.

5. Characteristics of the ventricular electrogram during the tachyarrhythmia: the morphology of the ventricular activity is consistent in the electrogram. The ventricular rhythm has a cycle length of ~ 480 ms, with a stability of ^ 10 ms.

Diagnosis: slow ventricular tachycardia with absence of ventriculoatrial conduction.

Action: reprogrammation of the ventricular detection zone, hospitalization to diagnose the cause of the slow VT.

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