Patient: 74-year-old male with coronary artery disease and CABG; ejection fraction of 21%, paroxysmal atrial fibrillation; therapy with metoprolol.
Index arrhythmia: sustained monomorphic ventricular tachycardia, cycle length 360 ms.
ICD pulse generator: Tachos DR (Biotronik, Erlangen Germany)
Therapy: VF = shock; VT = antitachycardia pacing and cardioversion.
Bradycardia settings Mode: DDD 50-120 bpm. Mode switch = ON. AV = 180 ms.
Electrogram interpretation (See Figure 6.19b)
1. Comparison between atrial and ventricular rate: rate branch VV < AA.
2. Description of the atrial rhythm: the atrial electrogram shows a fast, almost regular atrial rhythm with CL of 190-210 ms. The morphology is varying, but not to an extreme degree. The atrial rhythm can be classified as atrial flutter or tachycardia.
3. Assessment of the onset of the tachyarrhythmia: not available here.
4. Characteristics of the ventricular electrogram during the tachyarrhythmia: the morphology of the ventricular activity is consistent during tachycardia, with one potentially different complex (after the pause of 507 ms in the second half). The atrioventricular relationship is compatible with atrial flutter and 2:1 conduction, which remains present also after the slowing of the atrial cycle to 210 ms. This explains the ventricular cycle length, initially about 380 ms, becoming 420 ms at the end of the rhythm strip.
Diagnosis: atrial flutter with predominantly 2:1 atrioventricular conduction.
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