Case 28 Wide Complex Tachycardia in a Lady with Endstage Cardiomyopathy

Patient: 45-year-old female with dilated cardiomyopathy; left ventricular ejection fraction 0.26, congestive heart failure, and left bundle branch block (QRS width 122 ms). History of atrial tachyarrhythmia.

Index arrhythmia: sustained monomorphic ventricular tachycardia, cycle length 420 ms.

Complaint: palpitations; VT suspected on the ward. Almost asymptomatic. Electrogram

Figure 6.28a. From top to bottom: wide-band electrogram, markers, and marker channel. Markers: TD| = tachycardia sensing; VP = ventricular pace; VS = ventricular sense.

ICD pulse generator: Jewel AF 7250 (Medtronic Inc, Minneapolis, MN, USA).

Tachycardia settings

Detection: VF = 300 ms; VT = 460 ms. Discrimination: stability = 40 ms; PR Logic ON.

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

Bradycardia settings Mode: DDD 50-120 bpm. Mode switch = ON. AV = 180 ms.

Electrogram interpretation

Figure 6.28b.

Figure 6.28b.

1. Presence of tachyarrhythmia?: Yes.

2. Assessment of the onset of the tachyarrhythmia triggering the device: the marker channel demonstrates a stable ventricular rhythm with a consistent atrioventricular (AV) conduction pattern.

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 a fast atrial rhythm with an atrial cycle length ~ 320 ms. The atrial activity on the far-field electrogram shows a stable morphology (t). The atrial rhythm can either be an atrial tachycardia or an atrial flutter.

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 ~ 650 ms, with a stability of ~ 10 ms. During the stable ventricular rhythm, the marker channel demonstrates a consistent atrioventricular relationship with 2:1 atrioventricular conduction.

6. Effect of therapy: The marker channel shows atrial antitachycardia pacing (see below), which terminates the atrial tachyarrhythmia.

Figure 6.28c. From top to bottom: atrial and ventricular marker channels. Markers: AP = atrial pace; VP ventricular pace; VS = ventricular sense.

Diagnosis: atrial tachycardia or atrial flutter. Action: no further action.

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