Case 36 Widecomplex Tachycardia after Cardiac Surgery

Patient: 41-year-old male patient, dilated cardiomyopathy, left ventricular ejection fraction 20%, congestive heart failure, left ventricular assist device, artificial respiration.

Index arrhythmia: primary prevention for sudden cardiac death. Observation: no treatment for ventricular tachycardia.

Figure 6.36a. Continuous ECG strip obtained during monitoring after cardiac surgery. The second tracing is the respiration.

ICD pulse generator: Entrust D154VRC (Medtronic Inc, Minneapolis, MN, USA).

Tachycardia settings

Detection: VF = 290 ms; FVT = 250 ms; VT = 370 ms. Discrimination: stability = 30 ms; onset = 81%; wavelet ON, 70%. Therapy: VF = shock; FVT and VT = antitachycardia pacing and cardioversion.

Bradycardia settings

Mode: VVI 40bpm. (See Figure 6.36b)

Electrogram (See Figure 6.36c)

Interpretation

1. Interval plot: the interval versus time plot demonstrates a sudden decrease of ventricular intervals. The arrhythmia was classified as SVT despite the sudden onset of the tachyarrhythmia as shown in the interval plot.

2. Presence of tachyarrhythmia?: Yes.

3. Assessment of the onset of the tachyarrhythmia triggering the device: a premature beat (1) initiates a fast tachyarrhythmia (2).

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Figure 6.36a. Continuous ECG strip obtained during monitoring after cardiac surgery. The second tracing is the respiration.

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Figure 6.36b. Interval plot

Figure 6.36c. From top to bottom: near-field ventricular electrogram, wide-band ventricular electrogram, and marker channel. Markers: TS = sense in ventricular tachycardia window; VS = ventricular sense.

4. Characteristics of the ventricular electrogram during the tachyarrhythmia: the morphology of the ventricular activity is consistent in both ventricular electrograms. The morphology cannot be compared to the baseline rhythm, as no electrogram was stored before arrhythmia onset. Additional information can be provided by the stored electrogram after arrhythmia termination (see figure 6.36d). The ventricular rhythm has a cycle length of ~ 290 ms, with a stability of ~ 10 ms.

5. Characteristics of the ventricular electrogram after termination of the tachyarrhythmia: the morphology after arrhythmia termination changed as compared to the morphology during the tachyarrhythmia.

Electrogram (See Figure 6.36d)

Diagnosis: fast monomorphic ventricular tachycardia with late coupled ventricular premature beat and slight irregularity. The device classified the

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