Patient: 29-year-old male with surgically corrected complex congenital heart disease (double outlet right ventricle; malposition of the great arteries, VSD, and coarctation), left ventricular dysfunction, and superior vena cava syndrome, uses salbutamol inhalatorbecause he is asthmatic. QRS width 170 ms.
Index arrhythmia: sustained monomorphic ventricular tachycardia, cycle length 490 ms.
Detection: VF = 280 ms; fast VT = 240 ms; VT = 400 ms. Discrimination: stability = 30 ms; onset = 84%.
Therapy: VF = shock; fast VT = antitachycardia pacing and shock; VT = antitachycardia pacing.
Mode: VVI 40bpm; all fancy features off.
Electrogram interpretation (See Figure 6.7a)
1. Presence of tachycardia: yes.
2. Description of the onset: described by the device in the first strip as "gradual", which is not correct, when the intervals are considered.
3. Characteristics of the ventricular electrogram during the tachyarrhythmia: the morphology of the FF and NF ventricular activity is similar and as wide as the complexes after spontaneous slowing. Only a little notch in the last part of the QRS in the NF electrogram suggests a different activation, which can be as easily explained as aberrancy.
4. Additional criteria and effect of therapy: the tachycardia CL varies between 230 and 240 ms in the first strip, before the slowing and the criteria for VF are met, triggering a shock. This does not affect the rhythm, varying between 370 and 390 ms in the second tracing, triggering ATP, once more not altering the QRS pattern.
Diagnosis: uncertain - supraventricular tachycardia with wide QRS complexes remains possible (see figure 6.7b). Former electrograms showed a more distinctive tachycardia pattern. The tachogram (not shown, but very gradual) and the salbutamol use suggest atrial tachycardia.
Actions: Increase the number of intervals before detection or confirmation.
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