case_images: PMC7252794_01
case_images: A 12-lead electrocardiogram that demonstrates a wide complex rhythm with pacemaker spikes preceding QRS complexes. The ventricular rate is approximately 440 ms (125 bpm).
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case_images: An initial electrocardiogram (ECG) demonstrated a wide complex rhythm at a rate of 120 bpm with evidence of pacer spikes preceding the QRS complexes (Figure 1).
case_images: Intracardiac markers from the patient with the presenting arrhythmia's implantable cardioverter-defibrillator demonstrate an ongoing ventricular sensed rhythm at a cycle length of 490-560 ms with atrioventricular dissociation and biventricular pacing on sensed beats. An atrial tachycardia at a cycle length of 500 msec is also evident. Markers are suggestive of a ventricular sense response algorithm. Ab = atrial blanking; as = atrial sensing; TS = ventricular tachycardia sense; BVS = biventricular pacing on a ventricular sensed beat.
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case_images: PMC7252794_01_icrm-08-2590-g002.jpg
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case_images: Subsequent examination of the patient's implantable cardioverter-defibrillator (ICD) demonstrated an ongoing ventricular sensed rhythm at a cycle length of 490-560 ms with AV isorhythmic dissociation and biventricular pacing on the ventricular sensed beats (Figure 2).
case_images: A 12-lead electrocardiogram with inhibition of pacing that demonstrates an underlying ventricular tachycardia at a cycle length of 540 ms (112 bpm) of a right bundle branch, left superior axis morphology.
case_images: icrm-08-2590-g003.jpg
case_images: PMC7252794_01_icrm-08-2590-g003.jpg
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case_images: Figure 3 that demonstrates a bizarrely appearing wide complex tachycardia of right bundle branch morphology, left superior axis at a cycle length of 540 ms. Following discovery of this observation, the patient deteriorated hemodynamically, becoming hypotensive (74/55 mmHg).