Spiky Ventricular Tachycardia

Report:

Pacemaker-mediated tachycardia 118/min 10

Comment:

In view of the identical complexes in the admission ECG (Fig 81a) it is hard to believe that Casualty staff thought they were treating a genuine VT with amiodarone. Not to mention the same pacing spikes (bipolar, small, but clearly visible) in V4.

The differential diagnosis of paced tachycardia is discussed elsewhere46. This one is a relatively common endless loop tachycardia, dependent on sensed retrograde P waves to perpetuate itself. At first glance, this appears unlikely here: the retrograde VA block

is quite long, about 0.44”. What one needs to know is that the patient had a similarly long antegrade 1o AV block before he was paced (Fig 81b).[! XE "Retrograde VA conduction:first degree VA block" !]

The reason he became symptomatic is that his cardiovascular reserve was very poor. Anyway, amiodarone, given for the wrong reason, worked: he reverted to sinus rhythm, with atrial-sensed ventricular pacing as on admission.

Fig 81a. Sinus rhythm with LAA and paced QRS complexes.

Fig 81b. Long 1o AVB in the pre-pacing ECG.

Fig 82. 80 year old woman with permanent pacemaker. There are 5 electrocardiographic abnormalities present. Is there any evidence of the pacemaker malfunction?

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