DESCRIPTION

This is really a pumped-up version of the wandering atrial pacemaker. From a descriptive perspective, it’s as if you took the meandering professor from our last example and gave him six double espressos to drink: imagine him running around now, bouncing off walls (and the occasional ceiling), with eyes bugged out and hair frizzed and standing on end. That’s multifocal atrial tachycardia, with multiple premature atrial complexes with at least three different P morphologies (see arrows), and frequently bursts of supraventricular tachycardia as well.

HABITAT

This is found almost always in patients with bad lung disease, usually when they’re in trouble.

CALL

“What should I do with this heart rate of 220?”

RESEMBLANCE TO OTHER ARRHYTHMIAS

This looks a whole lot like atrial fibrillation with a rapid ventricular response, the only difference being there are P waves (which admittedly may be hard to see) in front of all of the complexes; look closely where there are short pauses. Where the rate gets regular there may be runs of rapid supraventricular tachycardia. One needs to pore through the reams of printout to spot the irregular periods and detect the variable P waves.

CARE AND FEEDING

Mainly this is a question of what not to feed it. The overall rhythm will usually not slow down even with gallons of diltiazem, verapamil, and/or adenosine; all these agents will do is prevent (or, in the case of adenosine, briefly break) the sustained regular supraventricular tachycardias that are mixed in with all the other rapid, irregular rhythms. Digoxin will usually do nothing except cause toxicity, and is best avoided. Since these patients usually have bad lung disease with active wheezing in the midst of a serious exacerbation, β-blockers are probably best avoided too. Correct electrolyte abnormalities (especially low potassium), avoid toxicity from theophylline or too much β-agonists (from bronchodilators), and most importantly, optimize the underlying lung problems. You might consider using amiodarone, if you can pronounce it (remember it too has β-blocking effects which might be bad with bronchospasm). You can also give magnesium which doesn’t usually do anything but impresses the nurses. Because this is not atrial fibrillation and there is mechanical atrial activity, full anticoagulation is not indicated.

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