Atrial Tachycardia

Slows conduction through AV node

lInhibits adenylyl cyclase, thus reduces cAMP, thus outward K flux, thus hyperpolarization

T ½ < 10 seconds

Side effects (>10%)

Cardiovascular: Transient new arrhythmia (eg, atrial premature contractions, atrial fibrillation, PVCs) after cardioversion (55%)

Facial flushing (18% to 44%), Headache (2% to 18%), dizzinesss (2% to 12%)

GI discomfort (13%), Discomfort of neck, throat, jaw (<1 15="" span="" to="">

Chest pressure/discomfort (7% to 40%), dyspnea (12% to 28%)

Caffeine and Theophylline antagonize receptors

Carbamazepine, Dipyridamole potentiate

Very Careful with patients on: Verapamil or Dilt, especially IV

Be aware: Severe Asthma

Careful in elderly

 

Atrial Tachycardia --  Rapid dysrhythmia from non-sinus focus above AV node

Causes: Electrolytes, acid-base, drug toxicity, fever, hypoxia, hyperthyroid

Digitalis intoxication

Correct hypokalemia, Give Digibind

Treatment: 

Correct underlying disturbance

Beta blocker or Ca channel blocker

Mg (2-4 g IV)

Adenosine occasionally terminates

If due to Sinus node re-entry or triggered activity

lElectrical treatment rarely needed

l50-100 J if unstable

lOverdrive transvenous atrial pacing

 

 

PAT efficacy: depends on which etiology

lAutomatic (transient slowing)

lRe-entrant  in non-sinus atrial tissue (no effect, as in flutter)

lRe-entrant in sinus node (terminates)

lTriggered – it works

lAtrial myocytes

lShortens atrial action potential duration

lDoes not hyperpolarize

lNo effect on intra-atrial re-entry

lSinus node

lHyperpolarization

lStops sinus node re-entry PAT

lTemporarily inhibits sinus rhythm

lShortens atrial action potential duration

lAnti-adrenergic--Inhibition of cAMP--Stops cAMP-triggered activity

lJust try it

 

 

Adenosine terminated sinus node reentrant tachycardia in 6 of 6 patients and terminated atrial tachycardia    

due to triggered activity in the 1 patient in whom it was identified. Adenosine transiently suppressed 

automatic atrial tachycardia in 7 of 7 patients and had no effect in 13 patients with intra-atrial reentrant 

tachycardia, including 8 patients with atrial flutter. 

Mechanism-specific effects of adenosine on atrial tachycardia

ED Engelstein, N Lippman, KM Stein and BB Lerman.  Circulation, Vol 89, 2645-2654

BACKGROUND: Recent reports suggest that adenosine, in addition to terminating supraventricular tachycardia involving the atrioventricular (AV) node, may have antiarrhythmic effects on atrial tachycardia. The electrophysiological effects of adenosine on supraventricular tissue include shortening of action potential duration in atrial myocytes mediated by the potassium current, IKACh,Ado; shortening of action potential duration and hyperpolarization in sinus node cells; and anti- adrenergic electrophysiological effects resulting from inhibition of adenylyl cyclase. We therefore hypothesized that the response of atrial tachycardia to adenosine would be mechanism specific, with termination of atrial tachycardia due to sinus node reentry or cAMP-mediated triggered activity, transient suppression of automatic atrial tachycardia, and an absence of antiarrhythmic effect on tachycardia due to intraatrial reentry. METHODS AND RESULTS: Adenosine (mean +/- SD, 143 +/- 54 micrograms/kg IV) was administered to 27 patients (55 +/- 19 years) in atrial tachycardia whose mechanism was confirmed by electrophysiological study. Adenosine terminated sinus node reentrant tachycardia in 6 of 6 patients and terminated atrial tachycardia due to triggered activity in the 1 patient in whom it was identified. Adenosine transiently suppressed automatic atrial tachycardia in 7 of 7 patients and had no effect in 13 patients with intra-atrial reentrant tachycardia, including 8 patients with atrial flutter. CONCLUSIONS: These findings demonstrate that adenosine's effects on atrial tachycardia are mechanism specific and can be used to differentiate between reentrant tachycardia confined to the region of the sinus node or atria and between nonreentrant atrial tachycardia due to either triggered activity or automaticity.