Adenosine - CR Flashcards
What is the primary mechanism of action of adenosine?
To slow AV conduction aiming to terminate re-entry circuit activity.
Which receptors does adenosine bind to in cardiac tissues?
Ai receptors.
What effect does adenosine have on potassium channels?
It opens potassium channels, which hyperpolarizes the cell.
How does adenosine affect CAMP levels in cardiac tissues?
It decreases CAMP levels.
What is the effect of decreased CAMP on calcium channels?
It inhibits particular calcium channels and decreases calcium entry into the cell.
What is the effect of adenosine on pacemaker cells located in the sinoatrial node?
It inhibits the pacemaker current, decreasing the slope of phase 4 of the action potential.
What is the result of decreased slope of phase 4 in pacemaker cells?
Decreased spontaneous firing rate (negative chronotrope).
What is the initial bolus dose of adenosine administered by Ambulance Victoria?
6mg.
What is the maximum dose of adenosine that can be administered if no reversion occurs?
12mg and subsequent 12mg.
In which conditions is adenosine contraindicated?
Second and third degree AV blocks.
What serious outcome can occur if adenosine is given to patients with atrial fibrillation or atrial flutter?
Serious rhythm degeneration and even death.
What potential effect can adenosine have on atrial flutter with 2:1 conduction?
Convert it to 1:1 conduction with a heart rate of 300.
How does adenosine affect antegrade conduction through the AV node?
It slows or blocks antegrade conduction.
What is a dangerous effect of adenosine in patients with atrial fibrillation and bypass tracts?
Patients may degenerate into rapid atrial fibrillation with rates at 250 or greater.
What is the contraindication listed by Ambulance Victoria regarding ventricular arrhythmias?
Ventricular arrhythmias are listed as a contraindication.
Can adenosine be helpful diagnostically in certain cases?
Yes, to differentiate undifferentiated wide complex tachycardias.
True or False: Adenosine is safe and useful in the hospital setting for diagnosing wide complex tachycardias.
True.
