-Asthma with ongoing wheezing
                                   -AVB 2nd or 3rd degree
(without PM)
-SSS (without PM)
-SBP < 90 mmHg
                                   -Recent use of Dipyridamole
or dipyridamole containing drigs (Aggrenox)
-Methyl Xanthines (aminophylline, caffeine, theobromine) block the effect
                                   of adenosine and should be held at least 12 hours
-Hypersensitivity to Adenosine
                                   -Unstable acute MI or ACS
                                   -Profound Bradycardia (< 40 bpm)

                                    -Hypotension (SBP<80 mmHg)
                                    -Symptomatic, persistent 2nd or 3rd AVB
                                    -Chest pain with >2 mm ST depressions
                                    -Signs of poor perfusion (pallor, cyanosis, cold skin)
                                    -Patient's request
Mechanism of action induces direct arteriolar vasodilation through specific activation of the
A2A receptor which results in a 3.5-4 fold increase in myocardial blood flow. There is minimal or no
increase in rate-pressure product (= myocardial O2 demand). However, in a small number of patient true
ischemia might be induced because of
coronary steal phenomenon.

Side Effects
-A1 receptor activation: AV Block (7.6% low grade - 4% second degree AVB - <1% CHB)
-A2b receptor activation: peripheral vasodilation
-A2b and A3 receptors activation: Bronchospasm
-Minor Side effects (80%): Flushing (35-40%), Chest Pain (25-30%), Dyspnea (20%), Dizziness (7%),
Nausea (5%), symptomatic hypotension (5%). Chest pain is non specific and not indicative of the
presence of CAD
-ST Depression > 1mm, 5-7%, usually indicative of CAD
-Adenosine has a very short half life (<10 seconds) and aminophylline is rarely required

Dosage 140 mcg/Kg/min continuous infusion over a 6 minute period (or a shorter 4 minute)
The tracer is given at min 2-4 depending on duration of infusion and
the infusion should be continued
at least 2 minute after tracer injection.

Can be started at a lower dose (70-100 mcg/kg/min), if this dose is tolerated for 1 minute, infusion
rate is increased to 140 mcg/kg/min and continued for 4 minutes. The radiotracer is injected 1
minute after starting the 140 infusion.

1.7 mph, 0% grade exercise decreases Adenosine side effects and hypotension
Not recommended for patients with LBBB
140 mcg/kg/min - 6' infusion
followed by NS flush
1.7 mph, 0% grade exercise