Will adenosine be effective for treating slow flow due to coronary vasospasm during cardiac catheterization?

Adenosine for Slow Flow from Coronary Vasospasm During Catheterization

No, adenosine is not the appropriate treatment for slow flow caused by coronary vasospasm during catheterization—you should use intracoronary nitroglycerin instead, as adenosine can paradoxically worsen vasospasm and is primarily a microvascular dilator with minimal effect on epicardial conduit arteries. 1

Why Adenosine is Inappropriate for Vasospasm

Mechanism Mismatch

• Adenosine causes vasodilation primarily of the coronary microcirculation with minimal effect on epicardial conduit arteries, acting through A2 receptors to increase cytosolic cyclic adenosine monophosphate. 1
• Vasospasm occurs in the epicardial coronary arteries, not the microcirculation, making adenosine mechanistically the wrong choice. 1

Risk of Paradoxical Worsening

• Adenosine can actually induce coronary artery spasm as a rare but serious complication, with documented cases of ST-segment elevation and chest pain requiring nitroglycerin reversal. 2
• The American Heart Association acknowledges that coronary spasm is a rare but serious complication of adenosine administration. 1

Correct Treatment Approach

First-Line: Intracoronary Nitroglycerin

• The American Heart Association recommends administering intracoronary isosorbide dinitrate or nitroglycerin at least 2 minutes before FFR measurement to abolish epicardial vasoconstrictor tone. 1
• The European Society of Cardiology recommends intracoronary nitroglycerin to reverse vasospastic effects and allow assessment of endothelium-independent epicardial coronary vasodilation. 3
• Nitroglycerin should be administered immediately if coronary vasospasm is induced during catheterization. 3

When Adenosine IS Appropriate

• Adenosine is indicated for treating no-reflow phenomenon (microvascular dysfunction), not epicardial vasospasm—these are distinct pathophysiologic entities. 4, 5
• For resistant no-reflow, very high doses of adenosine (up to 1 mg) administered distally via balloon catheter have been successful. 5

Critical Clinical Distinction

The key is distinguishing between:

• Epicardial vasospasm → Treat with nitroglycerin 1, 3
• Microvascular no-reflow → Treat with adenosine 4, 5

Monitoring Requirements

• Continuous ECG monitoring, Doppler flow monitoring, and symptom assessment should occur throughout any intervention for slow flow. 3
• If adenosine were mistakenly given and vasospasm worsens, immediate administration of sublingual or intracoronary nitroglycerin is required. 2

Common Pitfall to Avoid

Do not confuse slow flow from epicardial vasospasm with microvascular no-reflow—they require opposite treatment strategies, and using adenosine for vasospasm may worsen the clinical situation by potentially inducing further spasm while failing to address the epicardial constriction. 1, 2