The overall goal of the Acetylcholine Test is to assess whether a patient suffers from a coronary vasomotor disorder such as an epicardial or coronary microvascular spasm. The acetylcholine test is helpful for detecting a coronary vasomotor disorder. Especially in patients with angina pectoris and unobstructed coronary arteries.
The wonderful thing about the acetylcholine test is that you can perform it immediately after diagnostic angiography. And it doesn't cost a lot of money and it doesn't take a lot of time. Before beginning the procedure, mix 20 milligrams of acetylcholine with two milliliters of the acetylcholine solvent.
Then mix two milliliters of the resulting acetylcholine solution with 98 milliliters of 0.9%sodium chloride. Next add nine milliliters of this 0.2 milligram per milliliter acetylcholine solution with 91 milliliters of sodium chloride to achieve an 18 microgram per milliliter aceteylcholine solution and label the container High"Fill a 50 milliliter profusion syringe with 40 milliliters of the 18 microgram per milliliter acetylcholine solution. Then transfer eight milliliters of the acetylcholine solution from the High"syringe into a second 50 milliliter profusion syringe and add 32 milliliters of sodium chloride into the second syringe to achieve a 3.6 microgram per milliliter acetylcholine dose.
Label this syringe Medium"Transfer four milliliters of the medium concentration of acetylcholine into a third 50 milliliter profusion syringe. Add 36 milliliters of sodium chloride to the third syringe to obtain a 0.36 microgram per milliliter acetylcholine dose. And label this syringe Low"After injecting local anesthesia in proximity to the patient's right radial artery, confirm that the region is numb.
Then place a catheter according to standard protocols. After visually excluding any epicardial stenosis, inject six liters of the two microgram Low"acetylcholine dose into the left coronary artery over the course of 20 seconds while monitoring ECG and the patient's symptoms. Then inject 10 milliliters of contrast agent manually via a contrast syringe into the catheter to visualize the coronary arteries.
After one minute inject six milliliters of the 20 microgram Medium"acetylcholine dose into the left coronary artery as performed for the low dose. Follow this by injecting 10 milliliters of contrast agent. After another minute, repeat the injection with 5.5 milliliters of the 100 microgram High"acetylcholine dose.
Again follow the acetylcholine injection with 10 milliliters of contrast agent. Most patients will develop symptoms, ECG changes, or an epicardial spasm at this dose. If bradycardia is observed on the ECG, reduce the speed of the injection and observe the ECG carefully.
If no spasm has occurred after one minute, administer 11 milliliters of the 200 microgram High"acetylcholine dose. Followed by 10 milliliters of contrast agent. If no abnormal findings are observed, inject 4.5 milliliters of the 80 microgram acetylcholine dose into the right coronary artery as just demonstrated followed by 10 milliliters of contrast agent.
Then inject 200 microgram of intracoronary nitroglycerin into each tested artery and image the vessel after one minute as just demonstrated to document the reversion of the spasm. Epicardial coronary spasm is diagnosed when an epicardial vasoconstriction greater than or equal to 90%compared to the relaxed state after nitroglycerin administration together with ischemic ECG shifts and a reproduction of the patient's symptoms are observed. A microvascular spasm is diagnosed in the case of a reproduction of the patient's symptoms with ischemic ECG shifts, usually ST segment depression during the acetylcholine test without any epicardial vasoconstriction greater than or equal to 90%Remember that the interpretation of the acetylcholine test is based on patient's symptoms, ECG shifts, and the angiographic appearance of the coronary arteries during the test.
I hope this video will encourage interventional cardiologists to incorporate the acetylcholine test into their diagnostic armamentarium because the result of this test informs about the patient's symptoms, the cause of the patient's symptoms and it helps to select the appropriate treatment.
