Dr. Christopher Carrubba and Dr. Brian Radvansky contributed to this article.
Let’s face it—some things just have to be memorized. While the USMLE is full of conceptual material that apt students can reason their way through, it is also comprised of material requiring brute force memorization for mastery.
Fortunately, mnemonics can be an anxious, overworked medical student’s best friend. And, better yet, they can help you grab a lot of points on your USMLE. Utilize these tricks and watch your scores climb higher than before.
Topic: Class I Antiarrhythmics
Mnemonic: Double Quarter Pounder, Lettuce Mayo, Fries Please
Pharmacology is one of those subjects that you just have to memorize. Mechanisms of action, side effects, and common uses of medications are high yield material for the USMLE that cannot be answered any other way. While there are hundreds of drugs that are fair game on the exam, learning their properties can often be made easier by lumping drugs into medication classes. Sometimes, this can be very easy. Whoever decided to name all of the statins, ‘______statin’, clearly had medical students in mind. Other times, we are not that fortunate. Alas, the bane of antiarrhythmics.
If you are scared of these drugs, you’re not alone – many medical students have found themselves panicking as none of the antiarrhythmics sound alike, there are four separate classes, and each has a seemingly complicated mechanism of action. Fortunately, the following tricks work wonders.
• Class I Antiarrhythmics are the sodium channel blockers, and these are further classified as Class IA, IB, and IC. To remember these, try Double Quarter Pounder, Lettuce Mayo, Fries Please.
Broken down, it looks like this:
1. Class IA = Disopyramide, Quinidine, and Procainamide
2. Class IB = Lidocaine and Mexiletine
3. Class IC = Flecainide and Propafenone
Eesh, 7 drugs, and we are only in class one. Let us see if we can smooth things out a bit. Memorizing which classes have positive and negative effects on the effective refractory period/action potential duration and level of sodium channel blockade is certainly not high yield. They are all factoids which likely won’t help you on the test outside of a singular question, and unless you find yourself in an electrophysiology fellowship, probably won’t be too much use either.
Also, as Step 1 becomes pass/fail, and fighting for scientific minutiae becomes less important, the Step 2 ethos of clinical application becomes all the more valuable. Ergo, let us approach this from an indication standpoint.
It’s likely the anesthesiologist in me talking, but your most important drug here is lidocaine. It has indications as a local anesthetic, an analgesic, and as a rhythm stabilizer. It can be deployed for VENTRICULAR arrhythmias like ventricular tachycardia and ventricular fibrillation.
Probably the next most important on this list is procainamide, which is used for Wolff-Parkinson-White syndrome (the pre-excitation syndrome with delta-waves, a USMLE read-this-EKG favorite), and ventricular arrhythmias that don’t respond to other treatments.
It won’t be too often that you come across the other drugs on this list. Remember their category, but don’t overstudy the finer points of all of them.
Topic: Class II Antiarrhythmics
• Class II Antiarrhythmics are the beta blockers. Remember, these all end in ___lol (metoprolol, propranolol, carvedilol, etc.)
Thank goodness there’s some logic in this naming system! Beta-blockers are so common in clinical practice; you will definitely come across them with great frequency. They are indicated during myocardial infarctions to reduce myocardial oxygen demand (as long as your patient is not hypotensive). Heart failure patients also benefit from their administration. They can be used for supraventricular tachycardias (tachycardias that originate above/before the ventricles). These include paroxysmal SVT, atrial fibrillation with rapid ventricular response, and sinus tachycardia.
While we’re here, let’s touch upon beta-blocker side effects and contraindications. Side effects include [orthostatic] hypotension, fatigue, heart block, sexual dysfunction, and possible bronchospasm. For the contraindications, remember the mnemonic ABCD.
A: Asthma (beta-2 agonism can narrow airways
B: Block (heart block should not be further blocked!)
C: (C)HF - Tricky one. While utilized in the chronic management of heart failure, patients with acute decreases in contractility should not be beta-blocked.
D: Diabetes - More theoretical. Beta-blockade can shadow a hypoglycemic event.
Topic: Class III Antiarrhythmics
Class III Antiarrhythmics are the potassium channel blockers, which can be memorized with the mnemonic AIDS.
Here it is broken down:
1. A = amiodarone
2. I = ibutilide
3. D = dofetilide
4. S = Sotalol
Of these, your golden child is amiodarone. It is used for refractory VT and VF, and can be an acute and chronic solution to atrial fibrillation.
It’s useful to remember that side effects of amiodarone can affect your “_____ function tests.” Liver, thyroid, and pulmonary.
Topic: Class IV Antiarrhythmics
Class IV Antiarrhythmics are the calcium channel blockers verapamil and diltiazem.
When it comes to calcium channel blockers, one of my favorites was memorizing them in two classes. You have your centrally acting ones that focus on heart rhythm (non-dihydropyridines), as above. Members of the other class (dihydropyridines) all end in -dipine (e.g., nicardipine, amlodipine).
Dipines act Distally through vasoDilation and can cause eDema.
There you have it—an easier way of memorizing this complicated topic.
Here are some additional USMLE mnemonics!