CRAT Cheat Sheet 2026

The 30 highest-yield CRAT facts, distilled from real exam questions. Print it, save it as a PDF, or study it here — free, no sign-up.

1. If limb leads show reversed arm electrode placement (right and left arm switched), which lead will appear inverted compared to a correct recording? → Lead I
2. Wolff-Parkinson-White (WPW) syndrome produces which classic triad of ECG findings? → Short PR interval (< 120 ms), delta wave (slurred QRS upstroke), and wide QRS complex
3. Improper placement of the V4 electrode (placed too high, at the 4th ICS instead of 5th) would most likely affect which finding? → R wave progression and ST segment changes in the precordial leads
4. Baseline wander on an ECG is most commonly caused by which factor? → Patient breathing or movement causing electrode-skin interface changes
5. A pacemaker spike followed by a wide, abnormal QRS complex indicates what type of pacing? → Ventricular pacing with successful capture
6. Which medication is a common pharmacological cause of AV block? → Digoxin
7. Which structure is the primary pacemaker of the heart under normal conditions? → Sinoatrial (SA) node
8. The combination of right bundle branch block (RBBB) and left anterior fascicular block (LAFB) is called: → Bifascicular block
9. Which underlying condition is the MOST common cause of left bundle branch block? → Hypertensive heart disease or coronary artery disease
10. AV dissociation that is NOT due to complete heart block can occur in which situation? → Accelerated junctional rhythm that exceeds the sinus rate
11. The refractory period of the AV node serves which primary function? → Limiting ventricular rate during rapid atrial arrhythmias
12. Sinoatrial (SA) exit block type II is distinguished from sinus arrest by which feature? → SA exit block produces pauses that are exact multiples of the basic P-P cycle length
13. In a 12-lead ECG, which leads are considered the inferior leads? → II, III, and aVF
14. What is the intrinsic firing rate of the AV node if it serves as the escape pacemaker? → 40-60 bpm
15. The QT interval is measured from: → Start of Q wave to end of T wave
16. An ECG shows a QRS of 0.14 sec with broad notched R waves in I, aVL, V5–V6 and a broad QS in V1. What is the most likely diagnosis? → Left bundle branch block
17. A patient is experiencing a blockage in the right coronary artery (RCA). Which of the following structures is most likely to be affected? → SA node and right ventricle
18. Which of the following correctly describes an INCOMPLETE right bundle branch block? → QRS 0.10–0.11 sec with rSR' in V1
19. Paroxysmal supraventricular tachycardia (PSVT) most commonly has which ventricular rate range? → 150-250 bpm
20. A regular rhythm with a narrow QRS complex with no notes P wave and rates between 40-6- bpm is known as: → Junctional escape rhythm
21. Which cells in the heart have the property of automaticity, meaning they can spontaneously depolarize? → Pacemaker cells in the SA node, AV node, and His-Purkinje system
22. Which waveform on the ECG represents ventricular repolarization? → T wave
23. What does a delta wave at the onset of the QRS complex suggest? → Pre-excitation syndrome (e.g., WPW)
24. Atropine is administered in cardiac emergencies primarily to treat: → Symptomatic bradycardia
25. Beta-blockers used as antiarrhythmics belong to which Vaughan Williams class? → Class II
26. Which ion primarily responsible for Phase 3 (rapid repolarization) of the ventricular action potential? → Potassium efflux through IKr and IKs channels
27. Which characteristic of the QRS complex in complete heart block provides a clue about the location of the escape pacemaker? → Narrow QRS suggests a junctional escape; wide QRS suggests a ventricular escape
28. The T wave on the ECG represents which electrophysiological event? → Ventricular repolarization
29. During continuous cardiac monitoring, an alarm is triggered for a critical low heart rate. What should the monitor technician do first? → Assess the patient clinically and notify the nurse or clinician immediately
30. The NBG (NASPE/BPEG) pacemaker code uses letters to describe pacemaker function. In a VVI pacemaker, what does the second 'V' indicate? → The ventricle is the sensed chamber