EKG Rhythms
This image shows a Normal Sinus Rhythm, characterized by a heart rate of 60–100 bpm with evenly spaced and normal P, QRS, and T waveforms. It indicates proper electrical activity originating from the sinoatrial (SA) node, representing a healthy cardiac rhythm.
Normal Sinus Rhythm
60-100 bpm
all complexes normal and evenly spaced (P, QRS, T)

Key Terms
Normal Sinus Rhythm
60-100 bpm
all complexes normal and evenly spaced (P, QRS, T)
Sinus Arrest
- SA node doesn't fire
- notice absence of P-wave for a complete cycle (a missed cycle)
Sinus arrhythmia
all complexes normal but rhythmically irreg
- normal finding (esp in young pts) that has to do with breathing (rate: inhale-increase, exhale-dec...
Sinus Bradycardia
<60
normal sinus rhythm
Sinus Tachycardia
>100 (100-150)
normal sinus rhythm
Wandering atrial pacemaker
Hint: try never to pick this
- impulse originate from varying points in atria
- variation in P wave contour, PR-I, PP-I and thus RR-I
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| Term | Definition |
|---|---|
Normal Sinus Rhythm | 60-100 bpm |
Sinus Arrest | - SA node doesn't fire |
Sinus arrhythmia | all complexes normal but rhythmically irreg |
Sinus Bradycardia | <60 |
Sinus Tachycardia | >100 (100-150) |
Wandering atrial pacemaker | Hint: try never to pick this |
P wave vs T wave | P generally smaller than T |
MAT (multifocal atrial tachy) | - impulse originates at diff places in atria so P waves diff and intervals might not be consistent |
Atrial Fibrillation | A: 350-450 (atria quivering) |
Atrial Flutter | A: 250-350 |
Junctional Escape beats | retrograde atrial depolarization |
Junctional rhythm | 40-60 Regular! |
Junctional Tachycardia | >60 bpm (ms. K; 150-250) |
Premature junctional contractions (PJC) | - premature slightly widened QRS |
Premature atrial contractions (PAC's) | - originates suddenly in irritable atrial foci |
Supraventricular Tachycardia (SVT) | 150-250 "sudden rapid heart rate" |
First-degree AV block | - PRI >5 boxes/.20 sec |
Second-degree block: Mobitz Type I Wenckebach) | "walk it back" |
Second-degree AV block: Mobitz Type II | - normal PRI then sudden drop of QRS |
Third-degree AV block (complete block) | rate around 40's |
Asystole | - dead |
Premature ventricular contractions (PVC's) | Wide QRS |
Idioventricular rhythm | <40 |
Accelerated idioventricular rhythm (AIVR) | 40-120 |
Ventricular tachycardia | 150-250 (>120 from onysko) |
Ventricular Flutter | 250-350 |
Tosades de Pointes | Flutter 250-350 |
Ventricular Fibrillation | 350-450 |
R atrial hypertrophy | tall P waves! (in lead II, III, and aVF) |
L atrial hypertrophy | I --> wide P wave (biphasic) |
R ventricular hypertrophy (RVH) | - tall R wave in V1 (inverted T here too) |
L ventricular hypertophy (LVH) | V1 --> deep/long S wave |
BBB | - Wide QRS >3 box |
R Bundle Branch Block | - wide QRS >3 boxes (0.12) |
L Bundle Branch Block | - wide QRS >3 boxes (0.12) |
Myocardial Infarction (MI) | Ischemia: inverted Twave |
Ischemia | - T wave inversion |
Injury | ST segment elevation (a sign of acute injury going on presently) (look for sad face) |
Necrosis | significant Q waves |
anterior wall | V1, V2, V3, V4 |
Anteroseptal region | V1, V2 |
Inferior wall | II, III, aVF |
Lateral wall | I, aVL and V5, V6 |
Posterior wall | since no post lead look in V1 for unusually large R wave |
Angina pectoris | Angina pectoris is chest pain caused by reduced blood flow to the heart muscle, typically triggered by physical activity or stress. |
Unstable angina | Unstable angina is chest pain due to reduced blood flow to the heart that occurs at rest or with minimal exertion and is a medical emergency. |
Digitalis Effect | - shortened QT interval |
Hypercalcemia | Short/absent QT segment |
Hypocalcemia | (not healthy (not taking vit like Ca++) so look like a hipo which is large -> long QT) |
Hyperkalemia | tall, peaked and narrow T |
Hypokalemia | - flat T present |
Lown-Ganong-Levine Syndrome | AV node by passed, so short PRI |
Pacemakers | pacemaker spike (may be small; sometimes missed) |
Pericarditis | ST segment elevated in ALL leads |
Pulmonary embolus | (S1 Q3 T3) |
Wolf-Parkinsons-White | - P wave is immediately followed by short delta wave |
Axis | Refers to the direction of movement of depolarization |
Axis pic | |
Wide QRS | Vtach, PVC, 3o AV block, BBB |
Rate 40's | 3o AV block, 2o AV block type II, or ventricular rhythm |