EKG Interpretation Cheat Sheet & Heart Arrhythmias Guide (2020 Update) - Free Printable

- Second-degree AV block Mobitz I (Wenckebach): Atrial rhythm regular, ventricular rhythm irregular, atrial rate exceeds ventricular rate, PR interval progressively lengthens until QRS complex disappears, PR interval shorter after dropped beat. Causes: severe coronary artery disease, anterior wall MI, acute myocarditis, digoxin toxicity. Treatment: atropine, epinephrine, dopamine for symptomatic bradycardia; temporary or permanent pacemaker for symptomatic bradycardia; discontinue digoxin if appropriate.
- Third-degree AV block (complete heart block): Atrial rhythm regular, ventricular rhythm regular and slower than atrial rate, no relation between P waves and QRS complexes, no constant PR interval, QRS interval normal (nodal pacemaker) or wide and bizarre (ventricular pacemaker). Causes: inferior or anterior wall MI, congenital abnormality, rheumatic fever. Treatment: atropine, epinephrine, dopamine for symptomatic bradycardia; temporary or permanent pacemaker for symptomatic bradycardia.
- Premature ventricular contraction (PVC): Atrial rhythm regular, ventricular rhythm irregular, QRS complex premature usually followed by complete compensatory pause, QRS complexes wide and distorted (>0.14 sec), premature QRS complexes occurring singly, in pairs, or in threes alternating with normal beats, focus from one or more sites, ominous when clustered, multifocal, with R wave on T pattern. Causes: heart failure, old or acute myocardial ischemia, infarction, contusion, myocardial irritation by ventricular catheters, hypercapnia, hypokalemia, hypocalcemia, drug toxicity (cardiac glycosides, aminophylline, tricyclic antidepressants, beta-adrenergic), caffeine, tobacco, alcohol, psychological stress, anxiety, pain. Treatment: if warranted, procainamide, lidocaine, or amiodarone IV; treat underlying cause; discontinue drug causing toxicity; potassium chloride IV if PVC induced by hypokalemia; magnesium sulfate IV if PVC induced by hypomagnesemia.
- Ventricular Tachycardia: Ventricular rate 140–220 bpm, regular or irregular, QRS complexes wide, bizarre, independent of P waves, P waves not discernible, may start and stop suddenly. Causes: myocardial ischemia, infarction, aneurysm, coronary artery disease, rheumatic heart disease, mitral valve prolapse, heart failure, cardiomyopathy, ventricular catheters, hypokalemia, hypercalcemia, pulmonary embolism, digoxin, procainamide, epinephrine, quinidine toxicity, anxiety. Treatment: if pulseless, initiate CPR, follow ACLS protocol for defibrillation; if with pulse and hemodynamically stable, follow ACLS protocol for amiodarone; if ineffective, initiate synchronized cardioversion.
- Ventricular Fibrillation: Ventricular rhythm and rate rapid and chaotic, QRS complexes wide and irregular, no visible P waves. Causes: myocardial ischemia or infarction, R-on-T phenomenon, untreated ventricular tachycardia, hypokalemia, hyperkalemia, hypercalcemia, alkalosis, electric shock, hypothermia, digoxin, epinephrine, or quinidine toxicity. Treatment: if pulseless, start CPR, follow ACLS protocol for defibrillation, ET intubation, administer epinephrine or vasopressin, lidocaine, or amiodarone; if ineffective, consider magnesium sulfate.
- Asystole: No atrial or ventricular rate or rhythm, no discernible P waves, QRS complexes, or T waves. Causes: myocardial ischemia or infarction, aortic valve disease, heart failure, hypoxemia, hypokalemia, severe acidosis, electric shock, ventricular arrhythmias, AV block, pulmonary embolism, heart rupture, cardiac tamponade, hyperkalemia, electromechanical dissociation, cocaine overdose. Treatment: start CPR.