1. Ventricular fibrillation. Ventricular fibrillation is a chaotic electrical activity with no discernible QRS complex. Immediate defibrillation is necessary to restore normal rhythm.
2. Ventricular tachycardia (VT). VT can be classified as sustained or nonsustained, with a generally accepted cutoff of 30 seconds. The rhythm may arise from the ventricular myocardium, the distal conduction system, or both. Causes of VT include ischemic heart disease, cardiomyopathy or heart failure, myocarditis, heart valve disease, and idiopathic VTStable patients are treated with amiodarone; patients with unstable VT are treated with synchronized cardioversion; and patients with pulseless VT need immediate defibrillation.
3. Torsades de pointes. Torsades de pointes is a specific type of polymorphic ventricular tachycardia associated with QTc prolongation and characterized by a gradual change in amplitude and twisting of the QRS complexes around the isoelectric line on the ECG. The rhythm may terminate spontaneously or may degenerate into ventricular fibrillation, which can be deadly. The most common causes of acquired QT prolongation are drugs, such as antiarrhythmic agents, antibiotics, antipsychotics, and antidepressants. Other causes include electrolyte imbalances, such as hypokalemia and hypomagnesemia, and genetic mutations. Treatment of torsades de pointes include magnesium sulfate or electrical cardioversion.
4. Atrial fibrillation. Atrial fibrillation is characterized by no discernible P waves and an irregularly irregular heart beats. It has strong associations with heart failure, coronary artery disease, valvular heart disease, diabetes mellitus, and hypertension. Common medications for managing atrial fibrillation include diltiazem, verapamil, digoxin, and amiodarone. Anticoagulant therapy may be necessary to prevent the formation of blood clots in the atria, which can lead to stroke.
5. Atrial flutter. Atrial flutter is a supraventricular arrhythmia that is usually about 150 beats per minute. It is characterized by a "saw-toothed" flutter appearance on the ECG that represents multiple P waves for each QRS complex. Adenosine or calcium channel blockers are commonly used to treat atrial flutter.
6. Paroxysmal supraventricular tachycardia. PSVT is characterized by episodes of rapid, regular heart rate that begins suddenly and ends suddenly. Treatment options include vagal maneuvers, adenosine, calcium channel blockers, and beta blockers.
7. First degree AV block. First-degree AV block is characterized by a prolonged PR interval greater than 0.20 seconds. It usually requires no treatment. Atropine may be indicated when symptomatic.
8. Second degree AV block type I (Wenckebach). Second-degree AV block type I is characterized by a progressive lengthening of the PR interval until a beat is dropped. It usually requires no treatment. Atropine may be indicated when symptomatic.
9. Second degree AV block Type II. Second-degree AV block type II is characterized by intermittent dropped beats with a constant PR interval. Symptomatic patients may require a pacemaker, bridged with dopamine or epinephrine infusion.
10. Third degree AV block (complete AV block). Third-degree AV block is characterized by no conduction between the atria and ventricles. Symptomatic patients may require a pacemaker, bridged with dopamine or epinephrine infusion.