Disorders affecting 12-lead ECGs A 12-lead electrocardiogram (ECG) is a key tool in diagnosing and evaluating certain disorders, such as angina, Prinzmetal’s angina, myocardial infarction (MI), pericarditis, left ventricular hypertrophy…
Electrocardiogram analysis After obtaining an electrocardiogram (ECG), you’ll want to read and interpret the findings. Becoming comfortable with ECG analysis will allow you to detect subtle, and sometimes dangerous, changes…
Basic 12-lead electrocardiography The 12-lead electrocardiogram (ECG) is a diagnostic test that helps identify pathologic conditions, especially ischemia and acute myocardial infarction (MI). It provides a more complete view of…
Nonpharmacologic treatment Nonpharmacologic treatments for arrhythmias—including pacemakers, implantable cardioverter-defibrillators (ICDs), and radiofrequency ablation—produce distinctive electrocardiogram (ECG) tracings. By understanding how these devices work, and the ECG changes they produce, you’ll…
Electrolyte imbalances and drugs Patients with electrolyte imbalances—such as hyperkalemia, hypokalemia, hypercalcemia, and hypocalcemia—frequently show distinctive rhythm changes on electrocardiograms (ECGs). Likewise, patients taking such drugs as digoxin (Lanoxin) may…
Atrioventricular blocks Atrioventricular (AV) heart block refers to an interruption or delay in the conduction of electrical impulses between the atria and the ventricles. The block can occur at the…
Ventricular arrhythmias Ventricular arrhythmias originate in the ventricles below the bifurcation of the bundle of His. These arrhythmias occur when electrical impulses depolarize the myocardium using a different pathway from…
Atrial arrhythmias Atrial arrhythmias, the most common cardiac rhythm disturbances, result from impulses originating in the atrial tissue in areas outside the sinoatrial (SA) node. These arrhythmias can affect ventricular…
Junctional arrhythmias Junctional arrhythmias originate in the atrioventricular (AV) junction—the area in and around the AV node and the bundle of His. The specialized pacemaker cells in the AV junction…
Sinus node arrhythmias When the heart functions normally, the sinoatrial (SA) node (also called the sinus node), acts as the primary pacemaker. The sinus node assumes this role because its…
