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…
Rhythm strip interpretation An electrocardiogram (ECG) complex represents the electrical events occurring in one cardiac cycle. A complex consists of five waveforms labeled with the letters P, Q, R, S,…
ECG basics One of the most valuable diagnostic tools available, an electrocardiogram (ECG) records the heart’s electrical activity as waveforms. By interpreting these waveforms accurately, you can identify rhythm disturbances,…
Cardiovascular assessment Performed correctly, cardiovascular assessment can help to identify and evaluate changes in the patient’s cardiac function. Complete cardiovascular assessment of a patient consists of obtaining an accurate, thorough…
Cardiac anatomy and physiology Knowing how to interpret an electrocardiogram (ECG) allows you to provide better patient care. For example, when caring for a patient with an arrhythmia or myocardial…
