EKG Fundamentals

Electrocardiography (EKG/ECG) captures the heart's electrical activity. Electrodes on the skin detect impulses, revealing heart rate, rhythm, and conditions like arrhythmias or myocardial infarction. It's a non-invasive, painless procedure with immediate results.

The heart's electrical signal initiates in the SA node, travels to the AV node, then to the bundle branches, and finally the Purkinje fibers. This precise pathway ensures coordinated contractions, pumping blood effectively.

An EKG has distinct components: P wave (atrial depolarization), QRS complex (ventricular depolarization), and T wave (ventricular repolarization). Their shapes, sizes, and intervals diagnose cardiac abnormalities.

The PR interval indicates AV node delay; the QT interval reflects total ventricular activity. Abnormal intervals can signal blockages, electrolyte imbalances, or drug effects. These readings guide medical interventions.

EKGs can distinguish between types of myocardial infarctions. ST-elevation (STEMI) indicates a full blockage of a coronary artery. Non-ST-elevation (NSTEMI) suggests partial blockages. Treatment strategies differ accordingly.

EKGs may also reveal non-cardiac conditions such as electrolyte imbalances, pulmonary embolisms or even hypothermia. T wave inversions or U waves might indicate underlying issues not directly related to the heart itself.

The first human EKG was recorded in 1887. Since then, technology has evolved from bulky, immobile machines to portable devices like Holter monitors and even smartphone attachments, increasing accessibility and continuous monitoring.