Cardiology: Arrhythmia Overview

Study Notes

Arrhythmia

Any change in the normal rate or rhythm of the heart.

Normal Heart Activity

Four key structures conduct electrical impulses through the heart muscle:
- Sinoatrial (SA) node, in the right atrium
- Atrioventricular (AV) node, between the right atria and ventricles
- Bundle of His (AV bundle) and bundle branches, carry current from the AV node to the ventricles
- Purkinje fibers, conduct current throughout the ventricular tissue
The SA node acts as the cardiac pacemaker, generating electrical impulses that are conducted through the atria to the ventricles, resulting in a "sinus rhythm".
The normal resting heart rate is approximately 70 beats per minute.
This is maintained by electrical impulses originating from the SA node.

Arrhythmia Etiology

Abnormal impulse formation or abnormal impulse conduction.
Caused by:
- Infarction, causing death of pacemaker cells or conducting tissue.
- Cardiac tissue disorder, e.g., fibrosis or rheumatic fever, disrupting the conduction network.
- Sympathetic or parasympathetic control changes, e.g., stress, anxiety, exercise, or smoking.
- Circulating drugs, e.g., antiarrhythmics or inotropes or other substances, e.g., caffeine, or alcohol.
- Electrolyte disturbances, e.g., hypothyroidism, hyperthyroidism, hyperkalemia and hypokalemia.
Patients with pre-existing cardiac disorders, like heart failure, hypertension, or a recent infarction are at greater risk of arrhythmias.

Description

This quiz covers the basics of arrhythmias, focusing on the normal heart activity and the role of various structures in conducting electrical impulses. Learn about the SA node, AV node, and the causes of abnormal heart rhythms. Test your understanding of how these factors affect heart health.