Disorders of the Cardiovascular System: Arrhythmia's

From one student to another I have designed these study guides to help other student nurses during their school term. During my training I have gained valuable information that I processed into my own notes to help study for tests and the boards at the end of my training. I share with you this information to help the student nurse or any student in a medical related setting.

If you haven't already read our article on the Cardiac Anatomy and Physiology we suggest you read it to have a better understanding of how the heart is made up and how the heart works. One question many people ask is how the heart beats? The heart beats by electrical impulses, these electrical impulses stimulate the heart muscles to contract. This is called the conduction system, the conduction system is made up of fibers and nodes that branch through the myocardium.

To understand various disorders of the heart one must have an understanding of different aspects of the heart for instance the SA Node is the master node of the heart and also called the pacemaker of the heart it is located in the right atrium while the AV node accepts the impulses from the SA node to continue the impulse the AV node is considered the backup pacemaker but is not as effective as the SA node.

Arrhythmias - Arrhythmias are irregularities in the conduction system and can be caused by medications, electrolyte imbalances, irritability of the heart, and other medical conditions to name a few causes.

Arrhythmias are basically the interruption of the normal pattern of heart beating, it can either be an increase in beats per minute or a decrease in beats per minute. Below is a common list of types of disorders that deal with the normal beats per minute.

Sinus Bradycardia is rate less than 60 beats per minute, complex's are regular and impulses originate in the SA node.

Sinus Tachycardia is a rate of 101 to 150, complex's are regular and impulses also originate in the SA node.

Supraventricular Tachycardia is when the heart rate is above 150, impulses originate in the atria and patient has a decrease in cardiac output this is not tolerated for long periods of time.

Premature Atrial Contractions (PACs) is when the atrium beats prematurely, ventricles beat with it but the P complexes is premature and looks a little different on a reading. This is experienced by everyone at some point and the rate will be irregular this is mostly a benign disorder but can be seen preceding atrial fib.

Atrial Fibrillation is when the atrial rate is higher than the ventricular rate, not all the P waves are conducted and the patient may have a decrease in cardiac output. The causes of atrial fibrillation are trauma, heart irritability, meds, or an unknown cause.

Sources:
Mosby (2005) Foundations and Adult Health Nursing (5th ed.) Missouri: Christensen & Kockrow.