Good Samaritan Hospital
Heart & Vascular Center
375 Dixmyth Ave.
Cincinnati, Ohio 45220
(513) 862-3588
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What is Arrhythmia?
An arrhythmia – or irregular heartbeat – is a heart rate that is faster or slower than the average heart rate. It is a disturbance in the normal beating pattern of the heart. To understand arrhythmia and its types, however, one must understand the heart and how it beats.
Heart Has Four Chambers
The heart is made up of four chambers that hold and pump blood. (See image) The top two chambers are the right atrium (1) and left atrium (3). The atria collect blood returning to the heart from the veins. The atria then release the blood into the bottom chambers through valves. Heart valves act as one-way doors to separate the chambers and keep the blood moving forward.
The two bottom chambers are called the right ventricle (6) and the left ventricle (7). A wall, the septum, separates the two right chambers from the two left chambers. Because of this, you may hear your heart described as two pumps, the “right heart” and the “left heart.” When the ventricles contract, they force blood out of the heart to different parts of the body.
 Click image for larger version |
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The heart’s pumping action is controlled by an electrical system that sends out impulses, or signals. An electrical signal starts in the right atrium in the sinus node (1), also called the sino-atrial node. The sinus node tells the atria when and how fast to pump. It is the “pacemaker” of the heart.
The signal is then sent to the atrioventricular node (4), or AV node, in the middle of the heart. The AV node holds the signal until the ventricles are filled with blood. It then sends the signal to the ventricles (5) and tells them when to pump the blood out of the body.
As long as the electrical impulse is transmitted normally, the heart pumps and beats at a regular pace. An arrhythmia causes the heart to pump and beat at an irregular pace – the heart may beat too fast or too slowly, or may skip beats. A person with an arrhythmia may feel palpitations: a rapid heart rate, skipped beats, thumping or pounding of the chest. An arrhythmia also may cause feelings of anxiousness, nervousness, dizziness, faintness or shortness of breath.
Types of Arrhythmia
Arrhythmias commonly are divided into two categories: tachycardia (too fast a heartbeat) and bradycardia (too slow a heartbeat).
Tachycardia
Tachycardia is heart rate more than 100 beats per minute. Tachycardia often results when the sinus node loses control of the heart rhythm. Another common cause of tachycardia, called reentry, occurs when the heart impulses get caught in a merry-go-round-like sequence. Some originate in the atria (supraventricular tachycardia) while other, more serious, conditions involve only the ventricles (ventricular tachycardia). Most arrhythmias that fall into this group can produce symptoms of palpitations, rapid heart action, dizziness, lightheadedness, fainting or near fainting. In some cases, tachycardia can cause sudden cardiac death.
Forms of tachycardia:
- Sinus Tachycardia
- Supraventriuclar Tachycardia
- Atrioventriuclar Nodal Reentrant Tachycardia
- Bypass Medicated Tachycardia
- Atrial Tachycardia
- Atrial Flutter and Fibrillation
- Ventricular Tachycardia
- Ventricular Fibrillation
Bradycardia
Bradycardia is too slow a heartbeat, less than 60 beats per minute. This can be caused by the sino-atrial node not working properly or by the blockage of the electrical pathways of the heart. Less common than tachycardia, these arrhythmias can cause fatigue, dizziness, lightheadedness, fainting or near-fainting spells. In serious cases, bradycardia can even cause cardiac arrest.
Forms of bradycardia:
- Sinus Bradycardia
- AV Nodal Block, including complete heart block
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