What Are the Causes of Cardiac Dysrhythmia?

A cardiac dysrhythmia, or arrhythmia, is a change in the normal rhythm of the heart. Some occur in perfectly healthy hearts and are benign. Some are relatively common, such as atrial fibrillation, which, according to the American Heart Association, is seen in more than 2 million people in America. Some dysrhythmias, however, are much more serious and can be precursors to cardiac arrest or stroke. There are several reasons a dysrhythmia may occur, all dealing with the electrical system of the heart.

Types

• There are four main classifications of dysrhythmias. The average heart beats 60 to 100 times per minute. Bradycardia is diagnosed in people with a heart that beats slower than normal. Tachycardia is a heart rate that is faster than normal. Another type of dysrhythmia is fibrillation, which is when the heart quivers instead of contracts. Premature contractions are heartbeats that occur before they should, leaving a pause before the next regular heartbeat.

Cardiac Electrical System

• The heart is regulated by a complex electrical system. Special myocardial cells in the muscular layer of the heart, or myocardium, pass along an electrical impulse that stimulates the contraction of the heart. A defect anywhere along the route can result in a dysrhythmia.

Abnormal Natural Pacemaker

• The sinoatrial, or SA, node of the heart is responsible for the heart rate. This is where the electrical impulse, which causes contraction, originates. If something goes awry with the SA node, that will cause the heart to either speed up or slow down.

Secondary Pacemakers

• If the SA node is damaged or not working properly, other parts of the heart may try to act as the pacemaker, setting the rate of the heartbeat. This causes a dysrhythmia since the normal impulses are not occurring and the rate of the heart becomes abnormal, usually with cardiac function being compromised.

Interrupted Conduction

• The electrical impulse typically travels from the SA node to the atrioventricular, or AV, node and then to the bundle of His and right and left bundle branches to stimulate all cells of the myocardium, or muscular layer of the heart. If there is a block in this pathway due to some type of cardiac damage, a dysrhythmia will occur.

Treatment

• There are many ways to treat dysrhythmias. Medication may control symptoms and prevent blood clots that may be caused by some dysrhythmias. Pacemaker implantation is another treatment option for some, where a device is placed in the chest to regulate the heartbeat. Defibrillation, or shocking, may be necessary in serious cases to bring the heart back to a normal rhythm.

Be Aware of Medications and Stimulants

• Many different medications may alter the rate of the heartbeat. Epinephrine and calcium channel blockers, a type of blood pressure medication, will speed the heart rate. Tobacco and caffeine are two stimulants that are also capable of increasing the rate of the heart. Other medications, such as beta-blockers, slow the heart rate. Be aware of any cardiac side effects of medications. Seek medical help if you are suffering from chest pain, feel dizzy or are very fatigued.