Table of Contents
What is Arrhythmia and Definition
Arrhythmia is irregularity or abnormality of the heart’s contractions. Arrhythmias can result from numerous causes including electrical disturbances of the heart’s pacing mechanisms, physical damage to the HEART such as might occur with HEART ATTACK, interruptions of the heart’s BLOOD supply that cause myocardial HYPOXIA (oxygen depletion), severe electrolyte imbalances, and medication side effects. COCAINE use can initiate sudden and fatal arrhythmias. Because all myocardial cells have the ability to initiate electrical impulses, it is sometimes difficult for cardiologists to determine what causes an arrhythmia.
Types of Arrhythmia
The most common kinds of arrhythmias are
- bradycardia, in which contractions are slower than normal (typically fewer than 60 beats per minute at rest in a person whose level of routine physical activity is low)
- tachycardia, in which contractions are faster than normal (typically greater than 100 beats per minute at rest in a person whose level of routine physical activity is low)
- fibrillation, in which contractions are rapid, erratic, and nonproductive
- premature or extra beats, in which contractions occur in addition to the heart’s regular contractions
The seriousness of an arrhythmia depends largely on whether it is atrial or ventricular. Typically ventricular arrhythmias are more significant and potentially hazardous than atrial arrhythmias. The most common arrhythmia that requires treatment is ATRIAL FIBRILLATION, which health experts estimate affects about one in five American adults over age 60 and which accounts for about 15 percent of strokes. The most deadly arrhythmia is VENTRICULAR FIBRILLATION, which results in seriously slowing or even halting the flow of blood to the body because the ventricles cannot pump in a coordinated manner. Some arrhythmias are transient (come and go), and others cause no symptoms or effect on cardiovascular function.
Symptoms of Arrhythmia and Diagnostic Path
Arrhythmias may cause a range of symptoms or no symptoms at all. The most common symptoms are
- PALPITATIONS, which feel like the heart is thumping or “skipping” a beat
- weakness, lightheadedness, or fainting
- shortness of breath with exertion (DYSPNEA)
- CHEST PAIN
It is not possible to know only from the symptoms what kind of arrhythmia is present. Only an ELECTROCARDIOGRAM (ECG), a test that records the heart’s electrical activity, can present the information a cardiologist needs to determine the diagnosis. The cardiologist may desire further diagnostic procedures to identify any underlying causes, as the findings may influence treatment options and decisions. Arrhythmias resulting from CORONARY ARTERY DISEASE (CAD) or HEART FAILURE, for example, require different treatment than those resulting from idiopathic electrical disturbances (problems with the heart’s pacing mechanisms that have no apparent cause). Occasionally the doctor detects an arrhythmia during examination for other health concerns, which requires subsequent evaluation to determine whether, as it is not causing symptoms, it is a condition that warrants treatment.
Arrhythmia Treatment Options and Outlook
CAFFEINE and ALCOHOL consumption can cause palpitations and other minor, benign arrhythmias, as can intense stress. Making lifestyle changes to reduce or eliminate these factors typically ends the arrhythmias related to them. Arrhythmias that are not clinically significant (those that cause no symptoms or disruptions of cardiovascular function) do not require treatment, though cardiologists generally want to monitor them to make sure they remain benign. Antiarrhythmia medications successfully treat the majority of symptomatic arrhythmias. These medications work by blocking certain aspects of the biochemical functions responsible for myocardial contractions. The cardiologist may prescribe two or more antiarrhythmia medications in combination to treat some kinds of arrhythmias. People who have heart failure, CAD, valvular disease, and other heart disorders may take antiarrhythmia medications along with other medications to treat these conditions.
Cardiologists select antiarrhythmia medications based on the characteristics of the arrhythmia, which may be simple or complex, as well as the presence of other cardiovascular conditions, any other medications the person may be taking, and factors such as age and lifestyle. After starting antiarrhythmia therapy, it is important to continue until the cardiologist makes changes in the therapeutic approach. Suddenly stopping an antiarrhythmia medication can have significant consequences including serious arrhythmias.
Antiarrhythmia medications can have serious side effects such as worsening the existing arrhythmia or causing new arrhythmias. Some medications work by causing heart block, for example, to interrupt the conduction of aberrant electrical impulses. Finding the right medication or combination of medications sometimes takes a period of trial regimens and dosages. As the condition responsible for the arrhythmia changes over time, sometimes it becomes necessary to change the medication regimen as well.
Other interventions may become necessary if medications are ineffective or generate intolerable side effects. Such interventions may include
- CARDIOVERSION, in which the cardiologist delivers (under sedation) a mild electrical shock through the chest wall to reorganize and restore to normal the heart’s electrical activity
- RADIOFREQUENCY ABLATION, a cardiac catheterization procedure in which the cardiologist uses radiofrequency impulses to kill a small and carefully targeted segment of myocardial cells to prevent them from initiating or conveying electrical impulses
- implantable PACEMAKER, a small battery-operated device that emits an electrical impulse to trigger the heart’s contractions
- IMPLANTABLE CARDIOVERTER DEFIBRILLATOR (ICD), which functions both to deliver pacing impulses and shocking impulses to convert an arrhythmia that extends beyond certain parameters
Most people are able to successfully control or eliminate arrhythmias with appropriate treatment, resulting in no changes to lifestyle or quality of life.
Arrhythmia – Risk Factors and Preventive Measures
Most arrhythmias arise as a consequence of other CARDIOVASCULAR DISEASE (CVD) or are idiopathic (without identifiable cause). Some arrhythmia disorders are congenital or genetic, such as LONG QT SYNDROME (LQTS). People who have one kind of arrhythmia are prone to developing others. Prompt medical evaluation of symptoms that could signal cardiovascular disease or arrhythmias is important, as early detection and treatment may head off consequences such as CARDIAC ARREST or SUDDEN CARDIAC DEATH.
See also AUTOMATED EXTERNAL DEFIBRILLATOR (AED); BUNDLE BRANCH BLOCK; CARDIOPULMONARY RESUSCITATION (CPR); GENERIC DRUG; PAROXYSMAL ATRIAL TACHYCARDIA (PAT); PREMATURE VENTRICULAR CONTRACTION; STRESS AND STRESS MANAGEMENT; STROKE; TORSADE DE POINTES; WOLFF-PARKINSONWHITE SYNDROME.