Arrhythmias
An arrhythmia is an abnormal heart rhythm. Some arrhythmias can cause problems with contractions of your heart chambers by:
- Not allowing the lower chambers (ventricles) to fill with enough blood, because an abnormal electrical signal is causing your heart to pump too fast or too slow.
- Not allowing enough blood to be pumped out to your body, because an abnormal electrical signal is causing your heart to pump too slowly or too irregularly.
- Not allowing the top chambers (atria) to work properly.
An arrhythmia occurs when there is a problem with the electrical system that is supposed to regulate a steady heartbeat. With an impaired electrical system, your heart may beat too fast, too slow or irregularly. An arrhythmia can occur in the sinus node, the atria or the atrioventricular node. These are supraventricular arrhythmias.
A ventricular arrhythmia is caused by an abnormal electrical focus within your ventricles. This results in abnormal conduction of electrical signals within your ventricles. Arrhythmias can also be classified as slow (bradyarrhythmia) or fast (tachyarrhythmia).
In any of these situations, your body's vital organs may not get enough blood to meet their needs. Some arrhythmias have no complications. However, arrhythmias that are more serious can result in heart failure, stroke or even cardiac arrest.
Risk Factors
Many risk factors can affect the electrical system of your heart and, therefore, cause an arrhythmia. Substances including caffeine, alcohol, tobacco, illegal drugs, diet drugs, some herbs and even prescription medicines can trigger an arrhythmia. Health conditions including coronary heart disease, high blood pressure and diabetes contribute to developing arrhythmias. Arrhythmias become more common with age.
Symptoms
- Palpitations (a sensation of fluttering or irregularity of the heartbeat)
- Weakness
- Fatigue
- Low blood pressure
- Dizziness
- Fainting
- Heart failure
- Collapse and cardiac arrest
- Difficulty feeding (in babies)
Diagnosis
There are several tests that may be used to diagnose arrhythmias.
An electrocardiogram (ECG) can show the presence of arrhythmias, damage to your heart caused by ischemia (lack of oxygen to the heart muscle) or heart attack, a problem with one or more of the heart valves, or other types of heart conditions.
There are several variations of the ECG test:
- Resting ECG: Electrodes are attached to chest, arms and legs that record the heart's electrical activity for a minute or so while the patient is lying down.
- Stress Test: Electrodes are attached as above, but rather than lying down the patient walks on a treadmill or pedals a stationary bike.
- Signal-averaged ECG: Electrodes are attached as with a resting ECG, but for 15 to 20 minutes.
- Electrophysiologic studies (EPS): A nonsurgical but invasive test in which a small, thin tube (catheter) is inserted into a large blood vessel in the leg or arm and advanced to the heart. .
- Holter monitor: A continuous ECG recording done over a period of 24 or more hours. Electrodes are attached to the chest and connected to a small portable ECG recorder by lead wires.
- Event monitor: Similar to a Holter monitor, except the patient starts the ECG recording only when they feel symptoms. Event monitors are typically worn longer than Holter monitors.
- Mobile cardiac monitoring: Similar to both a Holter and event monitor, the ECG monitors constantly to allow for detection of arrhythmias. The patient can also start recordings when they have symptoms. These monitors can be worn up to 30 days.
- Implantable loop recorder: A miniature heart recording device implanted underneath the skin overlying the heart. It can record heart rhythm for up to two years and is useful in diagnosing intermittent or rarely occurring arrhythmias.
Treatments
Not all arrhythmias require treatment. For those that do, options include:
- Lifestyle changes
- Medicine
- Cardioversion
- Ablation
- Pacemaker
- Implantable cardioverter defibrillator (ICD)
- Surgery