An irregularity in the heart’s natural rhythm is called an arrhythmia. Almost everyone’s heart skips a beat or flutters at one time or another, and these mild, one-time palpitations are harmless. However, approximately 4 million Americans have recurrent clinical arrhythmias that require the care of a doctor. Arrhythmias can be life threatening, and they lead to nearly 400,000 deaths in the United States each year.
Categories of Arrhythmia
Arrhythmias can be divided into two categories: ventricular and supraventricular. Ventricular arrhythmias originate in the heart’s lower chambers, or ventricles. Supraventricular arrhythmias originate in the heart’s upper chambers, or atria. Heart block is a type of arrhythmia that prevents electrical signals from traveling from the atria to the ventricles.
Arrhythmias are further defined by the speed of the heartbeats. A very slow heart rate, called bradycardia, is a heart rate less than 60 beats per minute. A very fast heart rate, called tachycardia, is a heart rate faster than 100 beats per minute. Fibrillation, the most serious form of arrhythmia, consists of fast, uncoordinated beats caused by contractions of individual heart muscle fibers.
Causes of Arrhythmia
Many different factors can cause an irregular heartbeat. An arrhythmia can be:
• inborn or congenital
• caused by a medical condition like heart disease or high blood pressure
• environmentally linked to stress, caffeine, smoking, alcohol, and some over-the-counter cough and cold medicines
Arrhythmia symptoms depend on the overall health of the heart, the type, severity, and frequency of the arrhythmia, and the length of the episode. Some arrhythmias do not produce any warning signs. Surprisingly, heart palpitations do not always indicate an arrhythmia.
Symptoms of bradycardia (a slow heart rate) include tiredness, shortness of breath, dizziness, or fainting. Symptoms of tachycardia (a fast heart rate) include a strong pulse in the neck or a fluttering, racing heartbeat in the chest along with chest discomfort, weakness, shortness of breath, fainting, sweating, or dizziness.
Many different diagnostic tools and techniques are used to diagnose arrhythmias, including:
• Electrocardiogram (ECG)
• Holter Monitoring
• Event Monitoring
• Electrophysiology Studies (EPS)
• Exercise Stress Test
• Tilt-table Testing
• Transthoracic Echocardiogram (TTE)
• Transesophageal Echocardiogram (TEE)
Due to the complexity of some arrhythmias and the potential health problems of some patients who have them, a comprehensive diagnosis involving many different diagnostic tests is critical in determining the best treatment options for each patient.
The decision for medical treatment, and the method selected, can be made only after a comprehensive diagnosis. Medications, interventional procedures, device implantation, and cardiac surgery are all possible treatment options depending of the type and severity of the arrhythmia. Medical treatment is required if the arrhythmia is causing significant symptoms or if it is putting the patient at risk for more serious complications. Some non-serious types of arrhythmia do not require medical treatment, in which case the patient is seen for scheduled medical check-ups.
Antiarrhythmic medicines, including digitalis, beta blockers, calcium channel blockers, and anticoagulants are used to treat arrhythmias. Other treatments include percutaneous (or catheter-based) interventions, implantable devices, and surgery. The type and severity of the arrhythmia determines the treatment needed.
Percutaneous catheter intervention procedures that might be used to diagnose and treat an arrhythmia include medicine-induced and electrical cardioversion, catheter radiofrequency ablation, cryoablation, and pulmonary vein ablation.
Battery-powered implantable devices that are used to treat arrhythmias include electronic pacemakers and internal cardioverter defibrillators (ICDs).
Surgical options remove or destroy heart tissue that is causing the arrhythmia. Surgery may also be required to treat underlying disease, such as a coronary artery blockage. Surgical options to treat arrhythmias include surgical ablation, cryoablation, maze surgery, and ventricular resection.
In some cases, no treatment is needed. Most people with an arrhythmia lead normal, active lifestyles. Often, certain lifestyle changes, such as avoiding caffeine or alcohol, are enough to stop the arrhythmia.
The medical team for heart arrhythmia patients is usually led by a doctor called an electrophysiologist. These specialized cardiologists perform electrophysiology studies (EPS) and other testing for potentially serious arrhythmias.
Texas Heart Institute www.texasheartinstitute.com/HIC/Topics/Cond/Arrhythmia.cfm
Hoag Heart Institute www.hoaghospital.org/heartinstitute/Rhythms.aspx
Mayo Clinic www.mayoclinic.org/arrhythmia/index.html
American Heart Association http://americanheart.org/presenter.jhtml?identifier=8
Medline Plus www.nlm.nih.gov/medlineplus/arrhythmia.html