Arrhythmia: Irregular Heartbeat
When the electrical system of the heart is not functioning correctly and the heartbeat it generates is too fast, too slow, or irregular, the condition is described as a heart rhythm disorder, or arrhythmia. Arrhythmias can last for seconds, minutes, hours, or days.
The heart is a strong muscle that pumps blood to the rest of the body, to keep tissues and organs alive and functional. This organ is divided into two upper chambers (atria) and two lower chambers (ventricles).
The heart's regular electrical activity starts from a small group of cells in the right upper chamber (right atrium), known as the sinus node or the heart's natural pacemaker. The electrical signals travel from the upper chambers to the lower chambers, causing the heart muscle to contract. The electrical system of the heart controls the timing of the contractions.
The heart creates a pulse or a heartbeat every time it contracts. A healthy heart has a strong and regular heartbeat, which is an indication that the right amount of blood is being pumped to the rest of the body. This is called a normal sinus rhythm.
The number of heartbeats that can be counted in one minute represent the heart rate, which, in a healthy heart, usually ranges from 60 to 100 heartbeats per minute. When the electrical system of the heart does not function properly, the natural pacemaker may send false signals to other heart cells, or may deliver an incomplete message. The heart responds to these incorrect or incomplete messages by beating faster or slower than it usually would, or by pounding in an unpredictable pattern.
If you think you have an arrhythmia or you have a family history of the condition, schedule an evaluation with Dr. Alireza Nazeri in Houston, Texas. To reach us, call (713) 790-9125.
Types of Arrhythmia
- Asystole describes what happens when the part of the heart that generates or conducts electrical signals stops working. This appears as a “flat line” or a pause on the electrocardiogram (EKG) that records the heart's electrical activity.
- Bradycardia is an abnormally slow heart rate. In general, a heart rate that is slower than 60 beats per minute is considered bradycardia.
- Tachycardia is an abnormally fast heart rate, typically more than 100 beats per minute.
- AV node disease: The atrioventricular, or AV, node is a small area between the atria and the ventricles that enables electrical signals to travel properly from the upper to the lower chambers. Abnormalities in the AV node can cause the heart to beat too slowly.
- Sinus node disease: The sinus node, also called the heart's natural pacemaker, is located in the right upper chamber of the heart. Its role is to start and control the electrical activity of the heart. When the heart's pacemaker is not functioning correctly, the heart can beat very slowly or even stop beating.
- Atrial fibrillation, also known as AFib or AF, is an irregular heartbeat that causes the heart to quiver and to become inefficient at pumping blood to the rest of the body. During AFib, the heart usually beats very fast. Learn more about AFib.
- Atrial flutter: This term describes out-of-sync heart contractions, which happen when the electrical signals travel fast around a large and unusual circuit in the upper chambers of the heart, causing an abnormally fast heartbeat (tachycardia). The most common form of atrial flutter shows up as a “sawtooth” pattern on the electrocardiogram (EKG).
- Supraventricular tachycardia (SVT) is an abnormally fast heartbeat (usually faster than 100 beats per minute) that starts in the upper chambers of the heart. There are different types of SVT:
- Atrial tachycardia is a heart rate that ranges from 100 to 220 beats per minute, which occurs when electrical signals are sent from an area of the upper chambers of the heart (atria) other than the sinus node or the pacemaker cells.
- AVNRT, or atrioventricular nodal reentry tachycardia, is the most common form of SVT, which occurs when the presence of an abnormal electrical circuit in the AV node causes the heart to beat too early. Episodes start suddenly and are typically brief. This type of tachycardia is more common in young women than in any other demographic group.
- WPW (Wolff-Parkinson-White syndrome) is a fast heartbeat that occurs when the heart uses a pathway other than the AV node to send electrical signals from the upper to the lower chambers.
- PVC, also known as premature ventricular contractions, is a fairly common condition in which the lower chambers of the heart produce additional, abnormal heartbeats; these can be felt as a fluttering in the chest or a sensation of skipped heartbeats.
- PAC, or premature atrial contractions, occurs when extra heartbeats start in an area of the atria outside of the sinus node, creating an abnormally fast heartbeat.
- Ventricular tachycardia occurs when faulty electrical signals transmitted from the lower chambers cause the heart to beat abnormally fast.
- Ventricular fibrillation results from changes in the electrical activity in the ventricles, which cause fast, irregular heartbeats. When experiencing this arrhythmia, the heart will often quiver instead of pumping blood efficiently through the body.
- Cardiac arrest occurs when the heart stops working and the blood supply to vital organs such as the brain is compromised. This is a life-threatening condition that can lead to sudden cardiac death when not managed properly.
Symptoms of Arrhythmia
Some individuals may have silent, undetected arrhythmias that do not cause any symptoms. However, people who have arrhythmias may experience any of the following symptoms:
- Palpitations, which are felt as a fast, irregular heartbeat, fluttering, or a sensation that the heart is pounding or pumping too hard
- Skipped beats
- Fainting (syncope)
- Near fainting
- Dizziness and lightheadedness
- Shortness of breath
- Chest pain and discomfort
- Fatigue and lack of energy
- Sleeping problems
Risk Factors for Arrhythmia
Certain health conditions can increase the risk of developing arrhythmias. These include:
- Coronary artery disease (CAD)
- Uncontrolled high blood pressure (hypertension)
- Kidney disease
- Heart failure (heart muscle weakness)
- Electrolyte imbalances (e.g., potassium or magnesium)
- Damage to the heart muscle from a heart attack
- Hereditary disorders
- Sleep apnea (a disorder in which breathing stops for several seconds during sleep)
- Obesity: The risk of developing arrhythmias is higher in overweight and obese people compared with normal-weight individuals. Maintaining a healthy weight can help prevent arrhythmias.
- Depression: Individuals who feel depressed frequently are more likely to have arrhythmias such as atrial fibrillation.
Consuming certain substances and engaging in certain activities can also increase the likelihood of experiencing arrhythmias:
- Alcohol use: Drinking too much alcohol and binge drinking can cause arrhythmias.
- Caffeine intake: Caffeine is a stimulant, which, when consumed in excess, can trigger or worsen arrhythmias.
- Nicotine use: Nicotine is a stimulant that can increase the risk for arrhythmias.
- Medications: Some cold medicines contain stimulants, such as pseudoephedrine, that can cause arrhythmias.
- Weight-loss and herbal supplements: Certain supplements contain ingredients that can stimulate the heart and increase the risk for arrhythmias. Some reports have linked certain herbal supplements to life-threatening arrhythmias and cardiac arrest.
- Exercise: Physical activity that gets your heart pumping can help prevent arrhythmias by strengthening your heart. Nevertheless, heavy weightlifting, competitive and contact sports, and other activities that put too much stress on the heart can cause arrhythmias.
- Allergy medications: Some allergy medications contain decongestants that can cause arrhythmias because they raise the blood pressure by constricting blood vessels.
Why Does a Family History of Arrhythmia Matter?
Certain arrhythmias run in the family. We now know that genetics play a role in causing arrhythmias. In fact, genetic links have been found in nearly half of all sudden deaths related to heart disease that occurred in young people.
Hereditary heart disorders that increase the risk for life-threatening arrhythmias include:
- Brugada Syndrome: This genetic disorder can cause the lower chambers of the heart (ventricles) to move in an erratic pattern (quiver), which is known as ventricular fibrillation. It can also cause the heart to stop beating suddenly (cardiac arrest).
- Hypertrophic cardiomyopathy: This condition arises when faulty calcium pumps in the heart interfere with the transmission of electrical signals, resulting in heartbeat irregularities. These become apparent especially during exercise.
- Long QT syndrome is a potentially deadly condition that can cause life-threatening arrhythmias.
- Arrhythmogenic right ventricular cardiomyopathy (ARVC) is a genetic condition that increases the risk for abnormally fast heartbeats that begin in the ventricles (ventricular tachyarrhythmias) and for sudden cardiac death.
Role of the Cardiac Electrophysiologist
The cardiac electrophysiologist (EP) is a cardiologist who receives additional training in diagnosing and treating heart rhythm disorders (arrhythmias) and specializes in managing patients with these conditions.
Diagnosis of Arrhythmias
If you experience symptoms that suggest arrhythmias, you may need to consult a cardiac electrophysiologist (EP). Your doctor will ask a series of questions related to your symptoms, perform a physical examination, and recommend specific tests to find out if you have an arrhythmia and, if so, what causes it.
- Medical history: During your visit, your doctor will ask questions about any symptoms you have experienced, your medical history, your family history, and other relevant information that can help the physician determine your risk for arrhythmia.
- Physical examination: The physician will also check your pulse and blood pressure, listen to your heart to identify any irregular heart rhythms or murmurs, and perform a thorough examination.
- The electrocardiogram (also known as ECG or EKG) is the most common test doctors use to evaluate the electrical activity of your heart and look for abnormal heart rhythms.
- Holter monitors are wearable devices that can identify and record abnormal heart rhythms. Your doctor might ask you to wear such a monitor for one or several days while you perform your usual daily activities.
- The implantable loop recorder is a recording device that can be placed underneath your skin to monitor your heart for arrhythmias over long periods of time.
- The echocardiogram or heart ultrasound is a noninvasive test used to collect images of your heart, to look closely at its size, function, structure, and motion.
- Testing for coronary artery disease: Your doctor may order tests to check if you have narrowing or blockages in the arteries that supply oxygen-rich blood to your heart muscle (coronary arteries). These tests can be noninvasive (eg, cardiac stress test, CT scan), or invasive (e.g., coronary angiography or heart catheterization).
Blood tests can be ordered to check the function of your thyroid, kidneys, and liver, cholesterol levels, blood sugar levels, electrolytes (potassium and magnesium), and other substances in your blood.
Treatment of Arrhythmias
Your doctor will recommend a treatment plan that is tailored to your specific arrhythmia and underlying heart condition(s). A treatment plan can include:
- Modification of the risk factors: The physician will work with you to identify and address the risk factors that can make you more susceptible to developing arrhythmias. This can include making lifestyle changes such as reducing alcohol or caffeine consumption, treating thyroid dysfunction, or managing sleep apnea.
- Medications: There are certain medications that were specifically designed to treat arrhythmias. These are called antiarrhythmic medications. Amiodarone, propafenone, and sotalol are some of the most commonly used antiarrhythmic drugs.
- Pacemaker: This device that imitates the function of the heart’s natural pacemaker generates electrical impulses and causes the heart to contract.
- Implantable cardioverter defibrillator (ICD): This device continuously monitors your heart rhythm and, when you experience life-threatening arrhythmias, it can restore your normal rhythm by delivering an electric shock.
- Cardioversion: A medical procedure performed to restore your heart's normal sinus rhythm. Physicians can use medications or electric current to correct your arrhythmia.
- Catheter ablation: During this procedure, your doctor inserts a flexible tube (catheter) into a major blood vessel in your leg and guides it to certain areas of your heart, where the catheter is used to destroy abnormal tissues that cause arrhythmias.