Heart rhythm problems and what it means
Heart rhythm problems, or arrhythmias, occur when the electrical impulses that coordinate your heartbeats don't work properly, causing your heart to beat too fast, too slow or irregularly.
Arrhythmias may not cause any signs or symptoms. However, having symptoms does not necessarily mean you have a serious problem. In fact, your doctor might find you have an arrhythmia before you do, during a routine examination.
Noticeable arrhythmia symptoms may include:
• Palpitations or fluttering in the chest
• Chest pain
• Shortness of breath
• Lightheadedness or dizziness
• Fainting (syncope) or near fainting
Many things can lead to, or cause an arrhythmia, including:
• An ongoing heart attack or heart muscle scarring from a prior attack
• Blocked cardiac vessels (coronary artery disease or CAD)
• Changes to your heart's structure, such as from cardiomyopathy or valve problem
• High blood pressure
• Sleep apnoea
• Electrolyte imbalance
• Over- or underactive thyroid gland
• Smoking, excess caffeine or alcohol use, drug abuse and stress
• Certain medications and supplements, including over-the-counter cold and allergy drugs and nutritional supplements
Types of arrhythmias
Arrhythmias are classified according to:
• The heart chambers they originate from: upper chambers (atria) or lower chambers (ventricles).
• By the speed of heart rate they cause: tachycardia refers to a fast resting rate (greater than 100 beats a minute), and bradycardia refers to a slow heartbeat (less than 60 beats a minute).
It is important to mention that not all tachycardias or bradycardias mean you have heart disease. For example, during exercise, it is normal to develop a fast heartbeat as the heart speeds up to provide your tissues with more oxygen-rich blood. During sleep, or times of deep relaxation, it is not unusual for the heartbeat to be slower. Also, if you are physically fit, you may have an efficient heart capable of pumping an adequate supply of blood with fewer than 60 beats per minute, at rest. In addition, certain medications used to treat high blood pressure or CAD may lower your heart rate (usually an acceptable side effect).
Tachycardias in the atria
• Premature atrial beats: Although it often feels like a “skipped” beat, a premature beat is actually an extra beat. PAB seldom means you have a serious cardiac problem. It is commonly caused by stress, exercise, thyroid disease or stimulants such as caffeine or nicotine. In some cases, they could precede development of atrial fibrillation.
• Atrial fibrillation: A rapid heart rate caused by chaotic electrical impulses in the atria. A fib may be temporary, but some episodes won't end unless treated. It may lead to serious complications such as stroke.
• Atrial flutter: It is similar to atrial fibrillation though the heartbeats in atrial flutter are more organised and rhythmic. Atrial flutter may also lead to stroke.
• Supraventricular tachycardia: A broad term that includes many forms of fast rhythms originating in the AV node (the connection between atria and ventricles), or in an extra and abnormal electrical pathway between atria and ventricles (Wolff-Parkinson-White syndrome).
Tachycardias in the ventricles
• Premature ventricular beats: Like premature atrial beats, they could cause palpitations. Unlike PABs, PVBs tend to occur more in diseased hearts.
• Ventricular tachycardia: A rapid, regular heart rate that originates with abnormal electrical signals in the ventricles. The rapid heart rate doesn't allow the ventricles to fill and contract efficiently to pump enough blood to the body. VT can often be a medical emergency. Without prompt medical treatment it may worsen into ventricular fibrillation.
• Ventricular fibrillation: This occurs when rapid, chaotic electrical impulses cause the ventricles to quiver ineffectively instead of pumping necessary blood to the body. This serious problem is fatal if the heart is not reset to a normal rhythm within minutes, by an electrical shock. Most people who experience VF have an underlying heart disease or have experienced serious trauma, such as being struck by lightning.
• Sick sinus syndrome: If your sinus node, which is responsible for setting the pace of your heart, isn't sending impulses properly, your heart rate may be too slow.
• Conduction block: A block of your heart's electrical pathways can occur in or near the AV node (electrical wire connecting atria and ventricles). If an advanced form of block develops, it becomes a source of severe bradycardia with dizziness or fainting. It is important to note that in some patients both forms of arrhythmias, slow and fast, could be recorded.
In next week's column, diagnosis and treatment of arrhythmias will be discussed.
• Joe Yammine is a cardiologist at Bermuda Hospitals Board. He trained at the State University of New York, Brown University and Brigham and Women's Hospital. He holds five American Board certifications. He was in academic practice between 2007 and 2014, when he joined BHB. During his career in the US, he was awarded multiple teaching and patients' care recognition awards. The information herein is not intended as medical advice nor as a substitute for professional medical opinion. Always seek the advice of your physician. You should never delay seeking medical advice, disregard medical advice or discontinue treatment because of any information in this article.
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