Palpitations

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Medical Author:

Benjamin Wedro, MD, FACEP, FAAEM

Benjamin Wedro, MD, FACEP, FAAEM

Dr. Ben Wedro practices emergency medicine at Gundersen Clinic, a regional trauma center in La Crosse, Wisconsin. His background includes undergraduate and medical studies at the University of Alberta, a Family Practice internship at Queen's University in Kingston, Ontario and residency training in Emergency Medicine at the University of Oklahoma Health Sciences Center.

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Medical Editor:

Melissa Conrad Stöppler, MD, Chief Medical Editor

Melissa Conrad Stöppler, MD, Chief Medical Editor

Melissa Conrad Stöppler, MD, is a U.S. board-certified Anatomic Pathologist with subspecialty training in the fields of Experimental and Molecular Pathology. Dr. Stöppler's educational background includes a BA with Highest Distinction from the University of Virginia and an MD from the University of North Carolina. She completed residency training in Anatomic Pathology at Georgetown University followed by subspecialty fellowship training in molecular diagnostics and experimental pathology.

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• Palpitations Overview
• Types of Palpitations
• Palpitation Causes
• Palpitation Symptoms
• Palpitations Diagnosis
• Palpitations Treatment
• Self-Care at Home
• Palpitations Medical Treatment
• Next Steps
• Palpitations Prognosis
• Synonyms and Keywords
• Authors and Editors
• Viewer Comments: Palpitations - Treatment
• Viewer Comments: Palpitations - Effective Treatments

Palpitations Overview

The heart is a two stage electrical pump. The upper chambers of the heart, the atria, (single=atrium) collect blood from the body and pump it into the lower chambers, or ventricles. There is a little delay for the ventricles to fill, and then they pump the blood out of the heart and back to the body. For this to happen in a coordinated fashion, the heart has its own electrical system

Specialized electrical cells imbedded into part of the muscles in the atrium generate the electricity and act as a pacemaker for the heart. About 60-80 times a minute this pacemaker (the sinoatrial or SA node) fires and sends electrical signals to all of the atrial muscle cells allowing them to fire at once, generating the first half of a heart beat. Electricity also travels to the ventricles but is held up for a split second in the junction between the atrium and ventricle at the atrio-ventricular (AV) node to allow the ventricles to fill with blood. The signal then travels through electrical bundles to allow all the muscle cells of the ventricles to fire at once, causing the second half of the heart beat. This pumps blood out to the body. After the heart pumps, there is another split second when the electrical system resets itself to get ready for the next electrical impulse cycle. This allows blood to return and fill the heart, getting ready for the next heartbeat.

Palpitations is a term that describes the feeling that occurs when a person can feel an abnormality in the normal beating of the heart. These palpitations can be an isolated extra beat, or they can run together and last for prolonged periods of time. Each part of the heart has the potential to be irritable and cause an extra beat to occur. As well, short circuits in the electrical conduction system of the heart can cause "runs" of abnormal firing.

Every muscle cell in the heart has the potential to generate an electrical signal that can spread outside the normal electrical pathways and bundles to try to generate a heart beat. If the SA node fails, then other cells in the atrium try to take over. If they fail, then the AV node can take over but at a lower rate of about 40 beats per minute. And as the final backup, the ventricle itself can generate electricity but at a much slower rate of about 20 beats per minute.

Types of Palpitations

Extra heart beats are normal and most people are unaware that they have occurred. Every muscle cell in the heart has the potential to generate an electrical signal that can spread outside the normal electrical pathways and bundles to try to generate a heart beat. Many extra beats are normal variants and can be nothing more than an occasional irritant, but others can be dangerous - either acutely or chronically. Extra beats that originate in the atrium tend not to be as serious as those that come from the ventricle.

Abnormal heartbeats are classified by the location where they originate, if they happen occasionally or if they are clustered in runs, and if they resolve by themselves (self-limiting).

PACs and PVCs

Premature atrial contractions (PAC) are just as the name describes. The pacemaker or SA node in the atrium decides to send a signal out before the heart is quite ready, and while it conducts normally and the heart beats, it is felt as a slight flop or thump in the chest.

A similar situation can occur with the ventricle if it becomes a little irritable and generates an extra beat, known as premature ventricular contractions (PVC). This beat fires the ventricle when there is little blood in the heart to pump, and again a flop or thump can be felt by the person.

PACs and PVCs in isolation are a normal variant. They can be asymptomatic, and an individual may not be aware of them.

Supraventricular Tachycardia (SVT)

If the electrical system in the atrium becomes irritable, it can cause the upper chamber to beat very fast, sometimes 150 beats or more per minute. The AV node senses each beat and sends it to the ventricle which itself responds with a beat. Because the electricity is generated above the ventricle and then passed down, the whole group of disorders is classified as supraventricular tachycardias (supra= above, tachy=fast).

Some supraventricular tachycardias are a normal response to specific situations. In times of stress, when the body wants to send more blood and oxygen to the body, like with exercise, trauma or illness, the heart rate rises in response to adrenalin that is secreted by the body to meet its physiologic demand. Caffeine, pseudoephedrine, and other stimulants can also cause this type of rapid heart beat. Because all the electrical impulses begin in the SA node, this is called sinus tachycardia.

Some supraventricular tachycardias occur because of short circuits in the electrical conducting pathways in the atrium causing the heart to beat fast without apparent cause. Paroxysmal supraventricular tachycardias (PSVT) occur without warning and may last for seconds to hours. Specific types of paroxysmal supraventricular tachycardias have been identified because of recognized inborn wiring errors. One such type is Wolfe-Parkinson-White syndrome (WPW syndrome). Precipitating factors may include caffeine or alcohol consumption, over-the-counter cold medications, electrolyte abnormalities, and excess thyroid hormone.

Atrial Fibrillation and Flutter

Atrial fibrillation and atrial flutter occur when all the muscle cells of the atrium start acting like pacemakers and start firing on their own. This barrage of electricity does not allow the atrium to have an organized contraction. Instead, it jiggles like a bowl of Jello. Many of these electrical signals are passed on erratically by the AV node to the ventricle, and it tries to respond as best as possible, leading to a rapid, irregular heart rate.

There are a couple of complications with this rhythm. Since the atrium does not get a unified electrical signal, it does not pump. This allows blood to settle in the crevices of the atrium, and blood clots can form. They, in turn, can break away and travel in the bloodstream to block the circulation at other sites, causing strokes and other vascular problems. Moreover, without the atrium beating, blood flows by gravity into the ventricles and approximately 15% of the heart's ability to pump blood to the rest of the body is lost, making the heart less efficient in meeting the needs of the body.

Ventricular Tachycardia and Fibrillation

Ventricular tachycardia (V Tach) is a potential life-threatening situation in which the ventricle starts firing quickly on its own. When people have coronary artery disease, the heart muscle can lack enough blood supply and become irritable. The electrical system doesn't tolerate this well and causes this abnormal heart rhythm. This rhythm may or may not allow the ventricle to beat in an organized way.

Ventricular fibrillation (V Fib) is not compatible with life since the ventricle has lost its ability to beat in an organized fashion, and the ventricle fibrillates or jiggles instead of beating, and the heart cannot pump blood to the body. This rhythm is what often causes sudden death after a heart attack.