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Multifocal atrial tachycardia

Chaotic atrial tachycardia

Multifocal atrial tachycardia (MAT) is a rapid heart rate. It occurs when too many signals (electrical impulses) are sent from the upper heart (atria) to the lower heart (ventricles).

Causes

The human heart gives off electrical impulses, or signals, which tell it to beat. Normally, these signals begin in an area of the upper right chamber called the sinoatrial node (sinus node or SA node). This node is considered the heart's "natural pacemaker." It helps control the heartbeat. When the heart detects a signal, it contracts (or beats).

The normal heart rate in adults is 60 to 100 beats per minute. The normal heart rate is faster in children.

In MAT, many locations in the atria fire signals at the same time. Too many signals lead to a rapid heart rate. It most often ranges from 100 to 130 beats per minute or more in adults. The rapid heart rate may cause the heart to work too hard and not move blood efficiently. If the heartbeat is very fast, there is less time for the heart chamber to fill with blood between beats. Therefore, not enough blood is pumped to the brain and the rest of the body with each contraction.

MAT is most common in people age 50 and over. It is often seen in people with conditions that lower the amount of oxygen in the blood. These conditions include:

You may be at higher risk for MAT if you have:

When the heart rate is less than 100 beats per minute, the arrhythmia is called "wandering atrial pacemaker."

Symptoms

Some people may have no symptoms. When symptoms occur, they can include:

Other symptoms that can occur with this disease:

Exams and Tests

A physical exam shows a fast irregular heartbeat of over 100 beats per minute. Blood pressure is normal or low. There may be signs of poor circulation.

Tests to diagnose MAT include:

Heart monitors may be used to record the rapid heartbeat. These include:

  • 24-hour Holter monitor
  • Portable, long-term loop recorders that allow you to start recording if symptoms occur

If you are in the hospital, your heart rhythm will be monitored 24 hours a day, at least at first.

Treatment

If you have a condition that can lead to MAT, that condition should be treated first.

Treatment for MAT includes:

  • Improving blood oxygen levels
  • Giving magnesium or potassium through a vein
  • Stopping medicines, such as theophylline, which can increase heart rate
  • Taking medicines to slow the heart rate (if the heart rate is too fast), such as calcium channel blockers (verapamil, diltiazem) or beta-blockers

Outlook (Prognosis)

MAT can be controlled if the condition that causes the rapid heartbeat is treated and controlled.

Possible Complications

Complications may include:

When to Contact a Medical Professional

Contact your health care provider if:

  • You have a rapid or irregular heartbeat with other MAT symptoms
  • You have MAT and your symptoms get worse, do not improve with treatment, or you develop new symptoms

Prevention

To reduce the risk for developing MAT, treat the disorders that cause it right away.

Open References

References

Kalman JM, Sanders P. Supraventricular tachycardias. In: Libby P, Bonow RO, Mann DL, Tomaselli GF, Bhatt DL, Solomon SD, eds. Braunwald's Heart Disease: A Textbook of Cardiovascular Medicine. 12th ed. Philadelphia, PA: Elsevier; 2022:chap 65.

Zimetbaum P, Goldman L. Supraventricular ectopy and tachyarrhythmias. In: Goldman L, Cooney KA, eds. Goldman-Cecil Medicine. 27th ed. Philadelphia, PA: Elsevier; 2024:chap 52.

  • What makes your heart beat?

    Animation

    •  

    What makes your heart beat? - Animation

    Let’s take a closer look inside the heart. The yellow objects are not nerves. They’re actually specialized cardiac muscle cells in the walls of the heart. Their job is to send signals to the rest of the heart muscle and cause a contraction. Together, this group of cells is called the Cardiac conduction system. The main components of the Cardiac conduction system are the SA node, AV node, Bundle of His, Bundle branches, and Purkinje fibers. Let’s follow a signal through the contraction process. The SA node starts the sequence by causing the atrial muscles to contract. That’s why doctors sometimes call it the anatomical pacemaker. From there, the signal travels to the AV node, through the Bundle of His, down the Bundle branches, and through the Purkinje fibers, causing the ventricles to contract. This signal creates an electrical current that can be seen on a graph called an Electrocardiogram, or EKG. Doctors us an EKG as a way of seeing how well the Cardiac conduction system works. Any changes to the EKG can mean serious problems.

  • Heart - section through the middle

    Heart - section through the middle - illustration

    The interior of the heart is composed of valves, chambers, and associated vessels.

    Heart - section through the middle

    illustration

  • Heart - front view

    Heart - front view - illustration

    The external structures of the heart include the ventricles, atria, arteries and veins. Arteries carry blood away from the heart while veins carry blood into the heart. The vessels colored blue indicate the transport of blood with relatively low content of oxygen and high content of carbon dioxide. The vessels colored red indicate the transport of blood with relatively high content of oxygen and low content of carbon dioxide.

    Heart - front view

    illustration

  • Conduction system of the heart

    Conduction system of the heart - illustration

    The intrinsic conduction system sets the basic rhythm of the beating heart by generating impulses which stimulate the heart to contract.

    Conduction system of the heart

    illustration

  • What makes your heart beat?

    Animation

    •  

    What makes your heart beat? - Animation

    Let’s take a closer look inside the heart. The yellow objects are not nerves. They’re actually specialized cardiac muscle cells in the walls of the heart. Their job is to send signals to the rest of the heart muscle and cause a contraction. Together, this group of cells is called the Cardiac conduction system. The main components of the Cardiac conduction system are the SA node, AV node, Bundle of His, Bundle branches, and Purkinje fibers. Let’s follow a signal through the contraction process. The SA node starts the sequence by causing the atrial muscles to contract. That’s why doctors sometimes call it the anatomical pacemaker. From there, the signal travels to the AV node, through the Bundle of His, down the Bundle branches, and through the Purkinje fibers, causing the ventricles to contract. This signal creates an electrical current that can be seen on a graph called an Electrocardiogram, or EKG. Doctors us an EKG as a way of seeing how well the Cardiac conduction system works. Any changes to the EKG can mean serious problems.

  • Heart - section through the middle

    Heart - section through the middle - illustration

    The interior of the heart is composed of valves, chambers, and associated vessels.

    Heart - section through the middle

    illustration

  • Heart - front view

    Heart - front view - illustration

    The external structures of the heart include the ventricles, atria, arteries and veins. Arteries carry blood away from the heart while veins carry blood into the heart. The vessels colored blue indicate the transport of blood with relatively low content of oxygen and high content of carbon dioxide. The vessels colored red indicate the transport of blood with relatively high content of oxygen and low content of carbon dioxide.

    Heart - front view

    illustration

  • Conduction system of the heart

    Conduction system of the heart - illustration

    The intrinsic conduction system sets the basic rhythm of the beating heart by generating impulses which stimulate the heart to contract.

    Conduction system of the heart

    illustration

Tests for Multifocal atrial tachycardia

 
 

Review Date: 5/27/2024

Reviewed By: Michael A. Chen, MD, PhD, Associate Professor of Medicine, Division of Cardiology, Harborview Medical Center, University of Washington Medical School, Seattle, WA. Also reviewed by David C. Dugdale, MD, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.

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