How Cardiac Arrhythmias Are Diagnosed

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To diagnose a cardiac arrhythmia, the arrhythmia itself needs to be "captured" on some type of heart rhythm recording. Diagnosis can be easy, difficult, or somewhere in between.

If you have a chronic or persistent arrhythmia, then it's just a matter of recording an electrocardiogram (ECG) and documenting the presence and type of arrhythmia you are experiencing.

Unfortunately, cardiac arrhythmias are often episodic in nature, coming and going without warning. In these cases, your symptoms may occur as sporadic episodes, often lasting just a few seconds, making a random 12-second ECG unlikely to reveal the arrhythmia. Additional testing is necessary.

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Medical History/Physical Exam

If your healthcare provider deems your symptoms to be non-life-threatening, they will likely start with a physical exam, as well as a review of your symptoms and possible conditions that could be causing the arrhythmia.

For instance, if they suspect that a thyroid disorder or heart disease is causing your arrhythmia, you may be tested for these conditions. Additionally, you may have a heart monitoring test such as an electrocardiogram (ECG) or an echocardiogram.

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Diagnostic Tests

If your healthcare provider thinks you may be experiencing cardiac arrhythmia, the first question is whether it is likely to be life-threatening.

Warning Signs

Your healthcare provider will likely consider the possibility that you are having a potentially dangerous arrhythmia, such as ventricular tachycardia or heart block, if you have:

This is especially true if you have an underlying cardiac disease.

If this is the case, you will probably be placed on a cardiac monitor in the hospital until a firm diagnosis can be made and, if necessary, effective treatment is instituted.

Electrocardiogram

More typical symptoms of an arrhythmia such as palpitations, mild fatigue, or mild, transient dizziness, are unlikely to indicate a life-threatening arrhythmia and a more routine cardiac evaluation can be used.

Generally, this is accomplished by attempting to record an ECG during an episode of symptoms. With a basic ECG, you have electrodes connected to your chest that record the electrical activity of your heart, including when and for how long your heartbeats occur.

Holter Monitor

If your symptoms occur daily or almost daily, the best choice for diagnosing the cause may be to use a Holter monitor, a portable ECG device that continuously records your heart rhythm for a 24- to 48-hour period of time.

You may be asked to keep a careful diary, noting the precise times that episodes of symptoms occur. The diary can then be correlated with the rhythm recording to show whether symptoms are associated with a cardiac arrhythmia.

Event Monitor

If your symptoms occur less frequently than every day or every few days, or they happen very quickly, the best choice may be an event monitor, another type of portable ECG.

You attach it to your body when you're having symptoms and press a button to record your heart's electrical activity during that time. Some smartphones also have a version of this technology.

Patch Monitors

Another option if your symptoms occur less frequently is a patch monitor such as a Zio patch, an adhesive, long-term recording device that can store up to two weeks of continuous recordings of your heart rhythm and automatically detect and record any cardiac arrhythmias you may have.

SEEQ MT system, another option, can record and monitor you for up to 30 days.

The disadvantages of patch monitors are that they can be expensive (as they're not reusable) and it may take extra time to get your results. However, they are convenient, water-resistant, easy-to-use, and comfortable to wear.

Implantable Loop Recorder

If your symptoms are extremely infrequent, a small implantable heart rhythm recorder can be used for up to three years to continuously record your heart rhythm and pick up arrhythmias that shorter-term heart monitors may miss.

This device is implanted under your skin in your chest and may be especially helpful in pinpointing the cause of a stroke, if applicable.

Echocardiogram

An echocardiogram is a type of painless ultrasound that's used to look at the size and structure of your heart, as well as how it beats. You can have an echocardiogram while you're exercising or while you're resting.

The purpose of recording your heart rhythm during an episode of symptoms is to try to correlate your symptoms with a recording of your ECG at the time the symptoms are occurring.

Ideally, to make the diagnosis, the symptoms will start when the arrhythmia does and resolve when the arrhythmia stops. If such a pattern is seen, it is almost certain that the arrhythmia is producing the symptoms.

Often, however, people will report symptoms at times when the heart rhythm turns out to be entirely normal; or conversely, an arrhythmia will be recorded at a time when no symptoms are present.

Under these circumstances, it's likely that the symptoms you're experiencing are NOT due to an arrhythmia, and your healthcare provider should begin considering alternative explanations for your symptoms.

When Additional Testing Is Needed

If your healthcare provider doesn't find an arrhythmia at all on a heart-monitoring test, but still suspects you have one, they may try to trigger one using one of these tests.

Stress Test

Since some arrhythmias are triggered or made worse by exercise or exertion, your healthcare provider may do a stress test, which involves monitoring your heart while you work out on a stationary bike or a treadmill.

If there's a reason why you can't exercise, you may be given a heart-stimulating drug instead.

Tilt Table Test

If you've had fainting spells or syncope, your healthcare provider may want to do a tilt table test.

While you lie flat on a table, your heart activity and blood pressure are monitored. You may also be given an intravenous line (IV) in case you need medication.

The table is then tilted so that it's vertical as if you're standing up while your healthcare provider monitors any changes in your blood pressure and/or heart activity.

Electrophysiology Study (EPS)

If your arrhythmia is infrequent or your healthcare provider's having a hard time confirming it and thinks it may be life-threatening, they may do an electrophysiology study (EPS).

This is a special catheterization test in which electrode catheters are inserted into your heart to study the cardiac electrical system.

What to Expect

If your healthcare provider has referred you for an EPS, you will be brought to the electrophysiology laboratory where you will lie down on an examination table.

You will be given local anesthesia, and possibly a mild sedative, and then electrode catheters will be inserted into one or more of your blood vessels. The catheters are inserted either through a small incision or by means of a needle-stick, usually in your arm, groin, or neck. Most often two or three catheters are used, which may be inserted from more than one site.

Using fluoroscopy, which is similar to an X-ray, the catheters are advanced through the blood vessels and positioned in specific areas within your heart.

Once they're appropriately positioned, the electrode catheters are used to do two main tasks:

  1. Record the electrical signals generated by your heart
  2. Pace your heart: This is accomplished by sending tiny electrical signals through the electrode catheter.

By recording and pacing from strategic locations within your heart, most kinds of cardiac arrhythmias can be fully studied.

When the procedure is complete, the catheter(s) are removed. Bleeding is controlled by placing pressure on the catheterization site for 30 to 60 minutes.

What It Does

An EPS can help evaluate both bradycardias (slow heart arrhythmias) and tachycardias (rapid heart arrhythmias).

Tachycardias are assessed by using programmed pacing techniques to trigger the tachycardia. If tachycardias can be triggered during the EPS, the precise cause can usually be identified by studying the electrical signals recorded from the electrode catheters. Once this is accomplished, the appropriate therapy usually becomes clear.

Determining Treatment

There are a few ways an EPS can help you and your healthcare provider make treatment decisions.

Treatment options that may be considered based on the results of an EPS include: 

  • Insertion of a pacemaker: If the EPS confirms the presence of significant bradycardia, a permanent pacemaker can often be inserted during the same procedure.
  • Ablation: If supraventricular tachycardia (SVT) or certain forms of ventricular tachycardia (VT) are found, radiofrequency ablation is often the treatment of choice. The ablation procedure is usually carried out during the same procedure, immediately following the EPS.
  • Insertion of an implantable defibrillator: If rapid forms of VT and/or ventricular fibrillation (VF) are identified during the EPS, an implantable defibrillator is most often the treatment of choice. This device can now often be inserted in the EP laboratory, immediately following the EPS. In earlier years, the EPS was used to identify the best anti-arrhythmic drug for patients with VT or VF, but today it's known that no anti-arrhythmic drug is as effective as the implantable defibrillator in preventing sudden death from these arrhythmias.

Risks

The potential risks of having an EPS are similar to those of having a cardiac catheterization. These procedures are relatively safe, but because they are invasive procedures involving the heart, several complications are possible.

You should not have an EPS unless there is a reasonable likelihood that the information gained from the procedure will be of significant benefit.

Minor complications include:

  • Minor bleeding at the site of catheter insertion
  • Temporary heart rhythm disturbances caused by the catheter irritating the heart muscle
  • Ttemporary changes in blood pressure

More significant complications include perforation of the heart wall causing a life-threatening condition called cardiac tamponade, extensive bleeding, or, because potentially lethal arrhythmias are being induced, cardiac arrest.

The risk of dying during an EPS is less than 1%.

Frequently Asked Questions

  • What are the types of cardiac arrhythmias?

    Arrhythmias can be broadly classified by the effect they have on the heart. The heart can beat too fast, which is called tachycardia. Or it can beat too slowly, in what is called bradycardia. If the heart beats irregularly, this is called fibrillation.

  • Do genetics play a role in cardiac arrythmia?

    Yes, some types of cardiac arrhythmia, called arrhythmia syndromes, are inherited. These syndromes include long QT syndrome. If you have a family member with one of these syndromes, you have a 50% chance of inheriting it as well. However, how they manifest often varies from individual to individual in a family, suggesting other factors, such as lifestyle or environmental influences, can play a role. 

  • What type of doctor treats heart arrhythmias?

    Cardiologists—doctors who are heart specialists—treat heart arrhythmias and other common heart problems. An electrophysiologist is a cardiologist who has had extensive training in treating arrhythmias.

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8 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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