By Marcello Cherchi, MD PhD
For patients
Here are answers to some of the most common questions about cardiac monitoring.
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What is this test? |
This test looks at the rhythm of your heart. |
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What is this test looking for? |
This test can check whether the heart is sometimes beating too fast, too slow, or irregularly. |
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Is this test experimental or investigational? |
This test is approved by the Food and Drug Administration. It is neither experimental nor investigational. |
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What happens during this test? |
This test is usually given by a cardiologist (heart doctor). The cardiologist, or cardiac nurse, will give you a small device that is connected to your chest by several electrical leads. There are different versions of this test. In one version you wear the device for 48 or 72 hours. In another version you wear the device for a month, and you press a button if you have an “event” (such as lightheadedness or an episode of disequilibrium). With either test, when you have an episode, you should write down the time and date, and a description of the event. |
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Is this test uncomfortable? |
The test is not uncomfortable. Some people find it awkward to wear the device. |
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How long does this test take? |
In one version of the test, you wear the device for 48 or 72 hours. In another version of the test, you wear the device for a month. |
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Do I have to prepare for this test? |
Usually a cardiologist (heart doctor) gives you this test. |
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Are there any special instructions for what to do after the test? |
After finishing this test, you return the device to the cardiologist (heart doctor), who will read the results and send you a report. |
For clinicians
Overview
Various cardiac arrhythmias can result in transiently reduced cardiac output, causing cerebral hypoperfusion, which in turn can manifest with symptoms of disequilibrium. Cardiac arrhythmias can sometimes be identified with cardiac monitoring strategies, such as a Holter monitor or cardiac event monitor. These devices are generally dispensed by cardiologists (and often require cardiology referral, depending on the institution) and interpreted by cardiologists. It is medically reasonable to consider exploring the possibility of a cardiac arrhythmia in a patient complaining of episodes of lightheadedness, in whom a thorough vestibular evaluation has revealed no clear cause. The indication is stronger if the patient has a known personal or family history of cardiac disease.
Introduction
Transient cerebral hypoperfusion often manifests as presyncope (lightheadedness), which some patients will perceive and describe as a disturbance of equilibrium (Susanto 2014). Cardiac arrhythmia is one mechanism of transient cerebral hypoperfusion that can manifest with lightheadedness or disequilibrium. It appears that in some cases, transient cerebral hypoperfusion can be experienced as a spinning sensation (Newman-Toker and Camargo 2006).
Physiology and neuroanatomy
Transient cerebral hypoperfusion can result from reduced cardiac output secondary to various cardiac arrhythmias. A bradyarrhythmia is an obvious candidate for this. During arrhythmias such as atrial fibrillation, or even some tachyarrhythmias, the cardiac pulse rate may be elevated, but the heart is pumping inefficiently, and thus the overall cardiac output still declines despite the elevated rate.
In an otoneurology practice, cardiac arrhythmias are probably a less common cardiovascular mechanism for disequilibrium than orthostatic intolerance, which may be detectable on bedside orthostatic testing or on formal tilt table testing, that we discuss elsewhere.
Equipment needed
The method used for detecting a cardiac arrhythmia depends on the clinical scenario.
For patients who consistently experience multiple episodes per day, a 48-hour or 72-hour Holter monitor (Gordon 1978) may be able to “capture” an event. A Holter monitor records cardiac activity continuously.
For patients whose episodes are less frequent, a longer period of monitoring may be required — typically 30 days. Cardiac event monitors are devices that work continuously but only store the last several minutes of data. When a patient experiences an event, they push a button to trigger permanently saving the most recent several minutes (usually plus the next few minutes), and the sample is stored and eventually sent for analysis.
For either method, a patient is usually instructed to maintain a symptom log, with the date and time of individual events. Later a cardiologist reviews the rhythm record and checks whether the reported symptoms match with an identifiable cardiac arrhythmia.
How to perform the test
Devices such as Holter monitors and cardiac event monitors are dispensed by cardiologists, and obtaining such a study usually requires referral to cardiology, depending on the institution.
What this test assesses
A Holter monitor and cardiac event monitor electrically record cardiac rhythm.
How to interpret the test results
The results from these cardiac tests are read and interpreted by cardiology.
Limitations
For patients whose episodes of disequilibrium are relatively rare, it may be difficult to “capture” an episode, even with prolonged cardiac monitoring.
Contraindications
There are no firm contraindications to cardiac monitoring.
Pitfalls
A common problem with Holter monitoring and cardiac monitoring is that patients do not log their symptoms. Failure to log symptoms with date and time makes it impossible for the interpreting cardiologist to determine whether an identified cardiac arrhythmia synchronizes with symptoms.
When is the test indicated
It is medically reasonable to consider exploring the possibility of a cardiac arrhythmia in a patient complaining of episodes of lightheadedness, in whom a thorough vestibular evaluation has revealed no clear cause. The indication is stronger if the patient has a known personal or family history of cardiac disease.
Diseases that may be diagnosed by this test
Cardiac monitoring can identify a broad range of cardiac arrhythmias. The specific diagnosis relies on interpretation by the reading cardiologist.
References
Gordon M (1978) Occult cardiac arrhythmias associated with falls and dizziness in the elderly: detection by Holter monitoring. J Am Geriatr Soc 26: 418-23. doi: 10.1111/j.1532-5415.1978.tb05390.x
Newman-Toker DE, Camargo CA, Jr. (2006) ‘Cardiogenic vertigo’–true vertigo as the presenting manifestation of primary cardiac disease. Nat Clin Pract Neurol 2: 167-72; quiz 173. doi: 10.1038/ncpneuro0125
Susanto M (2014) Dizziness: if not vertigo could it be cardiac disease? Aust Fam Physician 43: 264-9.
