Cardiac abnormalities discovered during long-term epilepsy monitoring

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American Journal of
Electroneurodiagnostic Technology
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Cardiac Abnormalities Discovered
during Long-Term Monitoring for
Epilepsy
Lisa A. Herder
a
a
2675 Brookdale Lane, Brooklyn Park, Minnesota
Published online: 03 Feb 2015.
To cite this article: Lisa A. Herder (2008) Cardiac Abnormalities Discovered during Long-Term
Monitoring for Epilepsy, American Journal of Electroneurodiagnostic Technology, 48:3, 192-198
To link to this article: http://dx.doi.org/10.1080/1086508X.2008.11079679
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Am J Electroneurodiagnostic Techno/
48:192-198, 2008
© ASET, Missouri
Cardiac Abnormalities Discovered during
Long-Term Monitoring for Epilepsy
Lisa A. Herder, R. EEG T., BS
2675 Brookdale Lane
Brooklyn Park, Minnesota
ABSTRACT. During routine EEGs, ambulatory EEGs, prolonged
EEGs in the intensive care unit, and long-term monitoring for epilepsy
(LTME), trained technologists record cerebral activity as well as
a basic electrocardiogram (ECG). The traditional use of this ECG
tracing is to differentiate ECG artifact from abnormal brain activity.
The pastfew years ofLTME have given rise to a greater appreciation of
the importance of ECG recording in patients undergoing continuous
video EEG monitoring. The ECG must be reviewed for abnormalities,
both ictal and non-ictal related. Although EEG technologists are not
formally trained in ECG, abnormalities on ECG may be observed that
could warrant further investigation through cardiology services. In
addition to treating the patient's neurological issues, it may be possible
to bring attention to previously undiagnosed cardiac problems that
could seriously threaten the patient's health.
KEY WORDS. Asystole, bradycardia, electrocardiogram (ECG),
ictal asystole, long-term monitoring for epilepsy (LTME), tachycardia.
INTRODUCTION
An electrocardiogram (ECG) is a recording of the electrical activity of the heart.
Electrodes are placed on the chest, arms, or legs in order to determine the amount of
electrical activity, the flow, and the direction of current moving through the heart.
Standard ECG recordings utilize 12 channels: 6 chest and 6 extremity (limb). The
chest leads, denoted V1-V6, are a "unipolar" recording. V 1 and V2 are located right
and left, respectively, of the sternum at the 4th intercostal space. V4, V5 , and V6 are at
Received for publication: March 4, 2008. Accepted for publication: April 9, 2008.
192

CARDIAC ABNORMALITIES DURING LTME 193
the 5th intercostal space at the midclavicular, anterior axillary, and midaxillary lines.
V3 is placed between V2 and V4 . The extremity leads are placed on the right and left
arms at the wrists, as well as the legs at the ankles. The right leg is a ground, while
the three remaining electrodes are referred to each other, as well unipolarly. These 12
channels provide multiple views of the cardiac activity (Goldberger 2006).
ECG can help detect arrhythmias, myocardial hypertrophy, ischemia, and con-
ductivity problems (Berkow et al. 1997). A normal adult heart rate is 60 to 100 beats
per minute (bpm) (Berkow et al. 1997). A fast heart rate, tachycardia, is more than
100 bpm. Bradycardia, a slow heart rate, is less than 60 bpm (Youngerman-Cole
2006). Asystole is the absence of a heart beat with no contraction of the heart
muscles (Stedman's Medical Dictionary 2006).
Observing the ECG channel can provide useful information regarding patients'
cardiac health. An excellent review ofheart anatomy and normal and abnormal cardiac
rhythms is "ECG for the EEG Technologist" by Margaret Hawkins, R. EEG/EP T.,
CNIM, American Journal of EEG Technology, 1992, Volume 32, pages 46 to 57.
In our LTME unit, ECG leads are placed on the chest, a few centimeters below the
clavicle. Two leads are placed, one on each side. The leads can also be placed on the
back at the scapula. Having a clean, prepped, and possibly shaved area for the leads
to adhere to is important to have an artifact free recording.
CASE STUDIES
Non-ictal Related Cardiac Abnormalities
Case One: A 29-year-old, right-handed male was admitted to the LTME unit with
a history of left temporal and right frontal cavernous hemangiomas. During his stay,
he was diagnosed with both right frontal and left temporal complex partial seizures.
While being monitored, the patient experienced a 22 second asystole unrelated to
electrographic ictal activity. At the onset of this event, his heart rate slowed to 60
bpm, and then quickly dropped to 48 bpm. He then entered a 22 second period of
asystole (Figure 1A). His resuming heart rate was 60 bpm, but within 32 seconds
became tachycardic at 180 bpm. During the period of asystole, the patient's EEG
drastically attenuated, making this a dramatic and easily detected event (Figure 1B).
The EEG technology staff alerted the attending physician to the asystole. This
resulted in pacemaker placement in less than 24 hours.
Case Two: An 81-year-old, left-handed female entered the EEG lab for a three
hour outpatient study. This patient had a history of atrial fibrillation and a left frontal
meningioma resection two years prior to this EEG. During the recording, the
patient's baseline heart rate was 60 to 70 bpm. The patient reported feeling a sudden
"spasm and head pain." At that time, she experienced a sinus rhythm pause for six
seconds (Figure 2). Her ECG resumed at 30 bpm for several minutes after the sinus

194 CARDIAC ABNORMALITIES DURING LTME
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FIG. 1 Case 1 -non-ictal related cardiac changes. (A) The patient's ECG (in the bottom
channel) changed from bradycardia to asystole. (8) After approximately 9 seconds of
asystole (ECG recorded in the bottom channel), the patient's EEG dramatically
attenuated.
pause. No significant EEG changes were noted. The physician recommended
a cardiology consultation, which resulted in a 30-day ECG monitor. A pacemaker
implantation was then recommended to the patient. She declined, stating she wanted
to "let nature take its course."

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FIG. 2. Case 2 - non-ictal related cardiac changes. Asystole (ECG recorded in the bottom
channel) occurs in an 81-year-old female during a routine outpatient EEG.
Ictal Related Cardiac Abnormalities
Case Three: A 30-year-old, left-handed male was admitted to the LTME unit
to evaluate possible seizure activity. The patient had a history of right sided
hemiparesis due to cerebral palsy. Prior to this admission, the patient had com-
plained of chest pain. During the admission, he was monitored by continuous video
EEG and remote continuous ECG telemetry. The patient experienced a possibly
secondarily generalized seizure, while his EEG electrodes were off for a hygiene
break. The ECG telemetry revealed that the patient became bradycardic and had
experienced a five second asystole. Later that day when the patient's electrodes were
attached, he experienced a simple partial seizure where the heart rate was reported to
drop from his baseline of 80 to 90 bpm to 20 bpm. He had a one second and then
a three second pause in his sinus rhythm. Following these episodes, a cardiology
consultation was ordered resulting in an echocardiogram that showed "mild con-
centric left ventricular hypertrophy," A pacemaker was recommended and placed
within three days of these cardiac events.

FIG. 3. Case 4- ictal related cardiac changes. During the seizure, the patient experiences
a 4 second asystole with one beat followed by 12 seconds of asystole (ECG recorded in the
bottom channel).
Case Four: A 32-year-old, left-handed female had undergone a 24-hour ECG
Holter monitor study which was reportedly normal. While being monitored on the
LTME unit, the patient experienced a complex partial seizure with a left temporal
onset. The patient's heart rate prior to the seizure was 108 bpm, but 23 seconds
after the electrographic seizure onset it dropped to 60 bpm. Four seconds later,
she experienced ictal asystole for a duration of 4 seconds, followed by a single
beat, and then returned to asystole for an additional 12 seconds (Figure 3). The
patient was referred to cardiac services for further testing and observation. This
ictal asystole event resulted in a pacemaker being placed within three days.
Case Five: A 60-year-old, right-handed male was admitted to the LTME unit,
with a history of a left frontal meningioma resected two years prior. Following the
surgery, the patient developed brain abscesses resulting in seizures. While
undergoing continuous video EEG monitoring, the patient experienced a second-
arily generalized seizure. Prior to the seizure, the patient had a normal sinus
rhythm of 60 bpm, then became tachycardic at 160 to 180 bpm as the seizure
progressed. Although the generalized tonic-clonic seizure caused artifact in the
ECG, it became clear that the patient experienced a seven second asystole as the
seizure began to resolve (Figure 4). Following the asystole, his heart rate became
bradycardic at 20 to 30 bpm, with a full return to baseline 60 seconds after seizure

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FIG. 4. Case 5 - ictal related cardiac changes. Asystole separated by one beat (ECG
recorded in the bottom channel) at the end of a secondarily generalized seizure.
cessation. A cardiology consultation was requested, resulting in further testing.
The patient had a normal cardiac magnetic resonance imaging (MRI) study, but an
abnormal echocardiogram. He had a pacemaker implanted two days after the ictal
asystole.
DISCUSSION
In order to correctly diagnose and treat patients, EEG results must be accurate and
comprehensive. Including ECG in standard EEG montages is essential to
differentiate between artifact and potentially abnormal brain activity. In addition
to utilizing ECG channels for artifact identification, the ECG can also provide other
useful information about the patient's baseline cardiac activity. LTME collects
multiple days of information which is used for comparative analysis. This may also
provide important information regarding cardiac health and disclose abnormalities
such as serious arrhythmias, including asystoles. These conditions warrant evalu-
ation and treatment. Identification and treatment of arrhythmias may prevent serious
morbidity or mortality.
Patients with epilepsy may suffer concomitant cardiac abnormalities. Temporal
lobe epilepsy has been associated with dysrhythmias, such as ictal asystole or
bradycardia (Schuele et al. 2007). Dysrhythmias, such as bradycardia and
tachycardia, were induced in rats by stimulation of the insula. Insular stimulation

in humans has also created a similar effect. Electrical stimulation of the frontal lobe
and temporal limbic area in humans has also caused cardiac abnormalities, including
asystole (So and Sperling 2007).
As seizures are observed and reviewed, attention to the ECG is essential. If ictal
asystole or bradycardia is detected, the patient should receive further cardiac testing.
Some physicians feel that a 5 to lO second asystole justifies pacemaker implantation
(So and Sperling 2007). A 2007 database search performed by Schuele et al. (2007)
found that 0.27% of 6,825 epilepsy patients experienced ictal asystole. Eight of these
patients had temporal lobe epilepsy, while two had extratemporallobe epilepsy.
CONCLUSION
Although most electroneurodiagnostic technologists are not formally trained in
ECG analysis, gross abnormalities should be recognized in the patients' ECG
recordings. Diligent monitoring and reviewing of EEG is essential in our neuro-
diagnostic evaluation. The same diligence should be applied when reviewing ECG,
while keeping in mind that patients with epilepsy may be prone to ictal asystole and
ictal bradycardia. Along with ictal related cardiac problems, patients may have
previously undiagnosed cardiac issues unrelated to seizure activity. Electro-
neurodiagnostic technologists must be thorough in reviewing all data, including
ECG, in order to fully serve the patients' healthcare needs.
ACKNOWLEDGEMENTS
I would like to thank the following staff of MINCEP Epilepsy Care: James
White, M.D., Thaddeus Walczak, M.D., David Hamley, R.N., and the Clinical
Neurophysiological Diagnostic staff for their assistance and support.
REFERENCES
Berkow R, Beers MH, Fletcher AI. (Editors). The Merck manual of medical information: home
edition. New York: Simon and Schuster; 1997. p. 77-83.
Goldberger AL. Clinical electrocardiography: a simplified approach. 7th edition. Philadelphia:
Mosby Elsevier; 2006. p. 21-29.
Hawkins M. ECG for the EEG technologist. Am I EEG Techno! 1992; 32(1):46--57.
Schuele SU, Bermeo AC, Alexopoulos AV, Locatelli ER, Burgess RC, Dinner DS, Foldvary-
Schaefer N. Video-electrographic and clinical features in patients with ictal asystole.
Neurology 2007; 69(5):434-41.
So NK, Sperling MR. Ictal asystole and SUDEP. Neurology 2007; 69(5):423-24.
Stedman's Medical Dictionary. 27th Edition. 2003. On the Internet at http://www.emedicine.com/
asp/dictionary.asp?keyword=asystole Accessed December 2007.
Youngerman-Cole S. Electrocardiogram. Updated April 21, 2006. On the Internet at http://
www.webmd.com/heart-disease/electrocardiogram Accessed December 2007.

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