<s>
Clinical	B-Algorithm
cardiac	I-Algorithm
electrophysiology	I-Algorithm
(	O
also	O
referred	O
to	O
as	O
cardiac	B-Algorithm
electrophysiology	I-Algorithm
,	O
arrhythmia	B-Application
services	O
,	O
or	O
electrophysiology	B-Algorithm
)	O
,	O
is	O
a	O
branch	O
of	O
the	O
medical	O
specialty	O
of	O
cardiology	O
and	O
is	O
concerned	O
with	O
the	O
study	O
and	O
treatment	O
of	O
rhythm	B-Application
disorders	I-Application
of	O
the	O
heart	O
.	O
</s>
<s>
Cardiologists	O
with	O
expertise	O
in	O
this	O
area	O
are	O
usually	O
referred	O
to	O
as	O
electrophysiologists	B-Application
.	O
</s>
<s>
Electrophysiologists	B-Application
are	O
trained	O
in	O
the	O
mechanism	O
,	O
function	O
,	O
and	O
performance	O
of	O
the	O
electrical	O
activities	O
of	O
the	O
heart	O
.	O
</s>
<s>
Electrophysiologists	B-Application
work	O
closely	O
with	O
other	O
cardiologists	O
and	O
cardiac	O
surgeons	O
to	O
assist	O
or	O
guide	O
therapy	O
for	O
heart	O
rhythm	O
disturbances	O
(	O
arrhythmias	B-Application
)	O
.	O
</s>
<s>
They	O
are	O
trained	O
to	O
perform	O
interventional	O
and	O
surgical	O
procedures	O
to	O
treat	O
cardiac	B-Application
arrhythmia	I-Application
.	O
</s>
<s>
The	O
training	O
required	O
to	O
become	O
an	O
electrophysiologist	B-Application
is	O
lengthy	O
and	O
requires	O
eight	O
years	O
after	O
medical	O
school	O
(	O
in	O
the	O
U.S.	O
)	O
,	O
entailing	O
three	O
years	O
of	O
internal	O
medicine	O
residency	O
,	O
three	O
years	O
of	O
clinical	O
cardiology	O
fellowship	O
,	O
and	O
two	O
years	O
of	O
clinical	B-Algorithm
cardiac	I-Algorithm
electrophysiology	I-Algorithm
.	O
</s>
<s>
This	O
is	O
necessary	O
due	O
to	O
the	O
significant	O
complexity	O
of	O
patients	O
that	O
electrophysiologists	B-Application
usually	O
treat	O
,	O
the	O
constant	O
advances	O
in	O
methods	O
and	O
equipment	O
used	O
in	O
their	O
daily	O
practice	O
,	O
making	O
the	O
field	O
of	O
electrophysiology	B-Algorithm
one	O
of	O
the	O
most	O
demanding	O
subspecialties	O
of	O
modern	O
medicine	O
.	O
</s>
<s>
An	O
electrophysiology	B-Algorithm
study	I-Algorithm
is	O
any	O
of	O
a	O
number	O
of	O
invasive	O
(	O
intracardiac	O
)	O
and	O
non-invasive	O
recording	O
of	O
spontaneous	O
electrical	O
activity	O
,	O
as	O
well	O
as	O
of	O
cardiac	O
responses	O
to	O
programmed	B-Algorithm
electrical	I-Algorithm
stimulation	I-Algorithm
.	O
</s>
<s>
These	O
studies	O
are	O
performed	O
to	O
assess	O
arrhythmias	B-Application
,	O
elucidate	O
symptoms	O
,	O
evaluate	O
abnormal	O
electrocardiograms	B-Application
,	O
assess	O
risk	O
of	O
developing	O
arrhythmias	B-Application
in	O
the	O
future	O
,	O
and	O
design	O
treatment	O
.	O
</s>
<s>
In	O
addition	O
to	O
diagnostic	O
testing	O
of	O
the	O
electrical	O
properties	O
of	O
the	O
heart	O
,	O
electrophysiologists	B-Application
are	O
trained	O
in	O
therapeutic	O
and	O
surgical	O
methods	O
to	O
treat	O
many	O
of	O
the	O
rhythm	O
disturbances	O
of	O
the	O
heart	O
.	O
</s>
<s>
Therapeutic	O
modalities	O
employed	O
in	O
this	O
field	O
include	O
antiarrhythmic	B-Algorithm
drug	I-Algorithm
therapy	O
and	O
surgical	O
implantation	O
of	O
pacemakers	B-Algorithm
and	O
implantable	O
cardioverter-defibrillators	O
.	O
</s>
<s>
Ambulatory	O
electrocardiographic	B-Application
monitoring	O
-	O
Holter	O
and	O
event	O
monitor	O
recording	O
and	O
interpretation	O
;	O
</s>
<s>
Signal-averaged	B-Algorithm
electrocardiogram	I-Algorithm
(	O
SAECG	B-Algorithm
)	O
interpretation	O
,	O
also	O
referred	O
to	O
as	O
"	O
late	B-Algorithm
potentials	I-Algorithm
"	O
reading	O
;	O
</s>
<s>
Electrophysiology	B-Algorithm
study	I-Algorithm
(	O
EPS	O
)	O
consists	O
in	O
the	O
insertion	O
of	O
pacing	O
and	O
recording	O
electrodes	O
either	O
in	O
the	O
esophagus	O
(	O
intra-esophageal	O
EPS	O
)	O
or	O
,	O
through	O
blood	O
vessels	O
,	O
directly	O
into	O
the	O
heart	O
chambers	O
(	O
intra-cardiac	O
EPS	O
)	O
in	O
order	O
to	O
measure	O
electrical	O
properties	O
of	O
the	O
heart	O
and	O
,	O
in	O
the	O
case	O
of	O
intra-cardiac	O
EPS	O
,	O
to	O
electrically	O
stimulate	O
it	O
in	O
the	O
attempt	O
to	O
induce	O
arrhythmias	B-Application
for	O
diagnostic	O
purposes	O
(	O
"	O
programmed	B-Algorithm
electrical	I-Algorithm
stimulation	I-Algorithm
"	O
)	O
.	O
</s>
<s>
Initial	O
administration	O
and	O
monitoring	O
of	O
the	O
effect	O
of	O
drugs	O
for	O
treatment	O
of	O
heart	O
rhythm	B-Application
disorders	I-Application
.	O
</s>
<s>
Electrophysiologists	B-Application
are	O
often	O
involved	O
when	O
severe	O
or	O
life-threatening	O
arrhythmias	B-Application
are	O
being	O
treated	O
,	O
or	O
when	O
multiple	O
drugs	O
must	O
be	O
used	O
to	O
treat	O
an	O
arrhythmia	B-Application
.	O
</s>
<s>
Antiarrhythmic	B-Algorithm
agents	I-Algorithm
are	O
commonly	O
used	O
to	O
try	O
to	O
control	O
rhythms	O
.	O
</s>
<s>
Ablation	O
therapy	O
-	O
Catheter	O
based	O
ablation	O
of	O
lesions	O
in	O
the	O
heart	O
(	O
with	O
radiofrequency	O
energy	O
,	O
cryotherapy	O
(	O
destructive	O
freezing	O
)	O
,	O
microwave	O
,	O
or	O
ultrasound	O
energy	O
)	O
to	O
cure	O
or	O
control	O
arrhythmias	B-Application
(	O
see	O
radiofrequency	O
ablation	O
)	O
.	O
</s>
<s>
Ablation	O
is	O
usually	O
performed	O
during	O
the	O
same	O
procedure	O
as	O
the	O
electrophysiology	B-Algorithm
study	I-Algorithm
during	O
which	O
arrhythmias	B-Application
are	O
attempted	O
to	O
be	O
induced	O
as	O
well	O
as	O
elucidating	O
the	O
mechanism	O
of	O
the	O
arrhythmia	B-Application
for	O
which	O
ablation	O
therapy	O
is	O
sought	O
.	O
</s>
<s>
"	O
Non-complex	O
"	O
ablations	O
include	O
ablation	O
for	O
arrhythmias	B-Application
such	O
as	O
:	O
AV	B-Algorithm
nodal	I-Algorithm
reentrant	I-Algorithm
tachycardia	I-Algorithm
,	O
accessory	O
pathway	O
mediated	O
tachycardia	O
,	O
CTI-dependent	O
atrial	O
flutter	O
.	O
</s>
<s>
These	O
procedures	O
are	O
usually	O
performed	O
using	O
intracardiac	O
catheters	O
(	O
as	O
are	O
used	O
during	O
an	O
electrophysiology	B-Algorithm
study	I-Algorithm
)	O
,	O
fluoroscopy	O
(	O
a	O
real-time	O
X-ray	O
camera	O
)	O
,	O
and	O
electrical	O
recordings	O
from	O
the	O
inside	O
of	O
the	O
heart	O
.	O
</s>
<s>
"	O
Complex	O
"	O
ablations	O
include	O
ablation	O
for	O
arrhythmias	B-Application
such	O
as	O
multifocal	B-Algorithm
atrial	I-Algorithm
tachycardia	I-Algorithm
,	O
atrial	B-Application
fibrillation	I-Application
,	O
and	O
ventricular	B-Application
tachycardia	I-Application
.	O
</s>
