<s>
Sinus	B-Algorithm
tachycardia	I-Algorithm
is	O
an	O
elevated	O
sinus	O
rhythm	O
characterized	O
by	O
an	O
increase	O
in	O
the	O
rate	O
of	O
electrical	O
impulses	O
arising	O
from	O
the	O
sinoatrial	O
node	O
.	O
</s>
<s>
In	O
adults	O
,	O
sinus	B-Algorithm
tachycardia	I-Algorithm
is	O
defined	O
as	O
a	O
heart	O
rate	O
greater	O
than	O
100	O
beats	O
per	O
minute	O
(	O
bpm	O
)	O
.	O
</s>
<s>
Sinus	B-Algorithm
tachycardia	I-Algorithm
is	O
a	O
normal	O
response	O
to	O
physical	O
exercise	O
,	O
when	O
the	O
heart	O
rate	O
increases	O
to	O
meet	O
the	O
body	O
's	O
higher	O
demand	O
for	O
energy	O
and	O
oxygen	O
,	O
but	O
sinus	B-Algorithm
tachycardia	I-Algorithm
can	O
also	O
indicate	O
a	O
health	O
problem	O
.	O
</s>
<s>
Thus	O
,	O
sinus	B-Algorithm
tachycardia	I-Algorithm
is	O
a	O
medical	O
finding	O
that	O
can	O
be	O
either	O
physiological	O
or	O
pathological	O
.	O
</s>
<s>
Tachycardia	B-Application
is	O
often	O
asymptomatic	O
.	O
</s>
<s>
Sinus	B-Algorithm
tachycardia	I-Algorithm
accompanying	O
a	O
myocardial	O
infarction	O
may	O
be	O
indicative	O
of	O
cardiogenic	O
shock	O
.	O
</s>
<s>
Sinus	B-Algorithm
tachycardia	I-Algorithm
is	O
usually	O
a	O
response	O
to	O
physiological	O
stress	O
,	O
such	O
as	O
exercise	O
,	O
or	O
an	O
increased	O
sympathetic	O
tone	O
with	O
increased	O
catecholamine	O
release	O
,	O
such	O
as	O
stress	O
,	O
fright	O
,	O
flight	O
,	O
and	O
anger	O
.	O
</s>
<s>
Sinus	B-Algorithm
tachycardia	I-Algorithm
is	O
usually	O
apparent	O
on	O
an	O
ECG	B-Application
,	O
but	O
if	O
the	O
heart	O
rate	O
is	O
above	O
140	O
bpm	O
the	O
P	B-Algorithm
wave	I-Algorithm
may	O
be	O
difficult	O
to	O
distinguish	O
from	O
the	O
previous	O
T	B-Algorithm
wave	I-Algorithm
and	O
one	O
may	O
confuse	O
it	O
with	O
a	O
paroxysmal	B-Algorithm
supraventricular	I-Algorithm
tachycardia	I-Algorithm
or	O
atrial	O
flutter	O
with	O
a	O
2:1	O
block	O
.	O
</s>
<s>
P	B-Algorithm
waves	I-Algorithm
:	O
Upright	O
,	O
in	O
leads	O
I	O
,	O
II	O
and	O
aVL	O
,	O
and	O
negative	O
in	O
lead	O
aVR	O
;	O
</s>
<s>
In	O
inappropriate	B-Algorithm
sinus	I-Algorithm
tachycardia	I-Algorithm
(	O
also	O
known	O
as	O
chronic	O
nonparoxysmal	O
sinus	B-Algorithm
tachycardia	I-Algorithm
)	O
,	O
patients	O
have	O
an	O
elevated	O
resting	O
heart	O
rate	O
and/or	O
exaggerated	O
heart	O
rate	O
in	O
response	O
to	O
exercise	O
.	O
</s>
<s>
These	O
patients	O
have	O
no	O
apparent	O
heart	O
disease	O
or	O
other	O
causes	O
of	O
sinus	B-Algorithm
tachycardia	I-Algorithm
.	O
</s>
<s>
Usually	O
,	O
in	O
women	O
with	O
no	O
heart	O
problems	O
,	O
this	O
syndrome	O
is	O
characterized	O
by	O
normal	O
resting	O
heart	O
rate	O
but	O
exaggerated	O
postural	O
sinus	B-Algorithm
tachycardia	I-Algorithm
with	O
or	O
without	O
orthostatic	O
hypotension	O
.	O
</s>
<s>
Upon	O
exertion	O
,	O
sinus	B-Algorithm
tachycardia	I-Algorithm
can	O
be	O
seen	O
in	O
some	O
inborn	O
errors	O
of	O
metabolism	O
that	O
result	O
in	O
metabolic	O
myopathies	O
,	O
such	O
as	O
McArdle	O
Disease	O
(	O
GSD-V	O
)	O
.	O
</s>
<s>
This	O
energy	O
shortage	O
in	O
muscle	O
cells	O
causes	O
an	O
inappropriate	O
rapid	B-Application
heart	I-Application
rate	I-Application
in	O
response	O
to	O
exercise	O
.	O
</s>
<s>
As	O
skeletal	O
muscle	O
relies	O
predominantly	O
on	O
glycogenolysis	O
for	O
the	O
first	O
few	O
minutes	O
as	O
it	O
transitions	O
from	O
rest	O
to	O
activity	O
,	O
as	O
well	O
as	O
throughout	O
high-intensity	O
aerobic	O
activity	O
and	O
all	O
anaerobic	O
activity	O
,	O
individuals	O
with	O
glycogenoses	O
experience	O
during	O
exercise	O
:	O
sinus	B-Algorithm
tachycardia	I-Algorithm
,	O
tachypnea	O
,	O
muscle	O
fatigue	O
and	O
pain	O
,	O
during	O
the	O
aforementioned	O
activities	O
and	O
time	O
frames	O
.	O
</s>
<s>
The	O
inappropriate	O
rapid	B-Application
heart	I-Application
rate	I-Application
in	O
response	O
to	O
exercise	O
may	O
be	O
misdiagnosed	O
as	O
inappropriate	B-Algorithm
sinus	I-Algorithm
tachycardia	I-Algorithm
(	O
which	O
is	O
a	O
diagnosis	O
of	O
exclusion	O
)	O
.	O
</s>
<s>
Treatment	O
for	O
physiologic	O
sinus	B-Algorithm
tachycardia	I-Algorithm
involves	O
treating	O
the	O
underlying	O
causes	O
of	O
the	O
tachycardia	B-Application
response	O
.	O
</s>
<s>
Beta	O
blockers	O
may	O
be	O
used	O
to	O
decrease	O
tachycardia	B-Application
in	O
patients	O
with	O
certain	O
conditions	O
,	O
such	O
as	O
ischemic	O
heart	O
disease	O
and	O
rate-related	O
angina	O
.	O
</s>
<s>
In	O
patients	O
with	O
inappropriate	B-Algorithm
sinus	I-Algorithm
tachycardia	I-Algorithm
,	O
careful	O
titration	O
of	O
beta-blockers	O
,	O
salt	O
loading	O
,	O
and	O
hydration	O
typically	O
reduce	O
symptoms	O
.	O
</s>
<s>
Sinus	B-Algorithm
tachycardia	I-Algorithm
can	O
present	O
in	O
more	O
than	O
a	O
third	O
of	O
the	O
patients	O
with	O
AMI	O
but	O
this	O
usually	O
decreases	O
over	O
time	O
.	O
</s>
<s>
Patients	O
with	O
sustained	O
sinus	B-Algorithm
tachycardia	I-Algorithm
reflects	O
a	O
larger	O
infarct	O
that	O
are	O
more	O
anterior	O
with	O
prominent	O
left	O
ventricular	O
dysfunction	O
,	O
associated	O
with	O
high	O
mortality	O
and	O
morbidity	O
.	O
</s>
<s>
Tachycardia	B-Application
in	O
the	O
presence	O
of	O
AMI	O
can	O
reduce	O
coronary	O
blood	O
flow	O
and	O
increase	O
myocardial	O
oxygen	O
demand	O
,	O
aggravating	O
the	O
situation	O
.	O
</s>
