<s>
Sinus	B-Algorithm
bradycardia	I-Algorithm
is	O
a	O
sinus	B-Algorithm
node	I-Algorithm
dysfunction	I-Algorithm
giving	O
a	O
heart	O
rate	O
that	O
is	O
lower	O
than	O
the	O
normal	O
60	O
–	O
100	O
beats	O
per	O
minute	O
(	O
bpm	O
)	O
in	O
humans	O
.	O
</s>
<s>
Bradycardia	B-Algorithm
is	O
generally	O
defined	O
to	O
be	O
a	O
heart	O
rate	O
of	O
under	O
60	O
bpm	O
.	O
</s>
<s>
The	O
slow	B-Algorithm
heart	I-Algorithm
rate	I-Algorithm
may	O
also	O
lead	O
to	O
atrial	O
,	O
junctional	O
,	O
or	O
ventricular	O
ectopic	O
rhythms	O
.	O
</s>
<s>
Bradycardia	B-Algorithm
is	O
not	O
necessarily	O
problematic	O
.	O
</s>
<s>
People	O
who	O
practice	O
sports	O
may	O
have	O
sinus	B-Algorithm
bradycardia	I-Algorithm
,	O
because	O
their	O
trained	O
hearts	O
can	O
pump	O
enough	O
blood	O
in	O
each	O
contraction	O
to	O
allow	O
a	O
low	O
resting	O
heart	O
rate	O
.	O
</s>
<s>
Sinus	B-Algorithm
bradycardia	I-Algorithm
can	O
also	O
be	O
an	O
adaptive	O
advantage	O
;	O
for	O
example	O
,	O
diving	O
seals	O
may	O
have	O
a	O
heart	O
rate	O
as	O
low	O
as	O
12	O
beats	O
per	O
minute	O
,	O
helping	O
them	O
to	O
conserve	O
oxygen	O
during	O
long	O
dives	O
.	O
</s>
<s>
Sinus	B-Algorithm
bradycardia	I-Algorithm
is	O
a	O
common	O
condition	O
found	O
in	O
both	O
healthy	O
individuals	O
and	O
those	O
who	O
are	O
considered	O
well-conditioned	O
athletes	O
.	O
</s>
<s>
Heart	O
rates	O
considered	O
bradycardic	B-Algorithm
vary	O
by	O
species	O
;	O
for	O
example	O
,	O
in	O
the	O
house	O
cat	O
,	O
a	O
rate	O
of	O
under	O
120	O
beats	O
per	O
minute	O
is	O
abnormal	O
.	O
</s>
<s>
Sinus	B-Algorithm
bradycardia	I-Algorithm
is	O
commonly	O
seen	O
in	O
normal	O
healthy	O
persons	O
and	O
athletes	O
in	O
the	O
absence	O
of	O
pathophysiological	O
diseases	O
or	O
conditions	O
.	O
</s>
<s>
Diagnosis	O
of	O
sinus	B-Algorithm
bradycardia	I-Algorithm
can	O
be	O
confirmed	O
by	O
an	O
electrocardiogram	B-Application
that	O
shows	O
the	O
following	O
characteristics	O
:	O
</s>
<s>
P	B-Algorithm
waves	I-Algorithm
:	O
Upright	O
,	O
consistent	O
,	O
and	O
normal	O
in	O
morphology	O
and	O
duration	O
.	O
</s>
<s>
PR	B-Algorithm
interval	I-Algorithm
:	O
Between	O
0.12	O
and	O
0.20	O
seconds	O
in	O
duration	O
.	O
</s>
<s>
QRS	B-Algorithm
complex	I-Algorithm
:	O
Less	O
than	O
0.12	O
seconds	O
in	O
width	O
,	O
and	O
consistent	O
in	O
morphology	O
.	O
</s>
<s>
Any	O
recent	O
changes	O
to	O
patient	O
's	O
medication	O
history	O
,	O
new	O
symptoms	O
such	O
as	O
chest	O
pain	O
,	O
shortness	O
of	O
breath	O
and	O
palpitations	O
,	O
family	O
history	O
of	O
sinus	B-Algorithm
bradycardia	I-Algorithm
,	O
physical	O
exam	O
that	O
reveals	O
cyanosis	O
,	O
peripheral	O
edema	O
,	O
altered	O
mental	O
status	O
,	O
dyspnea	O
,	O
rales	O
and	O
crackles	O
are	O
all	O
relevant	O
information	O
to	O
consider	O
for	O
differential	O
diagnosis	O
.	O
</s>
