<s>
The	O
hexaxial	B-Algorithm
reference	I-Algorithm
system	I-Algorithm
,	O
better	O
known	O
as	O
the	O
Cabrera	B-Algorithm
system	I-Algorithm
,	O
is	O
a	O
convention	O
to	O
present	O
the	O
extremity	O
leads	O
of	O
the	O
12	B-Application
lead	I-Application
electrocardiogram	B-Application
,	O
that	O
provides	O
an	O
illustrative	O
logical	O
sequence	O
that	O
helps	O
interpretation	O
of	O
the	O
ECG	B-Application
,	O
especially	O
to	O
determine	O
the	O
heart	O
's	O
electrical	O
axis	O
in	O
the	O
frontal	O
plane	O
.	O
</s>
<s>
The	O
most	O
practical	O
way	O
of	O
using	O
this	O
is	O
by	O
arranging	O
extremity	O
leads	O
according	O
to	O
the	O
Cabrera	B-Algorithm
system	I-Algorithm
,	O
reversing	O
polarity	O
of	O
lead	O
aVR	O
and	O
presenting	O
ECG	B-Application
complexes	O
in	O
the	O
order	O
(	O
aVL	O
,	O
I	O
,	O
-aVR	O
,	O
II	O
,	O
aVF	O
,	O
III	O
)	O
.	O
</s>
<s>
Then	O
determine	O
the	O
direction	O
the	O
maximal	O
ECG	B-Application
vector	O
is	O
"	O
pointing	O
"	O
,	O
i.e.	O
</s>
<s>
An	O
alternative	O
use	O
is	O
to	O
locate	O
the	O
most	O
isoelectric	O
(	O
or	O
equiphasic	O
)	O
lead	O
(	O
I	O
,	O
II	O
,	O
III	O
,	O
aVR	O
,	O
aVL	O
,	O
or	O
aVF	O
)	O
on	O
a	O
diagnostic	O
quality	O
ECG	B-Application
with	O
proper	O
lead	O
placement	O
.	O
</s>
<s>
Then	O
find	O
the	O
corresponding	O
spoke	O
on	O
the	O
hexaxial	B-Algorithm
reference	I-Algorithm
system	I-Algorithm
.	O
</s>
<s>
To	O
determine	O
which	O
numerical	O
value	O
should	O
be	O
used	O
,	O
observe	O
the	O
polarity	O
of	O
the	O
perpendicular	O
lead	O
on	O
the	O
ECG	B-Application
.	O
</s>
<s>
For	O
example	O
,	O
if	O
the	O
most	O
isoelectric	O
(	O
or	O
equiphasic	O
)	O
lead	O
is	O
aVL	O
,	O
the	O
perpendicular	O
lead	O
on	O
the	O
hexaxial	B-Algorithm
reference	I-Algorithm
system	I-Algorithm
is	O
lead	O
II	O
.	O
</s>
<s>
If	O
lead	O
II	O
is	O
positively	O
deflected	O
on	O
the	O
ECG	B-Application
,	O
the	O
heart	O
's	O
electrical	O
axis	O
in	O
the	O
frontal	O
plane	O
will	O
be	O
approximately	O
+60°	O
.	O
</s>
