<s>
The	O
bundle	B-Algorithm
of	I-Algorithm
His	I-Algorithm
(	O
BH	O
)	O
or	O
His	B-Algorithm
bundle	I-Algorithm
(	O
HB	O
)	O
(	O
"	O
hiss	O
"	O
)	O
is	O
a	O
collection	O
of	O
heart	O
muscle	O
cells	O
specialized	O
for	O
electrical	O
conduction	B-Algorithm
.	O
</s>
<s>
As	O
part	O
of	O
the	O
electrical	B-Algorithm
conduction	I-Algorithm
system	I-Algorithm
of	I-Algorithm
the	I-Algorithm
heart	I-Algorithm
,	O
it	O
transmits	O
the	O
electrical	B-Algorithm
impulses	I-Algorithm
from	O
the	O
atrioventricular	O
node	O
(	O
located	O
between	O
the	O
atria	O
and	O
the	O
ventricles	O
)	O
to	O
the	O
point	O
of	O
the	O
apex	O
of	O
the	O
fascicular	O
branches	O
via	O
the	O
bundle	O
branches	O
.	O
</s>
<s>
The	O
fascicular	O
branches	O
then	O
lead	O
to	O
the	O
Purkinje	B-Algorithm
fibers	I-Algorithm
,	O
which	O
provide	O
electrical	O
conduction	B-Algorithm
to	O
the	O
ventricles	O
,	O
causing	O
the	O
cardiac	O
muscle	O
of	O
the	O
ventricles	O
to	O
contract	O
at	O
a	O
paced	O
interval	O
.	O
</s>
<s>
The	O
bundle	B-Algorithm
of	I-Algorithm
His	I-Algorithm
is	O
an	O
important	O
part	O
of	O
the	O
electrical	B-Algorithm
conduction	I-Algorithm
system	I-Algorithm
of	I-Algorithm
the	I-Algorithm
heart	I-Algorithm
,	O
as	O
it	O
transmits	O
impulses	B-Algorithm
from	O
the	O
atrioventricular	O
node	O
,	O
located	O
at	O
the	O
anterior-inferior	O
end	O
of	O
the	O
interatrial	O
septum	O
,	O
to	O
the	O
ventricles	O
of	O
the	O
heart	O
.	O
</s>
<s>
The	O
bundle	B-Algorithm
of	I-Algorithm
His	I-Algorithm
branches	O
into	O
the	O
left	O
and	O
the	O
right	O
bundle	O
branches	O
,	O
which	O
run	O
along	O
the	O
interventricular	O
septum	O
.	O
</s>
<s>
These	O
bundles	O
and	O
fascicles	O
give	O
rise	O
to	O
thin	O
filaments	O
known	O
as	O
Purkinje	B-Algorithm
fibers	I-Algorithm
.	O
</s>
<s>
The	O
ventricular	O
conduction	B-Algorithm
system	I-Algorithm
comprises	O
the	O
bundle	O
branches	O
and	O
the	O
Purkinje	O
networks	O
.	O
</s>
<s>
It	O
takes	O
about	O
0.03	O
–	O
0.04	O
seconds	O
for	O
the	O
impulse	O
to	O
travel	O
from	O
the	O
bundle	B-Algorithm
of	I-Algorithm
His	I-Algorithm
to	O
the	O
ventricular	O
muscle	O
.	O
</s>
<s>
Disorders	O
affecting	O
the	O
cardiomyocytes	O
that	O
make	O
up	O
the	O
electrical	B-Algorithm
conduction	I-Algorithm
system	I-Algorithm
of	I-Algorithm
the	I-Algorithm
heart	I-Algorithm
are	O
called	O
heart	B-Algorithm
blocks	I-Algorithm
.	O
</s>
<s>
Heart	B-Algorithm
blocks	I-Algorithm
are	O
separated	O
into	O
different	O
categories	O
based	O
on	O
the	O
location	O
of	O
the	O
cellular	O
damage	O
.	O
</s>
<s>
Damage	O
to	O
any	O
of	O
the	O
conducting	O
cells	O
in	O
or	O
below	O
the	O
bundle	B-Algorithm
of	I-Algorithm
His	I-Algorithm
is	O
collectively	O
referred	O
to	O
as	O
"	O
infra-Hisian	O
blocks	O
"	O
.	O
</s>
<s>
To	O
be	O
specific	O
,	O
blocks	O
that	O
occur	O
in	O
the	O
right	O
or	O
left	O
bundle	O
branches	O
are	O
called	O
"	O
bundle	B-Algorithm
branch	I-Algorithm
blocks	I-Algorithm
"	O
,	O
and	O
those	O
that	O
occur	O
in	O
either	O
the	O
left	O
anterior	O
or	O
the	O
left	O
posterior	O
fascicles	O
are	O
called	O
"	O
fascicular	O
blocks	O
"	O
,	O
or	O
"	O
hemiblocks	O
"	O
.	O
</s>
<s>
The	O
conditions	O
in	O
which	O
both	O
the	O
right	O
bundle	O
branch	O
and	O
either	O
the	O
left	O
anterior	O
fascicle	O
or	O
the	O
left	O
posterior	O
fascicle	O
are	O
blocked	O
are	O
collectively	O
referred	O
to	O
as	O
bifascicular	B-Algorithm
blocks	I-Algorithm
,	O
and	O
the	O
condition	O
in	O
which	O
the	O
right	O
bundle	O
branch	O
,	O
the	O
left	O
anterior	O
fascicle	O
,	O
and	O
the	O
left	O
posterior	O
fascicle	O
are	O
blocked	O
is	O
called	O
trifascicular	B-Algorithm
block	I-Algorithm
.	O
</s>
<s>
A	O
2000	O
study	O
found	O
that	O
direct	O
His	B-Algorithm
bundle	I-Algorithm
pacing	O
is	O
more	O
effective	O
in	O
producing	O
synchronized	O
ventricular	O
contraction	O
—	O
and	O
therefore	O
in	O
improving	O
cardiac	O
function	O
—	O
than	O
apical	O
pacing	O
.	O
</s>
