Advantages of LV-LP guided by Inner-Cath
LV-LP guided by Inner-Cath alone has some advantages leading to the high
success rate of LV-LP. First, an Inner-Cath can be easily and safely
cannulated into the CS regardless of various CS anatomies or size of
right atrium (9), especially when using a 5Fr steerable EP catheter (11)
as electrophysiologists are familiar with its manipulation. In fact,
mechanical injuries of the CS such as dissection and perforation were
more frequently observed in the Outer-Cath group. In addition, it is not
difficult to advance an Inner-Cath deep inside the target CS
tributaries, that may result in shortened procedure time and reduce
radiation exposure compared with the Outer-Cath group. Our method makes
it unnecessary to select from a variety of Outer-Cath with different
shapes and curves. Given the excellent success rate of LV-LP guided by
Inner-Cath alone, it appears that an Inner-Cath provides sufficient
backup force to deliver LV leads to the target veins in spite of the
varied anatomy of CS tributaries. Our results suggest that it is a
misconception that use of an Outer-Cath is always necessary to get
adequate backup force for LV lead delivery. Our study results also
showed that LV threshold was significantly lower in the Inner-Cath group
than that of the Outer-Cath group. We surmise that this was due to
Inner-Cath superiority to Outer-Cath in terms of enabling selection of
optimal CS tributary and LV lead placement site, especially in patients
with ICM in whom the LV pacing may be affected by scar location (21).
Second, peel-off of the Inner-Cath for removal from the CS may be easier
than that of the Outer-Cath. We often experience LV lead dislodgement
when peeling off the Outer-Cath, which is caused by a mismatch between
the position of the CS ostium or CS trunk and shape of the selected
Outer-Cath with different curves. Meanwhile, the LV lead is very
unlikely to become dislodged during peel-off of an Inner-Cath because it
has a simple shape without complex curves. Third, an Inner-Cath can be
repeatedly inserted through a smaller 7 Fr sheath in the subclavian vein
unlike the Outer-Cath that requires an 9Fr or 10Fr sheath. The use of a
smaller sheath has substantial advantages in terms of avoiding the risk
of unnecessary bleeding from the insertion site of the sheath and
interference from other sheaths in manipulating a guiding catheter,
especially in patients undergoing a CRT upgrade who may have subclavian
vein stenosis due to the adhesion of previously inserted leads to a
venous wall as shown in Figure 4.