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Peripheral
Figure 1: Example of Complete and Partial Protection with an
than the pore size will not be filtered. In addition, it may be difficult to
Angioguard During Renal Artery Stenting
ensure that the filter device is completely opposed to the vessel wall. If
the device is not adequately opposed, embolised material may simply slip
past the device. Another potential disadvantage of these devices is that
A
the initial crossing profile is larger, and this may lead to increased
embolisation during initial deployment and difficulty with crossing a
stenosis without use of pre-dilatation. One technique to facilitate
crossing of the stenosis and filter deployment without pre-dilatation is
the use of a ‘buddy wire’. Even if pre-dilatation is required to deploy the
filter, there may still be a benefit, as subsequent procedural steps,
including stenting, are associated with embolisation.
14
In addition to device-specific advantages and disadvantages, there are
limitations to the use of any EPD. First, there may be an early bifurcation of
the main renal artery. This would prevent complete protection of the renal
B
parenchyma during the stenting procedure (see Figure 1). Whether partial
protection is beneficial has not been established. In some circumstances,
vessel tortuosity precludes safe deployment of an EPD. In addition, the
diameter of the renal artery in the ‘touchdown zone’ for the device may not
accommodate an EPD. Although a vessel being too small for EPD use
A: An Angioguard device is seen in place proximal to the first bifurcation of the main renal
artery, resulting in complete protection of the renal parencyma. B: An Angioguard is occurs less frequently – as is occasionally encountered during treatment of
deployed distal to the first bifurcation of the main renal artery, resulting in incomplete
protection of the renal parenchyma.
an accessory renal artery – it is not unusual for the artery to be in excess of
6mm, at which point use of some protection devices is precluded due to an
Table 1: Summary of Selected Reports of Embolic Protection
inability to achieve adequate apposition to the vessel wall.
Device Use in Renal Artery Stenting
Patients (n) EDP Device Outcome p
Finally, all EPDs are effective only after deployment, thus they do not help
Edwards et al.
16
2 Guardwire SCr: -0.1±0.2mg/dl 0.013
to protect the kidney from atheroembolism during initial engagement
EGFR: 5.8±8.8ml/min/1.73m
2
0.006
with a guide catheter, and certainly do not protect the contralateral kidney
Edwards et al.
17
26 Guardwire SCr: -0.3mg/dl <0.001 or other organ systems that may be affected by emboli liberated from the
eGFR: 6.6ml/min/1.73m
2
<0.001
abdominal aorta. In order to minimise embolic complications with initial
Holden et al.
18
63 Angioguard Renal function:
catheter engagement, a number of techniques are available, including the
FilterWire Improved 40%
‘telescoping catheter’ technique and the ‘no-touch’ technique.
27
Satbilised 57%
Unchanged decline 3%
Henry et al.
19
56 Guardwire No change in serum creatinine NS
The telescoping catheter technique uses a 5–6Fr diagnostic catheter to
Angioguard at up to three years of follow-up
initially engage the renal artery. A larger guide catheter is advanced in
FilterWire over the diagnostic catheter, which is then removed prior to performing
Hagspiel et al.
20
4 FilterWire Renal function:
the interventional procedure. Using the no-touch technique, a 0.035-inch
Improved 25%
J-tipped guidewire is advanced out of the guide catheter, in order to keep
Stabilised 25%
it away from the wall of the aorta. The guide catheter is then brought
Unchanged 25%
into proximity to the renal artery, and a 0.014-inch guidewire is directed
Worsened 25%
Holden et al.
21
37 Angioguard Renal function:
into the distal renal artery. The interventional procedure is then
Improved 38%
performed following removal of the 0.035-inch J-tipped wire.
27
In
Stabilised 57% addition, aggressive aspiration of the catheter with the removal of at least
Unchanged decline 5%
10ml of blood and subsequent flushing with heparinised saline prior to
angiography can help to protect against distal embolisation.
28
Angioguard device has been evaluated in a randomised trial compared
with the control of no EDP.
15
Clinical Reports of Embolic Protection Device
Use in Renal Stenting
The greatest potential advantage of distal filters is their ability to maintain The use of EPDs in renal artery stenting has been reported in several case
renal perfusion during the procedure. This eliminates the theoretical series.
16–24
The primary outcome measure has been the change in renal
concern of ischaemia induced by balloon occlusion. In addition, continuous function from baseline to follow-up, measured by serum creatinine
antegrade flow makes it easier for the operator to visualise each step of the and/or estimated glomerular filtration rate (eGFR). A summary of these
procedure, and this may also reduce total procedure time. Henry et al. results is shown in Table 1. Although these reports have suggested that
reported a mean time of filter deployment of 4.25 minutes, which was EPD may prevent deterioration of renal function following renal stenting,
shorter than the occlusion time with a distal occlusion balloon.
19
they are limited by the lack of a control group.
Potential disadvantages of distal filters include incomplete protection of The recently published RESIST trial
15
compared renal artery stenting with
the renal parenchyma from embolised material, as any particles smaller and without the use of the Angioguard short-tip EPDs. In the RESIST trial,
80 INTERVENTIONAL CARDIOLOGY
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