Purpose: factors contributing to pressure transmission through thrombosed o
r sealed endoleaks have not been elucidated. The purpose of this investigat
ion was to create an ex-vivo model that mimics patent and sealed endoleaks
and that can quantitatively analyse the effects of length, diameter and thr
ombus on pressure transmission to the interior of the aneurysm sac.
Methods: in the ex-vivo model, endoleak channels (ELCs) of various lengths
(2 cm, 6 cm, 10 cm) and diameters (0.6 cm, 1.0 cm, 1.4 cm) were constructed
using polytetrafluoroethylene (PTFE) grafts and attached to an artificial
aneurysm sac. These ELCs were incorporated within a mock circulation made o
f rubber tubing connected to a pulsatile pump. Peak systolic pressure (PSP)
was recorded in the aneurysm sac, distal to each ELC. Subsequently the ELC
s were filled with human thrombus, and the pressure measurements repeated (
n=5). Data was evaluated by regression analysis.
Results: peak systolic pressure in the artificial circulation was maintaine
d at 150 mmHg. In the absence of thrombus pressure did not change across th
e ELC, regardless of its length or diameter. In the presence of organised t
hrombus, the pressure curves distal to the ELC were dampened, and the press
ure reduction was directly proportional to the length and inversely proport
ional to the diameter of the ELC. Regression analysis indicated statistical
significance.
Conclusions: in the absence of thrombosis, pressure transmitted via an ELC
to the aneurysm sac is unchanged regardless of its length or diameter. All
sealed endoleaks also transmit pressure. However, when an endoleak has thro
mbosed, pressure reduction is directly proportional to the length and inver
sely proportional to the diameter of its channel. This ex-vivo model sugges
ts that Type 2 endoleaks with longer channels and smaller diameters would d
erive a greater benefit from adjunctive manoeuvres (coil embolisation) that
hasten thrombosis. On the other hand, thrombosis of endoleaks with short a
nd wide channels (e.g. Type 1) may not result in substantial pressure reduc
tion within the aneurysm sac and a successful outcome.