Discussion
There are many reasons that make angiography catheter discount,
including vascular tortuosity,
vasospasm, abnormal ostial of coronary artery, unskilled manipulation,
excessive traction and rotation. Understanding the tortuosity of blood
vessels in advance, and avoiding excessive rotation of the catheter,
maintaining a guide wire in the catheter lumen can help us to prevent
catheter from looping.
Once the catheter was knotted, inadequate manipulation and excessive
traction can make catheter fracture or even artery
dissection[4, 5]. There were several methods to
retrieve catheter knot, such as gentle rotation of the catheter to the
opposite direction, advancement of a super stiff wire into the loop,
external fixation of the distal part of the catheter at the arm level
with a blood pressure cuff[6], snare delivery[7-9]. In catheter ablation procedure, steerable
sheath was also used to untie diagnostic decapolar catheter
knot[10].
When it was difficult to withdraw the knotted catheter, we can advance a
bigger cut guiding catheter outside the angiography catheter to
strengthen the supporting power and exchange the shape of angiography
catheter. Pushing the guiding catheter into the knot point and pulling
the angiography catheter gently at the same time can help us to withdraw
the knotted catheter. In our case, the internal diameter of 6 French EBU
guiding catheter was 1.8mm, which was bigger than the external diameter
of 5 French angiography catheter, which was 1.7mm, and make sure that
the guiding catheter can enclose the angiography catheter. According to
Aminian’s study[11], the length of guiding
catheter was between “Knotted point- Puncture point” distance and
“Knotted point- Cut point” distance, and the length of
exceeded-guiding catheter part of angiography catheter was too short to
fix, so that we make balloon and angiography catheter contact tightly
and as a result we prolong the length of exceeded-guiding catheter part
of angiography catheter sufficiently in order to facilitate the
procedure, which was a bright point of our case.