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Paper text:
a 59-year - old woman was referred to our neurointerventional service for the embolization of an incidentally - found a right aca a1 segment aneurysm ( fig .
, we attempted to insert the tip of the microcatheter ( excelsior sl10 ; target therapeutics / boston scientific , natick , ma , u.s.a . ) into the aneurysm sac . even using various steam - shaped microcatheter tips , it was very difficult to stably position the tip .
after steam - shaping the tip into an " s - shape " , we were able to insert the microcatheter tip into the sac . during insertion of the framing coil , however , the tip of the microcatheter was kicked back , and the procedure was aborted after more than 90 minutes . a 52-year - old woman with an unruptured lesion
microcatheter positioning was successful using a steam - shaped microcatheter tip at an obtuse angle .
due to its instability , however , compact packing of the aneurysm was not possible ( fig .
we intentionally steam - shaped the tip of the microcatheter ( excelsior sl10 ) into a " z - shape " with a straight distal segment longer than that of an " s - shaped " tip ( fig .
we were able to advance the microcatheter tip from the terminal ica bifurcation into the aneurysm sac without any hindrance by the angle between the ica and aca a1 segment ( fig .
we tried to use the simple " z - shaped " microcatheter tip described for patient 3 .
however , the initial attempt was unsuccessful because of the rather higher position of the aneurysm sac relative to the main axis of the terminal segment of the ica , as shown on a lateral view ( fig .
we modified the shape of the tip to correspond to the main direction of the aneurysm sac ( fig .
a 59-year - old woman was referred to our neurointerventional service for the embolization of an incidentally - found a right aca a1 segment aneurysm ( fig .
, we attempted to insert the tip of the microcatheter ( excelsior sl10 ; target therapeutics / boston scientific , natick , ma , u.s.a . ) into the aneurysm sac . even using various steam - shaped microcatheter tips , it was very difficult to stably position the tip .
after steam - shaping the tip into an " s - shape " , we were able to insert the microcatheter tip into the sac . during insertion of the framing coil , however , the tip of the microcatheter was kicked back , and the procedure was aborted after more than 90 minutes .
a 52-year - old woman with an unruptured lesion was referred to us for treatment .
microcatheter positioning was successful using a steam - shaped microcatheter tip at an obtuse angle .
due to its instability , however , compact packing of the aneurysm was not possible ( fig .
we intentionally steam - shaped the tip of the microcatheter ( excelsior sl10 ) into a " z - shape " with a straight distal segment longer than that of an " s - shaped " tip ( fig .
we were able to advance the microcatheter tip from the terminal ica bifurcation into the aneurysm sac without any hindrance by the angle between the ica and aca a1 segment ( fig .
we tried to use the simple " z - shaped " microcatheter tip described for patient 3 .
however , the initial attempt was unsuccessful because of the rather higher position of the aneurysm sac relative to the main axis of the terminal segment of the ica , as shown on a lateral view ( fig .
we modified the shape of the tip to correspond to the main direction of the aneurysm sac ( fig .
intra - saccular placement of a microcatheter and stable coil placement are frequently difficult for aneurysms located at the proximal a1 segment of the aca , as we experienced in patients 1 and 2 .
our experience with these two patients motivated us to improve our microcatheter navigation and shaping skills .
the shapability , durability of the shape , and luminal changes in microcatheters have been evaluated in - vitro , and the adaptability of several microcatheter shapes to paraclinoid aneurysms has been assessed clinically [ 3 , 4 ] .
several microcatheter shapes adapted to the direction of an aneurysm have been found suitable for paraclinoid aneurysms , include s - shaped , pigtail - shaped , and other shapes .
however , shaping a microcatheter tip in accordance with the geometry of the parent artery and aneurysm dome was not successful in patients 1 and 2 . even after successfully positioning the microcatheter tip , it was not able to insert the coil due to early kick - back of the microcatheter tip .
our experiences with patients 1 and 2 suggested that a longer distal shaped tip may be more successful .
that could be achieved by ignoring the angle between the terminal portion of the ica and the proximal portion of the a1 segment .
we found that the straight part of the microcatheter tip efficiently engaged the sac , while the proximal angles were helpful for the lateral positioning of the distal angle and the supportive action of the more proximal angle .
we eventually designed a " z - shaped " tip , which was more effective when it had a rather longer distal straight segment .
as we showed for patient 4 , the distal straight tip should be shaped according to the direction of the terminal segment of the ica on lateral projection .
if the terminal ica has a rather steep angle , the tip of the catheter could not be easily inserted into the aneurysm sac because of the angle . in this situation , a modified z shape with a slight superiorly directed tip
may be helpful . in conclusion , we found that a " z - shaped " microcatheter tip was helpful in achieving effective and secure microcatheter tip positioning for the embolization of proximal aca a1 segment aneurysms , which are rare but difficult to treat with the endovascular techniques .
embolization of an aneurysm at the proximal a1 segment of the anterior cerebral artery ( aca ) is technically challenging . 
 we treated four consecutive patients with unruptured aneurysms at the proximal portion of the a1 segment of the aca . 
 we tested various microcatheter tip shapes before we successfully embolized a lesion with a zigzag - shaped microcatheter tip , which was made by steam shaping . 
 the shape of this microcatheter tip resembled the letter " z " , had a relatively long distal straight segment and was helpful in prompt catheterization of the aneurysm sac and stable placement of the catheter and delivery of coils .