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three patients were admitted to our hospital with neurological deficits within 3 hours from symptom onset .
they all presented with a high national institutes of health stroke scale ( nihss ) score and brain computed tomography ( ct ) that showed no hemorrhagic density .
intravenous tissue plasminogen activator was administered , and ct angiography ( cta ) and diffusion - weighted magnetic resonance imagining ( dwi ) were subsequently performed . after obtaining informed consent , mechanical thrombectomy was conducted under conscious sedation .
a 47-year - old female patient was admitted to our hospital with left limb weakness .
she had no prior medical history of hypertension , diabetes , or atrial f ibrillation .
the initial neurologic examination demonstrated a drowsy state , left hemiparesis , and dysarthria with a nihss score of 8 .
her vital signs were stable with a blood pressure of 170/90 mmhg and a serum glucose level of 71 mg / dl .
non - enhanced brain ct revealed no hemorrhagic density and cta showed an occlusion in the distal basilar artery ( fig .
( chaperon , microvention , tustin , ca , usa ) was introduced from the right femoral artery to the distal v2 segment in the left vertebral artery .
a dac ( navien 058 ; ev3/covidien , irvine , ca , usa ) coaxilally with a .021-inch microcatheter ( prowler select plus ; cordis , miami , fl , usa ) and a .014-inch microguidewire ( synchro-14 ; stryker , kalamazoo , mi , usa ) was advanced to the proximal end of the occluded segment ( fig .
after retraction of the microcatheter and microguidewire , direct aspiration with the dac was performed using a 50-ml syringe .
the retrieved catheter showed a large thrombus wedged within it , and complete reperfusion was achieved ( fig .
a 71-year - old male patient with a medical history of hypertension and hyperlipidemia was admitted to our hospital with right limb weakness . on arrival ,
his blood pressure was 115/65 mmhg , his blood sugar level was 113 mg / dl , and electrocardiography showed a sinus rhythm .
initial neurologic examination revealed right facial palsy , global aphasia , and right hemiparesis with a nihss score of 19 .
non - enhanced brain ct revealed no hemorrhagic density , and cta showed an occlusion of the m1 segment of the left mca ( fig .
a 9-fr balloon guide catheter ( optimo ; tokai medical , aichi , japan ) was advanced from the right femoral artery to the left cervical ica .
steam shaping of the tip of the dac ( catalyst 6 ; stryker , kalamazoo , mi , usa ) was performed to facilitate passage through the ophthalmic segment . under roadmap guidance , the dac with a .021-inch microcatheter and a .014-inch microguidewire ( traxcess 14 ex ; microvention , tustin , ca , usa ) was advanced to the proximal m1 segment of the left mca ( fig .
the dac was wedged to the thrombus with direct manual aspiration using a 50-ml syringe .
the bgc was inflated after confirming arrest of blood aspiration into the syringe , and the dac was gently retrieved maintaining manual aspiration . during retrieval of the dac , blood was aspirated into the syringe and the aspirate contained a large thrombus .
a 71-year - old female patient with no medical history of hypertension , diabetes mellitus , or arrhythmia was admitted to our hospital .
the initial neurologic examination revealed a stuporous mental status and quadriparesis with a nihss score of 28 . on admission ,
her blood pressure was 134/69 mmhg , her blood glucose level was 110 mg / dl , and electrocardiography revealed sinus tachycardia .
non - enhanced brain ct was unremarkable , and cta showed an occlusion of the distal basilar artery ( fig .
a 6-fr guide catheter ( envoy ; cordis , miami , fl , usa ) was positioned from the right femoral artery to the distal v2 segment of the left vertebral artery . under roadmap guidance ,
the 5-fr dac ( sofia ; microvention , tustin , ca , usa ) with a .021-inch microcatheter and a .014-inch microguidewire was advanced to the proximal end of the occluded basilar artery ( fig .
then , direct manual aspiration using a 50-ml syringe through the dac was conducted and a large thrombus was aspirated into the syringe .
a 47-year - old female patient was admitted to our hospital with left limb weakness . she had no prior medical history of hypertension , diabetes , or atrial f ibrillation .
the initial neurologic examination demonstrated a drowsy state , left hemiparesis , and dysarthria with a nihss score of 8 .
her vital signs were stable with a blood pressure of 170/90 mmhg and a serum glucose level of 71 mg / dl .
non - enhanced brain ct revealed no hemorrhagic density and cta showed an occlusion in the distal basilar artery ( fig .
endovascular mechanical thrombectomy was performed under conscious sedation . a 6-fr guide catheter ( chaperon , microvention , tustin
, ca , usa ) was introduced from the right femoral artery to the distal v2 segment in the left vertebral artery .
a dac ( navien 058 ; ev3/covidien , irvine , ca , usa ) coaxilally with a .021-inch microcatheter ( prowler select plus ; cordis , miami , fl , usa ) and a .014-inch microguidewire ( synchro-14 ; stryker , kalamazoo ,
mi , usa ) was advanced to the proximal end of the occluded segment ( fig .
after retraction of the microcatheter and microguidewire , direct aspiration with the dac was performed using a 50-ml syringe .
the retrieved catheter showed a large thrombus wedged within it , and complete reperfusion was achieved ( fig .
a 71-year - old male patient with a medical history of hypertension and hyperlipidemia was admitted to our hospital with right limb weakness . on arrival ,
his blood pressure was 115/65 mmhg , his blood sugar level was 113 mg / dl , and electrocardiography showed a sinus rhythm .
initial neurologic examination revealed right facial palsy , global aphasia , and right hemiparesis with a nihss score of 19 .
non - enhanced brain ct revealed no hemorrhagic density , and cta showed an occlusion of the m1 segment of the left mca ( fig .
a 9-fr balloon guide catheter ( optimo ; tokai medical , aichi , japan ) was advanced from the right femoral artery to the left cervical ica .
steam shaping of the tip of the dac ( catalyst 6 ; stryker , kalamazoo , mi , usa ) was performed to facilitate passage through the ophthalmic segment . under roadmap guidance , the dac with a .021-inch microcatheter and a .014-inch microguidewire ( traxcess 14 ex ; microvention , tustin , ca , usa ) was advanced to the proximal m1 segment of the left mca ( fig .
the dac was wedged to the thrombus with direct manual aspiration using a 50-ml syringe .
the bgc was inflated after confirming arrest of blood aspiration into the syringe , and the dac was gently retrieved maintaining manual aspiration . during retrieval of the dac , blood was aspirated into the syringe and the aspirate contained a large thrombus .
a 71-year - old female patient with no medical history of hypertension , diabetes mellitus , or arrhythmia was admitted to our hospital . the initial neurologic examination revealed a stuporous mental status and quadriparesis with a nihss score of 28 . on admission ,
her blood pressure was 134/69 mmhg , her blood glucose level was 110 mg / dl , and electrocardiography revealed sinus tachycardia . non - enhanced brain ct was unremarkable , and cta showed an occlusion of the distal basilar artery ( fig .
a 6-fr guide catheter ( envoy ; cordis , miami , fl , usa ) was positioned from the right femoral artery to the distal v2 segment of the left vertebral artery . under roadmap guidance ,
the 5-fr dac ( sofia ; microvention , tustin , ca , usa ) with a .021-inch microcatheter and a .014-inch microguidewire was advanced to the proximal end of the occluded basilar artery ( fig .
then , direct manual aspiration using a 50-ml syringe through the dac was conducted and a large thrombus was aspirated into the syringe .
theoretically , aspiration thrombectomy may be generally safe due to the rarity of vessel wall irritation or damage , and the use of a large diameter dac might improve the wedging and extracting of a thrombus , which may in turn lead to better reperfusion results . in this case series , we presented fast using various dacs in patients with ais .
successful reperfusion was achieved in all cases . there were no complications related to the endovascular procedure . with the continuing evolution of mechanical thrombectomy devices ,
aspiration thrombectomy strategies have advanced from the traditional penumbra aspiration system to forced arterial suction thrombectomy ( fast ) and a direct aspiration first - pass technique ( adapt ) .
generally , mechanical thrombectomy in patients with ais is a time sensitive procedure , and successful recanalization within a short procedure time is important for increasing the likelihood of a good outcome .
direct aspiration strategies such as fast and adapt may be advantageous with respect to fast , repetitive attempts during a procedure , because aspiration thrombectomy does not need stent re - sheathing and re - selection for an occluded artery .
based on previous reports of mechanical thrombectomy using a penumbra reperfusion catheter , new generation devices ( 5max ace , 5max ; penumbra , alameda , ca , usa ) having a larger diameter have demonstrated a faster ( 36.6 vs 41.2 min ) and higher rate of tici 2b/3 reperfusion ( 81.8% vs 95% ) in comparison to old generation devices ( 041 , 032 ) .
our aspiration thrombectomy strategy using dacs was also based on the idea that the aspiration force is proportional to the cross - sectional area of the catheter , and forceful aspiration with a large - diameter catheter is advantageous with respect to wedging and extracting the thrombus .
we therefore attempted aspiration thrombectomy with 3 different kinds of large bore dacs , all of which had a larger inner diameter in comparison to the penumbra 5max reperfusion catheter .
successful reperfusion was achieved with each kind of dac . despite the advantage of aspiration thrombectomy using a large bore catheter
first , there might have been a difficulty in delivering the aspiration catheter to the target occlusion .
passage through the ophthalmic segment of the ica might present a challenge with respect to accessing to the target .
manufacturers designed the distal part of the dac to be soft and flexible to improve trackability .
we used a coaxial technique with a .021-inch microcatheter and steam - shaped the distal tip of the dac . in case 2 ,
a second , larger guide catheter had to be introduced for the use of a large bore catheter . in cases of posterior circulation occlusion ,
selection of a guide catheter might be considered for a diameter of the vertebral artery .
aspiration thrombectomy with a penumbra reperfusion catheter ( 5max , 4max ) can not be introduced into a conventional guide catheter , such as 6 or 7-fr envoy or chaperon , because of the larger outer diameter ( .080 inch ) . despite an inner diameter larger than the penumbra reperfusion catheter ,
the outer diameter of the dacs used in our cases was less than or equal to .070 inches , and could be applied . in conclusion , fast using a large bore distal access catheter may be a viable treatment option for ais .
however , we can not guarantee the safety and efficacy of this strategy due to our limited number of cases .
but regarding technical aspects , fast with a dac is simple , fast , and straightforward .
historical innovations in mechanical thrombectomy devices and strategies for ischemic stroke have resulted in improved angiographic outcomes and better clinical outcomes . 
 various devices have been used , but the two most common approaches are aspiration thrombectomy and stent - retrieval thrombectomy . 
 aspiration thrombectomy has advanced from the traditional penumbra system to forced arterial suction thrombectomy and a direct aspiration first - pass technique . 
 newer generation aspiration catheters with flexible distal tips and a larger bore have demonstrated faster and better recanalization relative to older devices . 
 recently , several species of distal access catheters have similar structural characteristics to the penumbra reperfusion catheter . 
 therefore , we used the distal access catheter for forced arterial suction thrombectomy in three patients with acute ischemic stroke . in each case 
 , we achieved fast and complete recanalization without significant complications . 
 forced arterial suction thrombectomy using a distal access catheter might provide another option for mechanical thrombectomy in patients with acute ischemic stroke .