Twenty-eight out of 79 interventionists from 17 comprehensive Dutch stroke centers (35%) completed the survey.
Experience of the responders
Thirteen interventionists had 1–5-years experience in neuro-intervention. Eleven had 5–10-years experience and 4 had more than 10 years experience in the field of neuro-intervention.
Heparin concentration
Twenty-one participants responded to which concentration of heparin they used in the flush fluids. For the non-responders, we used heparin concentrations derived from colleague responders from the same center (if available) or from known heparin concentration from an earlier conducted center-based survey (Benali et al., 2021). Two out of 28 interventionists use 25.000 IU/L saline flush, 6 use 10.000 IU/L, 10 use 5.000 IU/L, 2 interventionists use 1000 IU/L, and 8 interventionists use no heparin in flush fluids during EVT.
Number of infusion lines
Five interventionists completed the survey with two different options; for calculations of total heparin dose, we only included the maximal number. Sixteen participants use 3 infusion bags during the procedure (one on the (balloon) guiding catheter and / or one on the aspiration catheter and / or one on the microcatheter), 5 interventionists use 2 bags (on the (balloon) guiding catheter, aspiration catheter or microcatheter) and 7 use only 1 bag (on the (balloon) guiding catheter).
Timing of connection of the infusion bag
Twenty-six interventionists connected the infusion bag immediately at the start of the procedure. Two interventionists connected the infusion bag after catheterization of the common carotid artery. We did not include the time-delay from groin puncture to carotid artery catheterization (time of using catheter without flush) in our final calculations of total dose, because of the small number and potentially short time delay.
Drip rate
All the participating interventionists set up their dripping speed manually. The most often set drip rate was 1 drip per second (0,05 ml/sec) (n = 18), followed by 0,5 drip per second (0,025 ml/sec) (n = 10); 2 drips per second (0,1 ml/sec) (n = 2) and 1 drip per 5 s (0,01 ml /sec) (n = 1).
Calculated heparin dose per hour
Twenty-five respondents use the same drip rate for every catheter, three used 2 different drip rates during the same procedure. Two out of three did not use heparin in their infusion bag. As for the other one, a microcatheter rate of 0,5 drip/sec and a guiding catheter rate of 1 drip/sec gives was used, given a total drip rate of 1.5 drip/sec for the 2 infusion bags. See Fig. 1 for the different doses of heparin IV per hour. The median dose is 1350 IU/h (IQR of 2700 IU/h) with a minimum of 0 IU/h and a maximum of 13,500 IU/h.