This site's own FAQ and footer both state this directly: Butcher's Broom may affect blood pressure.
Butcher's Broom is the traditional circulation botanical in this formula, independently associated with an effect on blood pressure — worth taking this caution seriously if you take blood-pressure medication.
Talk to your doctor before starting if you take blood-pressure medication or have a diagnosed cardiovascular condition, and monitor how you feel closely in the first weeks of use.