Prevention of arterial graft spasm by botulinum toxin: an in-vitro experiment

In coronary artery bypass surgery, arterial grafts result in improved patency rates. However, these grafts frequently fail due to spasm. Papaverine has been used to prevent graft spasm, but its effect is short-lived. Botulinum toxin inhibits muscle contraction for about three months. We investigated the usefulness of botulinum toxin in preventing arterial grafts spasm in vitro. Samples of abdominal aorta from male Wistar rats were cut into 2 mm rings and treated with various doses of botulinum toxin or papaverine for 30 min. All rings were stimulated with KCl and noradrenaline. Tension was recorded using myography. We compared constriction caused by noradrenaline or KCl in rings treated with botulinum toxin, or papaverine, or physiological salt solution (PSS) (control). In the presence of KCl and noradrenaline, almost all concentrations of botulinum toxin completely inhibited arterial contraction when compared with controls. Spasm prevention was lost after 60 min in rings with papaverine but persisted for 120 min in rings with botulinum toxin. In the histological examination, arterial wall structure was not destroyed by botulinum toxin. Botulinum toxin prevented arterial graft spasm in vitro and had a longer lasting effect than papaverine, with no toxic effect on the artery.