This is the first phase and occurs immediately after a break in a vessel wall, with three steps identified in the haemostasis phase: vascular spasm
, formation of a platelet plug and coagulation, with platelets being the main components of this phase.
Atherosclerosis has been shown to impair endothelial vasodilation in experimental animal models (38) and in humans (39), and may lead to vasoconstriction and vascular spasm
. Many studies have shown that the vascular relaxation response is caused by the relaxation factor (EDRF) originating from the endothelium (40).
They include several subclinical and clinically significant causes of vascular brain injuries including intracranial atherosclerosis, aneurysms, vasculitis, vascular spasm
, vascular malformations, chronic cerebral hypoperfusion, infarction, and haemorrhages.
Another cause is peripheral vascular spasm
due to exaggerated responses in sympathetic nerves and fluid factors, such as vasopressin and angiotensin, accompanying decreases in cardiac output and circulating plasma volume .
Also, vasoconstriction by an anesthetic agent depleting blood flow or triggering a stress-induced vascular spasm
has been reported [7, 8].
In this particular case, the LIMA was harvested in skeletonized fashion, questioning whether minimal thermic injury could effectively contribute to protecting the arterial graft against vascular spasm
In surgery, the presence of an abnormal arc around the superior pubic ramus is lower than in anatomical dissections (Darmanis et al.), possibly due to vascular spasm
product traumatic laceration, which makes it difficult to identify (Okcu et al.).
This may confirm the hypothesis that the disturbances of retrobulbar circulation may appear as a response to systemic pressure alteration, conceivably occurring as a vascular spasm
or vasoconstrictive hypersensitivity [33,39].
 Other proposed theories include end artery damage, sympathetic stimulation followed by vascular spasm
which in turn leads to necrosis.
They may result in severe vascular spasm
, endothelial damage, and increased vascular permeability, which cause vascular occlusion and limb gangrene.
In two patients embolization was not successful and the reason of failure was difficult catheterization of the supplying artery, due to complex anatomy and vascular spasm
. Both patients were subsequently managed by surgery.
No case of vascular complications such as major access site bleeding, vascular perforation, brachial artery occlusion causing forearm ischemia, compartment syndrome, vascular spasm
or failure to catheterize coronary arteries requiring alternate vascular access were observed.