Pharmacological assessment of composite arterial conduits using angiography early in the postoperative period.
OBJECTIVE
Muscular arteries are vulnerable to vasospasm unlike elastic arteries. Having developed experimental models of composite arterial grafts, we assessed and compared the responses of the grafts with different pharmacological agents using angiography early in the postoperative period.


METHODS
We harvested the internal thoracic artery (ITA) and brachial-median artery (BMA) from 10 sheep. BMA was used as an alternative to the radial artery. Each vessel was assessed histologically and morphologically. Then, a serial composite graft was constructed so that BMA was interposed. On postoperative day one or two, angiography was performed on the composite graft to measure the diameter of each vessel in response to phenylephrine (alpha-adrenergic receptor agonist), nitroglycerin+phenylephrine, and milrinone+phenylephrine.


RESULTS
The BMA had a wide media layer which consisted of abundant smooth muscle cells. The combined intima and media were thicker in BMA than in ITA (p<0.01). After injection of phenylephrine, the BMA diameter decreased (2.5+/-0.4 mm to 1.9+/-0.3 mm, p<0.01), while the ITA diameter remained unchanged (3.7+/-0.2 mm to 3.6+/-0.2 mm). Continuous infusion of nitroglycerin or milrinone prevented phenylephrine-induced vasoconstriction of the BMA (p<0.05).


CONCLUSIONS
These results suggest that muscular arteries have a more pronounced vasoconstrictive response to alpha-adrenergic receptor agonists than the elastic arteries. To avoid potential decrease in graft flow of muscular artery, it is advisable to use a vasodilator nitroglycerin or milrinone early in the postoperative period.
Ueyama
Koji
K
Department of Cardiovascular Surgery, the Graduate School of Medicine, Kyoto University, Kyoto, Japan.
Nishimura
Kazunobu
K
Ikai
Akio
A
Koyama
Tadaaki
T
Nishina
Takeshi
T
Ikeda
Tadashi
T
Komeda
Masashi
M
D000818:Animals; D001916:Brachial Artery / Q000000981:diagnostic imaging / Q000187:drug effects* / Q000637:transplantation; D003329:Coronary Vasospasm / Q000139:chemically induced / Q000188:drug therapy; D008323:Mammary Arteries / Q000000981:diagnostic imaging / Q000187:drug effects* / Q000637:transplantation; D020105:Milrinone / Q000494:pharmacology*; D005996:Nitroglycerin / Q000494:pharmacology*; D010656:Phenylephrine; D011184:Postoperative Period; D011859:Radiography; D012756:Sheep; D017539:Tunica Intima / Q000187:drug effects / Q000473:pathology; D017540:Tunica Media / Q000187:drug effects / Q000473:pathology; D014662:Vasoconstrictor Agents; D014665:Vasodilator Agents / Q000494:pharmacology*
D014662:Vasoconstrictor Agents; D014665:Vasodilator Agents; D010656:Phenylephrine; D005996:Nitroglycerin; D020105:Milrinone