Background: Current ex-vivo analyses of arterial bypass conduits` are limited to wire myographs. Inherent disadvantages that may bias characterization of the pharmacodynamics include (1) deviation of segment geometry and loading from physiological conditions, (2) injury induction during preparation of vessel-ring, and (3) outer and luminal surfaces are subjected to vasoreactive agents. Whereas recent interest has focused on use arterial conduits during coronary artery bypass grafting (CABG), their vasoreactive properties, general and segmental, remain to date undetermined. A novel computerized myograph was designed to overcome the shortcuts of the wire-ring model.
Methods: Left and right internal thoracic artery (ITA; LITA, RITA) and radial artery (RA) segments were extracted during CABG following harvesting and prior to grafting. The arterial segment was immersed in an organ bath and exposed to luminal transfusion of physiological solution with or without vasoconstrictor agents. The segment was controlled for axial stretch and internal pressure. Deviations in vessel diameter in terms of contraction or dilatation were monitored by designated highly accurate photographic device and analyzed by a computerized system (Figure 1).
Results: Experiments were performed on 15 ITA and RA segments exposed to norepinephrine. ITA and RA segments immersed in topical papaverine solution (20 minutes or longer) were insensitive to the norepinephrine.
Conclusions: Technical aspects of this novel model will be presented. Experimental protocols aimed at investigating the validity of past results obtained by the wire-ring myographs will be discussed. Whether the effects of papaverine solution are transitory or permanent remain to be examined. Additional preliminary results of ITA and RA response to vasoreactive agents will be presented.
