Internal thoracic artery response to papaverine: takes time

Takeuchi and associates found that exposure of the internal thoracic artery to intralumenal papaverine for 1min did not increase free flow [1]. It is well known that maximal vasodilation to papaverine requires at least 10min of exposure [2] so that their comparison is unfair and should be appropriately qualified.

It is also germane that papaverine inhibits cyclic nucleotide phosphodiesterase although it is not established that this is the mechanism for vasodilation [3].

It has been my practice for 30 years to treat all arterial conduits with intraluminal papaverine in heparanized blood (2mg/ml) to achieve a maximally dilated conduit at the time of graft placement. Diluting the papaverine in blood results in a pH of 7.3 because of the buffering capacity of blood [4].

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