Effect of normothermic papaverine to relieve intraoperative spasm of the internal thoracic artery.

BACKGROUND

After mobilization, vasospasm often reduces flow through the internal thoracic artery. An established method of relaxing the artery and increasing flow is to use papaverine at ambient temperature (20 degrees to 22 degrees C) as a topical vasodilator. However, the pharmacologic actions of papaverine generally have been assessed at 37 degrees C.

METHODS

In 60 patients in whom the left internal thoracic artery was used for myocardial revascularization, we investigated the effects of normal saline solution at 20 degrees C (group I), papaverine at 20 degrees C (group II), and papaverine at 37 degrees C (group III). Under controlled hemodynamic conditions, free flow was measured before any pharmacologic intervention and a median of 16 minutes after the pedicle had been sprayed with one of the agents.

RESULTS

Normal saline solution at 20 degrees C produced a small increase in flow from 37.5 +/- 8.1 mL/min to 50 +/- 10.2 mL/min. A significant increase occurred with papaverine at 20 degrees C, from 38.05 +/- 6.5 mL/min to 78.75 +/- 21.2 mL/min (p < 0.0001). Papaverine at 37 degrees C, however, produced an increase in flow from 36.9 +/- 12.6 mL/min to 103.3 +/- 44.6 mL/min (p < 0.0001) and proved to be more effective than papaverine at room temperature (p = 0.0174).

CONCLUSIONS

We recommend topical use of papaverine at 37 degrees C to relieve intraoperative spasm of the internal thoracic artery.