EFFECT OF NORMOTHERMIC PAPAVERINE TO RELIEVE INTRAOPERATIVE SPASM OF THE INTERNAL THORACIC ARTERY

Background. After mobilization, vasospasm often reduces flow through t he internal thoracic artery. An established method of relaxing the art ery and increasing flow is to use papaverine at ambient temperature (2 0 degrees to 22 degrees C) as a topical vasodilator. However, the phar macologic actions of papaverine generally have been assessed at 37 deg rees C. Methods. In 60 patients in whom the left internal thoracic art ery was used for myocardial revascularization, we investigated the eff ects of normal saline solution at 20 degrees C (group I), papaverine a t 20 degrees C (group II), and papaverine at 37 degrees C (group III). Under controlled hemodynamic conditions, free flow was measured befor e any pharmacologic intervention and a median of 16 minutes after the pedicle had been sprayed with one of the agents. Results. Normal salin e 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, prod uced an increase in now 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 r oom temperature (p = 0.0174). Conclusions. We recommend topical use of papaverine at 37 degrees C to relieve intraoperative spasm of the int ernal thoracic artery.