The relationship of penile rigidity and intracavernous vascular resistancein potent men during intracavernous pharmacological testing

Purpose: We studied the relationship of penile rigidity and intracavernous vascular resistance in potent men during intracavernous pharmacological tes ting. Materials and Methods: Enrolled in our study were 19 potent men undergoing intracavernous pharmacological testing for various reasons. Hemodynamic cha nges in response to the intracavernous injection of 20 mug. prostaglandin E 1 were assessed by color Doppler sonography with simultaneous RigiScan (Dac omed Corp., Minneapolis, Minnesota) monitoring of penile rigidity. The rela tionship of penile rigidity and intracavernous vascular resistance was dete rmined by correlating hemodynamic data with recorded penile rigidity values . Results: Maximal mean rigidity plus or minus standard deviation of the peni le tip and base after intracavernous injection of prostaglandin E1 was 76.8 % +/- 8.5% and 97.3% +/- 4.7%, respectively. Penile tip and base rigidity c orrelated positively with the resistive index (r = 0.69 and 0.75, p <0.0001 ) and negatively with end diastolic velocity (r = -0.62 and -0.70, respecti vely, p <0.0001). The formula, rigidity = -128 + 195 X resistive index, was derived to describe the linear regression of penile base rigidity and the resistive index. The formula, rigidity = 59.8 3.3 X end diastolic velocity, was derived to describe the linear regression of penile base rigidity and end diastolic velocity. Conclusions: Penile rigidity correlated strongly with intracavernous vascul ar resistance in potent men during intracavernous pharmacological testing. The resistive index and end diastolic velocity of the cavernous arteries ma y each be used to estimate penile rigidity quantitatively.