title: Different hemodynamic responses by color Doppler ultrasonography studies between sildenafil non-responders and responders.
abstract: OBJECTIVE
  To determine if there are different penile hemodynamic patterns between sildenafil non-responders and responders by using color Doppler ultrasonography.
  
  
  METHODS
  A total of 69 erectile dysfunction (ED) patients aged 22-79 years were enrolled into the present study. Thirty-eight (55.1%) men with ED who did not respond to four attempts of treatment with 100 mg sildenafil after re-education were classified as sildenafil non-responders. A combination of three vasodilator drugs, 1.25 mg papaverine, 0.4 mg phentolamine and 5 mg prostaglandin E1, was given by intracavernous injection before penile Doppler ultrasonography was carried out. The erectile response to intracavernous injection and vascular parameters including peak systolic velocity (PSV), resistance index (RI), end diastolic velocity (EDV) and cavernosa artery diameter (CD) were measured and the results between sildenafil non-responders and responders were compared.
  
  
  RESULTS
  No statistical difference in vascular parameters measured by Doppler ultrasonography studies between non-responders and responders was noted. Sildenafil non-responders had a poorer penile rigidity response to intracavernous injection than responders (P < 0.05). Among patients with adequate PSV (>or=30 cm/s) and abnormal EDV (> 5 cm/s), individuals in the non-responder group had fewer positive responses to intracavernous vasodilator injection than in the responder group (35.3% vs. 72.2%, P < 0.05). Advanced age and comorbidity with diabetes mellitus were significantly associated with sildenafil non-response (P < 0.05).
  
  
  CONCLUSIONS
  Sildenafil non-responders were characterized by a poorer penile rigidity response to intracavernous injection and had an associated impaired veno-occlusive mechanism. Advanced age and comorbidity with diabetes mellitus were two common factors associated with non-response.
authors.affiliation: Section of Andrology and Female Urology, Division of Urology, Department of Surgery, Chang Gung Memorial Hospital-Linkou, Chang Gung University, College of Medicine, Taoyuan 333, Taiwan, China. strong00@ms9.hinet.net
authors.forename: Shih-Tsung
authors.initials: ST
authors.lastname: Huang
authors.forename: Ming-Li
authors.initials: ML
authors.lastname: Hsieh
mesh_terms: D000328:Adult; D000368:Aged; D000527:Alprostadil / Q000627:therapeutic use; D007172:Erectile Dysfunction / Q000000981:diagnostic imaging* / Q000188:drug therapy*; D006801:Humans; D008297:Male; D008875:Middle Aged; D010208:Papaverine / Q000627:therapeutic use; D010646:Phentolamine / Q000627:therapeutic use; D010879:Piperazines / Q000627:therapeutic use*; D011687:Purines / Q000627:therapeutic use; D000068677:Sildenafil Citrate; D013450:Sulfones / Q000627:therapeutic use*; D018615:Ultrasonography, Doppler, Color; D014665:Vasodilator Agents / Q000627:therapeutic use*
chemical_list: D010879:Piperazines; D011687:Purines; D013450:Sulfones; D014665:Vasodilator Agents; D000068677:Sildenafil Citrate; D010208:Papaverine; D000527:Alprostadil; D010646:Phentolamine