it consists of these phases : filling , congestion , rigidity and full erection ( 1 ) . noteworthy to know is that in most of the patients , maximum psv happens in the first 5 minutes ; moreover , in a minority of patients all the process of changes happen in the first 5 minutes ( 5 ) . for better description of these dynamic changes , we got an idea from the study of fitzgerald al . ( 5 ) and tried to designate dynamic patterns for spectral waveform changes of cavernosal arteries in each patient . in this study , we tried to classify our patients based upon their patterns of changes in a dynamic study and to subsequently better describe their underlying problem . this case series study was conducted in hasheminejad urology center , iran university of medical sciences ( iums ) , from april 2011 till april 2012 . we evaluated 59 men who were referred from a urology clinic for post - ici color doppler investigation of suspected ed . the stages of the test and possible role of the study in their therapeutic plan were described comprehensively for each patient and then a written consent was obtained . the demographic data and medical history including duration of ed , history of diabetes , hypertension , cigarette smoking , drug history and previous interventions for vascular diseases were recorded . one of this study investigators ( gharib , mh . ) performed all examinations with a linear ( 5 - 10 mhz ) probe of esaote technos device ( italy , 2002 ) . the probe was placed over the ventral aspect of the penis and scans were performed in longitudinal and transverse planes before injection of the vasoactive agent . we used papaverine hydrochloride because of the availability and acceptable price . for post - ici assessment , first a maximum dose of 40 mg papaverine was injected into the right corpus covernosum , at the junction between the middle and distal third of the penile dorsal aspect . if maximum psv did not reach 30 cm / s in 5 minutes , further injections of 20 mg doses of papaverine were also performed , up to a maximum total dose of 80 mg . scanning started about one minute after the injection and each of the cavernosal arteries was evaluated continuously thereafter until either erection happened or psv started to decline . parameters such as psv , edv , minimum of resistive index ( ri ) and time to reach maximum psv were recorded . if full erection happened , the patient was under observation and if erection persisted for more 3 hours , the patient was sent to the urologic emergency room for appropriate interventions . based on temporal changes in the waveform of cavernosal arteries , new patterns were defined . patients were classified based on previously known etiologic categories ( i.e. arterial insufficiency , venous leak , mixed type , and normal response ) and also categorized into these new patterns . fifty - nine patients with the mean age of 45.6  13.1 ( 24 to 74 ) years were enrolled into this study . twenty - two cases revealed normal response ( non - organic causes as 37.3% ) , 27 were classified as venous leakage , eight with arterial insufficiency and two were considered as mixed type . the mean time to reach maximum psv was 3.4  0.8 minutes ( median 3 , range 2 - 5 minutes ) in 51 patients without arterial insufficiency . we defined 8 patterns for the temporal changes in cavernosal arterial waveform in our patients ( table 1 ) . for classification , we considered four different aspects in our study : sufficiency of cavernosal arteries [ for judgement of this sufficiency , we considered points such as maximum psv during the study ( cut point of 30 cm / s ) , amount of difference of psv between the two sides ( below or above 10 cm / s ) , acceleration time of each waveform ( cut point of 80 ms ) and pattern of blood filling in the arteries ] competent filling of sinusoidal blood pools [ including qualitative assessment of edv ( considered as satisfactory or not ) and duration of edv rise ( at least one minute ) ] veno - occlusive capability of corpus cavernosum [ even though a clinically assessed full erection is the best determinant . in doppler study , long time persistence of vigorous diastolic flow ( edv more than 5 cm / s ) would be the indicator ] . finally , how long did it take the study to be finished ( below or above 5 minutes ) . we defined a psv level more than 40 cm / sec as a requisite to consider the patient as having venous leak with no arterial component based on benson et al . those patients with a psv between 30 and 40 who did not elicit erection were placed in category 2 under the label of mixed type . patterns 3 , 4 and 5 denote to previously known venous leak group and patterns 6 , 7 and 8 are patients with normal response . table 2 shows the patient classification based on various patterns of arterial spectral waveform changes . among all , 8 patients completed all phases of erection in the first 5 minutes ( one with pattern 3 and 7 with pattern 6 ) . pattern 5 was considered as the common pattern of venous leak ; while patterns 3 and 4 were considered as the uncommon group . in our study , six patients demonstrated the uncommon patterns of venous leak ( 22.2% of all patients with venous leak ) . the mean of psv was not different between these two groups ( 57.7 vs. 52.5 cm / s , p = 0.38 ) . mean age and minimum recorded ri were higher in the uncommon group , although they did not show statistical significance ( p = 0.14 and 0.22 , respectively ) . hypertension was more prevalent in the uncommon pattern of venous leak ( p = 0.01 ) . smoking was more prevalent in patients with uncommon patterns ; however , the difference was not statistically significant ( p = 0.29 ) . we detected one patient with micropenis who demonstrated normal pattern of changes in response to papaverine even though with a maximum psv under 30 cm / s . htn , hypertension ; psv , peak systolic velocity ; ri , resistive index . in this study , we investigated continuous assessment of cavernosal arterial waveforms of patients with ed in comparison with its routine doppler evaluation . the conventional method of post ici of papaverine color doppler study includes recording psv and edv values in the cavernosal artery spectral waveform 5 minutes after injection which is repeated every 5 minutes afterward up to 30 minutes ( 1 , 4 ) . we found that in most patients ( 92.2% ) , maximum psv happened before the fifth minute . fitzgerald et al . also showed this finding in a considerable percent of their patients ( 76% ) ( 5 ) . this emphasizes the need for early initial assessment of flow in cavernosal artery after the injection of papaverine . they are filling , tumescence , rigidity and full erection ( 1 , 3 , 4 , 8) . it is obvious that these events will result in a sequence of changes in the waveform of cavernosal artery . a process that can be chased meticulously in a continuous color doppler protocol ( figure 1 ) . conventionally four groups of responses have been defined : arterial insufficiency , venous leak , normal response and a mixed pattern ( 9 ) . for better delineation of dynamic changes during ultrasonography , we got the idea of categorizing waveform pattern changes during continuous assessment from the study conducted by fitzgerald et al . ( 5 ) and defined 8 patterns of changes for arterial spectral waveform . in our classification , we considered subgroups for patients with the uncommon pattern of venous leak and those with normal response based on the response within the first 5 minutes after injection or thereafter ( patterns 3 and 4 ; and patterns 6 and 7 respectively ) . the left column of the image shows tumescent phase in this patient 2 minutes after injection . in the middle column , finally , the right column depicts waveforms in the rigidity phase in the 6th minute . we noticed that all phases of the response to papaverine occurred within the first 5 minutes in 13.8% of our patients ( 1 with pattern 3 and 7 with pattern 6 ) . in conventional practice , for patients with pattern 3 , we might need to repeat the injection or just judge based on the clinical fact that erection has not happened . systolic velocity starts to decline and the arterial system , especially helicine arterioles become progressively less visible ( 4 ) . so here , we were not able to designate a normal response based on the findings of the study and just the occurrence of full erection would be the clue for our normal reports . these findings again clarify the importance of careful observation of changes both continuously and from the early beginning . we used to designate 4 groups to our patients based upon findings in the conventional study . in fact in the conventional study , the sufficiency of the arterial system and veno - occlusive mechanisms of corpus cavernosum are the mainstay of classification ; however , we think that one more aspect should be delicately followed in the process of erection , and that is the appropriate reaction of sinusoidal blood pools in each cc . an important outcome of this dynamic study is distinction between patients formerly designated as having  venous leak  . normally , a marked increase in psv should result in concomitant significant rise in the diastolic blood flow . we believe that patterns 3 and 4 are related to a more decreased amount of trabecular smooth muscles and/or a change in the fibroelastic composition of cc , what we considered as the competency of filling of sinusoidal blood pools or in other words , effective congestion . consequently , in color doppler study , the diastolic flow will not rise to a favorable amount for an acceptable duration ( figure 2 ) . these patients , although few ( 6 patients in this study ) , seem to have more aggravated problems and would not have a satisfactory response to common medications used for venous leak and should be directed for prosthesis placement . the meanage and the lowest recorded ri are higher in this group of venous leak , which we labeled arbitrarily as the uncommon group , compared to the common group ( 54.5 vs. 46.3 and 77.7 vs. 74.3 , respectively ) . although possibly due to the small number of patients , they did not show statistical significance ( p value 0.14 and 0.22 , respectively ) . the probable extensive changes in tissue texture of patients with uncommon venous leak would result in a lesser degree of diastolic flow compared to the common pattern . as the patient grows older , the ratio of collagen type 3 ( the elastic one ) counts down and collagen type 1 gradually replaces it . moreover , the content of trabecular smooth muscle also decreases up to 35% ( 1 ) . hypertension and smoking have been introduced as other important factors involved in the extent of changes in the tissue texture of cc ( 1 ) . however , in our study the prevalence of smoking was still not statistically significant in the uncommon venous leak group ( p = 0.29 ) . we think that the amount and duration of smoking ( quantified in pack - year ) may alter the pattern of response in patients with venous leak . as the pack - year of smoking inflates , we had one patient that showed erection with psv values below 30 cm / sec . the amount of blood flow directed to cc depends on the volume of recipient sinusoidal blood pools . it is obvious that in a patient with micropenis , a lesser amount of flow is needed to result in erection and the maximum psv ( one important determinant of flow ) would be lower compared to other normal responders with a normal - sized penis , even below the required post injection psv of more than 30 cm / s . while , in a continuous study , we can follow the normal sequence of changes in cc and easily denote that the patient has no vascular problem . in conclusion , we highlight a considerable role of early and continuous evaluation started one minute after ici for better description of underlying pathologies of ed especially in patients with venous leak etiology . this study was just a  case series  to obtain a general concept about the benefits of a dynamic study . the patterns described here are just those seen in these 59 cases . in further studies with a larger sample size , it may be possible to declare new patterns or more sharply elucidate the characteristics of the aforementioned groups . the two left columns are waveforms of a patient with the common pattern of venous leak ( pattern 5 ) in the 3rd and 8th minutes , respectively . the two right columns are for a patient with an uncommon pattern of venous leak ( pattern 4 ) in approximately similar times . note the prominent diastolic flow ( edv = 19cm / s ) in the left side patient , while the diastolic flow in the right side patient is not as much vigorous ( edv = 8 cm / s ) throughout the dynamic study .