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.
Four stages are defined for a process of penile erection. 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).
Figure 1. Sequence of changes was tracked in a continuous color doppler study in a normal responder (pattern 7)
Rows are right and left cavernosal arteries, respectively. The left column of the image shows tumescent phase in this patient 2 minutes after injection. In the middle column, transition to rigidity phase is happening at the 4th minute. Finally, the right column depicts waveforms in the rigidity phase in the 6th minute. Subsequently, erection happened in this patient.
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. The scenario is the same for cases with pattern 6. With maximum rigidity, 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). We used minimum recorded RI as a measure for diastolic flow in patients. 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). The above mentioned changes would result in non-compliant sinusoids. We showed that the prevalence of systemic hypertension was statistically higher in this group. 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, the extent of tissue component alterations would increase. We had one patient that showed erection with PSV values below 30 cm/sec. He was a case of micropenis. 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.
Figure 2. Continuous doppler waveform study of the cavernosal artery in patients with common and uncommon patterns of venous leak
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. Rows are right and left cavernosal arteries. 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. The flow decreased in both patients and the waveform finally reverted to flaccid state. Clinically, erection did not happen.