Penile vascular surgery for treating erectile dysfunction: Current role and future direction

A detailed analysis of the penile fibro-vascular assembly

BACKGROUND

Although various compartments of the human cardiovascular system have been thoroughly elucidated, the penile fibrovascular assembly remains an exception that has yet to be fully explored; therefore, this gap in our understanding prompts us to conduct further investigations.

AIM

This study revisits the penile-fibro-vascular assembly to determine whether it constitutes an independent vascular compartment within the human body.

METHODS

The penile-fibro-vascular assembly was meticulously examined in 23 male human cadavers. The loupe-assisted observation was used to compare the size of bilateral penile arteries, conspicuously addressed at the hilum, and to isolate erection-related vascular channels meticulously with a loupe, as extensively as possible. Additionally, a comprehensive library was analyzed, including 801 cadaveric images, 1001 sets of dual cavernosographies, 11 spongiosographies, 7 Magnetic Resonance Imaging (MRI)/computed tomography (CT) cavernosographies, 61 Doppler's sonographies, and 15 selective internal pudendal arteriographies. Hemodynamic phenomena were observed both intra-corporeally and extra-corporeally in patients who underwent penile venous stripping (n = 501), coil embolization (n = 6), and pudendal arterial stenting (n = 5).

OUTCOMES

This study confirms the existence of an independent penile fibro-vascular hydraulic environment within the human cardiovascular system.

RESULTS

The human penis contains an independent bi-layered fibrovascular assembly. Anatomical symmetry of bilateral arteries is rare on the arterial side. On the venous drainage side, there is one deep dorsal vein (DDV), two cavernosal veins, and four para-arterial veins, contrary to the conventional understanding of only a single DDV between the tunica albuginea and Buck's fascia. The penile venous drainage blood ultimately returns to pulmonary circulation.

CLINICAL IMPLICATIONS

Penile vascular surgery, particularly penile venous stripping, is shown to be the most physiologically appropriate method for restoring erectile function; contrarily, erection-related arterial stents, or venous embolization do not offer similar benefits.

STRENGTHS AND LIMITATIONS

This study's strength lies in its extensive analysis of a large repository of anatomical, physiological, radiographic imaging, and clinical vascular data; however, its retrospective nature represents a limitation.

CONCLUSION

This study demonstrates that the penile fibro-vascular assembly functions as an independent vascular system, substantially making it the last vascular compartment to be disclosed in the human body.

Septum of the penis - dissection, anatomical description and functional relevance

BACKGROUND

The septum of the penis or the pectiniform septum (from Latina pecten) is a connective structure that separates the two corpora cavernosa of the penis. It is formed through the joining of the circular fibers of the tunica albuginea, which envelops the corpora cavernosa. The septum neither completely separates, nor entirely joins the two corpora cavernosa.

RESULTS

We dissected the penile septum in 10 formalized bodies. The dissections were carried out using magnifying lenses, emphasizing the connective structures. We studied the structure of the septum using transverse and sagittal dissection planes. We identified the penile septum as a structure consisting of clusters of tendinous cords incompletely separating the two cavernous structures. The septum completely separates the two corpora cavernosa in its posterior segment. As we progress forward, the septum starts resembling the tendinous cords that attach to the papillary muscles of the heart. These cords are differentiated from the internal layer of the albuginea of each corpus cavernosum. We evaluated the opportunity of considering the anterior and posterior intercavernous ligaments as septal structures.

CONCLUSION

In this type of construction, the septum maintains both the hemodynamic and mechanical coherence of the cavernous structures and allows penile movement more efficiently than a continuous septal structure. The septum enables the lengthening of the penis and simultaneous filling with blood of both its corpora cavernosa through the transseptal vascular anastomosis. This allows for penile deformation during erection to be avoided. Our study also provides a description of the way the corpora cavernosa attach to the bulbus of corpus spongiosum.

Cardiometabolic Disorder and Erectile Dysfunction

Erectile dysfunction (ED), which is defined as the inability to attain and maintain a satisfactory penile erection to sufficiently permit sexual intercourse, is a consequence and also a cause of cardiometabolic disorders like diabetes mellitus, systemic hypertension, central obesity, and dyslipidemia. Although there are mounting and convincing pieces of evidence in the literature linking ED and cardiometabolic disorders, impairment of nitric oxide-dependent vasodilatation seems to be the primary signaling pathway. Studies have also implicated the suppression of circulating testosterone, increased endothelin-1, and hyperactivation of Ang II/ATIr in the pathogenesis of ED and cardiometabolic disorders. This study provides comprehensive details of the association between cardiometabolic disorders and ED and highlights the mechanisms involved. This would open areas to be explored as therapeutic targets in the management of ED and cardiometabolic disorders. It also provides sufficient evidence establishing the need for the management of cardiometabolic disorders as an adjunct therapy in the management of ED.

Tissue Engineering for Penile Reconstruction

The penis is a complex organ with a development cycle from the fetal stage to puberty. In addition, it may suffer from either congenital or acquired anomalies. Penile surgical reconstruction has been the center of interest for many researchers but is still challenging due to the complexity of its anatomy and functionality. In this review, penile anatomy, pathologies, and current treatments are described, including surgical techniques and tissue engineering approaches. The self-assembly technique currently applied is emphasized since it is considered promising for an adequate tissue-engineered penile reconstructed substitute.

Thinking About Pathomechanisms and Current Treatment of Erectile Dysfunction-"The Stanley Beamish Problem." Review, Recommendations, and Proposals

INTRODUCTION

Up to 50% of all men over 50 years of age suffer from erectile dysfunction. Since the late 1990s erectile dysfunction has been treated mostly with phosphodiesterase 5 inhibitors (PDE5I). Over the past 20 years, numerous scientific findings on the development of erectile dysfunction have been collected, which have so far received little attention in the treatment of erectile dysfunction.

OBJECTIVES

The objectives of this study were to review the existing medical literature on erectile dysfunction regarding physiology, pathophysiology, and especially therapeutic options beyond treatment with PDE5I and to enable a more effective and especially sustainable treatment for erectile dysfunction.

METHODS

A literature review was performed by using PubMed from 1985 to 2020 regarding the physiology, pathophysiology, and treatment of erectile dysfunction.

RESULTS

Since the end of the 1990s an enormous amount of knowledge has been gained about the physiology/pathophysiology of erection/erectile dysfunction. Based on these findings, numerous physical, drug, and holistic therapeutic options (beyond the application of PDE5I) have been developed for the treatment of erectile dysfunction. However, these are still relatively rarely used in the therapeutic concept of erectile dysfunction today.

CONCLUSION

Based on scientific findings of the last 20 years, there are numerous therapeutic approaches, including lifestyle modification, specific pelvic floor exercises, shock wave treatment, and the application of different supplements. The long-term treatment of erectile dysfunction should now go beyond the purely symptomatic use of PDE5I. W-D Beecken, M Kersting, W Kunert, et al. Thinking About Pathomechanisms and Current Treatment of Erectile Dysfunction-"The Stanley Beamish Problem." Review, Recommendations, and Proposals. Sex Med Rev 2021;9:445-463.

Erectile dysfunction and cancer: current perspective

Erectile dysfunction (ED) is one of the major but underreported concerns in cancer patients and survivors. It can lead to depression, lack of intimacy between the couple, and impaired quality of life. The causes of erectile dysfunction are psychological distress and endocrinal dysfunction caused by cancer itself or side effect of anticancer treatment like surgery, radiotherapy, chemotherapy and hormonal therapy. The degree of ED depends on age, pre-cancer or pre-treatment potency level, comorbidities, type of cancer and its treatment. Treatment options available for ED are various pharmacotherapies, mechanical devices, penile implants, or reconstructive surgeries. A complete evaluation of sexual functioning should be done prior to starting anticancer therapy. Management should be individualized and couple counseling should be an integral part of the anticancer treatment.

Functional reconstruction of injured corpus cavernosa using 3D-printed hydrogel scaffolds seeded with HIF-1α-expressing stem cells

Injury of corpus cavernosa results in erectile dysfunction, but its treatment has been very difficult. Here we construct heparin-coated 3D-printed hydrogel scaffolds seeded with hypoxia inducible factor-1α (HIF-1α)-mutated muscle-derived stem cells (MDSCs) to develop bioengineered vascularized corpora. HIF-1α-mutated MDSCs significantly secrete various angiogenic factors in MDSCs regardless of hypoxia or normoxia. The biodegradable scaffolds, along with MDSCs, are implanted into corpus cavernosa defects in a rabbit model to show good histocompatibility with no immunological rejection, support vascularized tissue ingrowth, and promote neovascularisation to repair the defects. Evaluation of morphology, intracavernosal pressure, elasticity and shrinkage of repaired cavernous tissue prove that the bioengineered corpora scaffolds repair the defects and recover penile erectile and ejaculation function successfully. The function recovery restores the reproductive capability of the injured male rabbits. Our work demonstrates that the 3D-printed hydrogels with angiogenic cells hold great promise for penile reconstruction to restore reproductive capability of males.

Injury of corpus cavernosa results in erectile dysfunction, and repair leading to restoration of function is difficult. Here the authors construct 3D printed hydrogel constructs seeded with HIF-1α-expressing muscle derived stem cells to restore corpus function in a rabbit model.

Development of a novel topical formulation of glyceryl trinitrate for the treatment of erectile dysfunction

Erectile dysfunction (ED), defined as the inability to initiate or maintain an erection sufficient for satisfactory sexual intercourse, is common, particularly in men aged ≥50 years. Existing treatments have significant limitations, and there remains a need for a fast-acting (to facilitate spontaneity during intercourse) and well tolerated local therapy. Topical glyceryl trinitrate (GTN) may meet this need because GTN undergoes rapid metabolism in penile smooth muscle and endothelial cells to produce nitric oxide, which plays a key role in the development of erection. This paper describes the rationale for the development of MED2005, a topical GTN formulation using DermaSys® technology, which is undergoing clinical trials for the treatment of ED. Pharmacokinetic studies have shown that MED2005 provides rapid delivery of GTN following application to the glans penis, and a Phase 2(a) trial in men with ED showed that MED2005 produced significant improvements in erectile function, compared with placebo. MED2005 was well tolerated in this trial, with only 21 cases of headache in 1003 intercourse attempts. It is anticipated that MED2005 will provide an effective therapy for ED, with a fast onset of action, good local tolerability, and fewer contraindications than phosphodiesterase 5 inhibitors, the current cornerstone of ED therapy.

Surgical niche for the treatment of erectile dysfunction

Penile erection implicates arterial inflow, sinusoidal relaxation and corporoveno-occlusive function. By far the most widely recognized vascular etiologies responsible for organic erectile dysfunction can be divided into arterial insufficiency, corporoveno-occlusive dysfunction or mixed type, with corporoveno-occlusive dysfunction representing the most common finding. In arteriogenic erectile dysfunction, corpora cavernosa show lower oxygen tension, leading to a diminished volume of cavernosal smooth muscle and consequential corporoveno-occlusive dysfunction. Current studies support the contention that corporoveno-occlusive dysfunction is an effect rather than the cause of erectile dysfunction. Surgical interventions have consisted primarily of penile revascularization surgery for arterial insufficiency and penile venous surgery for corporoveno-occlusive dysfunction, whatever the mechanism. However, the surgical effectiveness remained debatable and unproven, mostly owing to the lack of consistent hemodynamic assessment, standardized select patient and validated outcome measures, as well as various surgical procedures. Penile vascular surgery has been disclaimed to be the treatment of choice based on the currently available guidelines. However, reports on penile revascularization surgery support its utility in treating arterial insufficiency in otherwise healthy patients aged <55 years with erectile dysfunction of late attributable to arterial occlusive disease. Furthermore, it is noteworthy that penile venous surgery might be beneficial for selected patients with corporoveno-occlusive dysfunction, especially with a better understanding of the innovated venous anatomy of the penis. Penile vascular surgery might remain a viable alternative for the treatment of erectile dysfunction, and could have found its niche in the possibility of obtaining spontaneous, unaided and natural erection.

Penile implants: a look into the future

Inflatable penile prosthesis (IPP) has been around since the 1970’s as a durable and one-time cure for erectile dysfunction (ED). For the past 40 years, many changes have been made to make the device better and currently IPP boasts a high percentage of long-term patient satisfaction. The next paradigm shift in IPP treatment for ED is upon us. Funding for ED related medications and devices has been a hot topic in health policy over the last 10 years. This suggests that the device must improve and patient advocacy and education must increase for IPP to remain as a viable solution for ED. In this paper, we conduct a literature search for innovations in IPP and argue that IPP must constantly improve to compete with oral, injectable, shockwave, and potentially gene therapies.

A history of penile implants

Erectile dysfunction (ED) has long been described by physicians and patients, with treatments for ED proposed starting in the 8^th century BC. In the last 50 years, however, there have been many advances in medical and surgical management of ED, notably the introduction of the inflatable penile prosthesis (IPP) in 1973 and phosphodiesterase type 5 inhibitors (PDE5Is) in 1998. Here we review the evolution of the IPP from 1973 through the current day. The 3-piece device was first described in 1973 by Dr. F. Brantley Scott, who helped found American Medical Systems (AMS) to market and sell the device. In 1983, Mentor (now Coloplast) started marketing a competing device. AMS and Mentor have made multiple modifications to the device over the years, which have increased rigidity, durability and patient satisfaction, and have decreased surgical variability, post-operative infection and spontaneous inflation. Today, the IPP is a safe and effective option for many men who have failed medical therapies, with high satisfaction from both patients and partners.

Herb formula enhances treatment of impotent patients after penile venous stripping: a randomised clinical trials

Herbs have been regarded as aphrodisiacs in treating impotence for many centuries despite little true scientific evidence. Our latest refined penile venous stripping (PVS) technique is effective in treating impotence, although this procedure remains controversial. A synergic effect of PVS and oral herbs was confirmed in our practice but lacked rigorous scientific proof. The objective of this report was to review our experience with this combination. From August 2010 to May 2014, 263 males underwent PVS. Among these, 67 unsatisfied men chose additional salvage therapy and were randomly assigned to oral herbs (n = 35) or placebo treatment (n = 32) which replaced herb eventually. All were evaluated with the international index of erectile function (IIEF-5) scoring and our dual pharmaco-cavernosography. The pre-op IIEF-5 score for the herb group was 9.7 ± 3.7, post-operative 13.9 ± 3.3 and post-herb 19.6 ± 3.4, while the control group scores were as follows: pre-op 9.3 ± 4.1, post-op 14.5 ± 3.6, post-placebo 15.1 ± 3.5 and post-herb 19.9 ± 3.2. Although there was no significant difference between the two groups pre-operatively, post-operatively and post-herb, a statistically significant difference was found post-salvage therapy (19.6 ± 3.4 versus 15.1 ± 3.6, P < 0.001). It appears that the combination of oral herbs and PVS treatment provides an enhanced outcome to impotent patients refractory to medicine and unsatisfied with PVS monotherapy alone.

Tunical Outer Layer Plays an Essential Role in Penile Veno-occlusive Mechanism Evidenced from Electrocautery Effects to the Corpora Cavernosa in Defrosted Human Cadavers

OBJECTIVE

To determine the exact anatomical structure for establishing penile veno-occlusive function, we sought to conduct a hemodynamic study on defrosted human cadavers.

MATERIALS AND METHODS

Thirteen penises were used for this experiment, and 11 intact penises were allocated into the electrocautery group (EG, n = 6) and the ligation group (LG, n = 5). A circumcision was made on the penis to access the veins. Two #19 scalp needles were fixed in the 3 and 9 o'clock positions in the distal penis for colloid infusion and intracavernous pressure (ICP) monitoring, respectively. For the EG, the deep dorsal vein and cavernosal vein trunks were freed for 3-5 cm where at least 3 emissary veins were identified via opening Buck's fascia; these veins underwent electrocautery at 45 watts, while the ICP was maintained at 0, 50, 75, 100, 125, and 150 mmHg, respectively. For control, venous ligation was made but at the ICP of 150 mmHg. A tissue block including the emissary vein was then obtained for histological analysis.

RESULTS

Except all in the EG and those whose ICP exceed 125 mmHg in the EG, the sinusoids of the corpora cavernosa sustained varied fulgurated fibrosis in every specimen and the severity appeared reversely commensurate with the ICP regarding sinusoidal clumping and darkish bands (P <.02 and .01 respectively).

CONCLUSION

We conclude that the tunica albuginea can prevent the electrocautery damage to intracavernous sinusoids once the ICP reached a level corresponding to a rigid erection. The outer tunica plays an essential role in fulfilling the veno-occlusive mechanism.

Venous ligation: a novel strategy for glans enhancement in penile prosthesis implantation

Although penile implantation remains a final solution for patients with refractory impotence, undesirable postoperative effects, including penile size reduction and cold sensation of the glans penis, remain problematic. We report results of a surgical method designed to avoid these problems. From 2003 to 2013, 35 consecutive patients received a malleable penile implant. Of these, 15 men (the enhancing group) were also treated with venous ligation of the retrocoronal venous plexus, deep dorsal vein, and cavernosal veins. The remaining 20 men formed the control group, treated with only a penile implant. Follow-up ranged from 1.1 to 10.0 years, with an average of 6.7 ± 1.5 years. Although preoperative glanular dimension did not differ significantly between the two groups, significant respective difference at one day and one year postoperatively was found in the glanular circumference (128.8 ± 6.8 mm versus 115.3 ± 7.2 mm and 130.6 ± 7.2 mm versus 100.5 ± 7.3 mm; both P<0.05), radius (38.8 ± 2.7 mm versus 37.1 ± 2.8 mm and 41.5 ± 2.6 mm versus 33.8 ± 2.9 mm; latter P<0.01), and satisfaction rate (91.7% versus 53.3%, P<0.01) as well. Based on our results, selective venous ligation appears to enhance the glans penis dimension in implant patients.