Challenges and Techniques for Prostatic Artery Embolization

Prostate artery embolization (PAE) has evolved into an encouraging minimally invasive option for patients suffering from a variety of prostatic issues, including lower urinary tract symptoms (LUTS) secondary to benign prostatic hyperplasia (BPH), hematuria of prostatic origin, and prostate cancer. After initial medical therapy, transurethral resection of the prostate (TURP) still remains the gold standard of surgical treatment. However, its role is undermined by the associated risks of bleeding and lasting sexual dysfunction. With the considerable prevalence of BPH and an associated impact on national health care of $3 billion,¹ less invasive options and minimally invasive procedures have been continually examined. Since first performing PAEs in 2008, the multidisciplinary team at the University of Sao Paulo has been encouraged by patient outcomes. The University of Miami has been offering PAE since 2014 and over 125 patients with BPH have been treated.

Prostate Artery Anatomy

Technically, PAE is challenging. Knowledge of anatomical features to identify and catheterize target arterial branches is paramount to achieve the best clinical outcomes (Figure 1). Unnecessary catheterization increases procedure time and radiation exposure, with isolated reports of radiodermatitis.² The prostate receives its arterial supply via the medial and the capsular/lateral branch, but is variable among patients.³ de Assis et al proposed an angiographic classification of prostate artery anatomy and analyzed 286 pelvic sites to find that most inferior vesical arteries and their prostatic branches arise from the internal pudendal artery.⁴ Cone-beam computed tomography (CBCT) angiography has been utilized to evaluate the many variants of the prostatic artery.⁵ With direct contrast injection and 3-dimensional angiogram, subtle prostatic feeders are better identified when compared to digital subtraction angiography (DSA) and CT angiography. Further studies must be done to clarify its role in PAE (Figure 2). 

Transfemoral Access vs Transradial Access

Traditionally, PAE has been performed via a transfemoral approach (TFA). Originally developed for percutaneous coronary interventions, a transradial approach (TRA) for PAE has garnered increased interest. Evidence has suggested that TRA results in shorter postprocedure hospital stays, decreased access-site complications, and an improved patient satisfaction. This method would also allow patients to ambulate immediately post PAE, which could facilitate urination. The distance from the forearm to pelvis along with the arterial tortuosity and previously mentioned variant anatomy has deterred initial attempts for PAE via TRA. Further, prior to selecting TRA patients, collateral circulation must be adequate as determined using a Barbeau test (ie, a modified Allen’s test with a pulse-oximetry device). Isaacson et al recently published a series of 19 patients who underwent PAE using TRA.⁶ The only exclusion criterion was a type D Barbeau waveform. Bilateral PAE was achieved in all patients and none experienced major complications. The only minor complications were 2 patients with small (<5 cm) hematomas at the access site and 1 patient with increased wrist pain. 

The University of Miami has been performing PAEs via TRA since February 2016 and has treated more than 40 patients using this method. To date, there have only been 2 cases that were not technical successes (defined as bilateral embolization). The TRA patients have been compared with initial TFA patients and advanced TFA patients in order to account for the learning curve associated with performing PAEs. All TRA patients have not needed pre-PAE pelvic angiograms and have had decreased procedure times, fluoroscopy times, and total radiation doses when compared with all TFA patients. No major complications have occurred in any TRA patients and no significant difference in minor complication rates have been found when compared with initial and advanced TFA patients. The exclusion criteria for TRA-PAE has been patient height (>6 ft), type D Barbeau waveform, and radial artery diameter <2.0 mm. At the time of this article, there have been 2 patients with radial artery diameters <2.0 mm. These 2 patients were accessed via ulnar artery and experienced no major complications. 

Indicated Patient Populations

One of the most promising benefits of PAE has been its efficacy in a variety of patient populations. PAE has been performed in patients with both small and large prostates. TURP in larger gland sizes, especially in prostate volumes >80 cm³, is associated with longer operative times and an increased risk of bleeding and anesthesia-related complications. In contrast, PAE has been demonstrated to be safe and efficacious in varying prostate sizes with no major complications.⁷ One case report has even documented the efficacy of PAE in a patient with a prostate volume of 571 cm³ that yielded symptomatic improvement and no complications.⁸ Further, PAE has demonstrated its role in elderly patients (≥75 years old).⁹ In a prospective study done by Wang et al, despite this cohort of patients having a higher prevalence of hypertension, heart disease, chronic obstructive pulmonary disease, urinary retention and antiplatelet agent use than younger patients, they experienced no major complications and a significant improvement in International Prostate Symptom Score (IPSS) after PAE.⁹ Conversely, TURP has been associated with an increased risk of complications in patients with multiple comorbidities.

PAE and Lower Urinary Tract Symptoms Due to Benign Prostatic Hyperplasia 

In terms of symptomatic improvement in patients suffering from LUTS, PAE has continued to demonstrate its value. Most recently, a meta-analysis by Cizman et al examined PAE in the setting of short- to mid-term follow-up.¹⁰ Over 500 PAE patients were assessed to determine the efficacy and safety of the procedure. At 12 months, IPSS and quality of life (QOL) score decreased by 59% and 56%, respectively, with no significant change in International Index of Erectile Function scores. Prostate-specific antigen (PSA) level and postvoid residual (PVR) volume had the largest decrease within the first 6 months after PAE. Peak flow rate also increased by more than 90% at 12 months. The analysis suggests that the degree and rate of morbidity associated with PAE is more favorable than that of TURP. When compared with adverse events of TURP,¹¹ PAE has a lower incidence of transfusion, UTI, and urethral stricture. PAE has also been demonstrated to have a minimal association with ejaculatory and erectile dysfunction when compared with TURP.

Medium- and long-term outcomes post PAE were recently analyzed by Pisco et al; 630 patients were examined at 18 to 78 months.¹² Medium-term follow-up was defined as 18 to 36 months and long-term follow-up was defined as 36 to 78 months. Long-term follow-up patients had a 76.3% success rate with a lack of sexual dysfunction or urinary incontinence. The study noted that most clinical failures occurred prior to 18 months post PAE. As time post-PAE increased, the incidence of clinical recurrence decreased. Among all patients, there was a mean improvement in IPSS, QOL, and erectile function at both medium-term and long-term follow-up. Correspondingly, there was a decrease in prostate volume and PSA during these time frames. 

PAE and Hematuria

Prostatic hematuria is usually associated with BPH, iatrogenic urological trauma, or radiation therapy. Traditionally, it is treated conservatively with increased fluid intake, indwelling catheterization with bladder irrigation, and medical therapy. However, when these interventions fail, refractory hematuria is life threatening. Prostate artery embolization has been shown to be an option for these patients. Although distinct prostatic hemorrhage is rarely seen on angiography, PAE is successful by obtaining complete arterial occlusion. By utilizing a super-selective approach, control or cessation of hematuria within 1 to 3 days is achieved in 83% to 100% of patients.¹³  

PAE and Prostate Cancer

After skin cancers, prostate cancer is the most common cancer affecting men in the United States. Patients with advanced prostate cancer can present with or develop gross hematuria, urinary obstruction, and ureteral obstruction. Conventionally, this is treated with hormonal and other pharmacologic therapy. In refractory cases, surgical interventions have been performed. Although a large-scale trial has not yet been performed, PAE may play a role in the treatment of prostatic hemorrhage related to advanced prostate cancer.

Increased prostate volume has been associated with an increase in urinary complications post prostatectomy.¹⁴ In this sense, PAE may serve as a bridge to decrease prostate size and improve symptoms prior to prostatectomy or other surgical options. The University of Miami is conducting a prospective single-arm study to evaluate the feasibility of PAE in the setting of prostate cancer as an adjunct to prostatectomy. 

Possible Complications

Although minimal, PAE has adverse effects post procedure. For patients without indwelling catheters, urethral burning during voiding and frequent urination have been the most common symptoms after PAE. However, these effects usually resolve within a week and can be treated with non-opioid analgesic medications. More serious complications are associated with non-target embolization to the bladder, rectum, and penis. Ischemia to these organs is always possible and must be avoided through proper mapping via CBCT, microcatheterization for distal embolization, and calibrated microspheres for predictable embolization. 

The Future of PAE 

Prostate artery embolization must be continually investigated in order to validate these encouraging observations. Future larger studies with long-term follow-up along with randomized control trials are currently underway. Although current data suggest that PAE is a promising procedure for interventional radiologists, a concerted effort to include a multidisciplinary team of urologists, diagnostic radiologists and interventional radiologists will provide patients with optimum care.

Acknowledgments. The authors would like to extend special thanks to Vishal Sinha, 4th year medical student at the University of Miami, for his assistance in drafting this article.

References

1. Wei JT, Calhoun E, Jacobsen SJ. Urologic diseases in America project: benign prostatic hyperplasia. J Urol. 2005;173:1256-1261.
2. Laborda A, De Assis AM, Ioakeim I, Sánchez-Ballestín M, Carnevale FC, De Gregorio MA. Radiodermitis after prostatic artery embolization: case report and review of the literature. Cardiovasc Intervent Radiol. 2015;38:755-759.
3. Bilhim T, Pisco JM, Rio Tinto H. Prostatic arterial supply: anatomic and imaging findings relevant for selective arterial embolization. J Vasc Interv Radiol. 2012;23:1403-1415.
4. de Assis AM, Moreira AM, de Paula Rodrigues VC, et al. Pelvic arterial anatomy relevant to prostatic artery embolisation and proposal for angiographic classification. Cardiovasc Intervent Radiol. 2015;38:855-861.
5. Wang MQ, Duan F, Yuan K, Zhang GD, Yan J, Wang Y. Benign prostatic hyperplasia: cone-beam CT in conjunction with DSA for identifying prostatic arterial anatomy. Radiology. 2017;282:271-280. Epub 2016 Jul 28.
6. Isaacson AJ, Fischman AM, Burke CT. Technical feasibility of prostatic artery embolization from a transradial approach. AJR Am J Roentgenol. 2016;206:442-444.
7. Bagla S, Smirniotopoulos JB, Orlando JC, van Breda A, Vadlamudi V. Comparative analysis of prostate volume as a predictor of outcome in prostate artery embolization. J Vasc Interv Radiol. 2015;26:1832-1838.
8. Bhatia S, Kava B, Pereira K, Kably I, Harward S, Narayanan G. Prostate artery embolization for giant prostatic hyperplasia. J Vasc Interv Radiol. 2015;26:1583-1585.
9. Wang MQ, Wang Y, Yan JY, et al. Prostatic artery embolization for the treatment of symptomatic benign prostatic hyperplasia in men ≥75 years: a prospective single-center study. World J Urol. 2016;34:1275-1283.
10. Cizman Z, Isaacson A, Burke C. Short- to midterm safety and efficacy of prostatic artery embolization: a systematic review. J Vasc Interv Radiol. 2016;27:1487-1493.
11. Omar MI, Lam TB, Alexander CE, et al. Systematic review and meta-analysis of the clinical effectiveness of bipolar compared with monopolar transurethral resection of the prostate (TURP). BJU Int. 2014;113:24-35.
12. Pisco JM, Bilhim T, Pinheiro LC, et al. Medium- and long-term outcome of prostate artery embolization for patients with benign prostatic hyperplasia: results in 630 patients. J Vasc Interv Radiol. 2016;27:1115-1122.
13. Pereira K, Halpern JA, McClure TD, et al. Role of prostate artery embolization in the management of refractory haematuria of prostatic origin. BJU Int. 2016;118:359-365.
14. Boczko J, Erturk E, Golijanin D, Madeb R, Patel H, Joseph JV. Impact of prostate size in robot-assisted radical prostatectomy. J Endourol. 2007;21:184-188.

Editor’s note: This article first appeared in the Synergy Daily conference newspaper, available to attendees of the Synergy Miami interventional oncology meeting in November 2016. This article did not undergo peer review. Dr Bhatia can be reached at sbhatia1@med.miami.edu.

Suggested citation: Bhatia S, Carnevale FC. Challenges and techniques for prostatic artery embolization. Articles from the official show daily for Synergy 2016. Intervent Oncol 360. 2017;6(2):E14-E19.