Epidemiology and pathophysiology of BPH
BPH has a high prevalence rate amongst ageing men, with >50% affected >50 years and >90% >80 years [1,2]. It contributes to, but is not the sole cause of, LUTS in this patient group.
BPH is characterised histopathologically by an increased number of epithelial and stromal cells in the periurethral area of the prostate (Fig. 1).
Fig. 1
References: National Cancer Institute
Whilst there is no clear consensus on the pathophysiology of BPH, several theories have been advanced, and it is clear that androgens play a major role. Prostatic enlargement depends on the hormone dihydrotestosterone (DHT) which is produced within the prostate through metabolisation of circulating testosterone by type II 5-alpha-reductase. Levels of DHT remain high with ageing, despite levels of serum testosterone decreasing, thus stimulating protein synthesis and cell hyperplasia.
PAE has been shown to induce prostate volume reduction in both animal and human models by reducing blood supply to the gland [3-5], thus inducing ischaemia and organ shrinkage.
Anatomy
The prostatic artery is a visceral branch of the internal iliac artery (IIA). Various classification systems have attempted to simplify the branching pattern of the IIA. In the most common pattern, the IIA divides into two branches, the posterior division and the anterior division (or gluteal-pudendal trunk) [6]. The anterior division bifurcates into the inferior gluteal artery and the internal pudendal artery.
Fig. 2
The prostatic artery most commonly arises from the internal pudendal artery, but can arise more proximally from the anterior division of the IIA or from the superior vesical artery (Fig. 2). Bilhim et al., found a solitary prostatic artery in 60% of cases, whereas in 40% of cases two prostatic arteries were found [7].
Advantages of using a transradial approach
In the original papers describing PAE, a transfemoral approach was used [8,9]. There has been recent interest in adopting a transradial approach for procedures such as uterine artery embolisation [10], and more recently for PAE itself [11]. There are several perceived benefits of using a transradial approach including:
· Increased patient comfort
· Minimal bedrest after procedure
· Reduced radiation dose to the operator
Review of contraindications
There are several contraindications to using a transradial approach. The only absolute contraindication we are aware of is complete occlusion of the ulnar artery or palmar arch in which the collateral circulation would not be sufficient should the radial artery be compromised. This can be evaluated using a simple Barbeau test.
Relative contraindications include:
· Radial artery occlusion/stenosis
· Subclavian artery occlusion/stenosis
· Current or future haemodialysis
· Radial artery loop
Diagnostic imaging
Our patients underwent preprocedural imaging with pelvic CT angiography and intraprocedural imaging with cone-beam CT (Fig. 4).
Embolisation technique
- Patient admitted on the day of the procedure.
- Unilateral approach into the left radial artery with a standard entry needle and placement of a 5Fr sheath.
- Radial cocktail administered (verapamil 2.5mg, GTN 200 mcg, heparin 2000iu).
- IIA catheterised using a 4Fr catheter.
- Angiography of the anterior division of the IIA performed to visualise the anatomy of the prostatic artery (Fig. 3).
Fig. 3
- The prostatic artery was selectively catheterised and cone-beam CT performed (Fig. 4).
Fig. 4
- With the tip of the catheter within the prostatic artery, embolisation was performed using 250μm Embozene microspheres.
- The end point chosen for embolisation was slow flow within the prostatic artery (Fig. 5).
Fig. 5
- The technique was repeated on the contralateral prostatic artery.
- Helix radial artery compression device applied to the puncture site and removed after 75 minutes.
Outcomes (including complications)
In two out of three cases, the contralateral artery could not be embolised. In one case this was due to significant atherosclerosis which had been identified and reported on pre-treatment CT angiography. In one case it was due to the presence of multiple shunts between the prostatic artery and the internal pudendal artery (Fig. 6).
Fig. 6
There were no immediate postprocedural complications, in particular at the radial puncture site.
Our patients have yet to attend follow-up, however to our knowledge no early complications have been reported.