Instrumentation and General Principles
Endovascular access is typically achieved via major arteries, after which a microcatheter is advanced to the pathological focus. For a successful procedure, it is critically important to select the correct occluding material:
- Particles (e.g., polyvinyl alcohol) are excellent for shutting down the capillary bed of tumors.
- Liquid agents — ethanol or specialized adhesive compositions (Histoacryl, Onyx). When alcohol is administered, temporary balloon occlusion of the vessel is often used, which helps control the flow and significantly reduces pain.
- Metallic coils (coils) are optimal for closing large defects, fistulas, or vessels feeding an aneurysm. Sometimes, stents are additionally placed to secure the coils in wide vessels.
Interventions require high surgical skill, as accidental entry of the embolic agent into collaterals (such as the colic arteries) can lead to severe ischemia of healthy tissues.
Interventions on the Kidneys and Urinary Tract
Renal tissue is extremely sensitive to hypoxia, so any non-target ischemia threatens the development of persistent post-embolization arterial hypertension. Interventional radiology has replaced surgery in treating a number of renal pathologies:
- Arteriovenous malformations (AVMs): These can be congenital or acquired (iatrogenic fistulas). They are divided into cirsoid (racemose, with multiple feeding branches) and cavernous (with a single feeding artery) types. They manifest with hematuria, hypertension, and, in cases of massive blood shunting, high-output heart failure. Embolization of AVMs is extremely complex and performed in specialized centers.
- Renal artery aneurysms: Occur against the background of atherosclerosis or fibromuscular dysplasia. Indications for treatment include lesions larger than 2 cm, symptomatic aneurysms, or those discovered in women planning a pregnancy.
- Iatrogenic injuries: Up to 10% of renal biopsies or percutaneous nephrostomies are complicated by pseudoaneurysms. If they enlarge or bleed, superselective coil occlusion is used.
- Angiomyolipomas: Benign tumors capable of causing acute pain and bleeding. The administration of microparticles leads to their complete devascularization.
| Abnormal | Features of the Intervention |
|---|---|
| Ureteral injury | In the case of a fistula with the iliac artery, a stent-graft is placed in the latter |
| Bladder bleeding | Embolization is indicated for hemorrhagic cystitis (following chemotherapy) |
| Renal artery avulsion | In blunt abdominal trauma, an attempt at angioplasty or stenting is possible |
Prostatic Artery Embolization (PAE)
Benign prostatic hyperplasia (BPH) is accompanied by urinary disorders in 40% of elderly men. If medical therapy fails, transurethral resection of the prostate (TURP) is the standard. However, prostatic artery embolization has emerged as a promising alternative.
The essence of the method lies in injecting microparticles (e.g., polyvinyl alcohol) into the tortuous and small arteries of the prostate. This causes local ischemia, as a result of which the prostate volume decreases by an average of 30%, reducing pressure on the urethra.
Advantages: preservation of sexual function and no risk of urinary incontinence. Challenges: the procedure is technically difficult (anatomical variability of vessels leads to a failure rate of up to 30%), and complications such as bladder wall ischemia or rectal bleeding may occur.
Uterine Artery Embolization (UAE)
Uterine fibroids are the most common tumor in women of reproductive age, reaching a frequency of 80% by menopause in certain ethnic groups. Although many cases are asymptomatic, large or submucosal nodes cause severe menorrhagia (more resistant than routine dysfunctional bleeding), pain, and pregnancy complications.
UAE is used as a third-line therapy — after the failure of medical treatments (NSAIDs, hormones) and local methods (Mirena intrauterine device, endometrial ablation). Uterine artery embolization effectively deprives fibroid nodes of blood supply, leading to their regression, and avoids radical hysterectomy or traumatic myomectomy.
Briefly: answers to topical questions
What specific complications can occur after prostatic artery embolization?
Specific complications associated with ischemia and damage to adjacent organs may occur following prostatic artery embolization. These include:
- Bladder wall ischemia — disruption of the blood supply to the organ wall.
- Rectal bleeding — discharge of blood from the rectum.
- Urethral pain — pain syndrome in the urethra.
What vascular anastomoses must be taken into account to prevent non-target embolization during UAE?
When planning embolization, it must be considered that the uterine artery forms anastomoses with other pelvic vessels. The main anastomoses include:
- Ovarian artery (a. ovarica) — forms a pronounced anastomosis with a branch of the uterine artery within the broad ligament of the uterus.
- Round ligament artery — anastomoses with the uterine artery along the lateral margin of the uterus.
Additionally, the general rule for using liquid embolizing agents requires accounting for potential anastomoses with the colic arteries.
What is the conservative treatment algorithm for uterine fibroids preceding the prescription of uterine artery embolization?
The conservative treatment algorithm for uterine fibroids involves the sequential use of pharmacological agents before moving on to uterine artery embolization, which belongs to the third line of therapy.
- First line — use of nonsteroidal anti-inflammatory drugs (NSAIDs), antifibrinolytics, and hormonal therapy.
- Second line — placement of a progesterone-releasing intrauterine device (Mirena coil) and endometrial ablation.
- Pharmacological correction — use of a progesterone receptor modulator (ulipristal acetate), although the drug was withdrawn due to the risk of liver injury.
If conservative therapy is ineffective, surgical treatment or embolization is considered.
What endovascular treatment methods exist for iatrogenic renal artery injuries?
Transcatheter embolization is used for the endovascular treatment of iatrogenic renal artery injuries leading to the formation of pseudoaneurysms and arteriovenous fistulas.
- Coil embolization (coils) is the method of choice for occluding the damaged vessel.
- Use of hemostatic sponge (Gelfoam) — can be used either independently or in combination with coils.
The procedure requires the mandatory use of superselective techniques with coaxial catheters for the most distal occlusion possible and the preservation of healthy renal tissue.
Class and exam questions
What are the risks of non-target embolization in renal treatment?
Ischemia or accidental loss of healthy renal parenchyma can provoke the development of severe post-embolization arterial hypertension.
When is surgery necessary for a renal artery aneurysm?
Indications include a lesion size greater than 2 cm, the presence of clinical symptoms (pain, hematuria), or planning a pregnancy.
Why is balloon occlusion used during ethanol injection?
Temporary occlusion of the artery with a balloon stops blood flow, which prevents alcohol from washing out into other areas and significantly reduces the intensity of pain during the procedure.
What else to study on this topic
- Features of neuroradiological systems (e.g., Solitaire EV3 stents) for complex anatomy
- Hemorrhagic cystitis: pathogenesis of bladder vessel damage following chemotherapy
- Mechanisms of heart failure development in renal arteriovenous malformations
- Comparative efficacy of PAE and transurethral resection of the prostate (TURP)
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Other topics in the "Interventional radiology" section
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