Clinical case: Angiomyolipoma embolization
Let us examine the procedure using the example of treating a large angiomyolipoma (angiomyolipoma, AML) originating from the interpolar region of the kidney.
- Diagnostic stage: Computed tomography (CT) visualizes a massive neoplasm. Pre-intervention baseline angiography demonstrates pronounced tumor vascularization.
- Technique: The physician performs superselective catheterization of the target segmental artery supplying the lesion. A coaxial microcatheter (coaxial microcatheter) is used for precise navigation.
- Result: The embolic agent is injected through the placed microcatheter. Polyvinyl alcohol (polyvinyl alcohol) is used in this clinical case. The final control angiogram clearly demonstrates a reduction in the vascularization of the angiomyolipoma—blood flow within the tumor has been halted.
Classification of embolic agents
Various classes of materials are used for vascular occlusion, the choice of which depends on the blood flow velocity and the purpose of the intervention.
1. Metallic coils Their mechanism of action is fully analogous to surgical ligation of a vessel. Critical rule: precise knowledge of the patient's vascular anatomy is required prior to coil placement. This prevents retrograde filling of the pathological focus with blood via a network of collateral vessels.
- Indications: cessation of profuse haemorrhage, exclusion of true aneurysms and pseudoaneurysms from the systemic circulation.
2. Liquid embolic agents This group is divided into two subcategories:
- Sclerosants: absolute alcohol (absolute alcohol) and sodium tetradecyl sulphate (sodium tetradecyl sulphate, STD). Optimal for venous embolization (e.g., in the treatment of pelvic congestion syndrome) and low-flow vascular malformations.
- Glue compositions and new polymers: n-butyl-2-cyanoacrylate (n-butyl-2-cyanoacrylate) and the modern agent Onyx. Used in complex hemodynamic conditions—high-flow arteriovenous malformations and visceral artery aneurysms (VAAs).
Thrombolysis: Dissolution of blood clots
Thrombolysis (thrombolysis) is the process of targeted dissolution of blood clots directly within the lumen of the affected artery or vein.
Procedure technique: The intervention is performed in a minimally invasive manner. The physician advances a catheter directly into the thickness of the thrombus. An injection or continuous infusion of a thrombolytic agent (lytic agent) is performed through it.
Timeline and monitoring: Although successful clot lysis is sometimes achieved quite rapidly, standard clinical practice is a prolonged infusion of the drug over an extended period—from 24 to 48 hours. Throughout the treatment process, patients require strict monitoring: periodic check angiography (check angiography) is performed to visually assess the effectiveness of thrombus dissolution and the completeness of vascular bed restoration.
Briefly: answers to topical questions
What embolic agents are used for endovascular treatment of renal angiomyolipoma?
In the presented clinical case, polyvinyl alcohol (PVA) was used for the endovascular treatment of renal angiomyolipoma. It is classified as a permanent embolic particle. The embolic agent was administered during superselective catheterization of the segmental artery supplying the tumor using a coaxial microcatheter. The control angiogram showed a reduction in the angiomyolipoma's vascularization. Precise knowledge of vascular anatomy is necessary to prevent retrograde filling of the pathological focus through collateral vessels.
What are the absolute contraindications to local thrombolysis?
The provided sources do not detail specific absolute contraindications specifically for local catheter-directed thrombolysis. Surgery within the preceding 10–14 days is indicated as an absolute contraindication to thrombolytic therapy in massive pulmonary embolism due to the risk of fatal bleeding in the early postoperative period. Catheter-directed thrombolysis requires dynamic monitoring of hemoglobin, platelets, and fibrinogen at least once every 24 hours.
Class and exam questions
Why is it so important to know the vascular anatomy during coil embolization?
This is necessary to prevent retrograde filling of the pathological focus (or aneurysm) via collateral vessels.
What agents are used for the embolization of high-flow lesions?
In such cases, glue compositions (n-butyl-2-cyanoacrylate) and modern liquid agents such as Onyx are used.
How exactly is the drug administered during thrombolysis?
The thrombolytic drug is administered via injection or infusion through a catheter previously advanced directly into the thickness of the thrombus itself.
What else to study on this topic
- Features of superselective catheterization with a coaxial microcatheter
- Use of sclerosants in pelvic congestion syndrome
- Tactics for excluding visceral artery aneurysms (VAAs) from the circulation
- Interpretation of control angiography in assessing thrombolysis efficacy
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