interventional therapy and technique
Interventional therapy and techniques are based on radiological imaging. Guided by diagnostic imaging equipment such as ultrasound, CT, MRI, DSA, and X-ray, they utilize direct puncture or Seldinger interventional puncture and intubation techniques to diagnose and treat lesions. This approach offers advantages such as minimal trauma, ease of use, accurate positioning, and minimal complications, making it a key component of minimally invasive surgery.
Interventional radiology can be divided into two categories: transvascular and non-vascular, depending on the interventional approach.
- Transvascular interventional radiology uses imaging technology to guide catheters and other instruments through large blood vessels to the target organ for imaging diagnosis, biopsy, embolization, and other treatments.
- Non-vascular interventional radiology, with the assistance of imaging technology, bypasses blood vessels to directly perform puncture biopsies, catheter drainage, nerve block analgesia, and local tumor treatment.
- Transvascular Interventional Therapy Techniques
▌Transcatheter Intravascular Infusion (TII)
Drugs are injected directly into the blood vessels supplying the target organ via an interventional catheter, increasing local drug concentrations, enhancing efficacy, and reducing toxic side effects. Common Clinical Applications:
Malignant Tumors: Widely used for malignant solid tumors throughout the body, including palliative treatment, preoperative chemotherapy, postoperative preventive chemotherapy, or local chemotherapy for recurrent tumors.
Gastrointestinal Bleeding: Suitable for the diagnosis and hemostasis of upper and lower gastrointestinal bleeding, especially when the bleeding site is unclear. Contrast agents can be injected first to locate the bleeding, such as in cases of massive biliary bleeding from liver trauma, or bleeding in the stomach, duodenum, small intestine, or colon.
Organ Insufficient Blood Supply Lesions: Such as cerebral vasospasm, acute non-occlusive mesenteric vascular ischemia, peripheral vasospasm caused by drugs or frostbite, limb ischemia caused by atherosclerosis, and Raynaud’s disease. Antispasmodic drugs (such as nitroglycerin and papaverine) are injected into the blood vessels via an interventional catheter to relieve or improve ischemia. Arterial thrombosis: Thrombolytic agents (such as urokinase and streptokinase) are injected into target blood vessels via an interventional catheter to dissolve intravascular clots in the heart, brain, lungs, kidneys, intestines, and limbs. Thrombolytics are contraindicated in patients with gastrointestinal bleeding, traumatic bleeding, cerebral hemorrhage, infarction, pregnancy, postpartum period, and menstruation.
Transcatheter intraarterial chemoembolization (TACE or TAE)
TACE: A mixture of antitumor drugs and an embolic agent (such as iodized oil or gelatin sponge particles) is injected into tumor vessels, directly killing tumor cells and inducing ischemia, infarction, or necrosis. It is commonly used for palliative treatment of unresectable liver cancer. It is generally not used in patients with resectable liver cancer but with poor local arterial blood supply. It should be used with caution in patients with cancer thrombi in the main branches or trunks of the portal vein, splenomegaly, hypersplenism, and poor liver function. TAE: Commonly used embolic agents and materials include iodized oil, gelatin sponge particles, polyvinyl alcohol particles or spring coils, isobutyl cyanoacrylate, and vascular sclerosants (anhydrous ethanol, sodium morrhuate). It is primarily used to stop gastrointestinal hemorrhage, severe hemoptysis, and traumatic bleeding from the liver, spleen, kidney, retroperitoneum, and pelvis. It can also be used for aneurysms, hypersplenism, hepatosplenic arteriovenous fistulas, and various arteriovenous malformations (fistulas).
Percutaneous Transluminal Angioplasty (PTA)
A balloon catheter is inserted into the vascular lumen through percutaneous puncture to dilate and reshape the stenotic segment. Limited compression and expansion of the balloon causes tears in the intima and media of the stenotic segment. After dilation, the vessel diameter is maintained by blood pressure, and the damaged intima and media are repaired by platelet deposition, fibrosis, vascular smooth muscle cell proliferation, and endothelial regeneration. An intravascular stent can be used to consolidate and enhance the therapeutic effect. It is primarily indicated for atherosclerosis, Takayasu arteritis, fibromuscular dysplasia of the vascular wall, vascular webs, vascular malformations, anastomotic stenosis after vascular bypass surgery or graft anastomosis, membranous or segmental stenosis and occlusion of the inferior vena cava in Budd-Chiari syndrome, and hepatic vein stenosis and occlusion.
Transjugular intrahepatic portosystemic shunt (TIPS)
Under ultrasound guidance, a neck puncture is performed. An interventional catheter is inserted into the internal jugular vein. The catheter is advanced through the superior vena cava, right atrium, and inferior vena cava to the hepatic vein. Under X-ray guidance, the catheter is then punctured through the hepatic vein to enter the intrahepatic portal vein. The hepatic parenchymal channel between the hepatic vein and the portal vein is dilated and opened. Finally, a metal stent is placed to establish a shunt, diverting high-pressure portal venous blood directly to the inferior vena cava and reducing portal vein pressure. It is primarily indicated for the treatment of portal hypertension complicated by esophageal variceal bleeding and refractory ascites. It is particularly suitable for patients with poor liver function who cannot tolerate surgery or those awaiting liver transplantation. Percutaneous Intravascular Catheter-Based Drug Cartridge System Implantation
Using the Seldinger technique, a drug cartridge connector is superselectively placed within the target vessel. An external drug cartridge is then implanted subcutaneously, allowing for long-term drug delivery via this route.
Percutaneous Left Subclavian Artery Catheter-Based Drug Cartridge System Implantation: Primarily used to treat various solid tumors, such as lung cancer, liver cancer, and metastatic liver cancer.
Percutaneous Portal Vein Catheter-Based Drug Cartridge System Implantation: Primarily used for portal vein chemotherapy of metastatic liver cancer with poor blood supply, intravenous infusion of non-chemotherapeutic drugs (such as interferon, insulin, and pancreatic hormones) to enhance liver cell nutrition, and intraportal stem cell transplantation (such as islet cell and hepatocyte transplantation) to treat diabetes and end-stage liver disease.
- Commonly Used Non-vascular Interventional Techniques
▌Percutaneous Transhepatic Biliary Drainage (PTBD or PTCD)
Under ultrasound or X-ray guidance, percutaneous transhepatic puncture of the dilated intrahepatic bile duct is performed, typically at the intersection of the right midaxillary line and the 10th intercostal space, transversely toward the hepatic hilum. A catheter is then inserted for biliary drainage or decompression. This procedure can be used as a temporary external drainage for acute obstructive suppurative cholangitis that is inoperable. It can also be used to reduce jaundice and improve liver function before surgery for hilar cholangiocarcinoma or pancreatic head cancer, thereby enhancing surgical safety. For palliative treatment of inoperable hilar cholangiocarcinoma, it is best to insert a catheter from the dilated intrahepatic bile duct through the obstructing site of the tumor and into the common bile duct for internal drainage. In addition to PTBD, percutaneous balloon dilatation and percutaneous transhepatic biliary stent placement can be performed. The former is primarily used to treat benign biliary strictures. The latter typically involves inserting a rigid guidewire and catheter sheath into the bile duct through the drainage tube several days after bile drainage with post-transplantation catheterization (PTCD). Balloon dilatation is performed across the stricture, and a stent of the appropriate size is then placed over the guidewire. Commonly used stents or stents include mesh metal stents, spiral stents, Z-shaped metal stents, and plastic stents.
▌Percutaneous Implantable Microwave Tissue Coagulation (IMTC) and Radiofrequency Ablation (RFA)
Under ultrasound guidance, a microwave therapy antenna or radiofrequency probe is inserted into the target cancer tissue. The high temperature generated by microwaves or radiofrequency solidifies the tumor and surrounding tissue, causing rapid spherical or oblate spherical degeneration and necrosis.
▌Cryoablation (CSA)
The puncture method is the same as the above two methods, but CSA produces a cryogenic freezing effect below -172°C within the tumor tissue, causing coagulative necrosis of the cancer. Percutaneous Ethanol Injection (PEI) and Electrochemotherapy
Under ultrasound guidance, the central portion of the tumor is punctured and ethanol is injected or positive and negative electrodes are inserted, respectively, to induce coagulation necrosis of the tumor.
Percutaneous Catheterization
Under ultrasound or CT guidance, a puncture catheter is placed into the abscess cavity or localized area of effusion. This procedure is used to treat liver abscesses, intra-abdominal abscesses, pelvic abscesses, or effusions.
III. Complications of Interventional Surgical Techniques
Complications Related to Transvascular Interventional Therapy
Puncture complications: Common complications include bleeding and hematoma at the puncture site, intimal damage, or pseudoaneurysm formation. During puncture, careful attention should be paid to the patient’s coagulation status, and appropriate interventional instruments should be selected and carefully performed. Furthermore, the catheter may kink, break, or even form thrombi within the blood vessels. Dislodged emboli can lead to ectopic embolism.
Contrast Media Reactions: In rare cases, allergic reactions to contrast media or damage to the renal tubules may occur. Allergic reactions typically present as a rash. Renal tubular damage usually resolves within 1-2 weeks. Severe cases may result in laryngeal edema or anaphylactic shock. Patients with allergies, renal impairment, heart failure, diabetes, or advanced age should be given special attention.
Complications associated with non-vascular interventional techniques
Mainly include tissue and organ damage related to the puncture site. Examples include gallbladder or intestinal damage caused by radiofrequency ablation of liver tumors, lung injury caused by thoracentesis, and puncture tract bleeding. Other complications include puncture-induced abscess rupture and spread, and tumor seeding and dissemination.