Interventional vascular techniques

  A wide range of interventional vascular techniques has developed from basic angiographic principles and has had a profound impact on many aspects of medicine and surgery.

  Vascular therapy

By selective arterial cannulation it is possible to deliver a high local dose of a chemotherapeutic agent to the feeding vessels of a tumour. This technique has been used with success for liver turnouts, particular hepatocellular carcinoma, metastatic colorectal cancer and ocular melanoma.

There has been a resurgence of interest in the potential of low dose intra-arterial infusion of thrombolytic agents in peripheral arterial thromboembolic occlusion. The choice of therapy between surgical embolectomy and thrombolysis is controversial.

In patients with recurrent or threatened pulmonary embolisation from lower extremity or pelvic thrombus, inferior vena caval filters may be inserted percutaneously, from either a femoral or jugular approach to prevent the passage of a major embolus. A femoral approach is appropriate if the thrombus does not extend proximally into the inferior vena cava and if the contralateral femoral and pelvic veins are patent. Otherwise, a jugular approach is indicated, assuming the superior vena cava is patent.

Management of vascular obstruction

Percutaneous transluminal angioplasty

  This technique of balloon dilatation of a vascular stenosis, with the aim of increasing blood flow and improving perfusion, has had a profound impact on the treatment of vascular disease. Initially described by Dotter and Judkins in 1964, the technique has undergone many modifications and now provides a lower risk alternative treatment to surgical bypass graft.

  Indications include:

   peripheral vascular disease with relatively short occlusions (10—15 cm in length);

   ischaemic heart disease with coronary artery stenosis;

   hypertension or chronic renal failure with renal transplant artery stenosis;

   mesenteric/coeliac artery stenosis.

The technical success rate for femoral and popliteal angioplasty is between 85 and 95 per cent for stenoses with a 20—70 per cent patency rate at 5 years (Fig. 2.41). Complications include local haemorrhage and haematoma, false aneurysm formation at the puncture site, subintimal dissection and arterial perforation. The incidence of peripheral embolisation of atheromatous deposits is low, reported as between 3 and 5 per cent of cases and rarely resulting in clinically apparent ischaemia.

  Vascular stenting

  In 1988, Palmaz reported the use of intravascular stents in atherosclerotic arterial stenosis. The therapeutic potential of expanding metal stents in vascular disease is great and stents are being successfully used in renal ostial stenosis, abdominal aortic aneurysm repair, coronary artery disease and other major peripheral vessels. A major problem of intravascular stents is their thrombogenic potential as fibrin and platelets are deposited within the mesh of the stent. This can be inhibited by anticoagulation and over a period of weeks endothelialisation of the stent occurs. It is likely that with further technical developments, stents will be developed that will be antithrombotic, encourage endothelialisation and inhibit neo-intimal hyperplasia.

Transjugular intrahepatic porto-systemic shunt

(TIPSS)

A particular use of expanding metal stents has been in the development of TIPSS, which involves the percutaneous creation of a communication between the portal and hepatic venous systems for the relief of portal hypertension (Fig. 2.42). This procedure was first performed by Richter in 1988 and is now firmly established as an alternative to surgery in patients with recurrent variceal bleeding who are resistant to sclerotherapy or endoscopic banding. The technical success rate is over 90 per cent. The major complication is hepatic encephalopathy which can develop following the procedure. Shunt occlusion may develop, usually as a result of intimal hyperplasia. This may require re-intervention with balloon dilatation or a second stent insertion.  

Therapeutic embolisation

Deliberate vascular embolisation with the aim of occluding a vessel can be achieved using a variety of different materials including gelatin, sponge fragments, polyvinyl alcohol foam particles (PVA) and spiral metal coils.

Arterial embolisation may be used in the treatment of:

   acute haemorrhage;

   tumour therapy;

   arterio-venous malformations;

   hypersplenism;

   priaprism.

Venous embolisation is used for treatment of:

   gastro-oesophageal varices;

   testicular varicocele.

  The technique can be performed under local anaesthetic and requires a highly skilled radiologist to position selectively the catheter. The technique is not without risk as accidental embolisation of adjacent normal structures may occur. Tissue necrosis following the procedure may cause pain and fever due to tissue infarction and occasionally results in abscess formation.