Interventional Radiology PDF

Thrombolysis Stent / shunt placement  Objectives of the lecture By the end of lecture students should be: ▀Summarize the basic information concerning thrombolysis and stent / shunt placement ▀ Develop the ability of performance thrombolysis and stent / shunt placement ▀ Illustrate the pur...

Thrombolysis Stent / shunt placement  Objectives of the lecture By the end of lecture students should be: ▀Summarize the basic information concerning thrombolysis and stent / shunt placement ▀ Develop the ability of performance thrombolysis and stent / shunt placement ▀ Illustrate the purpose, indication, and necessary patient preparation for thrombolysis and stent / shunt placement  Thrombolysis This is the use of drugs to break up a blood clot by breaking down the fibrin holding the clot together. Thrombolysis is not usually clinically indicated >6 weeks after the thrombotic event  Equipment There are different techniques for performing thrombolysis, and the equipment varies according to the strategy being used: Ultrasound to guide puncture Mini access kit Basic angiography set Infusion catheters: a 4F straight catheter with side holes is suitable in most cases A pump suitable for arterial infusion Co-axial systems or microcatheters may be helpful Pulse spray techniques require special catheters and pumps  Approach As always, the shortest most direct approach is usually the best, as it affords the greatest scope for adjunctive intervention. In some cases, the best approach will involve direct puncture of a bypass graft. If possible, avoid the brachial approach, as there is a risk of peri- catheter thrombus embolizing to cause CVA. Arterial puncture: At the risk of stating the obvious, try to make a single arterial puncture. Thrombolysis is sure to lead to bleeding from any extra puncture sites. This is a good time to use ultrasound to ensure safe arterial puncture. Use a mini access kit to keep the size of any unwanted holes to a minimum. Infra-inguinal grafts almost invariably arise from the anterior aspect of the common femoral artery (CFA). Arterial puncture must be sufficiently proximal to allow manipulation of a shaped catheter (Cobra or RDC) to direct a straight guidewire toward the graft origin. Direct prosthetic graft puncture: Ultrasound guidance is still the preferred option. When the graft is palpable, fix it between forefinger and thumb and then perform a single wall puncture in the conventional manner. There is a very distinctive give and fall in resistance as the needle enters the graft lumen. Depending on the direction of catheterization, direct graft puncture will preclude accessing either the origin or the outflow. Retrograde lysis often occurs but sometimes it is necessary to make a second puncture from the other end of the graft – the ‘crossed catheter technique’.  Complications Unfortunately, complications of thrombolysis are not rare and may be life- threatening. Complications increase with the age of the patient, the duration of treatment and the dose of the lytic agent. Stop the infusion and the heparin if a complication develops. CVA: perform an urgent CT scan if there are signs suggestive of CVA. If there is thrombotic CVA, seek expert neurological opinion and discuss whether to continue with thrombolysis; hemorrhage means game over. Puncture site haematoma: perform manual compression, check that the sheath has not been displaced and consider exchanging for a larger sheath.  Complications Significant bleeding: consult a haematologist for advice if bleeding persists after the infusion is stopped. Check the clotting and try to intervene early before the patient becomes unstable. Resuscitate the patient with blood and fresh frozen plasma (FFP) as necessary. Surgical intervention may be required. Acute clinical deterioration with increased pain: reassess, this is often due to distal embolization of thrombus which occurs in up to 5% of patients. Macroemboli may lyse spontaneously or can be aspirated. Microemboli are much more serious and may cause trash foot. Reperfusion syndrome: this is caused when there has been prolonged and severe ischaemia. Adult respiratory distress syndrome and renal failure are common sequelae and there is a high mortality.  Mechanical thrombectomy Mechanical thrombectomy uses special catheters to macerate the thrombus. The residue is either small enough to pass through the distal circulation or is aspirated. The catheter has to be appropriately sized for the vessel and large sheaths may be necessary. These devices work best with fresh thrombus and small acute emboli Catheter-directed intrathrombus thrombolysis (CDT), which refers to the infusion of a fibrinolytic drug directly into the venous thrombus via a multi–side-hole catheter that is embedded in the thrombus using imaging guidance. Mechanical thrombectomy devices are capable of macerating thrombus, and some devices (Angio Jet/Angiovac Cleaner XT & 15/EKOS/Penumbra Indigo System/Trerotola) Two of these techniques are performed with use of the AngioJet. With the “powerpulse” technique the AngioJet is first used to forcefully pulse-spray a bolus dose of the thrombolytic drug directly into the thrombus  May-Thurner syndrome is caused when the left iliac vein is compressed by the right iliac artery, which increases the risk of deep vein thrombosis (DVT) in the left extremity. DVT is a blood clot that may partially or completely block blood flow through the vein  Collateral circulation is a network of tiny blood vessels, and, under normal conditions, not open.... This allows blood to flow around the blocked artery to another artery nearby or to the same artery past the blockage, protecting the heart tissue from injury. Stent / shunt placement Transjugular Intrahepatic Portosystemic Shunt (TIPS) A transjugular intrahepatic portosystemic shunt (TIPS) is a percutaneously created connection within the liver between the portal and systemic circulations. A TIPS is placed to reduce portal pressure in patients with complications related to portal hypertension. This procedure has emerged as a less invasive alternative to surgery in patients with end-stage liver disease. ▲The goal of TIPS placement is to divert portal blood flow into the hepatic vein, so as to reduce the pressure gradient between portal and systemic circulations. ▲ Shunt patency is maintained by placing an expandable metal stent across the intrahepatic tract.  INDICATIONS Acute variceal bleeding that cannot be successfully controlled with medical treatment, including sclerotherapy. Recurrent and refractory variceal bleeding. Therapy for refractory ascites. Portal decompression in patients with hepatic venous outflow obstruction (Budd-Chiari syndrome, a blockage in one or more veins that carry blood from the liver back to the heart) or hepatorenal syndrome.  INDICATIONS cont.… Initial therapy of acute variceal hemorrhage Initial therapy to prevent initial or recurrent variceal hemorrhage Reduction of intraoperative morbidity during liver transplantation. ❖ Right-sided heart failure with increased central venous pressure ❖ Polycystic liver disease ❖ Severe hepatic failure □ Active intrahepatic or systemic infection (bacteria can colonize the stent, causing persistent infection) □ Severe hepatic encephalopathy poorly controlled with medical therapy □ Hypervascular hepatic tumors □ PV thrombosis (Although PV thrombus may make the procedure more technically demanding, it is not an absolute contraindication to TIPS placement.) ▪ prophylactic broad-spectrum antibiotics. ▪ Appropriate resuscitation with fluid and blood products. ▪ Portal vein (PV) patency should be confirmed prior to attempts at TIPS placement by Doppler sonography, arterial portography and MRI. ▪ In Patients with cirrhosis severe coagulopathy should be addressed prior to procedure. Procedure: ❖ Pt is laying supine on the table. ❖ General I.V sedative is injected. ❖ Contrast media is injected for the venogram. ❖ The catheter passed through the jugular vein to the vena cava. ❖ A TIPS procedure involves creating a pathway through the liver that connects the portal vein to a hepatic vein. ❖ A stent placed inside this pathway keeps it open and allows blood to flow normally from the portal vein through the liver to the hepatic vein, reducing high blood pressure in the portal vein and bleeding from enlarged veins. (a) A needle is passed under radiologic guidance from a hepatic vein into a major portal venous branch, and a guide wire is advanced through this needle. (b) A balloon is passed over the guide wire, creating a tract in the hepatic parenchyma. (c) An expandable stent is placed through this tract. (d) The effective result is a nonselective portosystemic shunt. Type & Amount of C.M #The type is non-ionic contrast media(Omnipaque). # The amount for adult is 40 ml Steps in a TIPS procedure Steps in a TIPS procedure ✓ This technique is preferably done under general anesthesia ✓ After puncture of the jugular vein (most often the right jugular vein) under sonographic guidance, a catheter is introduced into one hepatic vein and wedged in the liver parenchyma. ✓ Gentle injection of dye allows the retrograde visualization of intrahepatic portal vein branches. ✓ CO2 can be used in patients with renal function impairment to avoid dye nephrotoxicity. ✓ The intrahepatic portal vein then is entered with a modified Ross needle. ✓ A guide wire is advanced into the main portal vein. ✓ The tract between the hepatic and the portal vein is dilated with an angioplasty balloon catheter (8– 10 mm) followed by stent placement to maintain the communication between both vessels patent Basic transjugular intrahepatic portosystemic shunt (TIPS) procedure. A curved catheter is placed into the right hepatic vein. A wedged hepatic venogram Image demonstrates advancement of a obtained by using the digital Colapinto needle into the right portal subtraction technique obtained with CO2 gas demonstrates the vein. location of the portal vein. The catheter is wedged in a branch of the right hepatic vein. A TIPS (10 X 68 mm Wallstent dilated with 10 mm X 4 cm balloon) has been placed. Note flow through the Wallstent and filling of the splenorenal shunt  Shunt surveillance:at regular 3 to 6month intervals for Assessment of: MORPHOLOGY Ascites Portosystemic collaterals Size of spleen Diameter of stent (usually 8 to 10 mm) Configuration of stent: areas of narrowing Extension of stent into portal + hepatic veins  HEMODYNAMICS ❑ Direction of flow in: extrahepatic portal vein, R + L portal vein, SMV, splenic vein, all 3 hepatic veins, intrahepatic IVC, paraumbilical vein, coronary vein Peak blood flow velocity within main portal vein Peak blood flow velocity within proximal + mid + distal aspects of stent  Doppler criteria for compromised TIPS function 1.Shunt velocity of 50cm/sec compared with initial post-procedure value 3.Hepatofugal flow in main portal vein  COMPLICATIONS (A) Obstruction to flow Shunt obstruction (38%) Hepatic vein stenosis (B)Trauma (a)Vascular injury Hepatic artery pseudoaneurysm Arterioportal fistula Intrahepatic/subcapsular hematoma Hemoperitoneum (due to penetration of liver capsule)  (b)Biliary injury Transient bile duct dilatation (due to hemobilia) Bile collection (C) Stent dislodgment with embolization to right atrium, pulmonary artery, internal jugular vein. Serious complications, reported in fewer than five percent of cases, may include: 1. Occlusion, or complete blockage, of the stent and rapid recurrence of symptoms 2. Infection of the stent or fabric lining 3. Abdominal bleeding that might require a transfusion 4.Laceration of the hepatic artery, which may result in severe liver injury or bleeding that could require a transfusion or urgent intervention 5.Heart arrhythmias or congestive heart failure. 6. Death (rare). ❖ Follow up with duplex sonography and shunt angiography ❖Early shunt occlusion