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Seminar on basic principles of endovascular surgery
- 1. SEMINAR ON BASICPRINCIPLES OF ENDOVASCULAR SURGERY PRESENTER : Dr. BISWAJIT DEKA PGT, DEPTT. OF SURGERY SILCHAR MEDICAL COLLEGE
- 2. INTRODUCTION • Endovascular surgeryis an intra-arterial method that uses catheter guided devices to assist restoration of blood flow in an occluded vessel. • This is accomplished either by providing a thrombolytic agent directly to the clot or removing the clot mechanically from the site of vessel occlusion or both.
- 3. HISTORICAL IMPORTANCE • IvanSeldinger, a swedish radiologist ,was the 1st physician to describe a unique method of establishing arterial access using a guidewire technique in 1953, which heralded an evolution from diagnostic to therapeutic angiography. • A decade later, Fogarty detailed the use of a balloon-tipped catheter to extract thrombus.
- 4. • Dotter &Judkin in 1964 described a method of dilating an arterial occlusion using a rigid Teflon catheter to improve arterial circulation. • In the field of venous intervention, catheter based vena caval filters were introduced by Greenfield in 1973 and have revolutionized the current approach in the prevention of pulmonary embolism.
- 5. • The techniqueof balloon angioplasty was introduced by Gruntzig,who performed the 1st coronary artery intervention in 1974. . 1st intravascular balloon expandable stent was developed by Palmaz et al in 1985. • Several years later, Parodi,an Argentinean vascular surgeon, combined both a Dacron graft & balloon expandable stent technology to creat a stent graft, which was successfully used to exclude an abdominal aortic aneurysm.
- 6. Headings • Needles • Access •Guidewires • Hemostatic sheath • Catheter • Angioplasty balloons • Stents • Stent grafts
- 7. NEEDLES • Used toachieve percutaneous vascular access. • Size – dictated by diameter of guidewire • Most often 18G needle used – accept a 0.035 inch guidewire.
- 8. • 21G micropunctureneedle- accept a 0.018 inch guidewire. • Seldinger needle- most popular , used for single & double wall puncture techniques.
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- 10. ACCESS • Femoral arterialpuncture – most common site • Common femoral artery(CFA)- punctured over medial third of femoral head , landmarked using fluoroscopy. • Retrograde femoral access - most common – Size & fixed position of common femoral artery – Ease of compression against the femoral head
- 11. • Single wallpuncture technique → needle with sharp beveled tip & no central stylet → anterior wall of vessel punctured → intraluminal position indicated by pulsatile back bleeding → useful for : graft puncture abnormal clotting profile if thrombolytic therapy needed
- 12. • Double wallpuncture technique –Blunt needle with removable inner cannula –Puncture both walls of artery –Withdrawn until bleeding is obtained to confirm intraluminal position prior to advancing a guidewire –Disadvantage: bleeding from posterior wall.
- 13. • Avoid puncturingexternal iliac artery - Retroperitoneal hemorrhage • Puncturing low,at/below CFA bifurcation –Thrombosis –Pseudo-aneurysm of superficial femoral or profunda femoris artery .
- 14. GUIDEWIRE • Used tointroduce, positon & exchange catheters • Has a flexible & stiff end • Flexible end- placed in the vessel • Composed of a stiff inner core & an outer tightly coiled spring that allows a catheter to track over the guidewire
- 15. • 5 Essentialcharacteristics of guidewires –Size –length –Stiffness –Coating –Tip configuration
- 16. Size: –Max transverse diameter:0.011 to 0.038 inches –Most aortoiliac procedure: 0.035 inch used –Smaller diameter 0.018inch: small vessel angiography (infrageniculate / carotid) Length: –180 to 260 cm –Increased length: difficult to handle : risk of contamination
- 17. • While performinga procedure,it is important to maintain the guidewire across the lesion until the completion-arteriogram has been satisfactorily completed. Stiffness – Stiff wires allow for passage of large aortic stent graft devices without kinking. – Usefull while performing sheath or catheter exchanges around a tortuous artery. – Eg: Amplatz wire
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- 19. Coating Hydrophilic coated guidewire,like Glidewire -useful for difficult catheterization –Coating is primed by bathing the guidewire in saline solution. –The slippery nature of this guidewire along with its torque capability facilitate in difficult catheterizatons.
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- 21. Tip configuration –Angled tipwires like angled Glidewire can be steered to manipulate a catheter across a tight stenosis or to select a specific br. of a vessel –The Rosen wire has a soft curled end- makes it ideal for renal artery stenting • Its soft curl prevents it from perforating small renal branch vessels
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- 23. Hemostatic Sheaths • Devicethrough which endovascular procedures are performed. • Protect the vessel from injury as wires & catheters are introduced. • One way valve: prevents bleeding. • Side-port: to administer heparin / contrast. • Commonly used for percutaneous access have a 5 to 9F inner diameter.
- 25. Catheter • A widevariety of catheter exist that differ primarily in the configuration of the tip. • Multiple shapes permit access to vessels of varying dimensions and angulations. • Used to perform angiography & protect the passage of balloons and stents • Used to direct the guidewire through tight stenoses or tortuous vessels.
- 26. Angioplasty Balloons • Differprimarily in their length, diameter & the length of the catheter shaft. • With advanced technology – lower profiles have been manufactured(i.e.,the size that the balloon assumes upon deflation) • Used to : perform angioplasty on vascular stenoses : deploy stents : assist with additional expansion after insertion of self expanding stents
- 28. • Noncomplaint &low-compliance balloons tend to be inflated to their present diameter & offer greater dilating force at the site of stenosis. • Low-compliance balloons: mainstay for peripheral intervention. • Under fluoroscopic guidance, balloon inflation is performed until the waist of the atherosclerotic lesion disappears & the balloon is at the full profile. • Trackability, pushability, and crossability of a balloon should be considered when choosing a particular balloon.
- 29. • Shoulder length:important factor to consider when choosing a balloon because of the potential to cause injury during performance of PTA(percutaneous transluminal angioplasty) in adjacent arterial segment. • There is always risk of causing dissection or rupture during PTA, thus a completion angiogram is performed while the wire is still in place. • Leaving the wire in place provides access for repeating the procedure,placing a stent or stent graft if warranted.
- 30. Stents • Used afteran inadequate angioplasty with dissection or elastic recoil of an arterial stenosis. • Serve to buttress collapsible vessels & help prevent atherosclerotic restenosis. • Manufactured from: stainless steel tantalum cobalt based alloy nitinol →Classified into self expanding & balloon expandable stents
- 31. Self expanding stents •Deployed by retracing a restraining sheath • Come in longer length than balloon expandable stents. • Used to treat long & tortuous lesion • Ability to continually expand after delivery allows them to accomodate adjacent vessels of different size. • Ideal for internal carotid artery
- 32. • Oversized by1 to 2mm relative to the largest diameter of normal vessel adjacent to the lesion – to prevent immediate migration. • Consist of : Elgiloy (cobalt+chromium+nickel ) Nitinol (nickel + titanium)
- 33. Balloon expandable stents •Stainless steel • Mounted on angioplasty balloon • Deployed by balloon inflation • Shorten in length during deployment,which depends on stent geometry & diameter to which balloon is expanded. • More rigid & limited flexibility • Ideal for short segment/ostial lesions.
- 34. Drug eluting stents •Recent development • Nitinol with anti-inflammatory drugs • Prevent restenosis • Beneficial in coronary arterial lesion, peripheral arterial disease.
- 39. Stent grafts Initiated byParodi in 1991 • Metal stent covered with fabric • Used in traumatic vascular lesion--arterial disruption, AV fistulas. • Eg : – AneuRx device – Gore excluder device – Endologix powerlink device – Zenith device – Talent device – Endurant device
- 40. • Patients withinfrarenal aneurysm with atleast 15mm proximal aortic neck below renal arteries & not greater than 60 degree of angulation. Newer generation endograft: more flexible stents & lower profile delivery system –AFX Endovascular AAA system –Aorfix flexible stent –Ovation prime stent
- 41. Complication • Periprocedural hemorrhage--mostcommon • Access site hematoma, GI hemorrhage • Retroperitoneal hemorrhage • Cardiac- arrhythmia,hypotension. • Contrast related- allergy , ARF • Perforation, dissection • Embolization • pseudoaneurysm
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