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ENDOVASCULAR SURGERY - PAST, PRESENT AND FUTURE

Ramakrishna Pinjala
Head of the Department of Vascular Surgery, Nizamís Institute of Medical Sciences, Tutor for the Royal College of Surgeons, Edinburgh.

Management of vascular problems has taken many twists and turns as we are understanding the vascular biology, coagulation and immunology which maintains the integrity of the vessel wall and blood flows. Many technical skills were acquired and mastered by the vascular surgeons during the past few decades to repair or reconstruct the blood vessels with autogenous vein grafts and synthetic grafts. But, the revolution took place in 1964, when Charles Dotter first performed percutaneous dilatation of the superficial femoral artery in midst of skepticism and succeeded in healing the ischaemic leg. This minimally invasive technique has attracted many throughout the world and soon modifications for the Dotter technique were introduced to treat vascular stenosis and occlusion. Then Gruntzig introduced catheters with balloons at the distal end for dilatation of the stenotic segments. An array of new devices were introduced for treating the vascular lesions percutnaeously and expanded the science and art of endovascular therapies for vascular problems. A new sub specialty was born embracing all this progress and the surgeons, radiologists and cardiologists retained themselves to face these new challenges in providing endovascular therapies in their fields. Now, it is possible to treat the vascular lesions such as stenosis, occlusion, A-V fistulous communications, aneurysms, malformations and haemorrhage with these endovascular procedures.

Percutaneous endovascular procedures need a good vascular access to place vascular sheath through which different types of guide wires, catheters, stents, stent grafts, embolic material, suction devices, IVUS and angioscope can be easily negotiated. Femoral artery in the groin is usually used for arterial puncture and placement of a sheath depending on the site and side of the lesion, (Fig. 1) which needs to be treated. Single wall puncture of the femoral artery is preferable to double wall puncture for avoiding the complications if thrombolytic therapies are to be given. One can puncture the artery to place the sheath when femoral artery is not palpable based on the anatomical points. Doppler probe can be used as a guide to puncture femoral artery in such situations. Femoral artery puncture may be difficult in obese and women with small diseased and calcified vessels. Rarely a small (one-inch) incision and careful dissection and isolation of the artery can be helpful to place sheath in the femoral artery especially when the antegrade punctures are needed to treat popliteal and tibial artery lesions. Once a guidewire is passed through the sheath it is manoeuvred through the stenotic or occluded segment using different techniques (Figs. 2,3). This is considered as the crucial part of the endovascular procedures. Different types of guide wires are available to facilitate easy navigation through the tortuous, ragged, ulcerated and diseased vessels. The tips of these wires are usually soft and flexible to avoid injury to the vessel wall. Guide wires can pierce the vessel wall and precipitate the dissection. Some of these wires are coated with hydrophilic material so that they can glide through the narrow vessels. The shaft of the guide wire has to be stiff or extra stiff if a stent or balloon has to be negotiated over it to reach the lesions across acute angles (branching). Selection of a proper sheath and guide wire is essential for a successful percutaneous endovascular procedure.

Fig 1
Fig 1. Left iliac angiogram showing long segment stenotic disease involving the bifurcation of the common iliac artery and ostium of the internal iliac artery


Fig 2
Fig 2 : Deployment of a long stent in the iliac artery and small stent at the ostium of the internal iliac artery for reconstruction of the bifurcation


Fig 3
Fig 3 : Completion angiogram showing patent common iliac aretery, external iliac artery and internal iliac artery.


PERCUTANEOUS ENDOVASCULAR THERAPIES FOR THE EXTREMITIES

Aorto-iliac bypass operation is one of the most commonly performed operations by the vascular surgeon and it gives excellent results. Introduction of percutaneous procedures has certainly changed the scenario in the last 5-10 years in all the major hospitals with angiographic facilities. The long-term (5 year) results of aortic angioplasty and common iliac angioplasty are good and comparable to the surgical results. In early periods the angioplasty was confined to short stenotic segments, but with the introduction of stents it has become possible to open even long segment occlusions with high resistance. In aorto-iliac junction lesions two balloons are placed one from each femoral artery and inflated simulatenously to dilate the lesion. This technique is known as "kissing balloon technique". This technique is commonly used for dilating lesions at the vascular branching. If there is lot of old and fresh thrombus some prefer to consider intra arterial thrombolytic therapies for 24 hours to dissolve the thrombi prior to balloon angioplasty and stenting. It would be helpful to prevent distal embolization of the thrombi during the balloon angioplasty. Role of primary stenting in aortic and iliac region in all cases is not accepted by many as it may turn out to be too expensive and unwanted in all cases. Stents are preferred in selected group of patients with dissection or recoiling after angioplasty impeding flows. Rigid, balloon expandable stents and flexible self expanding stents have shown to be effective in correcting the post angioplasty dissection and recoiling of the diseased segments. However, in India primary stenting is considered as too expensive and one would hesitate to consider it whenthere is no great difference in outcomes between primary stenting and selective stenting. The results of endovascular therapies are found to be best in common iliac artery lesions but as we go down the arterial tree up to foot, the results (5 year patency rates) would be falling from 80% to 20% at the tibial arteries. Endovascular therapies for common femoral artery lesions may be more expensive than operative therapies. One would always hesitate to place a stent in the groin as it may be compressed during sitting or squatting. Femoro-popliteal remote endarterectomy through a small incision in the groin and endograft placement was considered as another of treatment for the long segment (40 cm) occlusion of the femoro-popliteal artery. Sub intimal angioplasty of the long segments of superficial femoral artery has given good results in some centres. But if there is excessive calcification in the vessel wall then, it may not be possible to dissect out a sub initimal plane in them. The long-term (5 yrs) results of femoro-popliteal angioplasty are inferior to the iliac artery angioplasty. The new plaque debulking devices such as rotablator (atherectomy device), Laser are too expensive to use and that means the cost of the procedure is going to be prohibitively high. In addition one may require burs of different size to debulk the lesions to get a decent lumen and that has to be supplemented with angioplasty and stent. In totally occluded segments a pilot channel can be made with a single bur which is adequate for the free passage of the guide wire and balloon catheter. Later one can consider primary stenting of that area to get the best results. Cutting balloons are used for dilating the tight lesions in the renal, popliteal and tibial arteries.

Endovascular therapies are extended to treat the abdominal aortic aneurysm with modular prosthesis (2-piece or 3-pieces). Spiral CT angiograms can accurately measure the vessel diameters (anterior and posterior) where the stents are to be deployed. One can select or order prosthesis based on these measurements. If there is a mismatch between the vascular diameters and stent graft diameter it would result in "endoleak" in to the aneurysmal sac. The aneurysmal sac pressures may actually increase and precipitate early rupture of the aneurysm due to the endoleak. In some centres with facilities and expertise it is now possible to consider the endovascular repair of the infra renal abdominal aortic aneurysm as an out patient procedure. Usually patients are kept under observation after the endovascular procedures, due to fear of bleeding from the puncture sites, as they are allowed to seal with internal haemostatic mechanisms. Now percutaneous sealing devices are available to close the puncture sites effectively. This type of device is more useful in patients who have received thrombolytic agents or group IIb IIIa antibodies to prevent the thrombosis. Iliac artery aneurysms can also be treated by placement of an endo graft. If the aneurysm is at the bifurcation of the common iliac artery, it would be necessary to block internal iliac artery before placing endovascular stent graft from common iliac artery to external iliac artery. If the internal iliac artery is not excluded then the aneurysm would continue to enlarge and rupture due to the persistent blood flows.

The percutaneous endovascular procedures are relatively less invasive and considered to be safer even in those patients who are otherwise considered high risk patients for surgical treatments. However, there are complications associated with these procedures. The complications can occur at puncture site, angioplasty site or distally. The puncture site can bleed or there can be large haematoma formation due to leak in to the subcutaneous tissues. It may develop in to a pseudo aneurysm. If the angioplasty balloon does not match with the size of the vessel, then there is a chance for the rupture of vesesel. Stents are known to migrate and they can be accidentally misplaced due to miscalculation. Rarely stents can get infected and mycotic aneurysms can be produced. Acute thrombosis of the angioplasty sitemay necessitate the use of thrombolytic therapy or clot suction devices to retrieve the embolic material. Neo-Intimal hyperplasia after angioplasty or in stent stenosis is considered as a major problem in small vessels. This occurs in femoral and popliteal arteries more often than in the iliac arteries. Different types of vascular brachytherapy techniques are tested to find out the efficacy. This may look cumbersome at this time to organize the cath lab with all these gadgets which are going to increase the cost of the procedure beyond expectation.

What could be the future for endovascular therapies? The social and economic factors are going to control the future of the endovascular therapies in India. Plaque debulking devices such as Laser, atherectomy devices failed to get satisfactory long-term benefits. Endovascular therapy is going to be one of the most common forms of treatment for the aortoiliac and iliac artery lesions. The endovascular delivery of the gene therapies may take new twist and probably neovasculogenesis may be possible in the coming years with better understanding of vascular molecular biology. While the surgical therapies continue to play a major role in management of acute vascular trauma lesions, Endo vascular therapies may take a leap in the management of all chronic and acute lesions as the first line of management. In the coming years the academic institutions will be soon introducing the endovascular courses in their academic programmes to provide adequate training for all those interested in vascular interventions and surgery.

REFERENCES

1.Dotter CT, Judkins MP. Transluminal treatment of arteriosclerosis obstruction. Description of a new technique and a preliminary report of its application. Circulation 1967; 30 : 654.

2.Gruntzig A, Hopff H. Perkutane Rekanalization Chronischer arteriller verschulusse mit einem neuen Dilatations - katheter. DtschMed Wochenschr 1974; 99 : 2502.

3.Palmaz J, Laborde J, Rivera F, et al. Stenting of the iliac arteries with the palmaz stent : experience from a multicenter trial. Cardiovasc Intervent Radiol 1992; 15 : 291.

4.Dake MD, Semba CP, Enstrom RJ, et al. Percutaneous treatment of Venous occlusive disease with stents. J Vasc Interv Radiol 1993; 4 (1) : 42.

5.Simpson JB, Zimmerman JJ, Selmon RM, et al. Transluminal atherectomy : Initial clinical results in 27 patients. Circulation 1986; 74 (suppl. II) : II-203.

6.Whatling PJ, Gibson M, Torrie EPH, et al. Iliac occlusions : Stenting or crossover grafting? An examination of patency and cost. Eur J Vasc Endovasc Surg 2000; 20 : 36-40.

7.Sullivan TM, Childs MB, Bacharach JM, et al. Percutaneous transluminal angioplasty and primary stenting of the iliac arteries in 288 patients. J Vasc Surg 1998; 28 : 94-101.

8.Tetteroo E, Van der Graff Y, Bosch JL, et al. Randomized comparison of primary stent placement versus primary angioplasty followed by selective stent placement in patients with iliac artery occlusive disease. Dutch iliac stent trial study. Lancet 1998; 351 : 1153-59.

9.Broeders IA, Balkensteijn JD, Olree M, et al. Preoperative sizing of grafts for transfemoral endovascular aneurysms management : a prospective comparative study of spiral CT angiography, arteriography and conventional CT imaging. J Endovasc Surg 1997; 4 : 252-61.



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