Australia & New Zealand Society of Vascular Surgeons » 2003

Femoro-distal anterior tibial vein bypass graft entrapment: a case report

cmsadmin@go4.com.au — Wed, 26 Aug 2009 00:39:19 +0000

The phenomenon of entrapment of the femoro-popliteal vein bypass graft has been preveously reported. However, to the authors’ knowledge, there has been no report of femoro-distal anterior tibial vein graft entrapment. This poster describes a case of femoro-distal anterior tibial vein bypass graft entrapment demonstrated by duplex ultrasound scan. A 78 year old man with a femoro-distal anterior tibial vein bypass graft was referred to the Vascular Laboratory of the Austin Hospital for routine graft duplex ultrasound surveillance scan. An in-situ long saphenous vein was used as the graft conduit. The vein graft was anastomosed to the common femoral artery in the groin, travelled subcutaneously in the medial aspect of the thigh and calf, crossed subcutaneously over the tibia a few centimetres above the ankle and was anastomosed to the distal anterior tibial artery at the level of ankle. Graft duplex scan demonstrated normal range of peak systolic velocities throughout the vein graft when the limb was examined in supine neutral position. However, during active dorsiflexion, an increased peak systolic velocity (>450 cm/sec) was detected in the distal graft at the point where the graft crossed over the tibia. Our explanation of this phenomenon is that during active dorsiflexion, the tendon of the tibialis anterior muscle moves anteriorly compressing the vein graft against the skin. This report demonstrates that entrapment may occur in a vein bypass graft to the distal anterior tibial artery or dorsalis pedis artery. Clinicians who examine such grafts should be aware of this condition. Furthermore, modification of surgical technique for femoro-distal anterior tibial or dorsalis pedis vein bypass graft to avoid the graft crossing over the tibia may reduce the occurrence of graft entrapment.

Irradiated vein grafts for prevention of vein graft stenosis

cmsadmin@go4.com.au — Wed, 26 Aug 2009 00:38:44 +0000

Introduction Vein graft stenosis is believed to be entirely due to intimal hyperplasia. Approximately 10-30% of infrainguinal bypass vein grafts fail within 2 years requiring further intervention. Ionizing radiation has been used with some success to reduce coronary re-stenosis rate after angioplasty. The aetiology of restenosis in the post-angioplasty vessels is thought to be due to intimal hyperplasia and vascular remodeling from the injury sustained to the arterial wall during angioplasty. We postulated that irradiating the vein graft immediately prior to implantation as a bypass graft should inhibit proliferation of smooth muscle cells and prevent the development of graft stenosis. Methods Thirteen patients were involved in a pilot study where vein grafts were harvested and irradiated with 10 Gy ionizing radiation and then implanted. A variety of parameters were measured including early duplex Doppler ultrasound assessing patency. Results All grafts had very good early patency rates. Eight of 12 (66.7%) grafts failed suddenly with no warning after 6 months. The study was suspended hereafter pending review. Conclusions Our study suggests that ionizing radiation may be able to prevent intimal hyperplasia but may have a detrimental effect on the long-term outcome. This study raises significant concerns about using ionizing radiation to reduce intimal hyperplasia in vein bypass grafts.

The endovascular repair of thoracic aortic lesions: short term analysis of 76 cases

cmsadmin@go4.com.au — Wed, 26 Aug 2009 00:38:09 +0000

Aim The safety, efficacy and feasibility for the endovascular repair of thoracic aortic aneurysm and dissections were retrospectively analysed. Method From Aug 1998 to Aug 2003, 14 cases with true thoracic aortic aneurysm and pseudoaneurysm (Group 1) and 62 cases with thoracic aortic dissection (Group 2) were treated by endovascular devices. CTA or MRA were used to obtain the morphology of the lesions and the diameter and length of the proximal landing zone. The stent graft was deployed at the proximal neck of the aneurysm or first tear entry in aortic dissection through the iliac or femoral artery under fluoroscopic control. The stent grafts used were Vanguard (n=1), Talent (n=65) and domestic stent grafts (n=10). Results In Group 1, 10 aneurysms located between T5-T8, 2 aneurysms located between T8-T12 and 2 thoracic abdominal aortic aneurysms (TAAA) were treated. 2 left subclavian artery (LSA) bypasses were performed because of short proximal neck and poor right vertebral artery blood supply. Another case had endovascular repair associated with open surgery. All of the stent grafts were placed correctly. One patient died from myocardic infarction 7 days after the endovascular procedure. 2 cases had type I endoleak. There were no paraplegic complications. In Group 2, there were 51 chronic and 11 acute dissections. 56 patients had Stanford B dissection and 6 patients with first tear entry at aortic isthmus but retrograde to ascending thoracic aorta (Stanford A). The first tear entry position was 52 located at isthmus of thoracic aorta and 10 located between T8-L1. There was only one entry in 2 cases and more than 2 entries in 46 cases. There were variable patterns of visceral and renal artery problems which will be described. In Group 2, all of the procedures were a technical success. One patient with acute dissection died because of a new retrograded dissection and cardiac tamponade one day after the procedure. Intentional stent graft coverage of the subclavian artery without bypass was performed in 16 selected cases. The average pressure of the left brachial artery was 56 mmHg after deployment. 4 patients complained of post-interventional exercise-dependent paraesthesia without difference between the upper extremities strength. The endoleak rate was 19.2%. There were no surgical conversions, paraplegia and end organ or limb ischaemia complication in this group within 30 days after the procedure. There was improved visceral and renal artery perfusion in 89%: 11% were unchanged. Conclusions The endovascular technique is a safe, efficient and feasible method to repair thoracic aortic lesions. There still remains an appreciable endoleak rate which requires addressing. Covering the LSA is safe in selected patients. The false channel mainly affects renal arteries; SMA is rare. There are many different patterns of damage to visceral arteries. Endovascular repair technique improves the blood supply of the true channel in most cases. Key Words: aorta, aneurysm, dissection, endovascular.

A prospective study of systemic inflammatory syndrome in patients following endoluminal aortic aneurysm repair

cmsadmin@go4.com.au — Wed, 26 Aug 2009 00:37:21 +0000

Introduction Fever is common after endoluminal abdominal aortic aneurysm (eAAA) repair, and may be part of a specific ‘post-implantation’ syndrome. The mechanism remains obscure, but there is a resemblance to the Systemic Inflammatory Response Syndrome (SIRS) which occurs after other physiological insults. We performed a prospective pilot study to investigate the correlation of clinical and procedural parameters with the incidence of SIRS in patients following eAAA. Methods We prospectively collected data regarding patient demographics, vascular anatomy, procedure details and clinical course, with particular study of inflammatory and thrombotic markers collected pre-operatively and during the post-operative period. A routine septic screen consisting of chest X-ray, urinalysis, urine culture and blood cultures was used to investigate any evidence of septic aetiology. Results Eighteen (18) consecutive patients were enrolled in the pilot study. Four patients were excluded due to steroid medication (n=3) or post-operative bacteremia associated with pneumonia (n=1). Of the remaining 14, typical SIRS developed in 7 patients (50%), while 5 patients had fever less than 38oC (35.7%). Only 2 patients remained afebrile (14.3%). The following factors did not effect incidence of SIRS: AAA size, patient age, procedural time, aortic ballooning, contrast volume and use of anti-platelet agents had no significant effect. Patients who developed SIRS had significantly more development of new thrombus (diameter % or cross-sectional area%) within the AAA sac (p<0.05). Conclusions This study supports the existence of an endovascular Systemic Inflammatory Response Syndrome (‘eSIRS’) which occurred in 50% of patients. There is preliminary evidence of an association with large amount of fresh thrombus within the sac. Further studies including more precise volume measurements and parameters of thrombosis are warranted.

Medical indemnity issues

cmsadmin@go4.com.au — Wed, 26 Aug 2009 00:36:43 +0000

The Medical Indemnity (Prudential Supervision and Product Standards) Act 2003 was passed in March 2003 and introduced July 1, 2003. The objects of the Act are; “(a) to ensure that health care professionals have access to medical indemnity cover that is provided by properly regulated insurers; and (b) to specify minimum standards for medical indemnity cover that is provided to health care professionals.” The Act prohibits the provision of medical indemnity directly to health care professionals other than via individual contracts of insurance. Australian medical indemnity had for more than 100 years, until the introduction of the Act, been provided mainly through membership of discretionary, not-for-profit, medical defence organisations (MDOs), as it still is in most Commonwealth countries. Other associated legislation, both Federal and States have further distorted the previous indemnity model. The introduction of various legislation has had many anticipated and some unanticipated consequences. Since the introduction of the Act, all Australian MDOs and their members (with the exception of United Medical Protection) have been affected. The responses of stakeholders have been indicated by written and other communications both in the public arena and at an MDO-member level. Those communications have indicated a great deal of anxiety and confusion amongst medical practitioners, which has translated to changes in their behaviour. Those changes include risk avoidance behaviour that has had, and will continue to have, significant flow-on effects on the range, type and location of medical services, and the cost and availability of those services.

Subintimal angioplasty in the management of claudication and critical ischaemia

cmsadmin@go4.com.au — Wed, 26 Aug 2009 00:36:00 +0000

A review of 60 cases of SFA subintimal angioplasty in the management of claudication and SFA or distal subintimal angioplasty in the management of critical ischemia. Participating vascular surgeons and interventional radiologists. Follow up of cases with clinical examination, ABI and duplex U/S. Analysis of technical success rates, complications and early/intermediate results. Both studies are in evolution and recruiting.

Is endograft the preferred modality of treatment in AAA – 80 year old

cmsadmin@go4.com.au — Wed, 26 Aug 2009 00:35:26 +0000

Operative treatment for abdominal aortic aneurysm (AAA) in octogenarians has traditionally been met with guarded enthusiasm. While robust octogenarians have been recognized to recover from conventional open AAA repair, most experienced vascular surgeons recognize that it is uncommon for an octogenarian to undergo such an operation and have full recovery back to baseline status. Recent technology of endovascular AAA repair (EVAR) has resulted in new enthusiasm in the management of AAA in the elderly. Since EVAR technology has been embraced and widely applied to patients with AAA, many reports have documented technical success of EVAR implants, their intermediate-term durability, and their complications. Little attention has been given to refine our knowledge of AAA and the benefit (or lack of benefit) patients receive from AAA repair. Questions regarding risks of rupture and rate of growth remain. Available data regarding risk of rupture are antiquated and difficult to apply to specific populations of AAA patients. Marginal, if any benefit from AAA repair has been demonstrated in both the UK small aneurysm trial and US veterans studies. Without clear benefit from AAA repair in the elderly, widespread repair of AAA with EVAR in this population may not be justified. Furthermore, costs of adding repair to a population previously felt unsuitable is substantial. While EVAR is likely the preferred method of AAA repair in the elderly, there is no basis for expanding indications for AAA repair with EVAR to a large group of octogenarians.

Fate of the ancure graft – what does it mean for endovascular AAA repair?

cmsadmin@go4.com.au — Wed, 26 Aug 2009 00:34:39 +0000

The Ancure endovascular graft (Guidant, Menlo Park, CA) entered the US market in 1999 with a pre-marketing agreement (PMA) including a responsibility on the part of the vendor to teach surgeons-interventionalists appropriate deployment techniques and track performance/complications. As experience grew, ‘bail-out’ maneuvers not described in the pre-market trials and not included in the original PMA were identified to aid in graft deployment. The vendor failed to submit PMA supplement to take into account these ‘bail-out’ maneuvers and failed to report implantation complications. These events became apparent in March of 2001 and, as a result, Guidant suspended manufacture and withdrew the Ancure graft from the US market. A new multi center trial was undertaken to study evolving ‘bail-out’ techniques of Ancure graft and the graft returned to the US market in September 2001. Data from the 2001 study was favorable in terms of AAA exclusion and success of the newer ‘bail-out’ techniques yet Ancure market share never recovered. By mid-2003, the Department of Justice filed criminal charges against the corporation. Heavy fines combined with lack of market share and absence of profitability forced Guidant to exit the AAA market. The causes of Ancure’s failure include problems with ease of use, corporate regulatory irregularities, manufacturing complexity, expense, and failure of profitability. The durability of the Ancure graft is arguably excellent compared to other grafts available in the US yet it is the first to exit the market. Qualities beyond durability are necessary for success of an endovascular AAA graft in the US market.

US experience and the Excluder

cmsadmin@go4.com.au — Wed, 26 Aug 2009 00:34:02 +0000

The Pivotal Trial leading to FDA approval of the Excluder in the United States was undertaken in 19 clinical centers. Study design was a multi center prospective concurrent control design similar to other endograft trials performed in the US. The enrollment dates were from late 1998 until early 2000. Two hundred thirty-five patients were treated with high rate of technical success and few major operative events. Follow-up is complete in more than 90% of available patients at three years. Cumulative major adverse events were significantly lower in the Excluder cohort of patients (p < .0001). Similarly, freedom from first major adverse event significantly favored the Excluder patients. There was no demonstrable survival benefit over conventional repair. At three years, 87% of patients are free of any endoleak, 9% have Type II leaks, and 4% have indeterminant type leaks. Twenty-two percent of patients have decreased aneurysm size, 54% have no change in aneurysm size, and 24% have increase (> 5 mm) in aneurysm size. Late conversions have occurred in a total of five patients for an overall rate of less than 2% with no reports of aneurysm rupture. Compared to conventional open repair, the Excluder at three years follow-up continues to have lower rates of major adverse events, a high rate of aneurysm exclusion, absence of aneurysm rupture, and low late conversion rate. The etiology of aneurysm enlargement in the absence of endoleak and its clinical significance has not yet been defined.

The value of stump pressure as an indicator for shunting during carotid endarterectomy

cmsadmin@go4.com.au — Wed, 26 Aug 2009 00:33:29 +0000

Stump pressure measurements have been used to select patients for bypass shunting during carotid endarterectomy. Based on the assumption that low ICA back flow reflects inadequate cerebral perfusion, ‘acceptable’ stump pressures are empiric and have not been validated against clinically assessed neurological function. The performance of carotid surgery under local anaesthetic provides an opportunity to relate stump pressure to cognitive function. The practice of carotid endarterectomy in Victoria’s largest rural centre, over a four year period, was assessed retrospectively. Most cases were performed by one of two vascular surgeons. Local anaesthetic was the preferred approach of one operator whose shunt rate was compared to that of the second surgeon who had a policy of selective shunting based on stump pressures. 317 carotid endarterectomies performed between March 1999 and March 2003 were available for the purpose of comparison. 206 were conducted under local anaesthetic with a shunt rate of 7.8%. Among 111 cases where selective shunting was applied under general anaesthetic the rate was 54%. Patient demographics of the two groups were comparable and there was no appreciable difference in patch rate, operation time or postoperative length of stay. Stroke and death rates for the two groups were within an acceptable range. The large disparity between shunt rates of the two groups placed the level at which ICA back pressure is deemed ‘acceptable’ in question. It has prompted the conduct of a prospective study of stump pressure measures and cognitive function with carotid cross-clamping under local anaesthetic.