Volume 24, Issue 8 , Pages 1134.e9-1134.e13, November 2010
Rupture of a True Giant Aneurysm of the Posterior Tibial Artery: A Huge Size of 6 cm on Diameter
Article Outline
True aneurysms of tibial artery are rare occurrences and their rupture is really rare. We report the case of a 59-year-old man who, after an episode of bacterial endocarditis, presented a posterior tibial aneurysm formation evolved in rupture. To our knowledge, this is the first case of a true giant aneurysm rupture of the posterior tibial artery (diameter, 6 cm). The treatment consisted of aneurysmectomy and surgical arterial ligation. A follow-up of 24 months was performed with good results.
True aneurysms of tibial artery are uncommon and it is really rare rupture. The etiology is unclear: fibromuscular fibrodysplasia, trauma, atherosclerosis, inflammation, infection, and other pathological processes are also probably involved. As all aneurysm, they can evolve to thrombosis and distal embolism more than to rupture. The literature reports only 14 cases of posterior tibial artery and only one case of tibial artery aneurysm rupture.
Case Report
On March 6, 2007, a 59-year-old man presented to our hospital for treatment of bacterial endocarditis (mitral valve vegetations demonstrated on echocardiography). Patient medical history: McArdle's disease, hypertension, dyslipidemia, on October 2006 onset of evening fever regressed without specific treatment (no ematic or lymphatic pathologies neither infectious diseases found with the exception of doubtful positive for Parvovirus), on February diagnosis of spondylodiscitis (diagnosticated by magnetic resonance and confirmed by bone scan and positron emission tomography imaging) and under antibiotic treatment (ceftriaxone and amikacin), on February diagnosis deep vein thrombosis (DVT) of the left lower leg under therapy with low molecular weight heparin (LMWH). During hospitalization he was given appropriate antibiotic therapy, and the patient underwent color flow color duplex ultrasound study (DUS) to check the DVT. The DUS confirmed the presence of DVT of the left lower leg and showed a 28-mm diameter aneurysm of the posterior tibial artery to a length of 25 mm never diagnosed before (Fig. 1). The arterial lumen was patent with little eccentric mural thrombus, the diameter of undiseased proximal and distal posterior tibial artery was regular, and velocity spectral analysis identified distal stenosis and poor flows at level of posterior tibial artery and peroneal artery; the analysis of anterior tibial artery identified no stenosis with regular distal flow. A computed tomography (CT) scan, performed for evaluation of thoracic, abdomen, and legs, confirmed the presence of both spondylodiscitis that left posterior tibial artery aneurysm (diameter, 30 mm; Fig. 2). The patient, few days after the CT scan, developed an intracerebral hemorrhage (presumably due to rupture of cerebral mycotic aneurysm) with consequent coma state associated to right hemiplegia and aphasia, it was necessary to perform a cranial decompression with hematoma evacuation. Therefore, given the clinical condition of the patient (comatose state, hemiplegia, enteral nutrition through a nasogastric tube, breathing through a tracheostomy tube), the left tibial artery aneurysm has become a secondary issue, and it was decided to monitor it over time. Two months after cerebral bleeding, the patient presented clinical and neurological improvement, although his general condition remained critical (percutaneous endoscopic gastrostomy tube placement was thought necessary for nutrition) but the echocardiography control scan revealed no more valvular vegetations. At 8 months after the diagnosis of tibial aneurysm, the patient was referred to our attention for the detection of a sudden swelling of the left calf with pulsating mass associated; the urgent DUS showed a 60-mm diameter aneurysm of the posterior tibial artery ruptured. The patient underwent surgery, through medial approach the giant left tibial posterior aneurysm was detected (Fig. 3) and was found the rupture of the posterior wall of the aneurysm. The patient was successfully treated with aneurysmectomy and surgical arterial ligation under spinal anesthesia. Before, during, and after surgery there was a regular pulse at the dorsal artery of the left foot. Thus, both for regular blood supply of the foot (guaranteed by the anterior tibial artery) and for the suspicion of a mycotic aneurysm, we felt that the treatment by prosthetic graft or by vein graft was inappropriate because of a high risk of superinfection and subsequent prosthetic detachment; hence, we considered the surgical ligation of the posterior tibial artery as an acceptable treatment. The postoperative course was uneventful, the patient underwent intravenous antibiotic therapy for at least 6 weeks. The patient had no ischemic signs in the lower left leg. Histologic examination showed wall aneurysmal dilatation with disappearance of the inner limiting tunic, fibrosis of the medial tunic with atrophy of muscle fibers, elastic fibers fragmentation of external tunic and fibrosis limiting periadventitial tunic and hyaline sclerosis of subintimal plaque; it also showed the absence of inflammatory elements in the material examined. At 24 months follow-up neither foot nor digital ischemia has been observed; the patient has no paresthesias, pain, discomfort, or leg limitation. A 24 months duplex scan follow-up examination revealed good patency of the anterior tibial artery without stenosis, no pseudoaneurysm or recurrent aneurysm of the posterior tibial artery.
Fig. 1
Color duplex sonography showing the aneurysm in the posterior tibial artery (2.8 cm diameter).
Fig. 2
Computed tomography scan showing the posterior tibial artery true aneurysm (3 cm diameter).
Fig. 3
Intraoperative images of tibial artery true aneurysm (6 cm diameter, rupture image).
Discussion
The aneurysms of the infrapopliteal arteries are rare, lots of them appear as false and are associated with trauma or iatrogenic injury.1 True aneurysms of the posterior tibial artery are really rare, only 14 isolated case reports in the literature, and the majority of these were described as either idiopathic or degenerative in origin. The etiology is unclear: traumatic events, collagen matrix alterations, infection, inflammation, fibromuscular dysplasia are more commonly involved than atherosclerosis.2 The mycotic etiology is well documented and reported in literature,3, 4, 5, 6 usually mycotic aneurysms occur most frequently in the intracranial arteries (65%), followed by visceral arteries and vessels of the upper and lower limbs. In our case the patient did not suffer from atherosclerotic disease, vasculitic disorders, or trauma of the leg. Initially, we thought that this unusual aneurysm originated from an embolic vegetation that had settled on the vessel wall and caused erosion and subsequent mural weakness with consequent rupture; moreover, the intracerebral hemorrhage was presumably caused due to the rupture of another mycotic aneurysm, and the histologic examination was negative (no microbiological examination was performed). For diagnosis of tibial aneurysm the color flow duplex ultrasound is usually sufficient (as in our case); with an accurate evaluation of the run-in and the run-off it is possible to proceed with repair, although a study of second level (CT/magnetic resonance or angiography) is better required for aneurysm assessment and its relationship with surrounding structures. Natural evolution of the tibial aneurysms seems to be related to distal embolism and thrombosis, whereas rupture is extremely rare. The indications for treating these lesions are debated in literature,7 some authors assert that aneurysms of any origin must be treated promptly even if they are asymptomatic supported by works that show infrapopliteal aneurysm abruptly rupture with no precursive symptoms8, 9 or show leg ischemia which requires limb amputation.10, 11 In literature we found only one case of ruptured aneurysm of the anterior tibial artery causing acute compartment syndrome,9 but it is also reported that small and asymptomatic aneurysms may be observed safely12 without development of symptoms or enlargement. Generally the treatment indicated are for symptomatic aneurysms, asymptomatic large aneurysms, or those with laminated thrombus.13, 14 The choice of the treatment is debated: surgical (arterial repair, ligation) or endovascular (embolization, percutaneous occlusion with thrombin).15 In literature some authors assert that if the residual infrapopliteal arteries are normal, a simple ligation is permissible,16, 17, 18 others that one functional artery distal to the knee is sufficient for distal blood flow.9, 19 Bypass procedures are complicated by the inherent presence of a septic focus and/or perivascular inflammation: prosthetic grafts should therefore be avoided and autologous vein graft can be used or extra-anatomical bypass through uninfected tissue planes may avoid this. For more extensive infective lesions or for presence of small size vessels or poor run-off vessels the surgical option of ligature, particularly in an emergency setting, may be performed.20 In the case of ligation an alternative to open surgery is given by endovascular embolization or fibrin adhesive injection, generally these techniques are used in the treatment of pseudo-aneurysms rather than true ones and are related to an increased risk of limb ischemia.1, 15, 21 Open repair is the most common management reported in the literature,2, 22 with ligation as a second option. In literature only eight cases of repair of posterior tibial artery aneurysms are reported (Table I): three with saphenous vein bypass,2 two with ligation, two case with unknown treatment, and one with end-to-end direct reconstruction.22 In our case the etiology of aneurysm remained unknown, probably it was mycotic, the cause of rupture was related to rapid improvement of aneurismal sac in few time (grow in 3 cm in 8 month). The authors think that when an aneurysm of tibial artery is detected it must be treated; the surgical repair, if the anatomy is favorable, may be performed (by a direct end-to-end anastomosis or by bypass), when surgical reconstruction is not available, arterial ligation is a good alternative, provided that residual infrapopliteal arteries are normal (as in our case), not causing complications; the role of endovascular and percutaneous procedures has to be assessed.
Table I. Single case reports of posterior tibial arteries aneurysms in the English literature
| Author | Age (yr)/Gender | Treatment | Etiology | Follow-up |
|---|---|---|---|---|
| Pappas et al.23 | UK/UK | UK | UK | UK |
| Katz et al.24 | 37/M | Saphenous vein bypass | Lupus-like syndrome | Polyarthritis onset 3 mo after operation |
| Hasaniya and Katzen9 | 32/F | Ligation | Polyarteritis nodosa | Death in 19th postoperative day |
| Yao and McCarthy12 | 46/M | UK | UK | Good perioperative result |
| Kanaoka and Matsuura2 | 69/F | Saphenous vein bypass | Degenerative | Good perioperative result |
| Jenyo17 | 60/F | Ligation | UK | Good perioperative result |
| Danes et al.25 | UK/UK | Saphenous vein bypass | UK | UK |
| Tshomba et al.22 | 54/M | End-to-end recontruction | Degenerative | Alive and well at 38 mo |
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PII: S0890-5096(10)00143-3
doi:10.1016/j.avsg.2010.01.016
© 2010 Annals of Vascular Surgery Inc. Published by Elsevier Inc All rights reserved.
Volume 24, Issue 8 , Pages 1134.e9-1134.e13, November 2010
