All patients surgically treated for symptomatic PAA in two vascular centers (Vascular Surgery Unit, IRCCS University Hospital Policlinico Sant’Orsola, Bologna, and Vascular Surgery Unit, Cardarelli Hospital, Napoli) from January 2010 to December 2021 were prospectively collected into a dedicated database and retrospectively analyzed. The inclusion criteria were the presence of a symptomatic PAA with acute limb ischemia due to acute thrombosis or distal embolization or with symptoms related to PAA rupture.

Demographic and clinical characteristics of the enrolled patients included the following: sex, age, hypertension (defined as systolic blood pressure ≥ 140 mmHg or diastolic blood pressure ≥ 90 mmHg), dyslipidaemia (defined as total cholesterol level ≥ 200 mg/dL or low density lipoprotein level ≥ 120 mg/dl or specific therapy), diabetes mellitus (pre-diagnosed in therapy with oral hypoglycaemic drugs or insulin), coronary artery disease (CAD, defined as history of angina pectoris, myocardial infarction or coronary revascularization), chronic obstructive pulmonary disease (COPD, defined as chronic bronchitis or emphysema), active smoking, chronic kidney disease (CKD, defined as glomerular filtration rate < 30 ml/min), obesity (defined as a Body Mass Index ≥ 30) and atrial fibrillation. Data about concomitant contralateral PAA and aorto-iliac aneurysm were collected.

Clinical presentation (ischemia or rupture related symptoms and grade of ALI according to Rutherford classification [7]), anatomical features of the aneurysm (diameter, thrombotic involvement, extension) and the number of patent tibial arteries (pTA) were preoperatively evaluated. Thrombolytic intra-arterial therapy was administrated in case of PAA thrombosis/embolization and loss of tibio-pedal runoff arteries, with mild/moderate ALI in the absence of absolute and relative major and/or minor contraindications prior to its initiation. [9]

After physical examination, all patients underwent an urgent lower limbs Computed Tomography Angiography (CTA) to assess the diameter and the extension of the aneurysm and the amount of PAA thrombosis or the presence of rupture signs. The examination was usually extended to aorto-iliac arteries to detect the presence of concomitant aneurysms.

In case of PAA acute thrombosis or distal embolization, a lower limb angiography was performed to evaluate the tibio-pedal arteries run-off. If no outflow vessel was identified at preoperative angiography and the patient’s limb was not immediately threatened (Rutherford IIa ALI [7]), catheter-directed intra-arterial thrombolytic therapy (Urokinase) was delivered to restore blood flow to potential outflow target arteries. Urokinase was administered as a bolus of 100,000 I.U., followed by continuous infusion of 50,000–70,000 I.U./24 h. Concomitant intravenous continuous sodic heparin infusion was associated to maintain an aPTT value two times higher than baseline values. Angiographic evaluations were performed at least every 24 h and thrombolysis was carried out for a maximum of 3 days.

The great saphenous vein (GSV) was also evaluated preoperatively by Duplex Ultrasound (DUS) and was considered suitable if > 3 mm in diameter and without significant wall thickening or intraluminal thrombosis.

The surgical technique was chosen according to the PAA extension, the number of patent tibio-pedal arteries and the GSV suitability. In case of an inadequate GSV an alternative bypass material (ePTFE graft) was employed.

A medial or posterior approach was chosen according to the anatomical features of the aneurysm (extension, involvement of superficial femoral artery) and the surgeon preference.

Surgery was performed under general or spinal anesthesia. All patients underwent broad spectrum antibiotic infusion and systemic heparinization (60–80 IU/kg).

Patients with irreversible limb ischemia with motor and sensory loss of function at presentation (Rutherford III [7]) underwent primary major amputation.

Bypass patency and tibio-pedal runoff were assessed for each patient through clinical and DUS examinations before the discharge. Postoperative mortality was considered at 30 days from the intervention.

In the postoperative period clinical and DUS examination were performed at 1, 3, 6, 12 months and yearly thereafter to evaluate survival, graft patency and limb salvage.

All categorical variables were expressed as frequencies and compared using Fisher’s exact test; continuous variables were expressed with median and interquartile range (IQR) and compared using Mann Withey U. Moreover, late survival and limb salvage rates were evaluated using Kaplan-Maier and compared using log-rank test. Cox proportional hazards model, expressed with hazard ratio (HR) and 95% confidence interval (CI), was used to identify predictors for major amputation.

In all the statistical tests p values (2-tails) of 0.05 or less were considered statistically significant. The statistical analysis was performed using SPSS 23.0 for Apple (SPSS Inc, Chicago, Illinois, USA).