Assessment of Bypass Surgery and Balloon Angioplasty Effects in Peripheral Arterial Disease Using Contrast Ultrasound

Contrast ultrasound perfusion imaging (CUPI) is a novel tool for the assessment of muscle perfusion deficits in peripheral arterial disease (PAD). In this study we want to examine the effect of bypass surgery and balloon angioplasty on the calf muscle blood supply. We hope find a new way of quantifying success or failure of invasive treatment strategies.

Contrast ultrasound perfusion imaging (CUPI) was developed at the University Hospital of Freiburg, Germany in 2005 for the assessment of skeletal muscle perfusion deficits in peripheral arterial disease (PAD). It has been reported previously by the investigators that the contrast agent wash-in is significantly prolonged in PAD with respect to the extent of disease and with respect to the degree of collateralization.

The goal of this study is to examine the effect of revascularization procedures on muscular perfusion in 15 PAD patients undergoing lower limb artery bypass surgery and 15 PAD patients undergoing percutaneous angioplasty (PTA) before and after intervention. Based on the data from a pilot study, a power calculation for an alpha = 5% with a power of 80% and an assumed standard deviation of 10 s yielded a necessary patient number of 29 per group to detect a decrease in wash-in time of 7.5 s. In this intra-individual comparison we aim to compare 30 patients pre with the same 30 patients post revascularization.

We hypothesize 1) that the contrast agent wash-in in the target muscle will significantly improve after revascularization and 2) that standard non-invasive tests such ankle-brachial index (ABI) will not correlate with the CUPI findings. The results of this trial will help to further understand the diagnostic accuracy of CUPI in quantifying limb muscle perfusion deficits.

Patients with symptomatic PAD and an indication for revascularization will undergo CUPI less than 8 weeks prior and less than 3 weeks after the revascularization procedure. A second follow-up CUPI examination is performed 3 - 6 months after the revascularization procedure.

Eligibility Criteria:
Inclusion Criteria:

* male or females \> 18 years old
* PAD Fontaine stages IIb, III or IV
* conventional angiography or magnetic resonance angiography
* a severe lesion (≥80% stenosis with a peak velocity ratio intrastenotic / prestenotic ≥4.0 in Duplex ultrasound or occlusion) has to be present in the common or external iliac, common or superficial femoral, popliteal or one or more infrapopliteal arteries, which is accessible to revascularization
* indication for revascularization, i.e. lower limb artery bypass surgery or PTA (based on the treating physician's decision)
* revascularization appointed within the next 6 weeks of study inclusion
* patients, who have the ability to understand the requirements of the study, provide written informed consent, abide by the study requirements, and agree to return for the required follow-up

Exclusion Criteria:

* failed or incomplete revascularization
* patients with chronic heart failure NYHA IV
* patients with acute coronary syndrome
* patients with severe pulmonary hypertension
* patients who are assigned to conservative PAD treatment (according to the treating physician's decision)
* refusal or inability to give informed consent
* patients who are enrolled into another clinical trial