A 6 year old boy presented in March 2012 to a tertiary vascular centre with a 2 day history of an acutely ischaemic right foot, with restricted walking distance. On examination, the foot was pale and cold; there was a palpable right femoral pulse with absent popliteal and pedal pulses. At the time of presentation, the patient was otherwise well, with no known past medical history. He was started on a heparin infusion after review by the vascular team.
Duplex ultrasound of the right lower limb arteries suggested that there was an occlusion of the superficial femoral artery at the level of the adductor hiatus. There was evidence of collateralisation; dampened arterial flow reappeared in the distal popliteal artery and the crural vessels to the ankle.
Subsequent computed tomography angiography showed that there was a 1.6 cm thrombosed right popliteal artery aneurysm, which was partially calcified; there was triple vessel runoff to the ankle (Fig. 1).
Surgery was performed as an emergency on the day of admission; a right femoropopliteal bypass with reversed great saphenous vein was performed using a medial approach, along with a ligation of the popliteal aneurysm. The long saphenous vein was harvested from mid-thigh to below the knee. The superficial femoral artery was identified and controlled at the level of the adductor hiatus. Below the knee, the popliteal artery was dissected and controlled below the aneurysm. In total, 1,000 units of heparin was administered, and the clamps were put in place.
The upper anastomosis of the reversed saphenous vein was end to side. Tunnelled via the popliteal fossa, the graft was deliberately left long in order to accommodate growth. The popliteal artery was dissected and ligated below the aneurysm and the distal anastomosis was end to side.
There were good pulses in the graft, and distal Doppler signals were present throughout.
In the post-operative period there were no complications. The heparin infusion was stopped the day after surgery. An ultrasound scan confirmed a patent graft. The patient complained of headaches, but these were chronic and had not worsened during his admission.
Following discharge there were no issues regarding his right leg for almost three years; however, in 2015 he re-presented to the vascular clinic with right foot numbness, which was triggered by cold temperatures. It was not positional, and there were no concerning clinical features or on duplex ultrasound of the graft; this was managed conservatively as vasospasm.
It was chosen to follow up yearly with duplex ultrasound to screen for stenosis of the graft; all scans have shown a patent graft, with good flow. The thrombosed popliteal aneurysm is stable in size (in 2017 the aneurysm was measured at 1.4 cm).
Over six years later, in September 2018, the patient presented with a two week history of pain in his right calf and foot. He was unable to walk long distances or play football for more than a few minutes; however, there was no rest pain. The right foot was seen to be paler that the left, particularly after a warm bath.
On examination there was a pulse present in the graft; however, there was no dorsalis pedis or posterior tibial pulse. Right foot capillary refill was also slower. A duplex ultrasound scan done on the same day suggested that there was a small amount of thrombus in the graft with some associated dilation; the graft remained patent. There was, however, evidence of an obstruction of the anterior tibial and mid-posterior tibial artery, with good collateral flow. The most likely explanation for these findings is that the thrombus in the graft had embolised into his native tibial vessels. After discussion with the haematology team, the plan was to anticoagulate with low molecular weight heparin for at least three months.
Follow up one week later showed a better perfused right foot with a biphasic Doppler signal present in the anterior and posterior tibial arteries. The hope is that collateralisation will resolve the symptoms, while the anticoagulation plan should reduce the risk of further embolic events.