# Arterial Embolus and Acute Limb Ischaemia

> Arterial embolus for FMGE Surgery: six Ps of acute limb ischaemia, atrial fibrillation source, Fogarty embolectomy and reperfusion complications.

- Canonical URL: https://prepelephant.com/topics/fmge/surgery/arterial-embolus
- Exam / course: FMGE · Subject: Surgery
- Publisher: PrepElephant (https://prepelephant.com) — Prepared and reviewed by the PrepElephant Academic Review Team
- First published: 2026-10-02
- Last updated: 2026-10-02
- How to cite: "Arterial Embolus and Acute Limb Ischaemia", PrepElephant, https://prepelephant.com/topics/fmge/surgery/arterial-embolus

## Direct answer

An arterial embolus is a clot that travels and lodges at a bifurcation — most often from the heart in atrial fibrillation or after myocardial infarction — producing sudden severe ischaemia of a previously normal limb. The limb shows the six Ps: pain, pallor, pulselessness, paraesthesia, paralysis and poikilothermia, and clinical severity is graded by sensory and motor loss. Treatment is immediate intravenous heparin and emergency embolectomy with a Fogarty balloon catheter, with fasciotomy for reperfusion compartment syndrome.

## What you must remember

- Sources in order of exam frequency: the heart in atrial fibrillation, after recent myocardial infarction and from diseased or prosthetic valves; aneurysms and paradoxical emboli account for the rest.
- The six Ps define the syndrome; the commonest landing sites are the aortic bifurcation (saddle embolus with bilateral signs) and the common femoral and popliteal bifurcations.
- The limb is threatened when sensation and motor power are lost — fixed mottling with anaesthesia and rigid muscles means irreversible infarction; calf tenderness on squeeze and rest pain are earlier warnings.
- Management begins with intravenous unfractionated heparin and analgesia at once; the diagnosis in a limb without prior claudication is clinical, and imaging must never delay embolectomy in a threatened limb.
- Balloon catheter embolectomy with a Fogarty catheter is the standard operation; catheter-directed thrombolysis is an alternative in selected cases where the limb is not immediately threatened.
- After revascularisation watch for reperfusion injury — hyperkalaemia, acidosis and myoglobinuria threatening the kidneys — and perform fasciotomy for compartment syndrome; echocardiography then hunts the source.
- Acute-on-chronic thrombosis of an atherosclerotic artery differs from a true embolus: collaterals have developed, the deficit is less dramatic, the limb bears chronic signs, and management leans on revascularising the underlying disease.

## Common confusion

The exam repeatedly contrasts embolus with thrombosis-in-situ: the embolic limb was normal until the moment of pain, the source is usually cardiac, and the deficit is maximal at the outset; the thrombotic limb has claudication history, chronic trophic changes and less severe deficit because collaterals pre-exist. Candidates also lose marks by ordering a CT angiogram for an obviously threatened limb — the right answer is heparin plus theatre — and by forgetting fasciotomy after successful embolectomy when the calf is tight.

## Exam-focused takeaway

FMGE acute limb ischaemia questions are urgency questions. The sudden pale, pulseless, painful leg in a patient with atrial fibrillation is an embolus: heparin immediately, Fogarty embolectomy urgently, no imaging delay, fasciotomy when the compartments are tight, and monitoring for hyperkalaemia and myoglobinuria after flow returns. Numbness with calf tenderness marks a threatened limb; fixed mottling with paralysis marks a dead one, answered by amputation. The post-event echocardiogram and long-term anticoagulation complete the management pair.

## Frequently asked questions

### What are the six Ps of acute limb ischaemia?

Pain, pallor, pulselessness, paraesthesia, paralysis and poikilothermia — the classic descriptive set for an acutely ischaemic limb.

### What is the commonest source of arterial emboli?

The heart — left atrial thrombus in atrial fibrillation, mural thrombus after myocardial infarction, and vegetations on valves.

### What is the immediate management of a threatened limb?

Intravenous unfractionated heparin with analgesia, followed by emergency Fogarty balloon catheter embolectomy without waiting for imaging.

### Why is fasciotomy needed after embolectomy?

Reperfusion oedema can precipitate compartment syndrome in the calf, so compartment release is performed when compartments are tense or signs appear.

### What systemic danger follows revascularisation?

Reperfusion injury with hyperkalaemia, metabolic acidosis and myoglobinuria causing acute kidney injury — monitor and treat aggressively.

### How is embolic acute ischaemia distinguished from thrombosis?

Sudden maximal deficit in a previously normal limb with a cardiac source favours embolus; claudication history, chronic skin changes and collaterals favour thrombosis of diseased artery.