Atherosclerosis

Atherosclerosis:

Atherosclerosis is the major cause of chronic arterial occlusion. "Response to injury hypothesis" proposed by Ross was the most accepted hypothesis for the formation

of atheromatous plague.

Risk factors for atherosclerosis:

1.     Smoking

2.     Diabetes mellitus

3.     Dyslipidemia

4.     Hypertension

5.     Obesity

6.     Increase age

Clinical features:

1-    Intermittent claudication: cramp like pain felt in the muscles that is:

a.     Brought on by walking;

b.     Not present on taking the first step (unlike osteoarthrosis);

c.      Relieved by standing still (unlike lumbar intervertebral disc nerve compression).

The pain of claudication is most commonly felt in the calf but it can affect the thigh or buttock. Buttock claudication plus sexual impotence resulting from arterial insufficiency is called Leriche’s syndrome.

2-    Rest pain: occurs at rest and in the distal part of the limb (toes and foot). It is exacerbated by lying down or elevation of the foot. Characteristically, the pain is worse at night and it may be lessened by hanging the foot out of bed or by sleeping in a chair

3-    Coldness, numbness, paraesthesia and colour change. The limb takes the temperature of its surrounding.  

4-    Ulceration and gangrene; usually non healing ulcers in the distal part of the limb.

5-    Reduced sensation

6-    Motor weakness

7-    Absent or diminished pulses distal to the arterial occlusion

8-    Arterial bruit indicates turbulence, suggesting stenosis, and is conducted distally

Investigations:

Patients with arterial disease tend to be elderly and atherosclerosis is a generalised disease; if active intervention is contemplated, full assessment is essential. This includes tests for diabetes, ischemic heart disease, COPD, lipid abnormalities, renal disease, coagulation abnormalities …etc.

Investigations specific for arterial disease includes:

1-    Doppler ultrasound: portable hand held device for clinic and ward examination, the doppler detects flow in the vessel but flow doesn't reflect viability. The main advantage of doppler is measurement of the ankle brachial pressure index (ABPI).

2-    Duplex ultrasound: A duplex scanner uses B-mode ultrasound to provide an image of vessels.

3-    Angiography (gold standard): Classical angiography involves the injection of a radio-opaque solution into the arterial tree, generally by a retrograde percutaneous catheter method (Seldinger technique) usually involving the femoral artery.

4-    CT angiography and Magnetic Resonance Angiography (MRA)

Treatment:

I-                   Non-surgical treatment:

1-    Stop smoking

2-    Control of blood sugar

3-    Reduce blood lipid

4-    Reduce weight

5-    Regular exercise to the limit of claudication

6-    Drugs:

a.     Antiplatelets e.g.; aspirin, clopidogrel, …

b.     Vasodilators e.g.; tolazoline, calcium canal blockers, pentoxifylline,

II-                Percutaneous Transluminal Angioplasty (PTA):

Arterial occlusive disease may be treated by inserting a balloon catheter into an artery and inflating it within a narrowed or blocked area with or without the insertion of a stent across the lesion. This is done usually percutaneously and under radiological imaging.

III-              Surgical treatment:

Surgical options include:

1-    Bypass surgery e.g. femoro-popliteal bypass, aorto-femoral bypass, aorto-bifemoral bypass, and others. Bypass surgery may use an autologus graft (e.g.; saphenous vein graft) or a synthetic graft (e.g.; Dacron or PTFE grafts)

2-    Surgical endarterectomy: Endarterectomy is the general term for the surgical removal of plaque from an artery that has become narrowed or blocked.

3-    Sympathectomy: is a surgical procedure where certain portions of the sympathetic nerve trunk are destroyed. This changes the blood distribution to the limb by eliminating the sympathetic vasoconstrictive action directing more blood to the bone and skin therefore reducing pain sensation. Sympthectomy may be done surgically or chemically by injecting various substances into the sympathetic chain under radiological guidance.

4-    Amputation. When all other treatment modalities fail to relieve the rest pain or promote healing of an ischemic ulcer.