Arterial disorders
Introduction:Ischemia is defined as perfusion (blood supply) that is inadequate to meet the metabolic demands of the end organ.
Arterial disorders represent the most common cause of morbidity and death in western societies. Much of this is due to the effects of atheroma on the arteries supplying the heart muscle (coronary thrombosis and myocardial infarction) and brain (stroke).
Peripheral vascular disease (PVD), commonly referred to as peripheral arterial disease (PAD) or peripheral artery occlusive disease (PAOD), refers to the obstruction of large arteries not within the coronary, aortic vasculature, or brain. i.e. disease of the major arteries of the limbs.
Peripheral arterial disease includes:
Acute arterial occlusion
Chronic arterial occlusion
Aneurysms
Chronic Arterial Occlusion:
The most common cause of chronic arterial occlusion is atherosclerosis. Other causes include; arteritis, vasospastic disorders, compression by tumor, bone, muscle or fibrous bands. Chronic ischemia results from gradual stenosis or occlusion of the major blood supply of an organ resulting in inadequate tissue perfusion.Atherosclerosis:
Atherosclerosis related cardiovascular disease is the most common cause of morbidity and mortality in the united states.Question? What is the difference between arteriosclerosis and atherosclerosis?
Arteriosclerosis generally refers to the generalized thickening and hardening of the artery which usually occurs due to increase amount of basement membrane and plasma protein deposition. It is not necessarily pathogenic but may be due to aging process. Commonly seen in hypertensive patients. whereas atherosclerosis refers to the process of lipid deposition in the intimal layer of the artery with affection of its lumen.Risk factors for atherosclerosis:
Hyperlipidemia
Hypertension
Diabetes mellitus
Obesity and decrease physical activity
Smoking
Male sex
Advanced age
Pathogenesis of an atheroma:
Many theories have been proposed to explain the occurrence of atherosclerosis the most accepted being "Response to injury hypothesis by Ross". The whole process starts with endothelial injury leading to precipitation of LDL and cholesterol at the site of injury. These are rapidly engulfed by macrophages, smooth muscle cells and endothelial cells forming what is called as "foam cells". Aggregation of foam cells lead to the formation of fatty streaks. These fatty streaks will be covered by a fibrous covering separating it from the arterial lumen and the macrophages and smooth muscle cells eventually burst releasing its lipid rich material to the core of the atheroma. The atheroma continues to increase in size with thinning of its overlying covering until the plague eventually ruptures into the arterial lumen releasing its lipid core which is highly thrombogenic leading to fibrin and platelet deposition and arterial occlusion.Clinical features:
Intermittent claudication: cramp like pain felt in the muscles that is:Brought on by walking;
Not present on taking the first step (unlike osteoarthrosis);
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. The distance the patients walks before experiencing the pain is called claudication distance and as the disease progress this claudication distance decreases. However with successful treatment claudication distance can be increased.
Intermittent claudication is less noticed in the upper extremity due to the less muscle mass, and intermittent use when compared to the lower limb.
Bilateral buttock claudication plus sexual impotence resulting from arterial insufficiency is called Leriche’s syndrome. This is due to occlusion of the distal aorta and both iliac vessels.
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
Coldness, and color change. An ischemic limb is usually cold but the limb takes the temperature of its surrounding so it may feel warm in a warm environment. Color changes vary from pallor to dusky cyanosis depending on the degree of ischemia. When mottling occurs it is a sign of impending tissue loss (mottling: alternating areas of pallor and cyanosis not blanching on pressure)
Ulceration and gangrene; usually non healing ulcers in the distal part of the limb.
Reduced sensation, numbness, and paraesthesia. Numbness and parasthesia tend to occur early while reduced sensation is a sign of severe ischemia.
Motor weakness occurs in late stages as the patient gradually notices inability to move his toes and foot.
Absent or diminished pulses distal to the arterial occlusion. However in patients with arterial stenosis or occlusion with well developed collateral circulation, the distal pulse may be maintained at rest but exercising the patient to the degree of claudication may make a previously palpable pulse disappear (disappearing pulse).
Arterial bruit indicates turbulence, suggesting stenosis, and is conducted distally
Beurger's angle. Affected limbs tend to blanch on elevation and develop a purple color on dependency The angle at which the limb becomes pale is called Beurger's angle. The smaller the angle the more severe the ischemia.
Relationship of symptoms to site of ischemia
Site of disease
Clinical findings
Aortoiliac obstruction
Claudication in buttocks, thighs, and calves, with impotence
Femoral and distal pulses absent in both limbs.
Iliofemoral obstruction
Unilateral claudication in the thigh and calf and sometimes the buttock
Unilateral absence of femoral and distal pulses
Femoropopletial obstruction
Unilateral claudication in the calf
Femoral pulses palpable with absent popletial and distal pulses
Distal obstruction
Claudication in the foot, occasionally in the calf
Femoral and popletial pulses palpable with absent distal pulses
Investigations:
Imaging studies are indicated to confirm arterial insufficiency and to localize the site and degree of occlusion or stenosis. Commonly used imaging techniques include
Doppler ultrasound: portable hand held device for clinic and ward examination, flow within an artery is converted into audio signals by the device. 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).
Duplex ultrasound: A duplex scanner uses B-mode ultrasound to provide an image of vessels. It is non-invasive and cost effective.
Angiography (gold standard): Classical angiography involves the injection of a radio-opaque solution into the arterial tree. It is an invasive procedure and generally only advised in patients who intervention is needed. Complications include thrombosis, hematoma formation, arterial dissection, renal dysfunction and allergic manifestations.
CT angiography and Magnetic Resonance Angiography (MRA) but still image quality is less than that for angiography.
Patients with arterial disease tend to be elderly and atherosclerosis is a generalized 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.
Treatment:
I- Non-surgical treatment:Stop smoking
Control of blood sugar
Reduce blood lipid
Reduce weight
Regular exercise to the limit of claudication (doubles the claudication distance over 6 months)
Drugs: a. Antiplatelets e.g.; aspirin, clopidogrel, …etc.
Vasodilators e.g.; tolazoline, calcium canal blockers, pentoxifylline,…etc.
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. It is relatively a simple procedure done under local anesthesia with less cost, hospital stay and mortality rate when compared to surgery. However it still carries the same hazards of hematoma, arterial dissection, aneurysm formation, renal failure and allergic manifestations with less patency rates than that of surgery.
New advances in angioplasty include; laser angioplasty and catheter atherectomy.
III- Surgical treatment:
Surgical options include:
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)
Surgical endarterectomy: Endarterectomy is the general term for the surgical removal of plaque from an artery that has become narrowed or blocked.
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.
Amputation. When all other treatment modalities fail to relieve the
Beurger's disease (Thromboangitis Obliterans):
Beurger's disease also known as thromboangitis obliterans is a Progressive inflammatory segmental disease of small & medium sized artery. It is exceedingly rare in females and not observed in nonsmokers. The cause of Beurger's disease remains unclear but with some evidence of an autoimmune process. The lesions occur in the upper and lower extrimities and in superficial veins as well as arteries. It is characterized by panangitis involving all layers of the blood vessel as well as an inflammatory induced thrombosis.Etiology: Unknown but high association with smoking, high blood viscosity, and hyper-coagulability state.
Diagnosis: Clinically & Angio → segmental obliterations of small & medium sized a. (corkscrew, Corrigan).
Treatment:
Pain relief: narcotic, analgesia, N.block, Sympathectomy ….
Strictly stopping smoking.
Drugs: anticoagulants, dextran, steroids, pentoxiphylline.
The role of Surgery is limited → arterial reconstruction, microvascular transplantations (omentum), all have limited role and mostly ending with amputation.
Raynaud's disease:
Recurrent vasospastic episodes resulting in closure of small artery & arterioles of distal parts of digits, in response to exposure to cold, emotional stress or tobacco. It is an idiopathic condition that usually occurs in young women and affect the hands more than the feet.Stages:-
Pallor → sever spasm (↓ blood supply) → anorexic metabolism (hypoxia) → metabolic products → dilatation of capillary & venules.
Cyanosis → less spasm → small amount of blood enters the digital arteries which become rapidly deoxygenation → cyanosis.
Ruber → vasoconstriction ends→ entry of excessive amount of blood to the already dilated capillaries and venules → reddish discolouration.
The capillaries and venules return to their normal size → return normal blood flow to the digit → the hand returns to its normal color.
These changes are usually accompanied by uncomfortable sensation by the patient, uncommonly rest pain. Ischemic finger tip ulceration rarely occurs.
It is usually bilateral although may be more severe in a specific limb and feet can be involved. And peripheral angiography is usually normal.
Diagnosis:
Clinical history with normal vascular imaging.
Clinical tests e.g.; digital artery pressure changes in response to temperature, finger tip temperature recovery post emersion in ice water,...etc.
Treatment:
Conservative by reassurance and avoiding exposure to cold and wearing worm clothes & gloves and, avoiding tobacco.
Drugs like: vasodilators (calcium canal blockers) and antiplatelets
Surgery: Sympathectomy.
Raynaud's syndrome:
Similar presentation to Raynaud's disease but usually in older patients and more severe in nature. Usually associated with underlying arterial disease as arteritis, microembolization and others. It is commonly associated with ischemic ulcers.
It is commonly associated with collagen vascular disease e.g.; systemic lupus arythmatosus, and rheumatoid arthritis. Also seen in those who commonly use vibrating tools so then the name "vibrating white fingers"
Diagnosis:
Peripheral vascular imaging detects abnormal arteries
Digital artery pressure has a lower base line when compared to normal
Treatment:
Mainly directed to underlying cause
Avoidance of cold exposure
Calcium canal blockers, steroids and other vasodilators may be used
Surgical treatment less effective with higher number of patients ending with amputation.
Patients with vibrating white fingers should avoid using vibrating tools