Atherosclerosis & Pvd

Diseases of the Blood Vessels

Dr. Mehzabin Ahmed

Arteriosclerosis It is the hardening of arteries. Includes 3 patterns of vascular characterized by: Thickening Loss of elasticity of the arteries.

diseases

Atherosclerosis: It is the formation of fibrous

plaques, in the tunica intima of the large and medium sized arteries, and contains a lipid core. These plaques are called atheromas.

Monckeberg

medial

calcific

sclerosis:

There are calcific deposits in the tunica media of muscular arteries.

Arteriolosclerosis: It is the thickening of the small arteries and the arterioles by hyaline deposits or due to hyperplasia of the muscle layer as seen commonly in hypertension.

Atherosclerosis It is a degenerative disease of large and medium sized arteries characterized by lipid deposition and fibrosis. Characteristic intimal lesions called atheromas or fibro fatty plaques that protrude into the lumen, weaken the underlying media, and undergo a series of complications.

Morphology The major types of artheromatous lesions are 1)                 Fatty streak 2)                 Fibro fatty plaque 3)                 Complicated plaque

Fatty Streak These are linear elevations most obvious in the thoracic aorta and coronary arteries. They are composed of lipid filled foam cells with T lymphocytes and small amounts of extracellular lipid.

Fibrofatty plaque They are also called atheromas. The basic lesion consists of a raised focal plaque within the intima, having a core of lipid (mainly cholesterol and cholesterol esters) and a covering fibrous cap. The artheromatous plaques appear white to yellow white in colour and impinge on the lumen of the artery. Size: usually 0.3 – 1.5 cm in diameter, they may fuse to form larger masses. 

Cut section: the superficial portion is white and firm (fibrous cap). The deep portions is yellow or whitish yellow and soft center

Components of Atherosclerosis plaques Cells: smooth muscle cells, macrophages, leukocytes Connective tissue, extra cellular matrix including collagen, elastic fibers and proteoglycans Intracellular and extracellular lipid deposits

Distribution of atheromatous plaques Atherosclerosis primarily affects elastic arteries e.g. aortic, carotid, iliac arteries and large and medium sized muscular arteries 1.      Abdominal aorta around the origins of its major branches 2.      Coronary arteries 3.      Popliteal arteries 4.      Descending thoracic aorta 5.      Internal carotid arteries 6.      Vessels of circle of Willis 7.      Arteries supplying the small intestines

Major consequences of AS Myocardial ischemia and infarction: due to involvement of the coronary arteries that result in ischemia of the heart muscles resulting in Ischemic heart disease and infarction on complete cessation of blood supply Stroke: profound ischemia of the cerebrum results in infarction of the brain and a resultant paralysis of the body represented in the affected area. Gangrene of the lower limbs Aortic aneurysms: due to the weakening of the tunica media underlying the plaque Mesenteric occlusion and gangrene of the affected bowel segment.

Complicated Plaque

An atherosclerostic plaque that has undergone a change or complication 1.Thrombosis occurs on disruptured lesions (those with rupture, ulceration, erosion or haemorrhage) 2. Rupture focal rupture or gross ulceration of the luminal surface of atheromatous plaques results in thrombus formation or production of micro emboli 3. Hemorrhage can occur into the plaque 4. Wall weakening The medial atrophy with loss of elastic tissue causes weakness 5. Calcification Advanced lesions may undergo patchy or massive calcification.

Risk factors: major factors Non-modifiable That cannot be changed/controlled i) Increasing age ii) Male gender iii) Family history iv) Genetic predisposition

Modifiable That can be controlled i) Hyperlipidemia ii) Hypertension iii) Diabetes mellitus iv) Cigarette smoking

Lesser Factors •Obesity •Physical inactivity or sedentary lifestyle •Stress •Homocysteine •Postmenopausal estrogen deficiency •High carbohydrate intake •Alcohol consumption •Lipoprotein A •Consumption of hardened fat •Chlamydiae pneumonia infection

Clinical significance AS contributes very largely to morbidity and mortality. But a significant decrease in the risk can be achieved by: Lifestyle modifications with respect to the diet and personal habits (cigarette smoking) Adequate control of hypertension Improvement in the treatment modalities for myocardial infarction and complications of Ischemic heart disease Prevention of recurrences

Peripheral vascular disease Diseases of blood vessels outside the heart and brain. Two types of these circulation disorders: Functional peripheral vascular diseases    

Donot have an organic cause. Donot involve defects in blood vessel structure. Usually short-term effects. Raynaud's disease is an example

Organic peripheral vascular diseases 



Caused by structural changes in the blood vessels, such as inflammation and tissue damage. Buerger’s disease (caused by fatty buildups in arteries) is an example.

Beurger’s disease (Synonym: TAO: Thromboangiitis obliterans A disease of smokers, usually young men, in which the small neurovascular bundles in the extremities become inflamed and undergo thrombosis Thromboangiitis: inflammation and thrombus formation in the artery, obliterans: occlusion or obliteration of the lumen similar to coronary artery disease and carotid artery disease- results in Ischemia and gangrene of the leg, requiring amputation of the leg. mainly in arteries leading to the legs and feet. "intermittent claudication“ pain higher risk of death from stroke and heart attack, due to the risk of blood clots

Risk factors Diabetes Smoking Obesity High blood pressure A family history of the disease Lack of exercise Coronary artery disease Over the age of 65 Hyperlipidemia (high cholesterol)

Symptoms Some of the symptoms you may experience in the affected areas are: 1.   Claudication (dull, cramping pain in hips, thighs, or calf muscle) 2.   Numbness or tingling in the leg, foot, or toes 3.   Changes in skin color (pale, bluish, or reddish discoloration) 4.   Changes in skin temperature, coolness 5.   Impotence 6.   Infection/ sores that do not heal

Gangrene of the foot resulting from Ischemia due to TAO

ANEURYSMS AND DISSECTIONS ANEURYSMS- localized

dilation of a blood vessel or the wall of the heart 



true aneurysm; all layers of arterial wall or attenuated wall of the heart form the boundary false aneurysm (pseudoaneurysm or pulsating haematoma) usually result from rupture of heart

Arterial dissection – blood enters between the layers of the arterial wall

causes Atherosclerosis Cystic medial degeneration of aorta Congenital ( berry aneurysms) Infections (“mycotic” usually in Infective endocarditis, caused by bacterial infection ) Syphilis (luetic aneurysm ) Vasculitis trauma

Aortic aneurysm

Dissection

VEINS Varicose veins –dilated, thin,tortuous,elongated and scarred veins 



caused by loss of competency in the vein valves and support structures,as a result of ageing, prolonged standing , obesity, repeated pregnancies etc. leads to venous congestion, persistent edema hemosiderin stasis pigmentation and/or ischemic stasis ulcers.

Varicose veins in the leg

Varicose veins (contd.) Main sites: superficial veins of the upper and lower legs 

esophageal varices and hemorrhoids as evidence of portal hypertension.  Hemorrhoids also occur in prolonged pelvic

congestion resulting from repeated pregnancies, straining at stools etc.

thrombi that may form in varicose veins very seldom embolize

Thrombophlebitis 

Thrombosis of a deep vein, most often in the leg (90%).  Causes: cardiac failure, pregnancy, neoplasia,

obesity, post operative state, prolonged bed rest, immobilization ,genetic hypercoagulability  Trousseau's migratory thrombophlebitis affects first one vein, then another. The cause is usually cancer of the pancreas, less often another adenocarcinoma

Thrombophlebitis (contd..) 

Other sites : periprostatic venous plexus, pelvic veins in the female, large veins in the skull and dural sinuses(dural sinus thrombosis) ,portal vein

Budd-Chiari syndrome (thrombosis of the hepatic veins) Special variant is phlegmasia alba / cerulea dolens (painful white leg), also called milk leg caused by iliofemoral thrombosis around the time of parturition.

Hypertension Definition: Is a complex multifactorial disease that has both genetic and environmental determinants. Characterized by elevated blood pressure. Sustained Systolic pressure : > 140 mm Hg (normal- 120mm Hg) Sustained Diastolic pressure : > 90 mm Hg (normal- 80mm Hg)

Causes of Hypertension Essential Secondary to other diseases like  Diseases of the Kidneys  Endocrine disorders CVS disorders  Neurologic diseases

Malignant hypertension Rapid rise in BP >120mm Hg of the diastolic BP Renal failure Papilledema Retinal hemorrhages & exudates

Pathogenesis of essential hypertension Genetic:

Mutations/Polymorphisms at several loci Single gene disorders- Unusual 1) enzyme defects- aldosterone metabolism 2) mutations- abnormal proteins of Na reabsorption

Environmental: stress, obesity, smoking, physical inactivity, heavy salt intake

Mechanism Renal ↓ Renal Na ↑ Plasma ↑Cardiac Peripheral Excretion Volume Output Vasoconstriction ↑ BP

Vascular Vasoconstriction & Vascular hypertrophy 1) Behavioural or neurogenic 2) Vasoconstrictors 3) Sensitivity

↑

↑ PR

Consequences Longstanding hypertension leads to hypertrophy of the heart muscles which in turn increase the demand for oxygen and nutrients. Over a period of time when the blood supply fails to keep up to the increased demand the heart goes in for failure. Augment atherosclerotic changes. Predispose for coronary artery diseases and cerebrovascular accidents.

Learning objectives Define the term – Atherosclerosis, aneurysm, varicose veins, hypertension. Explain the pathogenesis of Atherosclerosis. Enumerate the risk factors of atherosclerosis. Enumerate the complications of the atheromatous lesions. Explain the clinical significance of atherosclerotic lesions. Enumerate clinical conditions associated with varicose veins Classify aneurysms. Enumerate the consequences of aneurysms Enumerate common renal, endocrine, cardiovascular and neurologic disorders, which can cause secondary hypertension Explain the pathogenesis of essential hypertension