Embolism 1

8/14/2019 Embolism 1

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EMBOLISM

The process of partial or completeobstruction of some part ofcardiovascular system by any masscarried in the circulation.

The transported intravascular mass

detached from its original is calledEMBOLUS.


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Types:

1. Depending upon the matter: Solid eg: thromboembolism,

atheromatous material, tumor cells. Liquid eg: fat globules, amniotic fluid,

bone marrow. Gaseous eg: air, other gases.

2. Depending upon whether infected or not: Bland- when sterile Septic- when infected


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3. Depending upon source:

Cardiac emboli from left side of

heart. Arterial emboli from systemic

arteries.

Venous emboli eg: pulmonaryarteries

Lymphatic emboli


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4. Depending upon flow of blood:

Paradoxical embolus or crossed

embolus: an embolus which iscarried from the venous circulationto the arterial side or vice versa.

Retrograde embolus: An embolus

which travels against the flow ofblood


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Thromboembolism: detached thrombus or part ofthrombus constitutes common type of embolism.

Arterial (systemic) thromboembolism: Causes within heart(80-85%):These are mural

thrombi in left atrium or left ventricle, vegetationson the mitral or aortic valve, prosthetic heartvalves.

Causes within arteries: emboli developing in relation

to atherosclerotic plaques, aortic aneurysm,pulmonary veins & paradoxical arterial emboli fromsystemic venous circulation.


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Effects of arterial emboli: depends upontheir size, site of dislodgement &adequacy of collateral circulation.

1. Infarction: organ or affected part of

organ spleen, kidneys, brain, intestine.2. Gangrene: following infarction in the

lower limbs.3. Arteritis & mycotic aneurysm: from

bacterial endocarditis.4. Myocardial infarction: following coronary

embolism.5. Sudden death: following coronary

embolism or embolism in middlecerebral artery.


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Venous thromboembolism: may arisefrom following source.

Thrombi in veins of lower legs. Thrombi in pelvic veins.

Thrombi in veins of upper limbs.

Thrombosis in cavernous sinus of thebrain.

Thrombi in right of heart.


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EMBOLISM

Effect of venous embolism isobstruction of pulmonary arterialcirculation.

Pulmonary thromboembolism:

common fatal form of venousthromboembolism in which there isocclusion of pulmonary arterial tree.


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Pulmonary thromboembolism

Etiology: Common in hospitalized or bed-ridden patients.

Thrombi originating from large veins inlower limbs (popliteal, femoral, iliac).

Less common, thrombi in varicosities of

superficial veins of the legs & pelvic veins.


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Pathogenesis: Thrombi detached fromany of above site producethromboembolism into right side of

heart. If thrombus is large & impacted at thebifurcation of the main pulmonaryartery (saddle embolus) or may be

found in right ventricle or its outflow. Commonly, multiple emboli or a large

embolus may be fragmented intosmaller emboli & impacted in number

of vessels, affecting lower lobes.


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EMBOLISM

Rarely, paradoxical embolism may occurfrom right heart into left heart throughatrial or ventricular septal defect.

Consequences: Depend on size ofoccluded vessel, number of emboli &cardiovascular status of patient.

Sudden death: Massive pulmonaryembolism. If death delayed thendyspnoea, chest pain & shock.

Acute cor pulmonale: Multiple small

emboli may obstruct- right heart failure.


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Pulmonary infarction: obstruction ofsmall size arteries. Features-

fibrinous pleuritis, haemoptysis &dyspnoea.

Pulmonary hemorrhage: obstructionof terminal branches (end arteries).

Features haemoptysis, dyspnoea,chest pain.


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Resolution: Small pulmonary emboliare resolved by fibrinolytic activity.

Pulmonary HTN, Chr. Cor pulmonale &pulmonary arteriosclerosis: Multiplesmall emboli undergoing healing thanresolution.


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Systemic embolism: Arterial embolismarising from thrombi from diseasedheart, especially left heart.

Diseases of heart: MI RHD Cardiomyopathy Congenital heart disease Infective endocarditis Prosthetic heart valves


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Consequences:

Infarction at the site of lodgment

include in descending order offrequency, lower extremity, brain &internal organs like brain, spleen,kidney, intestines.


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Tumor embolism:


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Fat embolism: Obstruction of arterioles &capillaries by fat globule. Obstructionby adipose tissue fragments is known

as FAT TISSUE EMBOLISM.Causes:

Traumatic :

1. Trauma to bones2. Trauma to soft tissue- laceration of

adipose tissue & in puerperium due toinjury to pelvic fatty tissue.


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Non-traumatic:

1. Extensive burns

2. Diabetes mellitus

3. Fatty liver4. Pancreatitis

5. Sickle cell anemia

6. Decompression sickness7. Inflammation of bones & soft tissue

8. Extrinsic fat & oils introduced intobody


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Pathogenesis:

1. Mechanical theory

2. Emulsion instability theory3. Intravascular coagulation theory

4. Toxic injury theory


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Consequences:

Pulmonary fat embolism:

Systemic fat embolism:


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Amniotic fluid embolism:

During labour & in immediate post-partum period, the contents of

amniotic fluid may enter the uterineveins & reach right side of heartresulting in fatal complications.

Amniotic fluid embolus: epithelialsquames, vernix caseosa, lanugohair, bile from meconium & mucus.


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Clinical syndrome:

Sudden respiratory distress & dysponea

Deep cyanosis

Cardiovascular shock

Convulsions

Coma

Unexpected death- mechanical blockage,anaphylactoid reaction, DIC,

haemorrhagic manifestations due tothrombocytopenia & afibrinogenaemia.


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Gas embolism: Air, nitrogen & other gasescan produce bubbles within circulation &obstruct the flow.

Air embolism: when air is introduced intoarterial or venous circulation.

Venous air embolism: Causes

1. Operations on head, neck, & trauma.

2. Obstetrical operations & trauma.

3. Intravenous administration of blood &fluid.

4. Angiography.


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Effects depend upon following factors:

1. Amount of air- 100-150 ml fatal

2. Rapidity of entry.

3. Position of patient.4. General condition of patient.

Arterial air embolism:1. Cardiothoracic surgeries.

2. Paradoxical air embolus

3. Arteriography


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EMBOLISM

Decompression Sickness/Caissons disease/Divers Palsy: Special form of gas embolism.

Pathogenesis: produced when the individualdecompresses suddenly, either from high

atmospheric pressure to normal level, or fromnormal pressure to low atmospheric pressure.

Effects depend upon:

Depth or altitude

Duration of exposure to altered pressure

Rate of ascend or descent

General condition of the individual


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Clinical Effects:

Acute

1. The bends: patient doubles in bed dueto acute pain in joints, ligaments &tendons.

2. The chokes: due to accumulation of

bubbles in the lungs, resulting in acutepulmonary distress.

3. Cerebral effects: vertigo, coma &sometimes death.


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Chronic

1. Avascular necrosis of bones :eg- headfemur, tibia, humerus.

2. Neurological symptoms : ischaemic necrosisin CNS. Peraesthesias & paraplegia.

3. Lung involvement: haemorrhage, oedema,emphysema & atelactasis. Dyspnoea, non-productive cough & chest pain.

4. Skin manifestation: itching, patchyerythema, cyanosis & oedema


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Embolism 1