Hemodynamic Disorders (Disorders of blood flow) Dr. Abdelaty Shawky Dr. Gehan Mohamed

* Classification of thrombi: a. According to the color & composition of thrombi. b. According to the site of thrombus. c. According to presence or absence of bacteria.

a. According to the color & composition of thrombi: 1. Pale thrombus: formed of platelets and fibrin with few RBCs. 2. Red thrombus: formed of platelets and fibrin with excess RBCs. 3. Mixed thrombus: containing parts of pale thrombus and parts of red thrombus.

b. According to the site of thrombus: Venous thrombi (the most common): 2. Arterial thrombus: less common. 3. Cardiac thrombi: found in the heart chambers and valves. 4. Capillary thrombi: rare.

Femoral vein thrombosis

Coronary artery thrombosis

Mural thrombus of left ventricle

c. According to presence or absence of bacteria: 1. Septic thrombus: containing pyogenic bacteria. 2. Aseptic thrombi: without bacteria.

1. Venous thrombosis Thrombosis in veins is more common than other sites because of their slow blood flow, thin non-muscular wall and superficial in location. Thrombosis in veins may be either: Thrombophlebitis: occurs in the sitting of inflammation. b. Phlebothrombosis: occurs in the sitting of stasis.

2. Arterial thrombosis Less common than venous thrombosis because of the rapid blood flow and the thick elastic arterial wall which resists injury. Thrombosis occurs in arteries affected by: atherosclerosis. Arteritis. aneurysms. Arterial thrombosis → ischemia → infarction.

3. Cardiac thrombi: found in the heart chambers and valves. Include: Auricular thrombus: in the left atrium over auricular appendages in case of mitral valve stenosis. Mural thrombus in the left ventricle over an area of myocardial infarction. Vegetations: on the heart valves in rheumatic fever, systemic lupus erythematosus, and bacterial endocarditis.

4. Capillary thrombi: in cases of severe acute inflammation and frost bites.

* Fate and complications of thrombi: It depends upon its size & whether it is septic or aseptic. ● Septic thrombi: Fragments by proteolytic enzymes into septic emboli → pyaemic abscesses. ● Aseptic Thrombi: may undergo: - Small thrombi is dissolved and absorbed. - Large thrombus undergoes: 1- Organization ,canalization . 2- Calcification. 3- Fragmentation and embolism.

Thrombus: organized & recanalized

Post mortem Blood Clot A mass of blood elements formed by transformation of fibrinogen to fibrin, in stagnant blood. The clot is dark red with a glistening smooth surface, and is not adherent to the vessel wall. Clotting of blood may be: . Inside the CVS after death (postmortem clots) red yellow

* Differences between thrombus and clot: 1- Occurs in stagnant blood after death 2- Loosely attached 3- Soft and moist 4- Red or yellow 5. Formed of fibrin and blood elements. 6- No lines of Zhan 1- Occurs in circulating blood during life 2- Firmly attached 3- Friable and dry 4- Pale, red or mixed. Formed mainly of fibrin, platelets. 6- May show lines of Zhan

EMBOLISM

* Definition: - Is the process of circulation of insoluble material in the blood and its sudden impaction in a narrow vessel. - This insoluble material is called (embolus).

* Causes & Types of embolism: 1. Thrombo-embolism: the embolus is detached thrombus) 2. Fat embolism: the embolus is fat. 3. Air embolism: the embolus is air bubbles. 4. Parasitic emboli: the embolus is a parasite e.g. bilharzial worms and ova.

5. Tumor emboli: the embolus is groups of tumor cells penetrating the wall of blood vessels especially veins. 6. Amniotic fluid embolism: the embolus is an amniotic fluid embolism during labor.

1. Thromboembolism - According to the site of origin and the site of impaction, there are 3 types: 1. Pulmonary embolism: the embolus coming from the systemic veins and get impacted in pulmonary blood vessels.

2. Portal embolism: the embolus coming from gastrointestinal organs get impacted in the portal veins . 3. Systemic embolism: the embolus coming from the left side of the heart or systemic artery and get impacted in systemic organ e.g. brain, kidney, spleen…….

* Effects of thromboembolism: Effects depends upon: 1- Size of the embolus. 2- Nature of the embolus (septic or aseptic). 3- State of the collateral circulation in the affected site. Effects of pulmonary embolism: Big embolus Medium sized embolus Recurrent Small emboli healthy lung congested lung Sudden death No effect infarction lung fibrosis

Fat embolism * Causes: 2. Extensive burns. 1. Fracture of long bones e.g. femur, humerus. 2. Extensive burns. 3. Trauma to severe fatty liver.

Ischemia * Definition: * Types: 1. Acute ischemia: Deficient arterial blood supply to an organ or tissue due to partial or complete occlusion of its artery. * Types: 1. Acute ischemia: - Sudden and complete occlusion. 2. Chronic ischemia: - Gradual and partial occlusion.

Acute ischemia * Causes: Sudden complete arterial occlusion by: 1. Thrombosis or embolism. (most common) 2. Surgical ligature of the artery. * Effects: Organs with good collateral circulation→ No effect. Organs with poor collateral circulation → infarction .

Chronic Ischemia * Causes: Gradual and incomplete arterial occlusion by: 1. Atherosclerosis. 2. Pressure on the artery by enlarged lymph node, tumor ... etc.

* Effects: Organs with good collateral circulation → No effect. Organs with poor collateral circulation → chronic ischaemic changes; Cellular degeneration, atrophy followed by fibrosis. Clinically manifested e.g. by angina pectoris, intermittent claudication.

Robbins and Cotran’s: Pathologic Basis of Disease. Seventh edition. References: Robbins and Cotran’s: Pathologic Basis of Disease. Seventh edition.