Hemodynamic Disorders L18,19

Question 1

Hemostasis

Answer 1

The normal process of keeping blood in a fluid state while rapidly forming a clot at an injury site.

Question 2

Thrombosis

Answer 2

A pathological condition where a solid blood clot forms within the circulatory system (unruptured vessels).

Question 3

What are the three main abnormalities that can lead to thrombus formation?

Answer 3

Virchow’s triad:
1. Endothelial injury
2. Stasis or turbulence of blood flow
3. Blood hypercoagulability

Question 4

Why is endothelial injury a risk factor for thrombosis, particularly in the heart and arteries?

Answer 4

*Normal high blood flow rates in these areas prevent clotting by minimizing platelet adhesion and diluting clotting factors.

*Endothelial damage exposes underlying tissue, which platelets can adhere to, and triggers clotting factor release.

Question 5

How do turbulence and stasis contribute to thrombosis?

Answer 5

GDisrupt laminar flow, bringing platelets into contact with the endothelium.

*Prevent dilution of activated clotting factors by fresh blood flow.

*Hinder the arrival of clotting factor inhibitors.

*May promote endothelial injury, leading to platelet adhesion.

Question 6

What are some causes of turbulence and stasis?

Answer 6

*Ulcerated atherosclerotic plaques (expose subendothelial tissue and cause turbulence).

*Abnormal heart or artery widening (aneurysms).

*Areas of non-contractile heart muscle (e.g., after a heart attack).

*Heart valve stenosis (e.g., mitral valve).

*Hyperviscosity syndromes (thick blood due to conditions like polycythemia).

*Sickle cell anemia (deformed red blood cells that obstruct vessels).

Question 7

What is hypercoagulability?

Answer 7

An alteration in clotting pathways that increases the risk of thrombosis.

Question 8

How does hypercoagulability differ in arterial/cardiac vs. venous thrombosis?

Answer 8

*Less frequent contributor to arterial/cardiac thrombosis.

*Important risk factor for venous thrombosis.

Question 9

What are the two main categories of hypercoagulability disorders?

Answer 9

1.Primary (genetic) disorders (e.g., factor V or prothrombin gene mutations).
2.Secondary (acquired) disorders (caused by various factors).

Question 10

What are some examples of secondary hypercoagulability disorders?

Answer 10

*Cardiac failure or trauma (stasis or injury may be the main cause).

*Oral contraceptives or pregnancy (increased clotting factor synthesis).

*Cancers (release of procoagulant substances by tumors).

*Aging (increased platelet aggregation).

*Smoking and obesity (unknown mechanisms).

Question 11

What are these microscopic features seen in thrombi, and what do they indicate?

Answer 11

Lines of Zahn are alternating pale (platelet/fibrin) and dark (red blood cell) layers, suggesting antemortem (before death) thrombosis.

Question 12

How can thrombi be distinguished based on lamination?

Answer 12

Postmortem clots typically lack lamination (lines) (bland, uniform).

Venous thrombi may show poorly defined laminations upon careful examination.

Question 13

Types of Thrombi:

Answer 13

Mural Thrombi

Arterial Thrombi

Venous Thrombosis (Phlebothrombosis)

Vegetations

Question 14

Where do mural thrombi form?

Answer 14

Heart chambers or aortic lumen.

Question 15

What are some causes of mural thrombi?

Answer 15

*Abnormal heart contractions (arrhythmias, infarction).

*Endomyocardial injury.

Question 16

What is the typical composition of arterial thrombi?

Answer 16

A loose network of platelets, fibrin, red blood cells, and degenerating white blood cells.

Question 17

What are the common causes of arterial thrombi?

Answer 17

Atherosclerotic plaque buildup and vascular injury (vasculitis, trauma).

Question 18

How do venous thrombi differ from arterial thrombi in composition and location?

Answer 18

*Nearly occlusive (can almost completely block the vein).

*More red blood cells due to slower venous blood flow (stasis thrombi).

*Develop most commonly in the lower leg veins.

*Platelets play a secondary role in their formation compared to the coagulation cascade.

Question 19

What are vegetations, and how can they form?

Answer 19

Thrombi that develop on heart valves. Bacterial or fungal infections can damage heart valves, leading to the growth of large thrombotic masses (infective endocarditis).

Question 20

What are the four main events that can happen to a thrombus after it forms?

Answer 20

1.Propagation: Grows larger with additional platelets and fibrin.

2.Embolization: Breaks off and travels through the bloodstream.

3.Dissolution: Gets broken down by fibrinolytic activity.

4.Organization and recanalization: Triggers inflammation and scarring, potentially reopening the blood vessel partially.

Question 21

What are the four main events that can happen to a thrombus after it forms?

Answer 21

1.Propagation: Grows larger with additional platelets and fibrin.

2.Embolization: Breaks off and travels through the bloodstream.

3.Dissolution: Gets broken down by fibrinolytic activity.

4.Organization and recanalization: Triggers inflammation and scarring, potentially reopening the blood vessel partially.

Question 22

What are the two main clinical effects of thrombi?

Answer 22

1.Obstruction of arteries and veins

2.Source of emboli (fragments that travel and cause blockages elsewhere)

Question 23

How does the effect of a thrombus differ depending on its location (arterial vs. venous)?

Answer 23

*Venous thrombi: More likely to cause congestion and edema, but the biggest risk is pulmonary embolism (traveling to the lungs).

*Arterial thrombi: More likely to cause blockages in critical areas (e.g., heart, brain) leading to tissue death (infarction). They can also embolize.

Question 24

Where do most venous thrombi occur?

Answer 24

Superficial or deep veins of the leg.

Question 25

What are the differences between superficial and deep vein thrombosis?

Answer 25

*Superficial: Causes local swelling, pain, and tenderness, but rarely embolizes.

*Deep: More serious due to higher risk of embolization. May cause pain and edema, but often has no symptoms (50% of cases).

Question 26

What are some risk factors for deep vein thrombosis?

Answer 26

1.Advanced age, bed rest, and immobilization (reduced muscle activity slows blood flow).

2.Cardiac failure.

3.Trauma, surgery, and burns.

4.Pregnancy and postpartum period (amniotic fluid exposure and hypercoagulability).

5.Hypercoagulable states (increased clotting tendency).

Question 27

What is an embolus?

Answer 27

A detached mass (solid, liquid, or gas) traveling in the bloodstream to a distant location.

Question 28

What is the most common type of embolus?

Answer 28

Thromboembolism (a dislodged blood clot).

Question 29

What are some rare forms of emboli?

Answer 29

*Fat embolism (microscopic fat globules from bone fractures).

*Air embolism (gas bubbles in the bloodstream, e.g., from chest injury).

Question 30

What are some less common types of emboli formed from solid material?

Answer 30

*Atherosclerotic emboli (cholesterol debris).

*Tumor emboli (fragments of a tumor).

*Bone marrow emboli (bits of bone marrow).

Question 31

What happens when an embolus lodges in a blood vessel?

Answer 31

It can partially or completely block the vessel, leading to tissue ischemia (lack of oxygen) and necrosis (cell death) downstream.

Question 32

Where do most pulmonary emboli originate from?

Answer 32

Deep leg vein thrombi (above the knee) such as femoral or iliac veins.

Question 33

How does a pulmonary embolus travel to the lungs?

Answer 33

It travels through the right side of the heart before entering the pulmonary arteries.

Question 34

Where do most systemic emboli (arterial) originate from?

Answer 34

Intracardiac mural thrombi (blood clots within the heart).

Question 35

What are the most common sites for systemic emboli to lodge?

Answer 35

1.Lower extremities (75%).

2.Brain (10%).

3.Intestines, kidneys, and spleen. (Least common: upper limbs)