Section 3 Thrombosis

Definition:
Thrombosis is the formation of a blood
clot within the vascular system during life.
The blood clot is adherent to the vessel
wall.
Etiology and Pathogenesis
Endothelial injury:
① Causes:
atherosclerosis (probably the single most
important cause),
myocardial infarction,
cardiac surgery,
inflammatory or immunologic injuries to the
heart valves or blood vessels.
(1)
Etiology and Pathogenesis
Endothelial injury:
② Mechanisms:
a. Adhesion of platelets to exposed collagen at the site of
endothelial damage.
b. Secretion of adenosine diphosphate (ADP) and
thromboxane A2 by the adherent platelets.
c. ADP and thromboxane induce platelet aggregation
d. Activation of blood coagulation by:
(i) The intrinsic pathway, initiated by collagen activation of
FactorⅫ
(ii) The extrinsic coagulation pathway, initiated by tissue
factor, derived from damaged endothelium
(1)
Slide 5.5(from
Robbins Basic Pathology,2003, a litter be changed)
(from Robbins Basic Pathology,2003, a litter be changed)
Slide 5.6
(from Robbins Basic Pathology,2003, a litter be changed)
Slide 5.7
(from Robbins Basic Pathology,2003, a litter be changed)
Slide 5.8
Slide 5.11
Etiology and Pathogenesis
(2) Changes in blood flow:
① Stasis
② Disruption of laminar flow.
Etiology and Pathogenesis
(3) Changes in the constitution of the blood:
Hypercoagulability
① Following major surgery or trauma
② In pregnancy and parturition
③ In some users of the oral contraceptive pill
④ After splenectomy
⑤ In endotoxic shock, hypersensitivity reactions.
⑥ In association with some tumors.
Photo is offered by Prof. Orr
参照武忠弼 病理学规划教材第一版 人民卫生出版社修改

Steps in the formation of a thrombus

Morphological types of thrombi
(1) pale thrombus
Constitution: alternating layers of platelet
Location: arteria, cardiac valves and the
initiative part of venous thrombus
(2) red thrombus
Constitution: coagulated red blood cells
Location: at the end part of venous
thrombus
(3) mixed thrombus
Constitution: fibrin with meshed red blood cells
between platelet layers
Location: at the middle part of venous
thrombus,ball thrombus in cardiac atrium
(4) Fibrin thrombus( Microthrombus)
Constitution: fibrin
Location: microcirculatin in DIC
Consequences of thrombosis:
(1)
(2)
(3)
(4)
Resolution:
Organization and re-canalization.
Detachment: thromboembolism
Calcification: intravascular "stones" are formed.
Marked passive
congestion
of the left lower leg
in a patient with a
deep venous thrombus
(Photos are offered by Prof. Orr)
Surgical dissection
of the thrombus.