Medical Parasitology II lec 9& 10.pptxyx

Of course. Here are comprehensive, lecture-grade notes for medical students on Embolism and Infarction, structured according to your provided subtopics.

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General Pathology 2: Detailed Notes

1. Embolism

1. Definition

An embolus is a detached, intravascular solid, liquid, or gaseous mass that ...

Of course. Here are comprehensive, lecture-grade notes for medical students on Embolism and Infarction, structured according to your provided subtopics.

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General Pathology 2: Detailed Notes

1. Embolism

1. Definition

An embolus is a detached, intravascular solid, liquid, or gaseous mass that is carried by the blood to a site distant from its point of origin. The process of this material lodging in and obstructing a blood vessel is called embolism.

· Key point: The vast majority of emboli are dislodged thrombi (thromboembolism), but other types include fat, air, amniotic fluid, and tumor cells.

2. Types

Emboli are classified based on their physical nature and composition:

1. Thromboembolism: Dislodged blood clot (most common ~95%).
2. Fat Embolism: Globules of fat marrow, typically from long bone fractures.
3. Air/Gas Embolism:
· Air Embolism: Air introduced externally (e.g., surgery, trauma).
· Decompression Sickness: Nitrogen bubbles forming from solution in the blood.
4. Amniotic Fluid Embolism: Amniotic fluid, fetal cells, and debris entering the maternal circulation.
5. Septic Embolism: Infected material (e.g., from bacterial endocarditis).
6. Tumor Embolism: Clusters of tumor cells (a mechanism for metastasis).
7. Foreign Body Embolism: e.g., catheter fragments, talc.

3. Thromboembolism

This is the most frequent type of embolism, originating from a thrombus.

· Arterial Thromboembolism:
· Origin: Most commonly arise from thrombi in the heart (e.g., left ventricular wall thrombus post-MI, left atrial thrombus in mitral stenosis or atrial fibrillation). Less commonly, from aortic aneurysms or ulcerated atherosclerotic plaques.
· Impact Site: They travel downstream and most often lodge in the lower extremities (~75%). Other sites include the brain (causing stroke), intestines, kidneys, and spleen.
· Consequence: Ischemia and infarction of the affected tissue.
· Venous Thromboembolism:
· Origin: Almost always arise from Deep Vein Thrombosis (DVT) in the legs, particularly the femoral, iliac, and popliteal veins.
· Impact Site: These emboli travel towards the heart and into the pulmonary circulation.
· Pulmonary Thromboembolism (PTE):
· Definition: The obstruction of the pulmonary arterial tree by a venous embolus.
· Spectrum of Consequences:
· Massive PTE: A large, saddle embolus at the pulmonary artery bifurcation or a significant occlusion (>60% of the pulmonary circulation) can cause sudden death due to acute right heart failure (acute cor pulmonale).
· Medium-sized PTE: Obstruction of medium-sized arteries often causes pulmonary hemorrhage but usually not infarction because of dual blood supply (bronchial arteries). It presents with pleuritic chest pain, hemoptysis, and dyspnea.
· Small PTE: Often clinically silent, but multiple small emboli over time can lead to pulmonary hypertension and chronic cor pulmonale.
· Infarction: Occurs in patients with pre-existing cardiopulmonary compromise (e.g