Aneurysms - Pathology - ATOT

Topic: Aneurysm
Faculty: Pathology
Course: ATOT 2nd year

- Aneurysm: Definition, types, pathogenesis
- Aortic dissection

Reference: Ramadas Nayak - Textbook of Pathology for Allied Health Sciences

1. ANEURYSM Dr. Salman Ansari MBBS

2. Aneurysm Definition Types Pathogenesis Aortic dissection Effects of hypertension

3. Aneurysm Definition : localized, abnormal, permanent dilation of a blood vessel or the heart due to weakening of wall (“LAPD”: localised, abnormal, permanent dilation) Can be congenital or acquired

4. Types of aneurysms Classified on the basis of: Origin Location Appearance Pathogenetic mechanism Composition of wall

5. Origin Congenital: present since birth Acquired: atherosclerosis(commonest) Marfan’s syndrome Syphilis trauma

6. Location Depending upon which type of blood vessel is involved Artery Vein heart

7. Appearance Based on shape of aneurysm Fusiform: spindle-shaped Saccular: spherical outpouching Cylindrical: parallel dilatation serpentine dissection/dissecting hematoma: when blood enters/dissects between the layers of the arterial wall Arteriovenous or racemose: communication between an artery and vein

8. Pathogenetic mechanism Based on pathogenetic mechanism: Atherosclerotic (arteriosclerotic) aneurysms are the most common type. Syphilitic (luetic) aneurysms found in the tertiary stage of the syphilis. Dissecting aneurysms (Dissecting haematoma) in which the blood enters the separated or dissected wall of the vessel. Mycotic aneurysms which result from weakening of the arterial wall by microbial infection. Berry aneurysms which are small dilatations especially affecting the circle of Willis in the base of the brain

9. Composition of wall True aneurysm : involves all three layers of wall(intima, media and adventitia) f alse aneurysm/pseudoaneurysm : due to trauma, only one layer of wall is involved - a hematoma develops in this layer

10. Pathogenesis Aneurysm develops due to weakening of the vessel wall either due to: 1. Inadequate abnormal synthesis of connective tissue of the vessel wall or 2. Increased degradation of connective tissue.

11. Aortic dissection Definition : when blood from aortic lumen enters into the aortic wall and travels along the layers of media to form a blood-filled space within the aortic wall If it ruptures through the adventitia, it is fatal Etiology : hypertension Marfan syndrome Classification : Type A and type B

12. Morphology : Dissection occurs between middle and outer thirds of tunica media May either out through adventitia into thorax/abdomen Sometimes, it may open back into lumen of aorta, creating a “false channel”(double lumen) Clinical features : Sudden onset of severe pain, radiating to the back If rupture occurs, leads to death

13. Complications Rupture, leading to massive hemorrhage and death Compression of adjacent structures embolism

14. Hypertension Definition : Systolic blood pressure above 160 mm Hg and/or diastolic pressure above 90 mm Hg. Causes : Primary/essential/idiopathic hypertension: 95% of cases Secondary hypertension: when there is an identifiable cause

15. Consequences of hypertension Risk factor : hypertension is a major modifiable risk factor for atherosclerosis Diseases produced : HTN can lead to: Cardiac hypertrophy Congestive heart failure(hypertensive heart disease) Ischemic heart disease(IHD) Subarachnoid hemorrhage Hypertensive encephalopathy Accelerated or malignant hypertension : Rapid rise in BP(SBP>200 mmHg or DBP>120 mmHg), which can result in: Renal failure Retinal hemorrhage

16. Summary Definition “LAPD” Types Origin Location Cause Composition of wall Shape

17. References: Ramadas Nayak Textbook of Pathology for Allied Health Sciences Questions: [email protected] For notes: