Cardiac Histopath Qs Flashcards
What are the 3 prinicple components of atherosclerotic plaques?
Cells - including SMC, macrophages, and other leukocytes; ECM including collage, Intracellular and extracellular lipid
What areas are most at risk of atherosclerosis?
Abdominal aora affected more than thoracic aorta. More prominent around origins (ostia) of major branches (turbulent blood flow has low/oscillatory sheer stress which is athrogenic). High laminar flow is protective.
What are the modifiable risk factors for atherosclerosis?
TIIDM, HTN, High cholesterol, smoking
What are the non modifiable risk factors for atherosclerosis?
Gender (Male), increasing age, FHx
Steps of Atherogenesis (7)
- Endothelial injury
- LDL enters intima and is trapped in sub-intimal space
- LDL is converted into modifies and oxidised LDL causing inflammation
- Macrophages take up ox/modLDL via scavenger receptors and become foam cells
- Apoptosis of foam cells causes inflammation and cholesterol core of plaque
- Increase in adhesion molecules on endothelium results in more macrophages and T cells entering the plaque
- Vascular smooth muscle cells form the fibrous cap
Pathogenesis of MI
dynamic interaction between coronary atherosclerosis, plaque rupture, superimposed platelet activation, thrombosis and vasospasm leading to occlusive intracoronary thrombus overlying a disrupted plaque. This results in necrosis secondary to ischaemia
How long must ischaemia last to cause irreversible injury and myocyte death?
Over 20 mins
What liver enzymes is raised after an MI?
ALP
Complications of an MI (mneumonic)
DARTHVADER: Death, Arrhythmia (VF), Rupture (Ventricular wall, septum, papillary muscle), Tamponade (from pericardial effusion), HF, Valve disease (MR), Aneurysm of ventricles (over 4 weeks post MI), Dresslers Syndrome (and other Pericarditis), Embolism (due to mural thrombus), Recurrence of MI
Mechanical Complications of MI (Path guide division)
Contractile dysfunctioon leading to cardiogenic shock, Congestive CF due to ventricular dysfunction, LV infarct leading to papillary muscle dysfunction/necrosis/rupture leading to MR; Cardiac rupture of ventricular wall, septum, papillary muscle; ventricular aneurysm
What is the result of a cardiac rupture of: Ventricular wall, Septum, Papillary muscle?
Ventricular wall - haemopericardium; septum - left to right shunt (VSD); Papillary muscle - MR
How long after an MI does a ventricular aneurysm appear?
Over 4 weeks post MI
What Arrhythmia commonly presents after an MI? How long after an MI does it occur? What can it cause?
VF, usually occurs in the first 24hrs, common cause of sudden death
How many petients develop an arrhythmis following an MI?
90%
What are the pericardial complications of an MI?
Early (Peri-infarct associated) pericarditis, Pericardial effusion (+/- tamponade), Dressler’s Syndrome, Fibrinous Pericarditis#
What is Dressler’s syndrome? When and how does it present?
Secondary form of pericarditis due to cardiac injury; presents weeks-months after an MI with fever, pleuritic pain, pericarditis and/or a pericardial effusion.
When would fibrinous pericarditis be a complication of an MI? (what must occur during the MI?)
When the infarct extended to the epicardium
Histological findings post MI: under 6 hrs
Normal (CK-MB also normal)
Histological findings post MI: 6-24 hrs
Loss of nuclei, homogenous cytoplasm, necrotic cell death
Histological findings post MI: 1-4 days
Infiltration of polymorphs then macrophages (celaring up debris)
Histological findings post MI: 5-10 days
Removal of debris
Histological findings post MI: 1-2 weeks
Granulatioon tissue, new blood vessels, myofibroblasts, collagen synthesis
Histological findings post MI: weeks - months
Strengthening, decellularising scar tissue
What can be seen on histology of Early pericarditis?
Dusky haemorrhagic tissue
6 common causes of Heart Failure
Ischaemic heart disease, valve disease, myocarditis, hypertension, dilated cardiomyopathy, arrhythmias
Complications of Heart Failure
Sudden death, Systemic emboli, arrhythmias, deep vein thrombosis and PE, pulmonary oedema with superimposed infection, hepatic cirrhosis (nutmeg liver)
What system is activated when there is reduced cardiac output? What does this system then do? What complication does this cause in HF?
Renin-angiotensin system is activated
Renin -> AGT1 -> AGT2 -> Aldosterone -> salt and water retention; maintains perfusion, however overtime leads to fluid overload
What causes ventricular hypertrophy in HF? (Full mechanism, starts with decrese in SV)
Decresed Stroke Volume activatea the sympathetic NS via baroreceptors; prolonged activation –> increase in total peripheral resistance –> increased afterload –> ventricular hypertrophy
What causes ventricular dilatation in HF?
Increased afterload (due to high total peripheral resistance) –> increased EDV –> dilatation of the ventricle and worsening contractile function
What is seen macroscopically in HF?
LV is hypertrophied and dilated with myocardial fibrosis
What can result from the systemic effects of HF?
Pulmonary oedema, Hepatic cirrhosis (Nutmeg liver)
What is the crucial (exam key word) symptom of pulmonary oedema?
Cough producing a frothy pink transudate
What are the key symptoms of LV failure?
Damning of blood within the pulmonary circulation –> dyspnoea, orthopnoea, PND, wheeze, fatigue
What are the causes of RV Failure?
Chronic severe pulmonary HTN, or Secondary to LVF
Clincal Symptoms of RV Failure
Symptoms: peripheral oedema, ascites, facial engorgement
Investigations for ? RV Failure
BNP, CXR, ECG, Echo
Is nutmeg liver is assoicated with RV or LV Failure?
RVF
Pathology of RVF, pulmonary and systemically.
Engorgement of systemic and portal venous systems, minimal pulmonary congestion (unless caused by LVF)
What are the 3 patterns of cardiomyopathy?
Dilated, Hypertrophic, Restrictive
Which cardiomyopathy is associated with diastolic dysfunction and which with systolic dysfunction?
Dilated = Systolic dysfunction; Hypertrophic = Diastolic Dysfunctioon; Restrictive = Diastlic Dysfunction