L12 - Cardiovascular Pathology Flashcards
Cardiovascular Disease
- CVD is the leading cause of death & disability in the world
- Characterised by disease that involves the heart and/or blood vessels
– Hypertension – Myocardial infarction – Atherosclerosis – Stroke (ischaemic& hemorrhagic) – Coronary artery disease (CAD) – Peripheral Vascular Disease (PVD)
Risk factors for CVD
• Genetic & lifestyle
– High blood pressure – High cholesterol – Overweight/obese – Physical inactive – Smoking – Diet low in fruits & vegetables – Excessive alcohol consumption
etc.
Atherosclerosis
- Atherosclerosis is thickening or hardening of the arteries
- Gradual progression that begins in early childhood
- Leads to the formation of an atheroma; accumulation of lipid in the intima of a blood vessel
- Finally have formation of plaque; lesion comprised of lipid, connective & fibrotic tissue and cells, including inflammatory cells
Lipid accumulation and atherosclerosis
- Lipid accumulation does not occur through the LDL-receptor pathway
- FH patients; defects in their LDL receptor, but still have high incidence of CVD
- Oxidative modification hypothesis; LDL is modified (oxidised) which is then preferentially taken up by the scavenger receptors to form foam cells and ultimately fatty lesions and plaques
- Additional recruitment of monocytes, which turn to macrophages, adds to the process
Cardiac consequences of atherosclerosis
• Angina (chest pain)
– Stable; in response to exertion
– Unstable; without exertion
- Acute myocardial infarction (plaque build up in coronary vessels)
- Heart Failure (the heart loses its effectiveness as a pump)
Blood vessels affected by atherosclerosis
- Many blood vessels can be affected by atherosclerosis
- The most important are aorta, coronary and those feeding the brain
- Smaller vessels in the periphery (peripheral vascular disease) can also be affected.
• Hard to detect as requires removal of vessel to confirm presence
– Ultrasound»_space; carotid & brachial»_space; can detect plaque build-up»_space;often at advanced stage
– Angiography»_space; x-ray imaging of vessels using contrast agents injected into femoral artery
Treatments to blood vessels after atherosclerosis
– Angioplasty: insertion of a balloon to widen vessel walls
– Stents: plastic “vessel” to maintain vessel width
– Coronary artery bypass graft (CABG): vessels are re-routed around the blockage
– Drugs to lower BP and cholesterol
– Nitroglycerin: dilates vessels
– Blood thinners, aspirin & anticoagulants
Unstable angina
- Chest pain due to poor blood flow and oxygen to the heart; without treatment can lead to a heart attack.
- In most cases the angina is due to a narrowing of the blood vessels supplying the heart
- It’s not a disease but a symptom of an underlying heart problem
- Stable angina (prompted by exercise) is due to the increased workload of the heart. Usually disappears with rest.
• Symptoms
– pain, pressure and tightness in the chest. Can feel like indigestion
• Similar tests to that of AMI (often treated the same), but may also include a stress test
Acute Myocardial Infarction
- Occurs when blood flow stops to a part of the heart and causes damage (infarction) to the heart muscle (myocardium)
- Usually begins when a plaque cracks and additional RBCs build up and adhere to the damaged plaque, leading to a complete blockage of the vessel. If the blockage remains, the loss of blood flow to that part of the heart results in damage and possible tissue necrosis
Diagnosis of AMI
– ECG (monitors the electrical impulses from your heart)
– Blood tests (heart muscle dies and releases proteins into the blood stream; cardiac enzymes)
– Chest x-ray
– Angiogram
Heart failure
- AMI results in necrosis of myocardial tissue
- If substantial, this will impair the ability to pump blood & may lead to heart failure, which can affect a number of tissues & organs
- Decreased blood flow (Can result in shock, Usually happens after severe AMI Can affect brain, heart itself, kidney, liver etc.)
- Backpressure in some tissues/organs: blood can’t be pumped out, blood backs up in lungs (may cause SOB) and other organs
- Organ affected depends on which part of heart is most affected.
- Most common is left side > pulmonary oedema
Tests For Heart Failure
- Brain natriuretic peptide (BNP), stored mainly in myocardium of ventricles
- Peptide hormone, levels increase in response to stretching of myocardium (atrial or ventricular) and increased in all forms of fluid overload (e.g. Conn’s, Cushing’s).
- Renal actions: stimulates excretion of sodium
• Clinical Utility
– HF difficult to diagnose. – Numerous other disorders can present with similar signs.
• Useful to differentiate pulmonary vs cardiac cause for shortness of breath.
Complications of Heart Failure
• Kidney damage or failure.
– From Reduced blood flow. Will cause kidney failure if untreated.
• Heart valve problems. – From blood and fluid buildup.
• Liver damage.
– Back pressure. Damaging.
• Heart attack and stroke.
– From thrombosis or clot formation. Reduced blood flow in the heart increases likelihood of blood clot formation.
• Pulmonary Oedema
– Backpressure.
Pulmonary Oedema
- Backpressure
- Fluid shifts from capillaries into the alveoli or air sacs.
- Decreased gas exchange.
Other diseases of the heart
- “Heart Disease” is usually referred to as artery disease (CAD).
- Other examples for cardiac myopathies:
- Thyroid disease
- hemochromatosis
- muscular dystrophy
- myocarditis due to infectious agents (e.g. influenza, Epstein-Barr virus)
