Module 4 Part 1 - Cardiovascular Pathology

Question 1

Atherosclerosis

Answer 1

The thickening or hardening of 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 and fibrotic tissue and cells, including inflammatory cells

Question 2

Oxidative Modification Hypothesis

Answer 2

LDL is modified (oxidised) which is then preferentially taken up by scavenger receptors to form foam cells and ultimately fatty lesions and plaques

Question 3

Cardiac Consequences of Atherosclerosis

Answer 3

Angina - chest pain
- stable = in response with exertion
- unstable = without exertion
Acute myocardial infarction - plaque build up in coronary vessels
Heart failure - the heart loses its effectiveness to pump

Question 4

Blood Vessels Affected by Atherosclerosis

Answer 4

Many blood vessels can be affected
Most important are aorta, coronary and those feeding into the brain
Smaller vessels in the periphery can also be affected
Hard to detect as requires removal of vessel to confirm presence
- ultrasound - can detect plaque build up
- angiography - x-ray imaging of vessels using contrast agents injected into femoral artery

Question 5

Examples of Treatments for Atherosclerosis

Answer 5

Angioplasty - insertion of balloon to widen vessel walls
Stents - plastic ‘vessel’ to maintain vessel width
Coronary artery bypass graft (CABG) - vessels re-routed around the blockage
Drugs to lower BP and cholesterol
Nitroglycerin - dilates vessels
Blood thinners, aspirin and anticoagulants

Question 6

Unstable Angina

Answer 6

Chest pain due to poor blood flow and oxygen to heart
- without treatment can lead to heart attack
In most cases the angina is due to a narrowing of the blood vessels supplying the heart
Its not a disease but a symptom of 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

Question 7

Acute Myocardial Infarction

Answer 7

Acute myocardial infarction occurs when blood flow stops to a part of the heart and causes damage to the heart muscle
Without treatment the damage can be permanent
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:
- ECG - monitors electrical impulses from your heart
- blood tests - heart muscle dies and releases proteins into the bloodstream (cardiac enzymes - creatine kinase & troponin)
- chest x-ray
- angiogram

Question 8

Heart Failure

Answer 8

AMI results in necrosis of myocardial tissue
If substantial, this will impair the ability to pump blood and may lead to heart failure
Decreased blood flow:
- can results in shock
- usually happens in context of severe AMI
- can affect brain, heart, kidney, liver
Back pressure in some tissues/organs:
- cant pump the blood out
- blood can back up
- organ affected depends on which part of the heart is most affected
- most common is left side -> pulmonary edema

Question 9

Tests for Heart Failure

Answer 9

Brain natriuretic peptide - peptide hormone stored mainly in myocardium of ventricles and levels increase in response to stretching of myocardium (atrial or ventricular) and increased in all forms of fluid overload stretching of myocardium
Renal actions - stimulates excretion of sodium

Question 10

Complications of Heart Failure

Answer 10

Kidney damage and failure
- from reduced blood flow
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 edema
- back pressure

Question 11

Pulmonary Edema

Answer 11

Caused by back pressure
Fluid shifts from capillaries into the alveoli or air sacs
Leads to decreased gas exchange

Question 12

Other Diseases of the Heart

Answer 12

Examples of causation of cardiac myopathy (disease of the heart muscle that makes it harder for your heart to pump blood to the rest of your body):
- thyroid disease
- hemochromatosis
- muscular dystrophy
- myocarditis due to infectious agents
Conditions which make the heart work harder are risk factors for heart failure
- high blood pressure
- kidney disease (because there can be fluid retention)
- type 2 diabetes
- overweight