Ischaemic Heart Disease

Question 1

Aetiology

Answer 1

Genetic infection
Alcohol
Cocaine

Question 2

Cause of Ischaemic heart disease

Answer 2

Decreased O2 supply- blocked coronary artery- also, lack of blood flow allows a build up of waste products (lactic acid) or accumulation of electrolytes causing injury to tissue.

Increased O2 demand- stress, exercise

Most common causes are:
atherosclerosis
thrombosis- thrombus is built/ fixed.

Question 3

Pathogenesis

Answer 3

Atheroma and thrombus

• vasospasm of coronary artery: loss of vasodilators, platelet aggregation eg micro-thrombus forms on the artery wall, platelets release TXA2, causing vasoconstriction and activation of more platelets. Vasospasm can occur on arteries with or without significant atheroma.
• blood flow is constricted during an artery spasm- found most obstructions were in proximal parts of RIght coronary artery, LEft ascending d and circumflex arteries. Left hand arteries most common.
• thrombus is fixed, it is built into the wall of the artery, not travelling (embolus)

Question 4

Clinical effects of IHD: angina

Answer 4

Angina- pain.

• stable- typical, predictable, bought on by exercise, stress and is relieved by decreased exercise
• unstable- unpredictable, progressive increases in frequency, intensity, caused by thrombosis or vasospasm in a coronary artery.
• variant

Question 5

Type of heart disease

Answer 5

Congenital heart disease 
Rheumatic heart disease 
Endocarditis
Cardiomyopathy 
Myocarditis

Question 6

Clinical effects of IHD: Myocardial Infarct

Answer 6

If somebody doesn’t survive myocardial Infarct it’s called sudden cardiac death.
Assume they survived, complication:
- rupture of ventricular wall. Generally occurs in first two weeks. Loss of blood in the pericardial sac, leads to a decrease in cardiac output and a drop in blood pressure.
- rupture leads to blood in pericardial sac- pressure against heart, reducing cardiac output (cardiac tamponade: when there is fluid in pericardial sac). Pressure against venous return.
- mitral incompetence: infarction may cause damage to papillary muscles causing failure of AV valves to close properly.
- thrombosis formation. Fine until it travels (thrombosis embolism).
- ventricular aneurysm: decreased cardiac output. Thrombosis/ embolism formation.
- arrhythmia-

Question 7

Clinical effects of IHD: Sudden cardiac death

Answer 7

Death within 24 hours of the CV event- most die in first 6 hours.
Causes:
- congenital malformations- hypertrophic cardiomyopathy
- commotio cordis (myocardial concussion), chest trauma
- coronary (Ischaemic) artery disease
speed and location of obstruction- history of obstruction may allow people to quickly form new blood vessels
location and extent of infarction- effects range from subclinical, to AMI, to fatal arrhythmia (ventricular fibrillation- quivering of ventricles)

Question 8

Acute coronary syndrome

Answer 8

• unstable angina
• acute myocardial Infarct
• sudden cardiac death
  Caused by erosion or rupture of the plaque, followed by thrombosis or vasospasm of the artery

Question 9

Clinical effects of IHD: chronic ischaemic heart disease

Answer 9

Leads to left or right heart failure.
Left heart failure:
-Left ventricular Hypertrophy- from hypertension, or from Hypertrophy of surviving fibres
-Left ventricular dilatation- decreased contraction force, heart failure
- congestive heart failure- decrease in cardiac output m, congestion, oedema
Right heart failure:
- pulmonary hypertension
- ischaemic heart disease
- valve disease
- right ventricular failure- Hypertrophy then dilatation. Congestion and oedema.

Question 10

Risk factors for IHD

Answer 10

Disease development:

• risk factors for atherosclerosis (long term factors) - fatty streak, occurs at bends and bifurcations, and increased inflammatory mediators in the plasma
• risk factors for thrombosis (short term risks)

Sudden events
- risk factors for unstable angina, AMI, and sudden cardiac death. Usually caused by rupture of an atheroma, and thrombosis

Unchangeable:

• age
• gender
• genetic factors

Modifiable:

• hypertension, risk factors for hypertension all risk factors for CVD-damage to arterial wall, high sodium intake, binge drinking, genetics
• high blood cholesterol
• diabetes
• smoking - stable angina, unstable angina, AMI, stroke, peripheral vascular disease, chemical injury to vessel wall, inflammation in vascular endothelial cells, increases platelet aggregation and adhesion
• binge drinking
• stress - leads to AMI, sudden death, stroke