Ischemic Heart Disease and Hypoxia

Question 1

Define IHD

Answer 1

The term given to heart problems caused by narrowed heart (coronary) arteries that supply blood to the heart muscle

Question 2

What is there a mismatch between in IHD

Answer 2

Demand and supply of oxygen

Question 3

What are other names for IHD?

Answer 3

Coronary artery disease (CAD)

Coronary heart disease (CHD)

Question 4

What are the 2 ways IHD manifests clinically?

Answer 4

Myocardial infarction

Ischemic cardiomyopathy

Question 5

What is a reason the prevalence of IHD has increased over time?

Answer 5

Life expectancy has gone up and its more common in the older population

Question 6

Why does sudden death occur in IHD?

Answer 6

Due to occlusion of arteries

Question 7

What are the main signs and symptoms of IHD?

Answer 7

Angina/chest pain
Heart rhythm problems
Nausea, sweating, fatigue or shortness of breath, weakness or dizziness
Reduced exertional capacity
Leg swelling (when left ventricular dysfunction is present)
Diaphoresis (increased sweating)

Question 8

When does leg swelling occur in IHD?

Answer 8

When left ventricular dysfunction is present

Question 9

How does angina manifest?

Answer 9

Aching, burning, fullness, heaviness, numbness, pressure, squeezing
Radiation in arms (usually left but also can be right), back, jaw, neck, shoulder
High or low BP
Syncope

Question 10

What is angina often mistaken for? When does this especially happen?

Answer 10

Indigestion or heart burn, especially if the pain doesn’t radiate and localised to the centre of the chest

Question 11

How do heart rhythm problems manifest in IHD?

Answer 11

Palpitations 
Heart murmurs
Tachycardia 
Atrial fibrillation
Ventricular tachycardia or ventricular fibrillation

Question 12

What is S3 and S4 gallop?

Answer 12

They are sounds heard that indicate left ventricular dysfunction, S3 is heard after the mitral valve opens as blood pours into the left ventricle

Question 13

What is diaphoresis?

Answer 13

Increased sweating

Question 14

What are non modifiable risk factors for IHD?

Answer 14

Age 
Gender (more common in males)
Family history
Ethnicity
Genetics (eg hypercholesterolaemia)
Past history of CVD

Question 15

What are modifiable risk factors for IHD?

Answer 15

BP
Cholesterol
Smoking
Diabetes
BMI
Diet (this is the biggest risk factor)
Inactivity
Stress/mental health
Low social economic state
Alcohol
Income
Social deprivation
Environment
Some medications

Question 16

What are the 2 main causes of IHD?

Answer 16

Reduced coronary blood flow to a region due to obstruction

General decrease of oxygenated blood flow

Question 17

What are some causes of obstruction causing reduced coronary blood flow?

Answer 17

Atheroma
Thrombosis
Spasm
Embolus
Coronary ostial stenosis
Coronary arteritis

Question 18

What are some causes of decreased flow of oxygenated blood?

Answer 18

Anaemia Carboxyhaemoglobulinaemia

Hypotension

Question 19

What is the process by which an atherosclerotic plaque forms called?

Answer 19

Atherogenesis

Question 20

What are some triggers for atherogenesis?

Answer 20

Endothelial dysfunction
Mechanical sheer stresses (HTN)
Biochemical abnormalities (elevated and modified LDL, DM, elevated plasma homocysteine)
Immunological factors (free radicals from smoking)
Inflammation (infection such as chlamydia, Helicobacter)
Genetic alteration

Question 21

Describe a stable plaque

Answer 21

Fibrous cap of layers of VSMC surrounded by ECM network which is an effective barrier preventing rupture
They have a small necrotic core

Question 22

Describe a vulnerbale plaque

Answer 22

Unresolved inflammation causes thinning of the fibrous cap
Areas where thinning has occurred are prone to rupture, if this happens there is thrombus formation and this leads to clinical events

Question 23

What are the 5 ways IHD may present

Answer 23

Asymptomatic 
Chronic stable angina
Acute coronary syndromes (unstable angina, non ST elevation MI or ST elevation MI
Heart failure 
Sudden death

Question 24

Once an atherosclerotic plaque has contact with flowing blood what happens?

Answer 24

Platelets can adhere to it
Fibrin is deposited
RBCs get trapped and a clot forms

Question 25

How does hypoxia arise as a result of atherosclerosis?

Answer 25

Once the atherosclerotic plaque breaks through the endothelium and forms a clot, the clot can occlude a vessel

Question 26

What is a coronary embolus?

Answer 26

When the clot formed by a ruptures atherosclerotic plaque breaks away and blocks a more distal artery

Question 27

What is a collateral?

Answer 27

When small arteries anastomose together

Question 28

What happens to collaterals in an acute episode?

Answer 28

They dilate within seconds and can double by the second or third day

Question 29

How do collaterals develop in chronic atherosclerotic patients?

Answer 29

Slowly as the atherosclerosis gets worse

Question 30

Why does ACS still occur even though collaterals exist?

Answer 30

Extensive atherosclerosis can damage the collaterals themselves, also if they get too big they may not be able to maintain blood supply

Question 31

Is full recovery post MI possible?

Answer 31

Yes, in about a month its possible

Question 32

How does infraction occur?

Answer 32

After occlusion there is no flow or very little flow to the muscle so function cannot be sustained

Question 33

What occurs to muscle after infraction?

Answer 33

Small amount of collaterals open and blood seep into the infarcted area Local blood vessels dilate, and area becomes overfilled with stagnant blood Muscle fibres use all the remaining oxygen, haemoglobin becomes totally deoxygenated giving bluish brown hue & blood vessels appear engorged despite lack of blood flow

Question 34

How much oxygen do cardiac muscle cells need?

Answer 34

1.3ml of oxygen per 100ml of tissue

Question 35

How much blood supply is required to stop cardiac muscle from dying?

Answer 35

15-30%

Question 36

What are causes of death after MI?

Answer 36

Decreased cardiac output Ventricular fibrillations Rupture of infarcted area Damming of blood in the venous system

Question 37

What is systolic stretch?

Answer 37

When there is dead muscle after MI, it is pulled on in systole and when it stretched it can become balloon shaped

Question 38

How may the heart be damaged further after MI?

Answer 38

If there is excess exertion damage may occur as the heart has reduced reserve

Question 39

How is risk of MI calculated?

Answer 39

JBS3 is used in GPs | Q risk is used in hospitals

Question 40

What clinical examinations are done when diagnosing MI?

Answer 40

Heart auscultations BP BMI GPE

Question 41

What lab tests are done when diagnosing MI?

Answer 41

``` LDL HDL Triglycerides Lipoprotein A C reactive protein ```

Question 42

What are the serum markers in patients with suspected acute cardiac events?

Answer 42

Troponins (I or T) Creatine kinase with MB isozymes Lactate dehydrogenase and lactate dehydrogenase isozymes Serum aspartate aminotransferase

Question 43

What are biomarkers for predicting death?

Answer 43

``` B-type natriuretic peptide CRP Homocysteine Renin Urinary albumin-to-creatinine ratio ```

Question 44

What is seen on an ECG for stable angina?

Answer 44

Pretty much normal | If you want to see the changes do an exercise stress test, during stress test might see ST depressions indicating

Question 45

What is seen on an ECG for unstable/NSTEMI angina?

Answer 45

ST depressions and T wave inversion

Question 46

What is seen on an ECG for acute MI/STEMI angina?

Answer 46

ST segment elevation with T wave inversion, Q waves

Question 47

What is transthoracic ECG used for?

Answer 47

Assess left ventricular function Wall-motion abnormalities in ACS or AMI Mechanical complications of AMI

Question 48

What is transoesophageal ECG used for?

Answer 48

Assessing possible aortic dissection in the setting of AMI

Question 49

What is stress ECG used for?

Answer 49

To evaluate hemodynamically significant stenosis in stable patients who are thought to have CAD

Question 50

What is coronary angiography used for?

Answer 50

In vivo assessment of coronary arteries

Question 51

How do HMG CoA reductase inhibitors work?

Answer 51

They lower LDL-C levels and triglyceride levels Raise serum HDL levels

Question 52

How do bile acid sequestrates work?

Answer 52

Block enterohepatic circulation of bile acids and increase the fecal loss of cholesterol

Question 53

How do CCBs work?

Answer 53

Relaxes coronary smooth muscle and produces coronary vasodilation to increase oxygen delivery to the heart

Question 54

How do ACE inhibitors work?

Answer 54

Hypertension and atherosclerosis may be intimately linked through their effects on vascular endothelial dysfunction so they can help

Question 55

How do beta blockers work?

Answer 55

Inhibit sympathetic stimulation of the heart, reducing heart rate and contractility; this can decrease myocardial oxygen demand and thus prevent or relieve angina in patients with CAD

Question 56

How do antianginal agents work?

Answer 56

Reduces myocardial cellular sodium and calcium overload via inhibition of the late sodium current of the cardiac action potential

Question 57

How do platelet aggregate inhibitors work?

Answer 57

Exert protection against atherosclerosis through inhibition of platelet function and through changes in the hemorrhagic profile

Question 58

How do nitrates work?

Answer 58

They decrease myocardial oxygen demand by producing systemic vasodilation

Question 59

What are the 2 main revascularisation therapies?

Answer 59

Percutaneous coronary intervention | CABG

Question 60

How does percutaneous coronary intervention work?

Answer 60

Angiography and stent placement helps improve blood flow

Question 61

When is percutaneous coronary intervention used?

Answer 61

To treat stable CAD

Question 62

How does CABG work?

Answer 62

A vessel from another part of your body to create a graft that allows blood to flow around the blocked or narrowed coronary artery

Question 63

When is CABG performed?

Answer 63

In people who have several narrowed coronary arteries

Question 64

What are some preventative measures for IHD and MI

Answer 64

``` Do physical activity Stop smoking Healthy diet Reduce weight if overweight Reduce stress at home and work ```

Question 65

What do Q risk and JBS3 show?

Answer 65

Risk of MI in the next 10 years