Cardiovascular disorders

Question 1

What are some cardiovascular disorders?

Answer 1

Cardiovascular disease, Coronary heart disease, Heart failure and hypertension.

Question 2

What is CVD?

Answer 2

Describes what is known as atherosclerosis. This affects arteries in the brain, lung and peripheral tissue.

Atherosclerosis

• deposition of lipid and matrix protein in the arterial wall
• narrowing of the vessel lumen
• reduced blood supply
• heart - causes coronary heart disease
• brain - causes stroke

Question 3

How can atherosclerosis cause artery narrowing?

Answer 3

Begins with deposition of lipids on the innerlining of the vessel causing an inflammatory response.

Macrophages and monocytes migrate to the area and attack the lipid cells causing generation of cytokines. Cytokines begin to destroy the elastic lamina of the vessel
- Smooth muscle cells migrate to the lumen and cover the lipids. They begin to secrete collagen and other ECM proteins resulting in endothelial cells growing on top of the lipid cap

The lipid cap is now part of the inner surface of the artery, causing narrowing of the artery.

Question 4

What are the consequences of atherosclerosis?

Answer 4

Coronary heart disease. Failure of coronary circulation to meet demands of the heart.

Can also be caused by cardiovascular disease (coronary arterial disease) vasospasm, anaemia, arrhytmias

CHD is sometimes referred to as ischaemic heart disease.

Question 5

What is the result of CHD/CAD?

Answer 5

CHD causes myocardial infarction (aka heart attack), due to prolonged ischaemia which induces necrosis.

MI may also get collagen scarring.
Most likely a result of CAD

Question 6

What is coronary artery disease (CAD)?

Answer 6

Atherosclerosis in coronary arteries causing inadequate oxygen supply to the heart. Leads to stable angina and acute coronary syndrome

Question 7

What is acute coronary syndrome (ACS)?

Answer 7

Describes a spectrum of disorders due to plaque rupture. The plaque rupture due to overcapacity of lipid cap, and the narrowed lumen eventually is blocked by a blood clot at site which further cause occlusion.

Caused by unstable angina or MI.

Question 8

What causes a fibrous cap to burst?

Answer 8

Combination of mechanical stress on fibrous cap and weakening of the fibrous cap ECM leads to rupture.

Question 9

What are some key biochemical markers of ACS?

Answer 9

Cardiac enzymes, myoglobin and troponins

Question 10

What cardiac enzymes indicate ACS?

Answer 10

alanine aminotransferase (ALT), Aspartate aminotransferase (AST) , Creatinine Kinase (CK), Lactate dehydrogenase (LDH), myoglobin

Question 11

What is the most commonly used marker (ACS) and why?

Answer 11

The troponins are the most widely used marker of ACS, due to their great specificity and sensitivity compared to the cardiac enzymes which are not specific to the heart.

Thus high sensitive assays of TnT or TnI are used - because of their lowered detection limits

Question 12

What is the clinical implications of using troponin T or I as marker for ACS?

Answer 12

Both are markers for cardiac damage. Troponin I is more specific, because skeletal troponin T isoforms cross react in cardiac troponin T assays.

Question 13

Difference between the 3 troponin proteins?

Answer 13

T - binds to tropomyoisn
I - inhibitor of ATPase
C - Binds calcium

All act on sacromeres to reduce contractility.

Question 14

What does detection of ACS markers depend on and can you give examples?

Answer 14

Depends on: size, cellular location, plasma clearance.

Myoglobin rises significantly in the first day, but is also cleared after the first day.

LDH doesnt reach its peak till day 3, but resides for more than a week from onset.

Question 15

Define MI using WHO definition.

Answer 15

Detection of rise and/or fall of cardiac biomarkers (preferably)with at least one value above the 99th percentile of the upper reference limit.

Question 16

What is heart failure? What is the cause?

Answer 16

Failure of the heart output to meet demand (of rest of body) - compared to CHD where the heart fails to meet its own oxygen demand.

Caused by: cardiomyopathy, inflammation, valvular heart disease, ischaemic heart disease (CHD)

Question 17

What happens if the heart is not functioning properly?

Answer 17

If the heart is not pumping properly then you get backpressure to the rest of the body. This force fluid out of the blood into the interstitial space causing oedema

• Failure of right side: Receives blood on the right side from the superior vena cava. Failure results in back pressure back into the superior vena cava, which causes oedema and swelling of the abdomin
• Failure of the left side: Which receives blood from the lungs. Failure results in backpressure through to the lungs causing the fluid to move out of the veins and aorta – causes pulmonary oedema (excess fluid in lungs)

Question 18

How do you diagnose HF?

Answer 18

Echocardiogram or brain natriuretic peptide (BNP).

Question 19

Describe BNP and its clinical significance for assessing HF.

Answer 19

It is a natriuretic peptide secreted primarly from ventricles as a prohormone (proBNP).

In cardiac failure due to the heart overworking, it causes the ventricels to become stretched and release BNP + proBNP. Immunoassays are available for both BNP and NT-proBNP. Generally proBNP is better due to its stability and longer half life.

BNP assays are useful ruleout tests - referral to echocardiogram

Question 20

BNP is increased by…..

Answer 20

Ventricular hypertrophy, ischaemic tachycardia, sepsis, COPD, hypoxaemia, renal disease – also age is a factor

Question 21

BP of > 140/90mmHg describes what condition

Answer 21

Hypertension

Question 22

What are some risk factors of hypertension?

Answer 22

CVD, CHD and stroke

Question 23

Conns, cushing and phaeochromocytoma can cause ..?

Answer 23

endocrine hypertension