Coronary Heart Disease, Angina, MI and Embolism

Question 1

What conditions count as coronary artery disease?

Answer 1

Sudden cardiac death
Acute myocardial infarction 
Unstable angina 
Stable angina pectoris 
Heart failure 
Arrhythmia

Question 2

What two categories to patients presenting with sudden onset chest pain fall into?

Answer 2

Acute myocardial infarction

Progressive (unstable) angina

Question 3

How can coronary heart disease lead to sudden cardiac death

Answer 3

• coronary heart disease, lead to damage of the heart muscle leading to heart failure.
• if the damage to the heart muscle leads to scar tissue formation within the myocardium then this is an important substrate for the development of arrhythmia, which is the main substrate for sudden cardiac death

Question 4

How has the mortality from cardiovascular disease changed over the past 50 years?

Answer 4

It has decreased by 50%

Incidence of stable angina has increased

Question 5

Describe the division of the coronary resistance between the epicardial and intramyocardial vessels.

Answer 5

Normally, the resistance is divided 50:50 in the epicardial vessels and in the intramyocardial vessels

Question 6

Arterioles dilate in response to what?

Answer 6

Blood pressure - this is autoregulation

Question 7

What happens to the coronary vessels if there is epicardial stenosis?

Answer 7

The intramyocardial arteries can dilate to some extent to compensate for the increase in the epicardial vessels due to stenosis. The dilation of the intramyocardial arteries can maintain adequate blood flow to the tissues.

Question 8

At what point does coronary blood flow begin to change?

Answer 8

When stenosis exceeds 70%

Question 9

What is coronary flow reserve? What does it indicate?

Answer 9

Ratio of resting coronary blood flow to blood flow achieved under maximal stress.
Coronary flow reserve indicates the ability of the coronary circulation to adapt to increasing demand in the face of increasing epicardial stenosis.

Question 10

Describe angina pectoris?

Answer 10

Tight feeling in the chest that radiates to the jaw, shoulder, back or arms.

Question 11

What are anatomical tests in coronary artery disease used for?

Answer 11

Coronary artery angiograms - can be used to determine where the narrowing is

Question 12

What can be done to reduce myocardial oxygen demand following myocardial infarction?

Answer 12

Beta blockers to reduce the heart rate

Question 13

Describe what the differences are between a white thrombus and a red thrombus.

Answer 13

White thrombus is platelet rich and usually found in arterial thrombosis
Red thrombus is fibrin rich with trapped erythrocytes and is found in low pressure or venous situations

Question 14

Describe the changes in shear stress at a point of arterial stenosis.

Answer 14

The narrowing itself will have a very high shear stress.
The area distal of the narrowing will have low shear stress and so will promote endothelial dysfunction and accelerate atherogenesis.

Question 15

What can be made from the cellular constituents of atherosclerotic plaque that could trigger coagulation?

Answer 15

Tissue factor

Question 16

What is the main biochemical test for myocardial infarction?

Answer 16

Troponin

Question 17

What criteria define acute myocardial infarction?

Answer 17

A rise or fall in cardiac troponin exceeding the 99th percentile AND at least one of the following:
Symptoms suggestive of ischaemia
Pathological Q wave
New or presumed new ST-T changes or LBBB on ECG
Imaging evidence of new loss of viable myocardium
Identification of intracoronary thrombus or angiography or autopsy

Question 18

Which isoforms of cardiac troponin are specific to cardiac muscle and how long is it detectable for?

Answer 18

I and T

2 weeks

Question 19

What are the two types of acute coronary syndrome and what do the ECG changes show?

Answer 19

ST elevation - shows a complete occlusion in the coronary artery
NO ST elevation - could present as ST depression, inversion of the T wave or a normal ECG - shows partial occlusion that embolises distally into the microcirculation resulting in myocardial cell death and troponin elevation.

Question 20

What is PPCI?

Answer 20

Primary Percutaneous Coronary Intervention (or coronary angioplasty)
A catheter is passed into the coronary artery where the stenosis is and a balloon and stent is deployed to recanalise the vessel.

Question 21

Where does the myocardial necrosis zone start and how does it spread?

Answer 21

The myocardial necrosis zone starts in the inner part of the myocardium and then spreads outwards until it is transmural. The subendocardium is the work horse of the muscle and gets hit worst and first.

Question 22

What are the problems with reperfusing damage to the heart muscle?

Answer 22

The act of reperfusion itself may cause damage to the heart muscle.

Question 23

Describe adverse left ventricular remodelling and its consequences.

Answer 23

Adverse left ventricular remodelling involves thinning of the scar tissue, expansion of the heart muscle and impairment of heart function. This leads to increased risk of heart failure and arrhythmia. Dilation of the heart muscle (according to the Law of Laplace) means that there is increased wall tension. It causes reduced myocyte shortening, ventricular arrhythmias and ventricular fibrillation.

Question 24

Name two drugs that cause plaque stabilisation.

Answer 24

ACE inhibitors and statins

Question 25

Name four types of embolism other than a thromboembolism.

Answer 25

Air, Fat, Tumour, Amniotic Fluid