CVS 19 - CHD, angina,MI, 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 has the mortality from cardiovascular disease changed over the past 50 years?

Answer 3

It has decreased by 50%

Incidence of stable angina has increased

Question 4

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

Answer 4

Normally, the resistance is divided 50:50 in the epicardial vessels and in the intramyocardial vessels. However in diseased heart you have greater resistance in epicardial vessels (because of stenosis).

Question 5

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

Answer 5

The intramyocardial arteries can dilate to some extent to compensate for the increase in the epicardial vessels due to stenosis (until 70% stenosis). The dilation of the intramyocardial arteries can maintain adequate blood flow to the tissues.

Question 6

What is coronary flow reserve? What does it indicate?

Answer 6

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 7

Describe angina pectoris?

Answer 7

Tight feeling in the chest that radiates to the jaw, shoulder, back or arms. Provoked by exertion or emotional stress.

Question 8

What investigations can be done for CHD?

Answer 8

Non-invasive: Exercise ECG, stress echo, CT angiogram

Invasive: Coronary angiogram

Question 9

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

Answer 9

Reduce HR - beta blockers, Ca antagonists
Wall stress - ACE inhibitors
Metabolic modifiers

Can also do lifestyle modification, increase blood flow

Question 10

How is blood flow interrupted to the heart? (3 mechanisms)

Answer 10

• Coronary plaque rupture (70-80% of thrombosis)
• Coronary plaque erosion (20-30%)
• Coronary dissection

Question 11

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

Answer 11

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 12

What criteria define acute myocardial infarction?

Answer 12

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 13

What is the main biochemical test for myocardial infarction?

Answer 13

Troponin

Question 14

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

Answer 14

Tissue factor

Question 15

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

Answer 15

I and T

2 weeks

Question 16

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

Answer 16

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 17

What is PPCI?

Answer 17

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 18

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

Answer 18

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 19

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

Answer 19

The act of reperfusion itself may cause damage to the heart muscle. If you reperfuse + cardioprotection you can prevent lethal reperfusion injury.

Question 20

Describe adverse left ventricular remodelling and its consequences.

Answer 20

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 21

Name two drugs that cause plaque stabilisation.

Answer 21

Statins

ACE inhibitors

Question 22

Name four types of embolism other than a thromboembolism.

Answer 22

Air, Fat, Tumour, Amniotic Fluid

Question 23

How is thrombotic risk managed?

Answer 23

Antiplatelets (aspirin), anticoagulants, thrombectomy

Question 24

What are the two types of tests used to investigate ischaemic heart disease?

Answer 24

Functional and anatomical