Ischaemia & Infarction

Question 1

What are the commonest causes of coronary ischaemia

Answer 1

Coronary Arterial Atheroma
Pulmonary Oedema (usually due to LVF)
Heart Failure
Previous MI
Anaemia
Exertion/stress

Question 2

What causes stable angina vs unstable angina

Answer 2

Stable angina is most often caused by a coronary atheroma which occludes flow and so on exertion or stress when the demand increases the arteries cant meet it.
Unstable Angina (UAP) is caused by a complicated Atheroma with a growing thrombus, this grows over days or weeks causing the crescendo pattern of UAP.

Question 3

What are the three types of ischaemia?

Answer 3

Acute
Chronic
Acute-on-chronic

Question 4

What is the difference between ischaemia & infarction?

Answer 4

Infarction is a complete loss of blood supply leading to a build up of CO2 & Lactic Acid which causes necrosis.
Ischaemia is only partial and doesn’t involve necrosis

Question 5

What is repurfusion injury?

Answer 5

When circulation returns to an infarcted area the environment is so changed that the returning supply causes inflammation & oxidative damage which often further harms the tissue

Question 6

What are the two types of necrosis?

Answer 6

Coagulative - The structure remains in place for some time even as the tissue dies and is digested
Colliquative - The tissue is transformed into a liquid viscous mass

Question 7

What type of necrosis occurs in the heart due to infarction?

Answer 7

Coagulative

Question 8

Whats a transmural vs subendocardial MI?

Answer 8

A transmural MI affects the full thickness of the myocardium

A subendocardial MI is mainly limited to the myocardium just under the endocardial lining

Question 9

How do we distinguish Angina - UAP - NSTEMI - STEMI?

Answer 9

Angina - Pain on exertion, stable, stops on rest
UAP - Pain on increasingly little exertion (crescendo pattern)
NSTEMI - Elevated cTn (cardiac Troponin) levels indicates necrosis separating it from UAP
STEMI - ST elevation

Question 10

Name some possible complications of MIs and the 3 classes?

Answer 10

classes: Immediate - Early - Late

Complications:
Arrhythmia - Angina - Cardiac failure or rupture - Reinfarction - Pericarditis - DVT (with PE) - Mitral Incompetence - Papillary Muscle Dysfunction - Ventricular Aneurysm - Dressler’s Syndrome - Sudden Death