Session 10 - Ischaemic Heart Disease and Chest Pain Flashcards
Describe the structure of atheromas in stable angina?
Atheromatous plaques with a necrotic centre and fibrous cap
What is the effect of atheroma in IHD?
Occlude more and more of the lumen as they build up in coronary vessels. This leaves less space for passage of blood and ischaemia in myocardium
At what point does an atheromatous plaque cause angina?
When it occludes more than 70% of the lumen
What occurs in stable angina?
Brief episode of ischaemia pain brought on by stress.
Predictable pain, relieved by rest or nitrates within five minutes.
Presence of risk factors
What is brief chest pain in ischaemic heart disease typically caused by? How is it described?
brought on by exertion, emotion particularly after meals and in cold weather. It is described as mild to moderate pain.
What is the treatment of
acute episodes of angina
preventative episodes of angina
Preventative - B blockers, Ca2+ channel blockers, oral nitrates
Prevent cardiac events- Aspirin, statins, ACE inhibitors
Long term - consider revascularisation
In basic terms, what is the use of Nitrates Ca2+ blocker ACE inhibitors Beta blockers In stable angina
Nitrates - decreased preload, venodilation
Ca2+ blocker - decreased after load, peripheral vasodilation
ACE inhibitors - reduced after load
Beta blockers - Reduced HR and contractility
How does unstable angina form?
Develops from stable angina, due to increased occlusion of lumen
Define unstable angina
Ischaemic Chest Pain that occurs at rest (or with minimal exertion) described as severe pain and occurring with a crescendo pattern (distinctly more severe, prolonged, or frequent than before)
Define MI
A MI is a complete occlusion of a coronary vessel, leading to an infarct (death) of the myocardium it supplies.
What can happen to an atheroma to form a thrombosis which will occlude a vessel?
The fibrous cap of the Atheromatous plaque can undergo erosion or fissure, exposing blood to the thombogenic material in the necrotic core.The platelet ‘clot’ is followed by a fibrin thrombus, which can either occlude the entire vessel where it forms or break off to form an embolism.
How does MI present?
MI presents with typical ischaemic chest pain that is very severe, persistent, at rest and often with no precipitant. It is not relieved by rest or nitrate spray. The patient may also be breathless, faint, feeling of impending doom and autonomic features.
Describe the autonomic features of an MI (adrenaline)
Sweating, pallor, nausea and vomiting
What is an NSTEMI
Non ST Elevated Myocardial Infarction
Infarct is not full thickness of myocardium
What is a STEMI
ST Elevated Myocardial Infarction
Infarct is full thickness of myocardium
What is the clinical diagnosis of angina based on ?
History
What are the four risk factors for angina which can be revealed from a cardiovascular exam?
Elevated BP
Corneal arcus
LV dysfunction
Signs of peripheral vascular disease
What is the resting ECG of someone with stable angina usually like?
Normal, but may show signs of previous MI (pathological Q wave)
How do you confirm stable angina if a resting ECG is normal?
Exercise stress test
What is an exercise stress test? How long does it go on for?
Graded exercise on a treatment connected to an ECG until: Target heart rate reached OR Chest Pain OR ECG changes OR Other problems – arrhythmias, low BP etc…
QUESTION What is a positive ECG after exercise stress test for stable angina?
Why do you get st depression, cell death?
Shows ST depressions of >1mm. A strong positive test indicates critical stenosis
What is acute coronary syndrome? What is it a result of?
Acute Coronary Syndrome (ACS) relates to a group of symptoms attributed to the obstruction of the coronary arteries. ACS is a result of:
Unstable Angina
NSTEMI
STEMI
Describe unstable angina Occlusion by thrombosis? Myocardial necrosis? ECG character? Biochemical blood markers?
Occlusion by thrombosis? Partial Myocardial necrosis? None ECG character? May have ST segment depression, T wave inversion or normal Biochemical blood markers? None
Describe NSTEMI Occlusion by thrombosis? Myocardial necrosis? ECG character? Biochemical blood markers?
Occlusion by thrombosis? Partial Myocardial necrosis? Some ECG character? No ST segment elevation Biochemical blood markers? Troponin