Ischaemic Heart Disease Flashcards
What is the definition of Ischaemic Heart Disease?
Characterized by reduced blood supply (ischaemia) to the heart muscle resulting in chest pain (angina pectoris). May present as ‘stable angina’ or ‘acute coronary syndrome’
(ACS).
How could ACS be further subdivided?
ACS can be further subdivided into unstable angina (no cardiac injury), non-ST-elevation myocardial infarction (NSTEMI) or ST-elevation MI (STEMI, transmural infarction). MI refers to cardiac muscle necrosis resulting from ischaemia.
Describe the pathogenesis of ischaemic heart disease?
Development of atheroma is key pathological process in ischaemic heart disease. Atheroma is characterised by the formation of atherosclerotic plaques which consist of a cholesterol core surrounded by smooth muscle cells.
Ulceration on the surface of plaques can lead to intense platelet aggregation and thrombus formation.
Leads to complete arterial occlusion.
In their stable state athermatous plaques reduce lumen diameter and blood flow.
If atheroma occurs in the lumen of coronary arteries cardiac muscle can become ischaemic.
Myocardial infarction will occur is blood supply is completely lost.
Describe modifiable and non modifiable risk factors for ischaemic heart disease.
Modifiable risk factors in the development of ischaemic heart disease include smoking, hyperlipidaemia, hypertension and good glycemic control in diab mellitus patients.
Non modifiable risk factors include increasing age, family history of ischaemic heart disease, in a first degree relative aged
Describe the pathogenesis of atherosclerosis.
Endothelial injury is followed by migration of monocytes into sub endothelial space and differentiation into macrophages. Macrophages accumulate LDL lipids insudated in the subendothelium and become foam cells. They release growth factors, which stimulate smooth muscle proliferation, production of collagen and proteoglycans.
This leads to the formation of an atheromatous plaque
List risk factors of developing ischaemic heart disease.
Male Diabetes mellitus FHx Hypertension Hyperlipidaemia Smoking Previous history
What would a patient with ischaemic heart disease describe in their history?
cheast pain or discomfort of acute onset.
Central heavy tight “gripping” pain that radiates to arms (usually L), neck, jaw or epigastrium.
May be associated with breathlessness, sweating, nausea and vomiting.
Stable angina is brought on by exertion and relieved by rest.
What would be found on examination of a patient with ischaemic heart disease?
Look for signs of risk factors.
May be normal.
What investigations would you perform on a patient with suspected ischaemic heart disease?
Bloods: FBC U and E's CRP Glucose Lipid profile Cardiac enzymes CK-MB Troponin T (sensitive marker of cardiac injury, raised after 12h) Amylase (pancreatitis can mimic MI) TFTs AST and LDH will be raised after 24 and 48hr respectively.
ECG:
Often normal
T wave inversion and ST depression can be found during episode of angina.
Exercise test shows ST segment depression in ischaemic heart disease.
Echocardiogram and Coronary angiography may be useful.
How would you manage a patient with ischaemic heart disease?
Minimize cardiac risk factors!
Aspirin
Beta blockers eg atenolol.
Nitrates, GTN spray
Long acting calcuim antagonists, amlodipine if contraindication to beta blockers.
K+ channel activator, if not controlled
Unstable angina requires admission and urgent treatment.
Invasive treatment is based on restoring vessel patency by balloon or stent or coronary bypass surgery.
What are the possible complications of ischaemic heart disease?
At risk of MI and other vascular diseases.
Cardiac injury can lead secondarily to heart failure and arrhythmias.
Describe the mode of action of beta blockers?
Lower Myocaridal oxygen demand by decreasing heart rate, blood pressure and myocardial contractility
Describe the mode of action of Calcium antagonists?
Cause coronary artery dilatation.
Rate limiting drugs (verapamil or diltiazem) act in similar way to beta blockers.
Describe the mode of action of nitrates?
Dilate the venous and arterial system.
Describe the mode of action of Potassium channel activator?
Similar to nitrates.
Dilate the venous and arterial system.
Describe the mode of action of aspirin?
Prevents platelet aggregation.
Describe the mode of action of clopidogrel?
Acts in similar way to aspirin.
Used if aspirin is not tolerated.
Descibe the mode of action of statins?
Inhibits an enzyme involved in cholesterol synthesis.
HMG-CoA reductase
What are the different types of angina?
Stable angina
-induced by effort, relieved by rest
Unstable angina
- angina of increasing frequency or severity. Occurs on minimal exertion or at rest.
- Associated with high risk of MI
Decubitus angina
-Precipitated by lying flat
Variant (Prinzmetal’s) angina
- Caused by coronary artery spasm.
- (Rare).
