Ischaemic Heart Disease Flashcards
What are 4 CVS diseases/problems that atherosclerotic coronary disease can cause?
Chronic coronary insufficiency - angina Unstable coronary disease - MI - sudden ischaemia Heart failure Arrhythmias
What is an epicardial coronary artery? Give one example of an epicardial coronary artery.
Coronary artery that lies on the outer surface of the heart Examples: - LAD - Circumflex -
Where therefore does an endocardial coronary artery lie?
Inner surface of the heart
What is the subendocardial region?
Water-shed area of perfusion and first to become ischaemic
What are the 3 most commonly used types of coronary artery imaging?
Coronary angiography
CT
MRI (measures flow)
List some of the risk factors of coronary artery disease.
Smoking Age Hypertension Hypercholesterolaemia Diabetes Obesity Physical inactivity
What are the 3 main stages in coronary artery disease pathological development?
Fatty streak formation
Fibro-fatty plaque formation
Plaque disruption (rupture/erosion)
How do foam cells form?
Monocytes migrate out of the blood to form macrophages and set about ingesting the fat, forming foam cells
What chemical mediator release stimulates the aggregation of smooth muscle cells?
Cytokine release
What are some of the symptoms of angina?
o Gripping central chest pain
o Radiation to arm and jaw
o Clear and precise relationship to exercise
o Goes 2-10 mins after discontinuation of exercise
o Worse after food. Worse in cold
o No autonomic features
o Flat of hand/fist to describe pain
What is the cause of angina?
Sub-endocardial ischaemia
What abnormality is present on an ECG in cases of angina?
ST wave depression
What is a key issue in cases of epicardial stenosis?
Mismatch of blood supply and demand
What are the two coronary flow regulatory mechanisms?
Auto regulation
Metabolic regulation
In order to a 20 fold increase in total body O2 consumption, by how much can coronary blood flow increase?
5 fold
What does the Adenosine Hypothesis of Coronary Dilation state?
ATP –> AMP – 5-nucleotidase –> adenosine – ADA –> Inosine
What are the 3 main determinants of myocardial oxygen consumption?
Tension development (variable per unit mass of tissue) Contractility (variable) Heart rate (variable) Basal activity (fixed)
What is the function of angina treating drugs?
Reduce myocardial oxygen consumption
What are two other more invasive treatments of angina?
PCI - Percutaneous Coronary Intervention (stents & balloons)
CABG - Coronary Artery Bypass Grafting
List the 4 classes of drug used in angina treatment.
Beta blockers
Nitrates
Calcium channel blockers
Ikf channel inhibitors
What physiological impact do beta blockers have on the CVS?
Reduce BP
Reduce HR
(hence reduce work of heart)
What do nitrates cause in the CVS?
Venodilation –> reduces LV wall tension –> reduced work of the heart
What physiological impact do calcium channel blockers have on the CVS?
Decrease HR
What is the MOA of Ikf channel inhibitors?
Inhibit channels in the SA node –> decrease HR
Which vessel is most appropriate for grafting in place of the RCA?
Saphenous vein
Which vessel is most appropriate for grafting in place of the LAD?
LIMA - Left internal mammary artery
What percentage of MI sufferers do not make it to hospital?
15 - 20%
What is MI mortality in hospital?
6 - 15%
What is the clinical presentation of MI?
Severe chest pain radiating to jaw and arm (generally left)
Autonomic symptoms inc. nausea, sweating, terror, etc.
Breathlessness
What are the 2 main causes of MI?
Plaque rupture
Plaque erosion
List 5 events that can modify MI presentation.
o Time of day o Inflammatory activity o Infection, especially respiratory o Elevation of blood pressure o Catacholamines
What are the 2 main types of MI?
STEMI
NSTEMI
How can an MI be clinically diagnosed?
Raised cardiomyocyte markers in blood (TROPONIN I/T)
Clinical history
For STEMI: ST elevation in ECG
Outline the treatment plan for a STEMI.
First…
- Antiplatelet agents: Aspirin + Clopidogrel
- Immediate revascularisation, i.e. primary PCI or thrombolysis (- clot busting)
Then…
- Beta blockers (reduce myocardial infarction)
- Statin drugs (reduce cholesterol – plaque passivation)
- ACE inhibitors (usually a couple of days later to inhibit dilation of the left ventricle)
What are two complications of STEMI’s that can occur immediately?
Ventricular Arrhythmia and death
Acute Left Heart Failure
What are two complications of STEMI’s that can occur early on?
Myocardial Rupture
Mitral valve insufficiency
Ventricular Septal defect
Mural thrombus and emobolisation
What are two complications of STEMI’s that can occur later on?
LV dilatation and heart failure
Arrhythmia
Recurrent myocardial infarction
In which age group is NSTEMI most prevalent?
The elderly
What is a common cause of NSTEMI and therefore can be implied?
Sub-endocardial ischaemia
What 4 CVS events can predispose to NSTEMI occurrence?
Threatened STEMI
Small branch occlusion
Occlusion of well collateralised vessel
Lateral STEMI in territory not well seen by ECG
Outline the treatment plan for an NSTEMI
Antiplatelet therapy (Aspirin and clopidogrel)
Anti-ischaemics (beta blockers and nitrates)
Statin drugs
ACE inhibitors
Coronary angiography and revascularisation
—> Early if symptoms continue
—> Early if Troponin raised
—> Risk score (e.g. GRACE)
