B.4 Ischaemic Heart Disease Flashcards
What is ischaemic heart disease?
A disease in which there are narrowing and blockage of the coronary arteries (blood vessels that carry blood and oxygen to the heart)
Coronary blood flow does not match demand, leading to ischemia
What is ischaemic heart disease usually caused by?
Atherosclerosis and leads to impaired blood flow or thromboembolic occlusion
What is stenosis?
The narrowing of the artery.
The artery lumen narrows to >70%, reducing blood flow.
This leads to chest pains
What are the risk factors of ischemic heart disease?
Male gender Family history Ethnicity Smoking Diabetes Mellitus Hypercholesterolemia Hypertension Sedentary (inactive) lifestyle Obesity
What does ischaemic heart disease usually cause?
Angina and heart attacks which lead to coronary heart failure
What is stable angina?
Atherosclerotic disease, which limits the hearts’ ability to respond to increase demand-
Symptoms are on exertion but are relieved by rest
What is unstable angina?
Generally due to plaque rupture and the formation of non-occlusive thromboembolism, or less commonly vasospasm
Symptoms occur at rest
What is thromboembolism?
Obstruction of a blood vessel by a blood clot that has been dislodged from another site
How would you diagnose IHD?
Family history
In stable angina, pain induced by exercise and relieved by rest/ GTN
ECG: S-T-segment depression
Angiograph of coronary artery (x-ray of the heart)
How would you manage IHD?
Stop smoking
Exercise
Diet
Weight
Coronary bypass grafting (CABG)
Angioplasty (PTCA) and stenting - less invasive
what are the pharmacological managements of IHD?
Nitrates
How do nitrates work?
They release NO
Which causes vendodilatation, leading to a decrease in preload and a reduction in cardiac work
Coronary vasodilation
How do nitrates work on a pharmacological level?
GTN: glyceryl trinitrate releases NO
NO binds to guanylyl cyclase located in vascular smooth muscle
This increases the generation of cGMP increasing smooth muscle relaxation
This causes vasodilatation
Can people using nitrates for a long period of time become tolerant?
Yes, which reduces the effectiveness of the drug
How can the chances of tolerance be reduced in patients taking nitrates for a long period of time?
Nitrate free period
2 doses rather than 3 doses per day
sustained released preparations: given once daily but do not give 24-hour coverage
Patches: leave off for several hours
What is the first choice drug for preventing IHD?
Beta-blockers
How do beta-blockers work in relation to IHD prevention?
-ve inotropic and chronotropic effects reducing cardiac workload and preventing symptoms
Coronary blood flow only occurs during diastole, then by slowing the heart the diastolic period will be increased, as will the time for coronary blood flow (this will improve coronary blood flow)
Anti-arrhythmic effects and reduced risk of mycardio infarction
What else can be used to prevent IHD?
Calcium channel blockers
What can be used to treat/ prevent angina?
Rate limiting calcium channel inhibitors as they do not cause relax tachycardia like DHP which causes the BP to drop and the heart to speed up
ACEIs can be used in patients with IHD? TRUE/FALSE
True
What can provide relief in patients with ischaemic heart disease?
Potassium channel activators
How does the potassium channel activator Nicorandil work?
Combined NO donor and activator of ATP-sensitive K-channels
The target is the ATP-sensitive K+-channel (K ATP)
The removal of K+ inside the cell causes hyperpolarisation
What drug can be used for IHD and heart failure?
Ivabradine
How does ivabradine work?
Inhibits If channels (pacemaker Na/K current in the SAN
This reduces heart rate
Is ivabradine equally effective as atenolol ut without the beta-blocker side effects?
yes
What can be used to prevent platelet aggregation in patients with IHD?
Low dose aspirin
Clopidogrel
- ADP receptor antagonist
- Equally effective
- Used in patients who can not receive aspirin
- Can be used with aspirin
- Interaction with omeprozol
