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
