Ischaemic Heart Disease And Angina Flashcards
What is the most common cause of stable ischaemic heart disease and low risk unstable angina?
Atheromatous plaques in the coronary arteries which disrupt blood flow
What is angina pectoris?
A typical symptom of ischaemic heart disease resulting from an imbalance between myocardial oxygen supply and demand
What is the nature of anginal pain? (Use SOCRATES)
It is usually a substernal, chest discomfort, described as a pressure or heaviness that is provoked by exercise and relieved by rest or glyceryl nitrate
The pain is sometimes referred and in this case is experienced in the left neck, jaw, epigastric or arm
It typically lasts for several minutes
What are the associated factors of angina?
Dyspnoea on exertion Nausea and vomiting Perspiration Fatigue Hypoxia Tachycardia
What is stable angina?
Stable angina has the most predictable attacks i.e. it is exacerbated by exercise and stress and is the result of an unmet myocardial oxygen demand
What is unstable angina?
This has unpredictable attacks and a coronary artery occlusion component due to platelet adhesion to the ruptured atherosclerotic plaque
What is variant angina?
This results in unpredictable attacks where coronary artery occlusion occurs through vasospasm
Why is coronary artery dilation dangerous in stable and unstable angina?
It may cause coronary steal
Explain the concept of coronary steal
More blood is sent to an already well perfused area which is capable of dilation but in the areas where dilation cannot occur less blood is delivered because of the fall in input pressure
What are the risk factors for ischaemic heart disease?
Advancing age Smoking Hypertension Isolated low HDL cholesterol Elevated LDL cholesterol Diabetes Inactivity Obesity Family history of the disease Illicit drug use Male sex
Internal organs are insensitive to touch, cutting and temperature. What factors, instead, cause pain in visceral organs?
Stretching or chemical changes such as ischaemia
How does the phenomenon of referred pain occur?
The pathways of the visceral organ sensory nerves and somatic sensory nerves converge at the same level of the spinal cord and the signal is then transmitted from here to the brain. Somatic pain is more common than visceral pain, so the brain can confuse the signals resulting in pain from the visceral organs being experienced elsewhere i.e. the skin
Visceral pain is usually sharp and localised whereas somatic pain is dull and poorly localised. T/F?
False the opposite is true
What is the purpose of the initial laboratory tests of haemoglobin, blood glucose and lipid panels when investigating angina?
Haemoglobin is to test for anaemia as this could be a contributing factor for the angina or could be an alternative cause of pain
Lipid panels and blood glucose are used to investigate metabolic abnormalities associated with the risk factors diabetes and hypercholesterolaemia
What is the first investigatory test for angina?
Resting ECG
What protocol is used in an exercise stress ECG?
Bruce protocol
What is the bruce protocol?
A test where the intensity of exercise on a treadmill is gradually increased, the pace and incline are increased every 3 mins up til 21 mins with the heart being monitored on an ECG throughout
What results from an exercise stress ECG could indicate ischaemic heart disease?
ST depression of greater than 2mm
ST segment elevation
Failure to increase systolic blood pressure
Sustained decreased in bp after an appropriate rise during exercise
Low exercise tolerance
What tests other than an exercise stress ECG could be done on a patient when investigating angina and in what circumstances would these tests be performed?
Stress myocardial perfusion imaging
Stress echocardiography
These are done when there are abnormalities in the resting ECG than indicate that an exercise stress ECG should not be performed
What lifestyle factors should be modified to manage ischaemic heart disease?
Encouraging 30-60 mins of moderate intensity aerobic activity at least 5 days per week
Smoking cessation
Weight management
Elimination of stress
How do beta one adrenoceptor blockers work to manage ischaemic heart disease?
The decrease the activity of noradrenaline and adrenalin on the heart to decrease the heart rate which decreases myocardial oxygen demand
How does ivabradine work to manage ischaemic heart disease?
It blocks the sodium current that contributes to SA node depolarisation towards threshold and decreases heart rate but not force which decreases metabolic oxygen demand
What drug is commonly used for prophylaxis in stable angina?
Nitrovasodilators
What other nitrovasodilators exist other than nitroglycerine?
Isosorbide dinitrate
Isosorbide mononitrate
How do nitrovasodilators work to manage ischaemic heart disease?
They readily enter smooth muscle cells where they are reduced to nitric oxide which acts on the blood vessel to induce vasodilation by binding to the haem group of the guanylate cyclase receptor to convert GTP to cGMP
What are the side effects of nitrovasodilators?
Headaches
Tolerance with prolonged use
Vasodilators have a more potent effect on venous dilation than arterial dilation. T/F?
True
In what type of angina is dilatation of the coronary arteries by calcium channel blockers useful?
Variant angina
What is the first line treatment for ischaemic heart disease?
Short acting nitrovasodilator with a beta blocker or calcium channel blocker and drugs for secondary prevention (drugs which act to combat risk factors of the disease e.g. lipid lowering or anti hypertensive drugs)
