Acute Coronary Syndromes Flashcards
Define stenosis
Narrowing of blood vessels
Define vascular occlusion
Occlusion of blood vessels
What are the three main outcomes of stenosis?
- Inadequate oxygen delivery
- Cramp in affected tissue/muscle
- No residual deficit at first
What does residual deficit mean?
Leftover issues that occur due to a condition
What are the three main outcomes of vascular occlusion?
- No oxygen delivery/tissue death
- More severe pain
- Loss of function of tissues
Define ischaemia
A condition where blood flow (and thus oxygen) is restricted or reduced in a part of the body
define infarction
Tissue death or necrosis due to inadequate blood supply to the affected area
What are acute coronary syndromes?
Type of coronary heart disease. They are a group of conditions, including STEMI, NSTEMI and unstable angina.
What does NSTEMI stand for?
Non- ST elevation myocardial infarction
What occurs during an NSTEMI?
Plaque ruptures and thrombus formation causes partial occlusion to blood vessel and the tissues need for oxygen cant be met
What can an NSTEMI lead to?
damage to the heart and its ability to pump blood throughout the body
What is a STEMI?
The most serious type of MI, where there is long interruption to the blood supply caused by total blockage of the coronary artery
What does STEMI lead to?
Transmural infarction (involving the full thickness of the myometrium)
What occurs during unstable angina?
The plaque ruptures and thrombus forms causing partial occlusion of blood vessel. Angina pain occurs at rest or progresses rapidly over a short period of time.
Why can it be difficult to identify an NSTEMI?
This condition doesn’t have an easily identifiable electrical pattern (ST elevation) like other main types of heart attack.
what is the key bio marker used to diagnose a MI?
Troponin
Define, reversible ischaemia of the heart muscle
Angina
Why does angina occur?
Due to narrowing of one or more coronary artery
What are symptoms of angina pectoris
Tightness in the chest
What is meant by “classical” angina?
Stable angina at rest that worsens with exercise
How would you assess a patient for classical angina?
Ask patient how far they can exercise (e.g. ask them to walk up street with gradient) before they experience chest pain
What is meant by “unstable” angina?
Chest pain (at rest or active) caused by an insufficient flow of blood and oxygen to the heart due to build up of a clot on surface of atherosclerotic plaque, which narrows the artery
What protein is released into the bloodstream during a heart attack?
Troponin
What oral symptoms can occasionally present in a patient suffering from angina?
Toothache or aching pain in jaw
What environment can worsen classical angina?
Cold weather or feelings of emotion (e.g. stress)
Which type of angina deteriorates over time? Classical or unstable?
Classical
True or false?
There are usually signs of classical angina.
False, there are often no signs to be seen
What can occasionally be a sign of classical angina?
Hyperdynamic circulation
Explain what is meant by hyperdynamic circulation
Abnormally increased circulatory volume
What conditions are associated with hyperdynamic circulation?
- Anaemia
- Hyperthyroidism
- Hypovolemia (loss of fluid/water)
Explain the effect severe anaemia has on oxygen carrying capacity of blood and the outcome of this
Oxygen carrying capacity of blood is reduced and therefore the ability of the patient to cope with narrowing of coronary artery is reduced too.
Explain the effect hyperthyroidism has on the demand of oxygen by tissues and why
It increases the demand of oxygen by tissues as it increases the metabolic rate
When carrying out investigations for angina, what should we expect to see from an ECG reading at rest?
It can show no change OR an area of myocardial ischaemia
When carrying out investigations for angina, what should we expect to see from an ECG reading during exercise?
It will show area of myocardial ischaemia
What are the four investigations used to assess angina?
- ECG
- Angiography
- Echocardiography
- Isotope studies
An investigation for angina, where a dye is used to look at patency of arteries.
Angiography
An investigation for angina, where ultrasound is used to look at function of heart valves and ventricles.
Echocardiography
What is the purpose of isotope studies in the investigation of angina?
They look at the proportion of blood ejected from the left ventricle
What changes can be expected on an ECG as ischaemia takes place?
Usually ST elevation, but occasionally ST depression
What symptom of angina does the ST segment elevation on an ECG correlate with?
Pain
what is meant by an “exercise ECG”?
Effectively a treadmill test which tests ischaemia of the heart in real time
What might you observe on an angiogram?
Coronary artery blockage
What is the proportion of blood flow through a vessel in comparison to the radius of a vessel? And what is the outcome of this?
Blood flow through a vessel is proportional to 8 TIMES the radius of a vessel. Therefore for each small reduction in radius, there is a significant reduction in blood flow.
What are the two vital aims of angina treatment?
- Reduce oxygen demands of the heart
- Increase oxygen delivery to the tissues
What are the three ways to reduce oxygen demands of the heart?
- Reduce afterload
- Reduce preload
- Correct mechanical issues (failing heart valves, septal defects)
Define, the pressure the heart is having to work against (blood pressure).
Afterload
Define, venous filling pressure
Preload
What is Starling’s law of the heart in simple terms?
Increasing the filling pressure of the heart will increase the cardiac work
What is the first approach that should be taken for treatment of angina?
Reduce oxygen demands of the heart
What is the second approach that should be taken for treatment of angina?
Increasing oxygen delivery to tissues
What are the two treatment options for increasing oxygen delivery to tissues in a patient with angina?
- Angioplasty
- Coronary Artery Bypass Grafting (CABG)
What does CABG stand for?
Coronary artery bypass grafting
What is an angioplasty?
Using a balloon to stretch open a narrowed or blocked artery
What is normally used in conjunction with an angioplasty?
A stent to hold the narrow vessel open
What is a common treatment for dealing with persistent narrowing of coronary arteries?
CABG
When can non-drug therapy for angina be carried out?
For those who live within the limitations and are able to modify risk factors
What are the three main risk factors to modify in regards to angina?
- Smoking
- Exercise
- Diet (control cholesterol)
what anti-platelet drug reduces the risk of myocardial infarction?
Aspirin
How do diuretics treat hypertension?
Diuretics help rid the body of sodium and water through passage of urine. The sodium takes water with it from the bloodstream, decreasing the amount of fluid flowing through your blood vessels, hence lowering blood pressure.
How do calcium channel antagonists treat hypertension?
They relax (vasodilate) blood vessels and the heart muscle receives more oxygenated blood
How do ace inhibitors treat hypertension?
They prevent an enzyme in the body from producing angiotensin II - a substance that narrows blood vessels- so this helps relax the veins and arteries, lowering blood pressure.
How do beta blockers treat hypertension?
They cause the heart to beat slower and with less force, therefore lowering blood pressure.
what class of drugs can be used to reduce heart filling pressure and dilate coronary vessels?
Nitrates
Give an example of a nitrate drug that works by relaxing blood vessels and increasing the supply of oxygen to the heart, whilst reducing its workload.
Isosorbide
What medication must be used in the em,regency treatment of angina?
GTN spray
what four classes of drugs can be used to treat hypertension?
- Diuretics
- Calcium channel antagonists
- Ace inhibitors
- Beta blockers
What is the function of GTN spray?
Relieves pain of angina by reducing preload (opening the coronary arteries and improving blood supply to heart muscle)
What does the medication GTN stand for?
Glyceryl trinitrate
What two forms can GTN medication be administered in?
Spray or tablet
Where should GTN spray be administered in the mouth?
Sublingually
Why is GTN spray administered sublingually?
Due to first pass metabolism, so that the drug is absorbed quicker.
What is “first pass metabolism”?
A phenomenon of drug metabolism at a specific location in the body which leads to a reduction in concentration of the active drug before it reaches the site of action or systemic circulation
True or false?
CABG can be carried out more than once.
False, CABG can only be carried out once. It is a major surgery with mortality risk.
What individuals have a decreased outcome/benefit from CABG?
Individuals who smoke
what is the risk during angioplasty procedure?
Vessel rupture
In CABG,if veins are used for grafting, why must the be reversed before placed?
So to prevent occlusion of blood valves present in veins
When is CABG not possible?
If there is narrowing along the whole length of an eatery OR if the occlusion is closer to the end of the artery
Where must narrowing of an artery be in order for CABG to be a viable option?
Near the origin of the artery
What issue can arise regarding blood platelets and the stents used in angioplasty procedure?
Blood platelets can stick to the stents metal surface
How can sticking of blood platelets to stent be reduced?
By coating the stent in chemical which will inhibit platelet adhesion or use of anti-platelet drugs
Where does peripheral vascular disease most commonly present and why?
The leg arteries, which are further from the heart, don’t receive enough blood flow to keep up with demand.
what is another word for plaque?
Atheroma
what is the main sign of peripheral vascular disease?
Claudication pain in limb upon exercise
In peripheral vascular disease, as atherosclerosis worsens and narrowing of lumen becomes more pronounced, what happens to claudication distance?
It reduces and patient will experience pain much quicker
True or false?
Atherosclerosis tends to occur around areas of turbulent blood flow, such as where blood vessels branch.
True
why is poor wound healing associated with peripheral vascular disease?
Due to less oxygen delivery to the tissues, so less ability to deliver oxygen and defence cells to area of injury.
what can poor wound healing, in peripheral vascular disease, lead to?
Necrosis and gangrene
Explain what is meant by gangrene
Loss of blood supply causing body tissues to die
What would be the result of necrosis or gangrene of tissues?
Amputation
When plaque detached and travels downstream to block other blood vessels
Embolism
How long does it take for lack of blood flow to cause tissue death?
20 minutes
What determines the degree of functional loss following MI?
The amount of tissue which is infarcted
What is an embolic stroke?
When platelets and clots detach from atherosclerotic plaque in the d arteries and embolise upwards into the cerebral circulation (brain)
In what position to the blockage, is the tissue that will be lost during MI?
Any tissue distal to blockage
Define, the use of drugs to dissolve the blood clot which is causing blockage in blood vessel
Thrombolysis
What does TIA stand for?
Transient ischaemic attack
What is simpler term for TIA?
A mini stroke
A stroke of short duration (<24hrs) is known as what?
Transient ischaemic attack
In what way is cardiac pain communicated to the brain?
Goes through thalamus and the ancient basal brain tissues to reach the cortex
what is a silent myocardial infarction?
Where an individual does not feel any pain symptoms and does not know they have had an MI
On an individual who has had a previous MI, what what feature of ECG would appear larger?
Q wave
Define, the heart stops beating, so there is no cardiac output and therefore most likely results in death.
Cardiac arrest
What equipment should be used in case of cardiac arrest?
A defibrillator
Within what time period does angioplasty and stunting need to occur after onset of MI to prove most effective?
Up to 3 hours
What is the “penumbra”?
The area of tissue surrounding the ischaemic event
What two drugs are most likely to be used in thrombolytic treatment?
- Streptokinase
- Tissue plasminogen activator
what treatment is most appropriate to reduce tissue loss from necrosis after delayed admission (upon to 6 hours after symptoms)?
Thrombolysis
What are the contraindications of thrombolysis and why?
- If the patient has undergone injury/surgery (includes dental extraction)/Intra muscular injections, as recent blood clots would be dissolved.
- Severe hypertension or peptic ulcer disease as this would exacerbate active bleeding
- Diabetic eye disease, liver disease and pregnancy
Death during MI is usually due to what?
A sudden arythmia
Define, the restoration of blood flow to an organ or tissue after having been blocked.
Reperfusion
What are the five main complications of MI?
- Death
- Post MI arrhythmias
- Heart failure
- Ventricular hypofunction and mural thrombosis
- DVT and pulmonary embolism
Post MI treatment, what is the main concern within the first few hours?
Arrhythmias
why may ventricular hypofunction and mural thrombosis occur as a complication of MI?
Due to papillary muscle rupture which may lead to valve disease
Why might deep vein thrombosis and pulmonary embolism be a complication of MI?
Due to immobility during treatment
What drugs could be administered to prevent another MI from occurring?
1.aspirin
2. Beta blocker
3. ACE inhibitor
