Section 4: Cardiovascular disease Flashcards
(52 cards)
1
Q
Outline the stages in the process of atheroma formation
A
1) LDL cholesterol attaches to damaged endothelium
2) Monocytes (WBC) engulfs lipoproteins and develop into foam cells - white cells engulf more and more lipoproteins forming a fatty plaque
3) Foam cells die and release lipid causing smooth muscle cells to divide and begin to produce a matrix of protein and collagen enlarging the size of the plaque
4) Fibrous plaque forms helping contain atherosclerotic plaque
2
Q
What are the 5 typical ways in which the endothelium can become damaged
A
- Shear stress - Force exerted by blood flow
- Nicotine
- Elevated blood glucose
- Oxidized LDL cholesterol
- Chronic inflammatory conditions (rheumatoid arthritis)
3
Q
What are the signs and symtoms of angina?
A
- Tightness in the chest
- Pain/Heavy feeling in left arm but can be right
- Pain in abdomen/back/throat
- Breathlessness on exertion which may occur independently of other symptoms
- Fatigue
4
Q
What are the 4 common triggers to angina and why?
A
- Exercise: Increase HR, Increase in BP (afterload)
- Emotional stress: Increase HR, Increase in BP
- Extremely cold environment: Vasoconstriction of peripheral system (afterload), Vasoconstriction of coronary arteries themselves
- Eating a meal: Increase in HR/Stroke volume (Cardiac output) of about 1 litre per minute
5
Q
What are the characteristics of stable angina?
A
It is predictable in terms of:
- Severity
- How it is relieved e.g resting with or without GTN
- Onset - Is it brought on by similar situations
It is reproducible - brought on at similar workloads
6
Q
How is a patient’s coronary artery disease risk calculated?
A
Rapid access chest pain clinic (RAPC)
- Nature of any chest discomfort
- What triggers the attack
- How long the pain lasts
- How it is relieved
- Patients risk factors for coronary heart disease
7
Q
What information does an ECG provide?
A
- Rhythm (regular/irregular)
- Heart rate
- Whether the electrical activity of the atria is normal
- Presence of teamwork between atria and ventricles
- Whether electrical activity of ventricles is normal
- Adequacy of blood flow to the heart muscle - presence of ischemia seen as ST depression
- Diagnose an acute infarction (ST Elevation MI) or previous infarcts
- The site of infarction
- Arrhythmias
8
Q
What does a Computerised tomography scan involve and who is it commonly used for?
A
- Patients with an estimated CAD risk of 10-29% (low)
CT scan: - Special dye is injected into a vein
- X-ray machine rotates around the body
- Different types of tissue show up with different colors/Pictures showing images of the area scanned
9
Q
What does a myocardial perfusion scan involve and who is it commonly used for?
A
- Patients with an estimated risk of having CAD is 30-60%
MPS: - Patient will exercise to elevate heart rate
- Radio isotope will injected and the patient placed in a scanner
- Ischaemic/Necrotic cells will not take up radio isotope
- Test is repeated with the patient at rest, scans are compared to determine whether ischemia is reversible (only during exercise)
10
Q
When is myocardial perfusion scanning used?
A
- To diagnose CHD
- To determine whether an individual would benefit from a revascularization procedure
- Alternative to ECG ETT in patients that can only manage a minimum amount of exercise
- Can be used in those who cannot perform exercise using drugs that mimic effect
11
Q
Who is a coronary angiography used for and what does it involve?
A
Patients with a 61-90% risk of CHD (high)
- Small tube is passed into femoral or brachial artery into the ascending aorta where openings to coronary arteries are located
- Radio-opaque dye is injected directly into coronary arteries
- Passage of the radio-opaque medium through coronary arteres during the cardiac cycle is visible on X-Ray
12
Q
What are the main uses for coronary angiography?
A
- High likelihood CHD
- Reversible ischaemia proven on myocardial perfusion scan
- Pre-requisite for percustanous coronary intervention or coronary artery bypass graft surgery
- Angina after myocardial infarction (residual)
- Angina diagnosis is uncertain
- Prior to valve replacement surgery to determine whether patient also has CHD
13
Q
What information does a coronary angiography provide and what treatment options might typically be used?
A
- Site and severity of stenoses (blockages)
- Percutaneous coronary intervention
- Coronary artery bypass graft
- Medical management: Aspirin, nitrates, beta blockers, statins
14
Q
What is the recommended procedure for the use of GTN (Glyceryl trinitrate)
A
- Stop activity sit down and rest
- If no immediate relief from chest pain, taken GTN spray/tablets
- Take a second dose after 5 mins
- Dial 999 if no relief after 2nd dose
- If symptoms relieved, rest for 5 mins then rewarm before resuming exercise
15
Q
What durgs are typically used to prevent heart attack/stroke?
A
Aspirin - Antiplatelet drug reduced risk of blood clots forming
Statins - Lower cholesterol levels and slow down further atheroma formation
16
Q
What 4 drugs are typically used to reduce symptoms of angina and how do they work?
A
1) Beta blockers:
- Lowers heart rate, lengthening diastole so coronary perfusion is improve
- Reduced workload by reducing HR, BP and contractility of heart
2) Calcium channel blockers:
- Increase blood supply by vasodilating coronary arteries and inhibiting smooth-muscle contraction and resulting coronary artery spasm
3) Potassium channel activators:
- Increase perfusion by dilating coronary arteries
- Dilate veins to reduce preload and dilate arteries reducing afterload
4) Ivabradine
- Increases blood supply to the heart by reducing HR therefore lengthening diastole and increasing coronary perfusion
17
Q
Outline the revascularisation treatments for angina
A
Percutaneous coronary interventions - Restore blood flow by widerning lumen of narrowed artery with a stent
Coronary artery bypass graft - Bypasses blocked artery by taking artery/vein somewhere else in the body
18
Q
How does acute coronary syndrome occur and what are the different types?
A
Fibrous plaque ruptures with sticky platelets adhering to the ruptured area forming a clot or thrombus - Unstable angina - Myocardial infarction NSTEMI (no ST Elevation on ECG) STEMI (ST Elevation on ECG)
19
Q
Outline the guidelines for diagnosing acute coronary syndrome
A
- Resting ECG
- Blood tests
Troponins should be tested 6-12 hours after initial assessment to indicate cardiac injury - Unstable angina will also test for history
20
Q
How does unstable angina occur and how does it present itself?
A
- Occurs when platelets stick but dissolve on their own
- New-onset angina - no pattern is yet established
- Angina at rest
- Increased, frequency and severity
- Occurs at lower levels than normal
21
Q
Outline the signs and symptoms of a myocardial infarction
A
Symptoms: - Intense pain or pressure in the chest that may be described as crushing, band like, or squeezing - Pain in the throat and arms (particularly left) - Similiar to indigestion - Discomfort in arm/throat alone - Discomfort in the abdomen or back Signs: - Breathlessness - Nausea/vomiting - Pale, cold and clammy - Agitation and fearful-feeling of impending doom - Weakness, sometimes collapse
22
Q
What are the typical recommendations from someone with suspected myocardial infarction?
A
- Chew on an aspirin tablet (300mg)
- Use GTN to distinguish between angina and MI
- Echocardiogram - particularly good for silent infarction
- Morphine - reduces adrenaline and calms people down
23
Q
How might an MI be diagnosed?
A
- Echocardiogram ST-elevation is a common sign of MI NSTEMI is generally less severe
- Blood rests for troponin - more troponin indicates more damage
24
Q
What do patients in hospitals who have had a myocardial infarction typically receive and what can they help identify?
A
- Echocardiogram will determine the extent to which LV function is effected
- Myocardial perfusion - detects area which would benefit from revascularization
- ECG ETT - Detects ischemia - lower intensity = poorer prognosis
- Coronary angiography - Determine the site and severity of disease within an artery
- MRI - Gives more detailed structure of blood vessels and different structures of the heart
25
What does an echocardiogram involve what information does it provide?
- A non-invasive technique the chest is covered with gel and pulses of ultrasound is applied to the chest wall and are reflected back to create a moving image of the heart
Provides information regarding:
- Measurement of ejection fraction/determining LV function
- Thickness of the atrial and ventricular wall
- Motion of atrial and ventricular wall
- Competence of valves
- Presence of abnormalities such as a thrombus within the ventricles
26
When is an echocardiogram used?
- Post MI
- Left ventricular function and heart failure
- In valve disease
27
What does an MRI involve and what 9 piece of information does a cardiac MRI provide?
- Use of magnetic field and radio waves produce detailed images of the body to be produced
Information:
- Size of the heart's chamber
- Thickness of atrial and ventricular wall
- Motion of atrial and ventricular wall
- Ejection fraction
- Competence of valves
- Presence of abnormalities such as a thrombus
- Assess myocardial viability
- Identify stress-induced myocardial ischemia
- Differentiate forms of cardiomyopathies
28
What does an ECG ETT involve and how is it carried out?
- An incremental test used to induce ischemia
1) ECG is continuously recorded
2) BP is measured
3) Rate and incline of the treadmill is increased every 3 minutes using modified bruce and full bruce protocol
4) Feelings of pain and ST-segment depression are recorded to indicate ischemia
29
What information does ECG ETT provide?
- Establish the extent and severity of disease in someone with established symptoms
- Confirm residual ischemia post-myocardial infarction
- Assess the effectiveness of treatment following surgery or rehabilitation (less common)
30
When are the results of an ECG ETT said to be positive and negative?
Positive:
- Chest pain during exercise
- ST-segment depression (<2mm) indicates ischemia
- Drop-in BP may indicate a reduction in a reduction in cardiac output due to poor left ventricular function
- Serious arrhythmias (ventricular tachycardia)
Negative:
- Patient reaches age-adjusted maximal heart rate without signs or symptoms
31
Why might an ECG ETT be terminated?
- Patient reaches their age-adjusted maximal heart rate
| - Patient is very fatigued or experiences excessive breathlessness
32
Outline the process through a coronary artery bypass graft?
- Performed under general anaesthetic through incision in the sternum
- Obstructed coronary arteries are bypassed using an internal mammary artery, radial artery, or a saphenous vein
- The patient is placed on a lung bypass machine
- The sternum has been split so recovery takes longer then PCI with several days required in hospital
- Cardiac rehabilitation occurs 6-weeks post-surgery
33
What is elective PCI and when is it not appropriate?
A patient whose symptoms are not adequately controlled undergo planned angioplasty
Not appropriate for:
- Numerous diffuse lesions
- Stenoses where artery bifurcates
- The lesion is in the left main stem and therefore blood flow to the whole left ventricle is jeopardized
34
What does a percutaneous coronary intervention involve and what are the two different types?
Elective (planned) and primary (immediatly following)
1) Special balloon catheter is introduced to brachial/radial/femoral artery and is directed to coronary stenosis
2) Balloon is inflated and atherosclerotric plaque is is widened agaisnt arterial wall
3) Stent is inserted also to open widened section
4) Stent is coated in slow releasing drug that retards tendency of the intima to grow through stent
35
Outline the 7 long and short complications of heart surgery?
1) Pain/Numbness: Occurs especially over left side if internal mammary artery (chest) has been used, thoracic discomfort from resulting compensation for chest pain
2) Atrial fibrillation: Occurs in 20-30% patients 2-5 days post surgery
3) Wound infection: Sternum and places from where artery was taken - diabetics are particularly slow to heal
4) Clicking sternum: Poor/Slow healing can cause a clicking sound
5) Brachia palsy: Nerve compression manifests itself as slight numbness in fingers (lasts up to 6 months)
6) Loss of appetite and constipation
7) Emotional/Psychological side effects
36
Outline the standard drug therapies for acute coronary syndromes?
Aspirin: Reduces the likelihood of blood clots forming
Clopidogrel, prasurgel, tricagrelo: Combined with aspirin as a second anti-platelet drug
Beta-blockers: Prescribed even without persistent angina
ACE inhibitors: Reduce potential in deterioration in left ventricular function and onset of chronic heart failure
Statins: Reduces cholesterol and chance of further atheroma formation
GTN spray: For relief in future event
37
What are 3 common complications following acute coronary syndrome and how is the likelihood of these complications increased?
1) Residual angina
2) Left ventricular dysfunction and chronic heart failure
3) Arrhythmias and sudden cardiac death
Complications:
Site of infarction is anterior - ECG indicates which site the infarction has occured in
Size of infarction is large - Indicated by levels of troponin
38
Summarise the main information given by a ECG, ECG ETT, Myocardial CT, Myocardial perfusion, Echocardiogram, Cardiac MRI, and a angiogram
- ECG: Heart rhythm (arrhythmias), Diagnose MI (ST elevation), Site of MI
- ECG ETT: Provoke ischemia on exercise - ST depression
BP response - drops indicate poor function/CHD
Myocardial CT scan: Indicate calcium score and likelihood CAD
- Echocardiography: Measurement of ejection fraction, Size of heart chambers, Thickness of walls, Motion of atrial and ventricular walls, Competence of valves, Presence of abnormalities such as thrombus
- Cardiac MRI scans: Myocardial viability, Stress-induced myocardial ischemia, Dirrentiate cardiac
myopathies
- Angiogram: Identify stenoses, Decide on appropriate treatment (PCI/CABG)
39
What is left ventricular dysfunction defined as and what are the 6 common causes?
- Ejection fraction reduced to less than 50%
- Causes:
1) MI (mainly)
2) Chronic hypertension
3) Atrial fibrillation
4) Valve disease
5) Alcohol and illicit drug abuse
6) Cardiomyopathy
- Hypertrophic cardiomyopathy (enlargement of heart)
- Dilated cardiomyopathy (large thin-walled left ventricle)
40
How does MI typically develop into left ventricular dysfunction?
- Impairment filling (less compliant) - reduced preload and therefore stroke volume
- Loss of cardiac muscle mass reduces cardiac muscle mass and therefore emptying
- Thickening left ventricle to compensate (remodelling) sympathetic activity increases also
- Increased blood pressure from increased sympathetic activity increases work on heart into systemic circulation
41
Define heart failure and the classfication given by the New York Heart Association?
- Heart failure occurs when the left ventricle is unable to maintain a cardiac output that is adequate to meet the oxygen demands of the body
Class l: No limitation - asymptomatic left ventricular dysfunction
Class ll: Slight limitation of physical activity - fatigue, dyspnoea or angina
Class lll: Marked limitation at lower workloads of physical activity
Class llll: Symptoms of heart failure even at rest - can't continue exercise without any physical activity.
42
What are the signs and symptoms of heart failure and the underlying cause?
1) Shortness of breath
2) Fatigue
3) Pitting oedema in the feet, ankles and sacrum
4) Reduced exercise capacity
- Blood backing up in pulmonary circulation with failure of left ventricle
- Blood backing up in system circulation with failure of right ventricle
43
How is heart failure diagnosed?
- ECG indicating left ventricular hypertrophy, previous MI or arrhythmias such as atrial fibrillation
- Echocardigraphy:
>50% Good LV
40-49% Moderate LVF
<40% Poor LVF
- Chest X-ray to detect cardiac enlargement
- Blood tests for brain natriuetic factor (hormone released in heart failure to stimulate salt and water excretion)
44
What are the two types of heart failure and why is it important to distinguish between the two?
- Heart failure with reduced ejection fraction
- Heart failure with preserved ejection fraction - refers to other forms of heart failure whether caused by stiff left ventricle or not
- Drug treatments with poor progrnosis only effective in patients with HFREF
45
What is the average age of someone with heart disease and what is the survival rate of those discharged?
- Average age of 74 yearrs
- 25% discahrge with acute heart failure died within 12 months (previously 50%)
- Heart failure with reduced ejection fraction is treatable by medication
46
What are the aims of medication for those with low ejection fraction
- Reduced myocardial workload (Rate pressure product)
- Remove excess fluid
- Reduce remodelling
47
What is an arrhythmia?
- Those not controlled by the sinus (sinoatrial node)
- Those not 60-100bpm
- Tachycardia, bradycardia, irregular rhythm
48
How are arrhythmias investigated?
- Continous ECG to diagnose intermittent symptoms e.g blackout runs of tachycardia or palpitations.
- Ambulatory equipment allows recording of the electrocardiogram throughout periods of rests and activity
- Blood tests to exclude other causes such as anaemia
49
What is the definition of tachycardia and outline the different types?
- Resting bpm >100bpm
- Supraventricular: Stemming from atria typically leads to fainting, dizziness
- Ventricular: Stemming from ventricles commonly caused by acute MI - dizziness commonly leading to collapse due to loss of blood pressure - commonly leads to cardiac arrest
50
How is ventricular tachycardia and fibrillation diagnosed?
- Resting ECG
- Electrophysiology studies to test for abnormalities of electrical system
- Echocardiogram
- Blood tests for underlying cause
51
What is the acute treatment for ventricular tachycardia?
- Defibrillation (Shock causing depolarisation of myocardium allowing Sinoatrial node opportunity to return to normal rhythm)
- Direct current cardioversion - similar to defibrillation but performed with the patient under general anaesthetic before shocks are delivered
- Medication: Anti-arrhythmics drugs (amiodarone)
- Radiofrequency ablation: Radiofrequency ablation to destroy area of rogue cells identified on electrophysiology
- Implantable cardioverter-defibrillator (ICD): To control heart rate an to deliver an electrical shock
52
What is bradycardia and what are the common causes?
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