Cardiovascular Flashcards
What is the principal cause of heart attack, stroke and gangrene of extremities?
Atherosclerosis
What is the best known risk factor for coronary artery disease?
Age
Besides age, what are five other risk factors for atherosclerosis?
- Smoking
- Obesity
- Family history
- High serum cholesterol (LDL)
- Diabetes
What 4 things make up an atherosclerotic plaque?
- Lipid
- Necrotic core
- Connective tissue
- Fibrous ‘cap’
What two things can happen to an atherosclerotic plaque?
- It can occlude the vessel lumen, restricting blood flow
2. It can rupture, leading to thrombus formation
Why do high LDL levels increase the risk of coronary artery disease?
LDL can pass in and out of the arterial wall and can be oxidised and glycated when it accumulates in the arterial wall. This can lead to endothelial dysfunction, causing the endothelium to not relax properly.
How is GTN used to prevent arterial disease?
GTN converts to nitrous oxide in the body and relaxes the vessel walls
What two things might be elevated in the bloods of a patient who has had a recent MI?
C-reactive protein (non-specific inflammatory marker)
Troponin (indicator of whether heart has been damaged)
How can canakinumab and tocilizumab be used to treat atherosclerosis?
Antibodies to IL-1 and IL-6 respectively, decreases inflammation in the vessel by decreasing the chemoattractants.
What is stage 1 of atherosclerosis?
Fatty streaks consisting of aggregations of lipid-laden macrophages and T lymphocytes within the intimal layer of the vessel wall.
What are stage 2 (intermediate lesions) of atherosclerosis comprised of?
Lipid laden macrophages (foam cells) Vascular smooth muscle cells (abnormal) T lymphocytes Platelets (complete with aggregation and adhesion to vessel wall) Isolated pools of extracellular lipid
Stage 3 atherosclerotic plaques can impede blood flow and are prone to rupture. What prevents contact with the flowing blood?
They are covered with a dense fibrous cap made of ECM proteins including collagen and elastin.
Why would an atherosclerotic plaque rupture? (stage 4)
Because the fibrous cap has to be constantly resorbed and deposited to be maintained. If the balance is shifted in favour of inflammatory conditions (i.e. increased enzyme activity), the plaque becomes weak and can rupture.
What is stage 5 of atherosclerosis?
Plaque erosion
What is PCI?
Percutaneous coronary intervention, i.e. stents
How does aspirin help prevent coronary artery disease?
Irreversible inhibitor of COX, inhibits platelet aggregation
How do clopidogrel and ticagrelor help prevent coronary artery disease?
Inhibit platelet aggregation by inhibiting the P2Y12 ADP receptor on platelets
How do statins help prevent coronary artery disease?
Inhibit HMG CoA reductase, thereby reducing cholesterol synthesis
What drug used for gout and pericarditis may be repurposed for patients with recent MI?
Colchicine - has been found to lower risk of ischaemic events in patients with recent MI
What are the 3 types of pacemakers found in the heart?
- SA node (dominant pacemaker, intrinsic rate of 60-100bpm)
- AV node (backup pacemaker, intrinsic rate of 40-60bpm)
- Ventricular cells (backup pacemaker, intrinsic rate of 20-40bpm)
On an ECG, what does the P wave represent?
Atrial depolarisation
On an ECG, what is the PR interval and what does it represent?
Starts at origin of P wave to start of QRS complex - includes SA depolarisation, atrial depolarisation and conduction through the AV node and bundle of His.
How much time do the large and small boxes on the ECG represent? (Horizontally)
Small box = 0.04s
Large box = 0.2s
What voltage does a large box on an ECG represent vertically?
0.5mV
Which ECG leads show activity on the lateral right side?
I and aVL
Which ECG leads show activity on the lateral left side?
V5 and V6
Which ECG leads show activity on the inferior surface of the heart?
II, III and aVF
Which ECG leads show septal activity in the heart?
V1 and V2
Which ECG leads show anterior activity in the heart?
V3 and V4
What is Rule 1 for a normal ECG?
PR interval should be 120-200ms (3-5 little squares)
What is Rule 2 for a normal ECG?
The width of the QRS complex should not exceed 110ms (3 little squares)
What is Rule 3 for a normal ECG?
QRS complex should be dominantly upright in leads I and II
What is Rule 4 for a normal ECG?
QRS and T waves tend to have the same general direction in the limb leads
What is Rule 5 for a normal ECG?
All waves are negative in aVR
What is Rule 6 for a normal ECG?
R wave progression - R wave must get larger from V1 to at least V4 and the S wave must get larger from V1 to at least V3 and disappear in V6
What is Rule 7 for a normal ECG?
The ST segment should start isoelectric except in V1 and V2, where it may be elevated
What is Rule 8 for a normal ECG?
The P waves should be upright in I, II and V2 to V6
What is Rule 9 for a normal ECG?
There should be no Q wave or only a small q <0.04s in width in I, II and V2 to V6
What is Rule 10 for a normal ECG
The T wave must be upright in I, II, V2 to V6
The P wave is best seen in which lead?
Lead II
What can tall P waves (>2.5 little squares) indicate?
Right atrial enlargement
What can bifid (M shaped) P wave in limb leads represent?
Left atrial enlargement
What might cause a short PR interval?
An accessory pathway, which bypasses the AV node and allows early activation of the ventricle (as seen in Wolff-Parkinson-White syndrome)
What does a long PR interval signify?
A first degree heart block
What does the T wave on an ECG represent?
Ventricular repolarisation
What does a normal T wave look like?
Asymmetrical with a more gradual slope in the first half, at least 1/8 but <2/3 of the amplitude of the R wave, following the direction of the QRS deflection.
In which lead is the QT interval measured?
aVL
What is the QT interval and what does it measure?
Beginning of QRS complex to the end of the T wave, measures total duration of depolarisation and repolarisation.
What happens to the QR interval when heart rate increases?
It decreases
How long should the QT interval be?
0.35-0.45s, not more than half the R-R interval
What is a U wave?
A small, round, symmetrical wave, which has a positive deflection in lead II (same as T wave) and is more prominent in slower heart rates. It signifies after-depolarisations which follow repolarisation.
What are the 4 most common diseases of the heart valves and which one is by far the most common?
- Aortic stenosis (most common)
- Mitral regurgitation
- Aortic regurgitation
- Mitral stenosis
What is the normal aortic valve area?
3-4cm2
At what point do symptoms of aortic valve stenosis normally occur?
When the valve area is reduced to about 1/4 of normal
Give a congenital cause of aortic valve stenosis
Congenital bicuspid valve
Bicuspid aortic valve affects about 0.5-2% of the population. At what age do symptoms generally appear?
30s-50s
What are two more common causes of acquired aortic stenosis?
- Degenerative calcification - usually doesn’t cause symptoms until 70s-80s
- Rheumatic heart disease leading to adhesions and fusion of commissures and cusps
How does the heart initially compensate for aortic stenosis?
Increased afterload due to pressure gradient between the left ventricle and aorta leads to compensatory left ventricular hypertrophy.
Name 4 ways in which symptomatic aortic stenosis can present
- Syncope (heart works harder, but BP drop due to aortic stenosis)
- Angina (due to increased myocardial oxygen demand)
- Dyspnoea (on exertion)
- Sudden death (<2%)
Describe what might be heard on auscultation of a patient with aortic stenosis
- Soft/absent second heart sound (second heart sound = closure of aortic valve)
- S4 gallop due to left ventricular hypertrophy
- Ejection systolic murmur (crescendo-decrescendo due to turbulence across the aortic valve)
What measurements would be obtained on an echocardiogram for a patient with suspected aortic valve stenosis?
- Left ventricular size (check for hypertrophy), dilation and ejection fraction to check function)
- Gradient and AVA (aortic valve area)
Aortic stenosis can be graded as mild, moderate or severe. What measurements are used to grade?
Aortic valve area
Velocity of blood flow
Why do patients with aortic stenosis need to be really careful about their dental hygiene?
Because of the increased risk of infective endocarditis
Why does medical management play a limited role in aortic stenosis?
AS is a mechanical problem
What kind of drugs are contraindicated in severe aortic stenosis?
Vasodilators
What procedure is normally used to replace a stenotic aortic valve?
TAVI = transcatheter aortic valve implantation
Which patients are candidates for aortic valve replacement?
- Any symptomatic patient with severe aortic stenosis (including symptoms with exercise)
- Any patient with decreasing ejection fraction
- Any patient undergoing CABG with moderate/severe AS
What are the signs of mitral regurgitation on auscultation?
- Pansystolic murmur at the apex radiating to the axilla
- S3 sound (due to congestive heart failure or LA overload)
- Displaced hyperdynamic apex beat
Patients with asymptomatic severe mitral regurgitation have a 5%/year mortality rate. At what point does mortality rise sharply?
Once the patient’s ejection fraction drops below 60% or the patient becomes symptomatic (e.g. decreased exercise tolerance)
What investigations should be requested if mitral regurgitation is suspected?
ECG, chest x-ray, echo (particularly transoesophageal echo)
What might an ECG show if a patient has mitral regurgitation?
Signs of left atrial enlargement, atrial fibrillation and left ventricular hypertrophy
What 4 types of medication might be given for mitral regurgitation?
- Vasodilators (e.g. ACE inhibitors, hydralazine)
- Beta blockers/calcium channel blockers/digoxin for rate control
- Anticoagulation for AF and flutter
- Diuretics for fluid overload
What is used to monitor mitral regurgitation?
Serial echocardiography - frequency depends on severity
What are the indications for surgery in cases of severe mitral valve regurgitation?
Any symptoms at rest or exercise
In asymptomatic patients: if ejection fraction drops below 60% or if LVESD >45mm
What is the definition of aortic regurgitation?
Leakage of blood into the left ventricle during diastole due to ineffective coaptation of the aortic cusps
What are three possible causes of chronic aortic regurgitation?
- Bicuspid aortic valve
- Rheumatic causes
- Infective endocarditis
Aortic regurgitation results in pressure and volume overload. What compensatory mechanisms might be seen?
Left ventricle dilatation and hypertrophy
What would BP measurements in a patient with aortic regurgitation likely show?
Wide pulse pressure
What would auscultation examination of a patient with aortic regurgitation likely show?
- Diastolic blowing murmur at the left sternal border
- Austin flint murmur (apex) caused by vibration of the anterior mitral valve leaflet
- Systolic ejection murmur due to increased blood flow across the aortic valve
Around what age does aortic regurgitation normally become symptomatic?
40s-50s
What are the progressive symptoms of aortic regurgitation?
Dyspnoea (exertional, orthopnoea and paroxysmal nocturnal dyspnoea)
Palpitations due to increased force of contraction and ectopics
How would aortic regurgitation be evaluated radiologically?
- Chest x-ray would show enlarged cardiac silhouette and aortic root enlargement
- Echo can be used to assess LV dimensions and function
How is aortic regurgitation managed?
- Consider IE prophylaxis
- Vasodilators (ACEis can be used to improve stroke volume and reduce regurgitation if patient is symptomatic or hypertensive)
- Serial echocardiograms to monitor progression
- Surgical treatment (definitive)
What are the indications for surgical treatment of aortic regurgitation?
- Any symptoms at rest or exercise
2. If asymptomatic: if EF drops below 50% or if LV becomes dilated
What is the definition of mitral stenosis?
Obstruction of the LV inflow that prevents proper filling during diastole
What is the predominant cause of mitral stenosis?
Rheumatic carditis
What are two less common causes of mitral stenosis?
Infective endocarditis and mitral annular calcification
Progressive dyspnoea can occur in patients with mitral stenosis as a result of left atrial dilation, which causes pulmonary congestion due to reduced emptying. What might trigger this symptom?
Exercise, fever, tachycardia and pregnancy
Besides dyspnoea, what are the other clinical features of mitral stenosis?
LA enlargement
Atrial fibrillation
Haemoptysis (due to rupture of bronchial blood vessels due to pulmonary hypertension)
Right ventricular hypertrophy
Mitral facies (vasoconstriction as a result of diminished cardiac output –> pink-purple patches on cheeks)
What causes people to die from mitral stenosis?
Progressive pulmonary congestion
Infection
Thromboembolism
What distinctive heart sounds are heard in patients with mitral stenosis?
- Diastolic murmur - low pitched diastolic rumble most prominent at the apex
- Loud opening S1 ‘snap’ due to abrupt halt in leaflet motion in early diastole
What investigations are used to evaluate mitral stenosis?
ECG, chest x-ray, echo
What might an ECG show in cases of mitral stenosis?
Atrial fibrillation and evidence of left atrial enlargement
What might be seen on a chest x-ray of a patient with mitral stenosis?
Left atrial enlargement and pulmonary congestion, possible calcification of mitral valve
What three things are used to categorise mitral stenosis as mild, moderate or severe?
- Mean pressure gradient
- Pulmonary artery systolic pressure
- Valve area
Mitral stenosis is a mechanical problem and medication cannot halt progression. However, beta blockers, calcium channel blockers and digoxin might still be prescribed. Why?
These drugs have a chronotropic effect on the heart- slowing the heart rate prolongs diastole and allows improved diastolic filling.
Which patients should be considered for mitral valve replacement?
- Any symptomatic patient
- Asymptomatic moderate/severe MS with a pliable valve suitable for percutaneous mitral balloon valvotomy
When might physiological hypertrophy of the heart occur?
In athletes and during pregnancy
Congenital heart disease affects up to 1% of all live births. What are the four most common congenital heart conditions?
Ventriculoseptal defect
Atrioventricular defect
Patent ductus arteriosus
Tetralogy of Fallot
Give four potential causes of congenital heart disease
- Genetic causes e.g. trisomy 21, Turner syndrome, homeobox gene mutations
- Infections e.g. rubella
- Drug and alcohol use
- Diabetes
Acute rheumatic fever is associated with which pathogenic organism?
Group A beta-haemolytic strep
Acute rheumatic fever is most common in which age group?
Peak age 9-11 years but can occur in adults
What are the clinical features of acute rheumatic fever?
Carditis, polyarthritis, chorea, erythema marginatum and subcutaneous nodules
How does acute rheumatic fever affect the heart?
The antibodies that are produced in response to the group A beta-haemolytic strep infection cross-react with cardiac myocytes and valvular glycoproteins, resulting in inflammation and scarring. This messes up the valves and results in progressive cardiac dysfunction. Also provides a favourable site for bacterial infection, increasing risk of infective endocarditis.
Name three inflammatory disorders other than acute rheumatic fever that can affect cardiac valves
- Systemic lupus erythematosus
- Rheumatoid arthritis
- Ankylosing spondylitis
What is the most common aetiology of myocarditis?
Viral (Coxsackie, adenovirus, ECHO, influenza)
What is the most common type of vasculitis?
Giant cell arteritis
Giant cell arteritis is more likely to affect which groups of people?
Female, 70+
Where are berry aneurysms found?
In the cerebral circulation, particularly between branching points of the circle of Willis
What is the major risk of a berry aneurysm?
Subarachnoid haemorrhage, leading to sudden death
What is a dissecting aneurysm?
When a haematoma forms within the arterial wall with blood entering under pressure from the luminal surface, which then results in dissection along the length of the media.
Name 2 things that increase the risk of dissecting aneurysm
- Hypertension
2. Degenerative arterial disease (e.g. Marfan syndrome)
What is Virchow’s triad?
Three things that lead to thrombus formation:
- Endothelial injury
- Stasis/turbulence of blood flow
- Increase in blood coagulation
What is an embolus?
A detached intravascular solid, liquid or gas bolus that moves from one part of the circulation to another - most are thrombus in origin but can be e.g. cholesterol, foreign body, tumour etc.
What is a haemangioma?
Benign proliferation of blood vessel tissue
What is a haemangioendothelioma?
A vascular tumour of endothelial cells of low grade malignancy
What is an angiosarcoma?
A highly aggressive neoplasm of endothelial cells, can be caused by environmental carcinogens such as arsenic and vinyl chloride
What is Ehlers-Danlos syndrome?
A group of disorders with abnormal collagen synthesis
Which type of Ehlers-Danlos syndrome is associated with spontaneous arterial rupture and aneurysm formation in early adulthood?
Type IV
What causes angina?
A mismatch of oxygen supply and demand caused by a narrowed artery. If a patient exerts themselves, the blood can’t reach the distal myocardium in required amount, leading to pain
What are the 6 most important predisposing factors to ischaemic heart disease?
- Age
- Smoking
- Family history
- Diabetes mellitus
- Hypercholesterolaemia
- Hypertension
Name 5 conditions that can exacerbate ischaemic heart disease
- Anaemia (decreases supply)
- Hypoxia (decreases supply)
- Hypertension (increases demand)
- Tachyarrhythmia (increases demand)
- Hyperthyroidism (increases demand)
Name 4 environmental factors that can exacerbate ischaemic heart disease
- Exercise
- Cold weather
- Heavy meal
- Emotional stress
(anything that increases cardiac output/oxygen demand)
When does myocardial ischaemia occur?
When there is an imbalance between the heart’s oxygen demand and supply, usually because of an increase in demand (e.g. from exertion) accompanied by a limitation of supply (e.g. from impairment of blood flow or increased resistance)
What cardiac symptoms tend to accompany ischaemic heart disease?
Central chest pain/tightness/discomfort
Breathlessness without fluid retention
What cardiac symptoms do not tend to accompany ischaemic heart disease?
Palpitations and syncope
Name 7 possible causes of chest pain
- Ischaemic heart disease
- Pericarditis/myocarditis
- Pulmonary embolism/pleurisy
- Chest infection/pleurisy
- GORD
- Musculoskeletal chest pain (particularly in arthritis)
- Psychological
How is chronic stable angina treated?
- Lifestyle changes (smoking cessation, weight loss, exercise, dietary changes)
- Advice for emergency (999 if pain is prolonged and feel ill)
- Medication - GTN spray for when it comes on, aspirin, beta blocker, statin, ACEI
- Consider revascularisation if patient is unresponsive to medication
What is the first line of investigation for patients with suspected coronary disease?
CT coronary angiography