Cardiovascular Flashcards
What is atherosclerosis?
The build up of plaque (made up of fats, cholesterol, cellular waste products, calcium and fibrin) in and on the artery walls which results in thickening or hardening of the arteries.
What are 7 major risk factors for atherosclerosis?
- Age
- Tobacco smoking
- High serum cholesterol
- Obesity
- Diabetes
- Hypertension
- Family history
What is a neointima?
A new or thickened layer of arterial intima formed in atherosclerosis by migration and proliferation of cells from the media.
What are 6 inflammatory cytokines found in plaques?
IL-1, IL-6, IL-8, IFN-y, TGF-b, MCP-1
What is the structure of an atherosclerotic plaque?
- Lipids (incl. cholesterol)
- Necrotic core (dead cells)
- Connective tissue
- Fibrous cap
What are the steps of atherosclerosis?
- Endothelial dysfunction
- Formation of lipid layer or fatty streak within the intima.
- Migration of leukocytes and smooth muscle cells into the vessel wall
- Foam cell formation and degradation of the extracellular matrix
What is a fatty streak?
The earliest lesion of atherosclerosis which consists of aggregations of lipid-laden macrophages and T-lymphocytes within the intimal layer of the vessel wall.
What are the constituents of intermdiate atherosclerotic lesions?
- Lipid laden macrophages (foam cells)
- Vascular smooth muscle cells
- T lymphocytes
- Adhesion and aggregation of platelets to vessel wall
- Isolated pools of extracellular lipid
What are the characteristics of fibrous plaques or advanced lesions?
- Impedes blood flow
- Prone to rupture
- Covered by dense fibrous cap made of extracellular matrix
proteins including collagen (strength) and
elastin (flexibility) laid down by smooth muscle cells that
overly lipid core and necrotic debris - May be calcified
- Contains: smooth muscle cells,
macrophages and foam cells and T
lymphocytes
What occurs when the atherotic plaque ruptures?
Plaques constantly grow and recede and if there is increased enzyme activity it can reach the fibrous cap and cause rupture so the basement membrane, collagen, and necrotic tissue are exposed to blood and a thrombus forms resulting in partial or complete vessel occlusion.
What is plaque erosion?
Second most prevalent cause of coronary thrombosis.
- Usually occurs in early lesions with a small lipid core and thickened fibrous cap
- Results in a ‘white thrombus’ formed of platelets and fibrinogen rather than a red thrombus of RBCs and fibrin
What is the difference between plaque erosion and rupture?
Plaque rupture is the disruption of a fibrous cap over a lipid core, erosion is the superficial disruption of a fibromuscular plaque without a core.
Where does atherosclerosis occur?
Within peripheral and coronary arteries with focal distribution along the length of the artery.
What is acute coronary syndrome?
A spectrum of acute myocardial ischaemia and/or infarction (unstable angina, STEMI, NSTEMI)
Define unstable angina
Myocardial ischaemia at rest or on minimal exertion in the absence of acute cardiomyocyte injury/necrosis.
What are 5 risk factors for acute coronary syndrome?
- Diabetes mellitus
- Hyperlipidaemia
- Hypertension
- Metabolic syndrome (abdominal obesity, hypertension, impaired fasting glucose, high triglyceride levels, and low HDL cholesterol levels)
- Renal impairment
What are 5 key symptoms of unstable angina?
- chest pain
- excessive sweating
- epigastric pain
- dyspnoea
- syncope (fainting)
What is the first line investigation for acute coronary syndrome?
ECG
What is the first line treatment for ACS?
Aspirin 300mg
What is the key presentation for STEMI?
New or increased and persistent ST-segment elevation in at least 2 contiguous leads (leads connecting to adjoining areas of tissue)
What is the acute management for STEMI?
MONA
Morphine
Oxygen (if sats <94%)
Nitrates
Aspirin
What is the key presentation for NSTEMI?
elevated troponin levels
What are the possible mechanisms leading to a NSTEMI?
- Plaque rupture with superimposed non-occlusive thrombus or embolic events leading to coronary vascular obstruction
- Dynamic obstruction, such as in vasospasm
- Progressive luminal narrowing (i.e., chronic arterial narrowing from restenosis)
- Inflammatory mechanisms (i.e., vasculitis)
- Extrinsic factors leading to poor coronary perfusion (such as hypotension, hypovolaemia, or hypoxia).
What are myocardial infarction complications?
Death
Arrhythmia
Rupture
Tamponade
Heart failure
Valve disease
Aneurysm
Dressler syndrome (autoimmune pericarditis)
Embolism
Recurrence regurgitation
What is troponin?
A protein complex which regulates actin-myosin contraction and acts as a highly sensitive marker for cardiac muscle injury.
What does elevated troponin indicate?
Higher risk of mortality in patients with suspected ACS
What is the effect of aspirin?
Irreversibly binds to and inactivates cyclo-oxygenase 1 (COX-1), which normally produces prostaglandins and thromboxanes which promote inflammation and clotting. This produces an inhibitory effect on platelet aggregation and so helps to reduce risk of blood clots and myocardial infarction.
What is the effect of P2Y12 inhibitors?
They bind antagonistically to the platelet P2Y12 receptor and prevent the binding of ADP which attenuates platelet aggregation and reaction of platelets to thrombus stimuli such as thrombin.
Give 3 examples of P2Y12 inhibitors
Clopidogrel, Prasugrel, Ticagrelor
What is the effect of GPIIb/IIIa antagonists?
They bind to GPIIb/IIIA receptors on the platelet plasma membrane preventing the binding fibrinogen and von Willebrand factor. This inhibits the aggregation of platelets and formation of thrombi.
Give 3 examples of GPIIb/IIIa antagonists
Abciximab, Eptifibatide, Tirofiban
What is PCI?
Percutaneous coronary intervention describes the combination of coronary angioplasty with stenting.
What is CABG?
Coronary artery bypass graft. A piece of a vein from the leg or artery from the chest is used to create an alternative route for blood flow between the aorta and coronary artery’s when the normal route is blocked.
What is the cause of angina?
Mismatch of oxygen demand and supply.
What are the risk factors of IHD?
- age
- smoking
- family history
- diabetes mellitus
- hyperlipidaemia
- hypertension
- kidney disease
- physical inactivity
- male
- stress
- obesity
What factors exacerbate IHD?
Affecting supply:
- anaemia
- hypoxaemia
- polycythemia
- hypothermia
- hypovolaemia
- hypervolaemia
Affecting demand:
- tachyarrthythmia
- valvular heart disease
- hypertension
- hypertrophic cardiomyopathy
What 4 environmental factors exacerbate IHD?
- cold
- emotional stress
- exercise
- heavy meals
What are differential diagnoses for chest pain?
- myocardial ischaemia
- pericarditis/myocarditis
- pulmonary embolism/pleurisy
- chest infection/pleurisy
- gastro-oesophageal
- musculoskeletal pain
- psychological
- dissection of the aorta
What is pericarditis?
Inflammation of the pericardium
What are the 6 categories for causes of pericarditis?
Viral (coxsackie virus is most common)
Bacterial (TB)
Autoimmune (SLE, Sjorgens Syndrome, RA)
Neoplastic (metastatic lung, breast)
Metabolic
Traumatic and iatrogenic
What are the risk factors for pericarditis?
- male
- age 20-50
- transmural myocardial infarction
- cardiac surgery
- neoplasm
- viral and bacterial infection
What are the key presentations of pericarditis?
- severe, pleuritic, rapid onset chest pain
- pericardial rub
What is the first investigation for pericarditis?
ECG
What is the management of pericarditis?
- sedentary activity until resolution of symptoms and ECG/CRP
- High dose NSAID or Aspirin
- Colchicine (to prevent constrictive pericarditis)
What pathology can be identified using ECG?
- arrhythmias
- myocardial ischaemia and infarction
- pericarditis
- chamber hypertrophy
- electrolyte disturbances (i.e. hyperkalaemia, hypokalaemia)
- drug toxicity (i.e. digoxin and drugs which prolong the QT interval)
What is the normal intrinsic rate of the SA node?
60-100bpm
What is the normal instrinsic rate of the AV node?
40-60 bpm
What is the normal intrinsic rate of the ventricular cells?
20-45 bpm
What is the passage of electrical conduction through the heart?
Sinoatrial node –> AV node –> Bundle of His –> Bundle branches –> Purkinje fibres
What are the significances of the letters in the PQRST sequence?
P wave = Atrial depolarisation
PR interval – time taken for electrical activity to move between the atria and the ventricles (120-200ms)
QRS sequence = Atrial repolarisation (not visible) and Ventricular depolarisation
ST segment – time between depolarisation and repolarisation of the ventricles (ventricular contraction)
T wave = Ventricular repolarisation
What are unipolar and bipolar leads?
unipolar leads = one point on the body and a virtual reference point with zero electrical potential, located in the centre of the heart
- Measures the potential difference (voltage) between an electrode (positive) and a combined reference electrode (negative)
- Sometimes known as augmented leads
bipolar leads = two different points on the body
- Measure the potential difference (voltage) between two electrodes
- One positive and one negative electrode
What is the normal length of the PR interval?
120-200 ms (3-5 little squares)
What is the normal width of the QRS complex?
No more than 110ms (<3 little squares)
In which leads should the QRS interval be dominantly upright?
Leads I and II
In which leads must the P and T waves be upright?
Leads I, II, V2-V6
What psychosocial factors affect CHD?
- behaviour patterns
- depression/anxiety
- social support
- work
Which ECG leads produce an inferior view of the heart?
Leads II, III, aVF
Which leads produce a lateral view of the heart?
I, aVL, aVR, V5, V6
Which leads produce an anterior view of the heart?
V3, V4
What is the most common congenital heart problem?
ventricular septal defect
Which leads produce a septal view of the heart?
V1, V2
What is Prinzmetal’s angina?
Mismatch in blood supply and demand to heart muscle due to coronary vasospasm (atherogenesis) –> seen in cocaine users
* ECG shows ST elevation
What is Eisenmenger’s syndrome?
High pressure pulmonary flow with a VSD so that pressure in the RV is greater and deoxygenated blood enters LV so patient becomes cyanotic (blue) and has clubbing of fingers.
What are the clinical signs for VSD?
Large defect: small breathless skinny baby, increased resp rate, tachycardia, big heart
Small defect: loud systolic murmur, thrill (buzzing sensation), well grown, normal heart rate and size
What are the clinical signs of ASD?
- pulmonary flow murmur
- fixed split second heart sound (delayed closure of PV because more blood has to get out)
- big pulmonary arteries on CXR
- big heart on CXR
What is AVSD?
Atrio-ventricular septal defects - strong association with Down’s syndrome
= hole at the centre of the heart which involves the ventricular septum, the atrial septum, the mitral and tricuspid valves
What is the tetralogy of Fallot?
A combination of 4 congenital heart defects which usually result in a lack of oxygen-rich blood reaching the body.
- pulmonary stenosis
- ventricular septal defect
- dextroposition (heart on the right, apex to the left)
- right ventricular hypertrophy
What is the key issue in tetralogy of Fallot?
Anterior dislocation of the septum below the pulmonary outflow - this results in the other issues.
What is a ‘Fallot spell’
Stenosis of the RV outflow leads to higher pressure in the RV than the LV this causes deoyxgenated blood to enter the right ventricle and makes patient look blue.
What is complete transition of the great arteries (TGA)?
When the aorta comes off the right ventricle and the pulmonary trunk off the left ventricle.
What is coarctation of the aorta?
Narrowing of the aorta just after the arch with excessive blood flow being diverted through the carotid and subclavian vessels into systemic vascular shunts to supply the rest of the body. This occurs as a result of an excessive sclerosing /obliterating process that normally closes the ductus arteriosus, extending into the aortic wall.
What is endocardial fibroelastosis?
Secondary endocardial fibroelastosis is a frequent complication of congenital aortic stenosis and coarctation. Profound dense collagen and elastic tissues deposited on the endocardial aspect of the left ventricle produces progressive stiffening of the heart and cardiac failure.
What is cor pulmonale?
Right ventricular hypertrophy and dilatation due to pulmonary hypertension.
What are the symptoms of a patent ductus arteriosus?
Blood is shunted from aorta to pulmonary trunk which creates risk of pulmonary overload and Eisenmenger’s.
Symptoms: dyspnoea, failure to thrive, machine-like murmur
What is the definition of heart failure?
The inability of the heart to deliver oxygenated blood to tissues at sufficient rate for the tissue’s metabolic requirements.
What are the causes of heart failure?
Most common: Ischaemic heart disease
- cardiomyopathy
- vascular disease
- cor pulmonale
- anything which increases cardiac strain (obesity, pregnancy, arrhythmias, hypertension, hyperthyroidism)
What are the risk factors for heart failure?
Age (65+ yrs)
Smoking
Obesity
Previous MI
Male
african descent
What is the pathophysiology of heart failure?
- Weakened cardiac muscles result in decreased cardiac output
- This activates the compensatory mechanisms of RAAS and SNS which temporarily increase BP as a result of increased aldosterone, ADH and adrenaline/NAd
- Soon compensation fails and heart undergoes cardiac remodelling in response to compensation and cardiac output decreases causing multi-systemic effects.
What are the key manifestations of heart failure?
Shortness of breath, ankle swelling, fatigue
What is the key blood marker in heart failure diagnosis?
Brain natriuretic peptide (BNP) (released from ventricles in response to increased mechanical stress) - the higher the BNP, the more severe the HF
What are the XR findings in heart failure?
Alveolar oedema
Kerley B Lines
Cardiomegaly
Dilation of UPPER lobe vessels
Effusions
What is the most common cause of heart failure
Ischaemia
What is the management for heart failure?
- lifestyle changes
- ACE-i + B-blocker
+ spironolactone + furosemide
What is the definition of hypertension?
Blood pressure ≥140/90mmHg
What are the initiating factors for hypertension? (8)
DRIED ICE
- Disturbance of autoregulation
- Renal sodium retention
- Insulin resistance/hyperinsulinaemia
- Excess sodium intake
- Dysregulation of RAAS with elevated plasma renin activity
- Increased sympathetic drive
- Cell membrane transporter changes
- Endothelial dysfunction
Which medications increase blood pressure?
- NSAIDs
- SNRIs (serotonin and norepinephrine reuptake inhibitors)
- Corticosteroids
- Oral contraceptives (oestrogen containing)
- Stimulants
- Anti-anxiety drugs
- Anti-TNFs
What are the risk factors for hypertension?
- age >65yrs
- moderate/high alcohol intake
- sedentary lifestyle
- FH of hypertension of CAD
- obesity
- metabolic syndrome
- diabetes mellitus
- black ancestry
- hyperuricemia
- obstructive sleep apnoea
** Smoking is NOT a risk factor
what is the equation for BP?
BP = CO x TPR
What factors affect blood pressure?
- Preload
- Contractility
- Vessel hypertrophy
- Peripheral constriction
What are the common symptoms of hypertension?
Most often symptomless.
- headache
- visual changes
- dyspnoea
- chest pain
- sensory of motor deficit
What is the gold standard screening for hypertension?
ECG
What is the management for hypertension?
- Lifestyle modification and monitoring (increase exercise, reduce sodium intake, lose weight)
Medical treatment thresholds: low CDV risk = 160/100mmHg, high CDV risk = 140/90mmHg
- calcium channel blockers, ACEis, ARBs, diuretics, B-blockers
What is aortic stenosis?
Narrowing of the aortic valve.
What are the causes of aortic stenosis?
Congenital: can occur with unicuspid, bicuspid, tricuspid valve and is commonly associated aortic coarctation, dissection or aneurysm
Acquired: degenerative calcification, rheumatic heart disease, rare causes (infectious vegetations, Paget disease, Rheumatoid arthritis)
What is the pathophysiology of aortic stenosis?
Development of a pressure gradient between the left ventricle and aorta (increased afterload).
LV function intially maintained by compensatory pressure hypertrophy but when compensatory mechanism exhausted, LV function declines.