Cardiology Flashcards
What are the outcomes of an atherosclerotic plaque?
- Occlusion
- Rupture
Give three conditions that are principally caused by atherosclerosis.
- Heart attack
- Stroke
- Gangrene
Give seven risk factors for atherosclerosis.
- Age
- Tobacco smoking
- High cholesterol
- Obesity
- Diabetes
- Hypertension
- Family history
In which arteries are atherosclerotic plaques found?
Coronary and peripheral arteries
What is the ultimate initiating factor for atherogenesis?
Endothelial cell damage
What is a neointima?
Scar tissue in blood vessels which thickens the vessel wall.
Altered gene expression in which four cell types contributes to atherogenesis?
- Endothelial cells
- Macrophages
- Smooth muscle
- Fibroblasts
Give four components of atherosclerotic plaque structure.
- Lipid
- Necrotic core
- Connective tissue
- Fibrous cap
Give seven inflammatory cytokines involved in atherosclerotic plaque formation.
- IL-1
- IL-6
- IL-8
- IFN-y
- TGF-b
- MCP-1
- CRP
How does modified LDL cause inflammation in an arterial wall?
It accumulates in the arterial wall and undergoes oxidation and glycation.
What two things cause inflammation in arterial walls, leading to atherogenesis?
- Modified LDL
- Endothelial dysfunction
What 2 factors mediate leukocyte adhesion to the arterial wall in atherogenesis?
- Selectins
- Integrins
Name the four stages of atherogenesis.
- Fatty streaks
- Intermediate lesions
- Fibrous plaques / advanced lesions
- Plaque rupture
What age do fatty streaks first appear?
<10yrs
Describe the histology of fatty streaks.
Aggregations of lipid laden macrophages and T lymphocytes.
Describe the components of intermediate atherosclerotic lesions.
- Foam cells (lipid-laden macrophages)
- Vascular smooth muscle cells
- T lymphocytes
- Adhesion of platelets to wall
- Pools of extracellular lipid
Describe the formation of the fibrous cap of an atherosclerotic plaque.
Smooth muscle cells migrate to the surface of the plaque and secrete collagen and elastin.
How is the fibrous cap of an atherosclerotic plaque maintained?
Has to be resorbed and redeposited.
How does the fibrous cap weaken, leading to atherosclerotic plaque rupture?
Macrophages secrete matrix metalloproteinases.
Apart from plaque rupture, give one other process that can cause thrombus formation related to an atherosclerotic plaque.
Plaque erosion.
Give six conditions that the ECG can identify.
- Arrhythmias
- Myocardial ischaemia/infarction
- Pericarditis
- Chamber hypertrophy
- Electrolyte disturbances
- Drug toxicity (digoxin)
What is the dominant pacemaker of the heart, and at what rate does it work?
SA node
60-100bpm
What are the two back-up pacemakers of the heart and what rate do they work at?
- AV node, 40-60bpm
- Ventricular cells, 20-45bpm
What is the standard paper speed in an ECG?
25mm/s
What is the amplitude in an ECG?
0.1mV/mm
What are the small and large boxes worth horizontally on an ECG?
Small box = 0.04s
Large box = 0.20s
What is one large box worth vertically on an ECG?
0.5mV
Why doesn’t atrial repolarisation show up on an ECG?
It is masked by ventricular depolarisation (QRS complex).
What are the bipolar ECG leads?
I, II, III
What is the J point on an ECG?
The point where the S wave becomes the ST segment.
What do unipolar leads compare on an ECG?
One point on the body and a virtual reference point with zero electrical potential, located in the centre of the heart.
What axis does aVL measure?
-30
What axis does lead I measure?
0
What axis does lead II measure?
+60
What axis does aVF measure?
+90
What axis does lead III measure?
+120
What axis does aVR measure?
-150
Which ECG leads give a lateral view of the left ventricle?I?
- I
- aVL
- V5
- V6
Which ECG leads give an inferior view of the left ventricle?
- II
- III
- aVF
Which ECG leads give a septal view of the left ventricle?
- V1
- V2
Which ECG leads give an anterior view of the left ventricle?
- V3
- V4
How long should the PR interval be?
0.12-0.20s (3-5 little squares)
How long should the QRS complex be?
Shouldn’t exceed 0.12s (3 little squares)
In which leads should the QRS complex be dominantly upright?
I and II
How does the direction of the T wave compare to the QRS complex in limb leads.
Should be same general direction.
In which ECG lead are all the waves negative?
.aVR
How does the R wave change in the chest leads of an ECG?
Grows from V1 to at least V4.
V5>V6
How does the S wave change in the chest leads of an ECG?
Grows from V1 to at least V3.
Disappears in V6.
How should the ST segment appear on an ECG?
And which leads are the exceptions?
Start isoelectric.
Except in V1 and V2
In which leads should P waves be upright?
I, II, V2-V6
Which leads should feature no Q waves (or Q waves <0.04s)?
I, II, V2-V6
In which ECG leads should the T wave be upright?
I, II, V2-V6
What should the amplitude of the P wave be?
<2.5 small squares
In which ECG lead is the P wave commonly biphasic?
V1
Which lead is the P wave best seen in?
II
How are the P waves altered in right atrial enlargement?
What is the ‘official’ name for this?
Tall, pointed P waves.
P Pulmonale
How do the P waves differ in left atrial enlargement?
What is the ‘official’ name for this?
‘M’ shaped P waves.
P Mitrale
What does the Q wave represent?
Left to right bundle branch depolarisation
What does the R wave represent?
Septal depolarisation
What does the S wave represent?
Purkinje depolarisation
Describe the appearance of a normal T wave.
First half has a more graduated slope than the second.
How long should the QT interval be?
0.35-0.45s
What do U waves represent on an ECG?
Related to after depolarisations which follow repolarisation.
How can you determine the regular heart rate using an ECG?
300/number of big boxes between QRS complexes
How can you determine the irregular heart rate on an ECG?
Number of QRS complexes on the rhythm strip x 6
What is the normal heart axis?
-30 to +90
What is a left axis deviation?
-90 to -30
What is a right axis deviation?
+90 to +180
If the QRS complex is positive in lead aVF and Lead I, what is the heart axis?
Normal
If the QRS complex is negative in aVF and positive in Lead I what is the heart axis?
Left axis deviation
If the QRS complex if positive in aVF and negative in lead I what is the heart axis?
Right axis deviation
If the QRS complex is negative in both aVF and lead I what is the heart axis?
Indeterminate axis
How can the equiphasic approach be used to determine heart axis?
Identify most equiphasic QRS complex.
See if QRS complex is positive or negative in the lead at a right angle.
Describe the waves in V1 and V6 for a left bundle branch block.
W in V1
M in V6
Describe the waves in V1 and V6 in right bundle branch block.
M in V1
W in V6
What is the major component of an arterial thrombus?
Platelets
What ‘colour’ is an arterial thrombus?
White
Give four conditions that arise from arterial thrombosis.
- Myocardial infarction
- Stroke
- Cerebrovascular event
- Peripheral vascular disease
What is the major component of a venous thrombus?
Fibrin
What ‘colour’ is a venous thrombus and why?
Red, because the fibrin mesh traps red blood cells.
Give five genetic causes of venous thrombosis.
- Factor V Leiden
- PT20210A
- Antithrombin deficiency
- Protein C deficiency
- Protein S deficiency
What are three acquired causes of venous thrombosis?
- Anti-phospholipid syndrome
- Lupus anticoagulant
- Hyperhomocysteinaemia
How does heparin work?
Binds to antithrombin to increase activity.
What is the normal INR?
<1.1
What is the INR target for people on anticoagulants?
2-3
How is heparin administered?
Continuous infusion
How is low molecular weight heparin administered?
Subcutaneous injection
How does aspirin work?
Irreversibly inhibits cyclo-oxygenase
How long does aspirin work for?
The lifetime of the platelet (7-10days)
How does clopidogrel work?
Blocks platelet P2Y12 ADP receptor.
Name three P2Y12 ADP receptor inhibitors.
- Clopidogrel
- Ticagrelor
- Prasegrel
Give three oral anticoagulants.
- Aspirin
- Warfarin
- DOAC
How does warfarin work?
It is a vitamin K antagonist which prevents synthesis of clotting factors II, VII, IX, and X.
Describe the half life of warfarin.
Long (36 hours)
Which clotting factors do direct oral anticoagulants (DOAC) act on?
II or X
Why can’t DOACs be used in pregnancy?
They can cross the placenta.
Why are DOACs better than warfarin?
They don’t need monitoring.
Give seven conditions that hypertension is a major risk factor for.
- Stroke
- Myocardial infarction
- Heart failure
- Chronic renal disease
- Cognitive decline
- Premature death
- Atrial fibrillation
What blood pressure measurement leads to suspected hypertension?
140/90mmHg
Give three targets for therapy in hypertension.
- Cardiac output / peripheral resistance
- RAAS/SNS
- Vasoconstrictor/dilators