Session 1 ILO's Flashcards
Describe the anatomy of the heart and it’s position in situ (14)
- 2 Atria (left and right)
- 2 Ventricles (left and right)
- 4 Valves (Right: Pulmonary and Tricuspid, Left: Aortic and Mitral)
- Interatrial septum divides the heart into right and left atrium
- Interventricular septum divides the heart into right and left ventricles
- Atrioventricular valves separate the atrium from the ventricles (e.g. tricuspid valve, made of 3 leaflets and mitral valve, made of 2 leaflets)
- Semi-lunar valves separate ventricles from arteries (e.g. pulmonary valve, made of 3 leaflets and aortic valve made of 2 leaflets)
- Valve problems may cause turbulent blood flow so you will hear murmurs through the stethoscope
- Common misconception that atria are above ventricles, but in reality, they are behind them
- Heart and vessels contained within it’s protective jacket of pericardium
- Lies in the middle mediastinum
- Within the thorax, closer to the midline as opposed to far left
- Apex faces the left The apex beat should normally be felt in the 5th intercostal space at the mid-clavicular line.
- Heart behind sternum and directly above diaphragm
Be aware of different imaging techniques that can be used to assess cardiac structure and functioning (5)
- X-ray
- Nuclear
- Ultrasound - Transesophageal Echocardiogram (used in first line imaging of valve disease)
- CMR (Cardiac MRI)
- CT (Cardiac computed tomography)
State the normal cardiac output for an average adult male at rest
Cardiac Output = Heart Rate x Stroke Volume
5L/min
Relate plain film AP X-ray of chest to the structures in the thoracic cavity (11)
- Weak points:
- Right atrium
- Left atrium
- Left ventricle
Calculate the cardiac / thoracic ratio and suggest what an increased ratio might mean
- Ensure you have a PA view
- Vertical line from start of thoracic cavity to level of diaphragm
- Measure the max extension of left side of line of heart
- Measure the max extension of right side of line of heart
- Add together to get diameter of heart
- Make another measurement - max diameter or thoracic cavity
- Thoracic diameter divided by heart diameter will give you the CR
An increased ratio (a ratio of more than 0.5) might mean abnormal enlargement of heart - cardiomegaly
Patient has cardiac disorder
E.g. dilated left ventricle, ventricular hypertrophy, pericardial effusion which has built up over some considerable time
The heart might also be abnormally small - COPD (Chronic Obstructive Pulmonary Disease)
Identify coronary arteries from 2D or 3D coronary angiograms
Describe the function of the pericardium (4)
Function:
- Prevents excessive movement of the heart within thoracic cavity
- Prevents excessive filling of heart
- Encloses heart and root of great vessels - aorta and pulmonary trunk
- Helps protect heart
Describe the structure pericardium, it (5)
- 2 Layers - Outer fibrous and inner serosal
- Inner serosal consists of visceral pericardium layer (epicardium), which adheres to the external wall of heart and parietal pericardium layer which lines the inside of the outer fibrous layer
- Pericardial cavity is the space between visceral and parietal layers. It consists of pericardial fluid, which reduces friction
- Superiorly, the vessels that emanate from the pericardium are: aorta, pulmonary artery, superior vena cava
- Inferiorly, the vessels that emanate from the pericardium are: inferior vena cava
Describe the problems associated with accumulation of fluid in the pericardial sac (6)
- Too much fluid = pressure = prevents pumping properly = compression = cardiac tamponade
- Pericardial effusion is the build up of extra fluid in the space around the heart
- If too much fluid builds up, due to the inextensible fibrous pericardial layer, it can put pressure on the heart
- This can prevent it from pumping properly so it gets compressed
- Compression of the heart can lead to cardiac tamponade as the heart cannot fill during diastole
- Excess fluid can be removed for testing or to relieve compression
- Pericardiocentesis is the procedure to remove excess fluid
Describe the relationship of the pericardium to the phrenic nerves (4)
- Pericardium is innervated by phrenic nerve
- Phrenic nerve provides touch and pain sensory innervation to pericardium
- Pericardium separates right phrenic nerve from right atrium
- It also separates left phrenic nerve from left pulmonary artery, left atrium and left ventricle
Describe the course of blood flow into and out of the heart through the major vessels
Explain how blood flow is controlled and how appropriate blood flow to different tissues of the body is achieved
- Arterioles control the flow of blood
- You can send more blood to where you need it and divert blood away from where you don’t need it
- The systems that need more blood produce various metabolites that cause vasodilation in the arterioles (e.g. temperature, potassium, co2, lactic acid and adenosine increase, oxygen decrease)
- As these arterioles for the system dilate, it causes constriction of arterioles else where
- This is mediated by the sympathetic nervous system
Describe the constituents of whole blood
- Plasma
- WBC and platelets (Buffy coat)
- RBC
Fluid collected from clotted blood = serum
Fluid collected from unclothed blood = plasma (plasma contains fibrinogen - main clotting factor in body)
Describe the effect of changing cell number or protein content on viscosity of whole blood
You will get an increase in viscosity, causing thick, sludge blood
Describe some conditions which affect the cell count or protein content of blood.
- Multiple myeloma (cancer of plasma cells so at the build up of plasma cells increases viscosity)
- Leukemia (increase in white blood cells)
- Polycythaemia (increase in RBC)
- Thrombocythaemia (increase in platelets)
- Inflammation (CRP may increase)
Describe how arterial blood pressure is measured and what would be heard in a stethoscope as the pressure in the cuff is changed
Blood pressure is usually silent because flow is laminar
- Inflate cuff around upper arm whilst palpating the radial pulse [1 mark]*
- Inflate to 30mmHg above the point where the pulse disappears [1 mark]*
- Release pressure slowly, listening with stethoscope over brachial artery [1 mark]*
- First Korotkoff sound = systolic pressure [1 mark] Fifth Korotkoff sound (where sounds disappear) = diastolic pressure [1 mark]*
- Increase pulse pressure
- Occludes the brachial artery = NO FLOW = silent - Gradually reduce cuff pressure
- Some blood flow but it’s TURUBLENT FLOW = can hear Korotoff sounds
- Start of systole - Reduce cuff pressure further until cuff pressure < artery pressure = NORMAL FLOW = silent again
- Start of diastole
Or you can doit manually with a sphygmomanometer
Describe factors that will effect venous pressure and factors that will affect arterial pressure
Arterial and venous pressure affected by:
- Cardiac output
- Total peripheral resistance
If TPR falls and CO is unchanged:
- Arterial pressure will fall and venous pressure will increase
If TPR increases and CO is unchanged:
- Arterial pressure will Increase and venous pressure will fall
If CO increases and TPR is unchanged:
- Arterial pressure will Increase and venous pressure will fall
If CO decreases and TPR is unchanged:
- Arterial pressure will fall and venous pressure will rise
