Cardiac Imaging Flashcards
how would stable angina be investigated?
- non-invasive modalities (anatomical)
- invasive modalities (functional)
- coronary angiography
what are the most common cardiac imaging tests?
x ray
electrocardiogram
echocardiogram
cardiac MRI
when is a patient referred for a chest X ray?
- chest pain
- discomfort
- tightness
- breathlessness
what could be seen on a heart failure chest X ray?
-pleural effusion
-cephalization of vessels
-Kerley B lines
-increased cardio thoracic ratio - can see cardiomegaly seen by increased cardiothoracic ratio
- can see signs of oedema - a condition characterised by an excess of watery fluid in cavity
- upper venous diversion depicted by the green arrows
- Important to notice any additional cardiac structures like metallic valves and external wires which are visible in the patient suggesting this patient had previous cardiothoracic surgery
what questions can a echocardiogram answer?
-do the ventricles work
-is there significant heart disease
what indications can be seen on an echocardiograms?
- structural imaging of the left or right ventricle and their cavitiesthis would be to evaluate ventricular hypertrophy, dilation, or wall motion abnormality; to visualise thrombi
- structural imaging of the valvesthis would be to evaluate regurgitations, aortic stenosis and mitral valve prolapse
- structural imaging of the pericardiumthis would be to exclude pericardial effusion
- structural imaging of atria and septa between cardiac chambers
- structural imaging of the greatest vesselsthis would be to see aortic dissection
why do we use many 2D planes on an echocardiogram?
as we are taking an image of a 3-D structure but only from 2 dimensions we must look at this 3-D structure from multiple angles
what planes are used on an echocardiogram?
left parasternal long axis view
short axis view, aortic valve view
apical four chamber view
what are the most noticeable structures on the left parasternal long axis view?
- left atrium
- left ventricle
- aortic arch
- mitral and aortic valves
- sometimes papillary muscles can be seen
how can we get a short axis view?
rotate the probe 90 degrees
what can we see on a short axis view?
- left ventricle
- right ventricle
- anterior and posterior papillary muscles
- anterior wall
what is a short axis view, arortic valve view?
further up from that view get a cross-section with the aortic valve in the middle of the picture and the right ventricle wrapped around it
what can be seen on an apical 4 chamber view?
all four chambers
what can we see on a dilated cardiomyopathy echo (long axis view)?
left ventricle is dilated and not contracting very well
how can you check for left ventricular ejection fraction on a 2D echocardiogram?
- You must look at the heart from two different views
1. 4 chamber
2. 2 chamber - ( use both short and long view ) which both involve 90 degree rotation
- measure the dimensions of the left ventricle in these two views in diastole and systole
what is an echo doppler?
use ultrasound technology to generate colour flow mapping as well as measure the velocity of blood going across valves
what does aortic stenosis look like on a echocardiogram?
- parasternal long axis view
- aortic valve has thickened and white which suggests its calcified doesn’t open well
- aortic valve in the middle
what does aortic stenosis look like on an echo doppler?
- velocity time graphs - velocity is vertical, time is horizontal
- can see the velocity of blood accelerated at 4m/s
- ratio taken from the velocity in the aortic valve and the velocity in the left ventricular outflow tract
- ratio would show significant aortic stenosis
what is aortic regurgitation?
aortic valve doesn’t close properly
how do we prep for a Transoesophageal echocardiography?
- patient is given conscious sedation,
- back of throat is numbed,
- bite guard is placed so patient doesn’t bite the probe
how is a TEE carried out?
probe is advanced as the patient swallows and it goes down until its behind the left atrium
what indications does a TEE give?
to assess valve function (important with prosthetic valves as well as assessment of infective endocardiatis
how does cardiac MRI work?
- uses magnetic fields and the protons and hydrogen ions within the body tissue to generate imaging
- takes 45-60 minutes
why are cardiac MRIs important?
don’t need ionising radiation to generate the pictures
what indications can a cardiac MRI give?
- reference for standard LV and RV volume
- ischaemic heart disease
- heart failure assessment
- myocardial tissue characteristion
- valvular heart disease
- adult congenital heart disease
what are the negatives of cardiac MRI?
- expensive
- lengthy examination time
- patient cooperation (breath hold)
- claustraphobia
- contra- indications (metal)
what is cardiomyopathy?
walls of the heart chambers have become stretched, thickened or stiff
what is late gadolinium enhancement?
a method where cardiovascular magnetic resonance (CMR) images are obtained after the administration of gadolinium contrast material that accumulates into a tissue with increased extra cellular space
what can be seen on imaging mid wall late gadolinium enhancement?
Here, there is a mid wall hyper-enhanced region (at yellow arrows)
Indicative of idiopathic dilated cardiomyopathy
Dilated cardiomyopathy isa type of heart muscle disease that causes the heart chambers (ventricles) to thin and stretch, growing larger
Dilated cardiomyopathy makes it harder for the heart to pump blood to the rest of the body
what is a computed tomography of the coronary arteries (CTCA)
to take pictures of the coronary arteries
how does CTCA work?
- liquid contrast agent containing iodine is injected into a vein
- the iodine increases the density of the blood in the vessels allowing for the inside and outside of the blood vessels to be seen
- beta blockers are given to slow down heart rate
allowing scanner to gather images during diastole
what is a stress test?
aim to prove or exclude inducible ischaemia in the myocardium
how is a stress test carried out?
- with exercise
- with drugs (Dobutamine, Atropine/dipyridamole, Adenosine/regadenoson)
what is an exercise tolerance test?
- cheap to carry out
- in low risk patients (male under 30, female under forty)high chance of a false positive
- in high risk patients (over 50, typical angina)negative test cant rule out coronary artery disease
what are the c
how is a stress echo done?
-drugs or exercise used
-spots problems early on in the ischemia cascade w
what are we testing for in a stress echo?
want to see wether the left ventricle has contractility at peak stress
what is a rest scan?
- involves injection of a radionuclide like thallium 201, technetium-99 sestamibi/ tetrofosmin
- 1 hour
- camera will take images of the heart from different views
what can be seen on a positive exercise ECG?
- positive symptomatically
- positive blood pressure drop
- positive with st depression or elevation
what is a stress scan?
- stress scan
- patient is given adenosine as a transfusion
- this is a pharmacological stress test
- delay of one hour then picture’s acquired using gamma camera
- areas with good blood flow will take up radioactive isotopes
- areas with reduced blood flow will not take up as much of the tracer
what is a coronary angiography?
Coronary angiography is a procedure that uses contrast dye, usually containing iodine, and x ray pictures to detect blockages in the coronary arteries that are caused by plaque buildup.
What is cardiac ratio?
The horizontal distance that the heart takes up divided by the total horizontal distance of the chest cavity
