1. The subcostal view 2. IVC 3. Additional subcostal views Incredibly versatile TTE view especially in ventilated patients but is trickier than it seems But first - Hand movements!
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So what are we looking at:
3/10 Labelled subcostal image
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Optimise your image as always: 1. Depth 2. Width 3. Gain 4. Focus
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What can the basic subcostal image tell us?
1. RV size - The 'safety net view' - If you think the RV is dilated in suboptimal PLAX or 4Ch views -> the subcostal view will tell you what you need! (2/3 size of LV) 2. RV free wall motion 3. LV function
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Now for the IVC 90 degree anticlockwise turn It is very easy to make mistakes when it comes to IVC measurement and variation, and mistaking it for descending aorta Must see: 1. IVC - leading edges of vessel 2. Hepatic vein 3. IVC entering RA
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Measuring the IVC 1. Make sure it is the IVC(not aorta!) 2. 'Clean edges' 3. 1cm prox to where hepatic vein joins IVC 4. Beware the moving IVC when assessing response during the respiratory cycle 5. M-mode can be used but ensure cursor perpendicular
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Additional Subcostal views:
RVOT - useful for VTI variability We will go into their use in more detail in subsequent tweetorials
9/10 Subcostal SAX: When the PSAX view is difficult try this: It is very useful indeed!
How do they calculate: 1. Valve area 2. Mean AV gradient 3. Max AV gradient
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Essential Principles: 1. The effective orifice area is always smaller than the anatomical orifice area
This effective orifice area is what is calculated
It is the key determinant of survival 2. Continuity equation
Conservation of mass
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Continuity equation:
A2 X V2 = A1 x V1
(AVA) x (AV VTI) = (LVOT CSA) x (LVOT VTI)
AVA = [(LVOT CSA) x (LVOT VTI)]/ AV VTI
And for those of you who still auscultate the precordium you would have heard the elusive 'tumour plop'....of course you would.
But lets get back to the basics of M- Mode use in the PLAX view
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Firstly the AV:
Here is a normal m-mode image through the AV during the cardiac cycle - note: 1. How systole and diastole are identified by ECG 2. Opening of the RCC and NCC to form the 'envelope' 3. Symmetry of the envelope 4. Closure line at end syst.
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Compare this to m mode in severe AS where there is no identifiable opening of the cusps:
1 Welcome to #researchmethodologies with @DrAoifeBee
Kaplan-Meier (KM) curves are a wonderfully informative way of presenting survival outcomes over time. But how do we interpret them? Survival analysis determines the probability of a binary outcome (aka an event or a failure)
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Survival means the event being studied has not occurred yet - the patient is still alive if you’re analysing mortality, the baby has not been delivered if analysing births, the patient has not yet met whatever criteria you have decided constitutes an event in your study.
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In medical research, the binary outcome of interest is commonly survival vs death though other outcomes/events can be used. KM curves are a visual way of showing the fraction of patients living over time after a treatment, or lack of treatment if in a control group.