Ch 4 Principles of Regurg Flashcards
(37 cards)
What causes valvular regurg?
-Congenital or acquired abnormalities of the valve leaflets
or
-Abnormalities of associated structures
List 2 abnormalities of associated structures that could cause valvular regurg?
-Dilation of Asc Ao or Ao sinuses, which results in AR with normal valve leaflets
-Dilation of LV, which results in MR with normal leaflets + chordae
Severe regurg lesions occur in what 4 etiologies?
-Large perforations
-Large flail segments
-Profound retraction of leaflets leaving a coaptation gap
-Tenting of leaflets with tethering + loss of coaptation (occurs during pap muscle displacement + annular dilation)
If TTE images are not diagnostic for the evaluation of the AoV or MV + we can not identify the cause of regurg, what type of imaging can be used?
TEE imaging is appropriate if needed for clinical decision making
What causes type 1, 2 + 3 moderate-severe MV regurg?
Type 1 (normal leaflet motion):
-Annular dilation
-Perforation
Type 2 (excessive leaflet motion)
-Prolapse
-Flail
Type 3 (restricted leaflet motion)
-Thickening/fusion
-LV/LA dilation
(note these mechanisms can occur in other valves)
What does EROA stand for?
Effective regurgitant orifice area (this is the size of the hole in the incompetent valve)
List 5 fluid dynamics that occur with valvular regurg?
-EROA
-High velocity regurg jet
-Prox flow convergence region
-Downstream flow disturbance
-Increased antegrade flow volume
Chronic valvular regurg leads to what?
Progressive volume overload of the ventricle
List 3 SF’s when there is volume overload of the LV?
-LV chamber increases in size with normal wall thickness
-Total LV mass is increased
-Irreversible decrease in systolic function (know this)
An important clinical feature of chronic LV volume overload is what?
An irreversible decrease in systolic function, as this can occur w/o symptoms
What is total stroke volume?
Total volume of blood pumped by the ventricle on a single beat
What is forward stroke volume?
Amount of blood delivered to the peripheral circulation
(ex. blood moving from LV into Ao)
What is regurgitant volume?
Amount of backflow across the abnormal valve
(ex. blood moving back into the LA when the MV is closed)
What is the equation for total stroke volume?
Total SV = forward SV + regurgitant SV
CD imaging is based on the identification of what when assessing for regurg?
Identification of flow disturbance downstream from the regurgitant orifice
How accurate is CD at in detecting regurg?
-Extremely sensitive (>90%) + specific (~100%)
-It is so sensitive that regurg is often detected with CD, that is not even audible by auscultation (by a stethoscope)
When would false-positives + false-negatives occur when using CD to detect regurg?
False-positive:
-occurs when the origin or timing of flow signal is mistaken
False-negative:
-occurs when the signal strength is low due to poor acoustic access or attenuation
-can also be due to incorrect CD settings
-can also be due to failure to interrogate the regurg from more than 1 tomographic plane
How can we detect regurg with CW doppler?
-Based on detection of a high velocity jet through the regurg orifice
-By identifying the velocity, shape, timing + associated antegrade flow of the regurg signal (this is critical to interpret the signal correctly)
How can we differentiate LVOT + MR waveforms on doppler?
Both occur in systole, so we must pay attention to the waveforms
LVOT:
-shorter + pointy waveform
-only occurs during ejection
MR:
-longer + round waveform
-occurs from the onset of IVCT + ends at IVRT
What defines physiologic regurg?
-Spatially restricted to the area immediately adjacent to the valve closure
-Short in duration
-Represents only a small regurg volume
List 6 methods to quantify regurg severity?
-CD imaging
-CW doppler
-Vena contracta width
-PISA (proximal isovelocity surface area)
-Volume flow at 2 sites
-Distal flow reversals
(see chart in lecture slides)
Regurgitant severity is based on what?
-The size of flow disturbance in the chamber receiving the regurg jet
-No longer used to grade regurg (is inaccurate b/c there is overlap in jet areas b/w pt’s with moderate + severe regurg)
-Clinically helpful for detecting valve regurg, timing of flow + cause of regurg
List the recommended settings for CD imaging?
Nyquist limit/scale: set b/w 50-70 cm/s
CD gain: set just below the random speckling from nonmoving targets
Have max FR: narrow sector width, decrease depth
Use a higher probe frequency: this creates a higher doppler shift at lower velocities, making jets look larger
What 2 general factors affect regurg jet size + shape?
-Physiologic factors
-Technical factors
(see chart in slides)
