9 Cardiac functional parameters Flashcards
What are the advantages and disadvantages of M-mode?
M-mode offers a high temporal resolution.
MAPSE and TAPSE only assess the ventricular longitudinal systolic function, not the radial function or diastolic function. Aortic and LA dimensions assume symmetric geometry.
How are SV, EF, RWT, LV mass and LV mass indexed calculated?
SV is the volume of blood ejected by the heart in one beat.
SV = EDV – ESV
EF is the percentage of blood ejected by the heart in one beat.
EF = SV / EDV x 100
RWT differentiates the types of hypertrophy.
RWT = (2 x LVPWd) / LVIDd
LV mass uses LV wall thickness and LV internal diameters to estimate the LV mass. LV mass differentiates the types of hypertrophy.
LV mass indexed = LV mass / BSA.
What are the 2D and 3D methods to measure LV volume and what are the limitations of 2D?
The 2D method (the Simpon’s biplane method) estimates the LV mass by diving the LV into discs and adding the discs.
The 3D method directly measures the LV mass.
The 2D methods are less accurate because they assumes that the LV is uniform and ellipsoid so are not accurate in patients with abnormal LV geometry.
What are the 2D and 3D methods to measure LVEF and what are the limitations of 2D?
The Teicholtz formula estimates LVEF, via a single plane, and the Simpon’s biplane method estimates LVEF, via two planes, but both assume symmetric LV geometry.
The advantages of 3D are increased accuracy (because of the absence of assumptions about LV geometry), increased reproducibility (in patients with abnormal LV geometry) and improved LV function assessment (uses all views and is more accurate in patients with RWMAs).
How do poor quality images affect assessment?
Images with low resolution and/or artefacts can cause inaccurate measurements and off axis images can skew measurements. This can cause underestimation or overestimation of size and/or function.
How are velocities, gradients and PHT used to assess valves?
Use CWD to measure velocities. Increased velocities indicate stenosis and decreased velocities indicate regurgitation.
Use the Bernoulli equation to calculate gradients. Increased gradients indicate stenosis.
PHT is the time taken for the pressure gradient to decrease to half of its original value. Shorter PHTs indicate regurgitation.
How are the E/A, DT, pulmonary vein flow, E/E’ and Vp used to assess diastolic function?
The E/A ratio is the ratio of early to late LV filling velocities. An increased E/A ratio indicates diastolic dysfunction.
DT is the time taken for the E wave to decelerate from peak to baseline. A decreased DT indicates diastolic dysfunction.
Pulmonary vein systolic blunting or systolic flow reversal indicate increased LA pressures and diastolic dysfunction.
The E/E’ is the ratio of diastolic transmitral velocity to diastolic myocardial velocity. An increased E/E’ indicates diastolic dysfunction.
The Vp is the velocity of the early diastolic mitral inflow into the LV. A decreased Vp indicates diastolic dysfunction because the LV is less compliant.
How do doppler and catheterisation derived gradients differ?
CWD measures estimates gradients, via the Bernoulli equation.
Catheterisation directly measures gradients but is invasive.
How is pulmonary hypertension assessed using PASP?
PASP = RVSP = 4 x (TR Vmax)2 + RAP. A PASP of >25mmHg indicates pulmonary hypertension.
