22 Diastolic function of the left ventricle Flashcards
What is diastolic HF?
The presence of symptoms and/or signs of HF but with normal systolic function.
How is diastolic HF defined by the ESC?
LVEF >50%
LVEDVi <97ml/m2
LVESVi <49ml/m2
Describe the pathophysiology of diastolic dysfunction.
In diastolic dysfunction, the increased stiffness, decreased compliance and impaired relaxation of the LV increase LVEDP. This increases LA pressure which causes LA dilatation. This decreases LA compliance and strain. This causes IVC and hepatic vein dilatation and the symptoms and signs of venous congestion.
What are the new routine measures of diastolic function?
E/e’:
In early diastolic function, the E velocity (mitral inflow velocity) and e’ velocity (mitral annular velocity) decrease so the E/e’ ratio is normal. In late diastolic dysfunction, the impaired LV relaxation, which decreases the e’ velocity, and decreased LV compliance, increase the LA pressure, LV filling pressures and E velocity. This increases the E/e’ ratio.
Peak E velocity:
In diastolic dysfunction, the increased LA pressure increases the transmitral pressure gradient. This increases the E velocity.
Septal and lateral e’ and mitral annular TDI:
In diastolic dysfunction, the decreased LV relaxation decreases the e’ velocity and mitral annular TDI.
LA volume (LAVi):
In diastolic dysfunction, the increased LA pressure increases the LA volume.
TR velocity (peak TR velocity):
In diastolic dysfunction, the increased LA pressure increases the pressures in the pulmonary system and causes pulmonary hypertension. This increases RV afterload which causes RV hypertrophy and RV dilatation. This causes tricuspid annular dilatation which increases the TR. This increases RA volume which causes RA dilatation. This causes tricuspid annular dilatation which increases the TR.
LA strain:
In diastolic function, the decreased LV compliance increases the LA pressure. This decreases LA compliance which decreases LA reservoir strain.
What are the new supplementary measures of diastolic function?
L wave:
The L wave is a wave between the E wave (early diastole) and the A wave (atrial systole), in mid diastole, on the MV inflow trace. During mid diastole, the LA pressure and LV pressure are equal and the blood flow from the pulmonary veins into the LA increases the LA pressure. In diastolic dysfunction, the LA compliance is decreased so the blood flow from the pulmonary veins into the LA causes the LA pressure to become greater than the LV pressure so the MV opens and blood flows from the LA into the LV.
PV S/D ratio:
In diastolic dysfunction, the decreased LV compliance increases the LA pressure. The LA pressure is greater than the pulmonary vein pressure during atrial systole which causes more retrograde blood flow from the LA into the pulmonary veins during atrial systole. This decreases the PV S wave velocity. Therefore, the PV D wave velocity is greater than the PV S wave velocity.
PV Ar duration:
The pulmonary vein A wave is the flow of blood, from the LA into the pulmonary veins during atrial systole (end ventricular diastole). In diastolic dysfunction, the decreased LV compliance increases the LA pressure. This causes retrorograde blood flow into the pulmonary veins during atrial systole. This increases PV Ar wave velocity and duration.
MV A duration:
The transmitral A wave is the flow of blood from the LV into the LA during atrial systole (end ventricular diastole). In diastolic dysfunction, the decreased LV compliance increased LVEDP. This increases the LA afterload. This decreases MV A wave velocity and duration.
Describe the use of LA size and LA strain in the assessment of diastolic function.
In diastolic dysfunction, the decreased LV compliance increases the LV pressure. This increases the LA pressure which increases the LA volume. A LV volume of >34ml/m2 indicates diastolic dysfunction.
The increased LA volume decreases the LA compliance which decreases the LA strain. A LV reservoir strain of <30% indicates diastolic dysfunction.
Describe the use of E wave velocity, A wave velocity, E/A ratio and DT in the assessment of diastolic function.
In Mild (grade I) diastolic dysfunction, the E wave (early passive LV diastolic filling) decreases and the A wave (late active LV diastolic filling) increases so the E/A ratio decreases. This is because the impaired LV relaxation decreases LV filling during early diastole. Therefore, to compensate, LA contraction increases to increase LV filling during late diastole. The DT increases. This is because the impaired LV relaxation slows LV filling.
In moderate (grade II) diastolic dysfunction, the E wave increases and the A wave decreases so the E/A ratio increases and normalises. The DT decreases and normalises. This is because the LA pressure increases which increases the LA/LV pressure gradient. This increases LV filling during early diastole and LV filling speed.
In severe (grade III/IV) diastolic dysfunction, the E wave further increases and the A wave further decreases so the E/A ratio increases. The DT further decreases. This is because the LA pressure increases significantly which increases the LA/LV pressure gradient. This increases rapid LV filling during early diastole.
Describe the use of TDI, E wave velocity, e’ velocity and E/e’ ratio in the assessment of diastolic function.
In LV diastolic dysfunction, the E’ (early myocardial velocity) is less than the A’ (late myocardial velocity) so the E’/A’ reverses and the E’/A’ is <1.
The E wave is early diastolic transmitral blood flow velocity. In diastolic dysfunction, the increased LA pressure increases the transmitral pressure gradient. This increases the E velocity.
The e’ is the early diastolic tissue velocity. In diastolic dysfunction, the decreased LV relaxation decreases the e’ velocity and mitral annular TDI.
The E/E’ ratio shows LA pressure and estimates LV filling pressures.
In diastolic dysfunction, the impaired LV relaxation decreases the e’ velocity. The decreased LV compliance increases the LA pressure which increases the E wave velocity. This increases the E/e’ ratio.
Describe the use of IVRT in the assessment of diastolic function.
IVRT is the time between AV closing and MV opening in which the LV relaxes so the LV pressure decreases but the LV volume remains constant.
In mild LV diastolic dysfunction, the IVRT is increased. This is because the LV relaxation is impaired so the time taken for the LV pressure to decrease to below LA pressure is longer. In moderate LV diastolic function, the IVRT is normal (pseudo normal). In severe LV diastolic dysfunction, the IVRT is decreased. This is because the LA pressure increases, to compensate for the decreased LV compliance, so the LV pressure is required to decrease less so the time taken for the LV pressure to decrease to below LA pressure is shorter.
Describe the use of mitral propagation velocity in the assessment of diastolic function.
The Vp is the rate at which the blood flows into the LV.
In diastolic dysfunction, the LV compliance decreases and the LV pressures increase so the Vp decreases.
Vp is used to differentiate normal and pseudo normal E/A patterns.
Describe the use of pulmonary vein flow in the assessment of diastolic function.
S wave (LA into LV during systole). D wave (LA into LV during early diastole). A wave (pulmonary veins into LA during atrial systole).
In diastolic dysfunction, the LV compliance decreases so the LA pressure increases. This decreases the pressure gradient between the pulmonary veins and the LA during systole so the S wave decreases. This also increases the pressure gradient between the LA and the LV during diastole so the D wave increases. This causes systolic flow blunting (S < D).
In diastolic dysfunction, the A wave reversal velocity and duration increase because the LV compliance decreases so the LA pressure increases, during atrial systole. Therefore, the LA pressure is greater than the pulmonary vein pressure during atrial systole. This causes more retrograde blood flow from the LA into the pulmonary veins during atrial systole.
What is pseudo normalisation in diastolic dysfunction?
In moderate (grade II) diastolic dysfunction, the E wave increases and the A wave decreases so the E/A ratio increases and normalises. The DT decreases and normalises. This is because the LA pressure increases which increases the transmitral pressure gradient. This increases LV filling during early diastole and LV filling speed.
MR increases LA pressure which increases LV filling during early diastole. This causes the E wave to increase and the E/A ratio to normalise or increase. This can hide the LV diastolic dysfunction and cause a pseudo normal pattern.
Describe the use of the Valsalva manoeuvre to differentiate normal and pseudo normal patterns.
The Valsalva manoeuvre involves breathing out against a closed airway. This increases intrathoracic pressure which decreases venous return which decreases LA pressure. In LV diastolic dysfunction, the increased LA pressure increases early diastolic LV filling which creates a pseudo normal pattern. The Valsalva manoeuvre decreases the high LA pressure which shows the true impaired LV relaxation pattern in which the E wave decreases, the A wave increases and the E/A ratio reverses to show the true LV diastolic dysfunction. The Valsalva manoeuvre differentiates between normal and pseudo normal patterns because, in patients with true normal patterns, the pattern is normal at rest and stress, but in patients with pseudo normal patterns, there is a normal pattern at rest but a decreased E wave and an increased A wave with the Valsalva manoeuvre.
