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CARDIOVASCULAR JOURNAL OF AFRICA • Volume 29, No 1, January/February 2018
AFRICA
27
of all-cause mortality.
12
Diastolic filling abnormalities may also
play a significant role in the pathogenesis of pulmonary oedema,
complicating hypertensive crises in pregnancy.
13
Desai
et al.
found that diastolic filling abnormalities were
demonstrated in a significant proportion of pre-eclamptic
pregnancies complicated by pulmonary oedema compared
to control groups of women who were hypertensive and
normotensive in pregnancy.
13
The authors of this study postulated
that the diastolic filling abnormalities demonstrated in the study
occurred within a short time frame of severe pre-eclampsia in
pregnancy or could represent pre-eclampsia superimposed on
established hypertension.
Whether diastolic dysfunction persists after delivery is
uncertain.Identifyingfactorsthatmayaffectfuturecardiovascular
risk may identify a group of women requiring increased post-
partum vigilance and lifestyle modification. The aim of this
study was to determine cardiac diastolic function at delivery and
one year post-partum in women with severe pre-eclampsia and
to further determine possible future cardiovascular risk.
Methods
This was a descriptive study of women with severe pre-eclampsia,
performed at Steve Biko Academic Hospital from 1 April 2013
to 30 March 2016. The Cardiology Department at Steve Biko
Academic Hospital reserved echocardiographic appointments
every Wednesday during the study period. Post-partum women
with severe pre-eclampsia were identified on a Wednesday
morning and if fit to be transported to the cardiology clinic,
were informed of the study. Echocardiographic studies were
performed on patients who consented to the procedure and were
agreeable to follow-up studies.
One hundred and six women with severe pre-eclampsia and 45
normotensive, low-risk women who served as the control group
were identified and recruited shortly after delivery. Women with
structural heart disease or pulmonary embolus were excluded
from the study. Women diagnosed with maternal metabolic
syndrome were not recruited to the control group.
Echocardiograms of the maternal heart were performed
between day two and seven post-delivery and follow-up scans
were done after one year. Hypertensive disorders were classified
according to the classification and diagnosis of the International
Society for the Study of Hypertension in Pregnancy (ISSHP).
14
Doppler echocardiography was carried out by the Department
of Cardiology at Steve Biko Academic Hospital. The following
echocardiographic parameters were assessed in the evaluation of
diastolic dysfunction: left ventricular ejection fraction (LVEF),
mitral E-wave (E) and mitral A-wave velocities (A), E/A ratio,
mitral E-velocity deceleration time (DT), lateral early diastolic
(e
′
) velocity tissue Doppler and E/e
′
ratio.
The diagnosis of diastolic dysfunction was made by a clinician
in the cardiac-obstetric unit. All women diagnosed with diastolic
dysfunction had the following minimum positive criteria: average
E/e
′
>
14 and lateral e
′
velocity
<
10 cm/s. The American
Society of Echocardiography and the European Association
of Cardiovascular Imaging have described the advantages and
limitations used to assess left ventricular diastolic function
15
(Table 1).
Table 1. Utility, advantages and limitations of variables used to assess left ventricular diastolic function
15
(reproduced with permission)
Variable
Physiological background
Advantages
Limitations
Mitral E velocity Reflects the LA–LV pressure gradient during
early diastole and is affected by alterations in
the rate of LV relaxation and LAP
Feasible and reproducible
Directly affected by alterations in LV volumes
and elastic recoil. Age dependent
Mitral A velocity Reflects the LA–LV pressure gradient during
late diastole, which is affected by LV compliance
and LA contractile function
Feasible and reproducible
Sinus tachycardia, first-degree AV block and
paced rhythm can result in fusion of the E and A
waves. If mitral flow velocity at the start of the
atrial contraction is
>
20 cm/s, A velocity may be
increased.
Age dependent
Mitral E/A ratio Mitral inflow E/A ratio and DT are used to
identify the filling patterns
Feasible and reproducible.
Provides diagnostic and prognostic
information. A restrictive filling pattern in
combination with LA dilatation in patients
with normal EFs is associated with a poor
prognosis similar to a restrictive pattern in
dilated cardiomyopathy
The U-shaped relationship with LV diastolic
function makes it difficult to differentiate normal
from pseudonormal filling, particularly with
normal LVEF, without additional variables.
If mitral flow velocity at the start of atrial
contraction is
>
20 cm/s, E/A ratio will be
reduced due to fusion. Age dependent
Mitral E-velocity
DT
DT is influenced by LV relaxation, LV diastolic
pressures following mitral valve opening, and
LV stiffness
Feasible and reproducible.
A short DT in patients with reduced LVEF
indicates increased LVEDP with high accuracy
both in sinus rhythm and in AF
DT does not relate to LVEDP in normal LVEF.
Should not be measured with E and A fusion
due to potential inaccuracy.
Age dependent
Pulsed-wave
TDI-derived
mitral annular
early diastolic
velocity: e
′
A significant association is present between e
′
and the time constant of LV relaxation shown
in both animals and humans.
The haemodynamic determinants of e
′
velocity
include LV relaxation, restoring forces and
filling pressure
Feasible and reproducible.
LV filling pressures have a minimal effect on e
′
in the presence of impaired LV relaxation.
Less load dependent than conventional blood-
pool Doppler parameters
Need to sample at least two sites with precise
location and adequate size of sample volume.
Different cut-off values depending on the
sampling site for measurement.
Age dependent
Mitral E/e
′
ratio e
′
velocity can be used to correct for the effect
of LV relaxation on mitral E velocity, and E/e
′
ratio can be used to predict LV filling pressures
Feasible and reproducible.
Values for average E/e’ ratio
<
8 usually
indicate normal LV filling pressures, values
>
14 have high specificity for increased LV filling
pressures
E/e
′
ratio is not accurate in normal subjects,
patients with heavy annular calcification, mitral
valve and pericardial disease.
‘Gray zone’ of values in which LV filling
pressures are indeterminate.
Different cut-off values depending on the
sampling site for measurement
LV, left ventricular; LA, left atrial; LAP, left atrial pressure; LVEF, left ventricular ejection fraction; DT, mitral E-velocity deceleration time; e
′
, lateral early diastolic
velocity; AF, atrial fibrillation.