CARDIOVASCULAR JOURNAL OF AFRICA • Vol 21, No 5, September/October 2010
AFRICA
255
The mechanisms of ventricular interaction are unknown butmay
relate to restriction of ventricular filling by the pericardium,
23
although most work has assessed only the effect of RV volume
expansion on LV function,
24
rather than vice versa. This suggests
that hypertension and left ventricular hypertrophy influence both
ventricles. Right ventricular hypertrophy has been demonstrated
among subjects with systemic hypertension.
17-19
This study also demonstrated significant differences in
the pulse wave velocities between hypertensive and normo-
tensive subjects, which suggest that right ventricular diastolic
dysfunction occurs in association with left ventricular diastolic
dysfunction among these subjects. Several studies have shown
that left ventricular diastolic dysfunction occurs early in hyper-
tension.
17,19,24,25
Left ventricular diastolic dysfunction is associ-
ated with the reduction of the early E wave and the subsequent
increase in the amplitude of the atrial A wave. This may then
be followed by several changes. Diastolic dysfunction has been
divided into four groups depending on various parameters (E/A
ratio, isovolumic relaxation time and deceleration time): early
stages, pseudonormalisation, late and restrictive pattern of
diastolic dysfunction.
26
Doppler studies of cardiac flow and tissue movement remain
the gold standard for estimating diastolic dysfunction with
echocardiography.
26,27
Doppler mitral flow pattern is very useful
in estimating diastolic dysfunction and by itself is usually
adequate to identify grade I (abnormal relaxation) and grade III
(restrictive filling) diastolic dysfunction. The remaining subjects
can be categorised as normal diastolic function or as having
pseudonormalisation (grade II diastolic dysfunction) by addi-
tional testing such as the Valsalva manoeuvre, pulmonary venous
flow pattern or tissue Doppler studies.
The abnormal relaxation that is frequently associated with
ageing has been suggested to be due to the associated myocar-
dial abnormalities and increased presence of cardiovascular risk
factors and may therefore probably not constitute physiological
aging.
28
Although the right ventricle is a lower pressure system
and echocardiographic assessment may be more difficult than
the left ventricle due to its shape and morphology, interventricu-
lar dependence suggests that similar changes may occur in the
right ventricle to those in the left ventricle due to the trophic
effect of systemic hypertension and volume changes in the left
ventricle.
This study demonstrated a similar pattern of tricuspid wave
velocities in diastole and mitral wave velocities with good statis-
tical correlations (
r
=
0.405,
p
<
0.001, Fig. 1). Also, the peak
aortic and peak pulmonary systolic velocities showed similar
statistical correlations (
r
=
0.555,
p
<
0.05, Fig 2). This suggests
furthermore that right ventricular function is affected by hyper-
tension in a similar pattern to left ventricular function. These
changes may be subtle in the early stages of the disease and may
require the use of more specific diagnostic parameters such as
tissue Doppler imaging and strain echocardiography.
27,29
However, this study failed to show a statistically significant
difference in the mean pulmonary systolic and peak pulmonary
systolic velocities between hypertensive subjects and controls.
We suggest that the changes in the pressures of the right ventri-
cle, although it is a low-pressure system, is influenced by the
pressure and volume changes associated with hypertension.
There is however no evidence that the right ventricular changes
occur at the same time as those of the left ventricle. Prospective
studies could document the timing of the right ventricular chang-
es associated with hypertension.
Conclusion
Hypertension affects the diastolic function of the left ventricle
and these changes are accompanied by similar changes in the
right ventricle. Whether these right heart changes occur early, at
the same time as left heart changes due to the interdependence
of the two structures, or whether it is a secondary phenomenon
possibly related to pulmonary vascular changes remains to be
proven by further studies. These changes occur in both the left
and right ventricles. The changes are also prominent in the
diastolic wave velocities, right ventricular wall dimensions and
internal chamber dimensions.
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