CARDIOVASCULAR JOURNAL OF AFRICA • Vol 21, No 4, July/August 2010
AFRICA
217
Right ventricular diastolic dysfunction
Similar to left ventricular diastolic dysfunction, there have been
multiple aetiologies associated with impairment in mechani-
cal compliance as well as relaxation parameters that lead to
right ventricular diastolic dysfunction. Over the years, right
ventricular diastolic dysfunction has been observed in a vari-
ety of settings, including obesity, cystic fibrosis, chronic aortic
stenosis, arterial hypertension and Chagas disease.
33-36
Studies
investigating the functional parameters of the right ventricle
during diastole were slow to formulate due to the difficulty of
correctly measuring right ventricular volume prior to the advent
of Doppler echocardiography.
37
The algorithm used for assess-
ment and diagnosis of right ventricular diastolic dysfunction
with Doppler echocardiography utilises pulsed-wave Doppler of
the transtricuspid flow, hepatic venous flow and tissue Doppler
imaging of the tricuspid annulus or tricuspid annular velocity.
38
Normal hepatic venous flow is defined as a ratio of systolic to
diastolic velocities greater than one with the atrial wave reversal
less than half the maximum systolic wave velocity.
39
Mild right
ventricular diastolic dysfunction is defined by E/A
<
1 in trans-
tricuspid flow velocities, or 1
<
E/A
<
2 with S/D
>
1 in hepatic
vein flow and early component of the tricuspid annular tissue
Doppler velocity (Et) less than atrial component of the tricuspid
annular tissue Doppler velocity (At), or an atrial reversal wave
more than half of the systolic wave of the hepatic vein flow.
Moderate or severe right ventricular diastolic dysfunction can
be assumed to be present if a reduced or inverted systolic wave-
form, respectively, is present on the Doppler hepatic vein flow
signal. Studies on pulmonary hypertension patients have led to
the speculation that right ventricular diastolic dysfunction may
be an independent factor contributing to right heart failure and
death in patients with pulmonary hypertension.
40
Gan
et al
. showed that in patients with pulmonary hyper-
tension, the increase in right ventricular afterload resulted in
ventricular hypertrophy and right ventricular diastolic dysfunc-
tion.
41
The degree of diastolic dysfunction correlated with the
severity of pulmonary hypertension, which improved with medi-
cal therapy that reduced afterload.
Right ventricular diastolic dysfunction in the setting of heart
failure was first reported by Riggs in 1993.
42
The author reported
impaired right ventricular filling parameters in six children with
dilated cardiomyopathy. Yu
et al
. published the first study that
systematically assessed right ventricular diastolic dysfunction
in 1996; comparing 114 patients with symptomatic heart fail-
ure (EF
<
50%) with 31 patients with pulmonary hypertension
(pulmonary systolic artery pressure
>
40 mmHg) as well as 40
healthy subjects.
43
The authors described a significant number of
patients with systolic heart failure and/or pulmonary hyperten-
sion suffering from right ventricular diastolic dysfunction. Even
after exclusion of patients with pulmonary hypertension, a statis-
tically significant percentage of heart failure patients suffered
right ventricular diastolic dysfunction.
In their analysis of 105 patients with systolic heart failure, Yu
and Sanderson demonstrated right ventricular diastolic dysfunc-
tion to be present in 21% of patients as assessed by echocardi-
ography.
44
Although a low-powered study, the authors concluded
that right ventricular diastolic dysfunction was an independent
predictor for non-fatal hospital admissions for unstable angina or
heart failure, even though it was not observed to be a prognostic
factor for mortality, either alone or in combination with left
ventricular diastolic dysfunction.
Right and left ventricular interaction in diastolic
dysfunction
The French physician Bernheim was one of the first to report
the concept of ventricular interdependence in 1910, noting that
right ventricular performance can be compromised through
compression of the right ventricle by a dilated or hypertrophied
left ventricle.
45
In 1956, Dexter explained a possible mechanism
for diastolic interdependence.
46
The ‘reverse Bernheim effect’
hypothesised an increase in right ventricular volume second-
ary to an atrial septal defect, which can cause the septum to
be displaced toward the left ventricular cavity and inhibit left
ventricular filling mechanisms. A decade later in 1967, Taylor
et
al
. reported that the distension of one ventricle during diastole
can affect the compliance of the neighbouring ventricle.
47
The term diastolic ventricular interaction refers to the concept
that compliance of one ventricle is influenced through a shared
septum by the changes in volume, pressure, and/or compliance of
the other ventricle.
47
Although there are implications that diasto-
lic ventricular interaction plays a role in exercise intolerance in
patients with systolic heart failure, we currently do not have a
great understanding of the possible role it may have in patients
with diastolic heart failure. Ventricular interactions have been
reported indirectly in patients with pathology of one ventricle
and diastolic dysfunction of the neighbouring ventricle.
Right ventricular diastolic dysfunction has been observed in
pathological conditions that result in elevated left ventricular
pressure, such as systemic hypertension, aortic stenosis and
hypertrophic cardiomyopathy.
38,48,49
The reverse has also been
reported in patients with elevated right ventricular volume or
pressure with impaired left ventricular diastolic function.
50
Furthermore, it has been suggested that right ventricular diastolic
dysfunction observed in patients with heart failure but normal
pulmonary artery pressures may be caused indirectly by coexist-
ent left ventricular diastolic dysfunction secondary to ventricular
interdependence.
51
Although a realistic prospect, the possible role
that diastolic ventricular interaction may play in the potential
progression from diastolic dysfunction to clinical heart failure is
currently not well established.
Progression of diastolic heart failure
In 2001, Aurigemma
et al
. published the possible rate of progres-
sion from asymptomatic diastolic dysfunction to clinical heart
failure.
52
The study analysed 2 671 individuals without coronary
heart disease, congestive heart failure or atrial fibrillation.
At baseline, 15% of the patients had diastolic dysfunction,
determined by echocardiography, with 170 participants eventu-
ally developing heart failure after a five-year follow-up period
(6.4%), concluding that echocardiographic findings can be
suggestive of the development of heart failure.
Despite arguments regarding exercise limitations and left
ventricular diastolic dysfunction representing a possible early
marker of myocardial damage, the rate of progression from
diastolic dysfunction to diastolic heart failure remains uncertain.
Currently there are no large clinical trials assessing the possi-
ble progression from asymptomatic right ventricular diastolic
dysfunction to clinical right ventricular failure.
