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The American College of Chest Physicians (ACCP)
Clinical Practice Guidelines emphasize the use of echocardiography
in pulmonary arterial hypertension (PAH) with much of
the discussion involving the estimate of right ventricular
systolic pressure. There is a bit less focus on the use
of echo to evaluate right ventricular size and function
and how to best evaluate these parameters. Though there
may not be large, prospective trials for an evidence base,
can you give us your thoughts on how you think we should
assess the right ventricle? Dr Hinderliter, do you believe
that these recommendations or future research should focus
more on how to characterize right ventricular function
so it can be more consistently implemented in clinical
practice?
Alan L. Hinderliter, MD
Associate Professor of Medicine
Division of Cardiology
University of North Carolina School of Medicine
Chapel Hill, North Carolina |
As indicated in the ACCP consensus guidelines, Doppler
echocardiography is the “test of choice” for
noninvasive measurement of pulmonary arterial pressure
in patients in whom PAH is clinically suspected. In studies
performed by experienced sonographers, pulmonary arterial
systolic pressure can be accurately estimated from the
velocity of the tricuspid regurgitant jet in most (though
not all) patients.
Similarly, a comprehensive echocardiogram is invaluable
in assessing cardiac causes of PAH, such as left ventricular
systolic or diastolic dysfunction, valvular heart disease,
or intracardiac shunts. Echocardiography is strongly recommended
for these indications.
Less widely recognized—and probably underemphasized
in the clinical practice guidelines—is the value
of echocardiography in assessing end-organ manifestations
of severe PAH. Right ventricular failure is the most common
cause of death in patients with PAH, and the results of
several observational studies suggest that echocardiographic
evaluation of right ventricular structure and function
can provide important prognostic information.1-3 Investigators
at the Mayo Clinic have developed a Doppler-derived index
of right ventricular myocardial performance that represents
the sum of isovolumetric contraction and relaxation times
divided by
the ejection time. When retrospectively measured in 53
patients with idiopathic PAH, this index of global right
ventricular function was a potent and independent predictor
of cardiac death and lung transplantation.1
Abnormalities in the Doppler flow velocity patterns of
right ventricular ejection (due to increased right ventricular
impedance) and left ventricular filling (due to abnormal
ventricular interaction) are common findings in patients
with severe PAH. In a cohort of 26 patients with PAH described
by Eysmann et al2 a short
right ventricular acceleration time (<62 ms) and a
ratio of early to late transmitral flow velocities (E/A)
<1 were associated with reduced survival. Raymond et
al3 reported that two structural
manifestations of right ventricular decompensation—
right atrial enlargement and displacement of the ventricular
septum—were indicative of a poor prognosis in 81
patients with idiopathic PAH and Class III or Class IV
symptoms. A planimetered right atrial area in the apical
four-chamber view exceeding 20 cm2/m and a value >2
for the end-diastolic eccentricity index—a simple
measure of septal displacement measured from the parasternal
short axis view—were associated with a 2-year mortality
of between 40% and 50%. The presence of a pericardial
effusion, a common finding in patients with severe PAH
that reflects an elevated right atrial pressure, was a
powerful and independent predictor of mortality in the
studies by both Eysmann et al and Raymond et al.
Several important limitations of these studies should
be acknowledged. They were relatively small; they evaluated
patients with idiopathic PAH, and their relevance to patients
with PAH associated with portal hypertension, collagen
vascular disease, or other systemic disease is unclear;
they were conducted in an era when our therapeutic armamentarium
for treating PAH was limited; and they did not evaluate
a number of novel measures of right ventricular function
(eg, tricuspid annular velocity by tissue Doppler4)
and cardiac remodeling (eg, the relative sizes of the
right and left ventricles5)
of potential value. Nonetheless, the very consistent theme
that has emerged is that echocardiographic evidence of
right ventricular failure is an ominous finding. Additional
research to further define the role of echocardiography
in assessing prognosis and guiding therapy in patients
with PAH would be of value.
In patients with severe idiopathic PAH, however, there
is ample evidence to support a comprehensive echocardiographic
examination to assess the extent of target organ disease
as an important component of the routine evaluation. The
assessment by an experienced echocardiographer of the
degree of right ventricular enlargement and dysfunction,
utilizing simple measures—the presence of a pericardial
effusion, an E/A ratio <1, a right ventricular acceleration
time <62 ms, a planimetered right atrial size >20
cm2/m, and a diastolic eccentricity index <2—or
more complex parameters, such as the Doppler right ventricular
index, can complement the clinical evaluation in assessing
prognosis and guiding therapy.
References
1.Yeo TC, Dujardin KS, Tei
C, Mahoney DW, McGoon MD, Seward JB. Value of a Doppler-derived
index combining systolic and diastolic time intervals
in predicting outcome in primary pulmonary hypertension.
Am J Cardiol. 1998;81:1157-61.
2.Eysmann SB, Palevsky HI,
Reichek N, Hackney K, Douglas PS. Twodimensional and Doppler-echocardiographic
and cardiac catheterization correlates of survival in
primary pulmonary hypertension. Circulation. 1989;80:353-60.
3.Raymond RJ, Hinderliter AL,
Willis PW, et al. Echocardiographic predictors of adverse
outcomes in primary pulmonary hypertension. J Am Coll
Cardiol. 2002;39:1214-9.
4. Meluzin J, Spinarova L,
Bakala J, et al. Pulsed Doppler tissue imaging of the
velocity of tricuspid annular systolic motion; a new,
rapid, and non-invasive method of evaluating right ventricular
systolic function. Eur Heart J. 2001;22:340-8.
5.Galie N, Hinderliter AL,
Torbicki A, et al. Effects of the oral endothelin-receptor
antagonist bosentan on echocardiographic and Doppler measures
in patients with pulmonary arterial hypertension. J Am
Coll Cardiol. 2003;41:1380-6.
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