Abstract
Accurate assessment of right ventricular (RV) function is drawing a
growing attention. Pressure-volume (PV) loop analysis is the gold
standard method for evaluating RV function; however, it is not widely
employed due to its invasive nature and complexity. The present report
is the first to have drawn a RV PV loop in a patient with pulmonary
hypertension, with a simultaneous recording of RV pressure and volume
using high fidelity micromanometry and 3D echocardiography. This allows
for less invasive and simple assessment of RV function, potentially
promoting better understanding and management of pulmonary hypertension
and other cardiovascular diseases.
Pressure-volume (PV) loop analysis is the gold standard for evaluating
left/right ventricular (RV) function. Its application has become
increasingly important in pulmonary arterial hypertension (PAH) because
RV function critically affects PAH patients’ outcome [1]. However,
PV loop analysis is not used widely because it is invasive and requires
dedicated catheters and expertise. Recent advances in three-dimensional
(3D) echocardiography have enabled non-invasive RV volume measurements,
potentially replacing conductance catheters required for RV volume
measurements.
The PV loop in Figure 1 was created using data obtained from
simultaneous 3D echocardiography for RV volume (Movie 1 ) and
high-fidelity micromanometry for RV pressure (Figure 2 ) in a
PAH patient. Using PV data along with the single-beat method,
end-systolic elastance (Ees) (1.22 mmHg/mL) and Ees/[arterial
elastance] (1.27), representative indices of RV systolic function and
RV-pulmonary arterial coupling, respectively, were calculated. The
representative index of RV relaxation, tau, was calculated as 36.3 ms.
The RV stiffness/compliance index, β, was 0.0412, calculated using Rain
et al.’s formula [2].
To the best of our knowledge, the PV loop image presented in this report
is the first to have been created with a simultaneously obtained RV
pressure and 3D echocardiography-derived volume. This method waives the
conductance catheter use, thereby significantly lessening examination
time, cost, and dedicated expertise needed. With better temporal
resolution of 3D echocardiography and by modifying the RV’s
pre/after-load, such as by Valsalva maneuver, a more detailed and less
invasive RV function assessment will become possible.
Acknowledgments: We thank Ms. Azusa Nakasato, Mamiko Inoue MT,
Mr. Hajime Hatanaka, and Dr. Hiroshi Ohira PhD for their assistance in
data collection and analysis.