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.