What is the clinical evidence from this study?

Study design: Other. Population: Acute Pulmonary Embolism / Pulmonary Hypertension (n=8). Intervention: Echo-Doppler estimation of pulmonary arterial wave reflection vs. Invasive dual sensor-tipped catheter measurements. Primary outcome: Agreement of backward pressure (Pb) between echo-Doppler and catheter (Mean difference 0.4 mmHg, 95% CI -4.3 to 5.0).

What does this research mean for the field?

Doppler echocardiography can accurately estimate pulmonary arterial wave reflection indices, providing a non-invasive alternative to catheter-based measurements. Novelty: ClaimNovelty.METHODOLOGICAL. Consensus alignment: ConsensusAlignment.NEUTRAL.

December 8, 2021Open Access

Estimation of Pulmonary Arterial Wave Reflection by Echo-Doppler: A Preliminary Study in Dogs With Experimentally-Induced Acute Pulmonary Embolism

Key Result

Noninvasive echo-Doppler estimation of pulmonary arterial wave reflection agreed well with invasive catheter measurements, showing a mean difference in backward pressure of 0.4 mmHg.

Structured PICO

Does Doppler echocardiography accurately estimate pulmonary arterial wave reflection compared to invasive catheter measurements in a canine model of acute pulmonary embolism?

Population

8 healthy Beagle dogs (all females, aged 4-5 years old, weighted 10-13 kg) in a canine model of pulmonary hypertension induced by acute pulmonary micro-embolization.

Intervention

Non-invasive estimation of pulmonary arterial wave reflection (forward and backward pressures, reflection coefficient, wave speed) using Doppler echocardiography (tricuspid regurgitation and right ventricular outflow tract flow).

Comparator

Direct invasive measurement using a dual sensor-tipped pressure and flow wire (Combowire) catheter.

Outcome

Agreement between echo-Doppler derived wave reflection indices (backward pressure, reflection coefficient) and corresponding indices measured by invasive catheter.surrogate

Doppler echocardiography provides a reasonable, non-invasive estimation of pulmonary arterial wave reflection, offering a potential tool for integrative assessment of right ventricular afterload in pulmonary hypertension.

Main Result

Effect estimate: Mean difference 0.4 mmHg (95% CI -4.3 to 5.0)

Limitations

Small sample size (n=8) limits complete validation of the technique.
The animal model of acute pulmonary micro-embolization may not reflect all clinical scenarios or chronic adaptations.
Limits of agreement from Bland-Altman analysis are likely underestimated due to non-independence of data from the same animals.
Tricuspid regurgitation was artificially induced by the catheter, which may not always be present or measurable in clinical settings.

Abstract

Background: Pulmonary arterial (PA) wave reflection provides additional information for assessing right ventricular afterload, but its applications is hampered by the need for invasive pressure and flow measurements. We tested the hypothesis that PA pressure and flow waveforms estimated by Doppler echocardiography could be used to quantify PA wave reflection. Methods: Doppler echocardiographic images of tricuspid regurgitation and right ventricular outflow tract flow used to estimate PA pressure and flow waveforms were acquired simultaneously with direct measurements with a dual sensor-tipped catheter under various hemodynamic conditions in a canine model of pulmonary hypertension ( n = 8). Wave separation analysis was performed on echo-Doppler derived as well as catheter derived waveforms to separate PA pressure into forward (Pf) and backward (Pb) pressures and derive wave reflection coefficient (RC) defined as the ratio of peak Pb to peak Pf. Results: Wave reflection indices by echo-Doppler agreed well with corresponding indices by catheter (Pb: mean difference = 0.4 mmHg, 95% limits of agreement = −4.3 to 5.0 mmHg; RC: bias = 0.13, 95% limits of agreement = −0.25 to 0.26). RC correlated negatively with PA compliance. Conclusion: This echo-Doppler method yields reasonable measurement of reflected wave in the pulmonary circulation, paving the way to a more integrative assessment of pulmonary hemodynamics in the clinical setting.

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