Key result
In a rabbit model, the extent of reflected waves was 15.7% in controls, decreased to 3.6% with chronic embolization, and increased to 37.3% with acute embolization.
Why the study?
Locating the site of increased vascular resistance in pulmonary arterial hypertension could assist diagnosis and treatment, and wave intensity analysis may localize major reflection sites.
Does the pattern of wave reflection in the pulmonary circulation change in response to different forms of vascular occlusion in a rabbit model?
Does the pattern of wave reflection in the pulmonary circulation change in response to different forms of vascular occlusion in a rabbit model?
Absolute Event Rate: 3.6% vs 15.7%
The pulmonary vascular tree generates an open-end reflection pattern that may assist ejection, but chronic obstruction significantly modifies this pattern, suggesting wave intensity analysis could help localize increased resistance in pulmonary hypertension.
Animal model data on pulmonary wave reflections are hypothesis-generating; leaves open whether wave intensity analysis can localize resistance in clinical pulmonary hypertension.
Locating the site of increased resistance within the vascular tree in pulmonary arterial hypertension could assist in both patient diagnosis and tailoring treatment. Wave intensity analysis (WIA) is a wave analysis method that may be capable of localizing the major site of reflection within a vascular system. We investigated the contribution of WIA to the analysis of the pulmonary circulation in a rabbit model with animals subjected to variable occlusive pulmonary disease. Animals were embolized with different sized microspheres for 6 wk ( n = 10) or underwent pulmonary artery (PA) ligation for 6 wk ( n = 3). These animals were compared with a control group ( n = 6) and acutely embolized animals ( n = 4). WIA was performed and compared with impedance-based methods to analyze wave reflections. The control group showed a relatively high extent of reflected waves (15.7 ± 10.6%); reflections had a net effect of pressure reduction during systole, suggesting an open-end reflector. The pattern of wave reflection was not different in the group with partial PA ligation (12.4 ± 4.1%). In the chronically embolized group, wave reflection was not observed (3.6 ± 1.5%). In the acute embolization group, wave reflection was more prominent (37.3 ± 12.6%), with the appearance of a novel wave increasing pressure, suggesting the appearance of a closed-end reflector. Wave reflections of an open-end type are present in the normal rabbit pulmonary circulation. However, the pattern and nature of reflections vary according to the extent of pulmonary vascular occlusion. NEW & NOTEWORTHY The study proposes an original framework of a complementary analysis of wave reflections in the time domain and in the frequency domain. The methodology was used in the pulmonary circulation with different forms of chronic obstructions. The results suggest that the pulmonary vascular tree generates a reflection pattern that could actually assist the heart during ejection, and chronic obstruction significantly modifies the pattern.
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Eynden et al. (2019) studied Occlusive pulmonary disease (n=23). Variable occlusive pulmonary disease (chronic embolization, acute embolization, partial PA ligation) vs. Control group was evaluated on Extent of reflected waves. In a rabbit model, the extent of reflected waves was 15.7% in controls, decreased to 3.6% with chronic embolization, and increased to 37.3% with acute embolization.
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