Wave intensity analysis in the pulmonary circulation and pulmonary haemodynamics in advanced heart failure

Yim, Ivan Hoi Wing ORCID: 0000-0003-3398-4600 (2025). Wave intensity analysis in the pulmonary circulation and pulmonary haemodynamics in advanced heart failure. University of Birmingham. Ph.D.

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Abstract

Wave intensity analysis (WIA) uses simultaneous changes in pressure and flow velocity to determine wave energy, type and timing of traveling waves in the circulation. It has the unique advantage over other impedance-based methods in that it analyses the pressure and velocity waveforms as successive wavefronts and not sinusoidal wavetrains. The analysis is performed in the time domain, allowing clinicians to intuitively relate the arterial waves to events in the cardiac cycle. In this thesis, I investigated WIA in patients with heart failure and durable LVAD therapy. I found that wave propagation in the pulmonary circulation in the context of heart failure was comparable with the systemic circulation; wave reflection was more likely at higher pulmonary arterial pressures and with lower pulmonary arterial compliance. There were no significant changes in wave propagation nor reflection associated with LVAD pump speed changes at +/- 300 rpm. I also investigated haemodynamic parameters associated with MCS usage following orthotopic heart transplantation and found that a lower pulmonary arterial pulsatility index (PAPI) is independently associated with MCS use for severe early graft dysfunction following heart transplantation. Using the same haemodynamic data, I also explored a stroke volume calculator derived from pulmonary haemodynamics. I found that after calibration, it was possible to track changes in stroke volume based on pulmonary pulse pressure, however, this calculator requires further validation using data from different patient cohorts. At the inception of the project, there was ambition to develop WIA into a clinical tool, however with the current technology, I conclude that this is not yet possible due to the difficulty in acquiring a clean velocity signal and the need for more data.

Type of Work:

Thesis (Doctorates > Ph.D.)

Award Type:

Doctorates > Ph.D.

Supervisor(s):