Heart, Lung and Circulation

Novel Use of Intra-arterial Doppler in the Assessment of Pulmonary Artery Flow Velocities—Observations Before and After Therapy for Pulmonary Arterial Hypertension

      Background: Intra-arterial Doppler is a novel technique which enables accurate assessment of blood flow haemodynamics. We evaluated the feasibility of using intra-arterial Doppler for insights into the pulmonary artery flow velocity profile in patients with pulmonary arterial hypertension (PAH), and determined the changes in the flow velocity profile following pulmonary vasodilator therapy.
      Methods: Intra-arterial Doppler was performed in the pulmonary arteries of seven subjects with PAH before and after six months of Bosentan therapy. The following Doppler derived parameters were measured: acceleration time (AcT), systolic ejection time (ET), ratio of acceleration time to systolic ejection time (AcT/ET), systolic velocity time integral (sVTI), diastolic velocity time integral (dVTI) and total velocity time integral (tVTI). Relationships between Doppler parameters and clinical response to Bosentan therapy were analysed.
      Results: At baseline, all PAH patients displayed a Doppler flow velocity profile consisting of a sharp rise to peak velocity followed by mid-to-late systolic notching. In one patient, systolic notching disappeared following Bosentan therapy. Only clinical responders (n = 3) demonstrated a significant increase in tVTI (583 ± 132 versus 897 ± 138, p = 0.023), and an increase in dVTI (62 ± 28 versus 195 ± 40, p = 0.044). No significant change was observed in VTI amongst non-responders.
      Conclusion: Intra-arterial Doppler is feasible in the quantitative characterisation of pulmonary artery flow velocity profile. An increase in pulmonary blood flow, particularly diastolic flow, was associated with a clinical response to Bosentan therapy. This technique may provide additional insights into the haemodynamics of the pulmonary circulation in pathophysiological states.