Prognostic role of pulmonary impedance estimation to predict right ventricular dysfunction in pulmonary hypertension

• Published in: ESC Heart Failure Vol. 10; no. 3; pp. 1811 - 1821
• Main Authors: Hungerford, Sara Louise, Kearney, Katherine, Song, Ning, Bart, Nicole, Kotlyar, Eugene, Lau, Edmund, Jabbour, Andrew, Hayward, Christopher Simon, Muller, David William Marshall, Adji, Audrey
• Format: Journal Article
• Language: English
• Published: England John Wiley & Sons, Inc 01.06.2023; John Wiley and Sons Inc; Wiley
• Subjects: Cardiac magnetic resonance imaging; Data analysis; Electric Impedance; Female; Flow velocity; Heart; Hemodynamics; Humans; Hydraulics; Hypertension, Pulmonary - complications; Hypertension, Pulmonary - diagnosis; Male; Original; Prognosis; Prospective Studies; Pulmonary arterial impedance; Pulmonary arteries; Pulmonary hypertension; Right heart catheterization; Right ventricular–pulmonary arterial coupling; Software; Veins & arteries; Ventricular Dysfunction, Right - diagnosis; Ventricular Dysfunction, Right - etiology; Pulmonary arterial impedance; Right ventricular-pulmonary arterial coupling; Right heart catheterization; Cardiac magnetic resonance imaging
• ISSN: 2055-5822; 2055-5822
• DOI: 10.1002/ehf2.14180

Background The effect of pulmonary hypertension (PH) on right ventricular (RV) afterload is commonly defined by elevation of pulmonary artery (PA) pressure or pulmonary vascular resistance (PVR). In humans however, one‐third to half of the hydraulic power in the PA is contained in pulsatile components of flow. Pulmonary impedance (Zc) expresses opposition of the PA to pulsatile blood flow. We evaluate pulmonary Zc relationships according to PH classification using a cardiac magnetic resonance (CMR)/right heart catheterization (RHC) method. Methods Prospective study of 70 clinically indicated patients referred for same‐day CMR and RHC [60 ± 16 years; 77% females, 16 mPAP <25 mmHg (PVR <240 dynes.s.cm−5/mPCWP <15 mmHg), 24 pre‐capillary (PrecPH), 15 isolated post‐capillary (IpcPH), 15 combined pre‐capillary/post‐capillary (CpcPH)]. CMR provided assessment of PA flow, and RHC, central PA pressure. Pulmonary Zc was expressed as the relationship of PA pressure to flow in the frequency domain (dynes.s.cm−5). Results Baseline demographic characteristics were well matched. There was a significant difference in mPAP (P < 0.001), PVR (P = 0.001), and pulmonary Zc between mPAP<25 mmHg patients and those with PH (mPAP <25 mmHg: 47 ± 19 dynes.s.cm−5; PrecPH 86 ± 20 dynes.s.cm−5; IpcPH 66 ± 30 dynes.s.cm−5; CpcPH 86 ± 39 dynes.s.cm−5; P = 0.05). For all patients with PH, elevated mPAP was found to be associated with raised PVR (P < 0.001) but not with pulmonary Zc (P = 0.87), except for those with PrecPH (P < 0.001). Elevated pulmonary Zc was associated with reduced RVSWI, RVEF, and CO (all P < 0.05), whereas PVR and mPAP were not. Conclusions Raised pulmonary Zc was independent of elevated mPAP in patients with PH and more strongly predictive of maladaptive RV remodelling than PVR and mPAP. Use of this straightforward method to determine pulmonary Zc may help to better characterize pulsatile components of RV afterload in patients with PH than mPAP or PVR alone.