Vascular impedance characterization in chronic pulmonary hypertension
Purpose: Lung transplantation is now an acceptable form of therapy for pulmonary hypertension (PH). Controversy still remains regarding the most appropriate surgical procedure (single lung vs. bilateral lung vs. heart-lung). However, to date, there has been no appropriate large animal model of stable PH to examine the effects of various surgical options on pulmonary hemodynamics in an experimental setting. In this study, alterations in the pulmonary vascular impedance occurring in the setting of chronic PH (CPH) were studied using an established canine model of monocrotaline pyrrole (MCTP)-induced CPH with 16 mongrel dogs (23-25 kg). Methods: Animals underwent percutaneous pulmonary artery (PA) catheterization to measure right heart pressures before and 8 weeks after an injection of either 3 mg/kg MCTP (n=8) or placebo (CTL, n=8). Eight weeks post-injection, hearts were instrumented with a PA flow probe, sonomicrometric dimension transducers and RV/LV micromanometers. Harmonic derivation of functional data was achieved with Fourier analysis. Lung biopsies were taken for water content analysis. Results: Lung water content was not significantly different between CTL and MCTP (79.65±0.35% vs. 80.13±0.33%). The changes in pulmonary hemodynamics are displayed (Qpa=pulmonary blood flow, LAP=left atrial pressure, PVR=pulmonary vascular resistance, TP=total power, SW=stroke work, Z0=characteristic impedance, EFF=transpulmonary efficiency). Results are expressed as mean and SEM (t-test, *=p<0.01, †=p<0.05 vs. CTL). CTL MCTP Qpa (ml/min) 1384 (87) 1236 (92) PAP (mm Hg) 11.45 (0.56) 20.57*(0.83) LAP (mm Hg) 3.71 (0.27) 5.72*(0.59) PVR (dyne*sec*cm-5) 461 (37) 951*(129) TP (mW) 49.64 (2.95) 67.83†(7.59) Z0 (dyne*sec*cm-5) 384 (95) 307 (55) EFF (ml/min/mW) 36.17 (2.28) 24.86*(2.47). Conclusions: Significant increases in PAP and PVR were observed 8 weeks post-MCTP injection. In the setting of CPH, pulmonary blood flow is maintained by an significant increase in total power, but with a significant decrease in EFF. Clinical Implications: This large animal model of stable CPH provides a potentially useful means by which to evaluate surgical options for improving pulmonary hemodynamics in the setting of CPH.
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- Respiratory System
- 3202 Clinical sciences
- 3201 Cardiovascular medicine and haematology
- 1103 Clinical Sciences
Citation
Published In
ISSN
Publication Date
Volume
Issue
Related Subject Headings
- Respiratory System
- 3202 Clinical sciences
- 3201 Cardiovascular medicine and haematology
- 1103 Clinical Sciences