Document Detail


Pulmonary vascular input impedance is a combined measure of pulmonary vascular resistance and stiffness and predicts clinical outcomes better than pulmonary vascular resistance alone in pediatric patients with pulmonary hypertension.
MedLine Citation:
PMID:  18082509     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
BACKGROUND: Pulmonary vascular resistance (PVR) is the current standard for evaluating reactivity in children with pulmonary arterial hypertension (PAH). However, PVR measures only the mean component of right ventricular afterload and neglects pulsatile effects. We recently developed and validated a method to measure pulmonary vascular input impedance, which revealed excellent correlation between the zero harmonic impedance value and PVR and suggested a correlation between higher-harmonic impedance values and pulmonary vascular stiffness. Here we show that input impedance can be measured routinely and easily in the catheterization laboratory, that impedance provides PVR and pulmonary vascular stiffness from a single measurement, and that impedance is a better predictor of disease outcomes compared with PVR.
METHODS: Pressure and velocity waveforms within the main pulmonary artery were measured during right heart catheterization of patients with normal pulmonary artery hemodynamics (n = 14) and those with PAH undergoing reactivity evaluation (49 subjects, 95 conditions). A correction factor needed to transform velocity into flow was obtained by calibrating against cardiac output. Input impedance was obtained off-line by dividing Fourier-transformed pressure and flow waveforms.
RESULTS: Exceptional correlation was found between the indexed zero harmonic of impedance and indexed PVR (y = 1.095x + 1.381, R2 = 0.9620). In addition, the modulus sum of the first 2 harmonics of impedance was found to best correlate with indexed pulse pressure over stroke volume (y = 13.39x - 0.8058, R2 = 0.7962). Among a subset of patients with PAH (n = 25), cumulative logistic regression between outcomes to total indexed impedance was better (R(L)2 = 0.4012) than between outcomes and indexed PVR (R(L)2 = 0.3131).
CONCLUSIONS: Input impedance can be consistently and easily obtained from pulse-wave Doppler and a single catheter pressure measurement, provides comprehensive characterization of the main components of RV afterload, and better predicts patient outcomes compared with PVR alone.
Authors:
Kendall S Hunter; Po-Feng Lee; Craig J Lanning; D Dunbar Ivy; K Scott Kirby; Lori R Claussen; K Chen Chan; Robin Shandas
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Publication Detail:
Type:  Journal Article; Research Support, N.I.H., Extramural     Date:  2007-09-27
Journal Detail:
Title:  American heart journal     Volume:  155     ISSN:  1097-6744     ISO Abbreviation:  Am. Heart J.     Publication Date:  2008 Jan 
Date Detail:
Created Date:  2007-12-17     Completed Date:  2008-01-10     Revised Date:  2014-09-18    
Medline Journal Info:
Nlm Unique ID:  0370465     Medline TA:  Am Heart J     Country:  United States    
Other Details:
Languages:  eng     Pagination:  166-74     Citation Subset:  AIM; IM    
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MeSH Terms
Descriptor/Qualifier:
Adolescent
Blood Pressure Determination
Case-Control Studies
Child
Child, Preschool
Electric Impedance
Female
Heart Defects, Congenital / diagnosis*
Hemodynamics / physiology
Humans
Hypertension, Pulmonary / diagnosis*
Linear Models
Logistic Models
Male
Predictive Value of Tests
Probability
Pulmonary Artery / pathology*
Pulmonary Circulation / physiology*
Reference Values
Sensitivity and Specificity
Severity of Illness Index
Signal Processing, Computer-Assisted
Vascular Resistance*
Grant Support
ID/Acronym/Agency:
HL081506/HL/NHLBI NIH HHS; K24-HL084923/HL/NHLBI NIH HHS; M01 RR000069/RR/NCRR NIH HHS; M01 RR000069-457038/RR/NCRR NIH HHS; M01-RR0069/RR/NCRR NIH HHS; P50 HL084923/HL/NHLBI NIH HHS; P50 HL084923-02/HL/NHLBI NIH HHS; R01 HL067393/HL/NHLBI NIH HHS; R01 HL067393-04/HL/NHLBI NIH HHS; R01-HL067393/HL/NHLBI NIH HHS; T32-HL072738/HL/NHLBI NIH HHS
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