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External Doppler is an Accurate and Reproducible Method of Measuring Cardiac Output in Patients with Pulmonary Hypertension

Rael Sundy

J. Billadello

J. Zhen

T. Ahrens

Murali Chakinala


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Conference: 2008 International PHA Conference and Scientific Sessions

Release Date: 06.20.2008

Presentation Type: Abstracts

Sundy R., Billadello J., Zhen J., Ahrens T., Chakinala M.

Barnes Jewish Hospital and Washington University in St Louis, Division of Biostatistics, St. Louis, MO, USA

BACKGROUND: Measurement of cardiac output (CO) is a vital part of evaluating and managing patients with pulmonary arterial hypertension (PAH).  Non-invasive estimation of the CO by continuous Doppler wave isonation of the aortic and pulmonary outflow tracts has potential clinical value but has not been evaluated in patients with PAH.

METHODS: In this prospective & observational study, patients diagnosed with or suspected of having PAH and undergoing a diagnostic right heart catheterization (RHC) were recruited for simultaneous non-invasive CO measurement with an external continuous wave USCOM Doppler device (USCOM Ltd). While blinded to invasive RHC data, a single operator measured CO, peak velocity and flow time with the Doppler device at the supra-sternal notch (aortic) and pulmonary outflow tract locations. Intra-class correlation coefficients (ICC) were determined between invasive CO (by assumed Fick method) and the non-invasive CO. The impact of potential confounding variables on the non-invasive signal quality was explored.

RESULTS: 17 patients (mean age 45yrs; 83% female; 41% idiopathic and 23% collagen vascular disease) were enrolled and adequate images were obtained in 16. Invasive mean PAP=52mmHg, CO= 4.4L/min and mean RAP=9.7mmHg.  ICC was good (0.78, 95% CI 0.49-0.91) between the CO measurements obtained by invasive and non-invasive techniques. Invasive CO correlated better with pulmonary r=0.74 (p=0.001) than with aortic values r= 0.37. No significant determinants of image quality were uncovered.

CONCLUSION: Non-invasively derived Doppler estimation of cardiac output is accurate in patients with pulmonary arterial hypertension.  Further investigation of its potential application as a longitudinal monitoring tool is warranted.