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The Effect of Rheologic Factors on the Accuracy of Systolic Pulmonary Artery Pressure Estimation Using Bernoulli Equation

Demir Baykal

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Conference: 2012 International PHA Conference and Scientific Sessions

Release Date: 06.22.2012

Presentation Type: Abstracts

Demir Baykal, MD, FACC, FASE

Gwinnett Consultants in Cardiology, Medical Software LLC Duluth GA

BACKGROUND: We have observed that echocardiographic methods may overestimate systolic PA pressure measurement at lower pressure ranges , likely due to limitations of Bernoulli equation. We hypothesized that factors intrinsic to red blood cells , red blood cell mass or active generalized inflammation may affect maximum red blood cell velocity for a given pressure gradient.

METHODS: We compared red blood cell indices of 24 study patients (12 with connective tissue disease) with falsely elevated SPAP determined by echocardiogram as 36mmHg or more( mean SPAP=43mmhg) later reversed by right heart catheterization (mean SPAP=28mmhg) with 24 control patients with normal SPAP < 36mmHg on echocardiogram (mean SPAP =27mmhg).

RESULTS: Mean red blood cell mass (hematocrit) of the study group was 31 as opposed to 36 for control (p=0.01, ANOVA).CRP was also significantly higher for study group, mean =6 vs 2.1 for control group (p<0.001, ANOVA)

CONCLUSION: Low hematocrit or active generalized inflammation ,as reflected by high CRP, may influence the red blood cell velocity and may invalidate peak systolic PA pressure measurement with Bernoulli equation. This may explain high incidence of elevated systolic PA pressures determined by echocardiography in inpatients during acute illness.

The Effect of Rheologic Factors on the Accuracy of Systolic Pulmonary Artery Pressure Estimation Usi