The relationship between pulmonary artery wedge pressure and pulmonary blood volume derived from contrast echocardiography: A proof-of-concept study

BACKGROUND: Pulmonary transit time (PTT) obtained from contrast-echocardiography is a marker of global cardiopulmonary function. Pulmonary blood volume (PBV), derived from PTT, may be a non-invasive surrogate for left-sided filling pressures, such as pulmonary artery wedge pressure (PAWP). We sought to assess the relationship between PBV obtained from contrast-echocardiography and PAWP. METHODS: Participants were adult survivors of childhood cancer that had contrast-echocardiography performed nearly simultaneously with right-heart catheterization. PTT was derived from time-intensity curves of contrast passage through the right-ventricle (RV) and left atrium (LA). PBV relative to overall stroke volume (rPBV) was estimated from the product of PTT and heart rate during RV-LA transit. PAWP was obtained during standard right-heart catheterization. The Spearman correlation coefficient was used to assess the relationship between rPBV and PAWP. RESULTS: The study population consisted of 7 individuals who had contrast-echocardiography and right-heart catheterization within 3 hours of each other. There was a wide range of right atrial (1–17 mmHg), mean pulmonary artery (18–42 mmHg), and PAW pressures (4–26 mmHg) as well as pulmonary vascular resistance (< 1 to 6 Wood Units). We observed a statistically significant correlation between rPBV and PAWP (r = 0.85; p = 0.02). CONCLUSION: Relative PBV derived from contrast-echocardiography correlates with PAWP. If validated in larger studies, rPBV could potentially be used as an alternative to invasively determined left-sided filling pressure.