Relationship between quantitative and descriptive methods of studying blood flow through intrapulmonary arteriovenous anastomoses during exercise.

Several methods exist to study intrapulmonary arteriovenous anastomoses (IPAVA) in humans. Transthoracic saline contrast echocardiography (TTSCE), i.e., bubble scores, is minimally-invasive, but cannot be used to quantify the magnitude of blood flow through IPAVA (QIPAVA ). Radiolabeled macroaggregates of albumin (99m Tc-MAA) have been used to quantify QIPAVA in humans, but this requires injection of radioactive particles. Previous work has shown agreement between 99m Tc-MAA and TTSCE, but this has not been tested simultaneously in the same group of subjects. Thus, the purpose of this study was to determine if there was a relationship between QIPAVA quantified with 99m Tc-MAA and bubble scores obtained with TTSCE. To test this, we used 99m Tc-MAA and TTSCE to quantify and detect QIPAVA at rest and during exercise in humans. QIPAVA significantly increased from rest to exercise using 99m Tc-MAA and TTSCE and there was a moderately-strong, but significant relationship between methods. Our data suggest that high bubble scores generally correspond with large QIPAVA quantified with 99m Tc-MAA during exercise.