Impact of Respiratory Mechanics on Venous Return in Single Ventricle Physiology: A Clinical Imaging Study

In participants with single-ventricle physiology, it is unclear how respiratory mechanics affects venous return. The aim of this study was to evaluate the impact of respiratory effort and rate on venous return. We used magnetic resonance imaging to quantify flow in the inferior vena cava (IVC) in 20 participants with total cavopulmonary connection during a breathing study (shallow, baseline, deep, and slow, baseline, fast). Retrograde IVC flow rate, forward IVC flow rate, retrograde flow ratio, forward IVC flow volume, retrograde IVC flow volume, and pulsatility index were extracted. Increases in respiratory effort or rate increased retrograde flow and pulsatility.