Giant Hiatus Hernia Causing Pulmonary Vein Obstruction: Insights From <scp>4D</scp> Flow Cardiac <scp>MRI</scp>

Severe extrinsic compression of the left atrium by a giant hiatus hernia can obstruct left atrial inflow. 4D flow cardiovascular magnetic resonance is a novel, non-invasive imaging technique that can precisely quantify individual pulmonary vein flow dynamics, facilitating the diagnosis of functional venous obstruction in this rare clinical scenario.