The left atrium is susceptible to compression from any abnormal adjacent structure, including a dilated stomach or esophagus. Possible mechanisms for the observed decreased cardiac output and pulmonary congestion include obstruction of left atrial inflow and direct impairment of ventricular filling, causing functional tamponade. Clinical manifestations of compression include tachycardia, tachypnea, hypotension, and hypoxia, as shown in our patients. The clinical presentation may mimic that seen with more common clinical catastrophes, such as pulmonary embolus, acute myocardial infarction, or acute respiratory failure. The transient loss of normal gastric motility as a result of abdominal surgery, as in two of our patients, may in part explain our unique findings.
Transthoracic echocardiography is the test of choice for diagnosing left atrial compression.
In contrast to intrinsic atrial abnormalities, such as thrombus or myxoma, extrinsic masses move asynchronously with the atria. Left atrial compression by the esophagus, the stomach, or both is an uncommon but important cause of hemodynamic compromise. Timely diagnosis and the prompt removal of gastric contents will usually lead to the return of normal hemodynamic function. David I. Silverman, MD, Cardiology L3108, University of Connecticut Health Center, Farmington, CT 06030. Echocardiographic manifestations of mediastinal masses compressing or encroaching on the heart.