Glossopharyngeal insufflation (GI), a technique used by breath-hold divers to increase lung volume and augment diving depth and duration, is associated with untoward hemodynamic consequences. We performed transthoracic echocardiography in 5 elite breath-hold divers. During GI, heart rate increased in all (mean of 53 bpm to a mean of 100 bpm), and blood pressure fell dramatically (mean systolic, 112 mmHg to 52 mmHg; mean diastolic, 75 mmHg to non-detectable). GI induced a 46% decrease in mean left ventricular end-diastolic area, 70% decrease in left ventricular end-diastolic volume, 49 % increase in mean right ventricular end-diastolic area, and 160% increase in mean right ventricular end-diastolic volume. GI also induced biventricular systolic dysfunction; left ventricular ejection fraction decreased from 0.60 to a mean of 0.30 (p=0.012); right ventricular ejection fraction, from 0.75 to a mean of 0.39 (p<0.001). Wall motion of both ventricles became significantly abnormal during GI; left ventricular abnormalities involved hypokinesis or dyskinesis of the interventricular septum, while right ventricular wall motion abnormalities involved all visible segments. In two divers, the inferior vena cava dilated with the appearance of spontaneous contrast during GI, signaling increased right atrial pressure and central venous stasis. Conclusions: Hypotension during GI is associated with acute biventricular systolic dysfunction. The echocardiographic pattern of right ventricular systolic dysfunction is consistent with acute pressure overload, while concurrent left ventricular systolic dysfunction is likely due to ventricular interdependence.