A modified Valsalva maneuver increases the detection rate of patent foramen ovale in transcranial sonography

Aim: Patent foramen ovale (PFO) is discussed as a source of paradoxical embolism in cryptogenic stroke. In clinical routine, PFO can be diagnosed either by echocardiography or by transcranial ultrasound after application of an ultrasonic contrast agent. It is commonly recommended to start the Valsalva maneuver (VM) 10s after injection of the contrast agent in the right antecubital vein. The observation that in patients with known PFO microbubbles occur mainly a few seconds after the release of the VM and only sparsely during the maneuver itself, induced this study, in which we compared the rate of detected PFOs…