RESUMO
We describe a patient who suffered a stroke of unknown origin and presented a patent foramen ovale (PFO) at contrast echocardiography. This PFO was clearly detectable after contrast delivery in the femoral vein, while repeated contrast delivery in an antecubital vein only showed a negative contrast effect, which suggests that the blood crossing the PFO originated from the vena cava inferior. However, enhanced detection of a PFO by femoral contrast delivery, compared to antecubital injection has been published many years ago, this mode is not widely implemented yet. With this case report we would like to illustrate that the negative contrast effect may be used as an indicator that a PFO cannot be excluded and a switch to femoral contrast injection is then mandatory.
