To the Editor:

I read with interest the article by Johansson et al. highlighting pitfalls in diagnosing patient foramen ovale (PFO) by transesophageal echocardiography (TEE) and the use of saline contrast injection, in a retrospective study done on patients with obstructive sleep apnea. I congratulate the authors for enhancing our understanding of the echocardiographic detection of PFOs, which is clinically relevant given the association of PFOs with stroke, transient ischemic attack, and other clinical scenarios, and the ability to close PFOs percutaneously. I concur with their observations of reasons for the high false-negative rate for PFO detection on TEE during saline contrast injection through personal observations. The authors used a mean of 17.6 contrast injections per patient per protocol. Their Table 2 shows that between 2 and 15 injections per patient were needed just to have met the two prerequisites of septal bulge and concurrent filling of the right atrium adjacent to PFO location for PFO diagnosis. This number of injections appears excessive with respect to nursing time, volume load, risk for infection, and the potential need for longer patient sedation, not to mention the risk to the patient from potential air embolization in inexpert hands.

We have recently presented our experience with improving PFO diagnosis during TEE by using a blood-saline-air mixture that results in a denser right atrial opacification compared with a saline-air injection alone. I have also found induction of cough either voluntarily by the patient or by using a soft suction catheter to stimulate the pharynx in sedated patients unable to perform a Valsalva maneuver helpful to increase right atrial pressure and in producing septal bulge. The use of a “sigh” and its release in an intubated patient can be helpful in those unable to cough or perform the Valsalva maneuver. I have also found that elevating the injected arm and massaging it immediately after contrast injection is a helpful maneuver to improve right atrial opacification, particularly in patients with poor cardiac output. In our clinical practice, we have not needed to use more than five contrast injections in difficult-to-diagnose patients using these maneuvers.

The myth surrounding PFO diagnosis by echocardiography of appearance of saline contrast to the left heart within five beats of right heart opacification has been proven incorrect by earlier case reports and now by a systematic study by Johansson et al. , and the American Society of Echocardiography should consider writing its recommendations on the methodology of PFO diagnosis by transthoracic echocardiography and TEE.