Comparison of color flow imaging and peripheral venous saline contrast during transesophageal echocardiography to evaluate right-to-left shunt at the atrial level

Optimization of patent foramen ovale detection by contrast transthoracic echocardiography using second harmonic imaging

BACKGROUND

Patent foramen ovale is an anomaly responsible for paradoxical embolizations and cerebral ischemic events. Aims. - We want to show second harmonic transthoracic echography sensitized by contrast agent perfusion is as well as transesophageal echography to patent foramen ovale detection.

METHODS

Onene hundred twenty one patients referred for transesophageal echocardiography for patent foramen ovale detection, underwent additive second harmonic transthoracic echocardiography with one of three randomized contrast agents: a mixture A of dextrose and air, mixture B of dextrose and air and blood, or mixture C of hydroxyethylamidon. The severity of atrial shunting was evaluated on recordings by semi-quantitative scoring. Intensity of contrast was also assessed by objective quantitative videodensitometry.

RESULTS

No difference was observed between the two techniques, nor between mixture A, B and C in terms of PFO detection during each exam. However, quantitative contrast analysis showed higher intensity with mixtures B and C with mixture A during transthoracic echography.

CONCLUSIONS

When performed with a contrast agent, second harmonic transthoracic echography and transoesophageal echography are comparable when it comes to patent foramen ovale detection. Although the composition of the contrast agent does not appear to affect the rate of this detection, contrast quality in the right atrium during transthoracic exam is better with mixtures B and C than with mixture A.

Intracardiac shunts

Unsuspected intracardiac shunts can be a cause of acute deterioration in critically ill patients. Shunts can be acquired or congenital conditions that become symptomatic only with changed physiologic conditions. Transesophageal echocardiography is an excellent tool for the diagnosis of intracardiac shunts.