Case 4—2005 Utility of Transesophageal Echocardiography in the Diagnosis of a Previously Undetected Atrial Septal Aneurysm With Shunt

EFECTS OF THE interatrial septum are among the most common congenital cardiac lesions found in adults. The foramen ovale, a fetal remnant, remains probe patent in more than one third of the general population, making it the most common congenital cardiac abnormality. Functional closure of the foramen ovale usually occurs soon after birth when the left atrial pressure rises and presses the valve of the fossa ovalis against the septum secundum. A patent foramen ovale (PFO) occurs when the foramen ovale does not anatomically seal. This relatively common entity is detectable in up to 34% of the population at postmortem examination. 1,2 The incidence has been shown to be even higher in patients with stroke. 3 Complications associated with a PFO include right-to-left shunting with refractory hypoxemia, paradoxic embolism, migraine headache, 4 transient global amnesia, 5 decompression illness with paradoxic gas embolism in divers and astronauts, 6 and orthostatic desaturation with platypnea-orthodeoxia syndrome.7 Atrial septal aneurysm (ASA) is frequently seen in association with a PFO,8 and its presence has been related to focal cerebral events including stroke and transient ischemic attacks. Because of this association, paradoxic embolism is believed to be a likely mechanism of embolism in many patients with ASA. Transesophageal echocardiography (TEE) is the modality of choice for the detection of PFO and ASA. Because of the increasingly routine use of TEE in the operating room during cardiac surgery, it can be expected that more cases of previously undiagnosed PFO and ASA will be detected. The question then becomes whether these findings should prompt further surgical intervention, particularly if the patient is asymptomatic. Unfortunately, at this time, there are no data to support the optimal approach to this clinical dilemma. The authors present a patient with a history of transient ischemic attacks (TIA) of unknown origin who was scheduled for elective off-pump coronary artery bypass (OPCAB) surgery. Preoperative diagnostic tests did not disclose the source of TIAs; however, intraoperative TEE revealed an ASA with PFO leading to alteration of the planned surgical procedure.