Patent Foramen Ovale: A Practical and Imaging Based Morphological Classification

Abstract

Objectives: Patent foramen ovale (PFO) has been implicated in cryptogenic stroke, transient ischemic attacks, migraine with auras, decompression sickness and severe refractory hypoxemia. Recently published data provided sufficient evidence for the percutaneous closure of PFO in the embolic stroke of an undetermined source. After a suspicion for a paradoxical cerebral embolism, a transthoracic echocardiography, transcranial doppler study, and transesophageal echocardiography using contrast bubble injection are indicated. Detection of PFO is possible during contrast bubble injection with or without Valsalva maneuver in transesophageal echocardiography. Three- or two-dimensional transesophageal echocardiography (TEE) give opportunity to obtain detailed information about complex anatomical variations in PFO morphologies including atrial septal aneurysm, large tunnel, increased height of PFO, lipomatous hypertrophy. Ideal device selection is important for the appropriate closure of PFO. A standardized classification is needed to define PFO morphologies when selecting the device size. In our study, we aimed to create a common language for different and high-risk morphologies with two-dimensional (2D) and three-dimensional (3D) TEE in patients with cryptogenic stroke that would be helpful in transcatheter PFO closure. Materials and Methods: One hundred eleven one patients with the diagnosis of cryptogenic stroke and with high “The Risk of Paradoxical Embolism” (RoPE) score (>7) were included in the study. From the recorded images, interatrial septum was evaluated retrospectively with 2D and 3D TEE. Also, transcranial doppler, contrast bubble injection in TEE, 12-lead electrocardiography was performed. The amount of shunting during bubble study was recorded. According to analysis with 2D and 3D TEE technique, we classified the subtypes of different PFO morphologies into two main types and subgroups according to atrial septal aneurysm. Results: 2D and 3D transesophageal echocardiography was applied to all patients before and during the PFO closure procedure. The amount of shunting was severe in 64 patients (57.7%) patients. PFO tunnel was found to be spontaneously open in 64 patients. Most of patients had long PFO tunnel and mean tunnel length was 11.47±2.26 mm. The mean atrial septal defect (ASD) size accompanying PFO was 3.17±1.64 mm (large ASD). There were atrial septal defects accompanying PFO in 28 (25.2 %) patients. The mean of opening length of PFO (height of PFO) which can induce severe shunting was 4.06±1.6 mm. Atrial septal aneurysm was existed in 22 (19.8 %) patients. The total amount of other then simple morphologies which carry high risk features were higher. We found that the most frequent device selected by the operator was multi-fenestrated septal occluder (cribriform). The multi-fenestrated septal occluder devices were implanted in 69.4% of patients. The more complex anatomy led the operator for to choose mostly multi-fenestrated devices. Conclusion: After defining PFO morphologies and categorizing the different types, we would be able to express the same morphological classification which could be easily and repetitively used. With the usage of a well-known classification, device type selection could be standardized for optimization of percutaneous transcatheter closure of PFO while minimizing the complications and increasing procedural success.