Atrial Septal Defect and Patent Foramen Ovale
The prevalence of a patent foramen ovale (PFO) reaches 25 to 30 % of the general population. In patients having suffered a cryptogenic stroke, the incidence reaches 45.9 %,64 which suggests that PFO may play a significant role in the pathogenesis of cryptogenic stroke.65 Atrial septal defects (ASD) are the most common congenital heart defect found in adult patients.
The indications for defect closure include right ventricular volume overload with a pulmonary-to-systemic flow ratio >2:1, paradoxical embolisation and platypnea-orthodeoxia syndrome. The transcatheter treatment of PFOs and ASDs was first performed in 1975.66 Subsequent studies demonstrated that percutaneous closure has a similar rate of success when compared to surgical closure but offered reduced rates of complications and duration of hospital stay.67–69
Contrast-enhanced MSCT using a saline-chaser can be used to detect and differentiate inter-atrial shunts.70,71 and can also be used to assess disease severity.72 Ostium secundum ASDs, which represent 70 % of cases, are the only type amenable to percutaneous closure. In this context, MSCT can be useful to establish the diagnosis of sinusvenosus type ASD with partial anomalous pulmonary venous return, a condition better treated surgically.73,74
MSCT is also comparable to but less invasive than trans-esophageal echocardiography in the assessment of ASD prior to percutaneous septal occluder implantation.75