Percutaneous Closure of Patent Foramen Ovale and Atrial Septal Defect

Percutaneous Closure of Patent Foramen Ovale and Atrial Septal Defect

Ricardo Cigarroa

Ignacio Inglessis



Patent foramen ovale (PFO) is the most common intracardiac shunt encountered in clinical practice. The foramen ovale is an essential component of the fetal circulation, allowing highly oxygenated placental blood to flow directly from the right to left atrium, bypassing the fetal lungs and directly supplying the coronary arteries and fetal brain. A communication between septum secundum and septum primum, the foramen ovale typically closes in most individuals in the first year of life following hemodynamic changes that increase left atrial (LA) pressure and decrease right atrial (RA) pressure. The LA pressure rise is the result of an increase in systemic vascular resistance after interruption of the umbilical cord and rising pulmonary venous return to the LA after lung expansion. In addition, RA pressure falls as a result of reducing blood return to the RA after ductus venosus closure and decreasing pulmonary vascular resistance after lung expansion. The competent valve of the foramen ovale is then pressed to the interatrial limbus, and functional closure of the foramen ovale, without left-to-right interatrial shunt, occurs as a result of LA pressure in excess of RA pressure.

The foramen ovale remains patent in about one-third of the population for unknown reasons, although there is evidence to suggest a genetic predisposition.1 The prevalence of PFO appears to decrease with age, whereas older age is associated with larger PFOs.2 The majority of individuals with a PFO will remain asymptomatic, but a small percentage develop clinically significant pathology from this communication and benefit from percutaneous closure.


Cryptogenic Stroke

PFOs are implicated in the pathophysiology of cryptogenic strokes by allowing clot formed in the venous system to cross into the arterial circulation.16,17 However, multiple early investigations failed to show definitive benefit of routine PFO closure for this indication.18,19,20 A diagnosis of cryptogenic stroke may be made when there is clinical and radiologic evidence
of an ischemic stroke and no cause is readily identifiable.21,22 Important etiologies to investigate prior to making the diagnosis of cryptogenic stroke include atrial fibrillation, peripheral artery disease, endocarditis, and hypercoagulable state. Cryptogenic strokes are more common in younger patients who lack risk factors for stroke that accrue with age.23,24

Recently, three large randomized control trials found a significant reduction in recurrent stroke in patients who underwent transcatheter PFO closure when compared with patients who were treated with antiplatelet therapy alone after experiencing cryptogenic stroke8,9,10 (Table 46.2). These trials enrolled patients who were unlikely to have a stroke from reasons other than paradoxical embolus by ruling out atrial fibrillation, hypercoagulable states, and carotid disease prior to closure. Furthermore, older patients and patients with uncontrolled risk factors for stroke were excluded from the studies. Important eligibility criteria included an age limit of 60 years, moderate or large PFO size, and the presence of an interatrial septal aneurysm, which has been associated with recurrent cryptogenic stroke.11

Decompression Sickness

Decompression sickness is a severe illness that affects individuals exposed to increased atmospheric pressures. It is most commonly encountered in scuba divers, although it also can occur during high-altitude or unpressurized air travel.25 This condition occurs when nitrogen dissolved in the blood and tissues by high pressure forms bubbles as pressure decreases. These bubbles may cross into the arterial system through a PFO and lead to stroke. Other symptoms include musculoskeletal pain, rash, confusion, paresthesias, paralysis, and respiratory distress. Severe decompression syndrome requires expedient treatment with hyperbaric chamber therapy. Although there are no large studies to recommend routine closure in divers, one small randomized study found that subjects who underwent PFO closure had less arterial bubbles when compared to those who did not in patients exposed to similar conditions.26 After PFO closure, patients should be counseled that they are at similar risk for decompression sickness (DCS) as those who do not have PFOs and should continue to take routine precautions.