Transcatheter closure of right-to-left interatrial shunts to resolve hypoxemia.

BACKGROUND

Right-to-left interatrial shunts through an atrial septal defect or patent foramen ovale may result from congenital and acquired conditions. Right-to-left shunts may occur with normal pulmonary artery pressure and resistance as in right ventricular outflow tract obstruction leading to hypertrophy and reduced diastolic function, in right ventricle ischemia, myocarditis or cardiomyopathy and in orthodeoxia-platypnea syndrome.

METHODS

We have tested the tolerance of trans-catheter closure of right-to-left interatrial shunts in 5 selected patients in whom the morphology and hemodynamics implied that it would be well-tolerated and improve functional capacity. Right-to-left shunt was demonstrated in 5 profoundly cyanotic patients by trans-thoracic and trans-esophageal echocardiography with intravenous injection of agitated saline. The patients were catheterized for hemo-dynamic study and tested for tolerance of transient balloon occlusion of the defects.

RESULTS

Diastolic right ventricular dysfunction with elevated end-diastolic pressure was the primary cause of right-to-left shunt. Most shunts occur via atrial septal defects. Patients' ability to tolerate temporary balloon occlusion of the defects predicted a favorable outcome following permanent device occlusion. Cyanosis resolved in all patients following closure of the defects without congestive right heart failure. A marked improvement in functional capacity was observed in 4 patients. One died of preinterventional hypoxic brain damage.

CONCLUSION

Transcatheter closure of right-to-left shunts is well-tolerated and a rewarding approach. It should be applied in selected patients following careful morphologic and hemodynamic evaluation. Tolerance of temporary occlusion of the defect is predictive of a favorable procedural outcome.