Patent foramen ovale
The foramen ovale in the interatrial septum normally develops into the fossa ovalis when the flaps of the atrial septa primum and secundum normally fuse during development. The foramen ovale remains patent if there is incompletely fusion. This variant occurs in 25-33% of adults 1,2. The prevalence may decrease with advancing age.
Patent foramen ovales/foramina ovalia are subdivided into:
- probe-patent foramen ovale
- patent foramen ovale
A "probe patent" foramen ovale is defined as a defect in the fossa ovalis that would be revealed with instrument probing.
A patent foramen ovale has been associated with paradoxical embolism and ischemic stroke because of the potential for a venous thromboembolism to pass from the right atrium to the systemic circulation, bypassing the lungs.
PFOs are small enough to be haemodynamically insignificant.
- may be detected on a "bubble study" (IV injection of agitated saline); the contrast material appears in the left atrium before the normal time
- abnormal communication of contrast material between the atria through a channel-like tunnel in the interatrial septum
- a channel-like tunnel alone is a normal variant of the fossa ovalis, and is not diagnostic
Contrast-enhanced cardiac MRI
- not a first-line study, but may be diagnosed by visual assessment or computation of signal–time curves in the pulmonary vein and the left atrium 3
A patent foramen ovale can be differentiated from an atrial septal defect because a PFO takes a tunneled intraseptal course, or with the presence of a flap valve on the left atrial side of the foramen 2.
Treatment and prognosis
Closure devices, both surgically open and percutaneous, have been developed and are currently implemented in some centers for PFO.
- 1. Fuster V, Walsh R, Harrington R. Hurst's the heart. McGraw-Hill Professional. ISBN:0071636463. Read it at Google Books - Find it at Amazon
- 2. Halpern EJ. Clinical Cardiac CT. Thieme. ISBN:1604063750. Read it at Google Books - Find it at Amazon
- 3. Mohrs OK, Petersen SE, Erkapic D et-al. Diagnosis of patent foramen ovale using contrast-enhanced dynamic MRI: a pilot study. AJR Am J Roentgenol. 2005;184 (1): 234-40. doi:10.2214/ajr.184.1.01840234 - Pubmed citation
- 4. Kim YJ, Hur J, Shim CY et-al. Patent foramen ovale: diagnosis with multidetector CT-comparison with transesophageal echocardiography. Radiology. 2009;250 (1): 61-7. doi:10.1148/radiol.2501080559 - Pubmed citation
Congenital heart disease
There is more than one way to present the variety of congenital heart diseases. Whichever way they are categorised, it is helpful to have a working understanding of normal and fetal circulation, as well as an understanding of the segmental approach to imaging in congenital heart disease.
congenital heart disease
- normal relationship between chambers and valves
- atrioventricular valves
- outflow tract
- great vessels
- venous inflow
- anomalous valves
- abnormal relationship of chambers and valves
- atrioventricular abnormality
- great vessel connection abnormality
- conotruncal cardiac anomalies
- pentalogy of Cantrell
- Shone syndrome
- congenital heart disease - chest x-ray approach
surgical repairs (mnemonic)
- arterial switch procedure
- Blalock-Taussig shunt
- double switch procedure
- Fontan procedure
- Glenn procedure
- Mustard repair
- Norwood procedure
- Pott shunt
- pulmonary artery banding
- Rastelli procedure
- Sano shunt
- Senning repair
- total repair of tetralogy of Fallot (TOF)
- unifocalisation procedure
- Waterston shunt