Atrial Septal Defect (ASD)
Atrial septal defect (ASD)
In an atrial septal defect (ASD), a hole in the atrial septum is flowing oxygen-rich blood from LA to RV. The RA, RV and ultimately the lungs, therefore has more volume of blood to process. ASD is the volume load on the RV.
|ASD is to be divided into four types:|
|ASD type I||Ostium primum defect||In the basal septum t.p.v. atrioventricular ventricular transition|
|ASD type II||Ostium secundum defect||In the middle of the atrial septum, the fossa ovalis area.|
|ASD type III||Sinus venosus defect||At the entrance of both the VCS and the VCI|
|Coronary sinus defect||Coronary sinus defect||Compound coronary sinus with LA.|
ASD can manifest at any age. An ASD comes in 9% of all congenital heart defects, but for the most common congenital heart disease often only reflects (30%) in adulthood.
|Most common ASD|
|ASD II||70 %|
|ASD I||15 %|
|Sinus venosus defect 1||5 %|
|Coronary sinus defect||Rare|
Patent Foramen Ovale (PFO)
A patent foramen ovale, abbreviated to PFO, has a functional defect in the atrial septum, in contrast to an ASD that has an anatomical defect. The septum primum and septum secundum develop from different edges in the embryonic atria. However, the septum secundum does not form a closed portion, there always remains an opening between the two septa. At birth, the inter-atrial pressure is changed and is pressed against the two septa. In 15-35% of the population, there still remains a small opening. A PFO is in fact an incomplete fusion of the septum primum and septum secundum .
A PFO is involved with a number of other pathologies such as cerebrovascular accident (CVA), Transient Ischemic Attack (TIA) , Caisson Disease (Decompression sickness among divers) , Platypneu-orthodeoxiesyndrom and Migraine. There is a direct relationship between the size of the shunt and the risk of stroke .
A PFO can be demonstrated with the aid of contrast by means of a saline solution. There is a PFO if within three cardiac cycles you see a crossing from right to left after administration of contrast.
The number of bubbles in one frame can be categorized in size of opening:
|Size of PFO|
|Narrow opening||< 10 contrast bubbles in LA|
|Excessive opening||10-20 contrast bubbles in LA|
|Grand opening||> 20 contrast bubbles in LA|
|Crossing contrast to PFO |
|Localization of defect||Color doppler + possible contrast. Where in IAS?|
|Instructions for volume overload||Dimensions RF + RA. Question of dilation?|
|Evidence of pulmonary hypertension||SPAP. See high pressures?|
Click here for Qp/Qs calculation.
Example of ASD
|Large ASD type II||Contrast crossing at ASD type II|
|Closure of ASD occurs with Closure Device. Endocardial tissue grows over the device. |
- Error fetching PMID 21078836:
EC Cheriex, "Left atrium and investigated", Hamer/Pieper, "Practical echocardiography", (2006), 1st edition 2nd edition, Wood, Bohn Stafleu of Loghum, p.42-53.