Catheter Atrial Septostomy For Transposition of Great Artery | Clinical Notes.
Ayinla Daniel. Rn, Rctn.
This brief clinical note contains basic Information about TGA (Transposition of Great Arteries), it will give you an idea and make you understand the foundational principles of it’s pathophysiology.
Brief Anatomy & Physiology of The Great Blood Vessels.
The great arteries (Pulmonary artery & Aorta) are the two large arteries that transport blood away from the two major chambers of the human heart (the left & right ventricles).
These two blood vessels play very vital roles in maintaining normal hemodynamics in the cardiovascular system; with the pulmonary artery transporting deoxygenated blood from the right ventricles to the lungs for oxygenation and the aorta transporting oxygenated blood from the left ventricles to the systemic circulation.
Transposition of The Great Blood Vessels
In transposition of great blood vessels there is an anatomical anomaly where these two great blood vessels switch their positions (transposed) I.e the aorta that should connect the left ventricle to the systemic circulation now takes it’s origin from the right ventricle and the pulmonary artery that should connect the right ventricle to the lungs now takes it’s root from the left ventricle.
This transposition makes it difficult/impossible for the systemic circulation to get oxygenated blood, since the aorta is no longer connected to the left ventricle (where blood is meant to be oxygenated) but is connected instead to the right side of the heart which is responsible for pumping deoxygented blood.
While the pulmonary artery which is meant to transport deoxygented blood is directly connected to the left ventricle which conveys oxygenated blood; the pulmonary artery now carries blood directly to the lung preventing oxygenated blood from getting to the systemic circulation (pulmonary circulation is a closed system, which only empties into the left atrium through four great veins).
Cathether Atrial septostomy
In Cathether Atrial septostomy, the goal is to temporarily create a channel for oxygenated blood to flow to the systemic circulation by creating a route on the atrial septal/wall through the foramen ovale, allowing trapped blood in the left side which is bypassing the systemic circulation due to the abnormal position of the pulmonary artery to mix with blood in the right side which is carried by the abnormally positioned aorta to the systemic position.
This is done before surgery is carried out (arterial switch operation) to reposition these great blood vessels.
A catheter with a balloon tip, is passed through the foramen ovale (which is still patent during the first seasons of life) (in the Cath lab via Cardiac Catheterization) and inflated to open the hole, allowing blood to flow from the left side to the right side, improving symptoms.
Being a congenital disorder (occurs mainly in the new born), detection is normally after birth (within days and weeks), with cyanosis (cyanotic heart defect) as the most profound clinical manifestation that can be observed, it is life-threatening and prompt intervention is needed to improve outcomes.
This is a very brief clinical note, aimed at giving you an idea of what TGA (Transposition of Great Arteries) is, I hope to write another article that will address this subject with more details.