Aortic isthmus
The aortic isthmus is the part of the aorta just distal to the origin of the left subclavian artery at the site of the ductus arteriosus.
This portion of the aorta is partly constricted in the fetus because of the lack of flow within the aortic sac and ascending aorta. It marks the partial separation of fetal blood flow derived from the right and left ventricles.
History and etymology
Derived from the Ancient Greek ισθμος (isthmos) meaning a neck of land 3.
Related pathology
- most common anatomical area of traumatic thoracic aortic injuries in patients surviving long enough to be imaged 1
- the site of the ductus diverticulum which is an anatomical variant of the aorta that should be differentiated from an aortic pseudoaneurysm in the setting of trauma 2
- the aortic isthmus index (isthmus flow index) is used in obstetric Doppler as a marker of raised placental resistance and fetal growth restriction 4
Related Radiopaedia articles
Anatomy: Thoracic
- thoracic skeleton
- thoracic cage
- thoracic spine
- articulations
- muscles of the thorax
- diaphragm
- intercostal space
- intercostal muscles
- variant anatomy
- spaces of the thorax
- thoracic viscera
- tracheobronchial tree
-
lungs
-
bronchopulmonary segmental anatomy (Boyden Classification) (mnemonic)
- left lung
- right lung
- variant anatomy
- lung parenchyma
- hilum
- pleura
-
bronchopulmonary segmental anatomy (Boyden Classification) (mnemonic)
-
heart
- cardiac chambers
- heart valves
- pectinate muscles
- cardiac fibrous skeleton
-
coronary arteries
- coronary arterial dominance
- myocardial segments
-
left main coronary artery (LMCA)
- ramus intermedius artery (RI)
-
circumflex artery (LCx)
- obtuse marginal branches (OM1, OM2, etc))
- Kugel's artery
-
left anterior descending artery (LAD)
- diagonal branches (D1, D2, etc)
- septal perforators (S1, S2, etc)
-
right coronary artery (RCA)
- conus artery
- sinoatrial nodal artery
- acute marginal branches (AM1, AM2, etc)
- inferior interventricular artery (PDA)
- posterior left ventricular artery (PLV)
- congenital anomalies
- innervation of the heart
- fetal circulation
- atrial septum
- endocardium
- myocardium
-
pericardium
- epicardium
- epicardial fat pad
- pericardial space
- oblique pericardial sinus
- transverse pericardial sinus
-
pericardial recesses
- aortic recesses
- pulmonic recesses
- postcaval recess
- pulmonary venous recesses
- pericardial ligaments
- esophagus
- thymus
- breast
- blood supply of the thorax
- arteries
- veins
- superior vena cava (SVC)
- inferior vena cava (IVC)
-
coronary veins
- cardiac veins which drain into the coronary sinus
- great cardiac vein
- middle cardiac vein
- small cardiac vein
- posterior vein of the left ventricle
- vein of Marshall (oblique vein of the left atrium)
- anterior cardiac veins
- venae cordis minimae (smallest cardiac veins or thebesian veins)
- cardiac veins which drain into the coronary sinus
- pulmonary veins
- thoracoepigastric vein
- lymphatics
- innervation of the thorax