Right atrial isomerism | Left atrial isomerism | |
Situs | ||
Bilateral right-sidedness | Bilateral left-sidedness | |
Abdomen | ||
Spleen | No spleen (asplenia) | More than one spleen (polysplenia) |
Liver | Symmetrical and horizontal | Bilobed, may be symmetrical, but more often to one side |
Stomach | Near midline (right or left) | Usually right-sided |
Heart and vessels | ||
Cardiac position | Mesocardia common; can be on either side | Mesocardia rare; generally on either side |
Systemic venous vessels | ||
Superior vena cava | Bilateral: One to each atrium | May be bilateral: One to each atrium (can be via coronary sinus) |
Coronary sinus | Absent | Generally present |
Inferior vena cava | Present; can connect to either atria but is always on the same side as DAo | Usually interrupted with azygos continuation |
Atria | ||
General | Bilateral right atria | Bilateral left atria |
Sinoatrial node | Bilateral with one dominant (usually inferior P wave axis) | Absent coronary sinus rhythm |
Septum | Usually large primum and secundum ASD | Highly variable, from intact septum to common atrium |
Atrioventricular valves | Single (AVSD type) or atresia of one | Two valves or AVSD type |
Pulmonary veins | Generally extracardiac TAPVR | Directly to atria |
Ventricles | ||
Position | Inverted | D-looping |
Ventricular septal defect type | Canal type (inlet) | Membranous or canal type |
Great arteries | ||
Position | Malposed (approximately 95%); DORV (approximately 5%) | Generally normal, occasional DORV and rare malposition |
Pulmonary outflow obstruction | Severe pulmonary stenosis or atresia in >90% | Pulmonic stenosis is unusual |
Left-sided obstruction | Rare | Common (MS, AS, CoA) |
Other thoracic organs | ||
Bronchi | Both are eparterial | Both are hyparterial |
Lungs | Bilateral trilobed | Bilateral bilobed |
Do you want to add Medilib to your home screen?