JUXTAPOSITION OF THE MORPHOLOGICALLY LEFT ATRIAL APPENDAGE IN SOLITUSAND INVERSUS ATRIA - A STUDY OF 18 POSTMORTEM CASES

Juxtaposition of the morphologically left atrial appendage (JLAA) was analyzed for the first time primarily morphologically, rather than pri marily positionally. In a series of 18 postmortem cases, JLAA with sol itus atria occurred in 16 (89%) cases, and JLAA with inversus atria wa s found in 2 (11%) cases. JLAA with solitus atria was always right-sid ed, whereas JLAA with inversus atria was left-sided. Thus the sidednes s of the malposed (juxtaposed) LAA depended on the atrial situs, not o n the type of ventricular loop (contrary to what was formerly thought) . The anatomic features associated with JLAA are essentially the oppos ite of those with JRAA. JLAA was characterized by left atrial outlet o bstruction (69%), left ventricular hypoplasia (67%), and aortic outflo w tract obstruction (39%). JLAA usually has a hypoplastic left ventric le and normal conus, whereas JRAA typically has a hypoplastic right ve ntricle and abnormal conus.