Human left atrial appendage anatomy and overview to its clinical significance

Abstract

Objective: The left atrial appendage (LAA) is an important anatomic region since it is a source of thromboembolism in patients with atrial fibrillation. Although this anatomic and clinical relation it has received little attention until recent years. Methods: This descriptive laboratory study was performed in 56 hearts of adult formalin fixed cadavers. The morphological characteristics of LAA were recorded. The distances between the orifices of left superior pulmonary veins (LSPV), circumflex artery, left anterior descending (LAD) artery, mitral valve and LAA were also measured in this study. Results: The morphological appearance of the LAA was classified into two different ways. There were two types according to the first classification: slender like a crooked finger (in 73.2%) and stump-like (in 26.8%). The lobe number of LAA was two in 64.3% specimens and three in 35.7%. The types of LAA were Cactus (24%), Chicken Wing (12%), Windsock (38%) and Cauliflower (26%) according to the second classification. The LAA orifice was oval-shaped in 37.5% and round-shaped in 62.5%. The bridge on the orifice was determined in one specimen. The longest diameter of LAA orifice was 16.5±4 mm. The presence of accessory left atrial appendage was observed in one specimen. The distance between LAA orifice and oval fossa was 27.5±5.5 mm. Conclusion: We highlighted the anatomic features of LAA and LAA orifice. LAA diameters, shape and the relation between neighboring structures in relation to atrial fibrillation and surgical approaches were discussed. (Anadolu Kardiyol Derg 2013; 13: 566-72) Key words: Anatomy, atrial fibrillation, left atrial appendage, left atrium, thrombus Original Investigation Özgün Araşt›rma 566ÖZET Amaç: Sol aurikula atriyal fibrilasyonlu hastalarda tromboemboli nedeni olduğu için önemli bir anatomik bölgedir. Bu anatomik ve klinik ilişkiye rağmen son yıllara kadar az dikkate alınmıştır. Yöntemler: Bu tanımlayıcı laboratuvar çalışmasında 56 adet formalinle fikse edilmiş kalp üzerinde çalışıldı. Sol aurikulanın morfolojik özellikleri kaydedildi. Bu çalışmada üst pulmoner venler, sirkumfleks arter, sol ön inen arter ve mitral kapak ile sol aurikula açıklığı arası da ölçüldü. Bulgular: Sol aurikulanın morfolojik görünümü iki farklı şekilde sınıflandırıldı. İlk sınıflandırmaya göre iki tip mevcuttu: İnce çomak parmak şekilli (%73,2) ve kütük şekilli (%26,8). Sol aurikula lob sayısı ise olguların %64,3'ünde iki iken %35,7'sinde üç idi. İkinci sınıflandırmaya göre sol atriyal aurikula (SAA) tipleri, Kaktüs (%24), Tavuk Kanadı (%12), Rüzgar Hortumu (%38) ve Karnabahar (%26) şeklindeydi. Sol aurikula açıklığı %37,5 olguda oval şekilli iken %62,5 olguda yuvarlak şekilli idi. Sol aurikula açıklığının en uzun çapı 16,5±4,0 mm olarak bulundu. Aksesuvar sol aurikula bir olguda görüldü. Sol aurikula açıklığı ve fossa ovalis arası uzaklık ise 27,5±5,5 mm idi. Sonuç: Sol aurikula ve sol aurikula açıklığının anatomik özellikleri aydınlatıldı. Sol aurikula açıklığının çapı, şekli ve çevre yapılarla ilişkisinin, atrial ...

Left Atrial Anatomy Relevant to Catheter Ablation

“…In autopsy specimens and imaging studies, the LAA ostium is usually elliptical or round and in elliptical-shaped variant and its long axis is obliquely orientated relative to the mitral annulus [52, 53]. The LAA interior surface is lined by complicated network of fine pectinate muscles.…”

“A bend in time”: Shaping the sheath facilitates left atrial appendage closure

“…One of the potential reasons for the learning curve is that the LAA is a three-dimensional entity. There are variations in shape, lobe number, and orifice diameter [5]. Some shapes, such as "cauliflower" shape, may be more associated in strokes in patients with low CHADS 2 scores [6].…”

Left atrial appendage: anatomy and imaging landmarks pertinent to percutaneous transcatheter occlusion

“…In this study7 a lobe was anatomically defined as: (1) a visible ‘outpouching’ from the main tubular LAA, often demarcated externally by a ‘crease’; (2) able to accept a 2 mm probe internally; (3) possibly associated with a change in the main tubular LAA direction; and (4) lying in a different plane from the main tubular LAA. In a recent autopsy study, two and three lobes were observed in 64.3% and 35.7% of specimens, respectively 8. Accurate sizing of the LAA and knowledge of its gross morphological features are crucial to reduce the frequency of complications associated with percutaneous LAA occlusion (box 1).…”

“…In autopsy specimens and imaging studies, the LAA ostium is usually elliptical or round and in elliptical-shaped variant, its long axis is obliquely orientated relative to the mitral annulus 8 11. The mean longest diameter of the LAA orifice is 16–17 mm and the mean shortest diameter is around 10–11 mm 8 11.…”

“…The mean longest diameter of the LAA orifice is 16–17 mm and the mean shortest diameter is around 10–11 mm 8 11. Wang et al 6 performed a cardiac CT study in patients with or without AF and classified the orifice into five types: oval (68.9%), foot-like (10%), triangular (7.7%), water drop-like (7.7%), and round (5.7%).…”