Extreme eccentric canal type pectus excavatum: morphological study and repair techniques.

Objective: Extreme eccentric canal type pectus excavatum (Grand Canyon type, GC, Type 2A3), is a distinct morphological variation, characterized by an eccentric longitudinal canal. Due to the extent of depression and asymmetry, repair is often challenging with the minimally invasive technique. Following, we present its morphologic characteristics and evaluate repair techniques according to morphology type.

Methods: Extreme eccentric canal type pectus excavatum is an eccentric, long canal-like chest wall depression from the infra-clavicle to lower chest. Among 851 patients who underwent pectus excavatum repair from 1999 to 2007, 112 patients (13.2%) had the eccentric canal type. Morphologic type and repair techniques were evaluated; results were assessed by pectus indices (depression index (DI), asymmetry index (AI), and eccentricity index (EI)).

Results: Of the asymmetric cases, 31% (112/361) were the eccentric canal type. Female proportion (male to female ratio=2.3) was higher than in general pectus excavatum (4.1, p<0.05). Young female adults were more frequently affected (8/17, 47%, p<0.05). Repair techniques included asymmetric bar (n=97, 86.6%), seagull bar (n=53, 47.3%), crest compression (n=13, 11.6%), and parallel bar (n=79, 70.5 %) techniques. Pectus indices changes were: DI (pre 2.89 to post 1, p<0.01), AI (pre 1.11 to post 1.03, p<0.01), and EI (pre 1.69 to post 1, p<0.01). AI change represented asymmetric to symmetric correction.

Conclusions: Extreme eccentric canal type pectus excavatum represents a distinctive morphology and requires special techniques for repair. Post-repair symmetry can be achieved by an asymmetric bar technique. Upper chest wall depression can be corrected by a parallel bar technique. Protruding ridge was relieved by a seagull bar or crest compression technique.