Identification and quantitative analysis of branching networks of the posterior intercostal arteries.

Morphological and anatomical characteristics of the posterior intercostal arteries have revived interest in their branching networks. Collateral supply between intercostal spaces is extensive due to anastomoses, although the data about the quantitative description of the branching networks in the existing literature are rather limited. The presence of collateral network between branches of the posterior intercostal arteries has been studied on forty-three Thiel-embalmed human cadavers. A network-based approach has been used to quantify the measured vascular branching patterns. Connections between branches of the same or adjacent posterior intercostal artery were identified. The non-anastomosing branches coursing in the intercostal spaces were also observed and their abundance was higher in comparison to anastomosing vessels. A quantitative analysis of collateral branching networks has revealed the highest density of vessels located close to the costal angle and most of the anastomosing branches were found between the fourth and tenth intercostal space. Anastomoses within the same posterior intercostal artery were more frequent in higher intercostal spaces, whereas in the lower intercostal spaces more connections were established between neighboring intercostal arteries. Our results indicate that due to abundant collateral contribution the possibility to cause an ischemic injury is rather low unless there is considerable damage to the blood supply of the trunk or surgical complication leading to ischemia or necrosis. Analyzing the proper course of collateral contributions of the posterior intercostal arteries may support further directions regarding the safest place for percutaneous transthoracic interventions, thoracocentesis, and lung biopsy.