Folia Morphol. Vol. 71, No. 4, pp. 245–251 Copyright © 2012 Via Medica O R I G I N A L A R T I C L E ISSN 0015–5659 www.fm.viamedica.pl Posterior intercostal artery tortuosity and collateral branch points: a cadaveric study E. Shurtleff1, A. Olinger2 1Clinical Anatomy Fellow, Kansas City University of Medicine and Biosciences, Kansas City, MO, USA 2Department of Anatomy, Kansas City University of Medicine and Biosciences, Kansas City, MO, USA [Received 5 July 2012; Accepted 6 August 2012] Publications report observing tortuosity in the posterior intercostal arteries of elderly patients. Studies also describe the size and course of the collateral inter- costal arteries. This information is clinically significant when performing thora- centesis and video-assisted thorascopic surgery. To the best of our knowledge, no studies have examined arterial tortuosity or described collateral artery ori- gins relative to bony landmarks. The purpose of this study was to define a safe surgical zone for thoracic access using palpable external bony landmarks. A total of 348 intercostal spaces (3rd–8th) of 29 male and female embalmed ca- davers were dissected from the vertebral body to the mid-axillary line to ob- serve the posterior intercostal artery and its collateral branch. The origins of the collateral intercostal arteries relative to the midline of thoracic spinous process- es were measured. Mild to moderate tortuosity (arterial curves covering 25– –50% of the intercostal space) was observed in at least one posterior intercos- tal artery in the majority of cadavers. The origins of the collateral intercostal arte- ries were variable relative to the midline. Additional collateral intercostal arte- ries distal to the primary collateral branch were observed, most commonly in the 5th intercostal space, which is used in video-assisted thorascopic surgery and thoracentesis. Tortuosity is common in the 3rd to the 8th posterior intercos- tal arteries, especially in individuals over the age of 60 years. Given the findings of this study, we recommend that any procedure involving placement of a surgi- cal instrument into these intercostal spaces does so at least 120 mm lateral to the midline of the spinous processes. We also recommend pre-procedure ultrasound (intercostal scan) of the posterior and collateral intercostal arteries when per- forming non-emergent thoracentesis and video-assisted thorascopic surgery, par- ticularly in patients over 60 years of age. (Folia Morphol 2012; 71, 4: 245–251) Key words: thoroscopy, thoracic surgery INTRODUCTION rax have existed in the literature since 1970 [4], but Thoracentesis and thoroscopy are well-estab- at present there is no comprehensive description of lished procedures currently in widespread use, and the posterior intercostal and collateral vascular ana- while haemothorax is a rare complication, it is seri- tomy [3]. Another procedure gaining prevalence in ous when it occurs. The major cause of haemotho- clinical use for resection of lung tumours is video- rax in thoracentesis is laceration of the posterior in- -assisted thoracic surgery (VATS). Haemorrhaging tercostal artery (ICA) or its collateral branches [8, 10]. secondary to trocar penetration of the chest wall is Reports of ICA laceration and subsequent haemotho- one of the most common complications associated Address for correspondence: Dr. A. Olinger, Department of Anatomy, Kansas City University of Medicine and Biosciences, Kansas City, Missouri, USA, e-mail: [email protected] 245 Folia Morphol., 2012, Vol. 71, No. 4 with VATS, and it may be severe [6–8]. One specific vations were made: 1) With the cadaver prone, the patient population at increased risk for haemotho- distance from the midline of the spinous processes rax secondary to chest wall penetration are the eld- to the point where the collateral branch originates/ erly, as their posterior intercostal and collateral ar- /branches from the posterior ICA was measured; teries are known to become more tortuous with ad- 2) Also with the cadaver prone, the distance from vancing age, thereby decreasing the safe access area the midline to the point where the collateral branch within the intercostal space (ICS) [1, 10]. reaches the superior edge of the rib below the re- The current recommended approach to the tho- spective ICS was measured; 3) The incidence that racic cavity in thoracentesis is 5–10 cm lateral to the the posterior ICA produces an additional collateral spine in the 3rd–8th ICSs [9]. In VATS, access to the branch was tabulated; 4) Again with the cadaver thoracic cavity is achieved with trocars at three sites: prone, the distance from the midline of the spinous 1) in the 7th or 8th ICS between the mid-axillary and processes to the origin/branch point of the additional posterior axillary line, 2) in the 5th ICS at the anterior collateral branch was measured. We defined an ad- axillary line, and 3) in the 5th ICS 2 to 3 cm medial to ditional collateral branch of the posterior ICA as the scapula [5]. It was the objective of this study to those arteries observed originating from the poste- find the mean distance from palpable bony land- rior ICA and descending to the superior margin of marks, the spinous processes of T3–T8, to the branch the rib below, and having the same outside diame- points of the collateral branch of the posterior ICA, ter as the more medial and typical collateral branch. the branch point of additional collateral branches of With the cadaver supine, white-headed marking the posterior ICA, and points of maximum tortuosity pins 1 mm in diameter were placed at the points of within the ICS of T3–T8. This information will hope- collateral posterior ICA origin/branch points. Red- fully define a surgical safe-zone for thoracic access headed marking pins 1 mm in diameter were placed using external landmarks that may be palpated in- at the point where the collateral posterior ICA reached traoperatively, thereby decreasing the incidence of the superior margin of the inferior rib of the respec- haemothorax in thoracentesis and VATS procedures. tive ICS (Fig. 1). White-headed marking pins 1 mm in diameter were also placed at the origin/branch points MATERIAL AND METHODS of any additional collateral arteries (Fig. 2). Twenty-nine embalmed human cadavers (16 ma- Posterior intercostal artery tortuosity le/13 female) were selected for the study. The aver- age age of the specimens was 71 years, with With respect to the tortuosity of the posterior 23 specimens greater than the age of 60 and 6 less ICA the following measurements and observations than the age of 60. The 3rd to the 8th ICS of each were made: 1) The vertical distance of tortuosity cadaver was dissected bilaterally, giving a total of occupying the ICS as well as the vertical distance of 348 dissected ICSs. The dissection involved remov- the entire ICS was measured so the percentage of ing the anterior thoracic wall to the mid-axillary line tortuosity occupying the ICS could be calculated; bilaterally and removing the thoracic viscera, as well 2) With the cadaver prone, the distance from the as the parietal pleurae and innermost intercostal midline to the site of maximum tortuosity of the muscles. To expose the posterior ICA and their col- posterior ICA was measured; 3) The incidence that lateral branches, the intercostal nerves were care- the tortuosity of the posterior ICA occupied more fully retracted and removed. Care was also taken than 30% of the ICS was tabulated as this repre- not to disturb the fat surrounding the underlying sents exposure and therefore vulnerability of the vessels or alter their course through the ICS. artery in the ICS; 4) The incidence that posterior in- tercostal arterial tortuosity was present in a cada- Posterior intercostal artery mean outside diameter ver over the age of 60 was tabulated. We defined The outside diameter of the posterior ICA was maximum tortuosity as the point at which the pos- measured at the costal angle in the 3rd–8th ICSs bila- terior ICA deviated farthest inferiorly into the ICS terally using a flexible fiberglass ruler. The diameters from its typical course in the costal groove. were averaged for each individual ICS bilaterally. Yellow-headed marking pins 1 mm in diame- ter were placed at the point of maximum arterial Posterior intercostal artery collateral branch tortuosity to mark the inferior margin of the su- With respect to the collateral branch of the pos- perior rib and the superior margin of the inferior terior ICA the following measurements and obser- rib. Measurements were then taken in millime- 246 E. Shurtleff, A. Olinger, Posterior intercostal artery tortuosity and collateral branch points Figure 1. Measurements for the collateral branch of the posterior intercostal artery. Distance was measured from the midline to the white pin, representing the distance from the midline to the origin/branch point of the collateral branch from the posterior intercostal artery. Distance was measured from the midline to the red pin, representing the distance from the midline to the point where the collateral branch reaches its destination on the superior edge of the rib inferior to each respective intercostal space. Figure 2. Identification and measurement of additional collateral branches from the posterior intercostal arteries. White-headed pins represent the origin/branch point of the collateral branches of posterior intercostal arteries as well as any additional collateral branches from the posterior intercostal arteries. Distance was measured from the midline to the more lateral white pin, representing the distance from the midline to the origin/branch point of the additional collateral branch from the posterior intercostal artery. tres to calculate the percentage of the ICS tra- pins passing in an anterior to posterior direction versed by the tortuous artery below the costal through the erector spinae and intercostal muscles.