A Case Report of an Unusual Axillary Artery Branching Pattern with Clinical Implications

The axillary artery, a critical vascular structure supplying the upper limb, exhibits significant anatomical variability that can profoundly impact surgical outcomes. The case presented in this study highlights an unusual branching pattern of the AA, where the second part gives rise to the LTA, SA, and PCHA. This variation underscores the importance of detailed preoperative planning and awareness of such anomalies to prevent complications during surgical procedures.

The observed variation likely results from altered embryonic angiogenesis. The axillary artery develops from the persistence of the 7th intersegmental artery and the regression of other primitive pathways. Any deviation in this process can lead to anatomical variations, as seen in this case [8]. Considering another factor causing variations in vessels, abnormal pathways during vascularization, and defects around the related tissues are also noteworthy. [1] Understanding the embryological basis of these variations can provide insights into their occurrence and help predict potential complications.

While variations in the third part of the axillary artery are more common, occurring in 28–33% of individuals, anomalies in the second part are less frequent, reported in only 2–12% of cases. [11] This highlights the uniqueness of the observed branching pattern and emphasizes the need for comprehensive anatomical knowledge during surgical planning. Recognizing these variations is essential for avoiding complications and ensuring optimal surgical outcomes.

Previous studies have discussed the separation of the common trunk from the posterior part of the AA. [12, 13] Notably, the SA originates from the 2nd part of the AA in 4% of cases, often arising alongside the PCHA in a common trunk, as observed in 30% of cases, similar to our study. [1]

The common trunk of the 2nd part of the AA could give off several branches. For instance, Srimathi T. reported a common trunk from the 2nd part of the AA, which was the origin of the TAA, the LTA, the SA, and the PCHA. [13] Similarly, Bhat et al. described a case with a common trunk dividing into the TAA, the LTA, the SA, and the PCHA, also arising from the 2nd part of the AA. However, in our study, the TAA arose separately from the second part of the AA. Additionally, Bhat et al. noted that the ACHA originated from the third part of the AA, [14] which was absent in our case.

Our findings of the ACHA absence in the AA represent a significant anatomical variation. While the ACHA is classically described as a consistent branch of the AA third part, supplying the humeral head and periosteum, its absence in our study challenges conventional anatomical models. Other studies have reported similar variations. Patil et al. [5] and Kanaka S et al. [6] observed a common trunk from the second part of the AA that divided into the TAA, SA, LTA, PCHA, and TDA in 15% of cases. Muraleedhar B described a common trunk originating from the second part of the AA, giving rise to the SA, ACHA, PCHA, and profunda brachii artery (PBA). [12] Ezzati et al. reported a case with a common trunk that gave rise to the LTA, SA, and muscular branches. [15]

Patil et al. identified a common trunk for the SA, ACHA, PCHA and PBA (branch of the brachial artery), which originated from the first part of the AA. [5] Other studies by Saeed et al. and Vijaya et al. noted common trunks from the third part of the AA giving rise to various branches. [16, 17] Saeed et al. reported that the subscapular-circumflex humeral trunk arises from the third part of the AA in 3.8% of cases. [16] Another study found that the SA originates from the first part of the AA in 0.6% of cases, from the 2nd part in 15.7%, and from the 3rd part in 79.2%. [1] In our case report, the SA arose from the second part of the AA.

In the axillary region, tumors, abscesses, injuries, and lymph nodes are frequently seen. Dissection of axillary lymph nodes is necessary in some surgical procedures, the most significant of which is breast cancer. [18] Understanding vascular variability is crucial given the increasing use of invasive diagnostic and therapeutic methods in cardiovascular patients. Understanding these differences is necessary for reconstructive surgery in cases involving aneurysms and injuries to the AA and its branches.

Athletes, particularly baseball pitchers, are at risk of developing AA aneurysms due to repetitive strain on the artery. This can lead to segmental dissection, localized hyperplasia of the tunica intima, and an increased risk of thrombosis and distal embolism. [19] In cases of chronic shoulder dislocation, the AA is susceptible to laceration and rupture. Awareness of any aberrant branches is critical to prevent surgical bleeding during attempts to reduce these dislocations. Ignoring these variations can result in significant complications, emphasizing the importance of thorough anatomical knowledge in surgical planning. [1]

Advanced imaging techniques, such as contrast arteriography and MRI, are essential for identifying these variations and planning surgical interventions. By integrating anatomical knowledge with imaging, clinicians can mitigate risks associated with axillary artery variations and ensure optimal patient care. [20]