Isolated injury to the internal mammary artery (IMA) is rare but potentially life-threatening if not promptly diagnosed and managed. Such injuries can result from penetrating or blunt trauma, or iatrogenic causes such as sternal wire insertion during cardiac surgery. Failure to identify and control the bleeding can lead to massive hemothorax, shock, and death. We present a case series of four patients with isolated IMA injuries following gunshot wounds, stab injuries, and cardiac surgery. Each case underscores the importance of early recognition, high clinical suspicion, and timely surgical intervention. Appropriate management through thoracotomy or sternotomy resulted in favorable outcomes in all cases
Injuries to the internal mammary artery (IMA) are uncommon but clinically significant, given the artery's anatomical course along the inner chest wall. These injuries are mostly associated with penetrating trauma, blunt chest trauma, or iatrogenic causes such as central venous catheterization or sternotomy closure during cardiac procedures. Due to the IMA's proximity to the pleura and mediastinum, injury can result in rapid accumulation of blood within the thoracic cavity, manifesting as hemothorax or even pericardial tamponade.
The diagnosis of IMA injury can be challenging, especially in hemodynamically stable patients or in settings where other thoracic injuries mask its presentation. A high index of suspicion is necessary when patients present with unexplained hemothorax, persistent bleeding after chest tube insertion, or sudden postoperative hemodynamic deterioration.
Although isolated reports of IMA injury exist in the literature, comprehensive case series remain limited. This study presents four cases of isolated IMA injury resulting from penetrating trauma or surgical procedures, highlighting clinical presentation, management, and outcomes. A review of pertinent literature is also included to contextualize our findings.
A 40-year-old male underwent elective mitral valve replacement surgery. The procedure proceeded uneventfully, and the sternum was closed using stainless steel wires. Upon arrival in the intensive care unit (ICU), however, the patient exhibited signs of hemodynamic instability, including tachycardia and hypotension. Serial laboratory tests revealed a declining hemoglobin level and hematocrit, accompanied by approximately 1000 mL of fresh blood drainage through the mediastinal chest tubes over the course of three hours.
Despite aggressive fluid resuscitation and escalating inotropic support, the patient’s condition continued to deteriorate. The decision was made to return him to the operating room for re-exploration. Upon reopening the sternum, a large volume of fresh blood and clots were evacuated. Careful inspection of the mitral valve repair site revealed no active bleeding. However, significant bleeding was identified from the left internal mammary artery, which had been partially torn by a sternal wire.
The artery was carefully dissected, and LIGA clips were applied both proximally and distally to control the hemorrhage. Four units of packed red blood cells were transfused intraoperatively. Hemostasis was achieved, and the sternum was closed again using stainless steel wires. Following the procedure, the patient stabilized hemodynamically, his inotropic support requirements decreased, and tachycardia resolved.
He was transferred back to the ICU and extubated 12 hours later. Chest tubes were removed after 48 hours once drainage became minimal. The remainder of his postoperative course was uneventful, and he was discharged on the seventh postoperative day in stable condition. On follow-up visits, he remained in good health.
A 30-year-old male presented to the trauma center two hours after sustaining a stab wound to the right lower chest during an altercation. He reported chest pain, shortness of breath, and minimal bleeding at the site of injury. On examination, his blood pressure was 90/60 mmHg, pulse rate was 120 bpm, and oxygen saturation was 98% on oxygen. A 2 x 3 cm wound was noted at the right lower chest, and auscultation revealed reduced air entry on the right side.
Initial chest X-ray showed a right-sided hemothorax, and a chest drain was inserted, immediately evacuating 1400 mL of blood. Continued bleeding was noted, and the patient was rapidly resuscitated with crystalloids and blood products. Given the ongoing blood loss and unstable vitals, urgent exploration was planned.
A median sternotomy was performed, revealing significant clotted and fresh blood in the right pleural cavity. The pericardium was intact. Active bleeding was traced to a torn right internal mammary artery (IMA). The artery was carefully dissected, ligated proximally and distally, and clipped. A 3 cm laceration was also identified in the right lung parenchyma, which was sutured. Hemostasis was achieved, and the sternum was closed with stainless steel wires. A total of six units of packed red blood cells were transfused during surgery.
Postoperatively, the patient was transferred to the ICU, extubated within 24 hours, and recovered without complications. Chest drains showed minimal output and were removed by postoperative day five. He was discharged in stable condition on the seventh postoperative day. At 18 months follow-up, he had resumed normal activities without any functional limitations.
A 28-year-old male was admitted after sustaining a gunshot wound to the right parasternal area. He complained of chest pain, difficulty breathing, and bleeding from the entry site. On arrival, his blood pressure was 80/50 mmHg, heart rate was 100 bpm, and oxygen saturation was 95% on supplemental oxygen. Physical examination revealed a 1 x 1 cm penetrating wound in the fourth intercostal space near the right parasternal border. Breath sounds were reduced on the right side.
Chest X-ray revealed a massive right-sided hemothorax. An intercostal drain was placed, evacuating 1500 mL of blood with ongoing bleeding. The patient was stabilized with fluids and blood transfusion, and emergent exploratory sternotomy was undertaken.
Intraoperatively, significant fresh and clotted blood was evacuated from the right pleural cavity. The pericardium was intact. Active bleeding was traced to a completely transected right internal mammary artery (IMA), which was ligated proximally and distally using LIGA clips. Additionally, bleeding from the right paravertebral vein was identified and controlled with ligation. The bullet was located and lodged in the thoracic spine vertebra.
Hemostasis was confirmed, and the sternum was closed using stainless steel wires. A right-sided pleural drain was inserted. The patient required seven units of packed red blood cells intraoperatively. He was extubated successfully the next day and transferred to the ward by postoperative day three. Chest tubes were removed by day five, and he was discharged in stable condition on the seventh postoperative day. Follow-up at 12 months showed complete recovery without functional impairments.
A 15-year-old male presented three hours after sustaining multiple stab injuries during an assault. He complained of chest pain but reported minimal external bleeding. He was alert and oriented on examination. Physical findings included one stab wound on the left anterior chest above the nipple and three stab wounds on the right chest: one near the sternal border in the fourth intercostal space, one below the nipple, and one posteriorly below the scapula.
Vital signs revealed hypotension (BP 78/36 mmHg), tachycardia (130 bpm), and 100% oxygen saturation on 5L/min oxygen. Auscultation showed decreased breath sounds on the right side. Chest X-ray demonstrated a right-sided hemopneumothorax and left-sided pneumothorax. Chest tubes were inserted bilaterally, with the right-sided tube draining 1.5 liters of blood. Despite initial resuscitation with colloids and blood products, bleeding persisted.
Emergency right thoracotomy was performed, revealing approximately 1 liter of fresh blood and clots. Active bleeding was identified from the right internal mammary artery, which was ligated proximally and distally with LIGA clips. No significant lung injury or pericardial breach was noted. After thorough irrigation and achieving hemostasis, the thoracotomy was closed in layers. (Fig. 1 and Fig. 2)
Figure 1. Bleeding from the torn site of IMA controlled with an angled hemostatic clamp
Figure 2. IMA after ligation and application of LIGA clips proximal and distal to torn site
Postoperatively, the patient was extubated after 12 hours in the ICU. Chest tubes were removed by postoperative day two, and he showed no respiratory compromise. He was discharged home in good condition on postoperative day six. Follow-up visits demonstrated full recovery without complications.
REVIEW OF LITERATURE
Isolated internal mammary artery (IMA) injuries, although rare, have been documented in various contexts, including penetrating and blunt chest trauma, as well as iatrogenic causes. Multiple case reports and small series highlight their clinical significance.
Curley et al. reported one of the earliest cases of pericardial tamponade and hemothorax secondary to a penetrating IMA injury. Their patient presented with hemodynamic collapse and required urgent sternotomy, during which the left IMA was identified and ligated, resulting in a favorable outcome (1).
Irgau et al. described an anterior mediastinal hematoma caused by blunt chest trauma leading to cardiac compromise. Surgical exploration revealed injury to the left IMA, which was successfully controlled. This case emphasized that non-penetrating trauma can also result in serious IMA injury (2).
Vinces et al. presented a case involving delayed hemothorax and pericardial tamponade secondary to stab wounds to the IMA. The patient deteriorated hours after the initial injury, requiring sternotomy and ligation of the injured artery. Their report highlighted the potential for delayed presentation and the importance of vigilance (3).
Holt et al. reported another instance of delayed tamponade due to penetrating trauma affecting the IMA. The case underlined the importance of post traumatic monitoring, as bleeding may initially be contained but progress to life-threatening tamponade (4).
Al Hassani et al. described a case of left IMA injury following penetrating trauma, necessitating resuscitative thoracotomy. Their patient arrived in profound shock, and thoracotomy revealed active hemorrhage from the IMA, which was ligated. The authors advocated for early thoracotomy in such cases (5).
Islam et al. discussed an isolated IMA injury following blunt trauma, managed through emergency thoracotomy. The patient exhibited persistent hemothorax unresponsive to chest tube drainage, prompting surgical intervention. Their findings emphasized the need to consider IMA injury when bleeding persists without an apparent source (6).
Miah et al. provided a literature review alongside their case of IMA injury managed with mini-thoracotomy. Their case supported the feasibility of minimally invasive approaches in stable patients but stressed that thoracotomy remains the gold standard in hemodynamically unstable individuals (7).
Zhang et al. reported a delayed hemothorax following blunt trauma-induced IMA injury. Their patient initially presented with minor symptoms but deteriorated over days. Contrast-enhanced CT facilitated diagnosis, and timely surgical intervention resulted in recovery (8).
Singh et al. presented a case of isolated right IMA injury following a penetrating chest wound. They demonstrated that small chest wounds near the sternal border could result in significant hemorrhage and emphasized prompt surgical control (9).
Johnson et al. described blunt trauma-induced IMA injury with mediastinal hematoma and hypotension. Surgical exploration identified the IMA as the bleeding source. Their case reinforced the need to include IMA injury in the differential diagnosis of blunt chest trauma with persistent bleeding (10).
These studies collectively underscore several key principles: the possibility of delayed presentation, the critical role of surgical exploration in hemodynamically unstable patients, and the necessity of maintaining a high index of suspicion in cases of unexplained hemothorax or mediastinal hematoma. Our case series contributes further evidence supporting early diagnosis and intervention in IMA injuries to optimize patient outcomes.
Isolated injury to the internal mammary artery (IMA) is a challenging clinical entity, not only because of its rarity but also due to its non-specific presentation. The internal mammary artery arises from the subclavian artery and travels down along the inner surface of the anterior chest wall. It lies posterior to the costal cartilages and gives off perforating branches, terminating in the sixth intercostal space by dividing into the superior epigastric and musculophrenic arteries. Given its anatomical location, the IMA is relatively protected, making injuries to it rare. However, in cases of penetrating trauma, or even during certain surgical procedures like sternotomy, it becomes vulnerable to damage.
When injured, the IMA can cause varying clinical presentations based on the extent of injury, the presence of hypotension, and the ability of surrounding structures such as the parietal pleura and transversus thoracis muscle to tamponade the bleeding. Hemothorax due to IMA injury may initially be contained but can become massive if undiagnosed, leading to shock and potential mortality. A complete transection of the IMA may paradoxically stop bleeding temporarily due to arterial spasm and hypotension but bleeding often resumes once blood pressure normalizes during resuscitation.
Diagnosis of IMA injury is complex. Imaging studies such as chest X-rays and CT scans are valuable in detecting hemothorax but often fail to specifically localize IMA injury. In stable patients, angiography may help in localizing and potentially embolizing the bleeding vessel. However, in unstable patients, imaging should not delay intervention. The mainstay of management in such scenarios remains surgical exploration—either thoracotomy or sternotomy—based on injury location and severity.
Management should ideally be performed by a cardiothoracic surgeon who is familiar with the anatomy and capable of managing the IMA and any associated structures. General surgeons may face difficulties in identifying and ligating the IMA, particularly in emergencies where time is of the essence. During cardiac surgeries such as coronary artery bypass grafting (CABG), IMA injury can occur during harvesting, and vigilance during closure with stainless steel wires is essential to avoid iatrogenic injury.
Our case series highlights the diversity of clinical scenarios involving IMA injury—from elective surgery to penetrating trauma. In each case, timely identification and surgical management led to favorable outcomes. These cases underscore the need for heightened awareness and swift surgical intervention to prevent morbidity and mortality. Given the scarcity of reported cases, this series adds valuable insights into the diagnosis and management of isolated IMA injuries.
IMA injuries following penetrating or blunt chest trauma, though rare, pose significant risks if not promptly managed. High clinical suspicion, aggressive resuscitation, and timely surgical intervention are key to successful outcomes. Routine imaging should not delay intervention in unstable patients.
Disclosure
The authors declare no conflicts of interest, financial or otherwise.
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