Air Rifle Injury: Rare Bullet Lodgement in the Right Ventricle and Successful Surgical Removal

Introduction

Air rifles, well known for their use in sports and entertainment, use compressed air to propel a projectile. However, inappropriate use of air rifles can result in complex, violent, and traumatic injury that is commonly encountered in clinical practice. These injuries are devastating injuries that are associated with high morbidity and mortality, especially in the chest area. This region contains several vital organs, including the heart, and lungs, the spinal cord, vertebrae, and several major blood vessels, such as the aorta and vena cava. Therefore, this area is particularly susceptible to damage from thoracic trauma. Currently, about 20 000 air rifle-related injuries occur annually in the United States alone [1,2]. In general, injuries caused by air rifles are less common than those caused by firearms. Pellets fired from an air rifle do not undergo rotational movement, and therefore, do not produce a temporary cavity, typically observed in gunshot injuries [3]. However, air rifles can generate projectile velocities ranging from 100 to 230 m/s [4]. The degree of air rifle injury will depend on the type and velocity of the pellet, the extent of subsequent anatomical damage, shooting distance, angle of impact, passage through obstructions, projectile stability, and body area impacted [5,6]. Furthermore, the entrance profile, trajectory through the body, and biological characteristics of the affected tissues also contribute to the extent of injury [7]. Typically, dyspnea will manifest initially, followed by complications, such as hemorrhage, infection, hemothorax, cardiac tamponade, neurological dysfunction, and vertebral fractures. In such situations, an interdisciplinary surgical approach is required. In rare instances, the projectile can remain within the chest region, making the pellet’s trajectory and final location uncertain [8,9]. To the best of our knowledge, there have been very few reports in the literature documenting a chest wall air rifle injury with the projectile remaining in the intracardiac space without an exit wound. Thus, in this paper, we present an extraordinary case of a projectile that penetrated the patient’s right chest wall and reached the right ventricle of the heart, without exiting the body. This case report is presented in accordance with the updated CARE guideline for case reports [10].

Case Report

INVESTIGATIONS:

To assess the overall condition of the patient’s thorax, a chest X-ray was performed, revealing the presence of hemothorax in the right hemithorax and right pulmonary contusion (Figure 2). Following up on these findings, a #28 Fr chest tube was inserted into the right hemithorax at the level of the fifth rib on the same day. Initial drainage of 500 cc of hemorrhagic fluid was obtained, which demonstrated undulation and forceful bubbling, indicating ongoing bleeding. Based on the findings from the chest X-ray, transthoracic echocardiography (TTE) was conducted to evaluate the condition of the heart and to determine whether the projectile was located the intra- or extracardiac region. The TTE revealed a hyperechoic mass on the septum of the right ventricle, measuring 0.6×0.6 cm, along with mild pericardial effusion and pleural effusion (Figure 3). Subsequently, further imaging was performed with a non-contrast computed tomography (CT) scan as part of the preoperative preparation for projectile removal, providing precise information regarding projectile location, trajectory, and exact size. The pellet, approximately 0.5×0.5×0.78 cm in size, was visualized lodged in the posterior right ventricle, 4.05 cm from the right ventricle entry port. It was positioned 4.4 cm posterior to the sternum, 3.9 cm anterior to the ninth thoracic vertebra, and 6.89 cm from the left ventricle. The wound track extended from the lateral to medial side of the right middle lung lobe, with a distance of 7.68 cm from the entry port in the 5–6 intercostal space on the lateral right thoracic wall to the right heart border at the level of the ninth thoracic vertebra (Figure 4).

DIFFERENTIAL DIAGNOSIS:

Based on the findings from the physical examination and diagnostic investigations, pneumothorax, fracture of the costae, and subcutis emphysema were ruled out. Chest X-ray demonstrated that the trajectory of the projectile caused a concomitant injury to the right lung, accompanied by pericardial effusion and right-sided hemothorax. CT and echocardiography revealed a projectile retained within the intracardiac right ventricle. Therefore, a water-seal drainage system was placed.

TREATMENT:

Based on the findings from the CT scan, the projectile was identified as being lodged in the posterior region of the right ventricle, located 0.8 cm from the tricuspid annulus. Consequently, a cardiopulmonary bypass with beating heart surgery was performed. Suturing of the entry site on the right ventricular wall was performed using pledgeted 4-0 Prolene. The cardiac size and contractility were found to be within normal limits, with minimal pericardial effusion. A right atrial incision was made, followed by exploration of the posterior right ventricle myocardium through the tricuspid valve (Figure 5A). An intact 3×3×5-mm air gun pellet was observed in the posterior right ventricle wall and subsequently extracted (Figure 5B, 5C). No lung lacerations were noted during the thoracic cavity evaluation, but a hematoma clot was present. The pellet was successfully removed from the heart, and 100 cc of hematoma clot was evacuated (Figure 5D). After cross-clamping, the patient developed ventricular fibrillation, which persisted despite the administration of 100 mg of lidocaine. Cardioversion was performed at 10 J, restoring sinus rhythm. The patient underwent cardiopulmonary bypass for 72 min and aortic cross-clamping for 21 min. Postoperatively, a transesophageal echocardiogram was performed, which showed no evidence of fistulization in the right ventricle wall.

OUTCOME AND FOLLOW-UP:

After regaining consciousness, the patient experienced tonic-clonic seizure lasting for 30 s in the Intensive Care Unit, which were treated with midazolam and propofol, resulting in the cessation of the seizures and resedation. Laboratory results on the same day revealed anemia, respiratory acidosis, leukocytosis without fever, elevated SGOT, and slight hypoalbuminemia (albumin 3.39 g/dL). During the postoperative period, the patient received prophylactic ceftriaxone, intravenous phenytoin injection, vitamin B6, and folic acid via a nasogastric tube, as well as oral administration of aspirin, ibuprofen, and omeprazole. Hemodynamic support therapy was continued, and the chest drain was maintained with active suction. On the third postoperative day, the patient’s clinical condition improved, and he was able to sit independently, although he continued to experience dizziness when transitioning from sitting to lying down and vice versa. By the fourth postoperative day, the patient was free of concerns, and all physical examinations were within normal limits. As a result, the decision was made to discharge the patient. Afterward, the patient underwent routine outpatient follow-ups once a week and underwent an electroencephalography examination 1 month after discharge, with normal results. The patient did not report any concerns during the 2-month outpatient follow-up period.

Discussion

The case presents the clinical symptoms as a result of an air rifle injury. Unusual presentations of pellet trajectories in air rifle injuries can pose significant challenges in surgical management and medico-legal diagnosis [8,11–13]. Therefore, identifying the location of the projectile is crucial for the following reasons: (1) direct injury to coronary vessels can occur, potentially leading to ST-segment elevation myocardial infarction (STEMI); (2) cardiac injury can lead to abnormalities in the conduction system, including heart blocks, and arrhythmias; (3) structural cardiac damage can lead to valvular or sub-valvular injury, fistulas, aneurysms, or ventricular free-wall rupture; (4) pericardial trauma, including effusion, laceration, and hemopericardium, can arise; and (5) projectiles, such as pellets, can become embedded within the intracardiac chambers, posing a risk of distal embolization [14].

Given that the patient sustained the air rifle injury while repairing an air rifle, it indicates a very close range of firing, which significantly increases the potential for fatality. Such injuries typically involve high-energy transfer, with the projectile being potentially lethal at distances up to 200 m [15]. Due to the mechanism of air rifle pellets, which lack rotational movement, the kinetic energy generated is insufficient to penetrate tissue completely [16]. As a result, as observed in this case, the projectile can become embedded within the tissue, without the presence of an exit wound. In this case, a chest X-ray was performed to identify the overall condition of the thorax. Nevertheless, determining the pellet’s trajectory and precise location is difficult with chest X-ray alone. Consequently, findings were further clarified using TTE and a non-contrast CT scan. These imaging techniques provided the best visualization of the pellet’s location and size, and the condition of surrounding tissues. This approach is essential, as CT scanning is the modality of choice for detecting hemorrhage, air, foreign bodies, bone fragments, hemothorax, vascular injury, and musculoskeletal lesions [17]. Since the bullet was not found to be fully embedded in the ventricular wall, and given the patient’s stable hemodynamic and cardiac condition, bullet extraction was deemed necessary due to the high risk associated with the presence of a foreign object within the heart.

The right ventricle is typically more frequently damaged than other heart chambers, which attributed to its more anterior location in the thorax. However, in this case, since the projectile entered from the right hemithorax, the right ventricle was also the area closest to the pellet’s entry point. Although this area of the chest is highly vascularized and contains several vital organs, the patient was fortunate to not sustain any life-threatening injuries.

The management of patients with heart air rifle injury is primarily determined by the patient’s hemodynamic condition. In this case, the patient’s hemodynamic condition and vital signs were within normal limits, allowing an emergency exploratory surgery. It is imperative to comprehend the pathophysiology and mechanisms underlying air rifle-related wounds, in conjunction with the implementation of prompt interventions, to avert potential complications. This is of particular significance in cases involving surgical interventions, which carry a substantial risk of injury to surrounding structures, due to the potential for iatrogenic complications [18]. Few previous studies have reported cases of air rifle injuries involving the cardiac region [19–23]. In most cases, surgical extraction of the projectile was performed due to the high risk of migration, embolism, or bleeding in other parts of the body. However, the decision not to extract the projectile can be considered in cases of reduced biventricular function or when the projectile is fully embedded within the tissue.

Conclusions

Air rifle-related trauma presents significant challenges for patients, clinicians, and families, alike. There is a critical need for increased awareness of cardiac penetrating wounds, a thorough understanding of projectile trajectory, and the recognition of unpredictable clinical signs. A multidisciplinary approach, incorporating both the patient and family involvement, is essential to achieving favorable outcomes and ensuring long-term clinical monitoring and follow-up.