The Journey of Harmless Bullet: The Perioperative Care of Penetrating Cardiac Injury.

Traumatic injuries to the heart contribute significantly to trauma are associated with high mortality. Cardiac gunshot wounds (GSW) are considered more lethal compared to other injuries and present several unique challenges to the anesthesia management and perioperative care. We are reporting a rare case of a trauma victim who survived a GSW to the heart. We will discuss the perioperative care of penetrating cardiac injuries, the role of the anesthesia team in resuscitation, safe anesthesia induction, cardiopulmonary bypass management, and the essential role of intraoperative transesophageal echocardiogram imaging.

INTRODUCTION

The sequelae of most penetrating cardiac injuries are death, with 90% of cases arriving considered dead on arrival.[12] This high mortality stems from tamponade or massive hemorrhage.[34] The medical literature recommends immediate surgical intervention for survivors.[3]

Our case represents one of the outliers. A 17-year-old male presented, with a single gunshot wound (GSW) to the left costal margin. On further workup, the bullet injured the spleen and traversed the left diaphragm, crossing through the posterior wall of the left ventricle to lodge in the interventricular septum below the tricuspid valve, without signs of tamponade that occurs in more than 80% of victims.[5] The patient was hemodynamically stable on presentation, and he underwent elective bullet extraction on the next day.

CASE REPORT

A 17-year-old male patient presented to trauma unit with a single GSW to left thoraco-abdomen at the anterior axillary line. On presentation, the patient was fully awake and hemodynamically stable. Primary and secondary surveys ruled out other injuries. Chest X-ray demonstrated a retained missile in the cardiac silhouette and left hemithorax [Figure 1]. A left chest tube was inserted, and an emergent transthoracic echocardiogram showed normal ejection fraction, without pericardial fluid or valvular injury, and the presence of high echogenic material below the tricuspid valve septal leaflets. Computed tomography (CT) of the chest and abdomen showed retained foreign body in the interventricular septum and a splenic injury with active extravasation. The patient remained hemodynamically stable and taken to the operating room for exploratory laparotomy. He underwent splenectomy and repair of a laceration of the left hepatic lobe. Postoperatively, a CT angiogram of the aorta with three-dimensional reconstruction showed the retained bullet in the intraventricular septum [Figure 2]. The preoperative transesophageal echocardiogram (TEE) confirmed the same location of the projectile [Figure 3].

Figure 1

Lateral chest X-ray showing the shadow of retained bullet in the cardiac silhouette

Figure 2

Computed tomography chest three-dimensional reconstruction showing the bullet in the right heart, below the tricuspid valve

Figure 3

Preoperative transesophageal echocardiogram showing the hyperechoic shadow of the bullet below the tricuspid valve, no pericardial effusion noticed

The patient returned to the OR for elective sternotomy and extraction of the intracardiac bullet with cardiopulmonary bypass (CPB). In the OR patient was stable, electrocardiogram (EKG) showed sinus rhythm without atrioventricular-block. General anesthesia (GA) was induced using propofol 2 mg/kg, fentanyl 2 mcg/kg, and rocuronium 1 mg/kg, before proceeding with successful intubation. After confirming the bullet immobility and the location away from pulmonary artery catheter (PAC) route, the PAC was inserted successfully intraoperative TEE showed the bullet location in the intraventricular septum, Doppler flow imaging ruled out ventricular septal defect (VSD) or tricuspid valve regurgitation. The transgastric short axis imaging revealed normal contractility. The pre-CPB period was uneventful. The patient then underwent aortic and bicaval cannulation, and CBP was initiated. Cardiac inspection showed an injury in the posterior wall of the left ventricular (LV) with adherent clot without exit wound [Figure 4]. Right atriotomy, bullet extraction, repair of the bullet cavity, closure of LV posterior wall hole were then performed [Figure 5]. Before weaning from CPB, TEE was repeated to rule out any bullet residuals. Doppler flow was used to rule out new VSD or tricuspid regurgitation, bubble test done to confirm no new intracardiac shunts [Figure 6]. Weaning from the CBP was uneventful. The chest was closed, and the patient was extubated the same day and discharged home 4 days later. He has since followed up several times without any sequelae from his injury.

Figure 4

The entry wound in the posterior wall of the left ventricular

Figure 5

The atriotomy and the bullet extraction

Figure 6

The postbypass transesophageal echocardiogram - the agitated saline study. Notice the entrapment of air microbubbles in the right heart. No signs of new shunt

DISCUSSION

Penetrating cardiac injuries are rare, and cardiac GSWs are associated with the highest mortality rate among all traumatic injuries.[67] Conventional wisdom recommends the necessity of immediate surgical intervention. Our case report highlights the importance of triaging these victims into two groups, the clinically or imaging unstable and the stable patients. In our case, the extensive preoperative workup and the elective surgical intervention led to a favorable outcome.

Patients presenting with hemorrhagic shock, or impending collapse revealed by occult shock[8] or the presence of tamponade benefit from immediate surgical exploration. Resuscitation and emergency department thoracotomy (EDT) have a limited role.[9] EDT is indicated only in patients without vitals. Expedited transfer to OR with midline sternotomy allows extensive exploration of the heart, major vessels, and bilateral pleural spaces[13] and prompt repair with or without CPB.

Patients with normal physiological status, on admission, benefit from a comprehensive preoperative workup. This approach allows precise localization of the missiles, diagnosis of associated injuries, and differentiate between high-risk and low-risk retained missiles [Table 1].[10]

Table 1

Retained missiles management

Based on the workup results, patients are assigned for early elective, delayed retrieval, or no intervention.[1112] Location also determines the need for CPB. Nonoperative retrieval of the bullet can be utilized in certain situations.[12] In our case, early elective retrieval of the bullet is indicated because of the proximity to the tricuspid valve and interventricular septum and the conduction system.

Anesthesia management for cardiac GSW injuries differs widely according to the severity of the clinical condition. The general principles of anesthesia management include maintaining hemodynamic stability on induction, management of CPB, and TEE imaging.

Preserving hemodynamic stability requires thorough preoperative evaluation and planning. Symptoms and signs to look for are signs of hypoperfusion, abnormal cardiac filling, abnormal vital signs such as pulsus paradoxus, a shock index >0.9,[8] EKG for pulsus alternans, and the perioperative cardiac imaging. GA is always required for cardiac injury repair. Preinduction arterial line insertion and availability of massive transfusion of blood products, and defibrillator are essential for success.[1314] There are two options for anesthesia induction, either inhalation induction while maintaining spontaneous breathing, or intravenous induction with agents with minimal cardiac depression such as ketamine.[15] The hemodynamic goal is to maintain preload, high sinus rate, and after load. Some authors recommend against volume overload as it may increase the risk of bleeding.[1617] A physiologically intact patient can undergo regular induction. Our patient was hemodynamically stable, and anesthesia induction and operative management were uneventful.

CBP indications are presented in [Table 2].

Table 2

Cardiopulmonary bypass indication in penetrating cardiac injury

In our case, CPB was indicated because of the intracavitary location of the bullet and proximity to the tricuspid valve.

TEE is essential in all three phases of perioperative care.[1819] Preoperative TEE is very sensitive to detect tamponade, shunts, valve injury, or coronary artery injuries and reveals the precise location of the bullet. Intraoperatively in the pre-CPB period, TEE is indicated to guide cannulation, monitor volume status, myocardial contractility, and changes in location of mobile bullets. Post-CPB, TEE is indicated to rule out any residual missiles, iatrogenic shunts, or new valve injury.[181920] In our case, we used color Doppler flow to check the valve status and agitated saline to rule out new shunts. It is imperative to rule out any concomitant esophageal injury before TEE probe insertion, and this highlights the importance of extensive preoperative workup in stable patients.[21]

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Conflicts of interest

There are no conflicts of interest.