The Use of Transesophageal Echocardiography in Determining the Structural and Functional Impact of Traumatic Intracardiac Foreign Bodies

This is a case of a healthy 15-yr-old woman who presented to the emergency room with a history of worsening chest pain and shortness of breath. The day before her admission, she felt an object hit her in the chest while mowing the lawn. Physical examination revealed a 2-mm entrance wound in the right midaxillary line. Her chest radiograph was significant for a foreign body in the mediastinum without evidence of a pneumothorax. A chest computed tomography (CT) scan demonstrated a metallic object oriented in an anteromedial direction (relative to the entry site) that appeared to extend into the left ventricle (Fig. 1). The transthoracic echocardiogram examination excluded the presence of a pericardial effusion, yet could not provide a precise location of the foreign body within the heart or its functional impact. The patient was taken to the operating room and, after an uneventful anesthetic induction and intubation, a right radial arterial line and right femoral vein cordis introducer were placed. A comprehensive transesophageal echocardiography (TEE) examination was conducted prior to incision.

Figure 1.: Thoracic CT scan at the level of T6–7 showing a highly reflective intracardiac foreign body.

The exam demonstrated normal ventricular and valvular function. The midesophageal bicaval (Fig. 2), midesophageal long axis (Fig. 3), and deep transgastric (TG) long axis (LAX) (Fig. 4) views revealed a linear foreign body with a high degree of reflection that appeared to traverse the atrial and ventricular septums and enter the left ventricular outflow tract (LVOT) (Video clips 1 and 2; please see video clips available at www.anesthesia-analgesia.org). The deep TG LAX view suggested the object might also be in the right ventricle. Thrombi appeared to be attached to a portion of the foreign body located in the right atrium (Fig. 2) and LVOT (Fig. 3; TEE clips). Color Doppler detected small (left-to-right jets) atrial and ventricular septal defects. No evidence of a LVOT obstruction was seen by color Doppler. Based on these findings, the surgeons elected to approach the heart via a median sternotomy. Initial visual inspection of the heart demonstrated no evidence of a foreign body. Subsequent palpation of the posterior aspect of the heart, however, revealed a foreign body entering the right atrium. Following the performance of a right atriotomy, a slightly bent, 12-cm piece of wire was found imbedded in the atrial and ventricular septums. The foreign body could not be seen in the right ventricle. The wire, along with the atrial thrombus, was removed, and suture closures of the atrial and ventricular septal defects were performed. A left atriotomy was then made to remove the thrombus in the LVOT. Although no residual trauma, valvular or ventricular dysfunction were noted by TEE examination after the initial repair, a second thrombus was discovered within the left atrium. This thrombus was subsequently removed after reinstitution of cardiopulmonary bypass. The patient’s postoperative course was unremarkable and she was discharged home on the eighth postoperative day.

Figure 2.: Midesophageal bicaval view showing a right atrial thrombus attached to a foreign body at the atrial septum.

Figure 3.: Midesophageal long-axis view showing the tip of the foreign body in the left ventricular outflow tract with thrombus attached.

Figure 4.: Deep transgastric long-axis view showing the intracardiac foreign body exiting the left ventricular outflow tract.

Intraoperative TEE can play a significant role in the operative management of cardiac foreign bodies. The impact of the examination is probably greatest when patients are too unstable to undergo other imaging studies (CT, etc). Historically, the assessment of the structural damage in urgent cases has been limited to what the surgeon could directly visualize or palpate. Unfortunately, important functional information, such as intracardiac shunts or valvular or ventricular dysfunction, could be easily overlooked. Although published reports comparing CT and TEE (or transthoracic echocardiogram) are limited, a few case reports have described the additional utility of using intraoperative TEE in this setting.^1–3 The largest reported series by Mollod and Felner³ demonstrated that TEE significantly altered the surgical management of chest trauma in all 16 patients who had TEE performed intraoperatively. In a case similar to this report, Heldmann et al. were unable to localize the foreign body with TEE, but they were able to exclude the presence of a pericardial effusion and septal injury.² The case report favors CT over TEE for the localization of intrathoracic foreign bodies, but also indicates TEE is a favorable imaging modality in assessing functional and structural damage, especially in the unstable patient.² The goals of our examination were to confirm the intracardiac location of the foreign object, assess its functional consequence (shunts, or valvular or ventricular dysfunction), and insure the object would not interfere with our cannulation strategy. In our case, the examination allowed us to confirm the object was indeed within the heart, identify atrial and ventricular septal defects, and identify large thrombi in the right atrium and LVOT. These findings were then used to determine the most effective surgical approach.

The use of intraoperative TEE for traumatic intracardiac foreign bodies has several limitations including precise three-dimensional orientation of the object, imaging artifacts, and when its use is contraindicated. Although we felt certain the object was intracardiac-based on the septal defects and synchronized movement of the object with the cardiac cycle, the exact orientation of the foreign body was difficult to discern. For example, the portion of the object that appeared to be within the right ventricular chamber (by the deep TG LAX view) was, in fact, absent upon visual inspection. The two-dimensional limitations of TEE are best overcome by performing a comprehensive examination using multiple views and modalities to fully assess changes in cardiac structure and function. Problems with orientation may also be overcome by centering the object of interest and then rotating the scanning plane 180 degrees around the foreign body. If time permits, CT scanning is considered superior to TEE for identifying object orientation.² Imaging artifacts (side lobes, reverberations, etc.) from highly reflective objects can be minimized by decreasing the transmit power (turning down the gain) or using M-Mode and color flow Doppler to determine whether an object in the field is real. Despite these adjustments, image artifacts caused by strong specular reflectors may persist. In patients who have contraindications to the placement of a TEE probe, the use of intraoperative epicardial echocardiography should be considered.⁴ Epicardial imaging provides excellent resolution because it uses higher frequency probes that are frequently closer to the structure of interest than a TEE probe.⁴ In summary, this case illustrates how intraoperative TEE can be used as an adjunct to surgical decision-making in patients with traumatic intracardiac foreign bodies.

ACKNOWLEDGMENTS

The authors would like to thank our cardiothoracic surgery colleagues Drs. J. Michael Dimaio, M.D. (Associate Professor) and Jose Escobar, M.D. (Senior Resident) for the impressive radiographic images and thoughts regarding how intraoperative TEE helped them plan their surgical approach.