The intra-pericardial rupture of the superior vena cava due to blunt thoracic trauma is a rare and life-threatening situation. It has to be searched for signs of cardiac tamponade; with blunt chest trauma history. We report the case of a superior vena cava laceration caused by a road traffic accident in a 32 year old patient. We focus on the need for urgent thoracic surgical exploration in all patients whose condition is unstable in the setting of blunt chest trauma.

Introduction

Cardiovascular trauma involves a large number of lesions of a variable nature, of which tamponade is the most common complication [1]. A distinction is made between closed trauma which can cause damage to the heart and large vessels, including the chest aorta, and penetrating chest trauma which exposes the risk of cardiac injury [2]. Injuries to the great vessels are frequently associated with severe blunt chest trauma, mostly in high-speed deceleration. Traumatic laceration of the superior vena cava is rare and often fatal.

Keywords: Blunt trauma, Laceration, Tamponade, Superior vena cava

Case Presentation
This is a 32-year-old patient who was the victim of a road accident; a pedestrian struck by a car. The patient presented a thoracic and cranial impact point.
An initial physical exam revealed a confused patient, temperature at 37 °C, unstable hemodynamic state with a heart rate at 110 bpm and blood pressure at 80/05 mmHg. This situation required filling and immediate admission to the operating unit with invasive conditioning and monitoring. The first Trans-thoracic echocardiography (TTE) applied a 10 mm pericardial effusion.
Despite low pericardial effusion levels; the radiologic exploration with a body scan was difficult due to the unstable hemodynamic state. The team has decided on an immediate surgical exploration. The approach was a rescue sternotomy, the opening of the tensed pericardium with the evacuation of 200ml of venous blood with prompt hemodynamic stabilization after blood transfusion.
Surgical inspection revealed the source of hemorrhage as an undiagnosed 2cm-2.5cm laceration of the superior vena cava at the atrio-caval junction with a hematoma of 2cm*1cm over the right atrium. The repair consisted of a simple 5-0 braided suture (Figure 1). No cardiopulmonary bypass was required. An electrocardiography examination revealed no cardiac arrhythmia.

A patch of adventitial hematoma (3cm*2cm) in the wall of the right superior pulmonary vein was also noted and respected with setting up a surgicel (Figure 2A).
Then, adequate hemostasis was achieved and intracardiac drainage was set up. Exploration of the sternum showed several fractures in relation to the 3rd and 5th left ribs (Figure 2B). A frame was set up by two steel wires and the sternum was closed with five X-shaped steel wires.
The patient benefited from a postoperative body scan showing a stage II non-surgical splenic contusion on the advice of the visceral surgery team. The duration of postoperative intubation was 4 hours. The use of positive inotropic drugs was transient. Blood transfusion had been conducted with a hemoglobin level at 8 g/l before transfusion. The stay in intensive care was 24 hours. The duration of postoperative intracardiac drainage was 48 hours. The suites were simple. The patient was independent after 5 days with a follow-up of 48 months.

Discussion
Post-traumatic tamponade is a vital emergency. The diagnosis of tamponade and the decision to surgical exploration remain essentially clinical. Nevertheless, in the wounded who present with trauma penetrating the precordium and which remains hemodynamically stable, echocardiography is the complementary examination of choice in search of a hemopericad. In this context, surgical exploration in search of an underlying heart sore is always warranted [1,2].
The severity of the hemodynamic consequences of pericardial effusion is more related to the speed of its constitution than to its volume [3]. Because of the structure of the pericardium, large amounts of fluid can accumulate gradually before clinical signs appear. On the other hand, rapidly formed effusions (a few minutes to a few hours) exceed the ability of the pericardium to adapt, which does not have time to stretch, and the rapid increase in intra-pericardial pressure compromises the filling of the heart cavities and causes a dramatic drop in cardiac output [4]. Closed chest trauma can lead to damage to the heart and large vessels, and penetrating chest trauma can be a risk of heart damage. In this context, tamponade is a common complication that requires evacuation and surgical exploration in search of an underlying heart sore [5,6]. In some cases, percutaneous pericardiocentesis drainage may relieve the patient while waiting for urgent surgical exploration if one is at a distance from an operating unit [7].
In contrast to the hilar vessels, which are well protected, the superior vena cava is about as exposed as the aorta; but it also has another disadvantage, which is to be a very large vessel with relatively thin walls, which explains the possibility of injury during closed chest trauma.

Traumas to the superior vena cava are, in most cases, of iatrogenic origin and result from the multiplication of central catheterization gestures. Iatrogenic wounds can also complicate iterative sternotomies in cardiac surgery.
Closed traumas of the superior vena cava are rarely isolated, but are part of a severe trauma that combines other vascular and visceral intra-thoracic lesions. Superior vena cava injuries by stabbing or firearms are rarely isolated and often associated with injuries to the brachiocephalic artery and the brachiocephalic venous trunks.
In our case, the clinical picture was worrisome, while the pericardial effusion was of low abundance. It was justified to explore the patient in the operating room, with the discovery of a wound of the superior vena cava that was sutured.

Conclusion
Traumatic laceration of the superior vena cava is rare and often fatal. It is a challenging diagnosis that has to be ruled out in the setting of cardiac tamponade, complicating chest trauma with severe deceleration. Surgical exploration is urgent for the patient’s in unstable condition.

Declarations
Ethical approval and consent to participate

Not applicable.

Consent for publication
Written informed consent was obtained from the patient for publication of this case report and accompanying images.

Availability of data and materials
Data sharing is not applicable to this article as no datasets were generated or analyzed during the current study.

Competing interests
Authors declare they have no competing interests.

Funding
No funding was obtained for this study.

Authors’ contributions
All authors have read and approved the manuscript.

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