Cardiac Tamponade

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  This condition results from fluid accumulation under pressure into the pericardial space, found in 2% of penetrating injuries to the chest and abdomen. Up to 80% of stab wounds to the heart result in tamponade. GSWs cause larger pericardial defects and less likely cause tamponade.

  
  
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  Blood in the pericardial cavity may form a hematoma. Fluid results in elevated pericardial pressures, decreasing RV and LV filling. HR increases to improve RA and RV filling. Even amounts less than 100 mL may result in elevated pericardial pressures.^{9, 11, 19, 20}

  
  
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  RV distension pushes the septum into the LV, decreasing LV filling and cardiac output. This leads to shock and death.⁹

  
  
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  US is essential in evaluation, as tamponade is difficult to diagnose in trauma patients. Elevated HR and vascular resistance can partially compensate for tamponade, with tachycardia often the first indication. Beck’s triad (muffled heart sounds, hypotension, and JVD) is found in less than 10% of patients, and pulsus paradoxus is also not reliable.¹⁰ Narrowed pulse pressure is frequent, and hypotension is an early sign of decompensation.

Cardiac Missile

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  This may result from direct injury or embolization. If retained from another site, patients are often stable and observed.

  
  
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  Treatment of these missiles is dependent on size, mechanism, shape, and location. If symptoms or hemodynamic instability are present, patients should go to the OR for removal of the missile. Others that require removal include those within coronary vessels or those that have embolized.^26–28

Iatrogenic Injury

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  Pericardiocentesis, chest tube placement, coronary catheterization, and electrophysiological and valvular procedures may result in injury.²⁹

Cardiac Rupture

This is the most severe form of blunt cardiac injury. The right side is at highest risk for rupture, and patients often die at the scene.^{2, 10, 30} Patients who survive may display a murmur. US may immediately diagnose this condition, and if discovered, the patient requires thoracotomy.

Coronary Vessel Injury/MI

Injury to cardiac vessels is rare. The most common injured vessel is the left anterior descending artery. Coronary vessel dissection and coronary artery disease most often occur in the first 7 days.^31–34 Patients most commonly present with chest pain. Patients require percutaneous intervention, though anticoagulation requires consultation with cardiology and cardiothoracic surgery due to risk of hemorrhage.^{2, 9, 10}

Injury to the Valves, Papillary Muscles, Chordae Tendinae, and Septum

Valvular damage occurs in 10% of cardiac trauma cases, though it usually occurs with other injuries. The aortic valve is the most common valve injured, which may cause aortic regurgitation and pulmonary edema. Injury to the cardiac septum may occur but is rare.^{31, 32, 35} Any new murmur or pulmonary edema in a patient with chest trauma requires US and resuscitation with surgical consultation. Small injuries may heal on their own, but this is not common.

Pericardial Injury

Defects in the pericardium may result from blunt impact, often parallel to the phrenic nerve on the left side of the pericardium.^{2, 8, 9} These defects are often missed, and they may not be associated with symptoms. If herniation occurs, cardiac conduction is often interrupted. Exam can demonstrate pericardial rub, though this is not common. US or CT may demonstrate injury, which requires surgical repair.^{2, 8–10}

Cardiac Dysfunction

The frequency of this injury is unknown and difficult to determine in the multisystem trauma patient. Patients usually present with chest pain, and patients may also have pulmonary vascular injury, decreasing LV preload, and in combination with RV output, reduced cardiac output may occur. Damage to the myocardial tissue and conduction system can also further harm cardiac output. Monitoring is needed for dysrhythmias, which include tachycardia, bundle branch block, high degree blocks, supraventricular tachycardia, ventricular fibrillation, and premature ventricular contractions, which can occur up to 48 hours after blunt injury.^{2, 3, 13, 35}

Commotio Cordis

This injury consists of sudden death associated with blunt injury to the anterior chest wall and is the most common cause of death in young athletes (baseball and lacrosse).^{8–10, 36} Commotio cordis injury is usually due to a low impact blow that strikes the heart and results in ventricular fibrillation, occurring 10–30 ms before the peak of the T wave. Cardiac anatomy is usually normal. Survival rate is less than 15%. If suspected, immediate compressions and defibrillation are required.^{36, 37}

Multisystem Trauma

Blunt cardiac injury is associated with many other injuries, often occurring in the setting of multisystem trauma (Table 14.1).^{2, 9}

Electrocardiogram (ECG)

An ECG is needed when able. A normal ECG alone is not enough to exclude significant injury, which may miss up to 20% of cases.^{13, 16, 42, 43} A significant dysrhythmia can occur within 48 hours of the initial injury (Table 14.2).

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  The ECG is more sensitive for left sided rather than right sided injuries. One of the most common findings is persistent tachycardia, which is nonspecific with a variety of etiologies. ST changes, especially elevation, may suggest MI.^{9, 12, 16, 44}

  
  
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  If initial ECG is normal but concern for blunt injury is present, 4–6 hours of continuous cardiac monitoring is needed. If monitoring is normal with no new symptoms, patients may be appropriate for discharge. Any ECG abnormality requires further evaluation.^{9, 12}

  
  
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  Pericardial effusion if large may demonstrate low voltage and tachycardia. Electrical alternans, though considered the classic finding for cardiac tamponade, is not 100% sensitive for tamponade.^{2, 9}

Laboratory Assessment with Cardiac Biomarkers

A great deal of controversy is present concerning biomarkers.

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  Creatine kinase (CK)-MB elevates with injuries of other systems such as the liver or intestines. Also, isolated elevation of CK-MB does not predict mortality, and it is not recommended.

  
  
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  Troponin is specific for myocardial injury, though not the etiology.^{9, 45–47} Troponin sensitivity for cardiac contusion ranges from 12–23%, with specificity over 97% in the setting of trauma.^45–48 Causes of shock other than primary cardiac etiology may also result in troponin elevation.

  
  
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  Troponin elevation is correlated with decreased ejection fraction, dysrhythmias, and LV dysfunction.^{47, 48}

  
  
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  The use of troponin and ECG may improve risk stratification, as negative ECG and troponin are associated with extremely low risk of blunt cardiac injury. Abnormal ECG warrants troponin testing. Any abnormality in ECG and troponin testing strongly suggests blunt cardiac injury.^47–51

Ultrasound

The FAST exam requires cardiac images via the subxiphoid or parasternal long axis view. FAST exam allows evaluation of gross cardiac function and the presence of cardiac effusion (Figure 14.4). US displays a sensitivity and specificity over 99% for detection of pericardial effusion.^{2, 3, 52–56}

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  Patients with abnormal cardiac troponin, dysrhythmia, and concern for blunt cardiac injury require US. Transthoracic echocardiogram (TTE) may demonstrate dissection.^{9, 57}

Figure 14.4 Ultrasound with evidence of pericardial tamponade. Solid white arrow is RV, while clear arrow is pericardial effusion

(image courtesy of James Heilman, MD, reproduced here under CC BY-SA 3.0 license https://creativecommons.org/licenses/by-sa/3.0/)

Transesophageal Echocardiography (TEE)

TEE is portable and fast, with immediate bedside results. This is promising; however, few emergency physicians are trained in this modality. This modality is also useful in the potentially unstable patient.⁵⁸ TEE can detect aortic lesions (including full rupture and intimal defects). However, it is contraindicated in patients with potential airway issues (if not already intubated) or cervical spine injury.^54–56

Chest X-ray

This imaging modality is not sensitive or specific for injury. Cardiomegaly is rare in acute pericardial effusion and tamponade. Widened mediastinum may suggest aortic dissection, with width greater than 8 cm (Figure 14.5, Table 14.3).^{2, 3, 59–62} Other findings include esophageal deviation more than 1 cm to the right of the spine at the T4 level.^{62, 63} A normal chest X-ray does not rule out aortic injury.

Figure 14.5 Blunt thoracic aortic injury. Chest x-ray shows a widened mediastinum and deviation of the trachea to the right (left). CT image confirms thoracic aortic injury (right)

(reproduced with permission from Color Atlas of Emergency Trauma, Second Edition)

Computed Tomography (CT)

CT of the chest with contrast is the modality of choice for penetrating and blunt chest trauma (Figure 14.6, Table 14.4). Multidetector scanners display sensitivity and specificity approaching 100% for vascular and lung injuries. In penetrating injury, evaluation of injury tract and vascular involvement is essential. However, in blunt cardiac injury, CT may detect wall motion abnormalities.^23–25 CT with IV contrast is definitive for great vessel injury, with defects appearing as irregular vascular contours, vessel lumen abnormalities, dissection, aneurysm/pseudoaneurysm, and acute bleeding. CT also depicts the tract of injury, including knives and missiles.^{2, 9, 23–25}

(reproduced with permission from Color Atlas of Emergency Trauma, Second Edition)

Figure 14.6 (A) CT angiography with 3-D reconstruction shows a contained aortic rupture (left). Endoluminal view of the aortic pseudoaneurysm (right). (B) CT images of a blunt thoracic aortic injury with leak. This patient needs an emergency operation because of the risk of imminent free rupture. (C) Aortogram of traumatic aortic pseudoaneurysm, (left) treated with stent-graft deployment (right). Note the occlusion of the left subclavian artery by the device. (D–F) CT scan showing a rupture of the thoracic aorta (D). CT scan appearance of the deployed stent graft with occlusion of the rupture site (E, F)

MRI

This imaging modality is not available in all institutions, and the time required is usually prohibitive. It provides similar information as CT.^{2, 9}

Penetrating Trauma

ED Thoracotomy (EDT)

Unstable patients with cardiac activity and penetrating cardiac injury require the OR emergently. Patients who lose pulses in the ED with penetrating or blunt trauma are eligible for EDT (Table 14.5).^{2, 3, 9, 66–68} Others include patients with penetrating thoracic trauma and hemodynamic instability, despite fluid resuscitation or if pulseless less than 15 minutes.^69–72

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  EDT is not recommended if asystole is present with no pericardial effusion, pulselessness >15 minutes, other massive nonsurvivable injuries, no pulse in the field, and blunt cardiac arrest.^{2, 9}

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  Procedure (Figure 14.7): Left anterolateral thoracotomy is the classic procedure. The left sided approach allows exposure of the phrenic nerve, aorta, and left side of the chest cavity.^{2, 3, 66–72}

  
  
  
  
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    The patient should be intubated with NG/OG placed before the procedure. The left 4th or 5th intercostal space should be identified (the intercostal space below the male’s nipple or inframammary fold in a woman), with primary incision at this location.

    
    
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    The site should be quickly sterilized and incised with one broad stroke through all layers to the intercostal muscles down to the posterior axillary line. These muscles should be cut with Mayo scissors.

    
    
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    A Finochietto retractor is then placed within the chest, with the crank near the bed. The retractor is opened to expose the left chest cavity.

    
    
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    Control any hemorrhage with direct pressure. Move the lung to expose the pericardium.

    
    
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    Signs of cardiac injury include distended, discolored, and tense pericardial sac. The pericardium should be incised anterior to the phrenic nerve to allow inspection of the heart for injury.

    
    
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    Digital occlusion of the wound can be the first maneuver, but a finger should never be inserted into the heart, which can extend the injury.

    
    
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    Staples via skin stapler is fast and effective. Suturing is also effective but difficult due to cardiac activity. A Foley catheter can be placed within a wound, the balloon inflated and gentle retraction placed on the catheter, and then the catheter sutured into place.

    
    
  • 
    

    When suturing, horizontal mattress sutures or interrupted sutures are effective, and pledgets may reinforce the suture and prevent further damage to the heart.

    
    
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    If cardiac function is absent, internal cardiac massage should be performed. Care should be taken to avoid coronary vessel damage.

    
    
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    If no left-sided injury is discovered, the thoracotomy should be extended to the right with a clam shell across the sternum and down the right. This may assist with improved exposure to the right side of the heart, as well as the right lung.

    
    
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    The descending aorta can be cross-clamped.

  
  
  
  
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  If the patient regains pulses or vital signs improve, the patient requires the OR. Survival rate approaches 80% for knife wounds and 40% for gunshot wounds.

Table 14.5 Trauma association guidelines^{71, 72}

Eastern Association for the Surgery of Trauma

EDT is best for patients with penetrating cardiac trauma who arrive to a trauma center with short scene and transport time and witnessed or objectively physiologic signs of life. EDT should be performed in patients with penetrating noncardiac thoracic injuries, but with low survival rates. EDT may be used to establish the diagnosis of whether the injury is cardiac or noncardiac. EDT should be rarely performed in patients with cardiac arrest due to blunt trauma with low survival rate and poor neurologic outcomes. EDT should be limited to patients who arrive with vital signs at the trauma center and experience cardiac arrest that is witnessed. EDT should be performed in patients with exsanguinating abdominal vascular injuries, though with low survival.

Western Trauma Association

Patients undergoing CPR on arrival to the hospital can be stratified based on injury and transport time. Indications include: Blunt trauma patients with less than 10 minutes of prehospital CPR, Penetrating torso patients with less than 15 minutes of CPR, patients with penetrating trauma to the neck/extremity with less than 5 minutes of CPR, patients in profound refractory shock. Following EDT, evaluate the patient’s intrinsic cardiac activity. Patients in asystole and no cardiac tamponade should be declared dead.

Figure 14.7 Emergency room resuscitative thoracotomy for injury to the heart. (A) Illustration of the incision for a resuscitative emergency department left anterolateral thoracotomy. (B) Photographs showing incisions for resuscitative thoracotomy, in a female and a male patient. (C, D) Illustration and photo of the pericardium at thoracotomy. The phrenic nerve is seen on the lateral aspect of the pericardium. The pericardium should be opened above the nerve (C). The pericardium is opened and the heart exposed (D). (E) Illustration and intraoperative photograph showing the use of a Foley catheter for temporary bleeding control from a cardiac wound. (F) Photograph of a cross-clamping of the thoracic aorta. The clamp should be applied about 3–4 cm above the diaphragm. (G) Photograph of internal cardiac defibrillation during emergency room resuscitative thoracotomy

(reproduced with permission from Color Atlas of Emergency Trauma, Second Edition, illustrations at A, C and E by Alexis Demetriades)

A second approach for EDT, perhaps faster with greater exposure, is to perform bilateral finger thoracostomies and then connect these incisions, completing a clamshell.^73–75