Historical Perspective

Cardiac chamber rupture and myocardial contusion were first reported after autopsy findings as early as 1679 by Borch¹ and in 1764 by Akenside.² In 1868, 76 cases reported by Fischer³ described 7 myocardial contusions and 69 traumatic ruptures. Experimental animal work and clinical autopsies by Beck and Bright⁴ demonstrated that severe forces are responsible for an entire range of cardiac trauma, whereas enormous force is required to rupture the heart. Recovery is the general rule, and rupture is the exception. In 1958, Parmley⁵ performed a hallmark study reviewing a large series of autopsy cases at the Armed Forces Institute of Pathology and demonstrated that blunt traumatic heart injury had a 0.1% incidence, with the majority being isolated chamber ruptures (right then left ventricle, followed by right and left atria in decreasing order of occurrence) and some associated with combined aortic ruptures. Blunt cardiac injury is the most commonly seen form of cardiac trauma and rarely results in death. Cardiac chamber or aortic rupture is usually fatal.

Mechanism, Pathophysiology, and Incidence

Blunt cardiac and vascular injuries may be caused by any transfer of kinetic energy, including blasts, deceleration, falls from heights, and direct crushing forces through the sternum or rib cage. These can cause compression of the heart against the vertebral column as well as traction and torsion. A resultant sudden elevated blood pressure from compression of the chest may injure the cardiac valves, cause a tear in the ventricular wall or septum, or result in chamber rupture.

These forces result in a continuous spectrum of cardiac injury ranging from simple contusion to fatal cardiac chamber rupture, including commotio cordis, described as sudden cardiac arrest from a sternal blow.⁶ Myocardial contusion, characterized by patchy areas of muscle necrosis and hemorrhagic infiltrate, may also impair ventricular contraction and lead to arrhythmia.

The true incidence of blunt cardiac injury remains expectedly difficult to measure because the majority of patients with blunt trauma recover spontaneously. Autopsy cases of fatal cardiac chamber rupture do not account for the majority of the blunt trauma cases.

Clinical Presentation and Diagnosis

The rupture of a cardiac chamber or blunt injury to a coronary artery, a major intrapericardial vein, or the ascending aorta is usually fatal because of acute pericardial tamponade. The few patients who survive do so only because of tears in a cavity under low pressure.^7–9 Blunt cardiac injury (myocardial contusion) induces cardiac failure and arrhythmia that improves with time.^10,11 Injury to a coronary artery can lead to immediate or delayed myocardial infarction with spasm or dissection of the arterial wall.¹² Valvular tears resulting in aortic or mitral insufficiency can develop into cardiac failure, ranging from a few hours to a few weeks, whereas tricuspid insufficiency may appear only after several years.^13–15

Paramount to an accurate diagnosis is information derived from the history and physical findings. A history or findings of pain and tenderness over the anterior chest wall (which may be indistinguishable from a classic myocardial infarction), evidence of chest wall contusion, ecchymosis, anterior rib fractures, and flail chest are all associated with cardiac injury.¹⁶ Many patients, however, do not present with characteristic history, signs, or symptoms.^11,17,18 Complex arrhythmias, subtle findings of a precordial thrill, or a murmur may also be noted on physical examination. Cardiac injury can also be manifested by hemodynamic instability marked by refractory hypotension and elevated venous and cardiogenic shock. External jugular vein distention may be absent in cases of blood loss.

Spectrum of Blunt Cardiac Injury: Assessment and Management

Cardiac Chamber Rupture

Cardiac chamber rupture is relatively uncommon^7,37–39; only a small percentage of patients survive to reach the hospital. Several mechanisms for blunt cardiac rupture have been postulated⁷: direct precordial impacts; compression of the heart between the sternum and vertebral body; transmission of pressure through the abdomen into the venous return, rupturing particularly the atria; acceleration-deceleration injuries, leading to tears of the heart at the attachment sites to the great vessels; blast effects; and concussive blows thought to be fatal secondary to the production of malignant arrhythmias. Patients usually present with persistent hypotension with evidence of pericardial tamponade. Diagnosis of widened mediastinum on chest radiography or evidence of pericardial fluid on sonographic examination requires prompt intervention. Once popular as an initial diagnostic modality, subxiphoid window (Fig. 75-1) should be avoided, as it consumes valuable time, results in a secondary thoracic incision, and exposes a ruptured heart from a tiny abdominal incision. For patients who present with cardiopulmonary arrest, an emergency department thoracotomy may be their only chance, although survival statistics are dismal.

Figure 75–1 The technique for performing subxiphoid pericardial window, a technique no longer recommended. After removal of the xiphoid, a suture is placed to distract the pericardium, which is opened to evacuate fluid and to examine the pericardial cavity.

Conclusion

Blunt cardiac injury should always be suspected from a detailed history and physical examination, prompting further diagnostic testing, if it is clinically indicated, with electrocardiographic monitoring and serial enzyme measurements. Sonographic examination can elucidate pericardial fluid or cardiac or valvular dysfunction that may require prompt surgical intervention.

Historical Perspective

Historically, an injury to the heart has been considered a death sentence. As early as the Iliad,⁴² Sarpedon died of an impalement to the heart by a lance. Hippocrates,⁴³ Aristotle,⁴⁴ Galen,⁴⁵ Fabricius,⁴⁶ and Boerhaave⁴⁷ described such wounds to the heart as futile. Morgagni,⁴⁸ in 1761, described the compressive effects of blood on the heart with hemopericardium. Larrey⁴⁹ was credited for pioneering the technique of pericardial window to release pericardial tamponade. Ludwig Rehn⁵⁰ performed the first successful repair of a cardiac injury in 1896 in Frankfurt.

Duval⁵¹ first described the median sternotomy incision; Spangaro,⁵² in 1906, first described the left anterolateral thoracotomy incision. Beck, in 1926, described the triad physiology of cardiac tamponade and later described the repair technique of placing mattress sutures under the coronary vessels to spare ligation.^53,54

Harken,⁵⁵ in 1946, described the removal of foreign bodies adjacent to the heart and great vessels. Beall^56–59 first described emergency department thoracotomy and along with Cooley⁵⁸ reported the potential benefits of cardiopulmonary bypass in the management of selected intracardiac injuries. Mattox^60–62 further refined emergency department thoracotomy and cardiorrhaphy including emergency cardiopulmonary bypass.

Mechanism, Pathophysiology, and Incidence

In the civilian arena, penetrating cardiac injuries are primarily the result of gunshot and stab wounds. A subset of stab wounds consists of penetrating cardiac wounds from iatrogenic needles, trocars, and catheters.

In the military arena, most soldiers do not survive the high-velocity automatic rifle injuries seen in battle. The majority of these patients have sustained injuries from fragments of grenades or shrapnel. Rich⁶³ described 96 patients with penetrating injuries arriving at treatment facilities based on data from the Vietnam conflict.

Penetrating cardiac injuries are uncommon and are most often described in busy urban trauma centers. However, even iatrogenic penetrating cardiac injury can be seen in any clinic or hospital, especially after pericardiocentesis. The true incidence is difficult to ascertain because the numbers fluctuate in conjunction with the incidence of violent crimes involving firearms or penetrating objects. Feliciano⁶⁴ described a 1-year experience of 48 cardiac injuries at Ben Taub Hospital in Houston. Mattox,⁶⁵ in 1989, described a 30-year experience from the same institution, reporting 539 cardiac injuries. Asensio^66,67 reported a total of 165 cardiac injuries within a 3-year period at Los Angeles County–University of Southern California Medical Center. In 2000, Tyburski⁶⁸ reported an 18-year experience of 302 patients with penetrating heart injuries undergoing emergency thoracotomy.

Clinical Presentation and Diagnosis

Most cardiac injuries caused by stab wounds are logically based on the trajectory of the insult. This is not so with gunshot wounds, which can injure the heart from precordial and extra-precordial entrance sites.⁶⁹ Mattox⁷⁰ described 26% associated cardiac injuries in 82 patients presenting with combined thoracoabdominal injuries; Asensio⁷¹ reported 44% incidence of associated penetrating cardiac injuries in his series of 73 patients who sustained thoracoabdominal injuries.

Frank penetrating injuries to the cardiac chambers may lead to acute cardiac tamponade and death; similarly, hemorrhage through the lacerated pericardium into the hemithorax can lead to death as well. Patients surviving such injuries have intact pericardium that prevents fatal exsanguinating hemorrhage and allows them to reach the trauma center alive but with varying degrees of hemodynamic instability^63,66 secondary to pericardial tamponade. Interestingly, Beck’s triad (muffled heart sounds, jugular venous distention, and hypotension) and Kussmaul’s sign (jugular venous distention with inspiration) are present in only 10% of patients⁶⁹ with pericardial tamponade.

Moreno,⁷² in a retrospective study looking at 100 patients with penetrating cardiac injuries, reported higher survival (77% versus 11%) in patients who present with pericardial tamponade, and right-sided chamber injuries confer a higher survival (79%) versus left-sided chamber injuries (28% survival).

Potential cardiac injuries should be highly suspected in patients sustaining penetrating injuries, whether by stab wounds or gunshot wounds. Chest radiography is performed on hemodynamically stable patients, and a widened mediastinum signifies the need for further workup. Sonography can determine the presence of pericardial fluid, and this is supported by a thorough physical examination, which may reveal Beck’s triad or Kussmaul’s sign. Evidence of direct trajectory to the heart usually leads to emergent anterolateral thoracotomy, should the patient acutely decompensate clinically.

Subxiphoid Pericardial Window

The reliability of this technique (see Fig. 75-1) versus pericardiocentesis (Fig. 75-2) has been controversial in the evaluation and treatment of penetrating cardiac injury.^73–78 These techniques might demonstrate hemopericardium when two-dimensional echocardiography (applied in focused abdominal sonography for trauma) is not available; however, such techniques are time-consuming, result in exposure of a cardiac injury through a very small incision, and lead to a secondary thoracic operation. A transdiaphragmatic pericardial exploration at the time of laparotomy⁷⁹ has been reported to be effective in patients who sustained combined thoracoabdominal injuries.

Figure 75–2 The technique for performing pericardiocentesis. A 16- or 18-gauge needle is attached to an aspirating syringe and inserted along the left lateral border of the xiphoid. The needle is introduced toward the posterior aspect of the left shoulder at an approximate 45-degree angle to both the frontal and sagittal planes.

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