U Yetkin, ? Yürekli, S Bayrak, C Özbek, ? Özsöyler, A Gürbüz
blunt trauma, cardiac injury, echocardiography
U Yetkin, ? Yürekli, S Bayrak, C Özbek, ? Özsöyler, A Gürbüz. Cardiac Injuries Due To Blunt Trauma. The Internet Journal of Thoracic and Cardiovascular Surgery. 2008 Volume 13 Number 1.
Blunt cardiac trauma develops frequently following motor-vehicle accidents and its mortality rate is high. Early use of echocardiography for the initial assessment of severely injured patients has facilitated to detect the associated cardiac injuries. Fast transportation, urgent diagnostic workup and immediate surgical intervention to these patients with well-trained teams are very important and this approach will improve their survival.
Introduction and Brief History
Although cardiac injuries have been known since ancient era, their surgical interventions couldn't have been possible until 19th century. In 16th century, Fabricius reported that cardiac injuries resulted in sudden death and that it was impossible to treat these injuries; even an attempt made to treat was unnecessary. First case with cardiac injury was reported by Oluff Borch. First case with myocardial contusion was defined Akenside in 1764. Pericardiocentesis as a treatment modality for cardiac injury was first recommended by Riolanus in 1649. But first successful pericardiocentesis was performed in 1829 by Larrey. Suturing a cardiac wound was first recommended by Roberts in 1881. Between years 1882 and 1885, surgical correction of cardiac wounds in experimental animals were reported. In 1897, Rehn reported the first successful repair of a penetrating cardiac wound (1).
Among the causes of death in all age groups, deaths due to trauma rank third after cardiovascular diseases and cancer (2). Recently, most common cause of death under age 40 is accidents. Until age 40, chest trauma constitutes 20-25% of the causes of deaths due to trauma (3). Seventy five percent of chest traumas due to blunt or penetrating injuries are accompanied by injuries of other organ systems (4,5). Twenty five percent of deaths due to blunt trauma are constituted by chest injuries where chest trauma is an aggravating factor in 50% (4).
In our country, mean age of adults experiencing thoracic trauma ranges between 38 and 43 (3,4,6). Thoracic traumas are known to be more common among males (4,6). The incidence of blunt thoracic trauma ranges between 58.7 and 75.8%, whereas that of penetrating thoracic trauma ranges between 24.1 and 41.3% (3,4,6,7).
Etiology and Pathophysiology
In the past century advances in science and technology generally influenced quality and duration of human life positively. Unfortunately, this is not true for deaths caused by injuries, particularly of motor vehicular accidents (8,9).
Blunt cardiac injuries occur due to motor vehicular accidents, sport games, animals, fall from heights and blow during fights. Moreover, they could also happen during external cardiac massage iatrogenically. Most common mechanism of blunt cardiac injury is crushing (4,10).
Cardiac injuries take place as high as 64% in cases of thoracic organ injuries (11).
The incidence of cardiac injuries after both penetrating and blunt injuries was reported between 0.4 and 6% in national literature (3,4,6). Multisystem injuries occur in many of the thoracic traumas and approach to these cases in emergency services influence morbidity and mortality rates (4). In our country, isolated thoracic traumas were reported in 17.7 to 77.3% of cases with thoracic trauma that were admitted to emergency services (3,4,12). Blunt cardiac injuries are seen in 9 to 38% of cases with severe thoracic trauma (13). In medical literature, thoracic traumas are mostly accompanied by extremity fractures, head traumas and intraabdominal organ injuries, decreasing in frequency respectively (3,4,14). Rib fractures are frequently seen in blunt thoracic traumas (4).
Clinical and autopsy studies pointed out that myocardial injury was defined in 15 to 75% of cases with blunt thoracic trauma. This situation may appear as a wide variety of disorders such as life-threatening arrhythmias, anomalies of conduction system, congestive heart failure, cardiogenic shock, hemopericardium, pericardial tamponade, cardiac rupture, valvular rupture, intraventricular thrombus, thromboemboli, air emboli, coronary artery occlusion, ventricular aneurysm and constrictive pericarditis. This situation may also manifest itself even with no clinical findings (8,15).
Histopathologically, a picture ranging from myocardial edema to necrosis may appear. Histologically, subepicardial or myocardial bleeding, leukocytic infiltration and edema may be seen at different levels (16). Clinical results differ according to whether the structures influenced by trauma are located on the more tolerable right side or not (17). Myocardial injuries may be in the forms of laceration, perforation, septal perforation and shunting, infarction and rupture. Coronary artery laceration and division or cardiac valve rupture may be seen. Clinical picture may show up as tamponade or hemothorax (18).
Signs and diagnosis
Cardiac injury should be definitely suspected in a case with high velocity trauma. Particularly, presence of rib or sternal fracture in anterior chest wall, form of injury, echymosis located in the chest wall, mark of seat belt and/or steering wheel, subconjunctival hemorrhage and the severity of injury should make one think of cardiac injury due to blunt trauma.
Penetrating cardiac injury should be suspected in cases admitted to emergency service with injuries of the zone in between right sternal border, left anterior axillary line, 3rd intercostal space and a line drawn from xiphoid process to the left anterior axillary line (18). In case of shock, thoracic or mediastinal cavity should be reached through an incision next to the entrance without wasting time (18,19).
Generally, these types of cases are lost before reaching a hospital. Most of the patients reaching a hospital develop pericardial tamponade. Partially flexible pericardium can hold a volume of liquid up to 150 ml without increasing intrapericardial pressure. Increased pressure in bleeding beyond this restricts the venous return to the heart. By this way, decreased cardiac output deteriorates peripheral circulation and metabolic acidosis accompanies this situation. In general, this picture ends up with death. Jugular venous distension, peripheral coldness and chills are accompanied by hypotension and faint heart sounds in auscultation. In this picture of shock; triad of severe jugular venous distension, hypotension and faint heart sounds is called Beck's triad. The presence of this triad should suggest cardiac tamponade and urgent pericardial puncture should be carried out to drain blood under sterile conditions. If the patient was taken to the operating room and the pericardium was opened to remove blood, the bleeding sites of myocardium should be localized and repaired. If a patient is in shock or preshock condition and his/her central venous pressure (CVP) is more than 12 mm Hg, pericardiocentesis should be carried out. If the pericardiocentesis fluid is hemorrhagic, the patient should either be taken into operating room or blood/fluid replacement should be done. If rapid venous distension develops and CVP rises up, surgery is again the treatment of choice. If CVP only changes slightly with volume replacement and hemodynamic stability is maintained, either supportive treatment or surgical intervention for hemostasis could be chosen (18,19).
Among the investigations reflecting the blunt cardiac injuries are: CK-MB isoenzymes, radioisotope scanning, continuous ECG monitoring, echocardiography and cardiac catheterization (20).
There is a pathological condition seen after blunt cardiac injury which is called myocardial concussion. Although this pathology doesn't cause any structural abnormality even at autopsy, it was reported that it may cause any type of arrhythmia and sudden cardiac death. These cases usually have normal echocardiographic findings. ECG may reveal ST segment elevations and branch blocks. ST segment elevations are thought to be due to transient myocardial ischemia or coronary arterial spasm (8,22). Myocardial contusion is a more severe pathology than myocardial concussion in cases with chest trauma. ECG changes are not specific. Any type of arrhythmia and ST segment changes may be seen. Sinus tachycardia, atrial flutter or atrial fibrillation are the most common ones. After the injury, a rise of more than 6% in CPK and CK-MB generally points out a contusion. Echocardiographic investigation may reveal pericardial effusion and slowing down of the myocardial contraction (8,22,23). In a study investigating 31 cases with blunt injury, 3.8% had pericardial effusion whereas 3.2% had atrial flutter and 61.5% had various rhythm disturbances (8). Cardiac troponin I (CTI) is the gold standard diagnostic marker for myocardial injury. It is more valuable than CK-MB. Increase in CTI starts within the first hour and continues about 4 to 7 days (18,24).
Echocardiography is getting to be used more commonly in diagnosis of blunt cardiac injuries (20). In blunt cardiac injuries, it is important to be able to perform echocardiography at the emergency service in detecting hemopericardium (18) (Figure 1 and 2).
It is an alternative method particularly in detecting pericardial effusion in blunt trauma cases as it is non-invasive and sensitive. With the aid of this investigation, it is possible to shorten the door-to-operating room time (18,25). Echocardiography is also important in detecting the early and late cardiac sequelae (17). Moreover, it is possible to obtain satisfactory results in evaluating global left ventricular function. Beside that of pericardial fluid collection, it is useful in the diagnosis of structural disorders (20).
If the result of echocardiography is not consistent with hemopericardium, asymptomatic patient should be closely observed for about 24 hours (18,25). If the exact decision still could not be made and there is a suspicion of cardiac injury, subxiphoid pericardial window can be opened (18). Subxiphoid pericardial window is a diagnostic intervention and it reveals cardiac injury. But, it is an invasive method and it is not indicated in cases with no exact diagnosis (18,26).
Intracardiac valvular injury due to blunt thoracic trauma is not commonly seen, but it is important (17). Valvular insufficiencies could occur due to injuries to papillary muscles, leaflets or chordae (8,27). According to the literature, it is most commonly seen in aortic valve, then in tricuspid and mitral valves in decreasing frequency, respectively. In some other literature, tricuspid valve is the most common site (8,13). Severe mitral insufficiency due to rupture of chorda and/or papillary muscle is a seldom complication of blunt thoracic trauma (17) (Figure 3,4 and 5).
Pathologies related to the aortic or mitral valve usually proceed more severe and require early surgical intervention (8,28). In tricuspid vale injuries, papillary muscle rupture requires surgery within several months whereas chorda rupture requires surgery within 10-25 years (8). The incidence of cardiac and major vascular injury in blunt thoracic trauma changes between 4 and 15%. Very seldom, left ventricular aneurysm may develop. In pathogenesis of this situation; contusion, vascular lesion causing myocardial lesion and intramyocardial dissection are effective (18). Particularly, injury to the left anterior descending artery may cause a typical left ventricular aneurysm (1,20). In a case with thoracic trauma, after first resuscitation, if ventricular septal rupture symptoms or signs were detected, cardiac catheterization is performed after stabilization. If left-to-right shunting is below 2, each patient should be followed. If this shunting is more than 2, patients go to surgical therapy with the aid of intraaortic balloon pump, when necessary (18).
Treatment and conclusion
In cases with suspected blunt cardiac injury, emergent care is necessary while the treatment protocol in Table 2 remains valid for a proper approach (1,20,21).
Since cardiac injuries may rapidly proceed to sudden death, rare number of injured patients could reach the hospitals (8). But developments in ambulance and health services would increase the number of successfully treated cases. In patients facing up to trauma; emergent first intervention, fast transportation, rapid evaluation with tele- and echocardiography and immediate surgical approach with the use of cardiopulmonary bypass when necessary are life-saving steps (18). Besides rapid relief of tamponade; control of bleeding, obtaining normal cardiac functions and simultaneous intervention to the accompanying organ injuries are the principles of treatment strategy. Moreover, since the most common cause of blunt cardiac trauma is vehicular accident, rising public awareness of the traffic rules is important (4).
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