Injury to the heart in blunt chest trauma is dependent on a number of factors. Symptoms are often non-specific, and there is no gold standard test for diagnosis. Injuries to small areas of the myocardium may only be identified at autopsy. We report a 38 year old man who sustained a number of injuries in a road traffic accident, and in whom the single clinical or ECG abnormality was a left bundle branch block (LBBB); he had a myocardial injury rated as grade II. The patient was treated for his injuries and later discharged. As this is a difficult diagnosis, algorithms of blunt chest trauma may save time and money by avoiding misleading diagnosis and unnecessary monitoring and admissions.
- blunt chest trauma
- myocardial contusion
- bundle branch block
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Injury to the heart in blunt chest trauma is dependent on the magnitude of force applied to the chest, the area over which it is applied, the compliance of the chest wall, and the timing of the application of force during the cardiac cycle. Symptoms are often non-specific and physical signs frequently absent. An initial abnormal ECG may help to identify patients with blunt cardiac trauma, but normal studies lack negative predictive value. Cardiac isoenzymes alone are also not helpful. The role of troponin levels is not yet clear. Echocardiography is useful in clinically severe blunt cardiac injury.
Recently, a retrospective review has showed that the majority of patients identified as having “myocardial contusion” (blunt cardiac trauma) sustained their injuries as a result of a motor vehicle crash, and that the most frequent additional injuries were rib fractures, pulmonary contusion, and closed head injuries.1
Injuries to anatomically small areas of the myocardium may be identifiable only at autopsy, and often have little clinical expression or impact on contractility, but they become evident if they alter the electrical properties of the heart (conduction abnormalities and arrhythmias). A transient right bundle branch block was the most common conduction abnormality in that review, as has been noted previously, probably because of its anterior anatomical location and proximity to the sternum.
Mortality was found to be associated only with severe injuries (grade IV or greater of the Organ Injury Scale of the American Association for the Surgery of Trauma (ATLS)).2
We describe a myocardial contusion case where the single clinical or ECG abnormality was a left bundle branch block (LBBB), rarely reported in the literature.
A 38 year old white man was admitted to our emergency room following a motor vehicle crash. The initial evaluation, according to ATLS protocols, showed patent airways (cervical belt present), reduced left hemithorax expansibility and auscultation, and extensive subcutaneous emphysema, Heart rate was 96 beats/min and arterial pressure 120×80 mmHg. He was confused (Glasgow Coma Scale 14). As the patient was apparently drunk (alcoholic breath) he underwent an abdominal ultrasound evaluation (focused assessment with sonography for trauma (FAST) approach) that did not show free liquid pattern. The chest radiography (fig 1) showed wide subcutaneous emphysema, pneumothorax, and alveolar opacities in inferior left hemithorax associated with fractures of the second to fifth ribs at different points (flail chest).
The patient underwent closed system chest drainage without significant haemothorax and adequate lung expansion. The complementary neurological evaluation, including head and cervical CT scan, did not show abnormalities. The chest CT scan showed non-significant bilateral pleural effusion, greater on the left, with opacities on inferior lobes, multiple rib fractures, left scapula fracture, subcutaneous and soft tissue emphysema, little pneumomediastinum, patent trachea and main bronchi, and no heart or base vessel abnormalities.
The patient remained hemodynamically stable during the whole evaluation time without abnormalities on continuous cardiac monitoring. He was transferred to the surgical intensive care unit (ICU) with a diagnosis of blunt chest trauma and severe pulmonary contusion. He was awake, reporting dyspnoea (28 inspirations/min) while on supplemental oxygen delivered by face mask (5 l/min), and presenting paradoxical breathing (left hemithorax); his mean arterial pressure was 100 mmHg, heart rate was 110 beats/min and he had a normal 12 derivation ECG (fig 2). He received 4 litres of crystalloid fluids during the resuscitation period in the emergency room.
Once stable, the patient received analgesics and a respiratory therapy programme, including intermittent non-invasive ventilation (bi-level positive airway pressure). Eighteen hours after his ICU admission, he developed a widening of the QRS complexes on cardioscope, without symptoms, and ECG showed sinus rhythm (88 beats/min) with left bundle branch block (LBBB) pattern (fig 3) with spontaneous reversion after almost 40 minutes. Blood was taken for measurement of troponin I after this event, and gave a result of 1.8 ng/mL (normal <2.0 ng/mL). Obviously, his creatinine phosphokinase was extremely elevated from the accompanying skeletal muscle injuries. According to the Organ Injury Scale, the patient had a grade II myocardial injury.
The patient did not have a past medical history of hypertension or ischaemic heart disease, nor of smoking or dyslipidaemia. On the second and fifth in hospital days, a new LBBB pattern with variable frequencies, without hypotension or any symptoms, was observed. Transthoracic echocardiography demonstrated discinetic motion of the septal wall (without LBBB pattern on cardioscope), minor pericardial effusion, no valvular incompetence, and preserved ventricular function.
During his clinical course, the patient’s respiratory status worsened, with a sudden fall in thoracic drainage output and a large pleural effusion in the left haemothorax on chest radiograph. New chest drainage was performed but it was not fully effective; a new chest CT scan showed loculated pleural effusion, and thoracoscopy was used to guide the drainage and washing of debris from the pleural space, with satisfactory radiological and clinical improvement.
Although the patient did not develop new intermittent LBBB pattern episodes, he underwent a new echocardiography that confirmed the discinetic septal motion. He was discharged of from ICU to an intermediate care facility with the chest drain, and after 1 week of respiratory therapy care and pulmonary re-expansion techniques (including incentive spirometry), he left the hospital.
Regardless of the definition of BCT, this entity becomes important only when it is associated with significant symptoms, such as arrhythmias or hypotension, or causes anatomical defects, such as valvular, septal, or free wall rupture. Electrocardiographic abnormalities have been reported to be the most sensitive screening technique for myocardial contusion. However, some studies have contradicted this, because the right ventricle most commonly sustains injury due to its anterior location beneath the sternum, while the left ventricle has large mass and generates larger voltage potentials.
In a study by Torres-Mirabal et al3 in 36 patients with myocardial contusion, 58 ECG abnormalities were described. None was an LBBB. Bertinchant et al4 have published ECG findings in 94 patients with suspected myocardial contusion: nine cases with right bundle branch block, but no LBBB cases reported. Cachecho et al5 have reported the clinical significance of myocardial contusion in 336 victims of blunt chest trauma, with 19 bundle branch blocks but no obvious LBBB citations.
As LBBB may be also a manifestation of ischaemic heart disease, to differentiate a diagnosis of acute coronary syndrome from a myocardial contusion in a patient such as a 50 year old man, with several risk factors for coronary artery disease, a victim of BCT, could be difficult. Assessment of ventricular function, continuous cardiac monitoring, and determination of specific cardiac enzymes are potentially useful.
We report a rare myocardial contusion manifestation in a young trauma victim. As no one single test has been considered the “gold standard”, algorithms of blunt chest trauma may save time and money by avoiding misleading diagnosis and unnecessary monitoring and admissions.
Competing interests: none declared
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