August 11, 2012 by EmerJencyWEBB
Below is some of my notetaking from the literature regarding blunt and penetrating cardiac trauma. Preparation for my senior lecture continues.
NOTES FOR BLUNT CARDIAC INJURY (BCI)
Causes include any form of direct trauma to chest including MVAs, falls, CPR
Histological Changes of Myocardial Contusion: myocardial muscle necrosis with red cell and polymorphonuclear leukocyte infiltrate. Resultant scar band formation after healing.
Location: Right ventricle most susceptible. If involved, left heart valves (mitral and aortic) more susceptible than right heart due to higher pressures. Coronary injury and pericardial injury also possible.
History: Chief complaint usually precordial pain unrelieved by pain medication after direct chest wall trauma.
Physical Exam: may include new murmur if valve involved, signs of fluid overload including JVD and S3 gallop if systolic function impeded, signs of tamponade if applicable
Associated Injuries: Significant BCI primarily seen with significant chest wall and lung trauma. However, sternal fracture alone does not predict cardiac injury.
The Role of ECG
Poor sensitivity for right heart involvement. Specificity also lacking due to co-morbid disease prior to and directly from trauma can alter patients’ ECG characteristics.
Most common abnormalities: non specific ST-T wave abnormalities, ventricular extra-systoles, RBBB. However, a broad range of abnormalities have been shown to exist in patients admitted with blunt chest trauma including a variety of AV and interventricular blocks, as well as arrythmias including atrial fibrillation and ventricular fibrillation.
In one study, patients with history of blunt chest trauma but no other complicating features were admitted for serial ECG. 4 of 171 patients in this group had ECG changes within 24 hours. However none of these patients suffered complications, or were deemed to have significant cardiac injury.
The Role of Cardiac Enzymes
CK-MB fraction is no longer recommended as a screening modality for blunt cardiac injury. Non-specific leaks from traumatized non-cardiac tissue (skeletal muscle, tongue, diaphragm, etc…) may provide false-positives, especially in the poly-trauma population.
Troponin I and T testing is generally considered more specific than sensitive for blunt cardiac injury. Conflicting literature exists as to the timing of testing, necessity of repeat testing, and the overall utility of obtaining these isoenzymes in the screening evaluation in patients with chest trauma. Most newer studies add these enzymes in patients at intermediate risk of cardiac injury, those with new ECG changes, and those patients who are hemodynamically unstable.
The Role of Radiography
The most useful agreed upon study of choice is the echocardiogram, which can provide information on ejection fraction, wall motion abnormalities, valvular function, pericardial effusion.
Angiography has been recommended as the study of choice if any signs of ischemic or infarct are seen on ancillary testing.
Sudden death due to chest wall blow
Typically described in organized athletics (primarily baseball), in young participants.
In one study, a quarter of those who suffered from commotio cordis were wearing chest protectors (found to be poorly fitting, or moved to inadequate position during play)
Most common initial rhythm: Ventricular Fibrillation
The Sweet Spot: 30 mph impact with small dense object, impact directly over cardiac silhouette left of sternum, 10-30 msec prior to the peak of the T wave, from depolarization primarily caused by mechano-sensitive ion channels
Prognosis: 15% survival rate, particularly if resuscitation was initiated in first 3 minutes of injury
<1.1% of cases presenting to the ED, nearly uniformly fatal and most die on scene.
Atria at greatest risk due thin walls.
Likely caused by one of the following mechanisms: crush between sternum/spine, increased intrathoracic pressure, s/p focal myocardial injury (contusion/laceration), acceleration/deceleration mechanis
Cardiac luxation is the term used for cardiac herniation and volvulus, which can result in superior vena cava obstruction or right heart strain.
It is the most serious complication of pericardial rupture, occurring in 28% of cases…and in the setting of trauma has a mortality rate as high as 67%.
Role of Imaging in Penetrating and Blunt Injury to the Heart
Co SJ, et. al. Radiographics. Vol. 31. July 2011. Credit also to image below.
The screening of blunt cardiac injury is not universally agreed upon, and may vary widely on an institutional basis. Below are published algorithms suggested in the literature.
EAST Guidelines for Blunt Cardiac Injury Screening
J Trauma. 44(6):941-956, June 1998.
Initial Management and Resuscitation of Severe Chest Trauma
Bernardin B, and Troquet J. Emergency Medicine Clinics of North America. Vol. 30, Issue 2. May 2012.
Diagnosing cardiac contusion: old wisdom and new insights
Sybrandy KC, et. al. Heart 2003 May; 89(5): 485-489
Blunt Cardiac Trauma
El-Charmi MF, et al. The Journal of Emergency Medicine. Vol 35, Issue 2, August 2008, Pages 127-133.
Also expert opinion from the blogosphere:
On suspected myocardial contusion and new ECG changes by Dr. Steven Smith:
After this case, were I to see a similar one, I would:
1) do a formal echocardiogram on anyone with new significant ECG abnormalities.
2) consider an angiogram if there is ST elevation (as here) and a wall motion abnormality
3) measure troponins, as a very high peak troponin would confirm large territory of contusion
3) limit physical activity if there is concern for a large area of contusion.
And sage advice from the Trauma Professional himself, Michael McGonigal M.D.
Diagnosis is relatively simple: any trauma patient with a likely mechanism who has chest wall pain and a new arrhythmia or cardiac pump failure has a cardiac contusion. Atrial or ventricular arrhythmias are significant, but a ventricular one is significant because it can degenerate into v-tach or worse.Enzyme measurements do not indicate severity of injury or outcome and should not be obtained.
Remember, true cardiac contusion is rare! If suspected, telemetry is indicated, along with frequent vital signs. Cardiac enzymes should not be ordered, and any indication of cardiac problems (arrhythmia or failure) should be reported and treated promptly.
NOTES FOR PENETRATING CARDIAC INJURY
Gunshot wounds have higher associated mortality than stab wounds. In one study, rates were 77% vs. 42% respectively. In another, 86% vs. 32%.
Cause of death usually tamponade or exsanguination. Direct laceration of coronary arteries and valves can also occur, leading to dysfunction and pump failure.
Most injuries occur within the “Cardiac Box”, although injuries outside this location may produce equally fatal cardiac injuries. Therefore, a high index of suspicion must be maintained when dealing with penetrating trauma directly to or around the thorax (including the upper abdomen).
Tamponade may ensue with very little pericardial blood accumulation. Echocardiography and FAST exam, have supplanted the use of subxiphoid window, to detect pericardial effusion in the emergency setting.
Treatment mandates emergent surgical repair.
Due to the high mortality associated with such wounds, and the lack of efficacious field interventions for penetrating cardiac trauma, a pre-hospital “scoop and run” strategy has been preferred.
Beware intubation in patients with penetrating chest injury. Intubation and positive pressure ventilation may precipitate loss of sympathetic tone in actively exsanguinating patients (causing precipitous drop in BP), cause impending tamponade to manifest itself, or cause air embolism from anunrecognized bronchial/pulmonary vein traumatic fistula. Think carefully prior to performing this procedure in the ED if it can be completed expeditiously in a more controlled OR setting.
Special Case: Foreign Body Emboli
Venous bullet emboli may result if penetrating missile acquires access to the systemic circulation through penetration of vessel walls. Rare, but interesting.
EMERGENCY DEPT. THORACOTOMY FOR BLUNT AND PENETRATING CARDIAC INJURY
Generally the same for both adult and pediatric populations.
Must have prior signs of life (SOL) – breathing spontaneously, reactive pupils, electrical cardiac activity, GCS > 3. (< 5 minutes for blunt injury, < 15 minutes for penetrating injury)
Persistent hypotension failing resuscitation, perceived to be from thoracic source.
Or if extra-thoracic source, may be used to staunch flow of blood out of chest by cross-clamping aorta.
Scott Weingart tipped us off to this chart, which displays the indications pretty well.
Another great set of tables out of the Journal of Royal Army Medical Corps regarding technique and what to do once inside the chest:
As for blunt injury and wielding the knife, from the same article above:
The liberal application of thoracotomy in the resuscitation of blunt trauma cannot be justified and should only be undertaken when there are documented signs of life in the emergency department or within five minutes prior to arrival; prolonged (>5mins) CPR after blunt injury equates to fatality.
For further detail into cardiac repair technique, check this article out:
All credit to above material goes to references in the Comments Section below.