Traumatic Cardiac Contusions
Traumatic cardiac contusions can happen after blunt trauma at high velocities such as a motor vehicle accident in which the patient’s chest wall strikes the steering wheel, the dashboard, or even an airbag. The signs and symptoms can be as minor as chest pain and bruising or as severe as a cardiac wall rupture, which is usually fatal. Traumatic cardiac contusions can be difficult to diagnose and, if treatment is necessary, it often involves open heart surgery, with its inherent risks.
No one knows the exact incidence of traumatic cardiac contusions following chest trauma in a motor vehicle accident. Articles in the literature have reported as little as 7 percent incidence of significant cardiac contusion to as high as 71 percent in other studies. What is known is that, among those people who die from motor vehicle accidents, traumatic cardiac contusions contribute to 20 percent of those deaths. The true incidence of traumatic cardiac contusions may not be known because a proportion of these patients will die at the scene or will die from other trauma sustained at the time of the accident.
One study from 2004 revealed that contusion to the myocardium was the most common blunt cardiac injury and that injury was more common to the right atrium and right ventricle, owing to the anterior position of these parts of the heart. More rarely, left sided damage can occur with about 8-15 percent of injuries involving the left ventricle and less than 0.31 percent of injuries involving the left atrium. Injuries to the valves, the septum of the heart and to the coronary arteries were even more uncommon.
How does this injury happen?
The heart is well protected by the bony thorax, which is made up from the ribs and bony sternum. This means that it takes a great deal of force in order to cause a traumatic cardiac contusion—the kinds of forces only seen in relatively high impact motor vehicle accidents in which the victim was improperly restrained or the frontal collision was relatively severe in nature. While most injuries are the result of motor vehicle accidents and pedestrian-motor vehicle incidents, traumatic cardiac contusions can also occur secondary to falls from great heights, direct blows to the chest during sporting events, and thoracic crush injuries in industrial situations.
Besides direct trauma to the chest wall itself, severe compression injuries to the abdomen can result in a sudden increase in the flow of blood to the heart from the inferior vena cava. This causes rupture of the right atrium or right ventricle because of a sudden increase in the pressure of the blood within the heart itself.
The coronary arteries themselves can be traumatized during a chest wall injury. When this happens the inner lining of the artery becomes disrupted and a thrombus forms, causing the equivalent of an acute myocardial infarction that is trauma-related rather than due to any innate cardiac disease. More often than not, this injury is also associated with severe traumatic cardiac contusions, which further injures the heart. The left anterior descending artery is the most common coronary artery involved in a cardiac contusion. When this artery is damaged and a thrombus forms, there can be the following secondary complications:
- Emboli coming off the coronary artery
- Left ventricular failure
- Cardiac arrhythmia
- Later ventricular rupture
Valvular injuries are uncommon but are due to an increase in the pressure inside the heart that blow out the chordae tendinae and papillary muscles that support the valves. Of the four main valves in the heart, the aortic valve is most commonly affected, followed by the mitral valve. Patients suffering from these types of injuries usually suffer from cardiogenic shock secondary to severe left sided ventricular failure.
The pericardium surrounding the heart can be ruptured following blunt trauma to the chest wall but this is uncommon. Unfortunately, it is often the result of the most severe types of blunt cardiac injury. Pericardial rupture happens when the chest and abdomen are both crushed so that the diaphragm and surfaces of the lung are disrupted along with the pericardium. In severe cases, there can be disruption of the diaphragm with damage to the phrenic nerve and herniation of the heart into the abdominal cavity or elsewhere in the chest. The major vessels often get twisted so that cardiac output is impossible, leading to death from a cardiac arrest.
It is important to recognize that, when a traumatic cardiac contusion occurs, it almost always occurs in a setting of multiple areas of trauma with sternal fractures, rib fractures, tension pneumothorax, pneumothorax, bruising of the lungs and blood in the thoracic cavity. Any time these other injuries are seen, the possibility of a traumatic cardiac contusion needs to be considered.
How is a traumatic cardiac contusion diagnosed?
The doctor needs to have a high index of suspicion whenever a patient presents after a car accident in which chest trauma was sustained. Many patients will be in emotional or physical shock so that they do not have symptoms other than chest wall tenderness. Severe cases of cardiac contusion can result in cardiogenic shock and the major findings will be low blood pressure, a tension pneumothorax, and low blood volume (hypovolemic shock).
There are several ways to attempt to diagnose a cardiac muscle contusion. These include the following tests:
- Electrocardiogram, which may show evidence of myocardial injury
- Chest x-ray, which might show displacement of the heart, rib and sternal fractures or other injuries
- Cardiac enzymes, which can be nonspecific to the heart but, if normal, can rule out significant damage to the cells of the heart
- Holter monitoring, which can show episodes of arrhythmia in the heart
- Transthoracic echocardiogram
- Transesophageal echocardiogram
- Nuclear medicine studies
Sometimes several of these diagnostic tools are necessary to make the diagnosis of probable cardiac contusion. There is no single test that can absolutely prove the presence of a traumatic cardiac contusion so several testing strategies may need to be employed. One of the best strategies is to do a troponin T level, which is relatively specific for myocardial injury along with an EKG, which may show changes in the cardiac wave form or an increase in arrhythmias. A cardiac echo examination may be able to show portions of the heart that do not contract as well as the rest of the heart along with abnormalities of the valves. The transesophageal echocardiogram tends to be a better test than a transthoracic echocardiogram examination. Radionuclide scans have been used in the past to show areas of damage to the heart but, because it is such a nonspecific test, it is rarely used today.
Grading of Blunt Cardiac Injuries
There is a grading scale that can help determine the severity of injury to the heart. The grading scale looks like this:
- Grade I. In such cases, there are nonspecific findings in the ST segment and T waves on EKG with a contusion to the pericardium but no obvious injury to the heart itself. There is no rupture of the pericardium nor is there herniation of the heart through the diaphragm or pericardial sac.
- Grade II. There are changes in the EKG noted, such as a complete heart block or ST segment changes without evidence of heart failure. It can also represent a penetrating wound to the heart that does not extend all the way through the heart muscle and does not cause cardiac tamponade.
- Grade III. There are multiple PVCs seen on EKG along with blunt trauma to the heart with septal wall rupture, incompetence of either the tricuspid or pulmonary valves, damage to the pericardium with herniation of the heart and/or penetration of part of the heart muscle but not going through the endocardium. Cardiac tamponade is present.
- Grade IV. There is myocardial injury associated with valvular incompetence, septal rupture, coronary artery blockage, cardiac failure and/or specific blunt or penetrating injury to either atria of the heart or the right ventricle.
- Grade V. Proximal coronary artery occlusion has occurred, usually of the left anterior descending artery with left ventricular involvement. There can also be injury to the right ventricle but involving less than fifty percent of the right ventricular muscle damaged.
- Grade VI. There is severe blunt avulsion of the heart or penetrating injury to the heart that results in more than fifty percent loss of any chamber in the heart.
Monitoring of a Traumatic Cardiac Contusion
Proper monitoring of a cardiac contusion or suspected cardiac contusion involves getting a baseline EKG followed by cardiac monitoring if the EKG is abnormal. If the patient appears to be unstable, an echocardiogram should be performed to look for wall motion abnormalities. As mentioned, a transesophageal echocardiogram is more sensitive than a transthoracic one. Close monitoring should be performed on patients who require surgery for their traumatic injuries. While troponin levels and levels of other cardiac enzymes can diagnose a cardiac contusion, they are not specific and will not be able to predict those patients that will go on to suffer serious complications.
I’m Ed Smith, a Sacramento personal injury attorney with the primary accident information site on the web, AutoAccident.com. I have had extensive experience with cardiac contusion and heart injury cases,
If you or a loved one has suffered a serious injury, call me now at 916.921.6400.
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