Abstract
Acute thoracic aorta dissection can happen for many reasons and is a severe disease that needs to be diagnosed and treated very rapidly. The speed at which a diagnosis is made can make all the difference in whether a patient does or does not survive. The emergency room diagnosis usually consists of ECG, chest x-ray, physical exam, and TTE.[1] which may then lead to the need for CT scanning, MRI, and angiography. Generally, any laboratory testing is done to rule out other problems. However, recently the d-dimer has become more important. The case study discussed in this paper includes the use of the d-dimer which in this case caused a 72-hour delay in care.
Background
Acute aortic dissection is a dramatic clinical presentation on average. Even so, the fact is that clinical suspicion is often absent. The average patient with acute thoracic aortic dissection presents to the emergency room with severe chest pain, back pain, a migratory type of propagating pain, or ripping and tearing sensation in the chest. There are also patients with the condition that occasionally present with pain at all, this is about 15% of the time. [2] The symptoms of retrosternal chest pain with scapular involvement may be thought of as acute MI or it might not occur and the diagnosis may be missed until it is life-threatening. [2]
Aortic dissection is known to occur spontaneously for many reasons, some of which are hypertension and Marfan’s syndrome or it may happen because of post-op surgical complications. Whatever the reason for it to occur, it is a life-threatening problem that must be diagnosed and treated quickly. That diagnosis is often made with a TEE (transesophageal echocardiography) of MDCT (multidetector computed tomography).[3] More recently, it has also been discovered that d-dimer levels are elevated in patients that have acute thoracic aortic dissection. Elevated d-dimer results have been shown now in several studies involving ATAD.
A recent study by Weber et.al. in which D-dimer was done on every patient that had a positive study for ATAD showed a positive D-dimer is very significant. The mean value in each case ranged from 9.4 and ranged from.63 to 54.7. It is also important to note that there were correlations between the severity of the abnormal result in the D-dimer and the severity of the dissection.[2] It would seem from the results of studies like this one that if there are any positive indicators or if there is great suspicion, a D-dimer should be done.
With all of these abilities to do a primary diagnosis rapidly, it is still often difficult to assure a diagnosis fast enough to make a difference in ATAD. Many of the other tests may not show positive until the patient is already in a critical condition.[4] A rapid test must be found for that reason. One would hope that the D-dimer is studied extensively to show that it is a diagnostic tool or not, as many are still not convinced.
Case Presentation
The patient presented to the emergency room with sudden sharp upper chest pain with pain at the side of the neck. She is a 78-year-old female patient who is normally pretty fit and able. Her chest x-ray shows cardiomegaly with a normal ECG. Her D-dimer is positive at 2.62. There were no further tests in the emergency room and the following day the patient had a CTPA which showed type A dissection from the Aortic valve up to the arch. An urgent echo showed agreement in the diagnosis
Like many patients with ATAD, the diagnosis is not clear in the beginning. However, in this case, the pain fits the type of pain that might be noted in a patient with ATAD and her D-dimer is positive. This might have led one to do the echo and the CTPA right away instead of waiting.[5] Though the surgery was performed later than might have been liked (36 hours after admission), there was a positive result. She remained hemodynamically stable and continued with good left ventricular function as well as good right ventricular function. She had a longitudinal intimal tear in the distal ascending aorta 10 cm distal to coronary ostium with minor surface atheroma according to the case report.
Studies have been done on using chest x-ray in the diagnosis of CTPA, which is the test that this patient had in the ER. Those studies have shown that the greatest number of positive patients with CTPA show a positive initial chest x-ray showing cardiomegaly 57% of the time. This, too, is significant but needs more study.[2]
Discussion
In this case, study a woman who is elderly but in good condition and healthy presents to the emergency room with pain that is typical of MI or ATAD. Her chest x-ray shows cardiomegaly and the only other test done is a positive D-Dimer.[6] She is then admitted to the hospital and testing the following day which is 36 hours after admission shows a positive ATAD for which she goes to surgery and does well.
This is very typical of the patient who enters a hospital with an ATAD through the emergency room and the fact that the diagnosis was missed is also not unusual. [7] It is very difficult to do a differential diagnosis at this time. Many patients present with no pain at all and those that do have pain are also closely typical of MI. To determine which the physician is dealing with requires a differential test. The D-Dimer is being studied as that test. However, there is still much disagreement among physicians and researchers, as to whether it is the test that they need to depend on to make this differential diagnosis. Many of the studies are showing a positive D-dimer when other tests are positive but there is still some suspicion.
Much work still needs to be done. Research into this subject is extremely important because this is a diagnosis that cannot afford to wait. Many patients die while the diagnosis is being made, unlike the case study here. Rapid diagnosis and treatment are a priority. Future studies must concentrate on determining how accurate the use of the D-dimer is and how much it can be depended on to make this diagnosis
Conclusion
In conclusion, this patient might have been in the OR much sooner had there been an understanding of the positive D-Dimer. Research has shown that the positive results with the symptom logy that this patient showed were a good indicator of ATAD. This particular patient did well but might very well not have. The D-Dimer is being used more and more often as an indicator but there needs to be more study to support increasing use in diagnosis. Further study to determine what other testing might be used for rapid diagnosis is also important. The D-Dimer though it is showing improved use may not be the best test to use. Because of the rapid deterioration of these patients, that test should be found.
Works Cited
Weber T et.al. D-dimer in acute aortic dissection. Chest 2003; 123(5)1375- 1378.
Gregorio M et.al. The presenting chest roentgenogram in acute Type A aortic dissection. The American Surgeon 2002;68(8) 6-12.
Tabry et.al. Acute aortic dissection. Texas Heart Institute Journal 5, 2009; 36(4) 462-467.
Perez A et.al. D-dimers in the emergency department evaluation of aortic dissection. Academic Emergency Medicine 2004 11(4); 397-400.
Hazui H et.al. Simple and useful tests for discriminating between acute aortic dissection of the ascending aorta and acute myocardial infarction in the emergency setting. Circulation Journal 2005; 69(6); 677-82.
Das KM et.al. Coronary artery dissection with rupture of aortic valve commissure following type A Aortic Dissection. Journal of Cardiac Surgery 2008;23;548-550.
Akutsu K et.al. A rapid bedside D-dimer assay for screening of clinically suspected acute aortic dissection. Circulation Journal 69(4);397-403.