The Common Vein Copyright 2009
Author: Juan Carlos Leoni M, MD·
CLINICAL CONSIDERATIONS:
This document will provide an approach to the radiological modalities currently used to determine the etiology of atypical chest pain, which has become a diagnostic and radiological challenge to the general practitioner who often encounters this scenario on his daily activity. The initial encounter with a patient complaining of chest pain consist on a detailed clinical history, physical examination, 12 lead electrocardiogram and biochemical markers for myocardial ischemia. In a subgroup of these patients, we may as well confront patients who do not fit the classical chest pain history. These are the patients that we categorize as having ?atypical chest pain?, presenting with symptoms that do not lead to a specific diagnosis, and their initial workup for acute myocardial ischemia is not supported by the testing modalities mentioned above.
WHAT SHOULD BE THE INITIAL RADIOLOGIC APPROACH?
The initial imaging study for atypical chest pain that should be pursued if the clinical history and physical examination are not helpful, is a simple chest X-ray. This is a simple, cost-effective and widely available test that permits excluding other conditions that may present as atypical chest pain, including pneumonia, pneumothorax, congestive heart failure, or chest wall abnormalities including fractures.
IF CHEST X-RAY IS NOT HELPFUL, THEN WHAT?S NEXT?
Many conditions, including gastrointestinal etiologies (which are the most common cause of atypical chest pain) are not clinical significant on chest X-ray. At this point, the direction of further imaging modalities should be dictated be the clinical manifestations that the patient describes, the availability of radiological tests as well as specific specialist services, the cost-effectiveness of the testing (financially some tests may create some burden in the pursue of a specific diagnosis), the timing to reach a diagnosis as well as the clinical scenario.
In order to present a succinct review to approach imaginologically the causes of atypical chest pain, we will target its most common causes by organ system, with a brief outline for every radiological investigation.
1) GASTROESOPHAGEAL SYSTEM:
a. Gastroesophageal reflux (GERD)
This entity comprises the most common cause of atypical chest pain, and it can be approach by a good history as well as response to symptomatic treatment. Although in most cases it does not require a specific investigation, an upper esophagogastric endoscopy (EGD) is the test of choice to reveal the nature of the disease. Another approach to document this disease is a barium swallow. The barium swallow is performed when the whole esophagus needs to be evaluated and includes an evaluation of the cervical, thoracic and abdominal esophagus together with the gastro-esophageal (GE) junction. If the patient is able to swallow easily, both a double contrast (air and barium) as well as a single contrast study is performed.· The double contrast study enables optimal visualization of the mucosa, while the single contrast evaluates the peristaltic function as well as an overall appearance of the mucosa.· The radiologist usually decides whether the patient will be able to tolerate the double contrast study.·Of note, the stomach is not evaluated in a barium swallow.
b.) Hiatal hernia: although usually asymptomatic, this condition may as well cause atypical chest pain. As above, it can be seen on barium studies, EGD, computer tomography (CT) scans, and even chest x-rays.
c.) Peptic ulcer disease (PUD): when suspected, it can be determined by EGD. The use of other imaging modalities is primarily to evidence peptic ulcer perforation as a complication from this condition. Chest X-ray may indicate free gas under the diaphragm (pneumoperitoneum), which can be visualized as well with CT scans of the chest or abdomen.
d.) Disorders of the gallbladder: acute cholecystitis may present with atypical chest pain instead of the classical right upper quadrant pain. Ultrasound is the investigation of choice in a patient with suspected acute cholecystitis and can also provide information on liver, pancreatic and renal lesions. It has a positive and negative predictive value close to 99%, and it will be indicated when there?s presence of a sonographical Murphy sign, that is, a positive reproduction of the clinical Murphy sign when the operator presses the ultrasound probe on the gallbladder. It may also show a gallbladder wall thickening of more that 3 mm, the presence of gallstones (which may be impacted or not at all) and pericholecystic fluid. It is relatively inexpensive and non-invasive but may be somewhat operator dependent, and also limited in patients with large body habitus. On the other hand, a triad of jaundice, fever and RUQ pain (Charcot?s triad) is indicative of cholangitis, which has a high mortality if not treated promptly with appropriate antimicrobials. This condition is diagnosed clinically, and cannot be diagnosed with ultrasound.
e.) Other disorders of the hepatobiliary system:·these will include choledocolithiasis, malignancy, strictures and others. The radiological approach of these disorders includes a CT intravenous cholangiogram and the magnetic resonance cholangiopancretography (MRCP). This two modalities have the advantage over endoscopic retrograde cholangiopancreatography (ERCP) in being not invasive thus avoiding procedural complications like pancreatitis, detecting lesions beyond the mucosal surface, are less expensive and do not require sedation. The downfall is that they are only diagnostic and do not permit immediate treatment or tissue biopsy.
f.) Pancreatitis: although tipically diagnosed clinically, CT scan of the abdomen is the imaging modality of choice not only to assess its presence but also to determine if intraabdominal complications have developed. The use of intravenous and oral contrast, if feasible, will help to determine the presence of pancreatic necrosis. The severity of acute pancreatitis has also been classified into 5 grades based upon findings on unenhanced CT, which may be more sensitive than clinical scoring for predicting morbidity and mortality. Ultrasound may as well be used, detecting a large, hypoechoic pancreas in the acute episode and may detect the possible etiologic agent if gallstones are present in the gallbladder. The plain abdominal film with the classic ?sentinel loop? on acute pancreatitis, is less helpful although may help to exclude other conditions like obstruction or bowel perforation.
g.) Esophageal diseases, including Mallory Weiss syndrome, esophageal rupture or perforation, Boerhaave?s syndrome from straining or vomiting, and mediastinitis, may be diagnosed clinically although the use of· chest x-ray, barium swallow and CT scan of the thorax may yield the definitive diagnosis.
h.) Abnormal motility patterns like achalasia and diffuse esophageal spasm, in which the atypical chest pain may be associated with dysphagia, are diagnosed by dynamic barium swallow studies.
2) CARDIOVASCULAR SYSTEM
As stated above, a chest X-ray is the first step in the evaluation of atypical chest pain, giving clues to an underlying cardiac problem like congestive heart failure, cardiomyopathy, pericardial diseases or long-standing valvular diseases.
a.) Ischemic heart disease: the gold standard radiological procedure is the coronary angiography which will evaluate for possible strictures and/or occlusions in the system, as well as delineate the vascular anatomy including anomalies or anatomical variants. The recent application of non-invasive imaging like MRI and CT scans has open a new area of study for the ischemic heart. With MRI, now is not only possible to evaluate the structural composition of the heart, but also to integrate functional studies including myocardium viability thru perfusion techniques. Currently coronary anatomy cannot be accurately mapped, though composition and size of atheromatous plaques can be assessed which may eventually lead to predictions of likelihood of rupture (and hence of MI). ·The use of multidetector CT scans (MDCT) as well permits the detections of cardiomyopathies, ventricular aneurysms and the indirect diagnosis of pulmonary hypertension; the addition of coronary angiography with cardiac gating with this imaging modality can also determine the presence of coronary artery stenosis. Another available test is the electron beam tomography (EBT), which is a highly specialized CT scanner that also permits coronary artery calcium scoring, giving a statistical correlation of plaque burden, although it does not provide much information regarding plaque location or stability to rupture.
b.) Pericarditis: in the acute event when associated with the presence of a pericardial effusion, the detection may be feasible by echocardiogram. CT and MRI may as well indicate its presence. Chest X-ray may suggest it especially with larger effusions.·
c.) Aortic dissection: when suspected by its clinical presentation, a MDCT with IV contrast could not only confirm its presence but also indicate the location which could determine if the approach to repair it will be surgical (thoracotomy) vs ·percutaneous angioplasty. The gold standard, however, is angiography.
3) PULMONARY SYSTEM
a.) Pneumonia: Chest X-ray is readily available, affordable and may even guide to the etiological diagnosis of the pathologic agent, e.g, diffuse bilateral interstitial or alveolar infiltrates in Pneumocystis infection, right upper lobe infiltrates with cavitation on tuberculosis. As always, clinical judgement for antibiotic choice precedes the x-ray findings. This test doesn?t need to be repeated unless the clinical response to treatment is poor or there is underlying evidence of a malignancy or other processes hidden under the pneumonic process. If this case a CT scan of the thorax will permit evaluation not only of the lung parenchyma but also other thoracic structures as well which could be the cause of the atypical chest pain.
b.) Pneumothorax: if clinically suspected a plain chest x-ray may reveal the condition, unless is very small. Other imaging modalities like CT scans could be use in other settings (e.g, chest trauma, pneumomediastinum).
c.) Pulmonary embolism: although a common and in many cases fatal disease, its clinical presentation is variable and nonspecific, making diagnostic testing necessary for confirmation of the diagnosis. There is still debate on weather what radiological modality to use in this setting. As a gold standard, pulmonary angiography is the definitive confirmatory test for suspected pulmonary embolism. It caveat resides on its invasiveness. For this reasons, multidetector CT angiography is a non invasive and still very specific modality to accomplish this purpose, able to demonstrate smaller emboli as well as other conditions in the thoracic wall or lung parenchyma causing the atypical chest pain. Ventilation/perfusion scan, while being the diagnostic choice in the past, is still helpful in those patients that cannot undergo the aforementioned testing, like contrast reactions, renal impairment and other technical factors. Other complementary test to assess the source of the emboli in the lower extremities is a venous Doppler ultrasound, although it may be negative and its absence does not rule out pulmonary embolism; another consideration is the use of a CT venogram protocol, assessing both lungs and lower extremities in the same scanning moment.
d.) Pleural disease: conditions affecting the pleural or the pleural space are multiple and less sensitive by radiological imaging unless a pleural effusion in present. Chest x-ray, CT scan and even MRI may be use in an appropriate clinical context.
4) CONDITIONS ARISING FROM THE CHEST WALL
a.) Breast conditions, including breast cancer, as well are more benign entities like local abscesses, fat necrosis, breast cysts and mastitis may occasionally cause atypical chest pain. In these cases, studies like mammograms, breast ultrasonography or lately MRI may be indicated.
b.) Costochondritis: most likely to be diagnosed clinically, if often a cause of chest pain and radiological workup is rarely necessary or helpful. Muscle tears or sprains of the chest wall also are mostly clinical diagnosis.
c.) Vertebral disc disorders, including discitis, epidural abscesses, spinal cord or nerve root compressions or disc prolapse or herniation are readily detectable with magnetic resonance with very high sensitivity and specificity. Cervical and thoracic spine films may be indicated is there is suspicion of vertebral abnormalities like collapse of fracture as the cause of chest pain.·
d.) Rib cage fractures: these are initially approached with plain chest X-ray. The etiology may comprise fractures secondary to direct trauma, osteopenia or osteoporosis, or even pathological bone fractures, usually from metastatic disease. In the case of osteoporosis, a Dual-Energy X-ray absorption spectrometry (DEXA scan) is the modality of choice to assess the amount of bone loss. If metastatic cancer is a concern, MRI could be use to determine the nature of the fractures.
CONCLUSIONS
This brief review summarizes the radiological approach that should be used in those patients that we frequently encounter with atypical chest pain, in which the diagnosis is often not reached by clinical history, physical examination and basic laboratory data including cardiac biomarkers and 12 lead electrocardiogram. The initial imaging modality that should be obtained is a simple chest X-ray. The rest of the imaging modalities described above should be used on the appropriate clinical context in order to compliment their clinical assessment.
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