Thursday, 28 November 2013

Pulmonary vascular disease – Misdiagnosis and Diagnosis

Pulmonary vascular disease is defined as a condition of blood flow to the lung’s artery is blocked suddenly due to a blood clot somewhere in the body, including pulmonary embolism, chronic thromboembolic disease, pulmonary arterial hypertension, pulmonary veno-occlusive disease, pulmonary arteriovenous malformations, pulmonary edema, etc.
I. Pulmonary embolism
Pulmonary embolism (PE) is defined as a condition of blockage of blood flow due to a blood clot of either in main artery of the lung or somewhere else in the body. In most cases, it is in the deep veins of the legs or pelvic. The disease is a common and affects as many as 500,000 persons annually in the United States.
D. Misdiagnosis and Diagnosis
D.1. Misdiagnosis
1. Congenital absence of the pericardium
There is a report of a case of a 23 year-old-male, who presented to the hospital with complaints of pleuritic chest pain and exertional dyspnea, of a two-week duration. He was physically active and his past history was otherwise insignificant. His chest CT with contrast was interpreted as showing evidence of multiple emboli, predominantly in the left lung, and he was started on a heparin and warfarin therapy. A repeat chest CT with contrast three weeks later showed no significant change from the previous CT scan. Both scans showed that the heart was abnormally rotated to the left side of the chest. An echocardiogram raised the suspicion of congenital absence of the pericardium, with a posteriorly displaced heart. In retrospect, motion artifact on the left lung, attributed to cardiac pulsations and the lack of pericardium, resulted in a CT chest appearance, mimicking findings of pulmonary embolism. The misdiagnosis of pulmonary embolism was attributed to the artifact caused by excessive cardiac motion artifact on the chest CT scan. In non-gated CT angiograms, according to St Francis Medical Center(29).
2. Pulmonary Artery Leiomyosarcoma
There is a report of a 64-year-old woman presented with progressive weakness, fatigue, malaise, and dyspnea, and a marked elevation of pulmonary artery pressure was admitted. She was initially diagnosed with chronic pulmonary thromboembolism and chest computed tomography (CT) scan revealed that lobulated heterogeneous left hilar mass extended to precarinal and subcarinal space. MRI demonstrated a polypoid lesion at trunk with extension to left main pulmonary artery and its first branch(30).
3. Soft tissue sarcomas of the lower limb
Deep venous thrombosis (DVT) or pulmonary embolism (PE) is a rare, but not exceptional presentation of soft tissue sarcomas (STSs). According to the study by the University Hospital Agostino Gemelli, Catholic University of the Sacred Heart School of Medicine, STSs of the lower extremities can rarely present with DVT or PE. This possibility should be considered in the differential diagnosis of painful leg swelling, especially in patients with recurrent or refractory venous thrombosis. When a STS is suspected, MRI should be obtained followed by excisional biopsy of the eventual mass. A delay in diagnosis and treatment of STSs often results in very poor prognosis.Level of evidence(31).
4. Acute anterior myocardial infarction
Pulmonary embolism remains the major malingerer of acute chest disease. There is a report of a case of bilateral pulmonary embolism in a patient of 50 years. The electrocardiogram showed ST elevation in anteroseptal and lateral leads. The diagnosis of acute myocardial infarction was selected and a fibrinolysis achieved. Getting out under beta-blocker therapy, antiplatelet, statin and angiotensin-converting enzyme inhibitors after 10 days hospitalization, the patient was readmitted one month later for a massive pulmonary embolism(32).
5. Acute abdomen
Pulmonary embolisms (PEs) are easily missed both in children and adults because of the varied presentations and subtle clinical findings. There is a report of a series of 2 cases of PE presenting as acute abdomen. Case 1 is a 14-year-old adolescent boy who presented to a pediatric emergency department with abdominal pain, whereas case 2 is a 22-year-old man who presented to the adult emergency department of the same institution with abdominal pain. There was a delay in diagnosis in both cases due to lack of recognition of the unusual presentation. Awareness of the unusual presentations of PE and the risk factors in both adults and children can assist the clinician toward an accurate diagnosis and timely therapeutic intervention(33).
6. Pulmonary artery sarcoma
In a Case analysis and literature review by Chinese Academy of Medical Science and Peking Union Medical College, pulmonary artery Sarcoma can be easily misdiagnosed as pulmonary thromboembolism(34).
D.2. Diagnosis
1. Chest X-ray
In the study to investigate if preliminary chest radiograph (CXR) findings can define the optimum role of lung scintigraphy in subjects investigated for pulmonary embolism (PE), showed that In subjects investigated for PE, an abnormal CXR increases the prevalence of non-diagnostic scintigrams. A normal pre-test CXR is more often associated with a definitive (normal or high probability) scintigram result. The chest radiograph may be useful in deciding the optimum sequence of investigations(35).
2. Ventilation-perfusion (V/Q) scan(Lung scan) and Spiral CT scan
Ventilation-perfusion (V/Q) imaging has been used as the screening test for pulmonary embolism (PE) for many years with diagnostic algorithms developed as a result of the Prospective Investigation of Pulmonary Embolism Diagnosis study. With the increasing availability of spiral (helical) computed tomography (CT) and many studies showing a high degree of accuracy for PE, there is much support for the replacement of V/Q by spiral CT. This article reviews the literature concerning V/Q scanning, spiral (helical) CT, and the future potential for magnetic resonance in the diagnosis of PE(36).
3. Pulmonary angiogram
Traditionally, pulmonary angiography has been the gold standard, but over the years computed tomography pulmonary angiography (CTPA) has replaced it and is now the first line imaging test(37).
4. D-dimer blood test
In the study to validate the use of the Wells clinical decision rule combined with a point of care D-dimer test to safely exclude pulmonary embolism of 598 adults with suspected pulmonary embolism in primary care, found that pulmonary embolism was present in 73 patients (prevalence 12.2%). On the basis of a threshold Wells score of ≤ 4 and a negative qualitative D-dimer test result, 272 of 598 patients were classified as low risk (efficiency 45.5%). Four cases of pulmonary embolism were observed in these 272 patients (false negative rate 1.5%, 95% confidence interval 0.4% to 3.7%). The sensitivity and specificity of this combined diagnostic approach was 94.5% (86.6% to 98.5%) and 51.0% (46.7% to 55.4%)respectively(38).
5. Thorax ultrasound (TUS)
In the multicenter study to determine the accuracy of thorax ultrasound (TUS) in the diagnosis of PE (TUSPE) with data from January 2002 through September 2003 of 352 patients with suspected PE, showed that TUS is a noninvasive method to diagnose peripheral PE. In the absence of CTPA, TUS is a suitable tool to demonstrate a PE at the bedside and in the emergency setting(39).
6. Magnetic resonance imaging (MRI)
In the study to assess the individual and combined usefulness of MRI techniques in cases of acute pulmonary embolism and to compare the usefulness of these techniques with that of 16-MDC, showed that MR perfusion imaging had a sensitivity of 93% for subsegmental pulmonary embolism(40).
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