الفهرس 
IntroductionOnly 14 pages are availabe for public view
 |  | from | 122 |  |  |
| | | from | 122 | | |
Abstract
Pulmonary embolism (PE) is a common disease with a mortality rate of up to 30% .Mortality is usually due to circulatory failure from right heart failure (acute cor-pulmonale). Pressure overload of the right ventricle secondary to acute pulmonary arterial hypertension from PE initially results in right ventricular dysfunction (RVD), which may progress to right ventricular failure and circulatory collapse. Patients with RVD after PE have a higher mortality rate than those with normal right ventricular function even if hemodynamically stable at presentation. Therefore, detection of RVD is useful for risk stratification since these patients may require more aggressive management. In recent years, computed tomography (CT) has emerged as a first-line test for patients with suspected pulmonary embolism in many institutions. Computed tomography not only allows direct visualization of emboli but gives information regarding the status of the right heart by showing the size of the right ventricle and the position of the interventricular septum. CT signs of right ventricular dysfunction includes (a) dilatation of the right ventricle; (b) deviation of the interventricular septum toward the left ventricle; (c) abnormal thickening of the right ventricular wall (ie, a right ventricular wall thickness larger than 0.4 cm); (d) dilatation of the right atrium, inferior vena cava, and coronary sinus; and (e) reflux of contrast material into the inferior vena cava and hepatic veins. (Fig: 22), (Fig: 23) (Fig: 24), (Fig: 25) and (Fig: 26) (Collomb et al, 2003). Several studies have shown that right ventriclular enlargement on CT predicted subsequent admission to the intensive care unit, adverse clinical events ,and early death. Qualitative assessment of the cardiac chambers is a quick and practical means for evaluating of right heart dysfunction on CT. The extent of the pulmonary vascular obstruction graded using the CT clot burden scoring system which is derived from the angiographic scoring systems. The reference standard for right heart dysfunction is obstruction of >30% of the pulmonary vascular bed. CT pulmonary angiography can help identify diseases that have symptoms similar to those of acute pulmonary embolism. Such as pericarditis, acute myocardial infarction, aortic dissection. esophagitis, pneumonia, and pleural disease, including pneumothorax and pleuritis. The diagnosis of PE-induced RV dysfunction by echocardiography based on a wide variety of criteria. The most common is the qualitative echocardiographic assessment of RV wall motion which is judged to be normal or mildly, moderately, or severely hypokinetic. The principal quantitative criterion is the presence of RV dilatation, diagnosed either when RV exceeds LV end-diastolic diameter (RV: LV > 1), or when RV end-diastolic diameter is 30 mm. The presence of pulmonary hypertension, demonstrated either by echocardiography or right-heart catheterization, has also been used as a diagnostic criterion. Diagnostic Criteria for RV Dysfunction by echocardiography: Qualitative: RV hypokinesis (mild, moderate, severe). Quantitative: • RV dilatation. * RV:LV end-diastolic diameter >1. • RV end-diastolic diameter >30 mm. • Pulmonary hypertension. • Pulmonary artery systolic pressure >30 mm Hg. • Tricuspid regurgitant velocity >2.8 m/s. • Pulmonary artery mean pressure >20 mm Hg. In conclusion, qualitative assessment of the cardiac chambers is a quick and practical means for evaluating of right heart dysfunction on CT in patients with acute pulmonary embolism. Computed tomography demonstration of right heart dysfunction compares favorably with echocardiography and correlates with a higher degree of pulmonary vascular obstruction. Because most patients do not undergo echocardiography, chest CT often provides the good opportunity to evaluate for right dysfunction in patients with acute pulmonary embolism.