الفهرس 
Pulmonary Vascular AnatomyOnly 14 pages are availabe for public view
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Abstract
Pulmonary hypertension is defined as mean pulmonary artery pressure greater than 25 mm Hg during rest (normal level 10 mm Hg) or greater than 30 mm Hg during exercise (normal level 15 mm Hg) as determined with right heart catheterization (Frazier et al., 2000).
Right-heart catheterization is currently the gold standard method used to measure PH and to grade its severity. Cardiac catheterization, like any invasive procedure, is associated with important risks and complications, such as bleeding, infection, arrhythmias, or cerebrovascular events (Grubstein et al., 2008).
Echocardiography is a key screening method in the diagnostic algorithm because it has special advantages over invasive procedures. It is safe, portable and repeatable. Therefore, echocardiography is more practical for evaluation of PAH at the beginning of the disease and during the follow up (Ginghina et al., 2009).
Computed tomography is commonly performed in patients suspected of having PH or in patients with an underlying diffuse lung disease who may be at risk for PH. In addition, the structure of the pulmonary vasculature at CT has been extensively studied as marker of increased MPAP. In this regard, most investigators have concentrated on dilation of the main pulmonary artery (both in absolute terms and in relation to the size of the ascending aorta) at axial CT as a sign of PH (Devaraj et al., 2008).
Multi-detector CT angiography is now the first line of investigation in the diagnosis of most of pulmonary vascular disorders, it is a relatively available minimally invasive investigation that can now be considered as the first line of investigation in diagnosis of pulmonary embolism with its ability to detect small emboli down to the segmental and sub segmental and it is of value in patients with PH as it show different signs of PH as well as the possible cause (Addis et al., 2001).
Aim of the Work
Because right-sided heart catheterization is an invasive test and this method is not available in the majority of medical centers in our country and also considering its very high cost, there is a need for accurate noninvasive markers that can be appropriately used to diagnose and evaluate PH secondary to respiratory disorders. The present study aimed to evaluate correlation between pulmonary artery pressures measured by Doppler echocardiography and pulmonary arteries` diameters measured by CT angiography in patients with pulmonary hypertension secondary to respiratory disorders, also to evaluate CT pulmonary angiography criteria of pulmonary hypertension secondary to respiratory disorders.
Subjects and Methods
This Study was conducted at Air Forces Hospital and carried out on thirty subjects. Twenty as a study group who have pulmonary hypertension secondary to respiratory disorders, MPAP≥25 mmHg at rest by Doppler echocardiography. And Ten as a control group who have no evidence of pulmonary hypertension and MPAP<25mm Hg at rest by Doppler echocardiography. We also measure SPAP. Then CT pulmonary angiography was done to measure diameter of main pulmonary artery, right main pulmonary artery, left main pulmonary artery and ascending aorta. Also to detect other criteria of pulmonary hypertension secondary to respiratory disorders and its possible complications as embolism, atherosclerotic calcification of the pulmonary arteries and dissecting aneurysm. The CT pulmonary angiography findings in the study group were compared with findings in the control group. Correlation was calculated between Doppler echocardiography findings and CT pulmonary angiography findings in the study group and data was analyzed for any significant correlation between pulmonary artery pressures measured by Doppler echocardiography and pulmonary arteries` diameters measured by CT pulmonary angiography in patients with pulmonary hypertension secondary to respiratory disorders.
Results
Correlation between PAD by CT pulmonary angiography and MPAP by echocardiography in the study group was highly significant, correlation between RT PAD by CT pulmonary angiography and MPAP by echocardiography in the study group was highly significant, correlation between LT PAD by CT pulmonary angiography and MPAP by echocardiography in the study group was significant, correlation between PAD by CT pulmonary angiography and PASP by echocardiography in the study group was highly significant, correlation between RT PAD by CT pulmonary angiography and PASP by echocardiography in the study group was highly significant and correlation between LT PAD by CT pulmonary angiography and PASP by echocardiography in the study group was highly significant. The CT pulmonary angiography diameters of the main pulmonary artery measured have a sensitivity of 100% and specificity of 70% in study group at a cut-off point of 31 mm when compared with control group for a diagnosis of pulmonary hypertension, The CT pulmonary angiography diameters of the right pulmonary artery measured have a sensitivity of 70 % and specificity of 75% in study group at a cut-off point of 16mm when compared with control group for a diagnosis of pulmonary hypertension, The CT pulmonary angiography diameters of the left pulmonary artery measured have a sensitivity of 100 % and specificity of 55% in study group at a cut-off point of 18 mm when compared with control group for a diagnosis of pulmonary hypertension and The ratio of the main pulmonary artery diameter to the diameter of ascending aorta measured has a sensitivity of 100 % and specificity of 80% in study group when compared with control group at a cut-off point of .93 for a diagnosis of pulmonary hypertension.
Conclusion: So, in patients with PHT secondary to respiratory disorders, dilatation of pulmonary arteries was very conspicuous and correlated with the severity of PHT, allowing for a confident diagnosis. Thus CT pulmonary angiography can reliably be used, in addition to echocardiography, for the routine evaluation of patient with pulmonary hypertension secondary to respiratory disorders.
Since echocardiography is not the gold standard method for the diagnosis PHT, a similar study needs to be performed using right heart catheterization instead of echocardiography. Also, further studies needed to assess the utility of CT angiography in the follow up and in patient response to therapy.