Accuracy of Pulmonary Artery Acceleration time derived by Doppler Echocardiography in predicting Pulmonary Artery Pressures.

INTRODUCTION : Two decades ago pulmonary hypertension (PH) was seen as a serious illness with a survival of 2.8 years from its diagnosis. Significant progress has been made in this field in the last ten to fifteen years in the understanding of the pathophysiology and also the treatment of PH. In the past, even though physicians diagnosed PH, treatment of this condition was not rewarding and patients almost always succumbed to the disease. The discovery of prostacyclin by Sir John Vane has since made a revolution in the treatment of PH. PH is a disease that results from reduction in the quantity of blood flowing across the pulmonary circulation, that causes an increase in pulmonary vascular resistance (PVR) and ultimately to right ventricular failure2 Excessive proliferation of the endothelial lining cells of the pulmonary vasculature and reduced apoptosis of the same leads reduction in the luminal cross sectional area of the pulmonary arterial tree. This results in increased pulmonary vascular resistance(PVR). Abnormal and inappropriate vasoconstriction is also implicated in about 20% of patients. Many echocardiographic signs can be present in patients with PH, involving the right ventricle (hypertrophy, dilation, or reduction of systolic function). Though Doppler echocardiography has long been used to estimate systolic pulmonary artery pressure, because of its limited accuracy and reproducibility, invasive cardiac catheterization remains the gold standard for the accurate assessment of right heart hemodynamics. AIM OF THE STUDY : The aim of the study was; 1. To estimate the pulmonary artery systolic pressure by measuring the tricuspid regurgitation peak gradient by Doppler echocardiography in patients with pulmonary hypertension and compare it with invasively derived pulmonary artery systolic pressure obtained by right heart catheterization. 2. To estimate the mean pulmonary artery pressure from pulmonary artery acceleration time measured by Doppler echocardiography in patients with pulmonary hypertension and compare it with invasively derived mean pulmonary artery pressure obtained by right heart catheterization. 3. To find which of the above two methods is more accurate in deriving the pulmonary artery pressures. 4. To test the hypothesis that the pulse Doppler echo derived pulmonary artery acceleration time strongly correlates with invasive pulmonary artery systolic pressure. 5. To compare the strength of correlation between pulmonary artery acceleration time and a. invasive pulmonary artery systolic pressure, b. invasive mean pulmonary artery pressure. 6. To compare the strength of correlation between invasively derived pulmonary artery systolic pressure and a. TRPG derived EPASP, b. PAAT. CONCLUSION : PAAT is easily measurable in patients with pulmonary hypertension and strongly correlates with the values of pulmonary artery systolic pressure and the mean pulmonary artery pressure obtained by right heart catheterisation in a small population of patients with pulmonary hypertension due to a wide spectrum of illness, who underwent Trans Thoracic Echocardiographic (TTE) examination. This is comparable to the strong correlation between the previously well established method of deriving the EPASP from TRVmax and the invasively derived PASP. Adoption of a novel method of determining EPASP from PAAT shall increase significantly the number of patients in whom TTE can be used for the assessment of pulmonary hemodynamics non invasively.