Intravascular Ultrasound Imaging of Pulmonary Arteries
Intravascular ultrasound imaging of the coronary A artery has become an accepted standard in the evaluation of atherosclerotic lesions.’ It provides more accurate measurements of stenosis areas as well as a qualitative determination of the histologic components of atherosclerotic plaque.” Recently, intravascular ultrasound of the pulmonary artery has been validated as a reliable and rapid method of quantifying proximal and distal pulmonary artery lumen area, pulsatility, and describing vessel wall characteristics. These observations have led to the application of intravascular ultrasound (IVUS) in diagnosing acute and chronic pulmonary thromboembolic disease and evaluating pulmonary artery vessel wall abnormalities in pulmonary artery stenosis, primary pulmonary hypertension, and chronic heart failure. These investigations delineate the potential value of pulmonary vascular ultrasound in determining anatomic and physiologic responses that have previously not been possible in humans in vivo. The purpose of this review is to outline the current conventional methodology of studying the pulmonary vasculature and then to review the advantages that pulmonary vascular ultrasound has been shown to have in evaluating arterial morphology as well as the pathophysiology of common pulmonary vascular diseases. Finally, future applications of pulmonary vascular ultrasound will be briefly discussed. other
Current methods of evaluating pulmonary artery disease in vivo include pulmonary angiography, magnetic resonance (MR) imaging ultrafast computed tomography, transesophageal echocardiography, and intravascular ultrasound. Each technique has certain advantages and disadvantages.
Pulmonary angiography is an established technique for diagnosing pulmonary emboli and other vascular abnormalities of the pulmonary arteries, such as pulmonary artery stenosis, aneurysms, and neoplasms. In chronic pulmonary thromboembolic disease, however, organization of the thrombus may result in no recognizable angiographic abnormalities or nonspecific findings. In addition, pulmonary angiography only outlines the vessel lumen, and it cannot assess abnormalities in the vessel wall or flow abnormalities. This technique is also invasive and has a complication rate, especially in pulmonary hypertension, as high as 4% Most of these complications appear to be related to the injection of contrast medium in patients with pulmonary hypertension.