Intravascular Ultrasound Imaging of Pulmonary Arteries: Pulmonary IVUS Guidance in Therapy
Secondary pulmonary hypertension may occur in response to pulmonary parenchymal disease, leftsided heart failure, or mitral valve disease. Intravascular ultrasound has been used to detect abnormalities in vessel wall thickness in pulmonary hypertension secondary to left-sided heart failure, and to determine how this correlates with wall stiffness. Pulmonary IVUS (6F 20 MHz) of vessels from 3 to 7 mm in diameter in patients with chronic congestive heart failure and secondary pulmonary hypertension revealed an increased incidence of plaque in the vessel wall when compared with an age-matched control group, as well as decreased pulsatility and increased vessel stiffness. Although patients with chronic heart failure but normal pulmonary artery pressure had an increased frequency of pulmonary artery plaque by IVUS, they continued to exhibit normal pulmonary artery pulsatility and stiffness. These studies show the usefulness of IVUS in assessing the pulmonary artery dynamics that accompany chronic heart failure. generic yaz
It is unknown whether these IVUS observations can be used to determine reversibility of pulmonary vascular disease with either medical therapy or heart transplantation. Pulmonary IVUS has also been used to detect pulmonary artery invasion by central bronchogenic carcinoma. In this study, vascular invasion by tumor was shown by IVUS, which was surgically confirmed in two cases. Others have shown the IVUS appearance of a localized fibrous histiocytoma within the pulmonary artery. This exciting new application is an example of the ability of pulmonary IVUS to assess the presence and extent of vascular wall invasion in the evaluation of lung tumors.
Guidance in Pulmonary Artery Angioplasty: Pulmonary artery IVUS has also been used to evaluate surgical, pharmacologic, and other mechanical interventions that involve the pulmonary vasculature. Rein et al used a 5F 30 MHz IVUS catheter in three children with Williams syndrome, a congenital disorder, to evaluate the severity and extent of lumen narrowing in the pulmonary artery before and after balloon angioplasty. These pulmonary arteries exhibited regions of severe wall thickening.