Intravascular Ultrasound Imaging of Pulmonary Arteries: Pulmonary IVUS to Assess Pathophysiology
The focal pulmonary artery stenoses were balloon dilated, resulting in increases in lumen area. The IVUS findings were associated with an improvement in pulmonary artery hemodynamics.
Assessment of Response to Drug Therapy: Pulmonary artery IVUS has been used to detect different pulmonary vascular area responses to dobu-tamine and nitroglycerin in patients with chronic heart failure undergoing evaluation for orthotopic heart transplantation.’ buy yaz online
In one case study, despite similar calculated measurements of pulmonary vascular resistance changes to these drugs, pulmonary artery IVUS demonstrated vasoconstriction to dobu-tamine but vasodilation to nitroglycerin These responses provided additional information on the pulmonary vascular reactivity in patients with heart failure. A subsequent larger study showed a wide variety of pulmonary artery vascular responses to nitroglycerin in patients with chronic heart failure and pulmonary hypertension that were not predicted by changes in mean pulmonary artery pressure or calculated pulmonary vascular resistance.
Pulmonary IVUS has been useful in showing drug-induced resolution of thromboemboli in patients being treated with thrombolytics for pulmonary emboli. Resolution of thrombus by IVUS has correlated with improvement in pulmonary artery hemodynamics. The time required for resolution of thrombus with local urokinase, however, requires more than 60 min. Since a prolonged IVUS examination involves minimal additional patient discomfort, it is preferred to other imaging modalities, which could be used to monitor thrombus dissolution such as transesophageal echocardiography.
Primary and Secondary Pulmonary Hypertension: In addition to delineating the morphologic abnormalities that accompany primary and secondary pulmonary hypertension, pulmonary IVUS has detected that these patients also have increases in pulmonary vascular stiffness. This is evident on IVUS examination by the marked decrease in vessel pulsatility.