Intravascular Ultrasound Imaging of Pulmonary Arteries: Safety of Pulmonary IVUS
Pulmonary vascular stiffness responses are assessed using both pulmonary artery pulse pressure and intravascular ultrasound-derived pulmonary artery area changes in the cardiac cycle. The pulmonary artery stiffness responses to nitroglycerin in patients with secondary pulmonary hypertension are variable and not predicted by the change in mean pulmonary artery pressure or pulmonary vascular resistance. These data suggest that IVUS-derived measurements of pulmonary artery stiffness in pulmonary hypertension provide important information regarding functional abnormalities in the vessel wall that are not obtained with conventional measurements. other
Pulmonary Artery Endothelial Function: Pulmonary artery IVUS has also been used to determine endothelium-dependent responses in patients with chronic heart failure.’ Using IVUS (6F 20 MHz) to observe continuously pulmonary vascular area responses to the endothelium-dependent vasodilator acetylcholine before and after inhibition of endothelium-dependent vasodilation with methylene blue, it has been shown that the endothelial responses of pulmonary arteries in patients with chronic heart failure who maintain normal pulmonary artery pressures inhibit vasoconstriction. These inhibitory effects of the endothelium were defective when pulmonary hypertension developed, suggesting a major role of the pulmonary artery endothelium in attenuating vasoconstriction and thus preventing the development of pulmonary hypertension in treated chronic heart failure. Therefore, pulmonary IVUS can rapidly show in vivo the functional status of the endothelium in pulmonary diseases.
Currently, there have been no reported major complications associated with pulmonary IVUS imaging. It has been safely performed in patients with acute and chronic pulmonary emboli as well as severe primary and secondary pulmonary hypertension. The total number of cases, however, has been relatively small. Therefore, although the procedure appears to be safe with minimal patient discomfort, the actual incidence of potential complications is still unknown.