Abstract 17786: Novel Non-invasive Techniques for Assessing Dynamic Pulmonary Vascular Function: Potential Roles for Dobutamine Stress Echocardiography and Postural Single Photon Emission Computed Tomography
Current techniques for assessing pulmonary vascular disease (PVD) are mostly performed under resting conditions. Novel methods aimed at evaluating the pulmonary circulation under dynamic conditions may provide additional pathophysiological insights and allow early detection of PVD.
Aims: We used (1) Dobutamine Stress Echocardiography (DSE) to generate multipoint pressure-flow (mPAP-CO) relationships; and (2) quantitative Single Photon Emission Computed Tomography (qSPECT) to assess changes in regional lung perfusion related to postural shift. We hypothesized that ino-chronotropic stress might alter mPAP-CO relationships and that the normal gravity-related redistribution of lung perfusion may be impaired, in PVD. Methods: (1) Dobutamine infusion (5mcg/kg/min increments) was given to generate mPAP-CO plots. Subjects underwent exercise testing for peak VO2. (2) Regional pulmonary perfusion in supine and upright postures were obtained using qSPECT. A perfusion redistribution index (PRI) was devised to quantify the perfusion shift along the cranial-caudal axis between postures. Results: (1) Sixteen patients with PVD (14 PAH and 2 CTEPH) and 7 healthy controls underwent DSE, with peak dose of 16.6 ± 3.5 mcg/kg/min. The slope of mPAP-CO relationships was 5.1 ± 2.7 mmHg/L/min in PVD subjects and 1.2 ± 0.7 mmHg/L/min in controls (p = 0.001). mPAP-CO slopes correlated significantly with VO2 peak (r2 = -0.34, p = 0.038). (2) Regional lung perfusion was evaluated in 12 PVD subjects (9 PAH and 3 CTEPH) and 10 controls. PVD subjects had markedly reduced PRI (0.44 ± 0.26 vs 3.71 ± 0.66, p = 0.0001)(see Figure). Controls displayed the expected cranial-caudal gradient in lung perfusion (left lung 0.080 cm-1; right lung 0.076 cm-1) which was abolished on supine posture.
Conclusions: Dynamic maneuvres (increasing cardiac output and altered posture) reveal pathophysiologic changes in PVD. These can be measured non-invasively and thus might have a role in assessing early PVD.
- © 2012 by American Heart Association, Inc.