[Pre- and postoperative assessment of hemodynamics in patients with chronic thromboembolic pulmonary hypertension by MR techniques].

PURPOSE: To evaluate the potential of MRI to grade cardiac impairment and pulmonary hypertension in patients with chronic thromboembolic pulmonary hypertension (CTEPH) in comparison with invasive pressure measurements before and after surgery.

MATERIALS AND METHODS: We examined 35 patients with CTEPH before and after pulmonary thromboendarterectomy (PTE). For assessment of hemodynamics, velocity-encoded segmented GE-sequences (pulmonary arteries and ascending aorta) and segmented cine GE-sequences along the short axis of the heart were performed. The analysis comprised calculation of ejection fractions, peak velocities, mean pulmonary arterial flow and vessel diameter. 10 volunteers served as controls. Flow measurements were compared to invasively measured mean pulmonary arterial pressure (MPAP) and vascular resistance (PVR).

RESULTS: Compared to volunteers, CTEPH-patients showed significantly reduced right ventricular ejection fractions (p < 0.001), pulmonary peak velocity (p < 0.001) and significantly increased diameters of the pulmonary arteries (p < 0.001). The flow measurements in the aorta (2713 ml/min) and the pulmonary arteries (2088 ml/min) revealed a large bronchopulmonary shunt. After PTE, there was a significant reduction in vessel diameter (p < 0.001). This was associated with a significant increase in pulmonary peak velocities (p < 0.001). The increase in pulmonary peak velocities correlated with the decrease of PVR (r = 0.5) and MPAP (r = 0.6). The ejection fraction of the right ventricle correlated with PVR (r = 0.6) and MPAP (r = 0.7). The postoperative decrease in MPAP correlated with the increase in right ventricular ejection fraction (r = 0.8). After PTE there was no bronchopulmonary shunt volume. All patients had an inverse motion of the interventricular septum. It returned to normal in 68 % of patients after surgery.

CONCLUSION: Breath-hold MR-techniques enable non-invasive assessment of pulmonary hemodynamics in patients with CTEPH. For postoperative follow-up studies MRI could be considered the modality of choice.