PURPOSE: After pulmonary embolism, 1 to 3% of these patients develop a chronic embolism, with elevated pulmonary artery pressure and increased pulmonary vascular resistance (PVR). The continuous elevated pressure leads to the remodeling of the small arteries. The responsiveness to the inhaled nitric oxide could be a marker of the presence of non-remodelated vascular bed.
METHODS: The study includes eleven patients, age 18 to 68, submitted to thromboendarterctomy, between January 2005 and December 2007. All patients, in the pre operative period, were submitted to right cardiac catheterization, with the measurement of the pulmonary pressures, wedge pressure, cardiac output and PVR. Afterwards, they inhaled 20 ppm of nitric oxide for ten minutes, with a new measurement of all variables. Three months after thromboendarterctomy, a new measurement was made, before and after nitric oxide inhalation. We considered a positive test when the medium pulmonary pressure (MPAP) fell to 40 mmHg or less after inhaled oxide nitric (or a drop higher than 10% in MPAP if already 40 mmHg or less).
RESULTS: The statistical analyze used the Student-t test for parametrical data and the Wilcoxon Signed Ranks for non parametrical data. Statistical significance 5%.Only one patient had a positive test before the surgical procedure. After thromboendarterectomy, 8 patients had a positive test (p=0,031). In the pre-operative measurement, 5 had a drop in MPAP more than 20% and 1 had a drop in PVR more than 20% (p<0,05). In the post-operative measurement, 7 had a drop in MPAP more than 20% and 4 had a drop in PVR more than 20% (p< 0,05).
CONCLUSION: After thromboendarterectomy, former occluded vessels are reperfunded and responsiveness to inhaled nitric oxide tends to increase. The lack of responsiveness in 3 patients probably is due to the development of remodeling lesions in the small vessels.
CLINICAL IMPLICATIONS: Patients with responding tests, after thromboendarterectomy, have a larger roll of medical therapies in case of recurrent pulmonary hypertension.
DISCLOSURE: Ricardo Teixeira, No Financial Disclosure Information; No Product/Research Disclosure Information