Chronic Thromboembolic Pulmonary Hypertension

Non-Newtonian Effects of Blood Flow on Hemodynamics in Pulmonary Stenosis: Numerical Simulation

This paper aims to explore the construction of an individualized pulmonary artery stenosis model based on computed tomography (CT) images. The stenosis model is simulated using a porous medium, and the numerical simulation is carried out by computational fluid dynamics (CFD) method to discuss non-Newtonian effects on hemodynamics. The hemodynamic parameters and quantitative pulmonary pressure ratio (QPPR) of the right pulmonary artery stenosis are obtained. The change curves of hemodynamic parameters show that the effects of non-Newtonian fluid are more significant than those of Newtonian fluid. Under the non-Newtonian condition, pressure and velocity drop more and faster when blood flow enters into the stenosis region. There is a high wall shear stress in the stenosis downstream. The margin of error between the QPPR value of the non-Newtonian fluid simulation and the clinical measurement value is not more than 10%. This work provides the evidence that the simulation of non-Newtonian fluid is closer to the reality when a porous medium model is used in a stenosis model. This contributes to assessing the severity of pulmonary stenosis behavior and is essential to guide disease treatment.

Haemodynamic benefit of bridging use of bosentan prior to pulmonary endarterectomy

OBJECTIVES

Some patients present with excessive pulmonary hypertension (PH) prior to pulmonary endarterectomy (PEA) for chronic thromboembolic pulmonary hypertension (CTEPH). This study was performed to evaluate the clinical role of pretreatment before PEA in CTEPH patients.

METHODS

A total of 370 patients with CTEPH undergoing first PEA between 2003 and 2017 were divided into those receiving pretreatment with bosentan (group B: n = 119) and those without targeted pretreatment for PH (group C: n = 251). After selecting patients given bosentan (2-8 months) and using propensity score matching, comparable patient cohorts (n = 23 each) were created from both groups. PEA was performed in the standard manner, and the median number of extracted segments was 14.

RESULTS

There were no significant differences in perioperative demographic characteristics or 30-day mortality (overall 5.7%) between the groups before and after matching. In patients with preoperative pulmonary vascular resistance (PVR) ≥800 dynes s/cm5, a significantly larger decrease in PVR was found in group B (78%) compared to group C (68%) (P = 0.033). There was no significant difference in late survival between the groups after matching. The frequency of residual/persistent PH (mean pulmonary artery pressure >25 mmHg) was lower in group B than in group C, although the difference was not significant (22% vs 39%, respectively, P = 0.200). Advanced age and longer cardiopulmonary bypass time were independent predictors of both 30-day mortality and residual/persistent PH (odds ratio: age, 1.053, 1.013, cardiopulmonary bypass time, 1.065, 1.010, respectively).

CONCLUSIONS

Preoperative treatment of CTEPH patients with bosentan for 2-8 months can improve post-PEA PVR without adverse clinical events in patients with a high preoperative PVR. A temporary bridging regime appears beneficial in selected patients prior to PEA.

Lung Cavities in Chronic Thromboembolic Pulmonary Hypertension

OBJECTIVES

Chronic thromboembolic pulmonary hypertension (CTEPH) is a unique form of pulmonary hypertension (PH) that arises from obstruction of the pulmonary vessels by recanalized thromboembolic material. CTEPH has a wide range of radiologic presentations. Commonly, it presents as main pulmonary artery enlargement, peripheral vascular obstructions, bronchial artery dilations, and mosaic attenuation patterns. Nevertheless, other uncommon presentations have been described, such as lung cavities. These lesions may be solely related to chronic lung parenchyma ischemia but may also be a consequence of concomitant chronic infectious conditions. The objective of this study was to evaluate the different etiologies that cause lung cavities in CTEPH patients.

METHODS

A retrospective data analysis of the medical records of CTEPH patients in a single reference PH center that contained or mentioned lung cavities was conducted between 2013 and 2016.

RESULTS

Seven CTEPH patients with lung cavities were identified. The cavities had different sizes, locations, and wall thicknesses. In two patients, the cavities were attributed to pulmonary infarction; in 5 patients, an infectious etiology was identified.

CONCLUSION

Despite the possibility of being solely associated with chronic lung parenchyma ischemia, most cases of lung cavities in CTEPH patients were associated with chronic granulomatous diseases, reinforcing the need for active investigation of infectious agents in this setting.

Improvements of right ventricular function and hemodynamics after balloon pulmonary angioplasty in patients with chronic thromboembolic pulmonary hypertension

PURPOSE

Right ventricular (RV) function is an important factor in the prognosis of chronic thromboembolic pulmonary hypertension (CTEPH) in patients. In our study, we aimed to evaluate the timing and magnitude of regional RV function before and after balloon pulmonary angioplasty (BPA) using speckle tracking echocardiography (STE) and their relation to clinical and hemodynamic parameters in patients with CTEPH.

MATERIAL AND METHOD

We enrolled 20 CTEPH patients and 19 healthy subjects in our study. Enrolled patients underwent echocardiography, right heart catheterization (RHC), and 6-minute walk distance (6MWD) test at baseline and after the BPA.

RESULTS

In hemodynamic RHC measurements and clinical evaluations, mean pulmonary artery pressure (median: 53.5 mm Hg vs 37.0 mm Hg, P = .001) and pulmonary vascular resistance (median: 12 Wood units [WU] vs 7 WU, P = .001) and pro-brain natriuretic peptide level decreased and 6MWD increased after BPA sessions. There was no statistically significant difference between before and after the BPA sessions in conventional echocardiographic measurements. In STE analysis, the electromechanical delay (EMD) between RV free wall (RVF) and LV lateral wall (LVL) (median: 65 ms vs 47.5 ms, P = .01) and RV peak systolic strain dispersion index (52 ms vs 29 ms, P = .001) were higher in patients with CTEPH than healthy controls before the BPA. Both these parameters decreased significantly after BPA.

CONCLUSION

Chronic thromboembolic pulmonary hypertension was associated with RV electromechanical delay and dispersion based on the STE analysis. Balloon pulmonary angioplasty might have an important impact on the improvement of both RV function and hemodynamics.