Computed tomographic pulmonary angiography in the assessment of severity of chronic thromboembolic pulmonary hypertension and right ventricular dysfunction

Diagnostic value of fully automated CT pulmonary angiography in patients with chronic thromboembolic pulmonary hypertension and chronic thromboembolic disease

OBJECTIVES

To evaluate the value of employing artificial intelligence (AI)-assisted CT pulmonary angiography (CTPA) for patients with chronic thromboembolic pulmonary hypertension (CTEPH) and chronic thromboembolic disease (CTED).

METHODS

A single-center, retrospective analysis of 350 sequential patients with right heart catheterization (RHC)-confirmed CTEPH, CTED, and normal controls was conducted. Parameters such as the main pulmonary artery diameter (MPAd), the ratio of MPA to ascending aorta diameter (MPAd/AAd), the ratio of right to left ventricle diameter (RVd/LVd), and the ratio of RV to LV volume (RVv/LVv) were evaluated using automated AI software and compared with manual analysis. The reliability was assessed through an intraclass correlation coefficient (ICC) analysis. The diagnostic accuracy was determined using receiver-operating characteristic (ROC) curves.

RESULTS

Compared to CTED and control groups, CTEPH patients were significantly more likely to have elevated automatic CTPA metrics (all p < 0.001, respectively). Automated MPAd, MPAd/Aad, and RVv/LVv had a strong correlation with mPAP (r = 0.952, 0.904, and 0.815, respectively, all p < 0.001). The automated and manual CTPA analyses showed strong concordance. For the CTEPH and CTED categories, the optimal area under the curve (AU-ROC) reached 0.939 (CI: 0.908-0.969). In the CTEPH and control groups, the best AU-ROC was 0.970 (CI: 0.953-0.988). In the CTED and control groups, the best AU-ROC was 0.782 (CI: 0.724-0.840).

CONCLUSION

Automated AI-driven CTPA analysis provides a dependable approach for evaluating patients with CTEPH, CTED, and normal controls, demonstrating excellent consistency and efficiency.

KEY POINTS

Question Guidelines do not advocate for applying treatment protocols for CTEPH to patients with CTED; early detection of the condition is crucial. Findings Automated CTPA analysis was feasible in 100% of patients with good agreement and would have added information for early detection and identification. Clinical relevance Automated AI-driven CTPA analysis provides a reliable approach demonstrating excellent consistency and efficiency. Additionally, these noninvasive imaging findings may aid in treatment stratification and determining optimal intervention directed by RHC.

Cardiopulmonary remodeling following repetitive acute pulmonary emboli and inhibition of endogenous fibrinolysis in a porcine model

BACKGROUND

The underlying pathophysiology of chronic thromboembolic pulmonary disease (CTEPD) with or without sustained pulmonary hypertension (pH) remains unclear, but repetitive pulmonary emboli (PE) and impaired fibrinolysis are known risk factors. We hypothesized that repetitive PE and inhibition of endogenous fibrinolysis would induce CTEPD with PH (CTEPH).

METHODS

Twenty-four Danish female slaughter pigs of ∼60 kg (4 groups of 6 pigs) were included in the study. Pigs received either autologous PE (PE group), PE plus tranexamic acid (PE + TXA), repetitive PE (day 0, 3, 7, and 10) plus tranexamic acid (REP PE + TXA), or saline infusion (SHAM). Pigs were evaluated at baseline and on day 30 using computed tomography pulmonary angiography (CTPA), invasive hemodynamics, and tissue samples.

RESULTS

CTPA showed increased pulmonary obstruction score on day 30 in REP PE + TXA group compared to remaining groups (0 ± 0 SHAM vs 31 ± 21 PE vs 42 ± 12 PE + TXA vs 69 ± 17 % REP PE + TXA, P = 0.004). Mean pulmonary arterial pressure was higher in REP PE + TXA group on day 30 than remaining groups (12 ± 2 SHAM vs 13 ± 1 PE vs 12 ± 2 PE + TXA vs 16 ± 2 mmHg REP PE + TXA, P = 0.002) yet none of the groups developed PH and right ventricular function was normalized after 30 days. In histological samples, we found chronic thromboembolic lesions with organized fibrotic thrombi, revascularization, and neointima formation, but no microvascular remodeling.

CONCLUSIONS

Autologous repetitive PE and inhibited fibrinolysis caused chronic thrombi without PH in a porcine model. Our findings suggest that a repetitive PE and impaired endogenous fibrinolysis alone are insufficient to develop CTEPH.

TRANSLATIONAL ASPECT

This porcine model using autologous pulmonary emboli presents a realistic large animal model of chronic thromboembolic pulmonary disease particularly suitable to further investigate the vascular remodeling after acute PE. Future research should examine the role of inflammation, endothelial dysfunction and angiogenesis-driven clot resolution to improve understanding of the pathophysiological mechanisms.

Imaging in chronic thromboembolic pulmonary disease: Current practice and advances

Chronic thromboembolic pulmonary disease (CTEPD) with or without pulmonary hypertension (PH) occurs when thromboemboli in pulmonary arteries fail to resolve completely. Pulmonary artery obstructions due to chronic thrombi and secondary microvasculopathy can increase pulmonary arterial pressure and resistance leading to chronic thromboembolic PH (CTEPH). Mechanical interventions and/or PH medications can improve cardiopulmonary haemodynamic, alleviate symptoms, and decrease mortality risk. Imaging is pivotal throughout the CTEPD management journey, spanning diagnosis, treatment planning, and assessing treatment outcome. With just computed tomography (CT) pulmonary angiogram and right heart catheterisation, an experienced multidisciplinary team can determine surgical candidacy in most cases. Dual energy CT, lung subtraction iodine mapping CT, and dynamic contrast-enhanced magnetic resonance imaging (MRI) offer comparable sensitivities with ventilation-perfusion scintigraphy in diagnosing CTEPD. Pulmonary angiogram with digital subtraction angiography although considered the gold standard for assessing thrombi extent and vasculature morphology is now mostly used to assess targets for balloon pulmonary angioplasty. Advancements in CT modalities and innovative MRI metrics offer better insight into CTEPD management but are limited by the availability of technology and expertise. Learning from current artificial intelligence application in medical imaging, there is promise in tapping the wealth of data provided by CTEPD imaging through automating cardiopulmonary and vascular morphology analysis.

Detection and severity quantification of pulmonary embolism with 3D CT data using an automated deep learning-based artificial solution

PURPOSE

The purpose of this study was to propose a deep learning-based approach to detect pulmonary embolism and quantify its severity using the Qanadli score and the right-to-left ventricle diameter (RV/LV) ratio on three-dimensional (3D) computed tomography pulmonary angiography (CTPA) examinations with limited annotations.

MATERIALS AND METHODS

Using a database of 3D CTPA examinations of 1268 patients with image-level annotations, and two other public datasets of CTPA examinations from 91 (CAD-PE) and 35 (FUME-PE) patients with pixel-level annotations, a pipeline consisting of: (i), detecting blood clots; (ii), performing PE-positive versus negative classification; (iii), estimating the Qanadli score; and (iv), predicting RV/LV diameter ratio was followed. The method was evaluated on a test set including 378 patients. The performance of PE classification and severity quantification was quantitatively assessed using an area under the curve (AUC) analysis for PE classification and a coefficient of determination (R²) for the Qanadli score and the RV/LV diameter ratio.

RESULTS

Quantitative evaluation led to an overall AUC of 0.870 (95% confidence interval [CI]: 0.850-0.900) for PE classification task on the training set and an AUC of 0.852 (95% CI: 0.810-0.890) on the test set. Regression analysis yielded R² value of 0.717 (95% CI: 0.668-0.760) and of 0.723 (95% CI: 0.668-0.766) for the Qanadli score and the RV/LV diameter ratio estimation, respectively on the test set.

CONCLUSION

This study shows the feasibility of utilizing AI-based assistance tools in detecting blood clots and estimating PE severity scores with 3D CTPA examinations. This is achieved by leveraging blood clots and cardiac segmentations. Further studies are needed to assess the effectiveness of these tools in clinical practice.

Semi-automatic quantification of mosaic perfusion of lung parenchyma and its correlation with haemodynamic parameters in patients with chronic thromboembolic pulmonary hypertension

AIM

To investigate the feasibility of semiautomatic quantification of mosaic perfusion and the associations between mosaic perfusion on computed tomography (CT; the ratio of hypoperfused parenchyma to the whole lung volume) and haemodynamic parameters through linear regression analysis.

MATERIALS AND METHODS

Fifty-eight consecutive patients (mean age 66 years, 28 females) diagnosed with chronic thromboembolic pulmonary hypertension (CTEPH) in General University Hospital, Prague, in 2021 were evaluated retrospectively and underwent both right heart catheterisation and CT pulmonary angiography. The parameters derived from the CT examinations were correlated with the recorded haemodynamic parameters.

RESULTS

A method was developed for semiautomatic detection of hypoperfused tissue from CT using widely available software and a statistically significant correlation was found between the proportion of hypoperfused parenchyma and the mean pulmonary artery pressure (mPAP; R2 0.22; p<0.01) and pulmonary vascular resistance (PVR; R2 0.09; p<0.05).

CONCLUSIONS

The developed method facilitates the quantification of mosaic perfusion, which is associated with important haemodynamic parameters (mPAP and PVR) in patients with CTEPH.

Cardiovascular metrics on CT pulmonary angiography in patients with pulmonary hypertension - re-evaluation under the updated guidelines of pulmonary hypertension

PURPOSE

To re-assess cardiovascular metrics on computed tomography pulmonary angiography (CTPA) in predicting pulmonary hypertension (PH) under the 2022 ESC/ERS guidelines.

MATERIALS AND METHODS

This observational study retrospectively included 272 patients (female 143, mean age = 54.9 ± 12.5 years old) with suspected PH. 218 patients were grouped to evaluate cardiovascular metrics on CTPA and develop a binary logistic regression model. The other 54 patients were grouped into the validation group to assess the performance of the prediction model under the updated criteria. Based on mean pulmonary artery pressure (mPAP), patients were divided into three groups: group A consisted of patients with mPAP ≤ 20 mmHg, group B included patients with 20 mmHg < mPAP < 25 mmHg, and group C comprised patients with mPAP ≥ 25 mmHg. Cardiovascular metrics among the three groups were compared, and receiver operating characteristic curves (ROCs) were used to evaluate the performance of cardiovascular metrics in predicting mPAP > 20 mmHg.

RESULTS

The main pulmonary arterial diameter (MPAd), MPAd/ascending aorta diameter ratio (MPAd/AAd ratio), and right ventricular free wall thickness (RVFWT) showed significant differences among the three groups (p < 0.05). The area under curve (AUC) of MPAd was larger than MPAd/AAd ratio and RVFWT. A MPAd cutoff value of 30.0 mm has a sensitivity of 83.1% and a specificity of 90.4%. The AUC of the binary logistic regression model (Z =  - 12.98187 + 0.31053 MPAd + 1.04863 RVFWT) was 0.938 ± 0.018. In the validation group, the AUC, sensitivity, specificity, and accuracy of the prediction model were 0.878, 92.7%, 76.9%, and 88.9%, respectively.

CONCLUSION

Under the updated criteria, MPAd with a threshold value of 30.0 mm has better sensitivity and specificity in predicting PH. The binary logistic regression model may improve the diagnostic accuracy.

CRITICAL RELEVANCE STATEMENT

Under the updated criteria, the main pulmonary arterial diameter with a threshold value of 30.0 mm has better sensitivity and specificity in predicting pulmonary hypertension. The binary logistic regression model may improve diagnostic accuracy.

KEY POINTS

• According to 2022 ESC/ERS guidelines, a MPAd cutoff value of 30.0 mm has better sensitivity and specificity in predicting mPAP > 20 mmHg • A binary logistic regression model (Z = - 12.98187 + 0.31053 MPAd + 1.04863 RVFWT) was developed and had a sensitivity, specificity, and accuracy of 92.7%, 76.9%, and 88.9% in predicting mPAP > 20 mmHg. • A binary logistic regression prediction model outperforms MPAd in predicting mPAP > 20 mmHg.

Machine Learning Based on Computed Tomography Pulmonary Angiography in Evaluating Pulmonary Artery Pressure in Patients with Pulmonary Hypertension

BACKGROUND

Right heart catheterization is the gold standard for evaluating hemodynamic parameters of pulmonary circulation, especially pulmonary artery pressure (PAP) for diagnosis of pulmonary hypertension (PH). However, the invasive and costly nature of RHC limits its widespread application in daily practice.

PURPOSE

To develop a fully automatic framework for PAP assessment via machine learning based on computed tomography pulmonary angiography (CTPA).

MATERIALS AND METHODS

A machine learning model was developed to automatically extract morphological features of pulmonary artery and the heart on CTPA cases collected between June 2017 and July 2021 based on a single center experience. Patients with PH received CTPA and RHC examinations within 1 week. The eight substructures of pulmonary artery and heart were automatically segmented through our proposed segmentation framework. Eighty percent of patients were used for the training data set and twenty percent for the independent testing data set. PAP parameters, including mPAP, sPAP, dPAP, and TPR, were defined as ground-truth. A regression model was built to predict PAP parameters and a classification model to separate patients through mPAP and sPAP with cut-off values of 40 mm Hg and 55 mm Hg in PH patients, respectively. The performances of the regression model and the classification model were evaluated by analyzing the intraclass correlation coefficient (ICC) and the area under the receiver operating characteristic curve (AUC).

RESULTS

Study participants included 55 patients with PH (men 13; age 47.75 ± 14.87 years). The average dice score for segmentation increased from 87.3% ± 2.9 to 88.2% ± 2.9 through proposed segmentation framework. After features extraction, some of the AI automatic extractions (AAd, RVd, LAd, and RPAd) achieved good consistency with the manual measurements. The differences between them were not statistically significant (t = 1.222, p = 0.227; t = -0.347, p = 0.730; t = 0.484, p = 0.630; t = -0.320, p = 0.750, respectively). The Spearman test was used to find key features which are highly correlated with PAP parameters. Correlations between pulmonary artery pressure and CTPA features show a high correlation between mPAP and LAd, LVd, LAa (r = 0.333, p = 0.012; r = -0.400, p = 0.002; r = -0.208, p = 0.123; r = -0.470, p = 0.000; respectively). The ICC between the output of the regression model and the ground-truth from RHC of mPAP, sPAP, and dPAP were 0.934, 0.903, and 0.981, respectively. The AUC of the receiver operating characteristic curve of the classification model of mPAP and sPAP were 0.911 and 0.833.

CONCLUSIONS

The proposed machine learning framework on CTPA enables accurate segmentation of pulmonary artery and heart and automatic assessment of the PAP parameters and has the ability to accurately distinguish different PH patients with mPAP and sPAP. Results of this study may provide additional risk stratification indicators in the future with non-invasive CTPA data.

Right-to-left ventricle ratio determined by machine learning algorithms on CT pulmonary angiography images predicts prolonged ICU length of stay in operated chronic thromboembolic pulmonary hypertension

OBJECTIVE

Right-to-left ventricle diameter ratio (dRV/dLV) on CT pulmonary angiography (CTPA) is a predictor of outcomes in non-operated chronic thromboembolic pulmonary hypertension (CTEPH) patients. The purpose of this study is to evaluate the performance of a novel machine learning (ML) algorithm for dRV/dLV measurement in operated CTEPH patients and its association with post-operative outcomes.

METHODS

This retrospective study reviewed consecutive CTEPH patients who underwent pulmonary endarterectomy between 2013 and 2017. ML calculated dRV/dLV on pre-operative CTPA and compared with manual measures. Associations of dRV/dLV with patient characteristics and post-operative outcomes were evaluated including intensive care (ICU) and hospital length of stay (LOS) using multivariable linear regression analysis. Prolonged LOS was defined as greater than median.

RESULTS

ML segmented the ventricles in 99/125 (79%) patients. The most common cause of failure was misidentification of the moderator band as the interventricular septum (7.9%). Mean dRV/dLV by ML was 1.4 ± 0.4 and strongly correlated with manual measures (r = 0.9-0.96 p < 0.0001). dRV/dLV was moderately correlated with measures of pulmonary hypertension on right heart catheterization and RV dilatation on echocardiogram (r = 0.5-0.6, p < 0.0001). dRV/dLV ≥ 1.2 was associated with proximal Jamieson type disease (p = 0.032), longer cardiopulmonary bypass (p = 0.037), aortic cross-clamp (p = 0.022) and circulatory arrest (p < 0.001) at surgery and dRV/dLV ≥ 1.6 with post-operative ECMO (p = 0.006). dRV/dLV was independently associated with prolonged ICU LOS (OR = 3.79, 95% CI 1.1-13.06, p = 0.035).

CONCLUSION

dRV/dLV was associated with CTEPH severity and independently associated with prolonged ICU LOS. This CT parameter may therefore assist in perioperative planning. Further refinement of the ML algorithm or CTPA technique is required to avoid errors in ventricular segmentation.

ADVANCES IN KNOWLEDGE

Automated right-to-left ventricle ratio measurement by machine learning is feasible and is independently associated with outcome after pulmonary endarterectomy.

Clot burden of acute pulmonary thromboembolism: comparison of two deep learning algorithms, Qanadli score, and Mastora score

BACKGROUND

The deep learning convolution neural network (DL-CNN) benefits evaluating clot burden of acute pulmonary thromboembolism (APE). Our objective was to compare the performance of the deep learning convolution neural network trained by the fine-tuning [DL-CNN (ft)] and the deep learning convolution neural network trained from the scratch [DL-CNN (fs)] in the quantitative assessment of APE.

METHODS

We included the data of 680 cases for training DL-CNN by DL-CNN (ft) and DL-CNN (fs), then retrospectively included 410 patients (137 patients with APE, 203 males, mean age 60.3±11.4 years) for testing the models. The distribution and volume of clots were respectively assessed by DL-CNN(ft) and DL-CNN(fs), and sensitivity, specificity, and area under the curve (AUC) were used to evaluate their performances in detecting clots on a per-patient and clot level. Radiologists evaluated the distribution of clots, Qanadli score, and Mastora score and right ventricular metrics, and the correlation of clot volumes with right ventricular metrics were analyzed with Spearman correlation analysis.

RESULTS

On a per-patient level, the two DL-CNN models had high sensitivities and moderate specificities [DL-CNN (ft): 100% and 77.29%; DL-CNN (fs): 100% and 75.82%], and their AUCs were comparable (Z=0.30, P=0.38). On a clot level, DL-CNN (ft) and DL-CNN (fs) sensitivities and specificities in detecting central clots were 99.06% and 72.61%, and 100% and 70.63%, respectively. DL-CNN (ft) sensitivities and specificities in detecting peripheral clots were mostly higher than those of DL-CNN (fs), and their AUCs were comparable. Clot volumes measured with the two models were similar (U=85094.500, P=0.741), and significantly correlated with Qanadli scores [DL-CNN(ft) r=0.825, P<0.001, DL-CNN(fs) r=0.827, P<0.001] and Mastora scores [DL-CNN(ft) r=0.859, P<0.001, DL-CNN(fs) r=0.864, P<0.001]. Clot volumes were also correlated with right ventricular metrics. Clot burdens were increased in the low-risk, moderate-risk, and high-risk patients. Binary logistic regression revealed that only the ratio of right ventricular area/left ventricular area (RVa/LVa) was an independent predictor of in-hospital death (odds ratio 6.73; 95% CI, 2.7-18.12, P<0.001).

CONCLUSIONS

Both DL-CNN (ft) and DL-CNN (fs) have high sensitivities and moderate specificities in detecting clots associated with APE, and their performances are comparable. While clot burdens quantitatively calculated by the two DL-CNN models are correlated with right ventricular function and risk stratification, RVa/LVa is an independent prognostic factor of in-hospital death in patients with APE.

Clinical importance of the distribution of pulmonary artery embolism in acute pulmonary embolism

OBJECTIVE

To explore the clinical importance of the distribution of pulmonary artery embolism in acute pulmonary embolism (APE).

METHODS

Sixty-four patients with APE were classified into mixed-type and distal-type pulmonary embolism groups. Their right ventricular systolic pressure (RVSP) and disease duration were recorded, and the diameter of their right ventricles was measured by ultrasound. The computed tomography angiographic clot load was determined as a Mastora score.

RESULTS

Patients with distal-type pulmonary embolisms had significantly lower RVSPs (44.92 ± 17.04 vs 55.69 ± 17.66 mmHg), and significantly smaller right ventricular diameters (21.08 ± 3.06 vs 23.37 ± 3.48 mm) than those with mixed-type pulmonary embolisms. Additionally, disease duration was significantly longer in patients with distal-type pulmonary embolisms (14.33 ± 11.57 vs 8.10 ± 7.10 days), and they had significantly lower Mastora scores (20.91% ± 18.92% vs 43.96% ± 18.30%) than patients with mixed-type pulmonary embolisms. After treatment, RVSPs decreased significantly in patients with both distal-type and mixed-type pulmonary embolisms. Right ventricle diameters also decreased significantly in patients with mixed-type pulmonary embolisms after treatment.

CONCLUSION

Patients with mixed-type pulmonary embolisms are significantly more susceptible to pulmonary hypertension, enlarged right ventricular diameters, and shorter durations of disease than those with distal-type pulmonary embolisms. The distribution of pulmonary artery embolism in APE can provide a clinical reference.

Treatment effect prediction using CT after balloon pulmonary angioplasty in chronic thromboembolic pulmonary hypertension

OBJECTIVE

To evaluate whether the change in computed tomography pulmonary angiography (CTPA) metrics after balloon pulmonary angioplasty (BPA) can predict treatment effect in chronic thromboembolic pulmonary hypertension (CTEPH) patients.

METHODS

This study included 82 CTEPH patients who underwent both CTPA and right heart catheterization (RHC) before and at the scheduled time of 6 months after BPA. The diameters of the main pulmonary artery (dPA), ascending aorta (dAA), right atrium (dRA), right ventricular free wall thickness (dRVW), and right and left ventricles (dRV, dLV) were measured on CTPA. The correlation of the New York Heart Association functional class (NYHA FC), 6-minute walking distance (6MWD), brain natriuretic peptide (BNP) level, and calculated CT metrics with a decrease in mean pulmonary artery pressure (ΔmPAP) using RHC (used as the reference for BPA effect) was investigated. Using multiple regression analysis, independent variables were also identified.

RESULTS

In univariate analysis, clinical indicators (NYHA FC, 6MWD, and BNP level) improved significantly after BPA and were significantly correlated with ΔmPAP (p < 0.01). In the univariate analysis of CTPA parameters, dPA, dRA, dPA/dAA ratio, dRVW, and dRV/dLV ratio decreased significantly and were significantly correlated with ΔmPAP (p < 0.01). Multivariate analysis demonstrated that decreased dPA (p = 0.001) and decreased dRA (p = 0.039) on CTPA were independent predictive factors of ΔmPAP.

CONCLUSIONS

Decreased dPA and dRA on CTPA could predict a decrease in mPAP after BPA, thus potentially eliminating unnecessary invasive catheterization.

KEY POINTS

• The reduction in mean pulmonary artery pressure after balloon pulmonary angioplasty in CTEPH patients was significantly correlated with the clinical indices improvement and CTPA parameter decrease. • The decreased diameter of the main pulmonary artery and the decreased diameter of the right atrium on CTPA were independent predictors of mean pulmonary artery pressure reduction.

Radiological differences between chronic thromboembolic pulmonary disease (CTEPD) and chronic thromboembolic pulmonary hypertension (CTEPH)

OBJECTIVES

The aim of this study was to describe the radiological features of chronic thromboembolic pulmonary disease (CTEPD), not yet systematically described in the literature. Furthermore, we compared vascular scores between CTEPD and chronic thromboembolic pulmonary hypertension (CTEPH) patients, trying to explain why pulmonary hypertension does not develop at rest in CTEPD patients.

METHODS

Eighty-five patients (40 CTEPD, 45 CTEPH) referred to our centre for pulmonary endarterectomy underwent dual-energy computed tomography pulmonary angiography (DE-CTPA) with iodine perfusion maps; other 6 CTEPD patients underwent single-source CTPA. CT scans were reviewed independently by an experienced cardiothoracic radiologist and a radiology resident to evaluate scores of vascular obstruction, hypoperfusion and mosaic attenuation, signs of pulmonary hypertension and other CT features typical of CTEPH.

RESULTS

Vascular obstruction burden was similar in the two groups (p = 0.073), but CTEPD patients have a smaller extension of perfusion defects in the iodine map (p = 0.009) and a smaller number of these patients had mosaic attenuation (p < 0.001) than CTEPH patients, suggesting the absence of microvascular disease. Furthermore, as expected, the two groups were significantly different considering the indirect signs of pulmonary hypertension (p < 0.001).

CONCLUSIONS

CTEPD and CTEPH patients have significantly different radiological characteristics, in terms of signs of pulmonary hypertension, mosaic attenuation and iodine map perfusion extension. Importantly, our results suggest that the absence of peripheral microvascular disease, even in presence of an important thrombotic burden, might be the reason for the absence of pulmonary hypertension in CTEPD.

KEY POINTS

• CTEPD and CTEPH patients have significantly different radiological characteristics. • The absence of peripheral microvascular disease might be the reason for the absence of pulmonary hypertension in CTEPD.

Clinical outcome and survival in 30 pulmonary hypertension patients with high severity indices and advanced functional class

BACKGROUND

Pulmonary hypertension (PH) is an idiopathic or secondary disorder associated with many systemic illnesses. Long-term survival in PH depends on the severity and functional class. Several new drugs are now available to treat PH, but their impact on clinical outcome and survival are not well established.

OBJECTIVES

Evaluate severity parameters and the impact of current recommended therapy on survival in PH.

DESIGN

Cross-sectional.

SETTINGS

Tertiary care center.

PATIENTS AND METHODS

The study included adult patients who had undergone right heart catheterization since 2012 and were diagnosed with pulmonary hypertension. Survival was recorded after 6 years, at the end of the study. Nine severity variables for PH were assessed including right ventricular size by echocardiogram and pulmonary artery diameter (PA diameter) and the ratio of pulmonary artery diameter to ascending aorta diameter (PA/Ao ratio) by CT.

MAIN OUTCOME MEASURES

Evaluation of severity parameters.

SAMPLE SIZE

30 patients.

RESULTS

Twenty-five patients were positive for 8/9 severity parameters. Eight of 30 (26.6%) patients died. In nonsurvivors, right ventricular size was increased by 25% ( P=.427), pulmonary vascular resistance increased by 29.4% in nonsurvivors ( P=.302), the 6-minute walk distance decreased by 21% ( P=.875), median brain natriuretic peptide increased by 96% ( P=.890), median GGT and alkaline phosphatase were 3 times higher in nonsurvivors ( P=.893 and P=.047, respectively) and PA/Ao was nonsignificantly decreased in nonsurvivors ( P=.373), Survival was decreased by a median of 2.3 years in nonsurvivors.

CONCLUSION

Our study identified a subgroup of PH patients with NYHA functional class III and above with worsening severity indicators who were labeled as a high-risk group. These patients showed continuous deterioration in their clinical status despite escalation of therapy with current guidelines. We recommend these high-risk group patients be referred for early lung transplantation.

LIMITATIONS

Low sample size and only a single center. Needs confirmation with a larger multicenter trial.

CONFLICT OF INTEREST

None.

The Value of Bedside Echocardiogram in the Setting of Acute and Chronic Pulmonary Embolism

Echocardiography is valuable in the evaluation and risk stratification of patients with acute and chronic pulmonary embolism (PE). Patients with acute PE who have echocardiographic evidence of right ventricular dilatation and/or right ventricular dysfunction have a worse prognosis. A minority of patients with acute PE can develop chronic thromboembolic pulmonary hypertension. Patients with chronic thromboembolic pulmonary hypertension often have echocardiographic evidence of elevated pulmonary arterial pressures, right ventricular hypertrophy, right ventricular dysfunction, and/or left ventricular impaired relaxation.

Non-invasive Multimodality Cardiovascular Imaging of the Right Heart and Pulmonary Circulation in Pulmonary Hypertension

Pulmonary hypertension (PH) is defined as resting mean pulmonary arterial pressure (mPAP) ≥25 millimeters of mercury (mmHg) via right heart (RH) catheterization (RHC), where increased afterload in the pulmonary arterial vasculature leads to alterations in RH structure and function. Mortality rates have remained high despite therapy, however non-invasive imaging holds the potential to expedite diagnosis and lead to earlier initiation of treatment, with the hope of improving prognosis. While historically the right ventricle (RV) had been considered a passive chamber with minimal role in the overall function of the heart, in recent years in the evaluation of PH and RH failure the anatomical and functional assessment of the RV has received increased attention regarding its performance and its relationship to other structures in the RH-pulmonary circulation. Today, the RV is the key determinant of patient survival. This review provides an overview and summary of non-invasive imaging methods to assess RV structure, function, flow, and tissue characterization in the setting of imaging's contribution to the diagnostic, severity stratification, prognostic risk, response of treatment management, and disease surveillance implications of PH's impact on RH dysfunction and clinical RH failure.

Evaluation of the CT imaging findings in patients newly diagnosed with chronic thromboembolic pulmonary hypertension

PURPOSE

The aim of this study was to evaluate the vascular and parenchymal CT imaging findings, including vessel and cardiac chamber diameter measurements, in patients newly diagnosed with chronic thromboembolic pulmonary hypertension (CTEPH). The CT imaging findings were correlated with hemodynamic measurements and patient outcome.

METHODS

Vascular and parenchymal CT findings were assessed on retrospectively ECG-gated MDCT angiography scans in 76 patients newly diagnosed with CTEPH. The diameters of the right and left ventricle (dRV, dLV), the right and left atrium (dRA, dLA), the ascending aorta (dAA), the right and left pulmonary arteries (drPA, dlPA), and the main pulmonary artery (dPA) were measured on axial CT scans. The CT imaging findings were correlated with demographic and hemodynamic data and adverse patient outcome due to right heart failure (RHF).

RESULTS

The majority of patients showed chronic PE, mosaic perfusion, disparity in segmental vessel size, parenchymal densities, bronchial dilatation, and bronchial collaterals in CT. Mean pulmonary artery pressure (mPAP) was not significantly different in patients with and those without chronic PE, mosaic perfusion, disparity in segmental vessel size, parenchymal densities, bronchial dilatation, and bronchial collaterals. Mean PAP showed significant correlations with the CT metrics of dRV/dLV ratio, dRA, dRV, dPA and dPA/dAA ratio, but no correlation with the central thrombi score. By backward linear regression, the dPA/dAA ratio independently correlated with mPAP. Patients who died of RHF tended to have a higher frequency of exclusively chronic peripheral PE and greater dRV/dLV ratios on presenting CT scans compared with survivors.

CONCLUSION

The majority of patients newly diagnosed with CTEPH show vascular signs of chronic PE, mosaic perfusion, parenchymal densities, disparity in segmental vessel size, bronchial dilatation, and bronchial collaterals on presenting CT scans. Particularly CTEPH patients with exclusively chronic peripheral PE and increased dRV/dLV ratios seem to be at risk of adverse outcome due to RHF.

Diagnostic Evaluation of Chronic Thromboembolic Pulmonary Hypertension

Pulmonary hypertension is defined by a mean pulmonary artery pressure greater than 25 mm Hg. Chronic thromboembolic pulmonary hypertension (CTEPH) is defined as pulmonary hypertension in the presence of an organized thrombus within the pulmonary vascular bed that persists at least 3 months after the onset of anticoagulant therapy. Because CTEPH is potentially curable by surgical endarterectomy, correct identification of patients with this form of pulmonary hypertension and an accurate assessment of surgical candidacy are essential to provide optimal care. Patients most commonly present with symptoms of exertional dyspnea and otherwise unexplained decline in exercise capacity. Atypical chest pain, a nonproductive cough, and episodic hemoptysis are observed less frequently. With more advanced disease, patients often develop symptoms suggestive of right ventricular compromise. Physical examination findings are minimal early in the course of this disease, but as pulmonary hypertension progresses, may include nonspecific finding of right ventricular failure, such as a tricuspid regurgitation murmur, pedal edema, and jugular venous distention. Chest radiographs may suggest pulmonary hypertension, but are neither sensitive nor specific for the diagnosis. Radioisotopic ventilation-perfusion scanning is sensitive for detecting CTEPH, making it a valuable screening study. Conventional catheter-based pulmonary angiography retains an important role in establishing the presence and extent of chronic thromboembolic disease. However, computed tomographic and magnetic resonance imaging are playing a growing diagnostic role. Innovative technologies such as dual-energy computed tomography, dynamic contrast-enhanced magnetic resonance imaging, and optical coherence tomography show promise for contributing diagnostic information and assisting in the preoperative characterization of patients with CTEPH.

A new CT-score as index of hemodynamic changes in patients with chronic thromboembolic pulmonary hypertension

PURPOSE

The aim of this study was to retrospectively assess the relationship between radiological and hemodynamic parameters in patients with chronic thromboembolic pulmonary hypertension (CTEPH). We introduced a new CT-score to evaluate hemodynamic changes, only employing CT-pulmonary angiography (CTPA).

MATERIALS AND METHODS

145 patients affected by CTEPH underwent hemodynamic and CTPA evaluation. Among these 145 patients, 69 underwent pulmonary endarterectomy (PEA) and performed a CTPA evaluation even after surgery. Hemodynamic assessment considered the values of mean pulmonary artery pressure (mPAP) and pulmonary vascular resistance (PVR), obtained through right heart catheterization (RHC). Radiological evaluation included CTPA signs of pulmonary hypertension.

RESULTS

A highly significant statistical correlation was observed between the new CT-score and both mPAP and PVR (p < 0.000) in the whole sample and also in the subgroup who underwent PEA. In addition, mPAP and PVR showed an important association with the severity of mosaic perfusion (p < 0.000). mPAP also correlated with main pulmonary artery diameter (p < 0.01); a significant association was found in both between PVR and tricuspid regurgitation(p < 0.000) and with PVR and presence of unilateral or bilateral pulmonary thromboembolic occlusion (p < 0.05).

CONCLUSION

Our results confirm the diagnostic role of CTPA in evaluating patients with CTEPH and in addition open a new horizon in assessing hemodynamic changes in patients with CTEPH, only employing a CTPA, especially when RHC is contraindicated or not possible.

Chronic Embolic Pulmonary Hypertension Caused by Pulmonary Embolism and Vascular Endothelial Growth Factor Inhibition

Our understanding of the pathophysiological basis of chronic thromboembolic pulmonary hypertension (CTEPH) will be accelerated by an animal model that replicates the phenotype of human CTEPH. Sprague-Dawley rats were administered a combination of a single dose each of plastic microspheres and vascular endothelial growth factor receptor antagonist in polystyrene microspheres (PE) + tyrosine kinase inhibitor SU5416 (SU) group. Shams received volume-matched saline; PE and SU groups received only microspheres or SU5416, respectively. PE + SU rats exhibited sustained pulmonary hypertension (62 ± 13 and 53 ± 14 mmHg at 3 and 6 weeks, respectively) with reduction of the ventriculoarterial coupling in vivo coincident with a large decrement in peak rate of oxygen consumption during aerobic exercise, respectively. PE + SU produced right ventricular hypokinesis, dilation, and hypertrophy observed on echocardiography, and 40% reduction in right ventricular contractile function in isolated perfused hearts. High-resolution computed tomographic pulmonary angiography and Ki-67 immunohistochemistry revealed abundant lung neovascularization and cellular proliferation in PE that was distinctly absent in the PE + SU group. We present a novel rodent model to reproduce much of the known phenotype of CTEPH, including the pivotal pathophysiological role of impaired vascular endothelial growth factor-dependent vascular remodeling. This model may reveal a better pathophysiological understanding of how PE transitions to CTEPH in human treatments.

Computed Tomographic Pulmonary Angiographic Findings Can Predict Short-Term Mortality of Saddle Pulmonary Embolism: A Retrospective Multicenter Study

OBJECTIVE

In patients with saddle pulmonary embolism (PE), the correlation between computed tomographic pulmonary angiographic (CTPA) findings and short-term outcome remains unclear. The purpose is to determine if CTPA findings predict 1-month mortality of patients with saddle PE.

METHODS

This is a multicenter, retrospective study of saddle PE. Computed tomographic pulmonary angiographic findings of 115 consecutive patients (male-to-female ratio, 65:50; mean age, 64.3 ± 16.3 years) with saddle PE were evaluated. One-month mortality after diagnosis was the primary end point.

RESULTS

Twenty-four patients died within 1 month. Among CTPA findings, quantitative parameters including right/left ventricular area ratios (RVa/LVa), right/left atrial diameter ratios, Cobb angle, and Mastora score were significantly enlarged in survivors. Also, qualitative findings including contrast agent reflux into the azygos vein and pericardial effusion were significantly different between survivors and nonsurvivors. Areas under the curve on receiver operating characteristic curves revealed the cutoff values for predicting early mortality of saddle PE using right/left atrial diameter ratios, RVa/LVa, Mastora score, and Cobb angle, respectively, were 2.15, 2.00, 69%, and 58°. Logistic regression analysis suggested that both RVa/LVa (odds ratio, 5.100; P = 0.0004) and Cobb angle (odds ratio, 1.596; P = 0.0321) were independent predictors of early mortality. The combination of RVa/LVa and Cobb angle increased the area under the curve to 0.882, but the difference did not reach significance compared with RVa/LVa or Cobb angle, alone (P > 0.05).

CONCLUSION

In patients with saddle PE, RVa/LVa and Cobb angle seem valuable in predicting short-term mortality.

Saddle Pulmonary Embolism: Laboratory and Computed Tomographic Pulmonary Angiographic Findings to Predict Short-term Mortality

BACKGROUND

Saddle pulmonary embolism (SPE) is rare type of acute pulmonary embolism and there is debate about its treatment and prognosis. Our aim is to assess laboratory and computed tomographic pulmonary angiographic (CTPA) findings to predict short-term mortality in patients with SPE.

METHODS

This was a five-centre, retrospective study. The clinical information, laboratory and CTPA findings of 88 consecutive patients with SPE were collected. One-month mortality after diagnosis of SPE was the primary end-point. The correlation of laboratory and CTPA findings with one-month mortality was analysed with area under curve (AUC) of receiver operating characteristic (ROC) curves and logistic regression analysis.

RESULTS

Eighteen patients with SPE died within one month. Receiver operating characteristic curves revealed that the cutoff values for the right and left atrial diameter ratio, the right ventricular area and left ventricular area ratio (RVa/LVa ratio), Mastora score, septal angle, N-terminal pro-brain natriuretic peptide and cardiac troponin I (cTnI) for detecting early mortality were 2.15, 2.13, 69%, 57°, 3036 pg/mL and 0.18ng/mL, respectively. Using logistic regression analysis of laboratory and CTPA findings with regard to one-month mortality of SPE, RVa/LVa ratio and cTnI were shown to be independently associated with early death. A combination of cTnI and RVa/LVa ratio revealed an increase in the AUC value, but the difference did not reach significance compared with RVa/LVa or cTnI, alone (P>0.05).

CONCLUSION

In patients with SPE, both the RVa/LVa ratio on CTPA and cTnI appear valuable for the prediction of short-term mortality.

Advances in the management of chronic thromboembolic pulmonary hypertension

Chronic thromboembolic pulmonary hypertension (CTEPH), a potentially curable form of pulmonary hypertension with pulmonary thromboendarterectomy surgery, has been the focus of significant medical advances. In addition to new imaging modalities that are now used to help recognize and diagnose CTEPH, additional treatment options have emerged for inoperable cases. These include a newly approved medical therapy for inoperable disease or persistent/recurrent CTEPH as well as percutaneous balloon angioplasty of the pulmonary arteries. In this article, we summarize these recent advances in the field and review the related literature.

Significance of main pulmonary artery dilation on imaging studies

Proper and early identification of patients who harbor serious occult illness is the first step in developing a disease-management strategy. Identification of illnesses through the use of noninvasive techniques provides assurance of patient safety and is ideal. PA dilation is easily measured noninvasively and is due to a variety of conditions, including pulmonary hypertension (PH). The clinician should be able to thoroughly assess the significance of PA dilation in each individual patient. This involves knowledge of the ability of PA dilation to accurately predict PH, understand the wide differential diagnosis of causes of PA dilation, and reverse its life-threatening complications. We found that although PA dilation is suggestive of PH, data remain inconclusive regarding its ability to accurately predict PH. At this point, data are insufficient to place PA dilation into a PH risk-score equation. Here we review the causes and complications of PA dilation, define normal and abnormal PA measurements, and summarize the data linking its association to PH, while suggesting an algorithm designed to assist clinicians in patient work-up after recognizing PA dilation.

Non-invasive evaluation of hemodynamics in pulmonary hypertension by a Septal angle measured by computed tomography pulmonary angiography: Comparison with right-heart catheterization and association with N-terminal pro-B-type natriuretic peptide

The septal angle, an angle between the interventricular septum and the line connecting the sternum midpoint and thoracic vertebral spinous process, as measured by computed tomographic pulmonary angiography (CTPA), has been observed to be increased in patients with pulmonary hypertension (PH), but its meaning remains unclear. The aim of this study was to investigate the potential role of the septal angle in evaluating hemodynamics and its association with N-terminal pro-B-type natriuretic peptide (NT-proBNP) in patients with PH. Patients with PH (n=106), including 76 with chronic thromboembolic pulmonary hypertension (CTEPH) and 30 with pulmonary artery hypertension (PAH), were retrospectively reviewed. The patients underwent CTPA prior to right-heart catheterization. The septal angle was measured on transversal CTPA images. Hemodynamic parameters were evaluated by right-heart catheterization. The level of plasma NT-proBNP was measured by enzyme-linked sandwich immunoassay. The septal angle had a moderate correlation with cardiac output (CO; r=−0.535, P=0.000) and a high correlation with pulmonary vascular resistance (PVR; r=0.642, P=0.000). The mean level of NT-proBNP in PH was 1,716.09±1,498.30 pg/ml, which correlated with the septal angle (r=0.693, P=0.000). In a stepwise forward regression analysis, the Septal angle was entered into the final equation for predicting PVR, leading to the following equation: PVR = 28.256 × Septal angle - 728.72. In CTEPH, the Septal angle strongly correlated with NT-proBNP (r=0.668, P=0.000) and PVR (r=0.676, P=0.000). In PAH, the Septal angle strongly correlated with NT-proBNP (r=0.616, P=0.003) and PVR (r=0.623, P=0.000). The CTPA-derived Septal angle is a superior predictor for evaluating and monitoring the level of NT-proBNP and PVR in patients with PH.

Increased pulmonary artery diameter on chest computed tomography can predict borderline pulmonary hypertension

Pulmonary hypertension (PH) often leads to dilatation of the pulmonary artery (PA), which can be measured on chest computed tomography (CT). While the predictive capability of PA dilatation is useful to distinguish PH (mean PA pressure ≥25 mmHg) from normal (mean PA pressure ≤ 20 mmHg), CT characteristics of borderline PH (mean PA pressure 21-24 mmHg) have not been described. We aimed to investigate whether patients with borderline PH already show PA dilatation and to assess the diagnostic accuracy of PA dilatation for borderline PH diagnosis. Between April 2003 and September 2008, consecutive symptomatic patients with a mean PA pressure below 25 mmHg on right heart catheterization who had a chest CT available were retrospectively included. PA diameters from chest CT were correlated with hemodynamic measurements and analyzed with respect to their accuracy of predicting borderline PH. Main PA diameters were significantly larger in 26 patients with borderline PH compared with 52 patients without PH (3.16 ± 0.53 vs. 2.78 ± 0.43 cm, P = 0.001). The main PA diameter on CT correlated with mean PA pressure (r = 0.496, P < 0.001) and pulmonary vascular resistance (r = 0.445, P < 0.001), and predicted borderline PH with sensitivity, specificity, negative and positive predictive values of 77%, 62%, 84%, and 50%, respectively, using a cutoff ≥2.9 cm. This first systematic investigation of CT parameters in symptomatic patients with mean PA pressures less than 25 mmHg could show that, even in patients with borderline PH, significant PA dilatation can be present, which was related to PA pressure and pulmonary vascular resistance. This can be useful for identification of patients with borderline PH for further study and to prompt further diagnostic work-up of possible underlying diseases.

The ratio of right ventricular volume to left ventricular volume reflects the impact of pulmonary regurgitation independently of the method of pulmonary regurgitation quantification

BACKGROUND

Previous studies have advocated quantifying pulmonary regurgitation (PR) by using PR volume (PRV) instead of commonly used PR fraction (PRF). However, physicians are not familiar with the use of PRV in clinical practice. The ratio of right ventricle (RV) volume to left ventricle volume (RV/LV) may better reflect the impact of PR on the heart than RV end-diastolic volume (RVEDV) alone. We aimed to compare the impact of PRV and PRF on RV size expressed as either the RV/LV ratio or RVEDV (mL/m(2)).

METHODS

Consecutive patients with repaired tetralogy of Fallot were included (n=53). PRV, PRF and ventricular volumes were measured with the use of cardiac magnetic resonance.

RESULTS

RVEDV was more closely correlated with PRV when compared with PRF (r=0.686, p<0.0001, and r=0.430, p=0.0014, respectively). On the other hand, both PRV and PRF showed a good correlation with the RV/LV ratio (r=0.691, p<0.0001, and r=0.685, p<0.0001, respectively). Receiver operating characteristic analysis showed that both measures of PR had similar ability to predict severe RV dilatation when the RV/LV ratio-based criterion was used, namely the RV/LV ratio>2.0 [area under the curve (AUC)(PRV)=0.770 vs AUC(PRF)=0.777, p=0.86]. Conversely, with the use of the RVEDV-based criterion (>170mL/m(2)), PRV proved to be superior over PRF (AUC(PRV)=0.770 vs AUC(PRF)=0.656, p=0.0028].

CONCLUSIONS

PRV and PRF have similar significance as measures of PR when the RV/LV ratio is used instead of RVEDV. The RV/LV ratio is a universal marker of RV dilatation independent of the method of PR quantification applied (PRF vs PRV).