Synthesis and preclinical evaluation of BOLD-100 radiolabeled with ruthenium-97 and ruthenium-103

BOLD-100 (formerly IT-139, KP1339), a well-established chemotherapeutic agent, is currently being investigated in clinical trials for the treatment of gastric, pancreatic, colorectal, and bile duct cancer. Despite numerous studies, the exact mode of action is still the subject of discussions. Radiolabeled BOLD-100 could be a powerful tool to clarify pharmacokinetic pathways of the compound and to predict therapy responses in patients using nuclear molecular imaging prior to the therapy. In this study, the radiosyntheses of carrier-added (c.a.) [97/103Ru]BOLD-100 were performed with the two ruthenium isotopes ruthenium-103 (103Ru; β-, γ) and ruthenium-97 (97Ru; EC, γ), of which in particular the latter isotope is suitable for imaging by single-photon emission computed tomography (SPECT). To identify the best tumor-to-background ratio for diagnostic imaging, biodistribution studies were performed with two different injected doses of c.a. [103Ru]BOLD-100 (3 and 30 mg kg-1) in Balb/c mice bearing CT26 allografts over a time period of 72 h. Additionally, ex vivo autoradiography of the tumors (24 h p.i.) was conducted. Our results indicate that the higher injected dose (30 mg kg-1) leads to more unspecific accumulation of the compound in non-targeted tissue, which is likely due to an overload of the albumin transport system. It was also shown that lower amounts of injected c.a. [103Ru]BOLD-100 resulted in a relatively higher tumor uptake and, therefore, a better tumor-to-background ratio, which are encouraging results for future imaging studies using c.a. [97Ru]BOLD-100.

Being fit in the COVID-19 era and future epidemics prevention: Importance of cardiopulmonary exercise test in fitness evaluation

Endurance and resistance physical activity have been shown to stimulate the production of immunoglobulins and boost the levels of anti-inflammatory cytokines, natural killer cells, and neutrophils in the bloodstream, thereby strengthening the ability of the innate immune system to protect against diseases and infections. Coronavirus disease 19 (COVID-19) greatly impacted people's cardiorespiratory fitness (CRF) and health worldwide. Cardiopulmonary exercise testing (CPET) remains valuable in assessing physical condition, predicting illness severity, and guiding interventions and treatments. In this narrative review, we summarize the connections and impact of COVID-19 on CRF levels and its implications on the disease's progression, prognosis, and mortality. We also emphasize the significant contribution of CPET in both clinical evaluations of recovering COVID-19 patients and scientific investigations focused on comprehending the enduring health consequences of SARS-CoV-2 infection.

High and intermediate risk pulmonary embolism in the ICU

Pulmonary embolism (PE) is a common and important medical emergency, encountered by clinicians across all acute care specialties. PE is a relatively uncommon cause of direct admission to the intensive care unit (ICU), but these patients are at high risk of death. More commonly, patients admitted to ICU develop PE as a complication of an unrelated acute illness. This paper reviews the epidemiology, diagnosis, risk stratification, and particularly the management of PE from a critical care perspective. Issues around prevention, anticoagulation, fibrinolysis, catheter-based techniques, surgical embolectomy, and extracorporeal support are discussed.

Social representations of intellectual disability; a comparison between cultures

OBJECTIVES

People with Intellectual disability consistently appear to be one of the most looked-down upon and repressed subgroups of society in many cultures. The main aim of this study was to compare social representations of intellectual disability in its various aspects between different cultures.

MATERIALS AND METHODS

The study was conducted in four different sites: Beirut-Lebanon, Algiers-Algeria, Tours-France and Namur-Belgium. Participants were asked to complete a questionnaire evaluating social representations of intellectual disability.

RESULTS

A total of 755 participants consented to take part in the study. Gender only affected social representations in the Lebanese population. Overall, Algerians appeared to have the least positive social representations and Lebanon to have more positive attitudes, while France and Belgium tended to have the most favourable representations.

DISCUSSION AND CONCLUSIONS

Findings highlight the imbalance between a European and a non-European country showing the importance of developing tailored interventions to improve general attitudes towards intellectual disability.

Pulmonary Vasodilator Response of Combined Inhaled Epoprostenol and Inhaled Milrinone in Cardiac Surgical Patients

BACKGROUND

Pulmonary hypertension (PH) and right ventricular (RV) dysfunction are major complications in cardiac surgery. Intraoperative management of patients at high risk of RV failure should aim to reduce RV afterload and optimize RV filling pressures, while avoiding systemic hypotension, to facilitate weaning from cardiopulmonary bypass (CPB). Inhaled epoprostenol and inhaled milrinone (iE&iM) administered in combination before CPB may represent an effective strategy to facilitate separation from CPB and reduce requirements for intravenous inotropes during cardiac surgery. Our primary objective was to report the rate of positive pulmonary vasodilator response to iE&iM and, second, how it relates to perioperative outcomes in cardiac surgery.

METHODS

This is a retrospective cohort study of consecutive patients with PH or RV dysfunction undergoing on-pump cardiac surgery at the Montreal Heart Institute from July 2013 to December 2018 (n = 128). iE&iM treatment was administered using an ultrasonic mesh nebulizer before the initiation of CPB. Demographic and baseline clinical data, as well as hemodynamic, intraoperative, and echocardiographic data, were collected using electronic records. An increase of 20% in the mean arterial pressure (MAP) to mean pulmonary artery pressure (MPAP) ratio was used to indicate a positive response to iE&iM.

RESULTS

In this cohort, 77.3% of patients were responders to iE&iM treatment. Baseline systolic pulmonary artery pressure (SPAP) (odds ratio [OR], 1.63; 95% confidence interval [CI], 1.24-2.16 per 5 mm Hg; P = .0006) was found to be a predictor of pulmonary vasodilator response, while a European System for Cardiac Operative Risk Evaluation (EuroSCORE II) score >6.5% was a predictor of nonresponse to treatment (≤6.5% vs >6.5% [reference]: OR, 5.19; 95% CI, 1.84-14.66; P = .002). Severity of PH was associated with a positive response to treatment, where a higher proportion of responders had MPAP values >30 mm Hg (42.4% responders vs 24.1% nonresponders; P = .0237) and SPAP values >55 mm Hg (17.2% vs 3.4%; P = .0037). Easier separation from CPB was also associated with response to iE&iM treatment (69.7% vs 58.6%; P = .0181). A higher proportion of nonresponders had a very difficult separation from CPB and required intravenous inotropic drug support compared to responders, for whom easy separation from CPB was more frequent. Use of intravenous inotropes after CPB was lower in responders to treatment (8.1% vs 27.6%; P = .0052).

CONCLUSIONS

A positive pulmonary vasodilator response to treatment with a combination of iE&iM before initiation of CPB was observed in 77% of patients. Higher baseline SPAP was an independent predictor of pulmonary vasodilator response, while EuroSCORE II >6.5% was a predictor of nonresponse to treatment.

Echocardiographic diversity associated with exercise capacity in heart failure precursor stage B: the Project Baseline Health Study

Background

The current paradigm to stage heart failure (HF) defines precursor stage B (or “pre-HF”) as having any subclinical change in cardiac structure or function. Yet, HF risk factors and type of cardiac abnormality may induce clinically relevant heterogeneity in HF stage B. Therefore, we assessed clinical and echocardiographic heterogeneity within stage B HF and its association with exercise capacity in a large community-based sample.

Methods

2071 participants to the Baseline Health Study (50.4±17.0 years, 56.2% women, 37.8% hypertensive) underwent echocardiography and physical performance testing including 6-minute walk (6MWT) and treadmill exercise test. We defined echocardiographic profiles of left and right heart remodeling and dysfunction using sex-specific internal reference values. We assessed HF stages (0-A-B-C-D) following HF societies recommendations. stage B participants were stratified according to presence/absence of HF risk factors and to the most severe echocardiographic abnormality present (reduced ejection fraction (EF), left ventricular (LV) hypertrophy/diastolic dysfunction or other abnormalities). We reported associations between physical performance metrics and HF (sub)stages.

Results

Stage B HF was present in 516 participants (24.9%). Within stage B HF, we observed a large diversity in echocardiographic profiles. Yet, stage B participants without HF risk factors (n=96, 18.6% of stage B) predominantly presented echo abnormalities other than LV diastolic dysfunction, hypertrophy and reduced EF, while their physical performance profile resembled that of people with normal echocardiography without HF risk factors. In contrast, stage B participants with HF risk factors (n=420) were characterized by LV diastolic dysfunction, hypertrophy or reduced EF, three phenotypes associated with lower 6MWT distance and lower exercise capacity. Concomitant presence of HF risk factors and LV dysfunction/hypertrophy was associated with worst physical performance.

Conclusions

We observed a wide clinical and echocardiographic diversity affecting physical performance in HF precursor stage B when defined by the current staging paradigm. Concomitant presence of HF risk factors and LV dysfunction/hypertrophy may mark individuals at highest risk for progression towards overt HF.

Funding Acknowledgement

Type of funding sources: Other. Main funding source(s): This research was made supported by an institutional research grant from Verily Inc. (CA, USA) and by the Research Foundation Flanders (Belgium).

Elucidating tricuspid Doppler signal interpolation and its implication for assessing pulmonary hypertension

Doppler echocardiography plays a central role in the assessment of pulmonary hypertension (PAH). We aim to improve quality assessment of systolic pulmonary arterial pressure (SPAP) by applying a cubic polynomial interpolation to digitized tricuspid regurgitation (TR) waveforms. Patients with PAH and advanced lung disease were divided into three cohorts: a derivation cohort (n = 44), a validation cohort (n = 71), an outlier cohort (n = 26), and a non-PAH cohort (n = 44). We digitized TR waveforms and analyzed normalized duration, skewness, kurtosis, and first and second derivatives of pressure. Cubic polynomial interpolation was applied to three physiology-driven phases: the isovolumic phase, ejection phase, and "shoulder" point phase. Coefficients of determination and a Bland-Altman analysis was used to assess bias between methods. The cubic polynomial interpolation of the TR waveform correlated strongly with expert read right ventricular systolic pressure (RVSP) with R 2 > 0.910 in the validation cohort. The biases when compared to invasive SPAP measured within 24 h were 6.03 [4.33; 7.73], -2.94 [1.47; 4.41], and -3.11 [-4.52; -1.71] mmHg, for isovolumic, ejection, and shoulder point interpolations, respectively. In the outlier cohort with more than 30% difference between echocardiographic estimates and invasive SPAP, cubic polynomial interpolation significantly reduced underestimation of RVSP. Cubic polynomial interpolation of the TR waveform based on isovolumic or early ejection phase may improve RVSP estimates.

Sclerostin and bone turnover markers response to cycling and running at the same moderate-to-vigorous exercise intensity in healthy men

BACKGROUND

Recreational cycling is a popular activity which stimulates and improves cardiovascular fitness. The corresponding benefits for bone are unclear.

PURPOSE

This study examined the effect of running (high-impact) vs. cycling (low-impact), at the same moderate-to-vigorous exercise intensity, on markers of bone formation (N-terminal propeptide of type I collagen, PINP) and bone resorption (C-telopeptide of type I collagen, CTX-1), a non-collagenous bone remodeling marker (osteocalcin), as well as bone-modulating factors, including parathyroid hormone (PTH), irisin (myokine) and sclerostin (osteokine).

METHODS

Thirteen healthy men (23.7 ± 1.0 y) performed two progressive exercise tests to exhaustion (peak VO₂) on a cycle ergometer (CE) and on a treadmill (TM). On subsequent separate days, in randomized order, participants performed 30-min continuous running or cycling at 70% heart rate reserve (HRR). Blood was drawn before, immediately post- and 1 h into recovery.

RESULTS

PTH transiently increased (CE, 51.7%; TM, 50.6%) immediately after exercise in both exercise modes. Sclerostin levels increased following running only (27.7%). Irisin increased following both running and cycling. In both exercise modes, CTX-1 decreased immediately after exercise, with no significant change in PINP and osteocalcin.

CONCLUSION

At the same moderate-to-vigorous exercise intensity, running appears to result in a greater transient sclerostin response compared with cycling, while the responses of bone markers, PTH and irisin are similar. The longer-term implications of this differential bone response need to be further examined.

Proteomic profiling for detection of early-stage heart failure in the community

Background and purpose

Biomarkers may provide insight into the molecular mechanisms underlying cardiac remodelling and dysfunction. Using a targeted proteomic approach, we aimed to identify circulating biomarkers associated with early-stage heart failure and extract a proteome-based risk classifier for this condition.

Methods

575 community-based participants (mean age, 57 years; 51.7% women) underwent echocardiography and proteomic profiling (CVD II panel, Olink Proteomics). We applied partial least squares-discriminant analysis (PLS-DA) and a machine learning algorithm (extreme gradient boosting, XGBoost) to identify key proteins associated with echocardiographic abnormalities. We used Gaussian Mixture modelling for unbiased clustering to construct phenogroups based on influential proteins in PLS-DA and XGBoost.

Results

Of 87 proteins, 13 were important in PLS-DA and XGBoost modelling for detection of left ventricular (LV) remodelling, LV diastolic dysfunction and/or left atrial reservoir dysfunction: placenta growth factor, kidney injury molecule-1, prostasin, angiotensin-converting enzyme-2, galectin-9, cathepsin L1, matrix metalloproteinase-7, TNFR superfamily members 10A, 10B and 11A, interleukins-6 and 16 and alpha-1-microglobulin/bikunin precursor. Based on these proteins, the clustering algorithm divided the cohort into two distinct phenogroups, with each cluster grouping individuals with a similar protein profile. Participants belonging to the second cluster (n=118) were characterized by an unfavourable cardiovascular risk profile and adverse cardiac structure and function. The adjusted risk of presenting cardiac maladaptation was higher in this phenogroup than in the other cluster (P<0.0001).

Conclusion

We identified proteins reflecting renal function, extracellular matrix remodelling, angiogenesis and inflammation to be associated with echocardiographic signs of early-stage heart failure. Focused proteomic phenomapping discriminated individuals at high risk for cardiac maladaptation in the community.

Funding Acknowledgement

Type of funding sources: Public grant(s) – National budget only. Main funding source(s): Research Foundation Flanders

Temporal shift and accuracy of machine learning in heart transplant outcomes

Background

Accurate prediction of outcomes following a heart transplant is critical to explaining risks and benefits to patients and decision-making when considering potential organ offers. Given the large number of potential variables to be considered, this task may be most efficiently performed using machine learning (ML).

Purpose

We trained and tested different ML algorithms to accurately predict outcomes following a cardiac transplant using the United Network of Organ Sharing (UNOS) database.

Methods

We included 67 939 adult and pediatric patients enrolled in the UNOS database between January 1994 and December 2016 who underwent cardiac transplantation (median age 53 [IQR 38 – 60], 72.7% males). In our models, as an input, we included 114 features that have been collected from recipients and donors prior to transplant. The primary outcome was all-cause mortality at one-year post-transplant. We evaluated three different ML methods: XGBoost, Random Forest (RF) and L2 regularized logistic regression. Algorithms were trained and tested using shuffled 10-fold cross-validation (CV) as well as rolling CV. In the rolling CV, to mimic prospective procedure, ML models were trained by incrementally adding patients according to transplant year and testing models on the data in the following year. The hyperparameters, controlling the learning process, were tuned using Bayesian optimization. Prognostic accuracy for one-year all-cause mortality was characterized using the area under the receiver-operating characteristic curve (AUC).

Results

In total, 8,394 patients died within 1 year of transplant. We observed a substantial difference in prognostic accuracy between the shuffled 10-fold CV and the rolling CV. In the 10-fold CV, XGBoost and RF achieved high predictive performance with AUC of 0.848 (95% CI: 0.842–0.854) and 0.891 (95% CI: 0.886–0.896), respectively. In the rolling CV, which is a more realistic setting, AUC dropped to 0.673 (95% CI: 0.661–0.684) for XGBoost and 0.670 (0.657–0.683) for RF. Predictive performance of L2 regularized logistic regression remained stable across the two CV procedures, achieving AUC 0.669 (95% CI: 0.662–0.676) in the 10-fold shuffled CV and 0.665 (95% CI: 0.649–0.680) in the rolling CV procedure (Figure).

Conclusions

Our study suggests that ML models could be used to predict mortality in the first year post-transplant. We also show that the choice of CV procedure is crucial for evaluating ML models, particularly in data collected over a long period of time. The difference between the shuffled and rolling CV in the predictive performance of the tree-based ML models might indicate temporal dataset shift. In the rolling CV, all three methods achieved similar predictive performance.

Funding Acknowledgement

Type of funding sources: Public grant(s) – National budget only. Main funding source(s): Research Foundation Flanders (FWO)

The association of soluble ACE2 change with metabolic health, body composition and proteome dynamics during a weight loss diet intervention: implications for the COVID-19 pandemic

Background

Angiotensin-converting enzyme 2 (ACE2) serves protective functions in metabolic, cardiovascular, renal and pulmonary diseases and is linked to COVID-19 pathology. We explored the association between soluble AC2 (sACE2) and metabolic health and proteome dynamics during a weight loss diet intervention.

Methods

We analyzed 457 healthy individuals (mean age 39.8±6.6) with BMI 28–40 kg/m2 who participated in the Diet Intervention Examining the Factors Interacting with Treatment Success (DIETFITS). Biochemical markers of metabolic health and 236 proteins measured by Olink CVD II, CVD III and Inflammation arrays were available at baseline and 6 months following dietary intervention. We determined clinical and routine biochemical correlates of the diet-induced change in sACE2 (ΔsACE2) using stepwise linear regression. We then combined feature selection models and multivariable-adjusted linear regression to identify protein dynamics associated with ΔsACE2.

Results

sACE2 decreased significantly on average at 6-months in the diet intervention. A stronger decline in sACE2 during the diet intervention was independently associated with female sex, lower HOMA-IR and LDL cholesterol at baseline, and a stronger decline in HOMA-IR, triglycerides, HDL-cholesterol and fat mass. In line, participants with decreasing HOMA-IR and triglycerides had significantly higher odds for a decrease in sACE2 during the diet intervention than those who did not (P≤0.0073 for both). Feature selection models linked ΔsACE2 to changes in AMBP, E-selectin, HAOX1, KIM-1, MERTK, PGF, thrombomodulin and TRAIL-R2. ΔsACE2 remained independently associated with these protein changes in multivariable-adjusted linear regression.

Conclusion

Decrease in sACE2 during a weight loss diet intervention was associated with improvements in metabolic health, fat mass and markers of angiotensin peptide metabolism, vascular injury, renal function, chronic inflammation and oxidative stress. Our findings may improve the risk stratification, prevention, and management of cardiometabolic and COVID-19-related complications.

Funding Acknowledgement

Type of funding sources: Public grant(s) – National budget only. Main funding source(s): NIHResearch Foundation Flanders

An inflammatory aging clock (iAge) based on deep learning tracks multimorbidity, immunosenescence, frailty and cardiovascular aging

While many diseases of aging have been linked to the immunological system, immune metrics capable of identifying the most at-risk individuals are lacking. From the blood immunome of 1,001 individuals aged 8-96 years, we developed a deep-learning method based on patterns of systemic age-related inflammation. The resulting inflammatory clock of aging (iAge) tracked with multimorbidity, immunosenescence, frailty and cardiovascular aging, and is also associated with exceptional longevity in centenarians. The strongest contributor to iAge was the chemokine CXCL9, which was involved in cardiac aging, adverse cardiac remodeling and poor vascular function. Furthermore, aging endothelial cells in human and mice show loss of function, cellular senescence and hallmark phenotypes of arterial stiffness, all of which are reversed by silencing CXCL9. In conclusion, we identify a key role of CXCL9 in age-related chronic inflammation and derive a metric for multimorbidity that can be utilized for the early detection of age-related clinical phenotypes.

Production of scandium radionuclides for theranostic applications: towards standardization of quality requirements

In the frame of "precision medicine", the scandium radionuclides have recently received considerable interest, providing personalised adjustment of radiation characteristics to optimize the efficiency of medical care or therapeutic benefit for particular groups of patients. Radionuclides of scandium, namely scandium-43 and scandium-44 (43/44Sc) as positron emitters and scandium-47 (47Sc), beta-radiation emitter, seem to fit ideally into the concept of theranostic pair. This paper aims to review the work on scandium isotopes production, coordination chemistry, radiolabeling, preclinical studies and the very first clinical studies. Finally, standardized procedures for scandium-based radiopharmaceuticals have been proposed as a basis to pave the way for elaboration of the Ph.Eur. monographs for perspective scandium radionuclides.

Assessing post-exercise respiratory gas kinetics in clinical sample - a pilot study

Funding Acknowledgements

Type of funding sources: None.

Background

Cardiopulmonary exercise testing (CPX) is established in the evaluation of patients with cardiac and pulmonary diseases, and its clinical utility seems to be expanding.  Currently the most important diagnostic and prognostic ventilatory metrics of CPX rely on the exercise phase. Nevertheless, a consistent body of evidence suggests that important information can be derived from the recovery phase, especially in the first few minutes after exercise. In this context, patients with heart failure (HF) demonstrate a slower recovery of the oxygen consumption (VO2) compared with healthy individuals. Purpose: To comprehensively investigate the behavior of respiratory gases during recovery from CPX in a diverse cohort of HF patients. Methods: All individuals who performed CPX at the department of cardiology of Stanford University Hospital were eligible for the study. Patients were included in the experimental group if they (i) were recorded for five minutes after the exercise phase of CPX and (ii) had documented heart failure. They were excluded if they had other clinical diagnoses which may be responsible for exercise intolerance or symptoms or were unable to give informed consent. Healthy controls were recruited from the local community and were included if they did not have documented or suspected disease. Respiratory gases were collected on a breath-by-breath basis and analysed after applying a 30 second rolling average filter. Metrics were analyzed as absolute values, percentage change from peak and the half-time of recovery (T ½; i.e. the duration until a metric had returned to ½ of its value at peak). Data was analyzed over time within patients and averages between groups using parametric statistical methods. In accordance with previous studies, the amount of change in a metric after exercise is presented as the "magnitude" of overshoot. Results: 32 patients with HF (11 Female, 47 ± 13 yrs) and 30 healthy subjects (14 Female, 43 ± 12 yrs) were included. A comparison of ventilatory metrics during recovery between HF and controls is depicted in Figure 1. Peak VO2 was 1135 ± 419 mL/min (13.5 ± 3.8 mL/Kg/min) vs 2408 ± 787 mL/min (32.5 ± 9.0 mL/Kg/min); P <0.01. A significant difference between patients with HF and healthy subjects was found in T ½ of VO2 (111.3 ± 51.0s vs 58.0 ± 13.2s, p < 0.01) and VCO2 (132.0 ± 38.8s vs 74.3 ± 21.1s, p < 0.01). The magnitude of the overshoot was also found to be significantly reduced in patients with HF for VE/VO2 (41.9 ± 29.1% vs 62.1 ± 17.7%, P < 0.01), RQ (25.0 ± 13.6% vs 38.7 ± 15.1%, p < 0.01) and PETO2 (7.2 ± 3.3% vs 10.1 ± 4.6%, p < 0.01). Finally, the magnitude of the RQ overshoot showed a moderate correlation with peak VO2 (ϱ=0.58, p < 0.01). Conclusions: We observed that ventilatory kinetics measured in early recovery after CPX differ significantly between healthy subjects and patients with HF. The assessment of post exercise respiratory gases in a clinical setting may add to the prognostic and diagnostic value of CPX in heart failure.

Abstract Figure.

Retraction notice to ICAM-1 PROMOTES THE ABNORMAL ENDOTHELIAL CELL PHENOTYPE IN CHRONIC THROMBOEMBOLIC PULMONARY HYPERTENSION

This article has been retracted: please see Elsevier Policy on Article Withdrawal (https://www.elsevier.com/about/our-business/policies/article-withdrawal). This article has been retracted at the request of the Authors. This request follows an examination by The Editors of the uncut gels provided by the authors, which led the Editors to conclude that data were compromised in the following western blot images: Figure 3C, Figure 5B and Figure 6B. Duplicated data for the beta actin images were found in Figures 5 and 6. Examination of the raw data used for the western blot quantification also revealed frequent duplicated data. The microscopy data in Figure 5A also has features compatible with compromised data although the raw data were not available to the Editors due to the regrettable death of Dr. Saadia Eddahibi. All of the remaining authors agree with the retraction and apologize to the Editors and the readers of The Journal for difficulties this issue has caused.

Left atrial reservoir strain in relation to metabolic and inflammatory biomarkers: a community-based study

Background

The pathophysiological mechanisms that underlie progressive left atrium (LA) remodelling and dysfunction are only partially understood. Metabolic disturbances and chronic inflammation might mediate LA dysfunction. To date, population data investigating the contribution of these processes to LA reservoir dysfunction remain scarce.

Purpose

In a large population sample, we investigated the association between LA reservoir function and a panel of 38 metabolic and inflammatory biomarkers.

Methods

In 1236 community-dwelling individuals (mean age, 51.0 years; 51.5% women), we echocardiographically assessed LA reservoir strain (LARS) using 2D speckle-tracking analysis. LA reservoir dysfunction was defined as having LARS <23%. We applied partial least squares-discriminant analysis (PLS-DA) to identify biomarkers associated with LA dysfunction. We further explored the associations between LARS and selected biomarkers that were the most influential in PLS-DA, while adjusting for important clinical correlates such as age, sex, body mass index (BMI), heart rate, systolic blood pressure (BP) and antihypertensive treatment. We applied stepwise regression to identify the clinical features and circulating biomarkers most valuable for prediction of abnormal LARS.

Results

The three latent factors constructed from the panel of 38 biomarkers during PLS-DA explained 16.9% of the variation between the normal and the impaired LA function group. The PLS-DA model discriminated between normal and abnormal LA reservoir strain with 79% accuracy (P<0.0001). In PLS-DA, serum uric acid, serum insulin, γ-glutamyl transferase, interleukin-6, D-dimer and triglycerides were the top biomarkers responsible for class discrimination. On average, these top biomarkers were higher in the LA dysfunction group as compared to their normal counterparts (P<0.0001 for all). In multivariable-adjusted continuous analyses, LARS decreased significantly with the level of serum insulin, serum uric acid and γ-glutamyl transferase (P≤0.0035 for all). Of the clinical correlates and the top biomarkers selected in PLS-DA, stepwise regression models highlighted age, BMI, systolic BP, serum insulin, serum uric acid and interleukin-6 as the main predictors of an impaired LA reservoir function (see figure). Conjointly, these clinical and biochemical features identified LA reservoir dysfunction with an overall accuracy of 85%.

Conclusions

Circulating markers of insulin resistance, hyperuricemia and chronic inflammation were independently associated with impaired LA reservoir function. These markers may help to further unravel the pathophysiological processes behind LA maladaptation and improve the management of early LA dysfunction in the community.

Funding Acknowledgement

Type of funding source: Public grant(s) – National budget only. Main funding source(s): Research Foundation Flanders

Subclinical left atrial dysfunction profiles for prediction of cardiac outcome in the general population

Background

Echocardiographic screening for subclinical left atrial (LA) dysfunction might enhance the prediction of cardiac diseases such as atrial fibrillation (AFib) in the community. To date, however, outcome-driven definitions of early-stage LA dysfunction remain scarce.

Purpose

In a large population sample, we sought to extract outcome-driven thresholds for echocardiographic indexes of LA function to define subclinical left atrial (LA) dysfunction and assess the prognostic value of these echocardiographic criteria for prediction of cardiac events.

Methods

In 1306 community-dwelling individuals (mean age, 50.7 years; 51.6% women), we assessed LA function and left ventricular (LV) global longitudinal strain (LS) by echocardiography. Using receiver-operating curve threshold analysis, we derived outcome-driven cut-offs for LA emptying fraction (LAEF) and LA reservoir strain (LARS) that best balanced the cardiac event prediction (i.e. cut-offs yielding the highest Youden index (=sensitivity+specificity-1)). Next, we constructed LA dysfunction profiles and integrative LA/LV strain profiles based on the extracted cut-offs for LAEF and LARS and a validated definition of impaired LV global LS. We assessed the prognostic performance of these profiles in predicting the incidence of cardiac events and AFib (mean follow-up, 8.5 years).

Results

During follow-up, 93 participants experienced a cardiac event (8.3 events/1000 person-years) and 27 developed AFib (2.3 events/1000 person-years). LAEF<55% and LARS<23% yielded the highest Youden indexes and thus provided the most balanced prediction of incident AFib. When applying these cut-offs, abnormal LAEF and LARS were respectively present in 27.0% and 18.1% of the cohort. Abnormal LARS was independently associated with higher risk for cardiac events (hazard ratio (HR) versus normal LA phenotype: 2.11, P=0.0021). Both abnormal LAEF (HR: 2.57) and abnormal LARS (HR: 3.28) predicted incident AFib (P≤0.029). As compared to subjects free from any LA dysfunction, those with both LAEF<55% and LARS<23% had a significantly higher risk to develop cardiac events (HR: 2.10; P=0.014) and AFib (HR: 6.45; P=0.0036). Of the integrative LA/LV strain profiles, the concomitant presence of an impaired LARS and LV global LS independently elevated the risk for cardiac events (HR: 2.81; P=0.0012) and AFib (HR: 4.36, P=0.0071) as compared to normal counterparts. Both the degree of LA dysfunction and the integrative LA/LV strain profiles improved the prognostic accuracy beyond clinical risk models and risk scores.

Conclusions

We validated population-based and outcome-driven definitions of subclinical LA dysfunction predicting cardiac events independent of conventional risk factors. Echocardiographic screening for subclinical LA and LV systolic dysfunction might enhance the prediction of cardiac diseases such as AFib in the community, empowering clinicians to timely intervene with the disease development.

Prediction of cardiac events

Funding Acknowledgement

Type of funding source: Public grant(s) – National budget only. Main funding source(s): Research Foundation Flanders, Internal Funds KU Leuven

Trends in Left Ventricular Ejection Fraction for Patients With a New Diagnosis of Heart Failure

BACKGROUND

The left ventricular ejection fraction (LVEF) guides treatment of heart failure, yet this data has not been systematically collected in large data sets. We sought to characterize the epidemiology of incident heart failure using the initial LVEF.

METHODS

We identified 219 537 patients in the Veterans Affairs system between 2011 and 2017 who had an LVEF documented within 365 days before and 30 days after the heart failure diagnosis date. LVEF was obtained from natural language processing from imaging and provider notes. In multivariate analysis, we assessed characteristics associated with having an initial LVEF <40%.

RESULTS

Most patients were male and White; a plurality were within the 60 to 69 year age decile. A majority of patients had ischemic heart disease and a high burden of co-morbidities. Over time, presentation with an LVEF <40% became slightly less common, with a nadir in 2015. Presentation with an initial LVEF <40% was more common in younger patients, men, Black and Hispanic patients, an inpatient presentation, lower systolic blood pressure, lower pulse pressure, and higher heart rate. Ischemic heart disease, alcohol use disorder, peripheral arterial disease, and ventricular arrhythmias were associated with an initial LVEF <40%, while most other comorbid conditions (eg, atrial fibrillation, chronic obstructive pulmonary disease, malignancy) were more strongly associated with an initial LVEF >50%.

CONCLUSIONS

For patients with heart failure, particularly at the extremes of age, an initial preserved LVEF is common. In addition to clinical characteristics, certain races (Black and Hispanic) were more likely to present with a reduced LVEF. Further studies are needed to determine if racial differences are due to patient or health systems issues such as access to care.

Limitations of right ventricular annular parameters in the early postoperative period following pulmonary endarterectomy: an observational study

OBJECTIVES

Echocardiographic right ventricular (RV) annular parameters are probably not as reliable to evaluate the surgical success in the postoperative period after pulmonary endarterectomy (PEA), whereas RV end-diastolic/left ventricular end-diastolic area ratio (RVEDA/LVEDA ratio) could be more useful. This study examined the relationship between RV annular parameters or RVEDA/LVEDA ratio and ideal cardiac index (ICI), before and after PEA.

METHODS

Among 80 patients who underwent PEA, the relationships between RVEDA/LVEDA ratio (21 patients), or tricuspid annular plane systolic excursion (32 patients), or systolic tricuspid annular velocity (55 patients) and ICI were modelled.

RESULTS

Forty-eight hours following PEA, mean pulmonary artery pressure decreased (26 ± 6 vs 46 ± 12 mmHg, P < 0.0001) and ICI improved (2.8 ± 0.8 vs 3.0 ± 0.9 l/min/m2, P = 0.02). In contrast to the moderate association between RV annular indices and ICI in the preoperative period, no significant relationship was found in the postoperative period (r = 0.54 and 0.17 for tricuspid annular plane systolic excursion and r = 0.46 and 0.16 for systolic tricuspid annular velocity, respectively). The RVEDA/LVEDA ratio significantly decreased postoperatively (0.97 ± 0.21 vs 1.19 ± 0.43, P = 0.002) and was correlated with ICI both in preoperative and postoperative periods (r = 0.57 and 0.57, respectively). There was a significant correlation between changes in RVEDA/LVEDA ratio and changes in total pulmonary resistance.

CONCLUSIONS

Improved ICI and RVEDA/LVEDA ratio reflected the surgical success of PEA and lowering of total pulmonary resistances. In contrast to the RV/left ventricular area ratio, annular RV indices associated poorly with postoperative ICI. Recognizing this limitation is important in minimizing the overdiagnosis of RV dysfunction after PEA.

P2488The 2013 ACC/AHA pooled cohort equations and insulin resistance status for detection of early-stage heart failure in the community

Objectives

Detection of heart failure (HF) in its subclinical phase would allow timely initiation of preventive measures that counter its pathophysiology. Here, we assessed the usefulness of traditional cardiovascular (CV) risk assessment and insulin resistance status to detect early-stage HF.

Methods

In 984 participants (mean age, 57.0 years, 52.3% women), we derived echocardiographic indexes of left ventricular (LV) structure and function and calculated the 10-year risk for a first atherosclerotic CV disease (ASCVD) using the 2013 ACC/AHA risk score. We assessed the discriminatory value of this risk score to detect LV maladaptation and the improvements in reclassification by insulin resistance status (HOMA-IR).

Results

The probability for LV maladaptation rose progressively with the 10-year ASCVD risk increasing. Participants at high 10-year ASCVD risk (>7.5%) had indeed significantly higher odds for LV concentric remodeling (odds ratio, 4.84), LV hypertrophy (OR, 5.93), abnormal LV longitudinal strain (OR, 2.04) and LV diastolic dysfunction (OR, 25.3) as compared to those at low ASCVD risk (<2.5%; P≤0.0003). Adding markers of insulin resistance to the ACC/AHA risk score moderately improved the integrated discrimination and net reclassification of all LV maladaptive phenotypes (P≤0.022) except LV diastolic dysfunction (P≥0.059). LV remodeling and abnormal LS was particularly more likely in insulin-resistant participants with a 10-year ASCVD risk between 5% and 15% than in their insulin-sensitive counterparts.

Prediction of early-stage HF profiles 2013 ACC/AHA risk score Addition of insulin resistance status to the 2013 ACC/AHA risk score AUC (95% CI) Integrated Discrimination Improvement Net Reclassification Improvement Absolute IDI (%) P value NRI (95% CI) P value LV concentric remodeling 0.70 (0.66 to 0.74) 0.0083 (11.3%) 0.022 0.23 (0.067 to 0.39) 0.0058 LV hypertrophy 0.70 (0.66 to 0.74) 0.017 (20.7%) 0.0033 0.27 (0.11 to 0.43) 0.0011 Abnormal LV LS 0.56 (0.53 to 0.62) 0.022 (202.0%) <0.0001 0.33 (0.18 to 0.49) <0.0001 LV diastolic dysfunction 0.82 (0.78 to 0.86) 0.0007 (0.45%) 0.84 0.093 (−0.11 to 0.30) 0.38 ≥2 LV abnormalities 0.76 (0.72 to 0.80) 0.0087 (7.3%) 0.071 0.22 (0.042 to 0.40) 0.016 The integrated discrimination improvement (IDI) and net reclassification improvement (NRI) reflect the improvements in classification by adding insulin resistance (by HOMA-IR) to the 2013 ACC/AHA risk score. HOMA-IR, Homeostatic Model for Assessment of Insulin Resistance; LS, longitudinal strain; LV, left ventricular.

Risk enhancers of LV maladaptation

Conclusions

The 2013 ACC/AHA risk score adequately captured the risk for echocardiographic phenotypes of early-stage HF. As risk enhancer, insulin resistance might improve risk stratification of subclinical HF in subjects at intermediate risk.

Acknowledgement/Funding

The European Union, European Research Council and the Flanders Scientific Research Fund supported this study.

P4419The association between ECG voltage and left-ventricular mass, sex, body size and the distance between the heart and chest wall in college athletes

Background

The ECG is widely used in pre-participation evaluation (PPE) of athletes (ATH). While it is assumed that greater than normal QRS voltages reflect physiologically increased left ventricular mass (LVM), this has not been adequately demonstrated in ATH.

Purpose

To examine the relation between QRS voltage on surface ECG and LVM and explore if the distance from the chest wall to mid-LV (CWLVdis) affects QRS voltage in ATH.

Methods

We examined digitized ECG data and echocardiograms in college ATH, obtained as part of routine PPE in years 2010–16. ECG parameters included R and S-wave voltage components of the Sokolow-Lyon (S-L) and Cornell criteria for LV hypertrophy (i.e. SV1 + RV5-V6 and RaVL + SV3, respectively). Transthoracic 2D echocardiography was used to determine LVM (area-length method) and the CWLVdis (detailed in Fig1A). S-L positive (SV1 + RV5-V6 >35 mV or RaVL >11 mV) ATH were compared to S-L negative by t-test, and univariate correlation and multivariable regression analysis was used to explore independent effects of body characteristics, sex, LVM and CWLVdis on QRS voltage.

Results

Included were 227 ATH (age 18.6±0.7 yr; 85% male; 60%/33% Caucasian/Afro-american). Of these, 66% played American football, 18% volleyball and 16% basketball.

Overall, mean LVM was 174±37 g (range 96–284 g), and BSA-indexed LVM was 78±12 g/m2 (range 49–108 g/m2). Mean CWLVdis was 8.5±1.1 cm (range 5.6–11.3 cm) and was greater in males (p<0.001, Fig1B).

Forty-six ATH (24%, all male) were S-L positive and no ATH were positive according to Cornell criteria. S-L positive ATH had lower BMI (25.3±3.5 vs 26.9±4.9, p=0.012), greater absolute LVM (189.1±31.3 vs. 170.1±37.4 g, p=0.002) and greater BSA-indexed LVM (85.3±10.3 vs. 76.6±11.7 g/m2, p<0.001) than S-L negative ATH. The CWLVdis was similar between S-L positive and negative ATH (8.4±1.2 vs. 8.6±1.1, respectively, p=0.213).

CWLVdis was more strongly correlated to body mass (r=0.73, p<0.001, Fig. 1C) than to height (r=0.34, p<0.001). LVM correlated weakly to ECG voltage as combined in the S-L or Cornell criteria (Fig. 1C). CWLVdis was weakly correlated with R in aVL, V5 and V6 (r=0.21, 0.16 and 0.16, all p<0.02).

In multivariate analysis, male sex (β=0.31), LVM (β=0.45) and body mass index (β=-0.37) were independently associated with the S-L summed voltage (R2 0.26, p<0.001). For Cornell summed voltage, only sex was an independent predictor (β=0.48, R2 0.22, p<001).

Figure 1

Conclusion

The R and S wave ECG amplitudes used in the two most common ECG criteria for LV hypertrophy were weakly related in the highest to lowest order to sex, LVM, body size and the distance from the LV to the chest wall in our college ATH.

P3819Machine learning for predicting early left ventricular abnormalities in the general population

Background

Current heart failure guidelines emphasize the importance of timely detection of subclinical left ventricular (LV) remodelling and dysfunction for more precise risk stratification of asymptomatic subjects. Both LV diastolic dysfunction (LVDD) and LV hypertrophy (LVH) as assessed by echocardiography are known independent prognostic markers of future cardiovascular events in the community. However, selective screening strategies of individuals at risk who would benefit most from in-depth cardiac phenotyping are lacking.

Purpose

We assess the utility of several Machine Learning (ML) classifiers built on clinical and biochemical features for detecting subclinical LV abnormalities.

Methods

We included 1407 participants (mean age, 51 years, 51% women) randomly recruited from the general population. We used echocardiographic parameters reflecting LV diastolic function and structure to define LV abnormalities (LVDD, n=239; LVH, n=135). After that four supervised ML algorithms (Random Forest (RF), Gradient Boosting (GD), Stochastic Gradient Descent (SGD) and Support Vector Machines (SV)) were built based on routine clinical, hemodynamic and laboratory data (features; n=61) to categorize LVDD and LVH (two prediction tasks). We applied a 10-fold stratified cross-validation set-up.

Results

ML classifiers exhibited a high area under the ROC (AUC) for predicting LVDD with values between 88.5% and 93.1% (Figure, left panel). Age, BMI, different components of blood pressure, antihypertensive treatment, routine biomarkers such as serum electrolytes, creatinine, blood sugar, leptin, uric acid, lipid profile, as well as blood cell counts were the top selected features for predicting LVDD. Prediction AUC of ML algorithms for detection of LVH was somewhat lower than for LVDD and ranged from 72.5% to 78.7% (Figure, right panel). The top selected features for LVH classifier were similar to those of LVDD, but also included social class, serum gamma-glutamyl transferase, fasting insulin, plasma renin activity and cortisol.

ROC curves (sensitivity-1-specificity)

Conclusions

ML algorithms combining routinely measured clinical and laboratory data have shown high accuracy of LVDD and LVH prediction. These ML classifiers might be useful to preselect individuals at risk for further in depth echocardiographic examination, monitoring and implementation of preventive strategies in order to delay transition to disease symptoms.

6075Workload adjusted blood pressure response rather than peak systolic blood pressure is associated with increased all-cause mortality in males; results from 7097 treadmill exercise tests

Background

Systolic blood pressure (SBP) is routinely measured during exercise testing (ET) and is in part determined by cardiac output and peripheral vascular resistance. A frequently used threshold for defining hypertensive response to exercise is ≥210 mmHg but this does not account for the fact that SBP is related to workload, via cardiac output.

Purpose

To examine the prognostic implications of considering external workload (METs) adjusted SBP response to exercise.

Methods

We reviewed all symptom-limited treadmill ET in males between 1987 and 2007 at a single centre (inclusion/exclusion criteria detailed in figure 1A). SBP was measured standing at rest and at peak exercise. Workload adjusted BP response with exercise (SBP/MET slope) was calculated as ΔSBP/ΔMET. METs were calculated from peak speed and grade according to the standard American College of Sports Medicine (ACSM) formula. Age-predicted peak METs was calculated as: 18 - 0.15 × age. Ten-year Cox proportional hazard ratios (HR) with 95% confidence intervals were calculated and adjusted as outlined in figure 1B.

Results

7097 subjects were included, of which 1559 (22%) died within 10 years. Survivors were younger (57.2±10.6 y vs. 64.5±10.3 y, p<0.001) and reached higher % of age-predicted METs (97±33% vs. 82±33%, p<0.001). Survivors had higher peak SBP (181±26 vs. 176±27 mmHg, p<0.001) as well as greater ΔSBP (49±22 vs. 42±22 mmHg, p<0.001), while they had lower SBP/MET slope (7.0±4.4 vs. 8.9±6.5 mmHg/MET, p<0.001). A peak SBP ≥210 mmHg was associated with better survival; 10-yr adjusted HR: 0.76 (0.64–0.88, p<0.001). In contrast, a higher SBP/MET slope was associated with increased mortality (table 1).

Table 1. Ten year adjusted hazard ratios Variable HR (95% CI) P Variable HR (95% CI) P Variable HR (95% CI) P Peak SBP, Q1: 100–159 mmHg REF REF Delta SBP, Q1: 1–29 mmHg REF REF SBP/MET slope, Q1: 0.2–4.2 REF REF Peak SBP, Q2: 160–179 mmHg 0.81 (0.71–0.94) 0.006 Delta SBP, Q2: 30–46 mmHg 0.80 (0.70–0.91) 0.001 SBP/MET slope, Q2: 4.3–6.2 0.95 (0.81–1.12) 0.562 Peak SBP, Q3: 180–199 mmHg 0.68 (0.58–0.78) <0.001 Delta SBP, Q3: 47–61 mmHg 0.76 (0.66–0.88) <0.001 SBP/MET slope, Q3: 6.2–9.1 1.18 (1.01–1.37) 0.032 Peak SBP, Q4: ≥200 mmHg 0.60 (0.51–0.69) <0.001 Delta SBP, Q4: ≥62 mmHg 0.59 (0.50–0.69) <0.001 SBP/MET slope, Q4: ≥9.1 1.40 (1.22– 1.62) <0.001 HR, hazard ratio (adjusted according to figure 1B); SBP, systolic blood pressure; MET, metabolic equivalent of task; Q1–Q4, quartiles (Q1 as reference).

Figure 1

Conclusion

Workload adjusted blood pressure response to exercise in contrast to peak BP response was associated with increased mortality in male patients referred for ET. Of note, reaching a BP of at least 210 mmHg (suggested to define a hypertensive response to exercise) was associated with a 24% reduction in all-cause mortality.

Acknowledgement/Funding

K Hedman was supported by post-doc. grants from the Fulbright Commission, the Swedish Society of Medicine, County Council of Östergötland, Sweden

ICAM-1 promotes the abnormal endothelial cell phenotype in chronic thromboembolic pulmonary hypertension

BACKGROUND

Pulmonary endothelial cells play a key role in the pathogenesis of Chronic Thromboembolic Pulmonary Hypertension (CTEPH). Increased synthesis and/or the release of intercellular adhesion molecule-1 (ICAM-1) by pulmonary endothelial cells of patients with CTEPH has been recently reported, suggesting a potential role for ICAM-1 in CTEPH.

METHODS

We studied pulmonary endarterectomy specimens from 172 patients with CTEPH and pulmonary artery specimens from 97 controls undergoing lobectomy for low-stage cancer without metastasis.

RESULTS

ICAM-1 was overexpressed in vitro in isolated and cultured endothelial cells from endarterectomy specimens. Endothelial cell growth and apoptosis resistance were significantly higher in CTEPH specimens than in the controls (p < 0.001). Both abnormalities were abolished by pharmacological inhibition of ICAM-1 synthesis or activity. The overexpression of ICAM-1 contributed to the acquisition and maintenance of abnormal EC growth and apoptosis resistance via the phosphorylation of SRC, p38 and ERK1/2 and the overproduction of survivin. Regarding the ICAM-1 E469K polymorphism, the KE heterozygote genotype was significantly more frequent in CTEPH than in the controls, but it was not associated with disease severity among patients with CTEPH.

CONCLUSIONS

ICAM-1 contributes to maintaining the abnormal endothelial cell phenotype in CTEPH.

Right ventricular mitochondrial respiratory function in a piglet model of chronic pulmonary hypertension

OBJECTIVE

We aimed to assess the mitochondrial respiratory capacities in the right ventricle in the setting of ventricular remodeling induced by pressure overload.

METHODS

Chronic thromboembolic pulmonary hypertension was induced in 8 piglets over a 12-week period (chronic thromboembolic pulmonary hypertension model). Right ventricular remodeling, right ventricular function, and mitochondrial respiratory function were assessed at 3, 6, and 12 weeks after induction of pulmonary hypertension and were compared with sham animals (n = 5). Right ventricular cardiomyocytes and mitochondrial structure were studied in transmission electronic microscopy after 12 weeks.

RESULTS

As of 3 weeks, chronic pressure overload induced right ventricular dilatation, right ventricular hypertrophy, and right ventricular dysfunction. Maladaptive remodeling in the chronic thromboembolic pulmonary hypertension model was confirmed by the decrease of right ventricular pulmonary artery coupling and right fractional area change. Mitochondrial functional assays in permeabilized right ventricular myocardial fibers revealed that oxidative phosphorylation capacities (complex I, complex II, and IV of the mitochondrial respiratory chain) were degraded. Furthermore, no change in substrate preference of mitochondria was found in the overloaded right ventricle. There was a good correlation between maximal mitochondrial oxygen consumption rate and right ventricular pulmonary artery coupling (Pearson coefficient r = 0.83). Transmission electronic microscopy analysis showed that the composition of cardiomyocytes was no different between the chronic thromboembolic pulmonary hypertension group and the sham group. However, mitochondrial structure anomalies were significantly increased in the chronic thromboembolic pulmonary hypertension group.

CONCLUSIONS

Mitochondrial respiratory function impairment is involved early in the development of right ventricular dysfunction in a piglet model of chronic thromboembolic pulmonary hypertension. Underlying mechanisms remain to be elucidated.

Pathophysiology of the right ventricle and of the pulmonary circulation in pulmonary hypertension: an update

The function of the right ventricle determines the fate of patients with pulmonary hypertension. Since right heart failure is the consequence of increased afterload, a full physiological description of the cardiopulmonary unit consisting of both the right ventricle and pulmonary vascular system is required to interpret clinical data correctly. Here, we provide such a description of the unit and its components, including the functional interactions between the right ventricle and its load. This physiological description is used to provide a framework for the interpretation of right heart catheterisation data as well as imaging data of the right ventricle obtained by echocardiography or magnetic resonance imaging. Finally, an update is provided on the latest insights in the pathobiology of right ventricular failure, including key pathways of molecular adaptation of the pressure overloaded right ventricle. Based on these outcomes, future directions for research are proposed.

State of the art and research perspectives in pathophysiology of the right ventricle and of the pulmonary circulation in pulmonary hypertension with theoretical and practical aspectshttp://ow.ly/18v830mgLiP