Obesity and pulmonary hypertension: a review of pathophysiologic mechanisms

Pulmonary arterial hypertension therapies in patients with obesity hypoventilation syndrome: a case series

Obesity hypoventilation syndrome is caused by complex interactions between multiple pathological processes, including diminished respiratory drive and sleep-related breathing alterations, leading to structural and functional respiratory impairment and ultimately, pulmonary hypertension. Because pulmonary hypertension is closely associated with obesity hypoventilation syndrome, thoroughly evaluating its etiology is essential, and individualized treatments must be considered. We describe 2 patients with obesity hypoventilation syndrome exhibiting severe pulmonary hypertension with pulmonary vascular resistance exceeding 5 Wood units; both were classified as Group 1 pulmonary hypertension, ie, pulmonary arterial hypertension. Initially admitted to our hospital complaining of dyspnea, both patients commenced pulmonary arterial hypertension therapies in addition to positive airway pressure therapy and diuretics, improving their hemodynamic status, dyspnea, and exercise capacity, and finally enabling their discharge. These findings suggest that pulmonary arterial hypertension can coexist with obesity hypoventilation syndrome, and pulmonary arterial hypertension therapies, introduced with careful consideration, may provide substantial benefits for select patients.

CITATION

Daigo K, Hiraide T, Momoi M, et al. Pulmonary arterial hypertension therapies in patients with obesity hypoventilation syndrome: a case series. J Clin Sleep Med. 2025;21(4):723-732.

Diagnosing Heart Failure with Preserved Ejection Fraction in Obese Patients

Obesity is a current pandemic that sets all affected individuals at risk of heart failure (HF), and the majority of them will develop the clinical syndrome of HF with preserved ejection fraction (HFpEF). The diagnosis of HFpEF is challenging as it is based on the detection of subtle functional and structural remodeling of the heart that leads to diastolic dysfunction with increased left ventricular (LV) filling pressures and raised natriuretic peptides (NPs). The accurate diagnosis of HFpEF is even more challenging in patients who are obese, since the echocardiographic imaging quality may be suboptimal, the parameters for the evaluation of cardiac structure are indexed to the body surface area (BSA) and thus may underestimate the severity of the remodeling, and the NPs in patients who are obese have a lower normal threshold. Moreover, patients who are obese are prone to atrial fibrillation (AF) and pulmonary hypertension (PH), making the evaluation of diastolic dysfunction more strenuous. The current review aims to offer insights on the accurate diagnosis of HFpEF in patients who are obese in different clinical scenarios-patients who are obese in different clinical scenarios-such as in sinus rhythm, in atrial fibrillation, and in the case of pulmonary hypertension-by applying multimodality imaging and clinical diagnostic algorithms.

Nonlinear effect of body mass index on postoperative survival following isolated heart transplantation

Background

Guidelines regarding recipient's body mass index (BMI) for heart transplant are evolving with variable cutoffs depending on the country and institution. It is imperative to provide updated nonlinear estimates of postoperative risk attributable to a recipient's BMI to evaluate the relevance of existing cutoffs.

Methods

A total of 30,787 patients were analyzed from the United Network for Organ Sharing (UNOS) database. Patients receiving an isolated heart transplant ages 18 and older since 2010 were included. Overall survival was the primary outcome. A multivariate Cox proportional hazards model was applied and included a penalized smoothing spline term for recipient BMI and risk factors such as diabetes. We assessed the overall significance of the nonlinear penalized spline terms using an asymptotic Wald test.

Results

The cohort consisted of 662 (2.2%) BMI <18.5, 9,359 (30%) BMI 18.5 to 24.9, 10,997 (36%) BMI 25 to 29.9, 9,550 (31%) BMI 30 to 39.9, and 206 (0.7%) BMI ≥40 patients. The nonlinear spline terms for recipient BMI were statistically significant (p < 0.01). The hazard ratio (HR) appeared to grow linearly in BMI at an inflection point of BMI = 26. No inflection point was observed at either of the International Society for Heart and Lung Transplantation recommended cutoffs of BMI = 30 (HR 1.11, confidence interval [CI] 1.07-1.15) or BMI = 35 (HR 1.29, CI 1.24-1.37).

Conclusions

After multivariable adjustment, there is no sharp cutoff in survival risk at either BMI = 30 or BMI = 35. Unlike previously reported, postoperative survival risk grows approximately linearly in the BMI range from 26 to 40.

Impact of Laparoscopic Sleeve Gastrectomy on Pulmonary Arterial Stiffness and Right Ventricular Function in Obese Patients

INTRODUCTION

Pulmonary hypertension (PH) is a serious condition associated with high morbidity and mortality, with obesity identified as a significant risk factor. Pulmonary arterial stiffness (PAS) is an early marker of PH, often preceding clinical symptoms. While laparoscopic sleeve gastrectomy (LSG) has been shown to improve various cardiac parameters in obese patients, its impact on PAS and right ventricular (RV) function in the absence of PH remains unclear. This study investigates the effects of LSG on PAS and RV function in obese patients without pre-existing PH.

METHODS

A cohort of 54 patients with obesity who underwent LSG between January and June 2023 at the University hospital was prospectively studied. Patients were evaluated preoperatively and six months postoperatively using comprehensive echocardiographic assessments. Key parameters measured included tricuspid annular systolic velocity (TAS), tricuspid regurgitation velocity (TRV), pulmonary flow acceleration time (PFAT), pulmonary artery velocity, and PAS. Statistical analyses were conducted using paired t-tests and the Wilcoxon signed-rank test.

RESULTS

Significant improvements were observed in several echocardiographic and hemodynamic parameters post-LSG. PAS showed a notable reduction from 2.44 ± 0.68 preoperatively to 1.74 ± 0.32 postoperatively (p < 0.001). Additionally, significant decreases were observed in TRV (2.00 ± 0.30 m/sec to 1.79 ± 0.40 m/sec, p = 0.025) and systolic pulmonary artery pressure (SPAP) (21.28 ± 4.69 mmHg to 18.36 ± 5.28 mmHg, p = 0.025). Improvements in RV function were indicated by an increase in tricuspid annular plane systolic excursion (TAPSE) from 17.68 ± 4.17 mm preoperatively to 21.18 ± 3.53 mm postoperatively (p < 0.001).

CONCLUSIONS

LSG significantly reduces PAS and improves RV function in obese patients, even in the absence of PH. These findings suggest that LSG may offer protective effects on pulmonary vascular health, highlighting its potential as a therapeutic intervention for reducing PH risk in obese patients. Further research is warranted to explore the long-term cardiovascular benefits of LSG in diverse populations.

Crosstalk Between the Spleen and Other Organs/Systems: Downstream Signaling Events

The aim of this review was to gather pieces of information from available critically evaluated published articles concerning any interplay in which the spleen could be involved. For many years, the spleen has been alleged as an unnecessary biological structure, even though splenomegaly is an objective finding of many illnesses. Indeed, the previous opinion has been completely changed. In fact, the spleen is not a passive participant in or a simple bystander to a relationship that exists between the immune system and other organs. Recently, it has been evidenced in many preclinical and clinical studies that there are close associations between the spleen and other parts of the body, leading to various spleen–organ axes. Among them, the gut–spleen axis, the liver–spleen axis, the gut–spleen–skin axis, the brain–spleen axis, and the cardio-splenic axis are the most explored and present in the medical literature. Such recent sources of evidence have led to revolutionary new ideas being developed about the spleen. What is more, these observations may enable the identification of novel therapeutic strategies targeted at various current diseases. The time has come to make clear that the spleen is not a superfluous body part, while health system operators and physicians should pay more attention to this organ. Indeed, much work remains to be performed to assess further roles that this biological structure could play.

Olanzapine-induced cardiomyopathy: A mimicker of obesity cardiomyopathy?

Olanzapine, an atypical antipsychotic medication, has gained prominence in the treatment of schizophrenia and related psychotic disorders due to its effectiveness and perceived safety profile. However, emerging evidence suggests a potential link between olanzapine use and adverse cardiovascular effects, including cardiomyopathy. This narrative review explores the mechanisms, clinical implications, and management strategies associated with olanzapine-induced cardiomyopathy. A comprehensive review of the literature was conducted to investigate the relationship between olanzapine and cardiomyopathy. The search included epidemiological studies, clinical case reports, and mechanistic research focusing on the pathophysiology of olanzapine-induced cardiomyopathy. The review also examined treatment strategies for managing this potential complication. Olanzapine-induced cardiomyopathy is hypothesized to be associated with metabolic disturbances and receptor antagonism. The metabolic effects of olanzapine, such as weight gain, insulin resistance, and dyslipidemia, share similarities with obesity-related cardiomyopathy. Additionally, olanzapine's antagonism of certain receptors may contribute to cardiovascular stress. The review highlighted that patients with new-onset heart failure and significant weight gain while on olanzapine should be closely monitored for signs of cardiomyopathy. Early detection and prompt withdrawal of olanzapine, along with initiation of goal-directed medical therapy, are crucial for mitigating this potentially life-threatening condition. The relationship between olanzapine and cardiomyopathy is complex and not yet fully understood. However, the potential for significant cardiovascular risk necessitates vigilance among healthcare providers. Early identification and management of olanzapine-induced cardiomyopathy can improve patient outcomes. Further research is needed to elucidate the precise mechanisms behind this adverse effect and to develop optimized treatment strategies for patients requiring antipsychotic therapy.

Pulmonary hypertension and insulin resistance: a mechanistic overview

Pulmonary arterial hypertension (PAH) is a vascular remodeling disease, characterized by increased blood pressure levels in pulmonary circulation, leading to a restriction in the circulation flow and heart failure. Although the emergence of new PAH therapies has increased survival rates, this disease still has a high mortality and patients that receive diagnosis die within a few years. The pathogenesis of PAH involves multiple pathways, with a complex interaction of local and distant cytokines, hormones, growth factors, and transcription factors, leading to an inflammation that changes the vascular anatomy in PAH patients. These abnormalities involve more than just the lungs, but also other organs, and between these affected organs there are different metabolic dysfunctions implied. Recently, several publications demonstrated in PAH patients a disturbance in glucose metabolism, demonstrated by higher levels of glucose, insulin, and lipids in those patients. It is possible that a common molecular mechanism can have a significant role in this connection. In this regard, this narrative review intends to focus on the recent papers that mainly discuss the molecular determinants between insulin resistance (IR) associated PAH, which included obesity subclinical inflammation induced IR, PPAR gamma and Adiponectin, BMPR2, mitochondrial dysfunction and endoplasmic reticulum stress. Therefore, the following review will summarize some of the existing data for IR associated PAH, focusing on the better understanding of PAH molecular mechanisms, for the development of new translational therapies.

Exploring the Mechanistic Link Between Obesity and Heart Failure

PURPOSE OF REVIEW

Among subtypes of cardiovascular disease, obesity has a potent and unique association with heart failure (HF) that is unexplained by traditional cardiovascular risk mediators. The concomitant rise in the prevalence of obesity and HF necessitates better understanding of their relationship to develop effective prevention and treatment strategies. The purpose of this review is to provide mechanistic insight regarding the link between obesity and HF by elucidating the direct and indirect pathways linking the two conditions.

RECENT FINDINGS

Several direct pathophysiologic mechanisms contribute to HF risk in individuals with excess weight, including hemodynamic alterations, neurohormonal activation, hormonal effects of dysfunctional adipose tissue, ectopic fat deposition with resulting lipotoxicity and microvascular dysfunction. Obesity further predisposes to HF indirectly through causal associations with hypertension, dyslipidemia, and most importantly, diabetes via insulin resistance. Low levels of physical activity and fitness further influence HF risk in the context of obesity. These various processes lead to myocardial injury and cardiac remodeling that are reflected by abnormalities in cardiac biomarkers and cardiac function on myocardial imaging. Understanding and addressing obesity-associated HF is a pressing clinical and public health challenge which can be informed by a deeper understanding of the complex pathways linking these two conditions together.

Paradoxical Shock and Management of a Post-percutaneous Mechanical Thrombectomy Device in a Morbidly Obese Patient With a Submassive Pulmonary Embolism

A submassive pulmonary embolism (PE) is a type of PE where the pulmonary artery is partially obstructed. It is categorized as an intermediate risk when compared to massive PE, which presents as a complete obstruction of the pulmonary artery, therefore placing it in the high-risk category. In either case, if not promptly assessed and treated, it can prove to be fatal. We report the case of a morbidly obese middle-aged female who presented with a submassive PE. Based on the evaluation of the patient's pre-existing conditions, risk factors, clinical severity, imaging, and lab findings, it was concluded that percutaneous mechanical thrombectomy (PMT) was essential to promptly alleviate the clot burden. Following the procedure, it was observed that the patient became hemodynamically unstable, accompanied by hypoxemia and respiratory acidosis. With the assistance of pressors and later the placement of a right ventricular Impella device, the patient was successfully stabilized and, several days later, discharged from the hospital. This report explores the potential factors that may have contributed to the patient's hemodynamic instability and acute right ventricular failure after the PMT procedure. These factors can be attributed to pre-existing changes in the right ventricle (RV) as a result of morbid obesity, as well as possible associations with obstructive sleep apnea or obesity hypoventilation syndrome. Furthermore, it is important to highlight that patients exhibiting submassive PE can be considered suitable candidates for PMT, with careful consideration of the patient's medical history, clinical severity of symptoms, and diagnostic findings. It is worth noting that PMT intervention in this patient demonstrated a favorable outcome.

Impact of malnutrition on prognosis in patients with pulmonary arterial hypertension

Pulmonary arterial hypertension is a life-threatening disease that coexists with right heart failure. We evaluated the relationship between malnutrition and prognosis in patients with pulmonary arterial hypertension, as malnutrition is known as a prognosis determinant in chronic heart failure. We retrospectively reviewed data of patients with pulmonary arterial hypertension before treatment. The Geriatric Nutritional Risk Index, Prognostic Nutritional Index, and Controlling Nutritional Status scores on the day of diagnosis were calculated to assess the nutritional status. Clinical endpoints were defined as composite outcomes of all-cause death or lung transplantation. Eighty patients were enrolled (mean age, 50 years; 23 men). The mean pulmonary arterial pressure was 47 ± 19 mmHg, Geriatric Nutritional Risk Index was 99.9 ± 12.0, and Prognostic Nutritional Index was 46.3 ± 10.0. The median Controlling Nutritional Status score was 2 (1-4). During the median 5.5-year follow-up period, 28 composite events occurred. Kaplan-Meier analysis demonstrated significant differences in the incidence of clinical endpoints between groups divided by each median Geriatric Nutritional Risk Index, Prognostic Nutritional Index, and Controlling Nutritional Status score (p = 0.007, 0.039, and 0.010, respectively). In multivariate Cox regression analysis, clinical endpoints were significantly associated with Geriatric Nutritional Risk Index (hazard ratio: 0.953, 95% confidence interval: 0.918-0.990), Prognostic Nutritional Index (hazard ratio: 0.942, 95% confidence interval: 0.892-0.996), and Controlling Nutritional Status score (hazard ratio: 1.230, 95% confidence interval: 1.056-1.433) after adjustment for factors associated in univariate Cox regression analysis. Malnutrition at diagnosis is a useful prognostic predictor for patients with pulmonary arterial hypertension.

Respiratory complications of obesity: from early changes to respiratory failure

Obesity is a significant and increasingly common cause of respiratory compromise. It causes a decrease in static and dynamic pulmonary volumes. The expiratory reserve volume is one of the first to be affected. Obesity is associated with reduced airflow, increased airway hyperresponsiveness, and an increased risk of developing pulmonary hypertension, pulmonary embolism, respiratory tract infections, obstructive sleep apnoea and obesity hypoventilation syndrome. The physiological changes caused by obesity will eventually lead to hypoxic or hypercapnic respiratory failure. The pathophysiology of these changes includes a physical load of adipose tissue on the respiratory system and a systemic inflammatory state. Weight loss has clear, well-defined benefits in improving respiratory and airway physiology in obese individuals.

Impact of Rapid Weight Loss after Bariatric Surgery in Systemic Inflammatory Response and Pulmonary Hemodynamics in Severely Obese Subjects with Pulmonary Hypertension

BACKGROUND

Pulmonary hypertension (PH) can be associated with obesity. The excessive production of proinflammatory mediators by dysfunctional adipocytes may enhance remodeling of the pulmonary vasculature and worsen pulmonary hemodynamics. This study aimed to describe the changes in pulmonary arterial pressures and systemic inflammation in patients with obesity with PH after bariatric surgery (BaS).

STUDY DESIGN

In this retrospective cohort study, we compared patients with PH who underwent BaS from 2008 to 2018 at our institution (group 1) to a group of severely obese patients with PH (group 2). Echocardiographic right ventricular systolic pressure (RVSP) was used as an indirect measurement of pulmonary arterial pressures. Red blood cell distribution width (RDW) was used as a marker of systemic inflammation.

RESULTS

A total of 40 patients were included, 20 per group. In group 1, the RVSP decreased from 44.69 ± 7.12 mmHg to 38.73 ± 12.81 mmHg (p = 0.041), and the RDW decreased from 15.22 ± 1.53 to 14.41 ± 1.31 (p = 0.020). In group 2, the RVSP decreased from 60.14 ± 18.08 to 59.15 ± 19.10 (0.828), and the RDW increased from 15.37 ± 1.99 to 15.38 ± 1.26 (0.983). For both groups, we found a positive correlation between RVSP and RDW changes, although the correlation was not statistically significant.

CONCLUSIONS

Previous studies suggest BaS could be a safe and effective procedure to achieve weight loss in obese patients with PH, with an additional modest improvement in pulmonary hemodynamics. The results of this study reinforce this observation and suggest that such improvement could be related to a decrease in systemic inflammation. Further prospective studies with bigger samples are needed to better understand these findings.

Pre-operative screening for sleep disordered breathing: obstructive sleep apnoea and beyond

Sleep disordered breathing describes an important group of conditions that causes abnormal nocturnal gas exchange, with important implications in the peri-operative management plan. An understanding of the pathophysiology behind obstructive sleep apnoea and other disorders that may lead to hypoventilation can help to prevent complications. Patients with these disorders may be minimally symptomatic and it requires careful screening in the pre-operative assessment process for a diagnosis to be made. Decisions regarding initiation of therapy, such as positive airway pressure, and delay of the operation need to be carefully weighed up against the urgency of the surgical intervention. Planning of the peri-operative care, including the use of positive airway pressure therapy and appropriate post-operative monitoring, can help to avoid respiratory and cardiovascular morbidities and improve clinical outcomes.

Educational aims

To review different types of sleep disordered breathing and available screening methods in pre-operative assessment.To understand the pathophysiology behind sleep disordered breathing and how it can lead to complications in the peri-operative setting.To review the planning and treatment strategies that should be considered as part of peri-operative management.

Comorbidities and laboratory parameters associated with SARS-CoV-2 infection severity in patients from the southeast of Mexico: a cross-sectional study

Background. Severe acute respiratory syndrome-coronavirus 2 (SARS-CoV-2) is the etiological agent of the coronavirus disease 2019 (COVID-19) pandemic. Among the risk factors associated with the severity of this disease is the presence of several metabolic disorders. For this reason, the aim of this research was to identify the comorbidities and laboratory parameters among COVID-19 patients admitted to the intensive care unit (ICU), comparing the patients who required invasive mechanical ventilation (IMV) with those who did not require IMV, in order to determine the clinical characteristics associated with the COVID-19 severity.

Methods. We carried out a cross-sectional study among 152 patients who were admitted to the ICU from April 1 ^st to July 31 ^st, 2021, in whom the comorbidities and laboratory parameters associated with the SARS-CoV-2 infection severity were identified. The data of these patients was grouped into two main groups: “patients who required IMV” and “patients who did not require IMV”. The nonparametric Mann–Whitney U test for continuous data and the χ2 test for categorical data were used to compare the variables between both groups.

Results. Of the 152 COVID-19 patients who were admitted to the ICU, 66 required IMV and 86 did not require IMV. Regarding the comorbidities found in these patients, a higher prevalence of type 2 diabetes mellitus (T2DM), hypertension and obesity was observed among patients who required IMV vs. those who did not require IMV ( p<0.05). Concerning laboratory parameters, only glucose, Interleukin 6 (IL-6), lactate dehydrogenase (LDH) and C-reactive protein (CRP) were significantly higher among patients who required IMV than in those who did not require IMV ( p<0.05).

Conclusion. This study performed in a Mexican population indicates that comorbidities such as: T2DM, hypertension and obesity, as well as elevated levels of glucose, IL-6, LDH and CRP are associated with the COVID-19 severity.

The substitution of SERCA2 redox cysteine 674 promotes pulmonary vascular remodeling by activating IRE1α/XBP1s pathway

Pulmonary hypertension (PH) is a life-threatening disease characterized by pulmonary vascular remodeling, in which hyperproliferation of pulmonary artery smooth muscle cells (PASMCs) plays an important role. The cysteine 674 (C674) in the sarcoplasmic/endoplasmic reticulum Ca²⁺ ATPase 2 (SERCA2) is the critical redox regulatory cysteine to regulate SERCA2 activity. Heterozygous SERCA2 C674S knock-in mice (SKI), where one copy of C674 was substituted by serine to represent partial C674 oxidative inactivation, developed significant pulmonary vascular remodeling resembling human PH, and their right ventricular systolic pressure modestly increased with age. In PASMCs, substitution of C674 activated inositol requiring enzyme 1 alpha (IRE1α) and spliced X-box binding protein 1 (XBP1s) pathway, accelerated cell cycle and cell proliferation, which reversed by IRE1α/XBP1s pathway inhibitor 4μ8C. In addition, suppressing the IRE1α/XBP1s pathway prevented pulmonary vascular remodeling caused by substitution of C674. Similar to SERCA2a, SERCA2b is also important to restrict the proliferation of PASMCs. Our study articulates the causal effect of C674 oxidative inactivation on the development of pulmonary vascular remodeling and PH, emphasizing the importance of C674 in restricting PASMC proliferation to maintain pulmonary vascular homeostasis. Moreover, the IRE1α/XBP1s pathway and SERCA2 might be potential targets for PH therapy.

The Role of Thyroid Disorders, Obesity, Diabetes Mellitus and Estrogen Exposure as Potential Modifiers for Pulmonary Hypertension

Pulmonary hypertension (PH) is a progressive disorder characterized by a chronic in-crease in pulmonary arterial pressure, frequently resulting in right-sided heart failure and potentially death. Co-existing medical conditions are important factors in PH, since they not only result in the genesis of the disorder, but may also contribute to its progression. Various studies have assessed the impact of thyroid disorders and other endocrine conditions (namely estrogen exposure, obesity, and diabetes mellitus) on the progression of PH. The complex interactions that hormones may have with the cardiovascular system and pulmonary vascular bed can create several pathogenetic routes that could explain the effects of endocrine disorders on PH development and evolution. The aim of this review is to summarize current knowledge on the role of concomitant thyroid disorders, obesity, diabetes mellitus, and estrogen exposure as potential modifiers for PH, and especially for pulmonary arterial hypertension, and to discuss possible pathogenetic routes linking them with PH. This information could be valuable for practicing clinicians so as to better evaluate and/or treat concomitant endocrine conditions in the PH population.

The Association of Body Mass Index With the Risk of Pulmonary Hypertension in Adults: A Systematic Review and Meta-Analysis of Observational Studies

Backgrounds

Findings regarding the association of body mass index (BMI) with pulmonary hypertension (PH) are conflicting, and there is no systematic review and meta-analysis to summarize the results. Therefore, the purpose of this systematic review and meta-analysis is to assess this relationship.

Methods

To detect the relevant articles, PubMed, Scopus, and Google Scholar were searched until February 2021. Included essays were pooled using a random-effect model. Cochrane Q-test and I²-test was applied to assess between-study heterogeneity.

Results

Fourteen articles (eight cross-sectional and four cohort studies) were included in the meta-analysis. The meta-analysis of comparing highest vs. lowest BMI categories did not indicate a significant association between BMI and PH (Summary Effect Estimate: 1.59 (95% CI: 0.50, 5.07, I² = 92.3). Furthermore, The summary risk estimate for a one-unit increment in BMI was 1.01 (95 % CI: 0.99, 1.03), with high heterogeneity, I² = 73.5 %, P heterogeneity <0.001). Subgroup analysis showed significant positive association between BMI and the risk of PH in studies controlled for cofounders, and studies with higher sample sizes (≥2,000).

Conclusion

There is no significant association between BMI and risk of pulmonary hypertension. Further studies are required to confirm these findings.

Impact of Obesity on Heart Transplantation Outcomes

Background

Patients with obesity and advanced heart failure face unique challenges on the path to heart transplantation. There are limited data on waitlist and transplantation outcomes in this population. We aimed to evaluate the impact of obesity on heart transplantation outcomes, and to investigate the effects of the new organ procurement and transplantation network allocation system in this population.

Methods and Results

This cohort study of adult patients listed for heart transplant used the United Network for Organ Sharing database from January 2006 to June 2020. Patients were stratified by body mass index (BMI) (18.5–24.9, 25–29.9, 30–34.9, 35–39.9, and 40–55 kg/m²). Recipient characteristics and donor characteristics were analyzed. Outcomes analyzed included transplantation, waitlist death, and posttransplant death. BMI 18.5 to 24.9 kg/m² was used as the reference compared with progressive BMI categories. There were 46 645 patients listed for transplantation. Patients in higher BMI categories were less likely to be transplanted. The lowest likelihood of transplantation was in the highest BMI category, 40 to 55 kg/m² (hazard ratio [HR], 0.19 [0.05–0.76]; P=0.02). Patients within the 2 highest BMI categories had higher risk of posttransplantation death (HR, 1.29; P<0.001 and HR, 1.65; P<0.001, respectively). Left ventricular assist devices among patients in obese BMI categories decreased after the allocation system change (P<0.001, all). After the change, patients with obesity were more likely to undergo transplantation (BMI 30–35 kg/m²: HR, 1.31 [1.18–1.46], P<0.001; BMI 35–55 kg/m²: HR, 1.29 [1.06–1.58]; P=0.01).

Conclusions

There was an inverse relationship between BMI and likelihood of heart transplantation. Higher BMI was associated with increased risk of posttransplant mortality. Patients with obesity were more likely to undergo transplantation under the revised allocation system.

Positionspapier „Schlafmedizin in der Kardiologie“, Update 2021

Es hat sich viel getan in der Welt der Schlafmedizin in der Kardiologie, weshalb eine vollwertige Überarbeitung des Positionspapiers „Schlafmedizin in der Kardiologie“ erforderlich wurde. In der aktuellen neuartigen Version finden sich nicht nur alle verfügbaren Studien, Literaturstellen und Updates zu Pathophysiologie, Diagnostik- und Therapieempfehlungen, sondern auch Ausblicke auf neue Entwicklungen und zukünftige Forschungserkenntnisse. Dieses überarbeitete Positionspapier gibt Empfehlungen für Diagnostik und Therapie von Patienten mit kardiovaskulären Erkrankungen mit schlafassoziierten Atmungsstörungen und erteilt darüber hinaus einen fundierten Überblick über verfügbare Therapien und Evidenzen, gibt aber ebenso Ratschläge wie mit Komorbiditäten umzugehen ist. Insbesondere enthält dieses überarbeitete Positionspapier aktualisierte Stellungnahmen zu schlafassoziierten Atmungsstörungen bei Patienten mit koronarer Herzerkrankung, Herzinsuffizienz, arterieller Hypertonie, aber auch für Patienten mit Vorhofflimmern. Darüber hinaus finden sich erstmals Empfehlungen zur Telemedizin als eigenes, neues Kapitel. Dieses Positionspapier bietet Kardiologen sowie Ärzten in der Behandlung von kardiovaskulären Patienten die Möglichkeit einer evidenzbasierten Behandlung der wachsend bedeutsamen und mit zunehmender Aufmerksamkeit behafteten Komorbidität schlafassoziierter Atmungsstörungen. Und nicht zuletzt besteht mit diesem neuen Positionspapier eine enge Verknüpfung mit dem neuen Curriculum Schlafmedizin der Deutschen Gesellschaft für Kardiologie, weshalb dieses Positionspapier eine Orientierung für die erworbenen Fähigkeiten des Curriculums im Umgang von kardiovaskulären Patienten mit schlafassoziierten Atmungsstörungen darstellt.

Cardiovascular disease in obesity hypoventilation syndrome - A review of potential mechanisms and effects of therapy

Cardiovascular disease is common in patients with obesity hypoventilation syndrome (OHS) and accounts in part for their poor prognosis. This narrative review article examines the epidemiology of cardiovascular disease in obesity hypoventilation syndrome, explores possible contributing factors and the effects of therapy. All studies that included cardiovascular outcomes and biomarkers were included. Overall, there is a higher burden of cardiovascular disease and cardiovascular risk factors among patients with obesity hypoventilation syndrome. In addition to obesity and sleep-disordered breathing, there are several other pathophysiological mechanisms that contribute to higher cardiovascular morbidity and mortality in OHS. There is evidence emerging that positive airway pressure therapy and weight loss have beneficial effects on the cardiovascular system in obesity hypoventilation syndrome patients, but further research is needed to clarify whether this translates to clinically important outcomes.

Pulmonary Artery Dilatation Is a Common Finding in a Coronary Artery CT Angiography Population

BACKGROUND/AIM

Dilatation of the main pulmonary artery (mPA) is a common incidental finding in chest imaging and often leads to consultation. The aim of this study was to determine the prevalence of mPA dilatation in a coronary artery CT angiography (CCTA) population.

PATIENTS AND METHODS

The study investigated 985 consecutive patients scheduled for diagnostic CCTA. The transverse axial diameter of the mPA was measured. The prevalence of mPA dilatation was estimated using different reference values (Framingham Heart Study: 28.9 mm for males and 26.9 mm for females, Bozlar: 29.5 mm for both genders and Karazincir: 32.6 mm for males and 31.9 mm for females).

RESULTS

The patient mean age was 53.0±9.7 years (66.5% were women). Body surface area (BSA) correlated moderately with the mPA diameter (r=0.423, p<0.001). The prevalence of mPA dilatation varied from 5.9% (Karazincir) to 33.7% (Framingham Heart Study) in the overall study population.

CONCLUSION

The prevalence of mPA dilatation is high in a CCTA patient population when using a cut-off value from the Framingham Heart Study.

Obesity cardiomyopathy: evidence, mechanisms, and therapeutic implications

The prevalence of heart failure is on the rise and imposes a major health threat, in part, due to the rapidly increased prevalence of overweight and obesity. To this point, epidemiological, clinical, and experimental evidence supports the existence of a unique disease entity termed “obesity cardiomyopathy,” which develops independent of hypertension, coronary heart disease, and other heart diseases. Our contemporary review evaluates the evidence for this pathological condition, examines putative responsible mechanisms, and discusses therapeutic options for this disorder. Clinical findings have consolidated the presence of left ventricular dysfunction in obesity. Experimental investigations have uncovered pathophysiological changes in myocardial structure and function in genetically predisposed and diet-induced obesity. Indeed, contemporary evidence consolidates a wide array of cellular and molecular mechanisms underlying the etiology of obesity cardiomyopathy including adipose tissue dysfunction, systemic inflammation, metabolic disturbances (insulin resistance, abnormal glucose transport, spillover of free fatty acids, lipotoxicity, and amino acid derangement), altered intracellular especially mitochondrial Ca²⁺ homeostasis, oxidative stress, autophagy/mitophagy defect, myocardial fibrosis, dampened coronary flow reserve, coronary microvascular disease (microangiopathy), and endothelial impairment. Given the important role of obesity in the increased risk of heart failure, especially that with preserved systolic function and the recent rises in COVID-19-associated cardiovascular mortality, this review should provide compelling evidence for the presence of obesity cardiomyopathy, independent of various comorbid conditions, underlying mechanisms, and offer new insights into potential therapeutic approaches (pharmacological and lifestyle modification) for the clinical management of obesity cardiomyopathy.

Obstructive Sleep Apnea and Pulmonary Hypertension: A Review of Literature

Obstructive sleep apnea (OSA) is a disease process involving recurrent pharyngeal collapse during sleep, resulting in apneic episodes. Clinically, symptoms can include snoring, sudden awakening with a choking-like sensation, excessive somnolence, non-restorative sleep, difficulty in starting or maintaining sleep, and fatigue. It results in impaired gas exchange, subsequently causing various cardiovascular, metabolic, and neurocognitive pathologies. Historically, OSA has been underdiagnosed and undertreated, especially in women.

OSA is associated with WHO (World Health Organization) class III pulmonary hypertension (PH) or PH due to lung disease. PH is a concerning complication of OSA and thought to occur in roughly 20% of individuals with OSA. The pathogenesis of PH in OSA can include pulmonary artery vasoconstriction and remodeling. Patients suffering from OSA who develop PH tend to have worse cardiovascular and pulmonary changes. We present a thorough review of the literature examining the interplay between OSA and PH.

Adipokines and Metabolic Regulators in Human and Experimental Pulmonary Arterial Hypertension

Pulmonary hypertension (PH) is associated with meta-inflammation related to obesity but the role of adipose tissue in PH pathogenesis is unknown. We hypothesized that adipose tissue-derived metabolic regulators are altered in human and experimental PH. We measured circulating levels of fatty acid binding protein 4 (FABP-4), fibroblast growth factor -21 (FGF-21), adiponectin, and the mRNA levels of FABP-4, FGF-21, and peroxisome proliferator-activated receptor γ (PPARγ) in lung tissue of patients with idiopathic PH and healthy controls. We also evaluated lung and adipose tissue expression of these mediators in the three most commonly used experimental rodent models of pulmonary hypertension. Circulating levels of FABP-4, FGF-21, and adiponectin were significantly elevated in PH patients compared to controls and the mRNA levels of these regulators and PPARγ were also significantly increased in human PH lungs and in the lungs of rats with experimental PH compared to controls. These findings were coupled with increased levels of adipose tissue mRNA of genes related to glucose uptake, glycolysis, tricarboxylic acid cycle, and fatty acid oxidation in experimental PH. Our results support that metabolic alterations in human PH are recapitulated in rodent models of the disease and suggest that adipose tissue may contribute to PH pathogenesis.

The Influence of Obesity on Treatment and Outcome of Severely Burned Patients

Obesity and the related medical, social, and economic impacts are relevant multifactorial and chronic conditions that also have a meaningful impact on outcomes following a severe injury, including burns. In addition to burn-specific difficulties, such as adequate hypermetabolic response, fluid resuscitation, and early wound coverage, obese patients also present with common comorbidities, such as arterial hypertension, diabetes mellitus, or nonalcoholic fatty liver disease. In addition, the pathophysiologic response to severe burns can be enhanced. Besides the increased morbidity and mortality compared to burn patients with normal weight, obese patients present a challenge in fluid resuscitation, perioperative management, and difficulties in wound healing. The present work is an in-depth review of the current understanding of the influence of obesity on the management and outcome of severe burns.

Relationship between Pulmonary Artery Diameter and Pulmonary to Aortic Artery Diameter Ratio in High Risk Individuals for Obstructive Sleep Apnea without Pulmonary Artery Hypertension Based on the Berlin Questionnaire

BACKGROUND

A significant association has been found between the pulmonary artery (PA) diameter and obstructive sleep apnea (OSA) in patients with pulmonary artery hypertension (PAH). We aimed to evaluate the relationship between the diameters of the PA trunk and aortic artery with their ratio as PAH markers in high risk cases for OSA based on the Berlin questionnaire without PAH.

MATERIALS AND METHODS

This case-control study included 161 non-PAH patients admitted to a multi-slice CT scan ward. Filling out the Berlin questionnaire, the patients were divided into high and low risk cases for OSA. The diameters of the PA trunk and aortic ascending aorta and their ratio were assessed using the multi-slice CT scan.

RESULTS

The PA to aortic ratios in the case and control groups were 0.89±0.17 and 0.88±0.17, respectively, which all were non-significant. With regard to gender, the PA diameter was significantly lower among males in the control group than in the case group (P=0.034). The mean PA to aortic ratio was slightly higher but statistically non-significant in the case group than in the control group. The aortic diameter showed a statistically significant increase by age in the case group (r=0.374, P=0.003) compared to the other group. However, the PA diameter increased significantly by age in both groups (r=0.184, P=0.020).

CONCLUSION

The PA diameter can be considered as a predicting factor for future cardiovascular diseases in high risk males for OSA based on the Berlin questionnaire without PAH. More studies are required to confirm these findings.

Hypoxemia and pulmonary hypertension in patients with concomitant restrictive ventilatory defect and sleep apnea: the overlap syndrome

BACKGROUND

To investigate the severity of hypoxemia and prevalence of pulmonary hypertension (PHTN) in patients with the overlap syndrome (OS) of restrictive ventilatory defect (RVD) and sleep apnea (SA).

METHODS

Patients referred for both sleep test and spirometry for suspected SA and ventilatory disorders were recruited prospectively from January 2019 to January 2020. SA was determined by an apnea-hypopnea index ≥ 5/h; average oxygen saturation during sleep (meanSaO₂) and percentage of total sleep time with saturation < 90% (T90) were calculated. RVD was diagnosed in the presence of forced expiratory volume in the first second/forced vital capacity (FVC) > 0.7 and FVC < 80% predicted value. PHTN was defined by tricuspid regurgitation peak velocity ≥ 3.4 m/s, documented by noninvasive transthoracic echocardiography.

RESULTS

Patients with OS had significantly lower meanSaO₂ but higher T90 than subjects with isolated SA and isolated RVD. Patients with OS vs. those with isolated SA had higher odds of PHTN in multivariable analysis with age, sex, and body mass index adjusted for (OR 2.96, 95%CI 1.05-8.91, p = 0.040). Patients with meanSaO₂ < 92% vs. meanSaO₂ ≥ 92% had significantly higher odds of being diagnosed with PHTN (OR 5.40, 95%CI 2.01-15.7, p < 0.001). Similarly, T90 (≥ 4.5% versus < 4.5%) was also independently associated with the prevalence of PHTN (OR 7.21, 95%CI 2.54-23.67, p < 0.001).

CONCLUSION

Patients with OS of RVD and SA had severe hypoxemia, which is associated with the prevalence of PHTN. Further investigation is needed to discern whether therapeutic strategies toward OS might mitigate PHTN in this cohort.

TRIAL REGISTRATION

Clinical Trial Registration No. ChiCTR1900027294 on 1 October 2019.

Association of Pulmonary Hypertension With End-Stage Renal Disease Among the Obese Population

Introduction

Pulmonary hypertension (PH) is a known complication that occurs in patients of end-stage renal disease (ESRD) that have an arteriovenous fistula (AVF) for hemodialysis (HD). It is defined as pulmonary artery pressure (PAP) of greater than 30 mmHg on echocardiography. The presence of PH in ESRD is an independent risk factor and decreases the survival likelihood among HD patients. Unexplained PH is frequently seen in ESRD following AVF.

Obesity can lead to various complications, such as sleep apnea, cardiac complications, pulmonary hypertension, and mortality. Data on the prevalence of coexisting PH and obesity are scarce.

Obese patients often have increased albumin excretion rates (AER) that can lead to early renal impairment and an increase in intraglomerular pressure, which may increase the risk of cardiovascular (CV) morbidity and mortality.

Therefore, the study aimed to evaluate and compare the associated PH and obesity separately and collectively among ESRD patients.

Methods

This comparative cross-sectional study was conducted in a tertiary care public sector hospital with the approval of the medical ethics review board committee.

The study enrolled all consecutive patients with ESRD as defined by having an estimated glomerular filtration rate (GFR) of <15 mL/min/1.7 3 m² from April 2017 till March 2019, who presented to our facility. These patients underwent dialysis twice or thrice a week, each session lasting three to four hours approximately. On initial encounter, trans-thoracic echocardiography (TTE) was done by the cardiologist to diagnose pulmonary hypertension.

In addition, body mass index (BMI) was calculated for all patients, and the patients were categorized into underweight, normal, overweight, or obese. All patients underwent post-dialysis TTE at one hour or when patients were at the optimal dry weight. Systolic PAP and ejection fraction were measured, and pulmonary hypertension was defined as a PAP of 30 mmHg or greater on TTE.

ESRD patients that were diagnosed with PH prior to hemodialysis or had primary PH were excluded from the study. Only ESRD patients developing secondary PH after hemodialysis were included in the study.

The chi-square test was used to see the correlation of gender, ambulation status, smoking status, obesity, pulmonary hypertension, body mass index (BMI), and pulmonary hypertension and obesity combined on the final outcome. A p-value of 0.05 was considered significant. Odds ratio (OR) and relative risk (RR) were calculated for pulmonary hypertension and obesity combined, obesity, and pulmonary hypertension in the final outcome.

Results

The study enrolled 204 patients with a mean age of 46.23 (±20.45 SD) having higher female participation of 108 (52.9%), whereas 96 (47.1%) were males. The average weight of the cohort was 66.78 kg (±22.98 SD) with a mean BMI of 29.91 kg/m² (±13.29SD), 52 (25.5%) patients were underweight, 40 (19.6%) had a normal BMI, 29 (14.2%) were overweight, and 83 (40.7%) patients were obese.

Pulmonary hypertension and obesity combined were observed in 48 (23.5%) of the cases and there was a 4.60 relative risk of death among these individuals, with an odds ratio of 13.35 and a p-value of 0.00.

Conclusion

The study shows a strong synergistic effect of pulmonary hypertension and obesity towards the final survival outcome in ESRD patients who are on hemodialysis.

Pulmonary embolism in obesity-hypoventilation syndrome

INTRODUCTION

Obesity-hypoventilation syndrome occurs with alveolar hypoventilation during sleeping and daytime. Obesity may be a risk factor for venous thromboembolism. However, the venous thromboembolism in the obesity-hypoventilation syndrome is not well characterized.

OBJECTIVE

This case series aimed to investigate the presence and clinical features of venous thromboembolism in patients with the obesity-hypoventilation syndrome.

METHODS

Data of eight case reports were collected. Ages ranged from 36 to 73 years.

RESULTS

All patients had mosaic perfusion and enlarged main pulmonary artery, two had signs of infarction and mostly segmental and subsegmental filling defects. On the basis of this information some conclusions can be drawn carefully.

CONCLUSION

Present cases indicate that pulmonary embolism are also very common in patients with obesity-hypoventilation syndrome, anticoagulant therapy is at least as important as the treatment of the current disease. Clinicians will frequently be faced with patients with obesity-hypoventilation syndrome suspected of PE.

Chemerin Added to Endothelin-1 Promotes Rat Pulmonary Artery Smooth Muscle Cell Proliferation and Migration

Background

While chemerin has been shown to increase proliferation and migration of systemic vascular smooth muscle cells (SMCs) contributing therefore to the development of hypertension, this remains to be clarified for the pulmonary circulation.

Methods

Expression of chemerin and its three receptors (CMKRL1, CCRL2, GPR1) was examined by immunohistochemistry and RTq-PCR in lungs, pulmonary artery, and thoracic aorta from Wistar rats. Primary cultured rat pulmonary artery and thoracic aorta SMCs treated with recombinant chemerin (tested from 5.10^–9 to 10^–7 mol/L) were assessed for proliferation and migration (both with 10^–7 mol/L endothelin-1), as well as for staurosporine-induced apoptosis.

Results

In pulmonary artery and thoracic aorta, CMKLR1 expression was detected in both endothelial cells and SMCs. In primary cultured pulmonary artery SMCs, chemerin and its three receptors were expressed, and CMKLR1 expression was higher than those of CCRL2 and GPR1. Chemerin added to endothelin-1 increased pulmonary artery SMC proliferation, while chemerin or endothelin-1 alone did not. This effect was less pronounced in thoracic aorta SMCs. Chemerin induced pulmonary artery and thoracic aorta SMC migration, which was exacerbated by endothelin-1 and more pronounced in thoracic aorta SMCs. Chemerin concentration-dependently reduced staurosporine-induced apoptosis in both pulmonary artery and thoracic aorta SMCs. In pulmonary artery SMCs, endothelin-1 treatment increased the expression of CMKLR1, CCRL2, and GPR1, while these expressions were not altered in thoracic aorta SMCs.

Conclusion

Chemerin/CMKRL1 signaling, in conjunction with a key mediator in the pathogenesis of pulmonary hypertensive diseases, endothelin-1, stimulated proliferation and migration, and increased resistance to apoptosis in rat primary cultured pulmonary artery SMCs. Our results suggest that this signaling could play a role in pulmonary artery remodeling observed in pulmonary hypertension.

BMI Is Causally Associated With Pulmonary Artery Pressure But Not Hemodynamic Evidence of Pulmonary Vascular Remodeling

BACKGROUND

There is an unclear relationship of obesity to the pathogenesis and severity of pulmonary arterial hypertension (PAH) and pulmonary venous hypertension (PVH).

RESEARCH QUESTION

Is BMI casually associated with pulmonary artery pressure (PAP) and/or markers of pulmonary vascular remodeling?

STUDY DESIGN AND METHODS

The study design was a two-sample inverse-variance weighted Mendelian randomization. We constructed two BMI genetic risk scores from genome-wide association study summary data and deployed them in nonoverlapping cohorts of subjects referred for right heart catheterization (RHC) or echocardiography. A BMI highly polygenic risk score (hpGRS) optimally powered to detect shared genetic architecture of obesity with other traits was tested for association with RHC parameters including markers of pulmonary vascular remodeling. A BMI strict genetic risk score (sGRS) composed of high-confidence genetic variants was used for Mendelian randomization analyses to assess if higher BMI causes higher PAP.

RESULTS

Among all subjects, both directly measured BMI and hpGRS were positively associated with pulmonary arterial pressures but not markers of pulmonary vascular remodeling. Categorical analyses revealed BMI and hpGRS were associated with PVH but not PAH. Mendelian randomization of the sGRS supported that higher BMI is causal of higher systolic pulmonary artery pressure (sPAP). Sensitivity analyses showed sPAP-BMI sGRS relationship was preserved when either individuals with PAH or PVH were excluded. In the echocardiographic cohort, BMI and hpGRS were positively associated with estimated PAP and markers of left heart remodeling.

INTERPRETATION

BMI is a modifier of pulmonary hypertension severity in both PAH and PVH but is only involved in the pathogenesis of PVH.

Vascular Metabolic Mechanisms of Pulmonary Hypertension

Pulmonary hypertension (PH) is a severe and progressive disease characterized by increased pulmonary vascular resistance leading to right heart failure and death. In PH, the cellular metabolisms including those of the three major nutrients (carbohydrate, lipid and protein) are aberrant in pulmonary vascular cells. Glucose uptake, glycolysis, insulin resistance, sphingolipid S1P, PGE₂, TXA₂, leukotrienes and glutaminolysis are upregulated, and phospholipid-prostacyclin and L-arginine-nitric oxide pathway are compromised in lung vascular cells. Fatty acid metabolism is disordered in lung endothelial cells and smooth muscle cells. These molecular mechanisms are integrated to promote PH-specific abnormal vascular cell proliferation and vascular remodeling. This review summarizes the recent advances in the metabolic reprogramming of glucose, fatty acid, and amino acid metabolism in pulmonary vascular remodeling in PH and the mechanisms for how these alterations affect vascular cell fate and impact the course of PH.

Long-term outcome with focus on pulmonary hypertension in Obesity Hypoventilation Syndrome

INTRODUCTION

Pulmonary Hypertension (PH) is a frequent comorbidity in Obesity Hypoventilation Syndrome (OHS).

OBJECTIVE

We investigated long-term outcome of OHS with a particular emphasis on PH.

METHODS

In a prospective design, 64 patients with OHS and established noninvasive positive pressure ventilation (NPPV), were assessed by serum biomarkers, right heart catheterization, blood gases analysis, lung function, Epworth-Sleepiness Scale (ESS), Pittsburgh Sleep Quality Index (PSQI), World Health Organization-functional class (WHO-FC) and health-related quality of life (HRQL) via the Severe Respiratory Insufficiency (SRI) questionnaire. After a planned follow-up of 5 years patients were reassessed regarding vital status, WHO-FC, ESS, SRI, PSQI, body mass index (BMI) and NPPV use. Prognostic markers were explored using univariate and multivariate Cox regression analyses.

RESULTS

At the 5-year follow-up, BMI tended to decrease (P = 0.05), while WHO-FC, ESS and PSQI remained unchanged. HRQL deteriorated in terms of SRI summary score and most subdomains (P < .05 each). NPPV adherence still was high (89%), while daily NPPV use increased from 6.7 (5.1; 8.0) h/d to 8.2 (7.4; 9.0) h/d (P < .05). After a 5-year follow-up, mortality was 25.8%. In univariate regression analyses only age > 69.5 years (HR = 4.145, 95%-CI = 1.180-14.565, P = 0.016), NT-proBNP > 1256 pg/mL (HR = 5.162, 95%-CI = 1.136-23.467, P = 0.018), diffusion capacity for carbon monoxide (DLCO, %pred) (HR = 0.341, 95%-CI = 0.114-1.019, P = 0.043) and higher oxygen use during daytime (HR = 5.236, 95%-CI = 1.489-18.406, P = 0.004) predicted mortality. No independent factor predicting mortality was detected in multivariate analysis.

CONCLUSION

Despite a high long-term NPPV use HRQL worsened. Age, oxygen use at baseline, DLCO (%pred) and NT-proBNP, as a surrogate parameter for PH, were related to long-term survival.

Obesity, Systemic Hypertension, and Pulmonary Hypertension: A Tale of Three Diseases

Cardiovascular disease (CVD), especially ischemic heart disease and stroke, is the major cause of death worldwide, accounting for more than one-third of all deaths annually. Hypertension is the most prevalent and modifiable risk factor of CVD-related deaths. The same is true for obesity, which is currently being recognized as a major global epidemic. The prevalence of obesity in the United States has increased dramatically, from 13.4% in 1960 to 36.5% in 2014, with as much as 70.7% of the American adult population being overweight or obese (CDC). Epidemiological studies have shown that obesity predisposes to hypertension and CVD - with the relationship between markers of obesity and blood pressure being almost linear across different populations. In this review, we discuss systemic and pulmonary hypertension in the context of obesity.

Effect of Obesity on Pulmonary Vascular Hemodynamics

CONTEXT

Obesity-related pulmonary arterial hypertension (PAH) is associated with hypoxia and metabolic abnormalities. Although right heart catheterization is the gold standard method for the diagnosis of PAH, Doppler echocardiography is more common. On the other hand, there is no definite echocardiographic parameter for PAH diagnosis. Novel echocardiographic parameter, pulmonary pulse transit time (pPTT), is assumed to be a surrogate marker for the assessment of PAH.

AIMS

The aim was to evaluate whether pPTT might be valuable for evaluating pulmonary vascular hemodynamics in obese patients.

SETTINGS AND DESIGN

A cross-sectional observational study.

METHODS

A total of 130 consecutive obese patients and 50 controls were included. Obese patients were divided into three groups according to body mass index (BMI): 25 < BMI <30 kg/m2 formed Group 1, 30 < BMI <35 kg/m2 formed Group 2, and 35

STATISTICAL ANALYSIS USED

Intergroup differences were analyzed with analysis of variance or Kruskal-Wallis test. Pearson's or Spearman's correlation analysis was used for correlation, multivariate logistic regression analysis, and regression.

RESULTS

Statistically significant reduction in pPTT was detected as early as in the first group (361.24 ± 25.54 vs. 391.26 ± 15.07; P = 0.015) and continued throughout Groups 2 and 3 (299.92 ± 35.10 vs. 391.26 ± 15.07; P < 0.0001, and 245.46 ± 11.25 vs. 391.26 ± 15.07; P < 0.0001, respectively). There was a strong negative correlation between pPTT and BMI (r = -0.848, P = 0.001). On linear regression analysis, BMI was found to be an independent risk factor for pPTT (confidence interval: -9.164-6.379, β = -0.525, P = 0.0001).

CONCLUSION

The results of this study suggest that obesity leads to an increase in PAH, and pPTT allows noninvasive determination of the pulmonary hemodynamics in obese patients. pPTT might be a useful parameter in terms of predicting pulmonary hemodynamics and vascular alterations in obese patients. Further studies are warranted to evaluate the association between obesity and PAH.

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Key Words

• Obesity
• pulmonary pulse transit time
• pulmonary vascular hemodynamics

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Affiliation(s)

Mustafa Duran Department of Cardiology, Konya Education and Research Hospital, Konya, Turkey
Murat Ziyrek Department of Cardiology, Konya Education and Research Hospital, Konya, Turkey

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Intermittent Hypoxia Augments Pulmonary Vasoconstrictor Reactivity through PKCβ/Mitochondrial Oxidant Signaling

Pulmonary vasoconstriction resulting from intermittent hypoxia (IH) contributes to pulmonary hypertension (pHTN) in patients with sleep apnea (SA), although the mechanisms involved remain poorly understood. Based on prior studies in patients with SA and animal models of SA, the objective of this study was to evaluate the role of PKCβ and mitochondrial reactive oxygen species (mitoROS) in mediating enhanced pulmonary vasoconstrictor reactivity after IH. We hypothesized that PKCβ mediates vasoconstriction through interaction with the scaffolding protein PICK1 (protein interacting with C kinase 1), activation of mitochondrial ATP-sensitive potassium channels (mitoK_ATP), and stimulated production of mitoROS. We further hypothesized that this signaling axis mediates enhanced vasoconstriction and pHTN after IH. Rats were exposed to IH or sham conditions (7 h/d, 4 wk). Chronic oral administration of the antioxidant Tempol or the PKCβ inhibitor LY-333531 abolished IH-induced increases in right ventricular systolic pressure and right ventricular hypertrophy. Furthermore, scavengers of O₂^- or mitoROS prevented enhanced PKCβ-dependent vasoconstrictor reactivity to endothelin-1 in pulmonary arteries from IH rats. In addition, this PKCβ/mitoROS signaling pathway could be stimulated by the PKC activator PMA in pulmonary arteries from control rats, and in both rat and human pulmonary arterial smooth muscle cells. These responses to PMA were attenuated by inhibition of mitoK_ATP or PICK1. Subcellular fractionation and proximity ligation assays further demonstrated that PKCβ acutely translocates to mitochondria upon stimulation and associates with PICK1. We conclude that a PKCβ/mitoROS signaling axis contributes to enhanced vasoconstriction and pHTN after IH. Furthermore, PKCβ mediates pulmonary vasoconstriction through interaction with PICK1, activation of mitoK_ATP, and subsequent mitoROS generation.

Involvement of Low-Density Lipoprotein Receptor in the Pathogenesis of Pulmonary Hypertension

Background

Recently, we and others have reported a causal role for oxidized lipids in the pathogenesis of pulmonary hypertension (PH). However, the role of low‐density lipoprotein receptor (LDL‐R) in PH is not known.

Methods and Results

We examined the role of LDL‐R in the development of PH and determined the efficacy of high‐density lipoprotein mimetic peptide 4F in mitigating PH. Explanted human lungs and plasma from patients with PH and control subjects were analyzed for gene expression, histological characteristics, and lipoprotein oxidation. Male LDL‐R null (LDL‐R knockout) mice (12–15 months old) were fed chow, Western diet (WD), WD with 4F, and WD with scramble peptide for 12 weeks. Serial echocardiography, cardiac catheterization, oxidized LDL assay, real‐time quantitative reverse transcription–polymerase chain reaction, and histological analysis were performed. The effect of LDL‐R knockdown and oxidized LDL on human pulmonary artery smooth muscle cell proliferation was assessed in vitro. LDL‐R and CD36 expression levels were significantly downregulated in the lungs of patients with PH. Patients with PH also had increased lung lipid deposits, oxidized LDL, E06 immunoreactivity, and plasma oxidized LDL/LDL ratio. LDL‐R knockout mice on WD developed PH, right ventricular hypertrophy, right ventricular dysfunction, pulmonary vascular remodeling, fibrosis, and lipid deposition in lungs, aortic atherosclerosis, and left ventricular dysfunction, which were prevented by 4F. Interestingly, PH in WD group preceded left ventricular dysfunction. Oxidized LDL or LDL‐R knockdown significantly increased proliferation of human pulmonary artery smooth muscle cells in vitro.

Conclusions

Human PH is associated with decreased LDL‐R in lungs and increased oxidized LDL in lungs and plasma. WD‐fed LDL‐R knockout mice develop PH and right ventricular dysfunction, implicating a role for LDL‐R and oxidized lipids in PH.

Nocturnal Hypoxemia Impacts Right Ventricle Diastolic Function in Obstructive Sleep Apnea: A Retrospective Observational Study

Obstructive sleep apnea (OSA), although a growing healthcare problem and documented risk factor for cardiovascular diseases, is still under-diagnosed in cardiac patients. To investigate the correlation between OSA and echocardiographic parameters of right ventricle diastolic (RVD) dysfunction, in particular trans-tricuspid E-wave deceleration time (EDT), we retrospectively analyzed data of 103 pure (comorbidity-free) OSA patients with comprehensive echocardiographic examination (ETT). Apnea/hypopnea index (AHI), oxygen desaturation index (ODI), mean nighttime oxyhemoglobin saturation (SpO2), time elapsed with SpO2 < 90% (T90) and mean peak desaturation of nocturnal events (Mdes, graded as mild, medium or severe) were compared with echocardiographic parameters. We found RVD dysfunction present in 58.3% of patients. Altered EDT correlated significantly with mean SpO2, T90, and Mdes (p < 0.01, all). Nocturnal desaturators had a significantly worse EDT than non-desaturators (p = 0.027) and a higher risk of prolonged EDT (odds ratio, OR = 2.86). EDT differed significantly according to Mdes severity (p = 0.005) with a higher risk of prolonged EDT in medium/severe vs. mild Mdes (OR = 3.44). EDT detected the presence of RVD dysfunction in 58.3% of our pure OSA patients. It correlated poorly with AHI severity but strongly with nocturnal desaturation severity, independently of age. This ETT marker may be useful for deciding appropriate diagnostic and therapeutic strategies.

The burden of comorbidities in pulmonary arterial hypertension

Patients with comorbidities are often excluded from clinical trials, limiting the evidence base for pulmonary arterial hypertension (PAH)-specific therapies. This review aims to discuss the effect of comorbidities on the diagnosis and management of PAH. The comorbidities discussed in this review (systemic hypertension, obesity, sleep apnoea, clinical depression, obstructive airway disease, thyroid disease, diabetes, and ischaemic cardiovascular event) were chosen based on their prevalence in patients with idiopathic PAH in the REVEAL registry (Registry to EValuate Early and Long-term PAH disease management). Comorbidities can mask the symptoms of PAH, leading to delays in diagnosis and also difficulty evaluating disease progression and treatment effects. Due to the multifactorial pathophysiology of pulmonary hypertension (PH), the presence of comorbidities can lead to difficulties in distinguishing between Group 1 PH (PAH) and the other group classifications of PH. Many comorbidities contribute to the progression of PAH through increased pulmonary artery pressures and cardiac output, therefore treatment of the comorbidity may also reduce the severity of PAH. Similarly, the development of one comorbidity can be a risk factor for the development of other comorbidities. The management of comorbidities requires consideration of drug interactions, polypharmacy, adherence and evidence-based strategies. A multidisciplinary team should be involved in the management of patients with PAH and comorbidities, with appropriate referral to supportive services when necessary. The treatment goals and expectations of patients must be managed in the context of comorbidities.

A Case of Right Ventricular Dysfunction with Right Ventricular Failure Secondary to Obesity Hypoventilation Syndrome

Patient: Male, 53

Final Diagnosis: Right ventricular dysfunction secondary to obesity hypoventilation syndrome

Symptoms: Shortness of breath

Medication: —

Clinical Procedure: Echocardiogram (TTE)

Specialty: Cardiology

Natriuretic peptide receptor C contributes to disproportionate right ventricular hypertrophy in a rodent model of obesity-induced heart failure with preserved ejection fraction with pulmonary hypertension

Heart failure with preserved ejection fraction (HFpEF) currently has no therapies that improve mortality. Right ventricular dysfunction and pulmonary hypertension are common in HFpEF, and thought to be driven by obesity and metabolic syndrome. Thus, we hypothesized that an animal model of obesity-induced HFpEF with pulmonary hypertension would provide insight into the pathogenesis of right ventricular failure in HFpEF. Two strains of mice, one susceptible (AKR) and one resistant (C3H) to obesity-induced HFpEF, were fed high fat (60% fat) or control diet for 0, 2, or 20 weeks and evaluated by cardiac catheterization and echocardiography for development of right ventricular dysfunction, pulmonary hypertension, and HFpEF. AKR, but not C3H, mice developed right ventricular dysfunction, pulmonary hypertension, and HFpEF. NPRC, which antagonizes beneficial natriuretic peptide signaling, was found in RNA sequencing to be the most differentially upregulated gene in the right ventricle, but not left ventricle or lung, of AKR mice that developed pulmonary hypertension and HFpEF. Overexpression of NPRC in H9C2 cells increased basal cell size and increased expression of hypertrophic genes, MYH7 and NPPA. In conclusion, we have shown that NPRC contributes to right ventricular modeling in obesity-induced pulmonary hypertension-HFpEF by increasing cardiomyocyte hypertrophy. NPRC may represent a promising therapeutic target for right ventricular dysfunction in pulmonary hypertension-HFpEF.

Increased pulmonary artery diameter is associated with reduced FEV1 in former World Trade Center workers

RATIONALE

Occupational exposures at the WTC site after September 11, 2001 have been associated with several presumably inflammatory lower airway diseases. Pulmonary arterial enlargement, as suggested by an increased ratio of the diameter of the pulmonary artery to the diameter of the aorta (PAAr) has been reported as a computed tomographic (CT) scan marker of adverse respiratory health outcomes, including WTC-related disease. In this study, we sought to utilize a novel quantitative CT (QCT) measurement of PAAr to test the hypothesis that an increased ratio is associated with FEV1 below each subject's statistically determined lower limit of normal (FEV1  < LLN).

METHODS

In a group of 1,180 WTC workers and volunteers, we examined whether FEV1  < LLN was associated with an increased QCT-measured PAAr, adjusting for previously identified important covariates.

RESULTS

Unadjusted analyses showed a statistically significant association of FEV1  < LLN with PAAr (35.3% vs 24.7%, P = 0.0001), as well as with height, body mass index, early arrival at the WTC disaster site, shorter WTC exposure duration, post-traumatic stress disorder checklist (PCL) score, wall area percent and evidence of bronchodilator response. The multivariate logistic regression model confirmed the association of FEV1  < LLN with PAAr (OR 1.63, 95% CI 1.21, 2.20, P = 0.0015) and all the unadjusted associations, except for PCL score.

CONCLUSIONS

In WTC workers, FEV1  < LLN is associated with elevated PAAr which, although likely multifactorial, may be related to distal vasculopathy, as has been hypothesized for chronic obstructive pulmonary disease.

Obesity paradox in cardiovascular disease: where do we stand?

Obesity is associated with an increased risk of developing cardiovascular disease (CVD), particularly heart failure (HF) and coronary heart disease (CHD). The mechanisms through which obesity increases CVD risk involve changes in body composition that can affect hemodynamics and alters heart structure. Pro-inflammatory cytokines produced by the adipose tissue itself which can induce cardiac dysfunction and can promote the formation of atherosclerotic plaques. When obesity and HF or CHD coexist, individuals with class I obesity present a more favorable prognosis compared to individuals who are normal or underweight. This phenomenon has been termed the "obesity paradox." Obesity is defined as an excess fat mass (FM), but individuals with obesity typically also present with an increased amount of lean mass (LM). The increase in LM may explain part of the obesity paradox as it is associated with improved cardiorespiratory fitness (CRF), a major determinant of clinical outcomes in the general population, but particularly in those with CVD, including HF. While increased LM is a stronger prognosticator in HF compared to FM, in patients with CHD excess FM can exert protective effects particularly when not associated with increased systemic inflammation. In the present review, we discuss the mechanisms through which obesity may increase the risk for CVD, and how it may exert protective effects in the setting of established CVD, with a focus on body composition. We also highlight the importance of measuring or estimating CRF, including body composition-adjusted measures of CRF (ie, lean peak oxygen consumption) for an improved risk status stratification in patients with CVD and finally, we discuss the potential non-pharmacologic therapeutics, such as exercise training and dietary interventions, aimed at improving CRF and perhaps clinical outcomes.

Pulmonary arterial remodelling by deficiency of peroxisome proliferator-activated receptor-γ in murine vascular smooth muscle cells occurs independently of obesity-related pulmonary hypertension

Background

Obesity is associated with cardiovascular complications, including pulmonary hypertension (PH). Reports suggest that peroxisome proliferator-activated receptor-γ (PPARγ) has direct action in preventing vascular remodelling in PH. Here we dissected the specific role of high-fat-diet (HFD)-induced obesity and vascular smooth muscle cell (VSMC)-PPARγ for remodelling of small pulmonary arteries.

Methods

Wild-type (WT) and VSMC-specific PPARγ-knockout (SmPparγ^−/−) mice were fed a low-fat-diet (LFD, 10% kcal from fat) or HFD (60% kcal from fat) for 24 weeks. Mice were metabolically phenotyped (e.g. weight development, insulin/glucose tolerance) at the beginning, and after 12 and 24 weeks, respectively. At 24 weeks additionally pulmonary pressure, heart structure, pulmonary vascular muscularization together with gene and protein expression in heart and lung tissues were determined.

Results

HFD increased right ventricular systolic pressure (RVSP) to a similar extent in WT and SmPparγ^−/− mice. HFD decreased glucose tolerance and insulin sensitivity in both WT and SmPparγ^−/− mice. Importantly, the increase in RVSP correlated with the degree of insulin resistance. However, VSMC-PPARγ deficiency increased pulmonary vascular muscularization independently of the diet-induced rise in RVSP. This increase was associated with elevated expression of early growth response protein 1 in heart and osteopontin in lung tissue.

Conclusions

Here we demonstrate a correlation of insulin resistance and pulmonary pressure. Further, deficiency of PPARγ in VSMCs diet-independently leads to increased pulmonary vascular muscularization.