scholarly journals Pulmonary Hypertension in Acute and Chronic High Altitude Maladaptation Disorders

2021 ◽  
Vol 18 (4) ◽  
pp. 1692
Author(s):  
Akylbek Sydykov ◽  
Argen Mamazhakypov ◽  
Abdirashit Maripov ◽  
Djuro Kosanovic ◽  
Norbert Weissmann ◽  
...  
Keyword(s):  
Pulmonary Hypertension ◽  
High Altitude ◽  
Clinical Experience ◽  
Current Knowledge ◽  
Hypoxic Pulmonary Vasoconstriction ◽  
Treatment Options ◽  
Right Heart Failure ◽  
Channel Blockers ◽  
The Right ◽  
Extensive Clinical Experience

Alveolar hypoxia is the most prominent feature of high altitude environment with well-known consequences for the cardio-pulmonary system, including development of pulmonary hypertension. Pulmonary hypertension due to an exaggerated hypoxic pulmonary vasoconstriction contributes to high altitude pulmonary edema (HAPE), a life-threatening disorder, occurring at high altitudes in non-acclimatized healthy individuals. Despite a strong physiologic rationale for using vasodilators for prevention and treatment of HAPE, no systematic studies of their efficacy have been conducted to date. Calcium-channel blockers are currently recommended for drug prophylaxis in high-risk individuals with a clear history of recurrent HAPE based on the extensive clinical experience with nifedipine in HAPE prevention in susceptible individuals. Chronic exposure to hypoxia induces pulmonary vascular remodeling and development of pulmonary hypertension, which places an increased pressure load on the right ventricle leading to right heart failure. Further, pulmonary hypertension along with excessive erythrocytosis may complicate chronic mountain sickness, another high altitude maladaptation disorder. Importantly, other causes than hypoxia may potentially underlie and/or contribute to pulmonary hypertension at high altitude, such as chronic heart and lung diseases, thrombotic or embolic diseases. Extensive clinical experience with drugs in patients with pulmonary arterial hypertension suggests their potential for treatment of high altitude pulmonary hypertension. Small studies have demonstrated their efficacy in reducing pulmonary artery pressure in high altitude residents. However, no drugs have been approved to date for the therapy of chronic high altitude pulmonary hypertension. This work provides a literature review on the role of pulmonary hypertension in the pathogenesis of acute and chronic high altitude maladaptation disorders and summarizes current knowledge regarding potential treatment options.

scholarly journals Thin Air Resulting in High Pressure: Mountain Sickness and Hypoxia-Induced Pulmonary Hypertension

2017 ◽  
Vol 2017 ◽  
pp. 1-17 ◽  
Author(s):  
Jan Grimminger ◽  
Manuel Richter ◽  
Khodr Tello ◽  
Natascha Sommer ◽  
Henning Gall ◽  
...  
Keyword(s):  
Pulmonary Hypertension ◽  
High Altitude ◽  
Hypobaric Hypoxia ◽  
Current Knowledge ◽  
Treatment Options ◽  
Acute Response ◽  
Mechanisms Of Adaptation ◽  
Mountain Sickness

With rising altitude the partial pressure of oxygen falls. This phenomenon leads to hypobaric hypoxia at high altitude. Since more than 140 million people permanently live at heights above 2500 m and more than 35 million travel to these heights each year, understanding the mechanisms resulting in acute or chronic maladaptation of the human body to these circumstances is crucial. This review summarizes current knowledge of the body’s acute response to these circumstances, possible complications and their treatment, and health care issues resulting from long-term exposure to high altitude. It furthermore describes the characteristic mechanisms of adaptation to life in hypobaric hypoxia expressed by the three major ethnic groups permanently dwelling at high altitude. We additionally summarize current knowledge regarding possible treatment options for hypoxia-induced pulmonary hypertension by reviewing in vitro, rodent, and human studies in this area of research.

scholarly journals MAP kinase kinase kinase-2 (MEKK2) regulates hypertrophic remodeling of the right ventricle in hypoxia-induced pulmonary hypertension

2013 ◽  
Vol 304 (2) ◽  
pp. H269-H281 ◽  
Author(s):  
R. Dale Brown ◽  
S. Kelly Ambler ◽  
Min Li ◽  
Timothy M. Sullivan ◽  
Lauren N. Henry ◽  
...  
Keyword(s):  
Gene Expression ◽  
Pulmonary Hypertension ◽  
Right Ventricle ◽  
Cardiac Myocyte ◽  
Chronic Hypoxia ◽  
Regulatory Protein ◽  
Right Heart Failure ◽  
Inflammatory Gene Expression ◽  
Inflammatory Gene ◽  
The Right

Pulmonary hypertension (PH) results in pressure overload of the right ventricle (RV) of the heart, initiating pathological RV remodeling and ultimately leading to right heart failure. Substantial research indicates that signaling through the MAPK superfamily mediates pathological cardiac remodeling. These considerations led us to test the hypothesis that the regulatory protein MAPKKK-2 (MEKK2) contributes to RV hypertrophy in hypoxia-induced PH. Transgenic mice with global knockout of MEKK2 (MEKK2−/− mice) and age-matched wild-type (WT) mice were exposed to chronic hypobaric hypoxia (10% O2, 6 wk) and compared with animals under normoxia. Exposure to chronic hypoxia induced PH in WT and MEKK2−/− mice. In response to PH, WT mice showed RV hypertrophy, demonstrated as increased ratio of RV weight to body weight, increased RV wall thickness at diastole, and increased cardiac myocyte size compared with normoxic control animals. In contrast, each of these measures of RV hypertrophy seen in WT mice after chronic hypoxia was attenuated in MEKK2−/− mice. Furthermore, chronic hypoxia elicited altered programs of hypertrophic and inflammatory gene expression consistent with pathological RV remodeling in WT mice; MEKK2 deletion selectively inhibited inflammatory gene expression compared with WT mice. The actions of MEKK2 were mediated in part through regulation of the abundance and phosphorylation of its effector, ERK5. In conclusion, signaling by MEKK2 contributes to RV hypertrophy and altered myocardial inflammatory gene expression in response to hypoxia-induced PH. Therapies targeting MEKK2 may protect the myocardium from hypertrophy and pathological remodeling in human PH.

Alteration of the pulsatile load in the high-altitude calf model of pulmonary hypertension

1991 ◽  
Vol 70 (2) ◽  
pp. 859-868 ◽  
Author(s):  
B. D. Zuckerman ◽  
E. C. Orton ◽  
K. R. Stenmark ◽  
J. A. Trapp ◽  
J. R. Murphy ◽  
...  
Keyword(s):  
Pulmonary Hypertension ◽  
Right Ventricular ◽  
High Altitude ◽  
Arterial Wall ◽  
Arterial Compliance ◽  
Arterial Elasticity ◽  
Arterial Distensibility ◽  
Pulmonary Arterial ◽  
Pulsatile Load ◽  
The Right

We compared main pulmonary arterial elasticity and global pulmonary arterial compliance in control and high-altitude (HA) calves to determine whether 1) changes in pulmonary arterial elasticity are contributing to an increase in the oscillatory load of the right ventricle in this model of pulmonary hypertension and 2) measured changes in stiffness of the HA calves' arterial wall are the result of both an increase in pressure and an alteration of the material properties of the HA calves' arterial wall. Newborn calves were placed at 4,300 m simulated altitude for 14 days, and control calves were kept at 1,500 m. The HA calves were then reacclimatized to 1,500 m for 24 h so that baseline pressures of the two groups were similar. Open-chest main pulmonary arterial and right ventricular micromanometric pressures, ultrasonic main pulmonary arterial diameter, and green dye flow were measured under baseline conditions and then under moderate and severely hypoxic conditions to make measurements at both baseline and increased pulmonary pressures. At elevated pressures, the pressure-diameter relationship was noted to be nonlinear, and a characteristic late systolic peaking of the right ventricular pressure waveform was seen. The Peterson pressure-strain modulus, pulse wave velocity, characteristic impedance, and global compliance (3 element windkessel) were calculated. The calculated variables were all shown to be pressure dependent, and no intrinsic differences in stiffness were seen between the control and HA animals when mean pressure was taken into account. Pulmonary arterial histology demonstrated, however, a characteristic increase in wall thickness in the HA animals. Thus, in this model of pulmonary hypertension, major changes in elasticity and pulsatile load are primarily due to an increase in pulmonary pressure. The structural changes present in the HA calves' arterial wall did not separately produce any measurable changes in arterial distensibility or the oscillatory load.

scholarly journals Chronic Thromboembolic Pulmonary Hypertension – What Have We Learned From Large Animal Models

2021 ◽  
Vol 8 ◽  
Author(s):  
Kelly Stam ◽  
Sebastian Clauss ◽  
Yannick J. H. J. Taverne ◽  
Daphne Merkus
Keyword(s):  
Pulmonary Hypertension ◽  
Animal Models ◽  
Current Knowledge ◽  
Pulmonary Arteries ◽  
Chronic Thromboembolic Pulmonary Hypertension ◽  
Large Animal ◽  
Large Animal Models ◽  
Microvascular Remodeling ◽  
Thromboembolic Pulmonary Hypertension ◽  
The Right

Chronic thrombo-embolic pulmonary hypertension (CTEPH) develops in a subset of patients after acute pulmonary embolism. In CTEPH, pulmonary vascular resistance, which is initially elevated due to the obstructions in the larger pulmonary arteries, is further increased by pulmonary microvascular remodeling. The increased afterload of the right ventricle (RV) leads to RV dilation and hypertrophy. This RV remodeling predisposes to arrhythmogenesis and RV failure. Yet, mechanisms involved in pulmonary microvascular remodeling, processes underlying the RV structural and functional adaptability in CTEPH as well as determinants of the susceptibility to arrhythmias such as atrial fibrillation in the context of CTEPH remain incompletely understood. Several large animal models with critical clinical features of human CTEPH and subsequent RV remodeling have relatively recently been developed in swine, sheep, and dogs. In this review we will discuss the current knowledge on the processes underlying development and progression of CTEPH, and on how animal models can help enlarge understanding of these processes.

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

2019 ◽  
Vol 53 (1) ◽  
pp. 1801900 ◽  
Author(s):  
Anton Vonk Noordegraaf ◽  
Kelly Marie Chin ◽  
François Haddad ◽  
Paul M. Hassoun ◽  
Anna R. Hemnes ◽  
...  
Keyword(s):  
Pulmonary Hypertension ◽  
Right Ventricle ◽  
Vascular System ◽  
Right Heart Failure ◽  
Imaging Data ◽  
Right Heart ◽  
Future Directions ◽  
Right Heart Catheterisation ◽  
The Right ◽  
Key Pathways

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.

Pathophysiological Considerations concerning Uni- and Biventricular Mechanical Cardiac Assist

1997 ◽  
Vol 20 (12) ◽  
pp. 684-691 ◽  
Author(s):  
F.R. Waldenberger
Keyword(s):  
Pulmonary Hypertension ◽  
Right Heart Failure ◽  
Assisted Circulation ◽  
Left Heart ◽  
Right Heart ◽  
Early Reperfusion ◽  
Cardiac Assist ◽  
Mechanical Unloading ◽  
The Right ◽  
The Impact

Mechanical assisted circulation by the means of cardiac assist devices is a routine procedure in modern cardiac surgery and cardiology. We investigated the impact of mechanical unloading on regional myocardial “stunning” and the influence of assisted circulation on left heart and right heart failure persevered by an ultimate addition of pulmonary hypertension in experimental set ups. We found that mechanical unloading either during ischemia or in the early reperfusion phase attenuates stunning and enhances the return of synchronous heart performance. In our global dysfunction model we showed that the right heart is dispensable. Sufficient inflow to the left heart is provided unless pulmonary hypertension is present. Also additional left heart support can not overcome the deleterious situation and in select cases only additional right heart support can prevent the “low LVAD output” syndrome. We conclude that mechanical assisted circulation and mechanical unloading are beneficial in case of regional and global dysfunction persevered by pulmonary hypertension, however, the knowledge about interactions of assist systems and the circulation has to be improved in order to optimize clinical assist device performance.

P5370Pulmonary pressure overload stimulates cardiac stem or progenitor cell-derived cardiac regeneration in the right ventricular area

2019 ◽  
Vol 40 (Supplement_1) ◽  
Author(s):  
M Kanda ◽  
T Nagai ◽  
N Kondou ◽  
K Tateno ◽  
M Hirose ◽  
...  
Keyword(s):  
Heart Failure ◽  
Pulmonary Hypertension ◽  
Right Ventricular ◽  
Progenitor Cell ◽  
Pressure Overload ◽  
Right Heart Failure ◽  
Left Ventricular ◽  
Free Wall ◽  
Right Heart ◽  
The Right

Abstract Introduction and purpose The number of patients with right heart failure due to pulmonary hypertension has been increasing. Although several drugs have reportedly improved pulmonary hypertension, no treatments have been established for decompensated right heart failure. The heart has an innate ability to regenerate, and cardiac stem or progenitor cells (e.g., side population [SP] cells) have been reported to contribute to the regeneration process. However, their contribution to right ventricular pressure overload has not been clarified. Here, this regeneration process was evaluated using a genetic fate-mapping model. Methods and results We used Cre-LacZ mice, in which more than 99.9% of the cardiomyocytes in the left ventricular field were positive for 5-bromo-4-chloro-3-indolyl-β-D-galactoside (X-gal) staining immediately after tamoxifen injection. Then, we performed either a pulmonary binding (PAB) or sham operation on the main pulmonary tract. In the PAB-treated mice, the right ventricular cavity was significantly enlarged (right-to-left ventricular [RV/LV] ratio, 0.24±0.04 in the sham group and 0.68±0.04 in the PAB group). Increased peak flow velocity in the PAB group (1021±80 vs 1351±62 mm/sec) was confirmed by echocardiography. One month after the PAB, the PAB-treated mice had more X-gal-negative (newly generated) cells than the sham mice (94.8±34.2 cells/mm2 vs 23.1±10.5 cells/mm2; p<0.01). The regeneration was biased in the RV free wall (RV free wall, 225.5±198.7 cells/mm2; septal area, 88.9±56.5/mm2; LV lateral area, 46.8±22.0/mm2; p<0.05). To examine the direct effects of PAB on the cardiac progenitor cells, bromodeoxyuridine was administered to the mice daily until 1 week after the PAB operation. Then, the hearts were isolated and SP cells were harvested. The SP cell population increased from 0.65±0.23% in the sham mice to 1.87% ± 1.18% in the PAB-treated mice. Immunostaining analysis revealed a significant increase in the number of BrdU-positive SP cells, from 11.6±2.0% to 44.0±18%, therefore showing SP cell proliferation. Conclusions Pulmonary pressure overload stimulated cardiac stem or progenitor cell-derived regeneration with a RV bias, and SP cell proliferation may partially contribute to this process. Acknowledgement/Funding JSPS KAKENHI Grant Number JP 17K17636, GSK Japan Research Grant 2016

scholarly journals Chronic thromboembolic pulmonary hypertension – still evolving

2020 ◽  
Vol 2020 (1) ◽  
Author(s):  
Mario Gerges ◽  
Magdi Yacoub
Keyword(s):  
Pulmonary Hypertension ◽  
Medical Therapy ◽  
Treatment Options ◽  
Pulmonary Arteries ◽  
Chronic Thromboembolic Pulmonary Hypertension ◽  
Right Heart Failure ◽  
Pulmonary Vasculature ◽  
Pulmonary Hemodynamics ◽  
Thromboembolic Pulmonary Hypertension ◽  
Multiple Treatments

Chronic thromboembolic pulmonary hypertension (CTEPH) is one of the leading causes of severe pulmonary hypertension (PH). The disease is still underdiagnosed, and the true prevalence is unknown. CTEPH is characterized by intraluminal non-resolving thrombus organization and fibrous stenosis, or complete obliteration of pulmonary arteries, promoted by progressive remodeling of the pulmonary vasculature. One consequence of this is an increase in pulmonary vascular resistance and pressure, resulting in PH and progressive right heart failure, leading to death if left untreated.Endovascular disobliteration by pulmonary endarterectomy (PEA) is the preferred treatment for CTEPH patients. PEA surgery is the only technique that can potentially cure CTEPH disease, especially in patients with fresh or organized thrombi of the proximal branches of pulmonary arteries. However, not all patients are eligible for PEA surgery. Recent research has provided evidence suggesting balloon pulmonary angioplasty (BPA) and targeted medical therapy as additional promising available treatments options for inoperable CTEPH and recurrent/persistent PH after PEA surgery.Studies on BPA have shown it to improve pulmonary hemodynamics, symptoms, exercise capacity and RV function in inoperable CTEPH. Subsequently, BPA has developed into an essential component of the modern era of CTEPH treatment. Large randomized controlled trials have demonstrated varying significant improvements with targeted medical therapy in technically inoperable CTEPH patients. Thus, treatment of CTEPH requires a comprehensive multidisciplinary assessment, including an experienced PEA surgeon, PH specialist, BPA interventionist and CTEPH-trained radiologist at expert centers. In this comprehensive review, we address the latest developments in the fast-evolving field of CTEPH. These include advancements in imaging modalities and developments in operative and interventional techniques, which have widened the range of patients who may benefit from these procedures. The efficacy and safety of targeted medical therapies in CTEPH patients are also discussed. As the treatment options for CTEPH improve, hybrid management involving multiple treatments in the same patient may become a viable option in the near future.

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