-
European Journal of Radiology Jan 2017As pulmonary functional imaging moves beyond the realm of the radiologist and physicist, it is important that imagers have a common language and understanding of the... (Review)
Review
As pulmonary functional imaging moves beyond the realm of the radiologist and physicist, it is important that imagers have a common language and understanding of the relevant physiology of the lung. This review will focus on key physiological concepts and pitfalls relevant to functional lung imaging.
Topics: Humans; Lung; Pulmonary Circulation; Pulmonary Disease, Chronic Obstructive; Pulmonary Gas Exchange; Regional Blood Flow; Ventilation-Perfusion Ratio
PubMed: 27707586
DOI: 10.1016/j.ejrad.2016.09.027 -
Current Opinion in Cardiology Nov 2015Pulmonary hypertension is a progressive disease of the pulmonary vasculature characterized by increased vascular resistance and pressure overload of the right ventricle.... (Review)
Review
PURPOSE OF REVIEW
Pulmonary hypertension is a progressive disease of the pulmonary vasculature characterized by increased vascular resistance and pressure overload of the right ventricle. This review aims to describe the diagnostic and prognostic role of echocardiography in pulmonary hypertension with particular consideration of relative strengths, weaknesses and new advances.
RECENT FINDINGS
Although right heart catheterization (RHC) remains the gold standard, echocardiography represents an accessible and feasible real-world tool for screening, differential diagnostic, follow-up assessments and risk stratification in pulmonary hypertension. In the context of clinical scenario and multimaging approach, echocardiography provides accurate measurements of pulmonary haemodynamics, either at rest and/or during exercise, and is particularly useful in ruling out secondary causes of pulmonary hypertension and/or detecting preclinical stages. The use of advanced noninvasive imaging techniques may provide additional information in assessing right heart structure and function.
SUMMARY
Advances in echocardiography and the multimodality imaging approach continue to provide new understandings and opportunities for the study of the right heart-pulmonary circulation unit in pulmonary hypertension.
Topics: Echocardiography, Doppler; Humans; Hypertension, Pulmonary; Pulmonary Circulation
PubMed: 26447500
DOI: 10.1097/HCO.0000000000000217 -
Seminars in Respiratory and Critical... Oct 2023
Review
Topics: Humans; Hypertension, Pulmonary; Lung; Pulmonary Artery; Pulmonary Circulation
PubMed: 37816343
DOI: 10.1055/s-0043-1771162 -
Annals of the American Thoracic Society Feb 2016The normal pulmonary circulation is a low-pressure, high-compliance system. Pulmonary arterial compliance decreases in the presence of pulmonary hypertension because of... (Review)
Review
The normal pulmonary circulation is a low-pressure, high-compliance system. Pulmonary arterial compliance decreases in the presence of pulmonary hypertension because of increased extracellular matrix/collagen deposition in the pulmonary arteries. Loss of pulmonary arterial compliance has been consistently shown to be a predictor of increased mortality in patients with pulmonary hypertension, even more so than pulmonary vascular resistance in some studies. Decreased pulmonary arterial compliance causes premature reflection of waves from the distal pulmonary vasculature, leading to increased pulsatile right ventricular afterload and eventually right ventricular failure. Evidence suggests that decreased pulmonary arterial compliance is a cause rather than a consequence of distal small vessel proliferative vasculopathy. Pulmonary arterial compliance decreases early in the disease process even when pulmonary artery pressure and pulmonary vascular resistance are normal, potentially enabling early diagnosis of pulmonary vascular disease, especially in high-risk populations. With the recognition of the prognostic importance of pulmonary arterial compliance, its impact on right ventricular function, and its contributory role in the development and progression of distal small-vessel proliferative vasculopathy, pulmonary arterial compliance is an attractive target for the treatment of pulmonary hypertension.
Topics: Compliance; Heart Failure; Humans; Hypertension, Pulmonary; Neovascularization, Pathologic; Prognosis; Pulmonary Artery; Pulmonary Circulation; Vascular Stiffness; Ventricular Dysfunction, Right
PubMed: 26848601
DOI: 10.1513/AnnalsATS.201509-599FR -
European Respiratory Review : An... Mar 2022Pulmonary arterial pressure rises minimally during exercise. The pulmonary microcirculation accommodates increasing blood flow recruitment of pulmonary capillaries and,... (Review)
Review
Pulmonary arterial pressure rises minimally during exercise. The pulmonary microcirculation accommodates increasing blood flow recruitment of pulmonary capillaries and, at higher flows, by distention of already perfused capillaries. The flow transition range between recruitment and distention has not been studied or compared across mammalian species, including humans. We hypothesised that the range would be similar. Functional pulmonary capillary surface area (FCSA) can be estimated using validated metabolic techniques. We reviewed data from previous studies in three mammalian species (perfused rabbit lungs and dog lung lobes, and exercising humans) and generated blood flow-FCSA curves over a range of flows. We noted where the curves diverged from the theoretical line of pure recruitment (Recruitment) and determined the flow where the curve slope equalled 50% that of Recruitment, or equalled that of a theoretical curve representing full capillary distention (Distention). The three mammalian species have similar flow ranges for the transition from predominantly recruitment to predominantly distention, with dogs having the highest transition point. Within the physiological range of most daily activity, the species are similar and accommodate increasing blood flow mainly recruitment, with progressive distention at higher flows. This is highly relevant to pulmonary physiology during exercise.
Topics: Animals; Blood Pressure; Capillaries; Dogs; Hemodynamics; Humans; Lung; Pulmonary Circulation; Rabbits
PubMed: 35197268
DOI: 10.1183/16000617.0248-2021 -
European Respiratory Review : An... Sep 2014The loss of pulmonary vessels has been shown to be related to the severity of pulmonary hypertension in patients with chronic obstructive pulmonary disease (COPD). The... (Review)
Review
The loss of pulmonary vessels has been shown to be related to the severity of pulmonary hypertension in patients with chronic obstructive pulmonary disease (COPD). The severity of hypoxaemia is also related to pulmonary hypertension and pulmonary vascular resistance in these patients, suggesting that the hypoxic condition probably plays an important role in this form of pulmonary hypertension. However, pulmonary hypertension also develops in patients with mild COPD without hypoxaemia. Oxygen supplementation therapy often fails to reverse the pulmonary hypertension in these COPD patients, thus suggesting that the pulmonary vascular alterations in those patients may involve different sites of the pulmonary vasculature or a different form of vascular remodelling. It has recently been demonstrated that pulmonary vascular remodelling, resulting in pulmonary hypertension in COPD patients, can develop independently from parenchymal destruction and loss of lung vessels. We wonder whether the changes in the lung microenvironment due to hypoxia and vessel loss have a causative role in the development of pulmonary hypertension in patients with COPD. Herein we review the pathobiological features of the pulmonary vasculature in COPD patients and suggest that pulmonary hypertension can occur with and without emphysematous lung tissue destruction and with and without loss of lung vessels.
Topics: Humans; Hypertension, Pulmonary; Hypoxia; Oxygen; Pulmonary Circulation; Pulmonary Disease, Chronic Obstructive; Vascular Remodeling
PubMed: 25176971
DOI: 10.1183/09059180.00007913 -
Heart Failure Clinics Jul 2018Echocardiography is the first step in imaging the right heart pulmonary circulation unit (RH-PCU), and the only one to allow its complete morphologic, functional, and... (Review)
Review
Echocardiography is the first step in imaging the right heart pulmonary circulation unit (RH-PCU), and the only one to allow its complete morphologic, functional, and hemodynamic analysis in all clinical scenarios. Right ventricular (RV) function is not only the consequence of its intrinsic contractile function (morphology and contractility) but also highly dependent on preload, afterload, and ventricular interdependence. Comprehensive echocardiographic examination of RH-PCU allows insight into intrinsic and extrinsic factors of RV function. Newer echocardiographic techniques allow for 3-dimensional evaluation of RV and detailed measurements of regional function using tissue Doppler or speckle tracking-based strain estimates.
Topics: Echocardiography; Heart Ventricles; Hemodynamics; Humans; Pulmonary Circulation; Ventricular Function, Right
PubMed: 29966634
DOI: 10.1016/j.hfc.2018.03.003 -
Experimental Physiology Apr 2023
Topics: Humans; Oxygen; Vasoconstriction; Iron; Hypoxia; Pulmonary Disease, Chronic Obstructive; Pulmonary Gas Exchange; Pulmonary Circulation
PubMed: 36744659
DOI: 10.1113/EP091078 -
Heart Failure Clinics Jul 2018Systemic hypertension is a risk factor for left heart failure, mostly with preserved ejection fraction. Left heart failure is a cause of pulmonary hypertension and... (Review)
Review
Systemic hypertension is a risk factor for left heart failure, mostly with preserved ejection fraction. Left heart failure is a cause of pulmonary hypertension and eventual right ventricular (RV) failure. There has been report of altered RV function in mild to moderate hypertension with preserved systolic as well as diastolic function of the left ventricle. The pathophysiology of this complication of hypertension is unclear. Preserving the RV and preventing the development of pulmonary vascular disease may be considered among the targets of optimized therapy for systemic hypertension.
Topics: Heart Failure; Heart Ventricles; Humans; Hypertension; Hypertension, Pulmonary; Pulmonary Circulation; Ventricular Dysfunction, Right; Ventricular Function, Right
PubMed: 29966624
DOI: 10.1016/j.hfc.2018.02.002 -
Biomedical Engineering Online 2015Patients with repaired or palliated right heart congenital heart disease (CHD) are often left with residual lesions that progress and can result in significant... (Review)
Review
Patients with repaired or palliated right heart congenital heart disease (CHD) are often left with residual lesions that progress and can result in significant morbidity. However, right ventricular-pulmonary arterial evaluation and the timing of reintvervention is still subjective. Currently, it relies on symptomology, or RV imaging-based metrics from echocardiography or MR derived parameters including right ventricular (RV) ejection fraction (EF), end-systolic pressure (ESP), and end-diastolic volume (EDV). However, the RV is coupled to the pulmonary vasculature, and they are not typically evaluated together. For example, the dysfunctional right ventricular-pulmonary circulation (RV-PC) adversely affects the RV myocardial performance resulting in decreased efficiency. Therefore, comprehensive hemodynamic assessment should incorporate changes in RV-PC and energy efficiency for CHD patients. The ventricular pressure-volume relationship (PVR) and other energy-based endpoints derived from PVR, such as stroke work (SW) and ventricular elastance (Ees), can provide a measure of RV performance. However, a detailed explanation of the relationship between RV performance and pulmonary arterial hemodynamics is lacking. More importantly, PVR is impractical for routine longitudinal evaluation in a clinical setting, because it requires invasive catheterization. As an alternative, analytical methods and computational fluid dynamics (CFD) have been used to compute energy endpoints, such as power loss or energy dissipation, in abnormal physiologies. In this review, we review the causes of RV-PA failure and the limitation of current clinical parameters to quantify RV-PC dysfunction. Then, we describe the advantage of currently available energy-based endpoints and emerging energy endpoints, such as energy loss in the Pas or kinetic energy, obtained from a new non-invasive imaging technique, i.e. 4D phase contrast MRI.
Topics: Energy Metabolism; Humans; Magnetic Resonance Imaging; Pulmonary Circulation; Stroke Volume; Ventricular Dysfunction, Right
PubMed: 25602641
DOI: 10.1186/1475-925X-14-S1-S8