Exercise-Induced Pulmonary Hypertension

Evidence and unresolved questions in pulmonary hypertension: Insights from the 5th French Pulmonary Hypertension Network Meeting

Pulmonary hypertension (PH) continues to present significant challenges to the medical community, both in terms of diagnosis and treatment. The advent of the updated 2022 European Society of Cardiology (ESC) and European Respiratory Society (ERS) guidelines has introduced pivotal changes that reflect the rapidly advancing understanding of this complex disease. These changes include a revised definition of PH, updates to the classification system, and treatment algorithm. While these guidelines offer a critical framework for the management of PH, they have also sparked new discussions and questions. The 5th French Pulmonary Hypertension Network Meeting (Le Kremlin-Bicêtre, France, 2023), addressed these emergent questions and fostering a deeper understanding of the disease's multifaceted nature. These discussions were not limited to theoretical advancements but extended into the practical realms of patient management, highlighting the challenges and opportunities in applying the latest guidelines to clinical practice.

Pulmonary Hypertension in Left Heart Diseases: Pathophysiology, Hemodynamic Assessment and Therapeutic Management

Pulmonary hypertension (PH) associated with left heart diseases (PH-LHD), also termed group 2 PH, represents the most common form of PH. It develops through the passive backward transmission of elevated left heart pressures in the setting of heart failure, either with preserved (HFpEF) or reduced (HFrEF) ejection fraction, which increases the pulsatile afterload of the right ventricle (RV) by reducing pulmonary artery (PA) compliance. In a subset of patients, progressive remodeling of the pulmonary circulation resulted in a pre-capillary phenotype of PH, with elevated pulmonary vascular resistance (PVR) further increasing the RV afterload, eventually leading to RV-PA uncoupling and RV failure. The primary therapeutic objective in PH-LHD is to reduce left-sided pressures through the appropriate use of diuretics and guideline-directed medical therapies for heart failure. When pulmonary vascular remodeling is established, targeted therapies aiming to reduce PVR are theoretically appealing. So far, such targeted therapies have mostly failed to show significant positive effects in patients with PH-LHD, in contrast to their proven efficacy in other forms of pre-capillary PH. Whether such therapies may benefit some specific subgroups of patients (HFrEF, HFpEF) with specific hemodynamic phenotypes (post- or pre-capillary PH) and various degrees of RV dysfunction still needs to be addressed.

Combining cardiopulmonary exercise testing with echocardiography: a multiparametric approach to the cardiovascular and cardiopulmonary systems

Exercise intolerance is a prominent feature of several cardiovascular conditions. However, the physical effort requires the intertwined adaptation of several factors, namely the cardiovascular system, the lungs, and peripheral muscles. Several abnormalities in each domain may be present in a given patient. Cardiopulmonary exercise testing (CPET) has been used to investigate metabolic and ventilatory alterations responsible for exercise intolerance but does not allow for direct evaluation of cardiovascular function. However, this can readily be obtained by concomitant exercise-stress echocardiography (ESE). The combined CPET-ESE approach allows for precise and thorough phenotyping of the pathophysiologic mechanisms underpinning exercise intolerance. Thus, it can be used to refine the diagnostic workup of patients with dyspnoea of unknown origin, as well as improve risk stratification and potentially guide the therapeutic approach in specific conditions, including left and right heart failure or valvular heart disease. However, given its hitherto sporadic use, both the conceptual and technical aspects of CPET-ESE are often poorly known by the clinician. Improving knowledge in this field could significantly aid in anticipating individual disease trajectories and tailoring treatment strategies accordingly. Therefore, we designed this review to revise the pathophysiologic correlates of exercise intolerance, the practical principles of the combined CPET-ESE examination, and its main applications according to current literature.

Pulmonary hypertension due to high cardiac output

Pulmonary hypertension (PH) is usually associated with a normal or decreased cardiac output (CO). Less commonly, PH can occur in the context of a hyperdynamic circulation, characterized by high CO (>8 L/min) and/or cardiac index ≥4 L/min/m² in the setting of a decreased systemic vascular resistance. PH due to high CO can occur due to multiple conditions and in general remains understudied. In this review article we describe the pathophysiology, etiology, diagnosis, hemodynamic characteristics, and management of PH in the setting of high CO. It is important to recognize this distinct entity as PH tends to improve with treatment of the underlying etiology and PH specific therapies may worsen the hemodynamic state.

Characterisation of haemodynamic and metabolic abnormalities in the heart failure spectrum: the role of combined cardiopulmonary and exercise echocardiography stress test

Heart failure (HF) is a complex clinical syndrome characterised by different etiologies and a broad spectrum of cardiac structural and functional abnormalities. Current guidelines suggest a classification based on left ventricular ejection fraction (LVEF), distinguishing HF with reduced (HFrEF) from preserved (HFpEF) LVEF. HF should also be thought of as a continuous range of conditions, from asymptomatic stages to clinically manifest syndrome. The transition from one stage to the next is associated with a worse prognosis. While the rate of HF-related hospitalisation is similar in HFrEF and HFpEF once clinical manifestations occur, accurate knowledge of the steps and risk factors leading to HF progression is still lacking, especially in HFpEF. Precise hemodynamic and metabolic characterisation of patients with or at risk of HF may help identify different disease trajectories and risk factors, with the potential to identify specific treatment targets that might offset the slippery slope towards overt clinical manifestations. Exercise can unravel early metabolic and haemodynamic alterations that might be silent at rest, potentially leading to improved risk stratification and more effective treatment strategies. Cardiopulmonary exercise testing (CPET) offers valuable aid to investigate functional alterations in subjects with or at risk of HF, while echocardiography can assess cardiac structure and function objectively, both at rest and during exercise (exercise stress echocardiography, ESE). The purpose of this narrative review is to summarise the potential advantages of using an integrated CPET-ESE evaluation in the characterisation of both subjects at risk of developing HF and patients with stable HF.

Potential Role of Cardiopulmonary Exercise Testing as an Early Screening Tool for Patients With Suspected Pulmonary Hypertension Including Exercise-Induced Pulmonary Hypertension: Results From a Retrospective Analysis

OBJECTIVE

The primary goal of our retrospective case-control study was to evaluate the ability of cardiopulmonary exercise testing to screen for underlying exercise-induced pulmonary hypertension (EIPH) in symptomatic patients who had a negative stress test and elevated right ventricular systolic pressure on echocardiogram. We also evaluated long-acting nitrates and ranolazine as medication challenges.

SETTING

Performed at a single, tertiary-care medical center in the United States.

PARTICIPANTS

Based on the inclusion and exclusion criteria, 81 patients were included in this study. The primary outcome of the study was to measure mean pulmonary arterial pressure at rest and exertion, as well as Wasserman curves. We also recorded patient demographics and risk factors, left ventricular ejection fraction, and mean oxygen consumption. Additionally, patients were monitored symptomatically after receiving long-acting nitrates and ranolazine.

RESULTS

A total of 61 patients had resting pulmonary arterial hypertension, and 27 had EIPH. The EIPH group had a significantly higher mean age of 71.67 years. Wasserman curves calculated from the cardiopulmonary exercise testing data revealed 3 subgroups of EIPH patients: cardiac restriction, chronotropic incompetence, and combination of both patterns. The EIPH group showed significant improvement in symptoms after receiving long-acting nitrate therapy.

CONCLUSIONS

Many patients with symptoms of angina, dyspnea, and/or fatigue on exertion with negative cardiac stress testing may have underlying pulmonary arterial hypertension, including EIPH. Therefore, these patients require adequate treatment and follow-up to prevent worsening of symptoms and pathology.

Right Atrial Pressure During Exercise Predicts Survival in Patients With Pulmonary Hypertension

Background We investigated changes in right atrial pressure (RAP) during exercise and their prognostic significance in patients assessed for pulmonary hypertension (PH). Methods and Results Consecutive right heart catheterization data, including RAP recorded during supine, stepwise cycle exercise in 270 patients evaluated for PH, were analyzed retrospectively and compared among groups of patients with PH (mean pulmonary artery pressure [mPAP] ≥25 mm Hg), exercise-induced PH (exPH; resting mPAP <25 mm Hg, exercise mPAP >30 mm Hg, and mPAP/cardiac output >3 Wood Units (WU)), and without PH (noPH). We investigated RAP changes during exercise and survival over a median (quartiles) observation period of 3.7 (2.8-5.6) years. In 152 patients with PH, 58 with exPH, and 60 with noPH, median (quartiles) resting RAP was 8 (6-11), 6 (4-8), and 6 (4-8) mm Hg (P<0.005 for noPH and exPH versus PH). Corresponding peak changes (95% CI) in RAP during exercise were 5 (4-6), 3 (2-4), and -1 (-2 to 0) mm Hg (noPH versus PH P<0.001, noPH versus exPH P=0.027). RAP increase during exercise correlated with mPAP/cardiac output increase (r=0.528, P<0.001). The risk of death or lung transplantation was higher in patients with exercise-induced RAP increase (hazard ratio, 4.24; 95% CI, 1.69-10.64; P=0.002) compared with patients with unaltered or decreasing RAP during exercise. Conclusions In patients evaluated for PH, RAP during exercise should not be assumed as constant. RAP increase during exercise, as observed in exPH and PH, reflects hemodynamic impairment and poor prognosis. Therefore, our data suggest that changes in RAP during exercise right heart catheterization are clinically important indexes of the cardiovascular function.

Exercise and fluid challenge during right heart catheterisation for evaluation of dyspnoea

This prospective study compared exercise test and intravenous fluid challenge in a single right heart catheter procedure to detect latent diastolic heart failure in patients with echocardiographic heart failure with preserved ejection function. We included 49 patients (73% female) with heart failure with preserved ejection function and pulmonary artery wedge pressure ≤15 mmHg. A subgroup of 26 patients had precapillary pulmonary hypertension. Invasive haemodynamic and gas exchange parameters were measured at rest, 45° upright position, during exercise, after complete haemodynamic and respiratory recovery in lying position, and after rapid infusion of 500 mL isotonic solution. Most haemodynamic parameters increased at both exercise and intravenous fluid challenge, with the higher increase at exercise. Pulmonary vascular resistance decreased by –0.21 wood units at exercise and –0.56 wood units at intravenous fluid challenge (p = 0.3); 20% (10 of 49) of patients had an increase in pulmonary artery wedge pressure above the upper limit of 20 mmHg at exercise, and 20% above the respective limit of 18 mmHg after intravenous fluid challenge. However, only three patients exceeded the upper limit of pulmonary artery wedge pressure in both tests, i.e. seven patients only at exercise and seven other patients only after intravenous fluid challenge. In the subgroup of pulmonary hypertension patients, only two patients exceeded pulmonary artery wedge pressure limits in both tests, further five patients at exercise and four patients after intravenous fluid challenge. A sequential protocol in the same patient showed a significantly higher increase in haemodynamic parameters at exercise compared to intravenous fluid challenge. Both methods can unmask diastolic dysfunction at right heart catheter procedure, but in different patient groups.

Right Heart Catheterization During Exercise in Patients with COPD-An Overview of Clinical Results and Methodological Aspects

While right heart catheterization (RHC) at rest is the gold standard to assess pulmonary hemodynamics in patients with chronic obstructive pulmonary disease (COPD) and pulmonary hypertension (PH), the invasive measurement of exercise hemodynamics is less well established in this group. Since exercise hemodynamics are increasingly recognized as important clinical information in patients with PH, our goal was to review the literature in this field to provide a basis for clinical use, further studies, and future recommendations. We identified 69 studies (published since 1968) reporting RHC data in 2819 patients with COPD, of whom 2561 underwent exercise testing. Few studies simultaneously measured gas exchange during exercise. Overall, these studies showed large variations in the patient populations and research questions studied and the methods and definitions employed. Despite these limitations, the data consistently demonstrated the presence of precapillary PH at rest in up to 38% of patients with COPD. With exercise, a relevant proportion of patients developed an abnormal hemodynamic response, depending on the definition used. Furthermore, some studies assessed right ventricular function during exercise and showed a blunted increase in right ventricular ejection fraction. Drug effects and the impact of interventional procedures were also studied. Again, due to large variations in the patients studied and the methods used, firm conclusions are difficult to derive. Despite the limitations of this dataset, several recommendations with respect to technical aspects (body position, exercise protocol, and data acquisition) can be inferred for this challenging patient population and may be helpful for further studies or recommendations.

An official European Respiratory Society statement: pulmonary haemodynamics during exercise

There is growing recognition of the clinical importance of pulmonary haemodynamics during exercise, but several questions remain to be elucidated. The goal of this statement is to assess the scientific evidence in this field in order to provide a basis for future recommendations.

Right heart catheterisation is the gold standard method to assess pulmonary haemodynamics at rest and during exercise. Exercise echocardiography and cardiopulmonary exercise testing represent non-invasive tools with evolving clinical applications. The term “exercise pulmonary hypertension” may be the most adequate to describe an abnormal pulmonary haemodynamic response characterised by an excessive pulmonary arterial pressure (PAP) increase in relation to flow during exercise. Exercise pulmonary hypertension may be defined as the presence of resting mean PAP <25 mmHg and mean PAP >30 mmHg during exercise with total pulmonary resistance >3 Wood units. Exercise pulmonary hypertension represents the haemodynamic appearance of early pulmonary vascular disease, left heart disease, lung disease or a combination of these conditions. Exercise pulmonary hypertension is associated with the presence of a modest elevation of resting mean PAP and requires clinical follow-up, particularly if risk factors for pulmonary hypertension are present. There is a lack of robust clinical evidence on targeted medical therapy for exercise pulmonary hypertension.

Readdressing the entity of exercise pulmonary arterial hypertension

Exercise pulmonary hypertension (EPH) indicates an abnormally elevated pulmonary artery pressure (PAP) during exercise. The physiological range of PAP during exercise remains poorly defined and, therefore, a universally accepted definition of EPH remains elusive. Nevertheless, previous data concerning the distribution of PAP in normal populations and more recent retrospective clinical data enhanced our ability to define EPH. EPH can impair exercise capacity and cause dyspnea. The underlying pathophysiology of the arterial form of EPH (EPAH) appears to be similar to that seen in resting pulmonary arterial hypertension (PAH), and EPAH individuals are at risk of developing resting PAH. Patients with collagen vascular disease, especially scleroderma, are at risk for EPAH and its presence indicates a relatively poor prognosis. The prevalence of EPAH in scleroderma may be as high as 50%. The utility of pulmonary vasodilator therapy for EPAH is not well defined; however, a sizable subgroup of EPAH patients will achieve an improvement in symptoms.

Exercise-induced pulmonary hypertension by stress echocardiography: Prevalence and correlation with right heart hemodynamics

OBJECTIVES

The aim of this study was to determine the prevalence of exercise-induced pulmonary hypertension (EIPH) in consecutive subjects referred for stress echocardiography for chest pain or shortness of breath and correlate echocardiographic diagnosis of EIPH with hemodynamics at right heart catheterization (RHC).

BACKGROUND

Elevated pulmonary pressure can lead to significant morbidity and mortality. EIPH by ehocardiography has been described in patients with connective tissue disease. It's prevalence in the setting of routine clinically indicated stress echocardiography unknown.

METHODS

In a retrospective analysis of 4068 consecutive stress subjects undergoing stress echocardiography, 479 subjects with EIPH were identified. All 479 subjects with EIPH were compared to 479 age and sex matched subjects with normal pulmonary artery pressures post exercise. EIPH was defined as PASP>50mmHg or peak tricuspid regurgitation velocity>3.2m/s. Of 100 patients with EIPH who underwent RHC we identified variables which predicted abnormal hemodynamic findings on RHC.

RESULTS

The prevalence of EIPH in subjects referred for stress echocardiography was 11.7%. A greater proportion of subjects with EIPH were obese or had lung disease or connective tissue disease. Of 100 subjects who underwent RHC, 65 had abnormal results. Age>55years (OR 5.1, p<0.01]) or dilated left atrium (OR 4.4, p=0.02]) were independently associated with abnormal right heart hemodynamics.

CONCLUSIONS

The results demonstrate that 11.7% of patients undergoing clinically indicated stress echocardiography have EIPH. Of those who underwent RHC abnormal hemodynamics were significantly associated with a dilated left atrium or age older than 55years.

Echocardiography in pulmonary hypertension

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.

The Evolving Landscape of Exercise-Induced Pulmonary Hypertension

OPINION STATEMENT

Normal pulmonary artery pressures at rest, with an exaggerated rise during exercise, characterize exercise-induced pulmonary hypertension. Exercise itself as it relates to this condition is not deleterious, nor does it cause or induce disease. However much like any classical stress test, it is a physiologic probe that aids in disease unmasking. Although more work is required to establish criteria for defining this clinical entity, the phenomenon is real. It remains unknown whether it represents a nascent form of cardiopulmonary disease and whether its genesis predicts fulminant cardiopulmonary disease. Incremental cardiopulmonary exercise testing and the construction of pressure-flow plots to describe the pulmonary vascular response to exercise will be essential in defining this disease. The critical first step remains a consensus definition that will allow for further prospective study focused by a common language.

Resting pulmonary artery pressure of 21–24 mmHg predicts abnormal exercise haemodynamics

A resting mean pulmonary artery pressure (mPAP) of 21–24 mmHg is above the upper limit of normal but does not reach criteria for the diagnosis of pulmonary hypertension (PH). We sought to determine whether an mPAP of 21–24 mmHg is associated with an increased risk of developing an abnormal pulmonary vascular response during exercise.

Consecutive patients (n=290) with resting mPAP <25 mmHg who underwent invasive exercise haemodynamics were analysed. Risk factors for pulmonary vascular disease or left heart disease were present in 63.4% and 43.8% of subjects. An abnormal pulmonary vascular response (or exercise PH) was defined by mPAP >30 mmHg and total pulmonary vascular resistance >3 WU at maximal exercise.

Exercise PH occurred in 74 (86.0%) out of 86 versus 96 (47.1%) out of 204 in the mPAP of 21–24 mmHg and mPAP <21 mmHg groups, respectively (OR 6.9, 95% CI: 3.6–13.6; p<0.0001). Patients with mPAP of 21–24 mmHg had lower 6-min walk distance (p=0.002) and higher New York Heart Association functional class status (p=0.03). Decreasing levels of mPAP were associated with a lower prevalence of exercise PH, which occurred in 60.3%, 38.7% and 7.7% of patients with mPAP of 17–20, 13–16 and <13 mmHg, respectively.

In an at-risk population, a resting mPAP between 21–24 mmHg is closely associated with exercise PH together with worse functional capacity.

Novel assessment of haemodynamic kinetics with acute exercise in a rat model of pulmonary arterial hypertension

NEW FINDINGS

What is the central question of this study? The acute effect of exercise at moderately high intensity on already-elevated pulmonary arterial pressures and right ventricular wall stress in a rat model of pulmonary arterial hypertension (PAH) is unknown. What is the main finding and its importance? We show, for the first time, that in a rat model of PAH, exercise induces an acute reduction in pulmonary artery pressure associated with lung endothelial nitric oxide synthase activation, without evidence of acute right ventricular inflammation or myocyte apoptosis. Haemodynamic measures obtained with traditional invasive methodology as well as novel implantable telemetry reveal an exercise-induced 'window' of pulmonary hypertension alleviation, supporting future investigations of individualized exercise as therapy in PAH. Exercise improves outcomes of multiple chronic conditions, but controversial results, including increased pulmonary artery (PA) pressure, have prevented its routine implementation in pulmonary arterial hypertension (PAH), an incurable disease that drastically reduces exercise tolerance. Individualized, optimized exercise prescription for PAH requires a better understanding of disease-specific exercise responses. We investigated the acute impact of exercise on already-elevated PA pressure and right ventricular (RV) wall stress and inflammation in a rat model of PAH (PAH group, n = 12) induced once by monocrotaline (50 mg kg(-1) , i.p.; 2 weeks), compared with healthy control animals (n = 8). Single bouts of exercise consisted of a 45 min treadmill run at 75% of individually determined aerobic capacity (V̇O2max). Immediately after exercise, measurements of RV systolic pressure and systemic pressure were made via jugular and carotid cannulation, and were followed by tissue collection. Monocrotaline induced moderate PAH, evidenced by RV hypertrophy, decreased V̇O2max, PA muscularization, and RV and skeletal muscle cytoplasmic glycolysis detected by increased expression of glucose transporter-1. Acute exercise normalized the monocrotaline-induced elevation in RV systolic pressure and augmented pulmonary endothelial nitric oxide synthase activation, without evidence of increased RV inflammation or apoptosis. Real-time recordings of pulmonary and systemic pressures during and after single bouts of exercise made using novel implantable telemetry in the same animal for up to 11 weeks after monocrotaline (40 mg kg(-1) ) corroborated the finding of acute PA pressure decreases with exercise in PAH. The PA pressure-lowering effects of individualized exercise associated with RV-neutral effects and increases in vasorelaxor signalling encourage further development of optimized exercise regimens as adjunctive PAH therapy.

Pressure-Flow During Exercise Catheterization Predicts Survival in Pulmonary Hypertension

BACKGROUND

Pulmonary hypertension manifests with impaired exercise capacity. Our aim was to investigate whether the mean pulmonary arterial pressure to cardiac output relationship (mPAP/CO) predicts transplant-free survival in patients with pulmonary arterial hypertension (PAH) and inoperable chronic thromboembolic pulmonary hypertension (CTEPH).

METHODS

Hemodynamic data according to right heart catheterization in patients with PAH and CTEPH at rest and during supine incremental cycle exercise were analyzed. Transplant-free survival and predictive value of hemodynamics were assessed by using Kaplan-Meier and Cox regression analyses.

RESULTS

Seventy patients (43 female; 54 with PAH, 16 with CTEPH; median (quartiles) age, 65 [50; 73] years; mPAP, 34 [29; 44] mm Hg; cardiac index, 2.8 [2.3; 3.5] [L/min]/m(2)) were followed up for 610 (251; 1256) days. Survival at 1, 3, 5, and 7 years was 89%, 81%, 71%, and 59%. Age, World Health Organization-functional class, 6-min walk test, and mixed-venous oxygen saturation (but not resting hemodynamics) predicted transplant-free survival. Maximal workload (hazard ratio [HR], 0.94 [95% CI, 0.89-0.99]; P = .027), peak cardiac index (HR, 0.51 [95% CI, 0.27-0.95]; P = .034), change in cardiac index, 0.25 [95% CI, 0.06-0.94]; P = .040), and mPAP/CO (HR, 1.02 [95% CI, 1.01-1.03]; P = .003) during exercise predicted survival. Values for mPAP/CO predicted 3-year transplant-free survival with an area under the curve of 0.802 (95% CI, 0.66-0.95; P = .004).

CONCLUSIONS

In this collective of patients with PAH or CTEPH, the pressure-flow relationship during exercise predicted transplant-free survival and correlated with established markers of disease severity and outcome. Right heart catheterization during exercise may provide important complementary prognostic information in the management of pulmonary hypertension.

Exercise-induced pulmonary artery hypertension in a patient with compensated cardiac disease: hemodynamic and functional response to sildenafil therapy

We describe the case of a 54-year-old man who presented with exertional dyspnea and fatigue that had worsened over the preceding 2 years, despite a normally functioning bioprosthetic aortic valve and stable, mild left ventricular dysfunction (left ventricular ejection fraction, 0.45). His symptoms could not be explained by physical examination, an extensive biochemical profile, or multiple cardiac and pulmonary investigations. However, abnormal cardiopulmonary exercise test results and a right heart catheterization-combined with the use of a symptom-limited, bedside bicycle ergometer-revealed that the patient's exercise-induced pulmonary artery hypertension was out of proportion to his compensated left heart disease. A trial of sildenafil therapy resulted in objective improvements in hemodynamic values and functional class.

Pulmonary arterial hypertension: the key role of echocardiography

Echocardiography is a key screening tool in the diagnostic algorithm of pulmonary arterial hypertension (PAH). It provides an estimate of right ventricular function and pulmonary artery pressure, either at rest or during exercise, and is useful in ruling out secondary causes of pulmonary hypertension (PH) such as left heart disease or congenital heart disease. Several studies have showed that echocardiography is insufficiently precise as single tool for the ultimate diagnosis of PH respect to the right heart catheterization, considered the gold standard technique. Echocardiography is valuable in assessing prognosis and treatment options, monitoring the efficacy of specific therapeutic interventions, and detecting the preclinical stages of disease. The ideal imaging modality for accurate noninvasive assessment of the right heart should be accurate and precise, not influenced by loading conditions, routinely practicable and easily repeatable. For all such reasons and considering that PAH is a rare and severe condition, a complete noninvasive assessment of right heart function requires a deep knowledge of the disease and a multimodality approach.

Impairment of pulmonary vascular reserve and right ventricular systolic reserve in pulmonary arterial hypertension

Background

Exercise capacity is impaired in pulmonary arterial hypertension (PAH). We hypothesized that cardiovascular reserve abnormalities would be associated with impaired hemodynamic response to pharmacological stress and worse outcome in PAH.

Methods

Eighteen PAH patients (p) group 1 NYHA class II/III and ten controls underwent simultaneous right cardiac catheterization and intravascular ultrasound at rest and during low dose-dobutamine (10 mcg/kg/min) with trendelenburg (DST). We estimated cardiac output (CO), pulmonary vascular resistance (PVR) and capacitance (PC), and PA elastic modulus (EM). We concomitantly measured tricuspid annular plane systolic excursion (TAPSE), RV myocardial peak systolic velocity (Sm) and isovolumic myocardial acceleration (IVA) in PAH patients. Based on the rounded mean + 2 SD of the increase in mPAP in our healthy control group during DST (2.8 + 1.8 mm Hg), PAH p were divided into two groups according to mean PA pressure (mPAP) response during DST, 1: ΔmPAP > 5 mm Hg and 2: ΔmPAP ≤ 5 mm Hg. Cardiovascular reserve was estimated as the change (delta, Δ) during DST compared with rest, including ΔmPAP with respect to ΔCO (ΔmPAP/ΔCO). All patients were prospectively followed up for 2 years.

Results

PAH p showed significant lower heart rate and CO increase than controls during DST, with a significant mPAP and pulse PAP increase and higher ΔmPAP/ΔCO (p < 0.05). Neither hemodynamic, IVUS and echocardiographic data were different between both PAH groups at rest. In group 1, DST caused a higher ΔEM, ΔmPAP/ΔCO, ΔPVR, and ΔTAPSE than group 2, with a lower IVA increase and a negative ΔSV (p < 0.05). TAPSE correlated with mPAP and RVP (p < 0.05) and, IVA and Sm correlated with CO (p < 0.05). ΔEM correlated with ΔmPAP and ΔIVA with ΔCO (p < 0.05). There were two deaths/pulmonary transplantations in group 1 and one death in group 2 during the follow-up (p > 0.05).

Conclusions

Pulmonary vascular reserve and RV systolic reserve are significantly impaired in patients with PAH. The lower recruitable cardiovascular reserve is significantly related to a worse hemodynamic response to DST and it could be associated with a poor clinical outcome.

Echocardiography in pulmonary arterial hypertension: from diagnosis to prognosis

Pulmonary arterial hypertension is most often diagnosed in its advanced stages because of the nonspecific nature of early symptoms and signs. Although clinical assessment is essential when evaluating patients with suspected pulmonary arterial hypertension, echocardiography is a key screening tool in the diagnostic algorithm. It provides an estimate of pulmonary artery pressure, either at rest or during exercise, and is useful in ruling out secondary causes of pulmonary hypertension. In addition, echocardiography is valuable in assessing prognosis and treatment options, monitoring the efficacy of specific therapeutic interventions, and detecting the preclinical stages of disease.