Dobutamine stress for evaluation of right ventricular reserve in pulmonary arterial hypertension

Right ventricular dysfunction in left ventricular assist device candidates: is it time to change our prospective?

The use of left ventricular assist devices (LVAD) has significantly increased in the last years, trying to offer a therapeutic alternative to heart transplantation, in light also to the significant heart donor shortage compared to the growing advanced heart failure population. Despite technological improvements in the devices, LVAD-related mortality is still fairly high, with right heart failure being one of the predominant predictors. Therefore, many efforts have been made toward a thorough right ventricular (RV) evaluation prior to LVAD implant, considering clinical, laboratory, echocardiographic, and invasive hemodynamic parameters. However, there is high heterogeneity regarding both which predictor is the strongest as well as the relative cut-off values, and a consensus has not been reached yet, increasing the risk of facing patients in which the distinction between good or poor RV function cannot be surely reached. In parallel, due to technological development and availability of mechanical circulatory support of the RV, LVADs are being considered even in patients with suboptimal RV function. The aim of our review is to analyze the current evidence regarding the role of RV function prior to LVAD and its evaluation, pointing out the extreme variability in parameters that are currently assessed and future prospective regarding new diagnostic tools. Finally, we attempt to gather the available information on the therapeutic strategies to use in the peri-operative phase, in order to reduce the incidence of RV failure, especially in patients in which the preoperative evaluation highlighted some conflicting results with regard to ventricular function.

Pathophysiology of the right ventricle in health and disease: an update

The contribution of the right ventricle (RV) to cardiac output is negligible in normal resting conditions when pressures in the pulmonary circulation are low. However, the RV becomes relevant in healthy subjects during exercise and definitely so in patients with increased pulmonary artery pressures both at rest and during exercise. The adaptation of RV function to loading rests basically on an increased contractility. This is assessed by RV end-systolic elastance (Ees) to match afterload assessed by arterial elastance (Ea). The system has reserve as the Ees/Ea ratio or its imaging surrogate ejection fraction has to decrease by more than half, before the RV undergoes an increase in dimensions with eventual increase in filling pressures and systemic congestion. RV-arterial uncoupling is accompanied by an increase in diastolic elastance. Measurements of RV systolic function but also of diastolic function predict outcome in any cause pulmonary hypertension and heart failure with or without preserved left ventricular ejection fraction. Pathobiological changes in the overloaded RV include a combination of myocardial fibre hypertrophy, fibrosis and capillary rarefaction, a titin phosphorylation-related displacement of myofibril tension-length relationships to higher pressures, a metabolic shift from mitochondrial free fatty acid oxidation to cytoplasmic glycolysis, toxic lipid accumulation, and activation of apoptotic and inflammatory signalling pathways. Treatment of RV failure rests on the relief of excessive loading.

Hemodynamic Effects of Ketone Bodies in Patients With Pulmonary Hypertension

Background Pulmonary arterial hypertension (PAH) or chronic thromboembolic pulmonary hypertension (CTEPH) are debilitating diseases with a high mortality. Despite emerging treatments, pulmonary vascular resistance frequently remains elevated. However, the ketone body 3-hydroxybutyrate (3-OHB) may reduce pulmonary vascular resistance in these patients. Hence, the aim was to assess the hemodynamic effects of 3-OHB in patients with PAH or CTEPH. Methods and Results We enrolled patients with PAH (n=10) or CTEPH (n=10) and residual pulmonary hypertension. They received 3-OHB infusion and placebo (saline) for 2 hours in a randomized crossover study. Invasive hemodynamic and echocardiography measurements were performed. Furthermore, we investigated the effects of 3-OHB on the right ventricle of isolated hearts and isolated pulmonary arteries from Sprague-Dawley rats. Ketone body infusion increased circulating 3-OHB levels from 0.5±0.5 to 3.4±0.7 mmol/L (P<0.001). Cardiac output improved by 1.2±0.1 L/min (27±3%, P<0.001), and right ventricular annular systolic velocity increased by 1.4±0.4 cm/s (13±4%, P=0.002). Pulmonary vascular resistance decreased by 1.3±0.3 Wood units (18%±4%, P<0.001) with no significant difference in response between patients with PAH and CTEPH. In the rat studies, 3-OHB administration was associated with decreased pulmonary arterial tension compared with saline administration (maximal relative tension difference: 12±2%, P<0.001) and had no effect on right ventricular systolic pressures (P=0.63), whereas pressures rose at a slower pace (dP/dtmax, P=0.02). Conclusions In patients with PAH or CTEPH, ketone body infusion improves cardiac output and decreases pulmonary vascular resistance. Experimental rat studies support that ketone bodies relax pulmonary arteries. Long-term studies are warranted to assess the clinical role of hyperketonemia. Registration URL: https://www.clinicaltrials.gov; Unique identifier: NCT04615754.

Imaging in Pulmonary Vascular Disease-Understanding Right Ventricle-Pulmonary Artery Coupling

The right ventricle (RV) and pulmonary arterial (PA) tree are inextricably linked, continually transferring energy back and forth in a process known as RV-PA coupling. Healthy organisms maintain this relationship in optimal balance by modulating RV contractility, pulmonary vascular resistance, and compliance to sustain RV-PA coupling through life's many physiologic challenges. Early in states of adaptation to cardiovascular disease-for example, in diastolic heart failure-RV-PA coupling is maintained via a multitude of cellular and mechanical transformations. However, with disease progression, these compensatory mechanisms fail and become maladaptive, leading to the often-fatal state of "uncoupling." Noninvasive imaging modalities, including echocardiography, magnetic resonance imaging, and computed tomography, allow us deeper insight into the state of coupling for an individual patient, providing for prognostication and potential intervention before uncoupling occurs. In this review, we discuss the physiologic foundations of RV-PA coupling, elaborate on the imaging techniques to qualify and quantify it, and correlate these fundamental principles with clinical scenarios in health and disease. © 2022 American Physiological Society. Compr Physiol 12: 1-26, 2022.

Systolic and diastolic functional reserve of the subpulmonary and systemic right ventricles as assessed by pharmacologic and exercise stress: A systematic review

We performed a systematic review of the literature on the assessment of subpulmonary and systemic right ventricular (RV) functional reserve during pharmacological and exercise stress in congenital heart patients and patients with pulmonary arterial hypertension (PAH). Literature search was conducted using PubMed, EMBASE, and MEDLINE from their inception up to August 2020. Of 913 records identified, 56 studies with a total of 1730 patients were included. Of the 56 studies, 23 assessed subpulmonary RV functional reserve in repaired tetralogy of Fallot patients, 19 assessed systemic RV reserve in patients with transposition of the great arteries (TGA) after atrial switch and those with congenitally corrected TGA, and 14 assessed subpulmonary RV research in patients with PAH. Pharmacological and exercise stress was used, respectively, in 22 and 34 studies. The main findings were (1) impairment of RV systolic and diastolic functional reserve, (2) associations between impaired functional reserve and worse baseline functional parameters, and (3) prognostic implications of RV systolic functional reserve on clinical outcomes in patients with volume and/or pressure-loaded subpulmonary and systemic right ventricles. Further studies are required to establish the incremental value of incorporating stress studies of RV systolic and diastolic function in the clinical management algorithm of congenital heart patients and patients with PAH.

The physiologic basis of pulmonary arterial hypertension

Pulmonary arterial hypertension (PAH) is a rare dyspnea-fatigue syndrome caused by a progressive increase in pulmonary vascular resistance (PVR) and eventual right ventricular (RV) failure. In spite of extensive pulmonary vascular remodeling, lung function in PAH is generally well preserved, with hyperventilation and increased physiologic dead space, but minimal changes in lung mechanics and only mild to moderate hypoxemia and hypocapnia. Hypoxemia is mainly caused by a low mixed venous PO₂ from a decreased cardiac output. Hypocapnia is mainly caused by an increased chemosensitivity. Exercise limitation in PAH is cardiovascular rather than ventilatory or muscular. The extent of pulmonary vascular disease in PAH is defined by multipoint pulmonary vascular pressure-flow relationships with a correction for hematocrit. Pulsatile pulmonary vascular pressure-flow relationships in PAH allow for the assessment of RV hydraulic load. This analysis is possible either in the frequency-domain or in the time-domain. The RV in PAH adapts to increased afterload by an increased contractility to preserve its coupling to the pulmonary circulation. When this homeometric mechanism is exhausted, the RV dilates to preserve flow output by an additional heterometric mechanism. Right heart failure is then diagnosed by imaging of increased right heart dimensions and clinical systemic congestion signs and symptoms. The coupling of the RV to the pulmonary circulation is assessed by the ratio of end-systolic to arterial elastances, but these measurements are difficult. Simplified estimates of RV-PA coupling can be obtained by magnetic resonance or echocardiographic imaging of ejection fraction.

Low-Dose Dobutamine Stress Echocardiography for the Early Detection of Pulmonary Arterial Hypertension in Selected Patients with Systemic Sclerosis Whose Resting Echocardiography Is Non-Diagnostic for Pulmonary Hypertension

BACKGROUND

Dobutamine stress echocardiography (DSE) has limited application in systemic sclerosis (SSc). We examined DSE usefulness in revealing pulmonary arterial hypertension (PAH) in selected SSc patients whose resting echocardiography for pulmonary hypertension (PH) was non-diagnostic.

METHODS

Forty SSc patients underwent right heart catheterization (RHC) and, simultaneously, low-dose DSE (incremental doses up to 20 μg/kg/min). Inclusion criteria were: preserved left and right ventricular (RV) function (tricuspid annulus plane systolic excursion [TAPSE] ≥ 16 mm and tissue Doppler imaging-derived systolic velocity of tricuspid annulus [RVS'] > 10 cm/s), normal pulmonary function tests, and baseline maximal tricuspid regurgitation (TR) velocity of 2.7-3.2 m/s.

RESULTS

Of 36 patients who completed DSE, resting RHC diagnosed PAH in 12 patients (33.3%). At 20 μg/kg/min, patients with PAH had higher TR velocity, higher pulmonary arterial pressure measured by RHC, and lower RV inotropic response compared with patients without PAH. A cut-off value of maximal TR velocity >3.1 m/s had a sensitivity of 80%, a specificity of 84.2%, and an accuracy of 82.4% for the detection of PAH.

CONCLUSIONS

Low-dose DSE has a satisfactory diagnostic accuracy for the early detection of PAH in highly selected SSc patients whose baseline echocardiographic measurements for PH lie in the gray zone.

Under Pressure: Right Heart Catheterization and Provocative Testing for Diagnosing Pulmonary Hypertension

Pulmonary hypertension (PH) is a heterogenous disorder involving multiple pathophysiological processes that ultimately affect the vasculature within the lungs. Right heart catheterization (RHC) continues to be the benchmark for diagnosing PH. The use of provocation techniques during RHC can help sub-characterize the type of PH and thus assist in developing appropriate treatment strategies for the management of each PH subtype. This review examines proven and novel approaches for evaluating the pulmonary vasculature during RHC and aspires to provide an accurate, clinically relevant framework for using RHC to diagnose and manage PH. Further improvement in standardized protocols will help optimize the application of RHC in patients with PH.

The Role of Exercise Doppler Echocardiography to Unmask Pulmonary Arterial Hypertension in Selected Patients with Systemic Sclerosis and Equivocal Baseline Echocardiographic Values for Pulmonary Hypertension

Recently, a lower mean pulmonary arterial pressure (PAP) cutoff of >20 mmHg for pulmonary hypertension (PH) definition has been proposed. We examined whether exercise Doppler echocardiography (EDE) can unmask PA hypertension (PAH) in systemic sclerosis (SSc) patients whose baseline echocardiography for PH is equivocal. We enrolled 49 patients with SSc who underwent treadmill EDE. Tricuspid regurgitation (TR) velocity was recorded immediately after EDE. Inotropic reserve of right ventricle (RV) was assessed by the change (post-prior to exercise) of tissue Doppler imaging-derived peak systolic velocity (S) of tricuspid annulus. Inclusion criteria comprised preserved left and RV function, and baseline TR velocity between 2.7 and 3.2 m/s. All patients had right-heart catheterization (RHC) within 48 h after EDE. From 46 patients with good quality of post-exercise TR velocity, RHC confirmed PAH in 21 (45.6%). Post-exercise TR velocity >3.4 m/s had a sensitivity of 90.5%, a specificity of 80% and an accuracy of 84.8% in detecting PAH. Inotropic reserve of RV was positively correlated with maximum achieved workload in METs (r = 0.571, p < 0.001). EDE has a good diagnostic accuracy for the identification of PAH in selected SSc patients whose baseline echocardiographic measurements for PH lie in the gray zone, and it is also potentially useful in assessing RV contractile reserve.

Diagnosis and Treatment of Right Heart Failure in Pulmonary Vascular Diseases: A National Heart, Lung, and Blood Institute Workshop

Right ventricular dysfunction is a hallmark of advanced pulmonary vascular, lung parenchymal, and left heart disease, yet the underlying mechanisms that govern (mal)adaptation remain incompletely characterized. Owing to the knowledge gaps in our understanding of the right ventricle (RV) in health and disease, the National Heart, Lung, and Blood Institute (NHLBI) commissioned a working group to identify current challenges in the field. These included a need to define and standardize normal RV structure and function in populations; access to RV tissue for research purposes and the development of complex experimental platforms that recapitulate the in vivo environment; and the advancement of imaging and invasive methodologies to study the RV within basic, translational, and clinical research programs. Specific recommendations were provided, including a call to incorporate precision medicine and innovations in prognosis, diagnosis, and novel RV therapeutics for patients with pulmonary vascular disease.

Neurohormonal modulation in pulmonary arterial hypertension

Pulmonary hypertension is a fatal condition of elevated pulmonary pressures, complicated by right heart failure. Pulmonary hypertension appears in various forms; one of those is pulmonary arterial hypertension (PAH) and is particularly characterised by progressive remodelling and obstruction of the smaller pulmonary vessels. Neurohormonal imbalance in PAH patients is associated with worse prognosis and survival. In this back-to-basics article on neurohormonal modulation in PAH, we provide an overview of the pharmacological and nonpharmacological strategies that have been tested pre-clinically and clinically. The benefit of neurohormonal modulation strategies in PAH patients has been limited by lack of insight into how the neurohormonal system is changed throughout the disease and difficulties in translation from animal models to human trials. We propose that longitudinal and individual assessments of neurohormonal status are required to improve the timing and specificity of neurohormonal modulation strategies. Ongoing developments in imaging techniques such as positron emission tomography may become helpful to determine neurohormonal status in PAH patients in different disease stages and optimise individual treatment responses.

Exercise right ventricular ejection fraction predicts right ventricular contractile reserve

BACKGROUND

Right ventricular (RV) contractile reserve shows promise as an indicator of occult RV dysfunction in pulmonary vascular disease. We investigated which measure of RV contractile reserve during exercise best predicts occult RV dysfunction and clinical outcomes.

METHODS

We prospectively studied RV contractile reserve in 35 human subjects referred for right heart catheterization for known or suspected pulmonary hypertension. All underwent cardiac magnetic resonance imaging, echocardiography, and supine invasive cardiopulmonary exercise testing with concomitant RV pressure-volume catheterization. Event-free survival was prospectively adjudicated from time of right heart catheterization for a 4-year follow-up period.

RESULTS

RV contractile reserve during exercise, as measured by a positive change in end-systolic elastance (Ees) during exertion, was associated with elevation in pulmonary pressures but preservation of RV volumes. Lack of RV reserve, on the other hand, was tightly coupled with acute RV dilation during exertion (R² = 0.76, p< 0.001). RV Ees and dilation changes each predicted resting RV-PA dysfunction. RV ejection fraction during exercise, which captured exertional changes in both RV Ees and RV dilation, proved to be a robust surrogate for RV contractile reserve. Reduced exercise RV ejection fraction best predicted occult RV dysfunction among a variety of resting and exercise RV measures, and was also associated with clinical worsening.

CONCLUSIONS

RV ejection fraction during exercise, as an index of RV contractile reserve, allows for excellent identification of occult RV dysfunction, more so than resting measures of RV function, and may predict clinical outcomes as well.

Selection of the Optimal Candidate to MitraClip for Secondary Mitral Regurgitation: Beyond Mitral Valve Morphology

Secondary mitral regurgitation (MR) occurs despite structurally normal valve apparatus due to an underlying disease of the myocardium leading to disruption of the balance between tethering and closing forces with ensuing failure of leaflet coaptation. In patients with heart failure (HF) and left ventricular dysfunction, secondary MR is independently associated with poor outcome, yet prognostic benefits related to the correction of MR have remained elusive. Surgery is not recommended for the correction of secondary MR outside coronary artery bypass grafting. Percutaneous mitral valve repair (PMVR) with MitraClip implantation has recently evolved as a new transcatheter treatment option of inoperable or high-risk patients with severe MR, with promising results supporting the extension of guideline recommendations. MitraClip is highly effective in reducing secondary MR in HF patients. However, the derived clinical benefit is still controversial as two randomized trials directly comparing PMVR vs. optimal medical therapy in severe secondary MR yielded virtually opposite conclusions. We reviewed current evidence to identify predictors of PMVR-related outcomes in secondary MR useful to improve the timing and the selection of patients who would derive maximal benefit from MitraClip intervention. Beyond mitral valve anatomy, optimal candidate selection should rely on a comprehensive diagnostic workup and a fine-tuned risk stratification process aimed at (i) recognizing the substantial heterogeneity of secondary MR and its complex interaction with the myocardium, (ii) foreseeing hemodynamic consequences of PMVR, (iii) anticipating futility and (iv) improving symptoms, quality of life and overall survival.

Impact of right ventricular contractile reserve during low-load exercise on exercise intolerance in heart failure

AIMS

Traditional criteria for heart transplantation by cardiopulmonary exercise testing (CPX) include peak oxygen uptake (VO₂ ) < 14 mL/kg/min. Reaching a sufficient exercise load is challenging for patients with refractory heart failure (HF) because of their exercise intolerance. Recently, a substantial impact of right ventricular (RV) dysfunction was highlighted on urgent heart transplantation and mortality. This study aims to investigate the impact of RV contractile reserve, assessed by low-load exercise stress echocardiography (ESE), on exercise intolerance defined as peak VO₂  < 14 mL/kg/min, in patients with HF.

METHODS AND RESULTS

We prospectively examined 67 consecutive patients hospitalized for HF who underwent ESE and CPX under a stabilized HF condition. Although low-load ESE was defined as 25 W load exercise, an increment in RV systolic (s') velocity was regarded as the preservation of RV contractile reserve. All patients completed low-load ESE. During low-load ESE, the variation in RV s' velocity significantly correlated with peak VO₂ (r = 0.787, P < 0.001). The change in RV s' velocity during low-load ESE accurately identified patients with peak VO₂  < 14 mL/kg/min (area under the curve, 0.95; sensitivity, 92%; specificity, 85%). The intraclass correlation coefficient for intra-observer and inter-observer agreement for the change in RV s' velocity was 0.96 (95% confidence interval, 0.88-0.99, P < 0.001) and 0.86 (95% confidence interval, 0.64-0.95, P < 0.001), respectively. The RV-to-pulmonary circulation (PC) coupling, which was assessed by the slope of the relationship between RV s' velocity and pulmonary artery systolic pressure at rest and low-load exercise, was worse in the low-peak VO₂ group (<14 mL/kg/min) than the preserved-peak VO₂ group (≥14 mL/kg/min).

CONCLUSIONS

The change in RV s' velocity during low-load ESE could estimate the exercise capacity in HF patients. The assessments of RV contractile reserve and RV-to-PC coupling could be clinically beneficial to distinguish high-risk HF patients.

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

OBJECTIVES

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

The Utility of Cardiac Reserve for the Early Detection of Cancer Treatment-Related Cardiac Dysfunction: A Comprehensive Overview

With progressive advancements in cancer detection and treatment, cancer-specific survival has improved dramatically over the past decades. Consequently, long-term health outcomes are increasingly defined by comorbidities such as cardiovascular disease. Importantly, a number of well-established and emerging cancer treatments have been associated with varying degrees of cardiovascular injury that may not emerge until years following the completion of cancer treatment. Of particular concern is the development of cancer treatment related cardiac dysfunction (CTRCD) which is associated with an increased risk of heart failure and high risk of morbidity and mortality. Early detection of CTRCD appears critical for preventing long-term cardiovascular morbidity in cancer survivors. However, current clinical standards for the identification of CTRCD rely on assessments of cardiac function in the resting state. This provides incomplete information about the heart's reserve capacity and may reduce the sensitivity for detecting sub-clinical myocardial injury. Advances in non-invasive imaging techniques have enabled cardiac function to be quantified during exercise thereby providing a novel means of identifying early cardiac dysfunction that has proved useful in several cardiovascular pathologies. The purpose of this narrative review is (1) to discuss the different non-invasive imaging techniques that can be used for quantifying different aspects of cardiac reserve; (2) discuss the findings from studies of cancer patients that have measured cardiac reserve as a marker of CTRCD; and (3) highlight the future directions important knowledge gaps that need to be addressed for cardiac reserve to be effectively integrated into routine monitoring for cancer patients exposed to cardiotoxic therapies.

Pulmonary Hypertension and Right Ventricular Failure: Lung Transplant Versus Heart-Lung Transplant

Pulmonary arterial hypertension is a highly morbid disease with limited treatment options that improve survival and currently the only curative treatment is transplantation. There is a small body of literature comparing the efficacy of lung and heart-lung transplantation in this population. The bulk of evidence suggests that most patients with severe right ventricular failure undergoing transplant will have recovery of right ventricular function after lung transplantation. Existing data suggest that, in the absence of complex congenital heart disease or significant left ventricular dysfunction, double-lung transplant is the surgical procedure of choice.

Safety and Utility of Cardiopulmonary Exercise Testing in Arrhythmogenic Right Ventricular Cardiomyopathy/Dysplasia

Background

Arrhythmogenic right ventricular cardiomyopathy/dysplasia (ARVC/D) is characterized by high arrhythmic burden and progressive heart failure, which can prompt referral for heart transplantation. Cardiopulmonary exercise testing (CPET) has an established role in risk stratification for advanced heart failure therapies, but has not been described in ARVC/D. This study sought to determine the safety and prognostic utility of CPET in patients with ARVC/D.

Methods and Results

Using the Johns Hopkins ARVC/D Registry, we examined patients with ARVC/D undergoing CPET. Baseline characteristics and transplant‐free survival were compared on the basis of peak oxygen consumption (pVO2) (≤14 or >14 mL/kg per minute) and ventilatory efficiency (Ve/VCO₂ slope ≤34 or >34). Thirty‐eight patients underwent 50 CPETs. There were no sustained arrhythmic events. Twenty‐nine patients achieved a maximal test. Patients with pVO2 ≤14 mL/kg per minute were more often men (P=0.042) compared with patients with pVO2 >14 mL/kg per minute. Patients with Ve/VCO₂ slope >34 tended to have more moderate/severe right ventricular dilation (7/9 [78%] versus 10/26 [38%]; P=0.060) and clinical heart failure (8/9 [89%] versus 13/26 [50%]; P=0.056) compared with patients with Ve/VCO₂ slope ≤34. Patients who underwent heart transplantation were more likely to have clinical heart failure (10/10 [100%] versus 13/28 [46%]; P=0.003). Patients with Ve/VCO₂ slope >34 had worse transplant‐free survival compared with patients with Ve/VCO₂ slope ≤34 (n=35; hazard ratio, 6.57 [95% CI, 1.28–33.72]; log‐rank P=0.010), whereas transplant‐free survival was similar on the basis of pVO2 groups (n=29; hazard ratio, 3.38 [95% CI, 0.75–15.19]; log‐rank P=0.092).

Conclusions

CPET is safe to perform in patients with ARVC/D. Ve/VCO₂ slope may be used for risk stratification and guide referral for heart transplantation in ARVC/D.

State-of-the-Art Review: Echocardiography in Pulmonary Hypertension

Pulmonary hypertension is a progressive and often fatal disease that frequently presents with dyspnoea on exertion and results in increased right ventricular afterload and right ventricular failure. Although cardiac catheterisation is required for a formal diagnosis, transthoracic echocardiography (TTE) has a central role as a screening tool in those with symptoms and those at risk for developing pulmonary vascular disease. Echocardiographic techniques can be employed to estimate pulmonary artery pressure and resistance, right atrial pressure as well as to derive indirect information about right heart structure and function. Potential causes for pulmonary hypertension may also be identified such as congenital heart disease or left ventricular diastolic dysfunction. An increasing body of evidence has demonstrated the important prognostic utility of echocardiographic data in pulmonary hypertension and highlighted the potential for TTE to help clinicians understand whether treatment responses have been adequate or an escalation in therapy is necessary, as therapeutic options continue to expand for patients with pulmonary arterial hypertension. Although traditional echocardiographic techniques only allow surrogate measures of right ventricular systolic function due to the complex shape of the chamber, newer techniques have enabled three-dimensional assessment of the right ventricle to assess right ventricular volume and contractility. This review will discuss traditional methods as well as newer echocardiographic methods in the setting of pulmonary hypertension.

Exercise-Induced Changes in Pulmonary Artery Stiffness in Pulmonary Hypertension

Background: Pulmonary hypertension causes pulmonary artery (PA) stiffening, which overloads the right ventricle (RV). Since symptoms of pulmonary hypertension (PH) are exacerbated by exercise, exercise-induced PA stiffening is relevant to cardiopulmonary status. Here, we sought to demonstrate the feasibility of using magnetic resonance imaging (MRI) for non-invasive assessment of exercise-induced changes in PA stiffness in patients with PH.

Methods: MRI was performed on 7 PH patients and 8 age-matched control subjects at rest and during exercise stress. Main pulmonary artery (MPA) relative area change (RAC) and pulse wave velocity (PWV) were measured from 2D-PC images. Invasive right heart catheterization (RHC) was performed on 5 of the PH patients in conjunction with exercise stress to measure MPA pressures and stiffness index (β).

Results: Heart rate and cardiac index (CI) were significantly increased with exercise in both groups. In controls, RAC decreased from 0.27 ± 0.05 at rest to 0.22 ± 0.06 with exercise (P < 0.05); a modest increase in PWV was not significant (P = 0.06). In PH patients, RAC decreased from 0.15 ± 0.02 to 0.11 ± 0.01 (P < 0.05) and PWV and β increased from 3.9 ± 0.54 m/s and 1.86 ± 0.12 at rest to 5.75 ± 0.70 m/s and 3.25 ± 0.26 with exercise (P < 0.05 for both), respectively. These results confirm increased MPA stiffness with exercise stress in both groups and the non-invasive metrics of MPA stiffness correlated well with β. Finally, as assessed by PWV but not RAC, PA stiffness of PH patients increased more than that of controls for comparable levels of moderate exercise.

Conclusion: These results demonstrate the feasibility of using MRI for non-invasive assessment of exercise-induced changes in MPA stiffness in a small, heterogeneous group of PH patients in a research context. Similar measurements in a larger cohort are required to investigate differences between PWV and RAC for estimation of MPA stiffness.

Influence of impaired right ventricular contractile reserve on exercise capacity in patients with precapillary pulmonary hypertension: A study with exercise stress echocardiography

OBJECTIVES

Right ventricular (RV) contractile reserve reflects the ability of RV to accommodate the increased afterload and may play an essential role in the evaluation of precapillary pulmonary hypertension (PH). This study aimed to assess RV contractile reserve based on exercise stress echocardiography (ESE) and to determine the echocardiographic determinants of exercise capacity in patients with precapillary PH.

METHODS

A total of 31 patients with precapillary PH and 15 age- and sex-matched healthy control subjects were prospectively recruited. All subjects underwent ESE to assess RV function at rest and under peak exercise. Changes in these parameters during exercise were calculated to quantify the RV contractile reserve. Patients with precapillary PH also underwent cardiopulmonary exercise test (CPET), and data pertaining to peak oxygen uptake (peak VO₂ ) and minute ventilation/carbon dioxide production (VE/VCO₂ ) were collected.

RESULTS

Right ventricular contractile reserve including change in tricuspid annular plane systolic excursion (∆TAPSE), change in RV fractional area change (∆RVFAC), and change in Doppler-derived tricuspid lateral annular peak systolic velocity (∆S') was significantly depressed in precapillary PH patients compared with control subjects (P < 0.05). Parameters of RV function and RV contractile reserve were markedly associated with maximal exercise capacity (P < 0.05). ∆RVFAC was an independent predictor of peak VO₂ (r²  = 0.601, P < 0.05).

CONCLUSIONS

Assessment of RV contractile reserve facilitates identification of subclinical dysfunction and evaluation of clinical status and severity of precapillary PH. ESE as a noninvasive method may provide a comprehensive clinical assessment and facilitate therapeutic decision-making for these patients.

The Right Heart-Pulmonary Circulation Unit: Physiopathology

The most common cause of right heart failure is increased afterload caused by pulmonary hypertension. Right ventricular function adaptation to increased afterload is basically systolic, with secondary increase in dimensions and systemic congestion. Increased right ventricular dimensions and decreased ejection fraction are associated with a decreased survival in severe pulmonary hypertension. Targeted therapies titrated to reverse the right ventricular remodeling dimensions improve survival in severe pulmonary hypertension.

Echocardiography during preload stress for evaluation of right ventricular contractile reserve and exercise capacity in pulmonary hypertension

OBJECTIVES

Pulmonary hypertension (PH) is characterized by marked and sustained elevation of pulmonary vascular resistance and pulmonary artery pressure, and subsequent right-sided heart failure. Right ventricular (RV) function and exercise capacity have been recognized as important prognostic factors for PH. Our aim was to investigate RV contractile reserve and exercise capacity during a leg-positive pressure (LPP) maneuver.

METHODS

The study population comprised 43 PH patients and 17 normal controls. All patients underwent echocardiography at rest and during LPP stress. Exercise capacity was assessed by 6-minute walk distance for PH patients. RV relative wall thickness was calculated from dividing by RV free wall thickness by basal RV linear dimensions at end-diastole. RV function was calculated by averaging peak speckle-tracking longitudinal strain from the RV free wall. RV contractile reserve was assessed as the difference in RV free wall strain at rest and during LPP stress. Changes in left ventricular stroke volume (ΔSV) during LPP stress were also calculated.

RESULTS

ΔSV and RV contractile reserve of PH patients were significantly lower than of controls (3.6 ± 6.0 mL vs 8.5 ± 2.3 mL, and 8.2 ± 11.9% vs 14.5 ± 6.6%; both P < 0.01). RV contractile reserve of PH patients with ΔSV <3.3 mL was significantly lower than of PH patients with ΔSV >3.3 mL (3.9 ± 13.2% vs 12.3 ± 8.9%; P = 0.02). ΔSV had also significant correlation with 6-minute walk distance (r = 0.42, P = 0.006). Multivariate regression analysis showed that RV relative wall thickness was an independent determinant parameter of ΔSV during LPP stress for PH patients (β = 3.2, P = 0.003).

CONCLUSIONS

Preload stress echocardiography in response to LPP maneuver, a noninvasive and easy-to-use procedure for routine clinical use, proved to be useful for the assessment of RV contractile reserve and exercise capacity of PH patients.

Impaired right ventricular reserve predicts adverse cardiac outcomes in adults with congenital right heart disease

Objective

The prevalence of heart failure (HF) among adult patients with congenital heart disease (ACHD) is rising. Right ventricle (RV) exercise reserve and its relationship to outcomes have not been characterised. We aim to evaluate the prognostic impact of impaired RV reserve in an ACHD population referred for cardiopulmonary exercise testing (CPET).

Methods

This retrospective study evaluates patients with ACHD who underwent CPET (n=147) with first-pass radionuclide ventriculography at a single tertiary care centre. RV reserve was categorised as normal, mild to moderately or severely impaired. The primary composite clinical outcome included clinical right HF, arrhythmia, transplantation or death.

Results

Patients were median age 41±13 years, 50% were female and median follow-up was 1.1 (IQR: 0.7–2.0) years. Exercise RV reserve was impaired in 103 patients (70%), of whom 32% were asymptomatic. Resting RV systolic function poorly predicted RV reserve, with 52% of patients with severe impairment having a qualitatively normal echocardiographic assessment. The severely impaired reserve group had lower peak oxygen consumption (VO2)(17.2 vs 22.5 mL/kg/min, p<0.0001) compared with the normal reserve group, and was more likely to develop the composite outcome (48% vs 9%, log-rank p<0.001). Severely impaired RV reserve predicted event-free survival after adjusting for peak VO2, age, sex, RV pathology, QRS duration, New York Heart Association class, resting RV ejection fraction and RV dilation by echocardiography or MRI (HR 3.7, 95% CI 1.1 to 13.0, p=0.039).

Conclusion

Impaired RV reserve, occurred in asymptomatic patients, was not well predicted by resting systolic function assessment, and strongly predicted adverse cardiovascular outcomes.

Dobutamine stress echocardiography in pulmonary arterial hypertension

BACKGROUND

There is a growing interest in exploring the concept of right ventricular functional reserve in patients with pulmonary arterial hypertension. However, it is still unclear how it should be assessed. Aim of the study was to investigate the determinants of the changes in cardiac output and in pulmonary pressure during dobutamine stress echocardiography in pulmonary arterial hypertension.

METHODS

Low-dose dobutamine stress echocardiography was performed in 55 patients and 28 controls. Tricuspid annular plane systolic excursion, its ratio to systolic pulmonary artery pressure, right ventricular area change, degree of tricuspid regurgitation, right ventricular end-systolic pressure-area ratio, cardiac output were assessed at rest and at peak stress.

RESULTS

According to the stress induced increase in cardiac output, patients were classified into 2 groups: above/equal to the median of 2.8 L/min (high cardiac output) or below the median (low cardiac output). High cardiac output patients were characterized by a greater increase in heart rate (+45.1 ± 17.5 vs +21.3 ± 17.7 bpm), a greater improvement in tricuspid annular plane systolic excursion (+4.2 ± 3.3 vs +1.9 ± 2.6 mm, P = 0.005) and a decrease in tricuspid regurgitation (P = 0.010) as compared to low cardiac output patients. Changes in pulmonary pressure were not associated with changes in indicators of right ventricular function but only with changes in heart rate.

CONCLUSIONS

The increase in cardiac output during dobutamine is associated with an improvement in longitudinal right ventricular function, a decrease in tricuspid regurgitation and an increase in heart rate. Changes in pulmonary pressure only reflect the changes in heart rate.

Exercise and the right ventricle: a potential Achilles' heel

Exercise is associated with unequivocal health benefits and results in many structural and functional changes of the myocardium that enhance performance and prevent heart failure. However, intense exercise also presents a significant hemodynamic challenge in which the right-sided heart chambers are exposed to a disproportionate increase in afterload and wall stress that can manifest as myocardial fatigue or even damage if intense exercise is sustained for prolonged periods. This review focuses on the physiological factors that result in a disproportionate load on the right ventricle during exercise and the long-term consequences. The changes in cardiac structure and function that define 'athlete's heart' disproportionately affect the right-sided heart chambers and this can raise important diagnostic overlap with some cardiac pathologies, particularly some inherited cardiomyopathies. The interaction between exercise and arrhythmogenic right ventricular cardiomyopathy (ARVC) will be highlighted as an important example of how hemodynamic stressors can combine with deficiencies in cardiac structural elements to cause cardiac dysfunction predisposing to arrhythmias. The extent to which extreme exercise can cause adverse remodelling in the absence of a genetic predisposition remains controversial. In the athlete with profound changes in heart structure, it can be extremely challenging to determine whether common symptoms such as palpitations may be a marker of more sinister arrhythmias. This review discusses some of the techniques that have recently been proposed to identify pathology in these circumstances. Finally, we will discuss recent evidence defining the role of exercise restriction as a therapeutic intervention in individuals predisposed to arrhythmogenic cardiomyopathy.

Safety of regadenoson stress testing in patients with pulmonary hypertension

OBJECTIVES

We sought to determine the safety of regadenoson stress testing in patients with PH.

BACKGROUND

PH is increasingly recognized at more advanced ages. As many as one-third of patients with PH have coronary artery disease. Because of their physical limitations, patients with PH are unable to adequately exercise. Regadenoson can potentially have an adverse impact due to their tenuous hemodynamics. Current guidelines suggest performing a coronary angiography in patients with PH who have angina or multiple coronary risk factors.

METHODS

We identified 67 consecutive patients with confirmed PH by catheterization (mean PA > 25 mmHg not due to left heart disease) who underwent MPI with regadenoson stress. Medical records were reviewed to determine hemodynamic and ECG response to regadenoson.

RESULTS

No serious events occurred. Common side effects related to regadenoson were observed, dyspnea being the most common (70.6%). No syncope occurred. Heart rate increased from 74.6 ± 14 to 96.3 ± 18.3 bpm, systolic blood pressure increased from 129.8 ± 20.9 to 131.8 ± 31 mmHg, and diastolic blood pressure decreased from 77.1 ± 11.4 to 72.9 ± 15.3 mmHg. There was no ventricular tachycardia, ventricular fibrillation, or second- or third-degree atrioventricular block.

CONCLUSION

Regadenoson stress MPI appears to be well tolerated and safe in patients with PH.

Usefulness of scoring right ventricular function for assessment of prognostic factors in patients with chronic thromboembolic pulmonary hypertension

Right ventricular (RV) function is associated with prognosis in chronic thromboembolic pulmonary hypertension (CTEPH). This study aimed to establish an RV dysfunction score using RV echocardiographic parameters to clarify the clinical characteristics in patients with CTEPH and to compare RV dysfunction score with parameters such as World Health Organization (WHO) functional class, hemodynamics, exercise capacity, and plasma BNP level. We enrolled 35 inpatients with CTEPH (mean age, 62 ± 15 years, 15 males). We constructed ‘an RV dysfunction score’ calculated as the summation of each point awarded for the presence of four parameters: tricuspid annular plane systolic excursion (TAPSE) < 16 mm, 1 point; tissue Doppler-derived tricuspid lateral annular systolic velocity (S′) < 10 cm/s, 1 point; right ventricular fractional area change (RVFAC) < 35%, 1 point; and right ventricular myocardial performance index (RV-MPI) > 0.4, 1 point. TAPSE, S′, RVFAC, and RV-MPI was 18.7 ± 4.8 mm, 11.9 ± 3.1 cm/s, 33.5 ± 13.9%, and 0.39 ± 0.2, respectively. The RV dysfunction score was associated with symptom [WHO functional class (p = 0.026)], hemodynamics [mean PAP (p = 0.01), cardiac index (p = 0.009), pulmonary vascular resistance (p = 0.001), and SvO₂ (p = 0.039)], exercise capacity [6-min walk distance (p = 0.046), peakVO₂ (p = 0.016), and VE/VCO₂ slope (p = 0.031)], and plasma BNP level (p = 0.005). This RV dysfunction score using the four RV echocardiographic parameters could be a simple and useful scoring system to evaluate prognostic factors in patients with CTEPH.

Stressing the Cardiopulmonary Vascular System: The Role of Echocardiography

The cardiopulmonary vascular system represents a key determinant of prognosis in several cardiorespiratory diseases. Although right heart catheterization is considered the gold standard for assessing pulmonary hemodynamics, a comprehensive noninvasive evaluation including left and right ventricular reserve and function and cardiopulmonary interactions remains highly attractive. Stress echocardiography is crucial in the evaluation of many cardiac conditions, typically coronary artery disease but also heart failure and valvular heart disease. In stress echocardiographic applications beyond coronary artery disease, the assessment of the cardiopulmonary vascular system is a cornerstone. The possibility of coupling the left and right ventricles with the pulmonary circuit during stress can provide significant insight into cardiopulmonary physiology in healthy and diseased subjects, can support the diagnosis of the etiology of pulmonary hypertension and other conditions, and can offer valuable prognostic information. In this state-of-the-art document, the topic of stress echocardiography applied to the cardiopulmonary vascular system is thoroughly addressed, from pathophysiology to different stress modalities and echocardiographic parameters, from clinical applications to limitations and future directions.

Left ventricular end-diastolic dimension and septal e' are predictors of cardiac index at rest, while tricuspid annular plane systolic excursion is a predictor of peak oxygen uptake in patients with pulmonary hypertension

Little is known regarding a correlation of hemodynamics at rest or exercise capacity with echocardiographic parameters in patients with pulmonary hypertension (PH). To clarify these potential correlations, we performed transthoracic echocardiography, right heart catheterization, and cardiopulmonary exercise testing in 53 patients with pulmonary arterial hypertension (PAH) and chronic thromboembolic pulmonary hypertension (CTEPH). Left ventricular end-diastolic dimension (LVDd), early diastolic velocity of the septal mitral annulus (septal e'), tricuspid regurgitation peak gradient (TRPG), and tricuspid annular plane systolic excursion (TAPSE) were significantly correlated with cardiac index (LVDd; r = 0.477, P < 0.001, septal e'; r = 0.463, P = 0.001, TRPG; r = - 0.455, P = 0.001 and TAPSE; r = 0.406, P = 0.003, respectively). Multiple regression analysis revealed that LVDd and septal e' were significantly associated with cardiac index (CI) and stroke volume index at rest. Among the exercise capacity markers evaluated, TAPSE, TRPG, and LVDd were significantly correlated with peak oxygen uptake (TAPSE; r = 0.534, P < 0.001, TRPG; r = - 0.466, P = 0.001 and LVDd; r = 0.411, P = 0.002, respectively). Multiple regression analysis showed that TAPSE was significantly associated with peak oxygen uptake (VO₂). In PAH and CTEPH patients, LVDd and septal e' were significantly associated with CI at rest, whereas TAPSE was significantly associated with peak VO₂. Echocardiographic parameters may predict the prognostic factors of PAH and CTEPH patients.

Non-invasive imaging of global and regional cardiac function in pulmonary hypertension

Pulmonary hypertension (PH) is a progressive illness characterized by elevated pulmonary artery pressure; however, the main cause of mortality in PH patients is right ventricular (RV) failure. Historically, improving the hemodynamics of pulmonary circulation was the focus of treatment; however, it is now evident that cardiac response to a given level of pulmonary hemodynamic overload is variable but plays an important role in the subsequent prognosis. Non-invasive tests of RV function to determine prognosis and response to treatment in patients with PH is essential. Although the right ventricle is the focus of attention, it is clear that cardiac interaction can cause left ventricular dysfunction, thus biventricular assessment is paramount. There is also focus on the atrial chambers in their contribution to cardiac function in PH. Furthermore, there is evidence of regional dysfunction of the two ventricles in PH, so it would be useful to understand both global and regional components of dysfunction. In order to understand global and regional cardiac function in PH, the most obvious non-invasive imaging techniques are echocardiography and cardiac magnetic resonance imaging (CMRI). Both techniques have their advantages and disadvantages. Echocardiography is widely available, relatively inexpensive, provides information regarding RV function, and can be used to estimate RV pressures. CMRI, although expensive and less accessible, is the gold standard of biventricular functional measurements. The advent of 3D echocardiography and techniques including strain analysis and stress echocardiography have improved the usefulness of echocardiography while new CMRI technology allows the measurement of strain and measuring cardiac function during stress including exercise. In this review, we have analyzed the advantages and disadvantages of the two techniques and discuss pre-existing and novel forms of analysis where echocardiography and CMRI can be used to examine atrial, ventricular, and interventricular function in patients with PH at rest and under stress.

Heart Failure Is Common and Under-Recognized in Patients With Arrhythmogenic Right Ventricular Cardiomyopathy/Dysplasia

BACKGROUND

Heart failure (HF) prevalence in arrhythmogenic right ventricular cardiomyopathy/dysplasia (ARVC/D) varies depending on study cohort and is not well characterized. This study sought to determine prevalence and predictors of HF in ARVC/D.

METHODS AND RESULTS

Clinical HF, defined as at least 1 HF sign or symptom, was retrospectively adjudicated for 289 patients meeting ARVC/D Task Force Criteria. HF was present in 142 patients (49%): 113 had isolated RV involvement and 29 had evidence of LV dysfunction. Average age of HF onset was 40±14 years. Most commonly reported symptoms were exertional dyspnea (78%) and fatigue (73%). Only 40% (n=57/142) had signs of volume overload. Left-sided HF signs were rare. Patients with clinical HF before ARVC/D diagnosis (n=31) were older (P=0.005) and met fewer Task Force Criteria (P=0.013) than those who developed HF after ARVC/D presentation. Female sex (odds ratio, 2.2; 95% confidence interval, 1.21-4.01; P=0.01) and lateral precordial T-wave inversions (odds ratio, 9.87; 95% confidence interval, 1.07-91.1; P=0.043) were associated with increased odds of HF. Additionally, patients with symptomatic LV dysfunction had higher odds of lateral precordial T-wave inversions (odds ratio, 18.4; 95% confidence interval, 2.92-116.18; P=0.002). Patients with HF were more likely to undergo heart transplantation (15/142 versus 1/147; P<0.001) or die during study follow-up period (7 versus 0; P=0.007).

CONCLUSIONS

HF symptoms, especially exertional dyspnea, are common in ARVC/D; yet, classic left-sided signs are typically absent and less than half have evidence of volume overload. Given the unique predominately right-sided phenotype, a large portion of patients with HF may be under-recognized.

Dobutamine stress MRI in pulmonary hypertension: relationships between stress pulmonary artery relative area change, RV performance, and 10-year survival

In pulmonary hypertension (PH), right ventricular (RV) performance determines survival. Pulmonary artery (PA) stiffening is an important biomechanical event in PH and also predicts survival based on the PA relative area change (RAC) measured at rest using magnetic resonance imaging (MRI). In this exploratory study, we sought to generate novel hypotheses regarding the influence of stress RAC on PH prognosis and the interaction between PA stiffening, RV performance and survival. Fifteen PH patients underwent dobutamine stress-MRI (ds-MRI) and right heart catheterization. RAC_REST, RAC_STRESS, and ΔRAC (RAC _STRESS - RAC _REST) were correlated against resting invasive hemodynamics and ds-MRI data regarding RV performance and RV-PA coupling efficiency (n'_vv [RV stroke volume/RV end-systolic volume]). The impact of RAC, RV data, and n'_vv on ten-year survival were determined using Kaplan-Meier analysis. PH patients with a low ΔRAC (<-2.6%) had a worse long-term survival (log-rank P = 0.045, HR for death = 4.46 [95% CI = 1.08-24.5]) than those with ΔRAC ≥ -2.6%. Given the small sample, these data should be interpreted with caution; however, low ΔRAC was associated with an increase in stress diastolic PA area indicating proximal PA stiffening. Associations of borderline significance were observed between low RAC_STRESS and low n'_vvSTRESS, Δη'_VV, and ΔRVEF. Further studies are required to validate the potential prognostic impact of ΔRAC and the biomechanics potentially connecting low ΔRAC to shorter survival. Such studies may facilitate development of novel PH therapies targeted to the proximal PA.

Right heart-pulmonary circulation unit and cardiac resynchronization therapy

Clinical response to cardiac resynchronization therapy (CRT) has been known for years to be highly variable, with a spectrum of responses from no change or even deterioration of cardiac function to spectacular improvements. In the plethora of clinical, echocardiographic, biohumoral, and electrophysiological predictors of response to CRT and postimplant issues besides patient selection, the role of right ventricular (RV) function has been largely overlooked. In reviewing current evidence, we noticed conflicting results between observational studies and randomized trials not only concerning the impact of baseline RV function on CRT efficacy but also on the effects of CRT on RV size and function. Hence, we aimed to provide a critical reappraisal of current knowledge and unresolved issues on the reciprocal interactions between RV function and CRT, shifting the spotlight on the concept of right heart pulmonary circulation unit and on the clinical and prognostic significance of impaired ventricular-arterial coupling reserve. In this viewpoint, we propose that (1) CRT should not be denied to potential candidate because of "isolated" RV dysfunction and (2) assessment of baseline right heart pulmonary circulation unit and its dynamic response to pharmacological stress should be considered in future studies, as well as in the preimplant evaluation of individual candidates among other clinical factors.

Dose–Response Head-to-Head Comparison of Inodilators Dobutamine, Milrinone, and Levosimendan in Chronic Experimental Pulmonary Hypertension

The choice of inodilator drug in the acute management of patients with pulmonary hypertension (PH) having right ventricular (RV) failure remains unsettled and challenging. Comprehensive experimental evaluations may provide further insight and fundamental translational research clues to support inodilator selection and clinical trial design. Our aim was to compare acute dose–response hemodynamic effects of inodilators dobutamine (DOB), milrinone (MIL), and levosimendan (LEV) in chronic experimental PH. Seven-week-old male Wistar rats were randomly injected with 60 mg·kg−1 monocrotaline (MCT) or vehicle (Ctrl, n = 7) and underwent systemic and pulmonary artery (PA) pressure and RV pressure–volume (PV) hemodynamic evaluation under halogenate anesthesia 24 to 30 days after injection. The MCT-injected animals (n = 7 each) randomly received dose–response infusions of DOB (1, 3, 6 and 12 μg·kg−1·min−1), MIL (MIL: 1, 3, 6 and 12 μg·kg−1·min−1), or LEV (0.3, 0.6, 1.2 and 2.4 μg·kg−1·min−1). Load-independent indexes were obtained by inferior vena cava occlusion at baseline and after the last dose. All inodilators increased RV ejection fraction, preload recruitable stroke work, and ventricular–vascular coupling without jeopardizing perfusion pressure. Dobutamine raised heart rate and PA pressure. Only LEV increased cardiac index and decreased PA elastance and pulmonary vascular resistance (PVR). Moreover, only LEV downward-shifted the end-diastolic PV relationship, thereby improving RV compliance. Adding sildenafil to LEV further decreased PVR. Levosimendan had beneficial acute systolic and diastolic functional effects in experimental chronic PH and RV afterload compared to DOB and MIL. It should be further tested in clinical trials enrolling patients with PH in the perioperative and critical care settings.

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.