Non-Invasive Assessment of Pulmonary Vascular Resistance in Pulmonary Hypertension: Current Knowledge and Future Direction

Right Ventricular Limitation: A Tale of Two Elastances

Right ventricular (RV) dysfunction is a commonly considered cause of low cardiac output in critically ill patients. Its management can be difficult and requires an understanding of how the RV limits cardiac output. We explain that RV stroke output is caught between the passive elastance of the RV walls during diastolic filling and the active elastance produced by the RV in systole. These two elastances limit RV filling and stroke volume and consequently limit left ventricular stroke volume. We emphasize the use of the term "RV limitation" and argue that limitation of RV filling is the primary pathophysiological process by which the RV causes hemodynamic instability. Importantly, RV limitation can be present even when RV function is normal. We use the term "RV dysfunction" to indicate that RV end-systolic elastance is depressed or diastolic elastance is increased. When RV dysfunction is present, RV limitation occurs at lowerpulmonary valve opening pressures and lower stroke volume, but stroke volume and cardiac output still can be maintained until RV filling is limited. We use the term "RV failure" to indicate the condition in which RV output is insufficient for tissue needs. We discuss the physiological underpinnings of these terms and implications for clinical management.

Impact of pulmonary hypertension on arteriovenous fistula failure of hemodialysis patients: A 10 years follow-up cohort study

BACKGROUND

Pulmonary hypertension (PH) is common in patients with end-stage renal disease (ESRD). Arteriovenous fistulas (AVF) creation may involve in the pathogenesis of PH. The aim of this study was to explore the impact of PH after AVF creation on the AVF failure rate in maintenance hemodialysis (MHD) patients.

METHODS

From January 1, 2009, to January 1, 2019, we retrospectively collected data of 578 MHD patients in Guangdong Provincial People's Hospital Blood Purification Center, China. Patients were followed-up until AVF failure or death or May 25, 2020. According to the systolic pulmonary artery pressure (SPAP) within 1 year after the establishment of AVF, the MHD patients were divided into three groups: SPAP ⩽ 35 mmHg, 35 < SPAP < 45 mmHg, SPAP ⩾ 45 mmHg. The primary outcome was AVF failure defined as AVF cannot complete hemodialysis. The secondary outcomes were all-cause mortality.

RESULTS

A total of 578 patients were analyzed. The average age was 60.66 ± 15.34 years (58.1% men). Of these, 26.1% of patients were reported PH. The SPAP exhibited a left-skewed nonparametric distribution and the overall SPAP after the creation of AVF was 39.00 (29.00-52.00) mmHg. The median follow-up was 5.8 (5.5-6.3) years. Overall, 12.8% (74/578) patients were reported AVF failure events. There was no significant difference in AVF failure rate among three groups (p = 0.070). A total of 111 (19.2%) died during the follow-up period. Compared with the SPAP ⩽35 mmHg group, only the all-cause death rate significantly increased in MHD patients with PH (p < 0.001).

CONCLUSIONS

The secondary pulmonary hypertension after AVF creation did not increase the risk of AVF failure in MHD patients, but significantly increased the risk of mortality for this portion of the patients. Future larger sample sizes, multi-center, and prospective trials are needed to make sure which type of access will benefit on their survival for MHD patients with SPAP ⩾35 mmHg.

Pulmonary hypertension in remote and disadvantaged population: overcoming unique challenges for improved outcomes

Pulmonary hypertension (PH) is a common and debilitating medical condition with high mortality. PH research has traditionally focused on pulmonary arterial hypertension and its management in expert PH centres. Other forms of PH such as PH associated with cardiac or respiratory disease are more common, less well-understood and associated with higher mortality. Epidemiology of PH in disadvantaged, remote and rural regions, remains largely undocumented. In this review, we discuss the unique challenges in identifying PH in rural and disadvantaged populations using the Top End region of the Northern Territory of Australia as an example. We propose a simple diagnostic approach, ideally suited to regions where resource allocation is scarce, using clinical skills, echocardiography, and an escalation algorithm. The brief history, epidemiology and current literature on PH are summarised to inform the busy clinicians. We highlight two case examples from the Top End to illustrate the challenges and potential solutions.

Hemodynamic assessment and risk classification for successful weaning of Impella in patients with cardiogenic shock

BACKGROUND

Clinical predictors for successful weaning of patients from Impella heart pump have not been clarified. We aimed to elucidate the relationship between pulmonary artery catheter (PAC) parameters at the time of Impella weaning and subsequent outcomes.

METHODS

We enrolled consecutive patients who had received Impella for cardiogenic shock. PAC data were collected immediately before Impella weaning. Patients were classified as non-survivors if they died or required any mechanical circulatory support reintroduction within 30 days of weaning.

RESULTS

Of 81 patients enrolled, 61 underwent Impella weaning. Of these, 16 were non-survivors. Predictive indicators of non-survival were high pulmonary artery wedge pressure (PAWP; hazard ratio [HR] per 5 mmHg 1.97, 95% CI 1.35-2.80; p < 0.001), high mean pulmonary artery pressure (MPAP; HR per 5 mmHg 1.90, 1.38-2.58; p < 0.001), and low cardiac power output (CPO; HR per 0.1 Watts 0.71, 0.52-0.92; p = 0.006). Cutoff values of PAWP 20 mmHg, MPAP 22 mmHg, and CPO 0.59 Watts showed strong associations with 30-day non-survival risk (low risk 8% in patients with low PAWP and high CPO or 4% in patients with low MPAP and high CPO; high risk 100% in patients with high PAWP and low CPO or 82% in patients with high MPAP and low CPO).

CONCLUSIONS

PAWP or MPAP higher than the cutoff with CPO below the cutoff at Impella weaning were associated with worse outcomes. We proposed a risk classification model for successful Impella weaning using PAC.

Echocardiographic, Biochemical, and Electrocardiographic Correlates Associated With Progressive Pulmonary Arterial Hypertension

Background: Pulmonary arterial hypertension (PAH) is a progressive proliferative vasculopathy associated with mechanical and electrical changes, culminating in increased vascular resistance, right ventricular (RV) failure, and death. With a main focus on invasive tools, there has been an underutilization of echocardiography, electrocardiography, and biomarkers to non-invasively assess the changes in myocardial and pulmonary vascular structure and function during the course of PAH. Methods: A SU5416-hypoxia rat model was used for inducing PAH. Biventricular functions were measured using transthoracic two-dimensional (2D) echocardiography/Doppler (echo/Doppler) at disease onset (0 week), during progression (3 weeks), and establishment (5 weeks). Similarly, electrocardiography was performed at 0, 3, and 5 weeks. Invasive hemodynamic measurements and markers of cardiac injury in plasma were assessed at 0, 3, and 5 weeks. Results: Increased RV systolic pressure (RVSP) and rate of isovolumic pressure rise and decline were observed at 0, 3, and 5 weeks in PAH animals. EKG showed a steady increase in QT-interval with progression of PAH, whereas P-wave height and RS width were increased only during the initial stages of PAH progression. Echocardiographic markers of PAH progression and severity were also identified. Three echocardiographic patterns were observed: a steady pattern (0-5 weeks) in which echo parameter changed progressively with severity [inferior vena cava (IVC) expiratory diameter and pulmonary artery acceleration time (PAAT)], an early pattern (0-3 weeks) where there is an early change in parameters [RV fractional area change (RV-FAC), transmitral flow, left ventricle (LV) output, estimated mean PA pressure, RV performance index, and LV systolic eccentricity index], and a late pattern (3-5 weeks) in which there is only a late rise at advanced stages of PAH (LV diastolic eccentricity index). RVSP correlated with PAAT, PAAT/PA ejection times, IVC diameters, RV-FAC, tricuspid systolic excursion, LV systolic eccentricity and output, and transmitral flow. Plasma myosin light chain (Myl-3) and cardiac troponin I (cTnI) increased progressively across the three time points. Cardiac troponin T (cTnT) and fatty acid-binding protein-3 (FABP-3) were significantly elevated only at the 5-week time point. Conclusion: Distinct electrocardiographic and echocardiographic patterns along with plasma biomarkers were identified as useful non-invasive tools for monitoring PAH progression.

Left ventricular global longitudinal strain predicts elevated cardiac pressures and poor clinical outcomes in patients with non-ischemic dilated cardiomyopathy

BACKGROUND

Risk stratification in patients with non-ischemic dilated cardiomyopathy (NI-DCM) is essential to treatment planning. Global longitudinal strain (GLS) predicts poor prognosis in various cardiac diseases, but it has not been evaluated in a cohort of exclusively NI-DCM. Although deformation parameters have been shown to reflect diastolic function, their association with other hemodynamic parameters needs further elucidation. We aimed to evaluate the association between GLS and E/GLS and invasive hemodynamic parameters and assess the prognostic value of GLS and E/GLS in a prospective well-defined pure NI-DCM cohort.

METHODS AND RESULTS

Forty-one patients with NI-DCM were enrolled in the study. They underwent a standard diagnostic workup, including transthoracic echocardiography and right heart catheterization. During a five-year follow-up, 20 (49%) patients reached the composite outcome measure: LV assist device implantation, heart transplantation, or cardiovascular death. Pulmonary capillary wedge pressure (PCWP), mean pulmonary artery pressure, pulmonary vascular resistance (PVR) correlated with GLS and E/GLS (p < 0.05). ROC analysis revealed that GLS and E/GLS could identify elevated PCWP (≥ 15 mmHg) and PVR (> 3 Wood units). Survival analysis showed GLS and E/GLS to be associated with short- and long-term adverse cardiac events (p < 0.05). GLS values above thresholds of -5.34% and -5.96% indicated 18- and 12-fold higher risk of poor clinical outcomes at one and five years, respectively. Multivariate Cox regression analysis revealed that GLS is an independent long-term outcome predictor.

CONCLUSION

GLS and E/GLS correlate with invasive hemodynamics parameters and identify patients with elevated PCWP and high PVR. GLS and E/GLS predict short- and long-term adverse cardiac events in patients with NI-DCM. Worsening GLS is associated with incremental risk of long-term adverse cardiac events and might be used to identify high-risk patients.

Animal models of pulmonary hypertension: Getting to the heart of the problem

Despite recent therapeutic advances, pulmonary hypertension (PH) remains a fatal disease due to the development of right ventricular (RV) failure. At present, no treatments targeted at the right ventricle are available, and RV function is not widely considered in the preclinical assessment of new therapeutics. Several small animal models are used in the study of PH, including the classic models of exposure to either hypoxia or monocrotaline, newer combinational and genetic models, and pulmonary artery banding, a surgical model of pure RV pressure overload. These models reproduce selected features of the structural remodelling and functional decline seen in patients and have provided valuable insight into the pathophysiology of RV failure. However, significant reversal of remodelling and improvement in RV function remains a therapeutic obstacle. Emerging animal models will provide a deeper understanding of the mechanisms governing the transition from adaptive remodelling to a failing right ventricle, aiding the hunt for druggable molecular targets.

Preload dependence of pulmonary haemodynamics and right ventricular performance

AIMS

Systolic pulmonary artery pressure (SPAP) and right heart adaptation in relation to pre-existing preload are often disregarded. To determine volume-related changes in the pulmonary-right ventricle (RV) unit and the preload dependence of its components, we analysed pulmonary haemodynamics and right ventricular performance, taking advantage of the plasma volume removal associated to haemodialysis (HD).

METHODS AND RESULTS

Fifty-three stable patients on chronic HD with LVEF > 50% and without heart failure were recruited (mean age 63.0 ± 12.4 years; 31.2% women; hypertension in 89% and diabetes in 53%) and evaluated just before and after HD (mean ultrafiltration volume 2.4 ± 0.7 l). SPAP from both times were available in 39 patients. After HD, SPAP decreased (42.2 ± 12.6 to 33.7 ± 11.6 mmHg, p < 0.001) without modification of non-invasive pulmonary vascular resistance (1.75 ± 0.44 to 1.75 ± 0.40 eWU, p = 0.94). Age and drop in the E/e' ratio were the variables associated with greater reduction in PASP (p = 0.022 and p = 0.049, respectively). A significant reduction of right chamber sizes was observed, along with a diminution in measures of RV contractility, excluding RV longitudinal strain. Functional tricuspid regurgitation (FTR) diminution was observed in 26% of patients, occurring in every case with more than mild FTR. On multivariate analyses, left atrial size was the only predictor of pulmonary hypertension (defined as SPAP > 40 mmHg) (OR 1.29 (1.07-1.56), p = 0.006).

CONCLUSION

Rapid volemic changes may affect FTR grading, RV size and contractility, with RV longitudinal strain being less variable than conventional parameters. SPAP decreases after HD, and this reduction is related to age and greater diminution of the E/e' ratio.

Serum uric acid is associated with disease severity and may predict clinical outcome in patients of pulmonary arterial hypertension secondary to connective tissue disease in Chinese: a single-center retrospective study

Background

Previous studies have shown that serum uric acid (UA) levels are correlated with the severity of idiopathic pulmonary arterial hypertension (IPAH) and are predictors of disease prognosis. Still, few studies have explored the value of serum UA in pulmonary arterial hypertension secondary to connective tissue disease (CTD-PAH). This retrospective study aimed to investigate the clinical value of serum UA levels in patients with CTD-PAH.

Methods

Fifty CTD-PAH patients were enrolled in our study, from which baseline UA levels, respective variations, and additional clinical data were collected. The potential association between baseline UA level and severity of CTD-PAH was investigated. Furthermore, the relationship between baseline UA and survival rate of CTD-PAH patients, as well as between UA variations and survival rate of pulmonary hypertension secondary to connective tissue disease (CTD-PH) patients was discussed.

Results

Baseline serum UA levels were positively correlated with pulmonary vascular resistance (PVR). During the follow-up period, 3 CTD-PAH and 12 CTD-PH patients died. Kaplan-Meier survival curves showed lower survival rate in patients with hyperuricemia than in patients with normouricemia, in both groups (CTD-PAH group p = 0.041, CTD-PH group p = 0.013). Concerning serum UA variations, patients with persistent hyperuricemia showed the lowest survival rate when compared with patients with steady normouricemia (p = 0.01) or patients with decresing serum UA levels, i.e. undergoing from a status of hyperuricemia to a status of normouricemia (p = 0.023).

Conclusion

Baseline serum UA levels might predict severity of CTD-PAH. Together with baseline values, changes of uric acid level may predict the clinical prognosis of the disease.

Comparison of Human and Experimental Pulmonary Veno-Occlusive Disease

Pulmonary veno-occlusive disease (PVOD) occurs in humans either as a heritable form (hPVOD) due to biallelic inactivating mutations of EIF2AK4 (encoding GCN2) or as a sporadic form in older age (sPVOD). The chemotherapeutic agent mitomycin C (MMC) is a potent inducer of PVOD in humans and in rats (MMC-PVOD). Here, we compared human hPVOD and sPVOD, and MMC-PVOD pathophysiology at the histological, cellular, and molecular levels to unravel common altered pathomechanisms. MMC exposure in rats was associated primarily with arterial and microvessel remodeling, and secondarily by venous remodeling, when PVOD became symptomatic. In all forms of PVOD tested, there was convergent GCN2-dependent but eIF2α-independent pulmonary protein overexpression of HO-1 (heme oxygenase 1) and CHOP (CCAAT-enhancer-binding protein [C/EBP] homologous protein), two downstream effectors of GCN2 signaling and endoplasmic reticulum stress. In human PVOD samples, CHOP immunohistochemical staining mainly labeled endothelial cells in remodeled veins and arteries. Strong HO-1 staining was observed only within capillary hemangiomatosis foci, where intense microvascular proliferation occurs. HO-1 and CHOP stainings were not observed in control and pulmonary arterial hypertension lung tissues, supporting the specificity for CHOP and HO-1 involvement in PVOD pathobiology. In vivo loss of GCN2 (EIF2AK4 mutations carriers and Eif2ak4^-/- rats) or in vitro GCN2 inhibition in cultured pulmonary artery endothelial cells using pharmacological and siRNA approaches demonstrated that GCN2 loss of function negatively regulates BMP (bone morphogenetic protein)-dependent SMAD1/5/9 signaling. Exogenous BMP9 was still able to reverse GCN2 inhibition-induced proliferation of pulmonary artery endothelial cells. In conclusion, we identified CHOP and HO-1 inhibition, and BMP9, as potential therapeutic options for PVOD.

Top End Pulmonary Hypertension Study: Understanding Epidemiology, Therapeutic Gaps and Prognosis in Remote Australian Setting

INTRODUCTION

The Top End of Australia has a high proportion of Indigenous people with a high burden of chronic cardiac and pulmonary diseases likely to contribute to pulmonary hypertension (PH). The epidemiology of PH has not been previously studied in this region.

METHODS

Patients with PH were identified from the Northern Territory echocardiography database from January 2010 to December 2015 and followed to the end of 2019 or death. Pulmonary hypertension was defined as a tricuspid regurgitation velocity ≥2.75 m/s measured by Doppler echocardiography. The aetiology of PH, as categorised by published guidelines, was determined by reviewing electronic health records.

RESULTS

1,764 patients were identified comprising 49% males and 45% Indigenous people. The prevalence of PH was 955 per 100,000 population (with corresponding prevalence of 1,587 for Indigenous people). Hypertension, atrial fibrillation, diabetes and respiratory disease were present in 85%, 45%, 41% and 39%, respectively. Left heart disease was the leading cause for PH (58%), the majority suffering from valvular disease (predominantly rheumatic). Pulmonary arterial hypertension (PAH), respiratory disease related PH, chronic thromboembolic PH (CTEPH) and unclear multifactorial PH represented 4%, 16%, 2% and 3%, respectively. Underlying causes were not identifiable in 17% of the patients. Only 31% of potentially eligible patients were on PAH-specific therapy. At census, there was 40% mortality, with major predictors being age, estimated pulmonary artery systolic pressure (ePASP) and Indigenous ethnicity.

CONCLUSION

Pulmonary hypertension is prevalent in Northern Australia, with a high frequency of modifiable risk factors and other treatable conditions. Whether earlier diagnosis, interpretation and intervention improve outcomes merits further assessment.

Pulmonary hypertension in low- and middle-income countries with focus on sub-Saharan Africa

Pulmonary hypertension (PH) is a devastating, progressive disease with increasingly debilitating symptoms and usually shortened overall life expectancy. This article reviews the global epidemiology of PH with focus on low- and middle-income countries (LMICs) and sub-Sahara African in particular. Although left ventricular heart disease is the most common cause globally, the main contributing risk factors in LMICs are chronic infectious diseases especially human immunodeficiency virus (HIV) and schistosomiasis. Other important risk factors of PH are rheumatic heart disease, untreated congenital heart disease (CHD), and sickle cell disease. Despite existing epidemiological data of PH risk factors suggesting a high prevalence in sub-Saharan Africa (SSA), the available literature is limited. International registries in LMICs like the pan African pulmonary hypertension cohort (PAPUCO) study are essential to provide information about the causes, treatment, outcome, and the natural course of PH in Africa and other parts of the world. In addition, there is a need to track diagnostic and management practices in order to develop suitable algorithms to diagnose PH in LMICs.

Cardiovascular magnetic resonance 4D flow analysis has a higher diagnostic yield than Doppler echocardiography for detecting increased pulmonary artery pressure

Background

Pulmonary hypertension is definitively diagnosed by the measurement of mean pulmonary artery (PA) pressure (mPAP) using right heart catheterization. Cardiovascular magnetic resonance (CMR) four-dimensional (4D) flow analysis can estimate mPAP from blood flow vortex duration in the PA, with excellent results. Moreover, the peak systolic tricuspid regurgitation (TR) pressure gradient (TRPG) measured by Doppler echocardiography is commonly used in clinical routine to estimate systolic PA pressure. This study aimed to compare CMR and echocardiography with regards to quantitative and categorical agreement, and diagnostic yield for detecting increased PA pressure.

Methods

Consecutive clinically referred patients (n = 60, median [interquartile range] age 60 [48–68] years, 33% female) underwent echocardiography and CMR at 1.5 T (n = 43) or 3 T (n = 17). PA vortex duration was used to estimate mPAP using a commercially available time-resolved multiple 2D slice phase contrast three-directional velocity encoded sequence covering the main PA. Transthoracic Doppler echocardiography was performed to measure TR and derive TRPG. Diagnostic yield was defined as the fraction of cases in which CMR or echocardiography detected an increased PA pressure, defined as vortex duration ≥15% of the cardiac cycle (mPAP ≥25 mmHg) or TR velocity > 2.8 m/s (TRPG > 31 mmHg).

Results

Both CMR and echocardiography showed normal PA pressure in 39/60 (65%) patients and increased PA pressure in 9/60 (15%) patients, overall agreement in 48/60 (80%) patients, kappa 0.49 (95% confidence interval 0.27–0.71). CMR had a higher diagnostic yield for detecting increased PA pressure compared to echocardiography (21/60 (35%) vs 9/60 (15%), p < 0.001). In cases with both an observable PA vortex and measurable TR velocity (34/60, 56%), TRPG was correlated with mPAP (R² = 0.65, p < 0.001).

Conclusions

There is good quantitative and fair categorical agreement between estimated mPAP from CMR and TRPG from echocardiography. CMR has higher diagnostic yield for detecting increased PA pressure compared to echocardiography, potentially due to a lower sensitivity of echocardiography in detecting increased PA pressure compared to CMR, related to limitations in the ability to adequately visualize and measure the TR jet by echocardiography. Future comparison between echocardiography, CMR and invasive measurements are justified to definitively confirm these findings.

Echocardiographic evolution of pulmonary hypertension in female patients with hyperthyroidism

Objective:

The objective of this study was to highlight the impact of increased cardiac output (CO) and/or pulmonary vascular resistance (PVR) on the occurrence and evolution of pulmonary hypertension (PH) in hyperthyroidism and to follow their evolution in patients under therapy.

Methods:

Our study group consisted of 142 women with hyperthyroidism of different severities and etiologies. We divided our patients into three groups: groups A (overt hyperthyroidism), B (recurrent disease), and C (subclinical forms). We performed echocardiography to determine echocardiographically estimated systolic pulmonary arterial pressure (eePAP), CO, and PVR before and at 3, 6, and 12 months after treatment with thyroid suppression therapy and beta-blockers.

Results:

In our study group we documented PH of various severities in 73 patients (51.4%). Increased CO, induced mostly by hyperthyroidism-specific tachycardia, was frequently detected in overt hyperthyroidism and also augmented PVR, as documented in 43.66% of patients with severe and recurrent forms. For all patients with PH, we emphasized a strong correlation between eePAP and PVR level (r=0.854, p<0.0001) and a moderate one with CO (r=0.437, p<0.0001) and with hyperthyroidism duration (r=0.545, p<0.0001). Under therapy, CO rapidly normalized and PVR significantly decreased in groups A and C. In group B, the reduction was modest and statistically significant.

Conclusion:

The pathophysiological mechanisms responsible for the occurrence of PH are elevated CO and PVR. While increased CO is rapidly alleviated under therapy, elevated eePAP and PVR persist in recurrent cases and are responsible for the perpetuation of PH.

Effects of human relaxin-2 (serelaxin) on hypoxic pulmonary vasoconstriction during acute hypoxia in a sheep model

Purpose

Hypoxia induces pulmonary vasoconstriction with a subsequent increase of pulmonary artery pressure (PAP), which can result in pulmonary hypertension. Serelaxin has shown an increase of pulmonary hemodynamic parameters after serelaxin injection. We therefore investigated the response of pulmonary hemodynamic parameters after serelaxin administration in a clinically relevant model.

Methods

Six controls and six sheep that received 30 μg/kg serelaxin underwent right heart catheterization during a 12-minute hypoxia period (inhalation of 5% oxygen and 95% nitrogen) and subsequent reoxygenation. Systolic, diastolic, and mean values of both PAP (respectively, PAPs, PAPd, and PAPm) and pulmonary capillary wedge pressure (respectively, PCWPs, PCWPd, and PCWPm), blood gases, heart rate (HR), and both peripheral and pulmonary arterial oxygen saturation were obtained. Cardiac output (CO), stroke volume (SV), pulmonary vascular resistance (PVR), pulmonary arterial compliance (PAcompl), and systemic vascular resistance (SVR) were calculated.

Results

The key findings of the current study are that serelaxin prevents the rise of PAPs (p≤0.001), PAPm, PCWPm, PCWPs (p≤0.03), and PAPd (p≤0.05) during hypoxia, while it simultaneously increases CO and SV (p≤0.001). Similar courses of decreases of PAPm, PAPd, PAPs, CO, SVR (p≤0.001), and PCWPd (p≤0.03) as compared to hypoxic values were observed during reoxygenation. In direct comparison, the experimental groups differed during hypoxia in regard to HR, PAPm, PVR, and SVR (p≤0.03), and during reoxygenation in regard to HR (p≤0.001), PAPm, PAPs, PAPd, PVR, SVR (p≤0.03), and PCWPd (p≤0.05).

Conclusion

The findings of this study suggest that serelaxin treatment improves pulmonary hemodynamic parameters during acute hypoxia.

Pulmonary vascular resistance determines mortality in end-stage renal disease patients with pulmonary hypertension

The multifactorial etiology of pulmonary hypertension (PH) in end-stage renal disease (ESRD) includes patients with and without elevated pulmonary vascular resistance (PVR). We explored the prognostic implication of this distinction by evaluating pretransplant ESRD patients who underwent right heart catheterization and echocardiography. Demographics, clinical data, and test results were analyzed. All-cause mortality data were obtained. Median follow-up was 4 years. Of the 150 patients evaluated, echocardiography identified 99 patients (66%) with estimated pulmonary artery (PA) systolic pressure > 36 mm Hg, which correlated poorly with mortality (HR = 1.28, 95% CI 0.72-2.27, P = .387). Right heart catheterization identified 88 (59%) patients with mean PA pressure ≥ 25 mm Hg. Of these, 70 had PVR ≤ 3 Wood units and 18 had PVR > 3 Wood units. Survival analysis demonstrated a significant prognostic effect of an elevated PVR in patients with high mean PA pressures (HR = 2.26, 95% CI 1.07-4.77, P = .03), while patients with high mean PA pressure and normal PVR had equivalent survival to those with normal PA pressure. Despite the high prevalence of PH in ESRD patients, elevated PVR is uncommon and is a determinant of prognosis in patients with PH. Patients with normal PVR had survival equivalent to those with normal PA pressures.

Pulmonary hemodynamic effects and pulmonary arterial compliance during hypovolemic shock and reinfusion with human relaxin-2 (serelaxin) treatment in a sheep model

BACKGROUND

Previous studies on the recombinant form of human relaxin-2 (serelaxin) have shown a decrease of pulmonary hemodynamics after serelaxin injection. Currently, the effect of serelaxin treatment during hypovolemia in a large animal model remains mostly unknown.

METHODS

12 sheep were randomly assigned to a sham or serelaxin (30μg/kg serelaxin) group and underwent right heart catheterization. 50% of the estimated total blood volume were removed to induce hypovolemia, and subsequently retransfused 20 min later (reinfusion). Blood gases, heart rate, peripheral and pulmonary arterial oxygen saturation, systolic, diastolic and mean values of both pulmonary artery pressure (PAP) and pulmonary capillary wedge pressure (PCW) were measured. Cardiac output (CO), pulmonary vascular resistance (PVR), pulmonary arterial compliance (PAcompl) and systemic vascular resistance (SVR) were calculated.

RESULTS

Hypovolemia and shock led to a similar decrease of PAP and PCW in both groups (p≤0.001). CO, SV and PAcompl decreased only in the control group (p≤0.05) and remained higher in the serelaxin-treated group. The results of this study suggest that serelaxin treatment did not negatively influence hemodynamic parameters during hypovolemic shock.

CONCLUSION

The main conclusion of this study is that cardiopulmonary adaption mechanisms are not critically altered by serelaxin administration during severe hypovolemia and retransfusion.