Right ventricular response to pulsatile load is associated with early right heart failure and mortality after left ventricular assist device

Right Ventricular Pressure Waveform Analysis-Clinical Relevance and Future Directions

Continuous measurement of pressure in the right atrium and pulmonary artery has commonly been used to monitor right ventricular function in critically ill and surgical patients. This approach is largely based upon the assumption that right atrial and pulmonary arterial pressures provide accurate surrogates for diastolic filling and peak right ventricular pressures, respectively. However, due to both technical and physiologic factors, this assumption is not always true. Accordingly, recent studies have begun to emphasize the potential clinical value of also measuring right ventricular pressure at the bedside. This has highlighted both past and emerging research demonstrating the utility of analyzing not only the amplitude of right ventricular pressure but also the shape of the pressure waveform. This brief review summarizes data demonstrating that combining conventional measurements of right ventricular pressure with variables derived from waveform shape allows for more comprehensive and ideally continuous bedside assessment of right ventricular function, particularly when combined with stroke volume measurement or 3D echocardiography, and discusses the potential use of right ventricular pressure analysis in computational models for evaluating cardiac function.

Pulmonary arterial compliance as a measure of right ventricular loading in mitral regurgitation

Pulmonary hypertension (PH) is a common and prognostically important complication of mitral regurgitation (MR). Mean pulmonary arterial pressure (mPAP) and pulmonary vascular resistance (PVR) are traditionally used to diagnose PH, however these indices measure static rather than pulsatile load, leading to an incomplete representation of pulmonary vascular load on the right ventricle (RV). Pulmonary arterial compliance (PAC) is one method for quantifying pulsatile load, and is both a stronger predictor of prognosis in left heart failure, as well as a more sensitive measure of early pulmonary vascular dysfunction than PVR. With the expansion of transcatheter mitral and tricuspid valve therapies, there is renewed interest to more accurately define the load imposed by the pulmonary vasculature on the RV, especially in the early phase, prior to the onset of chronic PH. This review discusses the pathophysiology of pH in left heart failure and MR, the utility of PAC as a measure of RV afterload, and its calculation for clinical use and interpretation, underlining the utility of PAC as an adjunct for assessing pulmonary vascular haemodynamics.

Essential right heart physiology for the perioperative practitioner POQI IX: current perspectives on the right heart in the perioperative period

As patients continue to live longer from diseases that predispose them to right ventricular (RV) dysfunction or failure, many more patients will require surgery for acute or chronic health issues. Because RV dysfunction results in significant perioperative morbidity if not adequately assessed or managed, understanding appropriate assessment and treatments is important in preventing subsequent morbidity and mortality in the perioperative period. In light of the epidemiology of right heart disease, a working knowledge of right heart anatomy and physiology and an understanding of the implications of right-sided heart function for perioperative care are essential for perioperative practitioners. However, a significant knowledge gap exists concerning this topic. This manuscript is one part of a collection of papers from the PeriOperative Quality Initiative (POQI) IX Conference focusing on "Current Perspectives on the Right Heart in the Perioperative Period." This review aims to provide perioperative clinicians with an essential understanding of right heart physiology by answering five key questions on this topic and providing an explanation of seven fundamental concepts concerning right heart physiology.

Perioperative Characteristics and Outcomes of Fontan Versus Non-Fontan Patients Undergoing Combined Heart-Liver Transplantation: A Retrospective Cohort Study

OBJECTIVES

Combined heart-liver transplantation (CHLT) is becoming increasingly frequent as a maturing population of patients with Fontan-palliated congenital heart disease develop advanced liver fibrosis or cirrhosis. The authors present their experience with CHLT for congenital and noncongenital indications, and identify characteristics associated with poor outcomes that may guide intervention in high-risk patients.

DESIGN

This was a single-center retrospective cohort study.

SETTING

This study was conducted at Vanderbilt University Medical Center in Nashville, Tennessee.

PARTICIPANTS

The study included 16 consecutive adult recipients of CHLT at the authors' institution between April 2017 and February 2022.

INTERVENTIONS

Eleven patients underwent transplantation for Fontan indications, and 5 were transplanted for non-Fontan indications.

MEASUREMENTS AND MAIN RESULTS

Compared with non-Fontan patients, Fontan recipients had longer cardiopulmonary bypass duration (199 v 119 minutes, p =m0.002), operative times (786 v 599 minutes, p = 0.01), and larger blood product transfusions (15.4 v 6.3 L, p = 0.18). Six of 16 patients required extracorporeal membrane oxygenation (ECMO), of whom 4 were Fontan patients who subsequently died. Patients who required ECMO had lower 5-hour lactate clearance (0.0 v 3.5 mmol/L, p = 0.001), higher number of vasoactive infusions, lower pulmonary artery pulsatility indices (0.58 v 1.77, p = 0.03), and higher peak inspiratory pressures (28.0 v 18.5 mmHg, p = 0.01) after liver reperfusion.

CONCLUSIONS

Combined heart-liver transplantation in patients with Fontan-associated end-organ disease is particularly challenging and associated with higher recipient morbidity compared with non-Fontan-related CHLT. Early hemodynamic intervention for signs of ventricular dysfunction may improve outcomes in this growing high-risk population.

Right heart failure after left ventricular assist device implantation: a persistent problem

Left ventricular assist device (LVAD) is an option for bridge-to-transplant or destination therapy for patients with end-stage heart failure. Right heart failure (RHF) remains a complication after LVAD implantation that portends high morbidity and mortality, despite advances in LVAD technology. Definitions of RHF vary, but generally include the need for inotropic or pulmonary vasodilator support, or potential right ventricular (RV) mechanical circulatory support. This review covers the complex pathophysiology of RHF related to underlying myocardial dysfunction, interventricular dependence, and RV afterload, as well as treatment strategies to curtail this challenging problem.

An Update on the Diagnosis and Management of Acute Right Heart Failure

Right ventricular (RV) dysfunction and resultant acute right heart failure (ARHF) is a rapidly growing field of interest, driven by increasing appreciation of its contribution to heart failure morbidity and mortality. Understanding of ARHF pathophysiology has advanced dramatically over recent years and can be broadly described as RV dysfunction related to acute changes in RV afterload, contractility, preload, or left ventricular dysfunction. There are several diagnostic clinical signs and symptoms as well as imaging and hemodynamic assessments that can provide insight into the degree of RV dysfunction. Medical management is tailored to the different causative pathologies, and in cases of severe or end-stage dysfunction, mechanical circulatory support can be utilized. In this review, we describe the pathophysiology of ARHF, how its diagnosis is established by clinical signs and symptoms and imaging findings, and provide an overview of treatment options, both medical and mechanical.

Prediction, prevention, and management of right ventricular failure after left ventricular assist device implantation: A comprehensive review

Left ventricular assist devices (LVADs) are increasingly common across the heart failure population. Right ventricular failure (RVF) is a feared complication that can occur in the early post-operative phase or during the outpatient follow-up. Multiple tools are available to the clinician to carefully estimate the individual risk of developing RVF after LVAD implantation. This review will provide a comprehensive overview of available tools for RVF prognostication, including patient-specific and right ventricle (RV)-specific echocardiographic and hemodynamic parameters, to provide guidance in patient selection during LVAD candidacy. We also offer a multidisciplinary approach to the management of early RVF, including indications and management of right ventricular assist devices in this setting to provide tools that help managing the failing RV.

Right Heart Failure Following Left Ventricular Device Implantation: Natural History, Risk Factors, and Outcomes: An Analysis of the STS INTERMACS Database

BACKGROUND

Our current understanding of right heart failure (RHF) post-left ventricular assist device (LVAD) is lacking. Recently, a new Interagency Registry for Mechanically Assisted Circulatory Support definition of RHF was introduced. Based on this definition, we investigated natural history, risk factors, and outcomes of post-LVAD RHF.

METHODS

Patients implanted with continuous flow LVAD between June 2, 2014, and June 30, 2016 and registered in the Interagency Registry for Mechanically Assisted Circulatory Support/Society of Thoracic Surgeons Database were included. RHF incidence and predictors, and survival after RHF were assessed. The manifestations of RHF which were separately analyzed were elevated central venous pressure, peripheral edema, ascites, and use of inotropes.

RESULTS

Among 5537 LVAD recipients (mean 57±13 years, 49% destination therapy, support 18.9 months) prevalence of 1-month RHF was 24%. Of these, RHF persisted at 12 months in 5.3%. In contrast, de novo RHF, first identified at 3 months, occurred in 5.1% and persisted at 12 months in 17% of these, and at 6 months occurred in 4.8% and persisted at 12 months in 25%. Higher preimplant blood urea nitrogen (ORs,1.03-1.09 per 5 mg/dL increase; P<0.0001), previous tricuspid valve repair/replacement (ORs, 2.01-10.09; P<0.001), severely depressed right ventricular systolic function (ORs,1.17-2.20; P=0.004); and centrifugal versus axial LVAD (ORs,1.15-1.78; P=0.001) represented risk factors for RHC incidence at 3 months. Patients with persistent RHF at 3 months had the lowest 2-year survival (57%) while patients with de novo RHF or RHF which resolved by 3 months had more favorable survival outcomes (75% and 78% at 2 years, respectively; P<0.001).

CONCLUSIONS

RHF at 1 or 3 months post-LVAD was a common and frequently transient condition, which, if resolved, was associated with relatively favorable prognosis. Conversely, de novo, late RHF post-LVAD (>6 months) was more frequently a persistent disorder and associated with increased mortality. The 1-, 3-, and 6-month time points may be used for RHF assessment and risk stratification in LVAD recipients.

Predicting, Recognizing, and Treating Right Heart Failure in Patients Undergoing Durable LVAD Therapy

Despite advancing technology, right heart failure after left ventricular assist device implantation remains a significant source of morbidity and mortality. With the UNOS allocation policy change, a larger proportion of patients proceeding to LVAD are destination therapy and consist of an overall sicker population. Thus, a comprehensive understanding of right heart failure is critical for ensuring the ongoing success of durable LVADs. The purpose of this review is to describe the effect of LVAD implantation on right heart function, review the diagnostic and predictive criteria related to right heart failure, and discuss the current evidence for management and treatment of post-LVAD right heart failure.

Left Ventricular Assist Devices: A Primer for the Non-Mechanical Circulatory Support Provider

Survival after implant of a left ventricular assist device (LVAD) continues to improve for patients with end-stage heart failure. Meanwhile, more patients are implanted with a destination therapy, rather than bridge-to-transplant, indication, meaning the population of patients living long-term on LVADs will continue to grow. Non-LVAD healthcare providers will encounter such patients in their scope of practice, and familiarity and comfort with the physiology and operation of these devices and common problems is essential. This review article describes the history, development, and operation of the modern LVAD. Common LVAD-related complications such as bleeding, infection, stroke, and right heart failure are reviewed and an approach to the patient with an LVAD is suggested. Nominal operating parameters and device response to various physiologic conditions, including hypo- and hypervolemia, hypertension, and device failure, are reviewed.

Outcomes With Phosphodiesterase-5 Inhibitor Use After Left Ventricular Assist Device: An STS-INTERMACS Analysis

BACKGROUND

Elevated right ventricular afterload following continuous-flow left ventricular assist device (CF-LVAD) may contribute to late right heart failure (LRHF). PDE5i (phosphodiesterase-5 inhibitors) are used to treat pulmonary hypertension and right heart dysfunction after CF-LVAD, but their impact on outcomes is uncertain.

METHODS

We queried Interagency Registry for Mechanically Assisted Circulatory Support from 2012 to 2017 for adults receiving a primary CF-LVAD and surviving ≥30 days from index discharge. Patients receiving early PDE5i (ePDE5i) at 1 month were propensity-matched 1:1 with controls. The primary outcome was the cumulative incidence of LRHF, defined using prevailing Interagency Registry for Mechanically Assisted Circulatory Support criteria; secondary outcomes included all-cause mortality and major bleeding.

RESULTS

Among 9627 CF-LVAD recipients analyzed, 2463 (25.6%) received ePDE5i and 1600 were propensity-matched 1:1 with controls. Before implant, ePDE5i patients had more severe RV dysfunction (13.1% versus 9.6%) and higher pulmonary vascular resistance (2.8±2.7 versus 2.2±2.4 WU), both P<0.001, but clinical factors were well-balanced after propensity-matching. In the unmatched cohort, ePDE5i patients had a higher 3-year cumulative incidence of LRHF, mortality, and major bleeding, but these differences were attenuated in the propensity-matched cohort: LRHF 40.8% versus 35.7% (hazard ratio, 1.14 [95% CI, 0.99-1.32]; P=0.07); mortality 38.6% versus 35.8% (hazard ratio, 0.99 [95% CI, 0.86-1.15]; P=0.93); major bleeding 51.2% versus 46.0% (hazard ratio, 1.12 [95% CI, 0.99-1.27]; P=0.06).

CONCLUSIONS

Compared with propensity-matched controls, adult CF-LVAD patients receiving ePDE5i had similar rates of LRHF, mortality, and major bleeding. While intrinsic patient risk factors likely account for more adverse outcomes with ePDE5i in the unmatched cohort, there is no obvious benefit of ePDE5i in the LVAD population.

Degree of change in right ventricular adaptation measures during axillary Impella support informs risk stratification for early, severe right heart failure following durable LVAD implantation

Risk assessment for early, severe right heart failure (RHF) after LVAD implantation remains imperfect. We sought to define the differences in RV adaptation and load after axillary Impella support between patients who experienced RHF and those who did not. Seventeen of 18 patients included were deemed intermediate or high risk for RHF by EUROMACS-RHF score. Before Impella insertion, RV adaptation parameters (RAP, RAP:PCWP, PAPi) were worse in the non-RHF group compared to the RHF group. In both groups, RV load parameters (effective pulmonary arterial elastance, pulmonary vascular resistance, and pulmonary vascular compliance) improved after Impella insertion. Lesser improvements in RV adaptation were seen in the RHF group. Moreover, load-to-adaptation relationships (E_A/RAP and E_A/RAP:PCWP) worsened to a greater degree. In patients at intermediate or high risk for RHF after LVAD, assessment of RV adaptation and load during axillary Impella support may improve risk stratification.

Pulmonary vasodilator use in continuous-flow left ventricular assist device management

Pulmonary hypertension (PH) due to left heart disease is the most common etiology for PH. PH in patients with heart failure with reduced fraction (HFrEF) is associated with reduced functional capacity and increased mortality. PH-HFrEF can be isolated post-capillary or combined pre- and post-capillary PH. Chronic elevation of left-sided filling pressures may lead to reverse remodeling of the pulmonary vasculature with development of precapillary component of PH. Untreated PH in patients with HFrEF results in predominant right heart failure (RHF) with irreversible end-organ dysfunction. Management of PH-HFrEF includes diuretics, vasodilators like angiotensin-converting enzyme inhibitors or angiotensin-receptor blockers or angiotensin-receptor blocker-neprilysin inhibitors, hydralazine and nitrates. There is no role for pulmonary vasodilator use in patients with PH-HFrEF due to increased mortality in clinical trials. In patients with end-stage HFrEF and fixed PH unresponsive to vasodilator challenge, implantation of continuous-flow left ventricular assist device (cfLVAD) results in marked improvement in pulmonary artery pressures within 6 months due to left ventricular (LV) mechanical unloading. The role of pulmonary vasodilators in management of precapillary component of PH after cfLVAD is not well-defined. The purpose of this review is to discuss the pharmacologic management of PH after cfLVAD implantation.

Understanding Longitudinal Changes in Pulmonary Vascular Resistance After Left Ventricular Assist Device Implantation

BACKGROUND

Elevated pulmonary vascular resistance (PVR) is common in patients with advanced heart failure. PVR generally improves after left ventricular assist device (LVAD) implantation, but the rate of decrease has not been quantified and the patient characteristics most strongly associated with this improvement are unknown.

METHODS AND RESULTS

We analyzed 1581 patients from the Interagency Registry for Mechanically Assisted Circulatory Support registry who received a primary continuous-flow LVAD, had a baseline PVR of ≥3 Wood units (WU), and had PVR measured at least once postoperatively. Multivariable linear mixed effects modeling was used to evaluate independent associations between postoperative PVR and patient characteristics. PVR decreased by 1.53 WU (95% confidence interval [CI] 1.27-1.79 WU) per month in the first 3 months postoperatively, and by 0.066 WU (95% CI 0.060-0.070 WU) per month thereafter. Severe mitral regurgitation at any time during follow-up was associated with a 1.29 WU (95% CI 1.05-1.52 WU) higher PVR relative to absence of mitral regurgitation at that time. In a cross-sectional analysis, 15%-25% of patients had persistently elevated PVR of ≥3 WU at any given time within 36 months after LVAD implantation.

CONCLUSION

The PVR tends to decrease rapidly early after implantation, and only more gradually thereafter. Residual mitral regurgitation may be an important contributor to elevated postoperative PVR. Future research is needed to understand the implications of elevated PVR after LVAD implantation and the optimal strategies for prevention and treatment.

Right Ventricular Failure Post-Implantation of Left Ventricular Assist Device: Prevalence, Pathophysiology, and Predictors

Despite advances in left ventricular assist device (LVAD) technology, right ventricular failure (RVF) continues to be a complication after implantation. Most patients undergoing LVAD implantation have underlying right ventricular (RV) dysfunction (either as a result of prolonged LV failure or systemic disorders) that becomes decompensated post-implantation. Additional insults include intra-operative factors or a sudden increase in preload in the setting of increased cardiac output. The current literature estimates post-LVAD RVF from 3.9% to 53% using a diverse set of definitions. A few of the risk factors that have been identified include markers of cardiogenic shock (e.g., dependence on inotropes and Interagency Registry for Mechanically Assisted Circulatory Support profiles) as well as evidence of cardiorenal or cardiohepatic syndromes. Several studies have devised multivariable risk scores; however, their performance has been limited. A new functional assessment of RVF and a novel hepatic marker that describe cholestatic properties of congestive hepatopathy may provide additional predictive value. Furthermore, future studies can help better understand the relationship between pulmonary hypertension and post-LVAD RVF. To achieve our ultimate goal-to prevent and effectively manage RVF post-LVAD-we must start with a better understanding of the risk factors and pathophysiology. Future research on the different etiologies of RVF-ranging from acute post-surgical complication to late-onset RV cardiomyopathy-will help standardize definitions and tailor therapies appropriately.

Noncanonical WNT Activation in Human Right Ventricular Heart Failure

Background: No medical therapies exist to treat right ventricular (RV) remodeling and RV failure (RVF), in large part because molecular pathways that are specifically activated in pathologic human RV remodeling remain poorly defined. Murine models have suggested involvement of Wnt signaling, but this has not been well-defined in human RVF.

Methods: Using a candidate gene approach, we sought to identify genes specifically expressed in human pathologic RV remodeling by assessing the expression of 28 WNT-related genes in the RVs of three groups: explanted nonfailing donors (NF, n = 29), explanted dilated and ischemic cardiomyopathy, obtained at the time of cardiac transplantation, either with preserved RV function (pRV, n = 78) or with RVF (n = 35).

Results: We identified the noncanonical WNT receptor ROR2 as transcriptionally strongly upregulated in RVF compared to pRV and NF (Benjamini-Hochberg adjusted P < 0.05). ROR2 protein expression correlated linearly to mRNA expression (R² = 0.41, P = 8.1 × 10⁻¹⁸) among all RVs, and to higher right atrial to pulmonary capillary wedge ratio in RVF (R² = 0.40, P = 3.0 × 10⁻⁵). Utilizing Masson's trichrome and ROR2 immunohistochemistry, we identified preferential ROR2 protein expression in fibrotic regions by both cardiomyocytes and noncardiomyocytes. We compared RVF with high and low ROR2 expression, and found that high ROR2 expression was associated with increased expression of the WNT5A/ROR2/Ca²⁺ responsive protease calpain-μ, cleavage of its target FLNA, and FLNA phosphorylation, another marker of activation downstream of ROR2. ROR2 protein expression as a continuous variable, correlated strongly to expression of calpain-μ (R² = 0.25), total FLNA (R² = 0.67), calpain cleaved FLNA (R² = 0.32) and FLNA phosphorylation (R² = 0.62, P < 0.05 for all).

Conclusion: We demonstrate robust reactivation of a fetal WNT gene program, specifically its noncanonical arm, in human RVF characterized by activation of ROR2/calpain mediated cytoskeleton protein cleavage.

Left Ventricular Assist Device as Destination Therapy: a State of the Science and Art of Long-Term Mechanical Circulatory Support

PURPOSE OF REVIEW

The purpose of this review is to synthesize and summarize recent developments in the care of patients with end-stage heart failure being managed with a left ventricular assist device (LVAD) as destination therapy.

RECENT FINDINGS

Although the survival of patients treated with LVAD continues to improve, the rates of LVAD-associated complication, such as right ventricular failure, bleeding complications, and major infection, remain high, and management of these patients remains challenging. The durability and hemocompatibility of LVAD support have greatly increased in recent years as a result of new technologies and novel management strategies. Challenges remain in the comprehensive care of patients with destination therapy LVADs, including management of comorbidities and optimizing patient function and quality of life.

Differences in right ventricular-pulmonary vascular coupling and clinical indices between repaired standard tetralogy of Fallot and repaired tetralogy of Fallot with pulmonary atresia

PURPOSE

The purpose of this study was to compare ventricular vascular coupling ratio (VVCR) between patients with repaired standard tetralogy of Fallot (TOF) and those with repaired TOF-pulmonary atresia (TOF-PA) using cardiovascular magnetic resonance (CMR).

MATERIALS AND METHODS

Patients with repaired TOF aged>6 years were prospectively enrolled for same day CMR, echocardiography, and exercise stress test following a standardized protocol. Sanz's method was used to calculate VVCR as right ventricle (RV) end-systolic volume/pulmonary artery stroke volume. Regression analysis was used to examine associations with exercise test parameters, New York Heart Association (NYHA) class, RV size and biventricular systolic function.

RESULTS

A total of 248 subjects were included; of these 222 had repaired TOF (group I, 129 males; mean age, 15.9±4.7 [SD] years [range: 8-29 years]) and 26 had repaired TOF-PA (group II, 14 males; mean age, 17.0±6.3 [SD] years [range: 8-29 years]). Mean VVCR for all subjects was 1.54±0.64 [SD] (range: 0.43-3.80). Mean VVCR was significantly greater in the TOF-PA group (1.81±0.75 [SD]; range: 0.78-3.20) than in the standard TOF group (1.51±0.72 [SD]; range: 0.43-3.80) (P=0.03). VVCR was greater in the 68 NYHA class II subjects (1.79±0.66 [SD]; range: 0.75-3.26) compared to the 179 NYHA class I subjects (1.46±0.61 [SD]; range: 0.43-3.80) (P<0.001).

CONCLUSION

Non-invasive determination of VVCR using CMR is feasible in children and adolescents. VVCR showed association with NYHA class, and was worse in subjects with repaired TOF-PA compared to those with repaired standard TOF. VVCR shows promise as an indicator of pulmonary artery compliance and cardiovascular performance in this cohort.

Right heart failure before LVAD implantation predicts right heart failure after LVAD implantation - is it that easy?

Background

Right heart failure (RHF) after left ventricular assist device (LVAD) implantation is common and associated with worse outcome. Prediction of RHF remains challenging. Our study aims to assess predictors of RHF focusing on clinical manifestations.

Methods

We retrospectively analyzed clinical, echocardiographic and hemodynamic parameters of 112 patients undergoing LVAD implantation. Pre-operative, early (ERHF, day 7 and 14) and late postoperative RHF (LRHF, after 1, 3, 6 and 12 months) were assessed.

Results

In the total study population (87.5% men, mean age 55 years), early RHF was frequent (47% on day 7 and 30% on day 14). Prevalence of late RHF and death from RHF was high after 3, 6 and 12 months (23, 24 and 17%). Pre-existing RHF was only associated with early RHF and persistent, but not for new onset late RHF. Early RHF was associated with lower INTERMACS level (p < 0.001), higher pulmonary vascular resistance (p = 0.046) and CVP/PAWP quotient (p = 0.011), higher bilirubin (p = 0.038) and creatinine (p = 0.013). LRHF was associated with creatinine (p = 0.006), urea (p = 0.012) and load adaption index (p = 0.007). Binary logistic regression models identified no single risk factors. Comparing the predictive value of regression models with a model of three clinical findings (INTERMACS level, age and pre-operative RHF) did not reveal differences in RHF.

Conclusions

RHF before LVAD implantation enhances the risk of early RHF and persistent late RHF, but not for new onset late RHF, supporting the hypothesis of differences in the etiology. Echocardiographic or hemodynamic parameters did not show a predictive value for new onset late RHF. Similar predictive value of clinical findings and statistic models of risk factors suggest that a clinical evaluation is equally matched to predict RHF.

Pulmonary artery pulsatility index: physiological basis and clinical application

Pulmonary artery pulsatility index (PAPi) is a haemodynamic parameter that is derived from right atrial and pulmonary artery pulse pressures. A number of reports have described the prognostic value of PAPi in patients with advanced heart failure and cardiogenic shock. However, the derivation and physiological interpretation of this parameter have received little attention. This review will examine the physiological interpretation and clinical data for PAPi.

Calculation of the ALMA Risk of Right Ventricular Failure After Left Ventricular Assist Device Implantation

Right ventricular failure after continuous-flow left ventricular assist device (LVAD) implantation is still an unsolved issue and remains a life-threatening event for patients. We undertook this study to determine predictors of the patients who are candidates for isolated LVAD therapy as opposed to biventricular support (BVAD). We reviewed demographic, echocardiographic, hemodynamic, and laboratory variables for 258 patients who underwent both isolated LVAD implantation and unplanned BVAD because of early right ventricular failure after LVAD insertion, between 2006 and 2017 (LVAD = 170 and BVAD = 88). The final study patients were randomly divided into derivation (79.8%, n = 206) and validation (20.1%, n = 52) cohorts. Fifty-seven preoperative risk factors were compared between patients who were successfully managed with an LVAD and those who required a BVAD. Nineteen variables demonstrated statistical significance on univariable analysis. Multivariable logistic regression analysis identified destination therapy (odds ratio [OR] 2.0 [1.7-3.9], p = 0.003), a pulmonary artery pulsatility index <2 (OR 3.3 [1.7-6.1], p = 0.001), a right ventricle/left ventricle end-diastolic diameter ratio >0.75 (OR 2.7 [1.5-5.5], p = 0.001), an right ventricle stroke work index <300 mm Hg/ml/m (OR 4.3 [2.5-7.3], p < 0.001), and a United Network for Organ Sharing modified Model for End-Stage Liver Disease Excluding INR score >17 (OR 3.5 [1.9-6.9], p < 0.001) as the major predictors of the need for BVAD. Using these data, we propose a simple risk calculator to determine the suitability of patients for isolated LVAD support in the era of continuous-flow mechanical circulatory support devices.

Pulmonary Arterial Elastance and INTERMACS-Defined Right Heart Failure Following Left Ventricular Assist Device

Background:

Acute right heart failure (RHF) after left ventricular assist device implantation remains a major source of morbidity and mortality, yet the definition of RHF and the preimplant variables that predict RHF remain controversial. This study evaluated the ability of (1) INTERMACS (Interagency Registry for Mechanically Assisted Circulatory Support) RHF classification to predict post-left ventricular assist device survival and (2) preoperative characteristics and hemodynamic parameters to predict severe and severe acute RHF.

Methods and Results:

An international, multicenter study at 4 large academic centers was conducted between 2008 and 2016. All subjects with hemodynamics measured by right heart catheterization within 30 days before left ventricular assist device implantation were included. RHF was defined using the INTERMACS definition for RHF. In total, 375 subjects were included (mean age, 57.4±13.2 years, 54% bridge-to-transplant). Mild RHF was most common (34%), followed by moderate RHF (16%), severe RHF (13%), and severe acute RHF (9%). Estimated on-device survival rates at 2 years were 72%, 71%, and 55% in the patients with none, mild-to-moderate, and severe-to-severe acute RHF, respectively ( P =0.004). In addition, the independent hazard ratio for mortality was only increased in the patients with severe-to-severe acute RHF (hazard ratio, 3.95; 95% CI, 2.16–7.23; P <0.001). INTERMACS-defined RHF was superior to postimplant inotrope duration alone in the prediction of all-cause mortality. In multivariable analysis, older age, lower INTERMACS classes, and higher pulmonary arterial elastance (ratio of systolic pulmonary artery pressure to stroke volume) before left ventricular assist device, were identified as significant predictors of severe-to-severe acute RHF. Stratifying patients by ratio of systolic pulmonary artery pressure to stroke volume and right atrial pressure significantly improved the discrimination between patients at risk for severe-to-severe acute RHF.

Conclusions:

The INTERMACS RHF classification correctly identifies patients at risk for mortality, though this risk is only increased in patients with severe-to-severe acute RHF. Several predictors for RHF were identified, of which ratio of systolic pulmonary artery pressure to stroke volume was the strongest hemodynamic predictor. Coupling ratio of systolic pulmonary artery pressure to stroke volume with right atrial pressure may be most helpful in identifying patients at risk for severe-to-severe acute RHF.

Preimplant Phosphodiesterase-5 Inhibitor Use Is Associated With Higher Rates of Severe Early Right Heart Failure After Left Ventricular Assist Device Implantation

Background Early right heart failure (RHF) occurs commonly in left ventricular assist device (LVAD) recipients, and increased right ventricular (RV) afterload may contribute. Selective pulmonary vasodilators, like phosphodiesterase-5 inhibitors (PDE5i), are used off-label to reduce RV afterload before LVAD implantation, but the association between preoperative PDE5i use and early RHF after LVAD is unknown. Methods and Results We analyzed adult patients from the INTERMACS registry (Interagency Registry for Mechanically Assisted Circulatory Support) who received a continuous flow LVAD after 2012. Patients on PDE5i were propensity-matched 1:1 to controls. The primary outcome was the incidence of severe early RHF, defined as the composite of death from RHF within 30 days, need for RV assist device support within 30 days, or use of inotropes beyond 14 days. Of 11 544 continuous flow LVAD recipients, 1199 (10.4%) received preoperative PDE5i. Compared to controls, patients on PDE5i had higher pulmonary artery systolic pressure (53.4 mm Hg versus 49.5 mm Hg) and pulmonary vascular resistance (2.6 WU versus 2.3 WU; P<0.001 for both). Before propensity matching, the incidence of severe early RHF was higher among patients on PDE5i than in controls (29.4% versus 23.1%; unadjusted odds ratio (OR), 1.32; 95% CI, 1.17-1.50). This association persisted after propensity matching (PDE5i, 28.9% versus control 23.7%; OR, 1.31; 95% CI, 1.09-1.57), driven by a higher incidence of prolonged inotropic support. Similar results were observed across a wide range of subgroups stratified by markers of pulmonary vascular disease and RV dysfunction. Conclusions Patients treated with preoperative PDE5i had markers of increased RV afterload and HF severity compared to unmatched controls. Even after propensity matching, patients receiving preimplant PDE5i therapy had higher rates of post-LVAD RHF.

Right ventricular outflow tract velocity time integral-to-pulmonary artery systolic pressure ratio: a non-invasive metric of pulmonary arterial compliance differs across the spectrum of pulmonary hypertension

Pulmonary arterial compliance (PAC), invasively assessed by the ratio of stroke volume to pulmonary arterial (PA) pulse pressure, is a sensitive marker of right ventricular (RV)-PA coupling that differs across the spectrum of pulmonary hypertension (PH) and is predictive of outcomes. We assessed whether the echocardiographically derived ratio of RV outflow tract velocity time integral to PA systolic pressure (RVOT-VTI/PASP) (a) correlates with invasive PAC, (b) discriminates heart failure with preserved ejection-associated PH (HFpEF-PH) from pulmonary arterial hypertension (PAH), and (c) is associated with functional capacity. We performed a retrospective cohort study of patients with PAH (n = 70) and HFpEF-PH (n = 86), which was further dichotomized by diastolic pressure gradient (DPG) into isolated post-capillary PH (DPG < 7 mmHg; Ipc-PH, n = 54), and combined post- and pre-capillary PH (DPG ≥ 7 mm Hg; Cpc-PH, n = 32). Of the 156 patients, 146 had measurable RVOT-VTI or PASP and were included in further analysis. RVOT-VTI/PASP correlated with invasive PAC overall (ρ = 0.61, P < 0.001) and for the PAH (ρ = 0.38, P = 0.002) and HFpEF-PH (ρ = 0.63, P < 0.001) groups individually. RVOT-VTI/PASP differed significantly across the PH spectrum (PAH: 0.13 [0.010–0.25] vs. Cpc-PH: 0.20 [0.12–0.25] vs. Ipc-PH: 0.35 [0.22–0.44]; P < 0.001), distinguished HFpEF-PH from PAH (AUC = 0.72, 95% CI = 0.63–0.81) and Cpc-PH from Ipc-PH (AUC = 0.78, 95% CI = 0.68–0.88), and remained independently predictive of 6-min walk distance after multivariate analysis (standardized β-coefficient = 27.7, 95% CI = 9.2–46.3; P = 0.004). Echocardiographic RVOT-VTI/PASP is a novel non-invasive metric of PAC that differs across the spectrum of PH. It distinguishes the degree of pre-capillary disease within HFpEF-PH and is predictive of functional capacity.

Intersection of Pulmonary Hypertension and Right Ventricular Dysfunction in Patients on Left Ventricular Assist Device Support: Is There a Role for Pulmonary Vasodilators?

Left ventricular assist devices (LVADs) improve survival and quality of life in patients with advanced heart failure. Despite these benefits, combined post- and precapillary pulmonary hypertension can be particularly problematic in patients on LVAD support, often exacerbating right ventricular (RV) dysfunction. Both persistently elevated pulmonary vascular resistance and RV dysfunction are associated with adverse outcomes, including death after LVAD. These observations have led to significant interest in the use of pulmonary vasodilators to treat pulmonary hypertension and preserve RV function among LVAD-supported patients. Although pulmonary vasodilators are commonly used for the treatment of pulmonary hypertension and RV dysfunction in LVADs, the benefits of this practice remain unclear. The purpose of this review is to highlight the current challenges in managing pulmonary vascular disease and RV dysfunction in patients with heart failure on LVAD support.

Temporary assist device support for the right ventricle: pre-implant and post-implant challenges

Severe right ventricular (RV) failure is more likely reversible than similar magnitudes of left ventricular (LV) failure and, because reversal of both adaptive remodeling and impaired contractility require most often only short periods of support, the use of temporary RV assist devices (t-RVADs) can be a life-saving therapy option for many patients. Although increased experience with t-RVADs and progresses made in the development of safer devices with lower risk for complications has improved both recovery rate of RV function and patient survival, the mortality of t-RVAD recipients can still be high but it depends mainly on the primary cause of RV failure (RVF), the severity of end-organ dysfunction, and the timing of RVAD implantation, and much less on adverse events and complications related to RVAD implantation, support, or removal. Reduced survival of RVAD recipients should therefore not discourage appropriate application of RVADs because their underuse further reduces the chances for RV recovery and patient survival. The article reviews and discusses the challenges related to the pre-implant and post-implant decision-making processes aiming to get best possible therapeutic results. Special attention is focused on pre-implant RV assessment and prediction of RV improvement during mechanical unloading, patient selection for t-RVAD therapy, assessment of unloading-promoted RV recovery, and prediction of its stability after RVAD removal. Particular consideration is also given to prediction of RVF after LVAD implantation which is usually hampered by the complex interactions between the different risk factors related indirectly or directly to the RV potential for reverse remodeling and functional recovery.

Performance of Noninvasive Assessment in the Diagnosis of Right Heart Failure After Left Ventricular Assist Device

Right heart failure (RHF) after left ventricular assist device (LVAD) is associated with poor outcomes. Interagency Registry for Mechanically Assisted Circulatory Support (Intermacs) defines RHF as elevated right atrial pressure (RAP) plus venous congestion. The purpose of this study was to examine the diagnostic performance of the noninvasive Intermacs criteria using RAP as the gold standard. We analyzed 108 patients with LVAD who underwent 341 right heart catheterizations (RHC) between January 1, 2006, and December 31, 2013. Physical exam, echocardiography, and laboratory data at the time of RHC were collected. Conventional two-by-two tables were used and missing data were excluded. The noninvasive Intermacs definition of RHF is 32% sensitive (95% cardiac index (CI), 0.21-0.44) and 97% specific (95% CI, 0.95-0.99) for identifying elevated RAP. Clinical assessment failed to identify two-thirds of LVAD patients with RAP > 16 mm Hg. More than half of patients with elevated RAP did not have venous congestion, which may represent a physiologic opportunity to mitigate the progression of disease before end-organ damage occurs. One-quarter of patients who met the noninvasive definition of RHF did not actually have elevated RAP, potentially exposing patients to unnecessary therapies. In practice, if any component of the Intermacs definition is present or equivocal, our data suggest RHC is warranted to establish the diagnosis.

Cardiac passive-aggressive behavior? The right ventricle in patients with a left ventricular assist device

INTRODUCTION

Right ventricular failure (RVF) affects up to 50% of patients post-left ventricular assist device (LVAD) implantation, and carries significant morbidity and mortality. There is no widely-used long-term mechanical support option for the right ventricle, thus early identification, prevention and medical treatment of RVF is of the upmost importance. Areas covered: A PubMed search was first completed searching 'Right ventricular failure post-LVAD' which yielded 152 results, and a subsequent search was performed under 'RV mechanical support' which yielded 374 results, and was filtered to 'humans' and literature written in English, generating 219 results. We focused this research on pre-operative risk factors identified in the literature for developing RVF-post LVAD implantation, and the medical and surgical treatment options for RVF, including mechanical treatment options. Expert commentary: There is little consensus on pre-operative risk factors that reliably predict RVF post-LVAD implantation. Large prospective randomized trials would help clarify indications for specific medical and surgical therapy. We gather this knowledge in the present article and describe the main RVF remediation modalities. Surgeons and anesthesiologists should help prevent and have a low threshold for initiating supportive treatment for RVF, which may include increasingly invasive therapies up to long-term mechanical RV support.