The difficulty in defining right ventricular failure at the bedside and its clinical significance

Right Ventricular Dysfunction on Transthoracic Echocardiography and Long-Term Mortality in the Critically Unwell: A Systematic Review and Meta-Analysis

OBJECTIVE

Right ventricular dysfunction (RVD) is common in the critically ill. To date studies exploring RVD sequelae have had heterogenous definitions and diagnostic methods, with limited follow-up. Additionally much literature has been pathology specific, limiting applicability to the general critically unwell patient.

METHOD AND STUDY DESIGN

We conducted a systematic review and meta-analysis to evaluate the impact of RVD diagnosed with transthoracic echocardiography (TTE) on long-term mortality in unselected critically unwell patients compared to those without RVD. A systematic search of EMBASE, Medline and Cochrane was performed from inception to March 2022. All RVD definitions using TTE were included. Patients were those admitted to a critical or intensive care unit, irrespective of disease processes. Long-term mortality was defined as all-cause mortality occurring at least 30 days after hospital admission. A priori subgroup analyses included disease specific and delayed mortality (death after hospital discharge/after the 30th day from hospital admission) in patients with RVD. A random effects model analysis was performed with the Dersimionian and Laird inverse variance method to generate effect estimates.

RESULTS

Of 5985 studies, 123 underwent full text review with 16 included (n = 3196). 1258 patients had RVD. 19 unique RVD criteria were identified. The odds ratio (OR) for long term mortality with RVD was 2.92 (95% CI 1.92-4.54, I2 76.4%) compared to no RVD. The direction and extent was similar for cardiac and COVID19 subgroups. Isolated RVD showed an increased risk of delayed mortality when compared to isolated left/biventricular dysfunction (OR 2.01, 95% CI 1.05-3.86, I2 46.8%).

CONCLUSION

RVD, irrespective of cause, is associated with increased long term mortality in the critically ill. Future studies should be aimed at understanding the pathophysiological mechanisms by which this occurs. Commonly used echocardiographic definitions of RVD show significant heterogeneity across studies, which contributes to uncertainty within this dataset.

The value of right ventricular to pulmonary arterial coupling in the critically ill: a National Echocardiography Database of Australia (NEDA) substudy

BACKGROUND

Right ventricular (RV) function is tightly coupled to afterload, yet echocardiographic indices of RV function are frequently assessed in isolation. Normalizing RV function for afterload (RV-PA coupling) using a simplified ratio of tricuspid annular plane systolic excursion (TAPSE)/ tricuspid regurgitant velocity (TRV) could help to identify RV decompensation and improve risk stratification in critically ill patients. This is the first study to explore the distribution of TAPSE/TRV ratio and its prognostic relevance in a large general critical care cohort.

METHODS

We undertook retrospective analysis of echocardiographic, clinical, and mortality data of intensive care unit (ICU) patients between January 2012 and May 2017. A total of 1077 patients were included and stratified into tertile groups based on TAPSE/TRV ratio: low (< 5.9 mm.(m/s)-1), middle (≥ 5.9-8.02 mm.(m/s)-1), and high (≥ 8.03 mm.(m/s)-1). The distribution of the TAPSE/TRV ratio across ventricular function subtypes of normal, isolated left ventricular (LV), isolated RV, and biventricular dysfunction was explored. The overall prognostic relevance of the TAPSE/TRV ratio was tested, including distribution across septic, cardiovascular, respiratory, and neurological subgroups.

RESULTS

Higher proportions of ventricular dysfunctions were seen in low TAPSE/TRV tertiles. TAPSE/TRV ratio is impacted by LV systolic function but to a lesser extent than RV dysfunction or biventricular dysfunction. There was a strong inverse relationship between TAPSE/TRV ratio and survival. After multivariate analysis, higher TAPSE/TRV ratios (indicating better RV-PA coupling) were independently associated with lower risk of death in ICU (HR 0.927 [0.872-0.985], p < 0.05). Kaplan-Meier analysis demonstrated higher overall survival in middle and high tertiles compared to low tertiles (log rank p < 0.0001). The prognostic relevance of TAPSE/TRV ratio was strongest in respiratory and sepsis subgroups. Patients with TAPSE/TRV < 5.9 mm (m/s)-1 had a significantly worse prognosis than those with higher TAPSE/TRV ratios.

CONCLUSION

The TAPSE/TRV ratio has prognostic relevance in critically ill patients. The prognostic power may be stronger in respiratory and septic subgroups. Larger prospective studies are needed to investigate the role of TAPSE/TRV in pre-specified subgroups including its role in clinical decision-making.

Echocardiography phenotypes of right ventricular involvement in COVID-19 ARDS patients and ICU mortality: post-hoc (exploratory) analysis of repeated data from the ECHO-COVID study

PURPOSE

Exploratory study to evaluate the association of different phenotypes of right ventricular (RV) involvement and mortality in the intensive care unit (ICU) in patients with acute respiratory distress syndrome (ARDS) due to coronavirus disease 2019 (COVID-19).

METHODS

Post-hoc analysis of longitudinal data from the multicenter ECHO-COVID observational study in ICU patients who underwent at least two echocardiography examinations. Echocardiography phenotypes were acute cor pulmonale (ACP, RV cavity dilatation with paradoxical septal motion), RV failure (RVF, RV cavity dilatation and systemic venous congestion), and RV dysfunction (tricuspid annular plane systolic excursion ≤ 16 mm). Accelerated failure time model and multistate model were used for analysis.

RESULTS

Of 281 patients who underwent 948 echocardiography studies during ICU stay, 189 (67%) were found to have at least 1 type of RV involvements during one or several examinations: ACP (105/281, 37.4%), RVF (140/256, 54.7%) and/or RV dysfunction (74/255, 29%). Patients with all examinations displaying ACP had survival time shortened by 0.479 [0.284-0.803] times when compared to patients with all examinations depicting no ACP (P = 0.005). RVF showed a trend towards shortened survival time by a factor of 0.642 [0.405-1.018] (P = 0.059), whereas the impact of RV dysfunction on survival time was inconclusive (P = 0.451). Multistate analysis showed that patients might transit in and out of RV involvement, and those who exhibited ACP in their last critical care echocardiography (CCE) examination had the highest risk of mortality (hazard ratio (HR) 3.25 [2.38-4.45], P < 0.001).

CONCLUSION

RV involvement is prevalent in patients ventilated for COVID-19 ARDS. Different phenotypes of RV involvement might lead to different ICU mortality, with ACP having the worst outcome.

Cardiovascular Subphenotypes in ARDS: Diagnostic and Therapeutic Implications and Overlap with Other ARDS Subphenotypes

Acute respiratory distress syndrome (ARDS) is a highly heterogeneous clinical condition. Shock is a poor prognostic sign in ARDS, and heterogeneity in its pathophysiology may be a barrier to its effective treatment. Although right ventricular dysfunction is commonly implicated, there is no consensus definition for its diagnosis, and left ventricular function is neglected. There is a need to identify the homogenous subgroups within ARDS, that have a similar pathobiology, which can then be treated with targeted therapies. Haemodynamic clustering analyses in patients with ARDS have identified two subphenotypes of increasingly severe right ventricular injury, and a further subphenotype of hyperdynamic left ventricular function. In this review, we discuss how phenotyping the cardiovascular system in ARDS may align with haemodynamic pathophysiology, can aid in optimally defining right ventricular dysfunction and can identify tailored therapeutic targets for shock in ARDS. Additionally, clustering analyses of inflammatory, clinical and radiographic data describe other subphenotypes in ARDS. We detail the potential overlap between these and the cardiovascular phenotypes.

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.

Right ventricular strain measurements in critically ill patients: an observational SICS sub-study

BACKGROUND

Right ventricular (RV) dysfunction is common in critically ill patients and is associated with poor outcomes. RV function is usually evaluated by Tricuspid Annular Plane Systolic Excursion (TAPSE) which can be obtained using critical care echocardiography (CCE). Myocardial deformation imaging, measuring strain, is suitable for advanced RV function assessment and has widely been studied in cardiology. However, it is relatively new for the Intensive Care Unit (ICU) and little is known about RV strain in critically ill patients. Therefore, the objectives of this study were to evaluate the feasibility of RV strain in critically ill patients using tissue-Doppler imaging (TDI) and explore the association between RV strain and conventional CCE measurements representing RV function.

METHODS

This is a single-center sub-study of two prospective observational cohorts (Simple Intensive Care Studies (SICS)-I and SICS-II). All acutely admitted adults with an expected ICU stay over 24 h were included. CCE was performed within 24 h of ICU admission. In patients in which CCE was performed, TAPSE, peak systolic velocity at the tricuspid annulus (RV s') and TDI images were obtained. RV free wall longitudinal strain (RVFWSL) and RV global four-chamber longitudinal strain (RV4CSL) were measured during offline analysis.

RESULTS

A total of 171 patients were included. Feasibility of RVFWSL and RV4CSL was, respectively, 62% and 56% in our population; however, when measurements were performed, intra- and inter-rater reliability based on the intraclass correlation coefficient were good to excellent. RV dysfunction based on TAPSE or RV s' was found in 56 patients (33%) and 24 patients (14%) had RV dysfunction based on RVFWSL or RV4CSL. In 14 patients (8%), RVFWSL, RV4CSL, or both were reduced, despite conventional RV function measurements being preserved. These patients had significantly higher severity of illness scores. Sensitivity analysis with fractional area change showed similar results.

CONCLUSIONS

TDI RV strain imaging in critically ill patients is challenging; however, good-to-excellent reproducibility was shown when measurements were adequately obtained. Future studies are needed to elucidate the diagnostic and prognostic value of RV strain in critically ill patients, especially to outweigh the difficulty and effort of imaging against the clinical value.

Right ventricular outflow tract Doppler flow analysis and pulmonary arterial coupling by transthoracic echocardiography in sepsis: a retrospective exploratory study

INTRODUCTION

Right ventricular (RV) and pulmonary vascular dysfunction appear to be common in sepsis. RV performance is frequently assessed in isolation, yet its close relationship to afterload means combined analysis with right ventricular outflow tract (RVOT) Doppler and RV-pulmonary arterial (RV-PA) coupling may be more informative than standard assessment techniques. Data on feasibility and utility of these parameters in sepsis are lacking and were explored in this study.

METHODS

This is a retrospective study over a 3-year period of one-hundred and thirty-one patients admitted to ICU with sepsis who underwent transthoracic echocardiography (TTE) with RVOT pulsed wave Doppler. RVOT Doppler flow and RV-PA coupling was evaluated alongside standard measurements of RV systolic function and pulmonary pressures. RVOT Doppler analysis included assessment of pulmonary artery acceleration time (PAAT), velocity time integral and presence of notching. RV-PA coupling was assessed using tricuspid annular planar systolic excursion/pulmonary artery systolic pressure (TAPSE/PASP) ratio.

RESULTS

PAAT was measurable in 106 (81%) patients, and TAPSE/PASP was measurable in 77 (73%). Seventy-three (69%) patients had a PAAT of ≤ 100 ms suggesting raised pulmonary vascular resistance (PVR) is common. RVOT flow notching occurred in 15 (14%) of patients. TRV was unable to be assessed in 24 (23%) patients where measurement of PAAT was possible. RV dysfunction (RVD) was present in 28 (26%), 26 (25%) and 36 (34%) patients if subjective assessment, TAPSE < 17 mm and RV dilatation definitions were used, respectively. There was a trend towards shorter PAAT with increasing severity of RVD. RV-PA uncoupling defined as a TAPSE/PASP < 0.31 mm/mmHg was present in 15 (19%) patients. As RV dilatation increased the RV-PA coupling ratio decreased independent of LV systolic function, whereas TAPSE appeared to be more susceptible to changes in LV systolic function.

CONCLUSION

Raised PVR and RV-PA uncoupling is seen in a significant proportion of patients with sepsis. Non-invasive assessment with TTE is feasible. The role of these parameters in assisting improved definitions of RVD, as well as their therapeutic and prognostic utility against standard parameters, deserves further investigation.