Right ventricle-pulmonary artery uncoupling in critically ill decompensated chronic liver disease patients: an exploratory observational study

Point of care Echocardiography has been a part of modern-day ICU training and an integral part of patient management. Use of point of care ultrasound (POCUS) in decision making and management of critical cases is increasing day by day.

Right ventricular–pulmonary artery coupling (RV-PA coupling) refers to the relationship between RV contractility and RV afterload. Normal RV-PA coupling is maintained only when RV function and pulmonary vascular resistance are appropriately matched. RV-PA uncoupling occurs when RV contractility cannot increase to match RV afterload, resulting in RV dysfunction. Therefore, early and accurate evaluation of RV-PA coupling is of great significance for a patient’s condition assessment. Right ventricle (RV)-pulmonary artery (PA) uncoupling has been studied in patient with sepsis.[1,2,3].

Hemodynamics in critically ill liver disease patients resembles  sepsis and septic shock in the sense of  increased permeability of vessels, hyper-dynamic circulation, and decreased effective blood volume. Patients can develop RV dysfunction as a consequence of left ventricular (LV) dysfunction; however, cirrhotic cardiomyopathy, direct RV myocardial injury and increased RV afterload from increased pulmonary vascular resistance (PVR) are also important contributory factors. Chronic liver disease itself can cause ventricular dysfunction and pulmonary artery (PA) hypertension which can lead to RV- PA uncoupling.

RV performance is frequently assessed in isolation yet it is closely related to afterload; combined evaluation of the pulmonary circulation may be more beneficial at the bedside. The ratio of tricuspid annular plane systolic excursion (TAPSE) and PA systolic pressure (PASP) is deemed as an indicator of right ventricular pulmonary arterial coupling, the normal value being > 0.3.[4]

TAPSE is a simple and reproducible parameter of RV systolic function with low inter-observer variability, even in patients with raised right-sided pressures.[5,6] PASP can be reliably determined from the peak tricuspid regurgitation velocity in the majority of patients[7]. The TAPSE/PASP ratio was found to be associated with mortality in patients with pulmonary arterial hypertension and heart failure. [8,9]. A retrospective exploratory study   was conducted by Bowcock et al [3] on 131 patients on RVOT Doppler flow analysis and pulmonary artery coupling in sepsis. It was observed that increased PVR and RV-PA uncoupling (TAPSE/ PASP ratio < 0.31mm/mm Hg) were present in a significant portion of patient with sepsis.

Another prospective study was performed on 118 mechanically ventilated patient with septic shock by Zhang et al.[2] TAPSE/ PASP ratio demonstrated prognostic value for  ICU mortality , duration of mechanical ventilation.

References:

1. Winkelhorst JC, et al: Right ventricular function and long term outcome in sepsis; a retrospective cohort study. Shock.2019.

2. Zhang et al. Prognostic implication o tricuspid annular plane systolic excursion/ pulmonary arterial systolic pressure ratio in septic shock patients. Cardiovascular ultrasound.2020.

3. Bowcock et al, Right ventricular outflow tract Doppler flow analysis and pulmonary arterial coupling by transthoracic echocardiography in sepsis: a retrospective exploratory study. Critical care. 2022

4. Kubba S et al, Methods for evaluating right ventricular function and ventricular arterial coupling. Progress in cardiovascular disease.2016.

5. Kaul et al. Assessment of right ventricular function using two dimensional echocardiography. Am Heart J. 1984

6.Hammarstrom E et al, Tricuspid Annular motion. J Am Soc echocardiography. 1991

7.Rudski L G et al, Guidelines for the echocardiographic assessment of right heart in adult. . J Am Soc echocardiography. 2010

8.Guazzi M et al, RV contractile function and its coupling to pulmonary circulation in heart failure with preserved ejection fraction: stratification of clinical phenotype and outcome. JACC cardiovasc imaging. 2017

9. Tello K et al, Relevance of the TAPSE/ PASP ratio in pulmonary arterial hypertension. Int J Cardiol. 2018