Heart-lung interactions in COVID-19: prognostic impact and usefulness of bedside echocardiography for monitoring of the right ventricle involvement

Abstract

Due to the SARS-CoV-2 infection-related severe pulmonary tissue damages associated with a relative specific widespread thrombotic microangiopathy, the pathophysiologic role of heart-lung interactions becomes crucial for the development and progression of right ventricular (RV) dysfunction. The high resistance in the pulmonary circulation, as a result of small vessel thrombosis and hypoxemia, is the major cause of right heart failure associated with a particularly high mortality in severe COVID-19. Timely identification of patients at high risk for RV failure, optimization of mechanical ventilation to limit its adverse effects on RV preload and afterload, avoidance of medication-related increase in the pulmonary vascular resistance, and the use of extracorporeal membrane oxygenation in refractory respiratory failure with hemodynamic instability, before RV failure develops, can improve patient survival. Since it was confirmed that the right-sided heart is particularly involved in the clinical deterioration of patients with COVID-19 and pressure overload-induced RV dysfunction plays a key role for patient outcome, transthoracic echocardiography (TTE) received increasing attention. Limited TTE focused on the right heart appears highly useful in hospitalized COVID-19 patients and particularly beneficial for monitoring of critically ill patients. In addition to detection of right-sided heart dilation and RV dysfunction, it enables assessment of RV-pulmonary arterial coupling and evaluation of RV adaptability to pressure loading which facilitate useful prognostic statements to be made. The increased use of bedside TTE focused on the right heart could facilitate more personalized management and treatment of hospitalized patients and can contribute towards reducing the high mortality associated with SARS-CoV-2 infection.

Keywords: COVID-19; Echocardiography; Heart failure; Heart–lung interaction; Pulmonary vessel thrombosis; Right ventricle.

Fig. 1

Pathophysiologic role of heart–lung interactions for the development and progression of life-threatening RV dysfunction during SARS-COV-2 infection. The bold red arrows indicate the major direct impact of the virus on the lung tissue. The red dotted arrows indicate other possible direct cardiovascular damages of the virus with prognostic relevance

Fig. 2

Calculation of the right ventricular load adaptation index (LAI_RV). a Measurement of the right ventricular (RV) end-diastolic area (A_ED) and long axis lengths in the apical 4 chamber view. b and c Measurement of the tricuspid regurgitation velocity–time integral (VTI_TR) using the continuous wave Doppler. The LAI_RV value of 17.0 is reduced and indicates that in this patient with pulmonary arterial hypertension (pulmonary arterial systolic and mean pressure: 48 mmHg and 37 mmHg, respectively), the RV dilation is more pronounced than one would expect on the basis of its present afterload. The limited adaptation possibilities to the increased afterload are exceeded, and a reduction of pulmonary vascular resistance is highly needed in order to prevent further aggravation of RV dysfunction

Fig. 3

Major signs of either right ventricular improvement or further deterioration revealed by echocardiographic monitoring of patients with increased resistance in the pulmonary circulation. RV right ventricle, TR tricuspid valve regurgitation, SV stroke volume, CO cardiac output, LAI_RV right ventricular load adaptation index, TAPSE tricuspid annulus peak systolic excursion, FAC_RV RV fractional area change, RVLS right ventricular longitudinal strain