RESEARCH ARTICLE • Right Ventricle Early Inflow-Outflow Index May Inform About the Severity of Pneumonia in Patients with COVID-19

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RESEARCH ARTICLE • Right Ventricle Early Inflow-Outflow Index May Inform About the Severity of Pneumonia in Patients with COVID-19

Source: J Clin Ultrasound. 2021;1–7


Although COVID-19 infection was initially thought to be a disease presenting with viral pneumonia, it may also affect multiple organ systems. The cardiovascular system is one of the most frequently affected systems, and there is an increasing prevalence of cardiovascular complications, including new or worsening heart failure, arrhythmia, acute myocarditis, and myocardial infarction, particularly in severely and critically ill patients.

The cardiovascular system can be affected by COVID-19 due to the direct damage to cardiomyocytes, or it may be affected due to the heart-lung interaction. Right cardiac functions may be affected because of various pathophysiological mechanisms such as lung parenchymal damage, altered pulmonary hemodynamics, pulmonary vasoconstriction secondary to hypoxia, and thrombotic process.

Recently, the RV early inflow-outflow (RVEIO) index has been identified as a possible and indirect marker of the severity of tricuspid regurgitation and RV dysfunction in pulmonary embolism.

The aimed of this study was to investigate the relationship between the severity of COVID-19 pneumonia and the newly defined RVEIO index as an indirect indicator of RV dysfunction based on the heart-lung interaction.


Study Design and Patients

54 patients diagnosed with COVID-19 pneumonia were prospectively enrolled in this study. Patients having pneumonia from COVID- 19 diagnosed with chest computed tomography (CT) imaging were examined. Patients with known pulmonary hypertension, chronic lung pathologies, previous or current pulmonary embolism, severe renal failure, severe valvular disease, heart failure, atrial fibrillation, or poor echocardiographic images were excluded from the study.

Three categories of severity of pneumonia were described as mild, moderate, and severe according to the CT findings based on previous research.


Echocardiographic assessment was performed at the time of intensive care unit admission by the same echocardiographer who was blinded to the study design and patients’ clinical data. It  was performed before mechanical ventilation initiation in order to avoid impairment of the right ventricular filling hemodynamics and affecting the right ventricular parameters by mechanical ventilation.

Conventional two-dimensional and Doppler echocardiographic examinations were performed according to the recommendations of the American Society of Echocardiography. In addition to LV parameters, the following parameters were used to evaluate RV function:

  1. Tricuspid lateral annular systolic velocity (Sm, sometimes referred to as S’).
  2. Pulmonary artery systolic pressure.
  3. Right atrial pressure was assessed based on the size and collapsibility of the inferior vena cava.
  4. Tricuspid inflow: Peak transtricuspid early diastolic wave (E wave) velocity and active filling with atrial systolic (A wave) velocity were measured, and E/A was calculated.
  5. Pulmonary artery acceleration time.
  6. RV outflow velocity time interval (VTI).
  7. RVEIO index was obtained using the following equation: RVEIO index = Early trans-tricuspid filling wave velocity (E-wave velocity [cm/s] ∕ RVOT VTI).


54 patients were included in the study and were divided into two groups according to chest CT – 26 patients with severe pneumonia and 28 with mild pneumonia.

Compared to patients with mild pneumonia, patients with severe pneumonia had:

  1. Lower values of:
    1. Deceleration time (200.8 ± 44.9 vs. 172.1 ± 44)
    2. TAPSE (2.2 ± 0.4 vs. 1.9 ± 0.3)
    3. Pulmonary artery acceleration time (110.1 ± 20.6 vs. 80.4 ± 19.5)
    4. RVOT VTI (16.3 ± 4.2 vs. 14.1 ± 2.3)
  2. Higher values of:
    1. Tricuspid E (53 ± 14 vs. 780 ± 23)
    2. RVEIO index (3.5 ± 1.3 vs. 5.7 ± 1.6)

RVEIO index >4.2 predicted the severe pneumonia with 77% sensitivity and 79% specificity. independent predictive parameters for severe pneumonia included O2 saturation, D-dimer, Sm and RVEIO index.


The authors concluded that RVEIO index can be used as a bedside, noninvasive, easily accessible, and useful marker to identify the COVID-19 patient group with widespread pneumonia. This, in turn, may help identify patients with high risk of complications, morbidity, and mortality.