New application of saline contrast-enhanced electrical impedance tomography method for right ventriculography besides lung perfusion: detection of right-to-left intracardiac shunt

Abstract

Aim Saline contrast-enhanced electrical impedance tomography (EIT) has been used to identify the respiratory failure etiologies through assessment of regional lung perfusion at the bedside. In this study, we introduce a novel approach to detect right-to-left intracardiac shunt based on the center of heart (CoH) parameter determined from the early phase of impedance-time curve after saline bolus injection. Methods and result The timepoints when the saline bolus enters the heart (T0) and the lung regions (T1) are identified at first. A moving time window from T0 to T1 is then generated with steps of 0.5 s and the slope of the impedance-time curve in each pixel within the window calculated. CoH is calculated as the geometric center of pixel slope values in the right-to-left image direction. To illustrate how this method works in practice, we calculated the CoH values at T0 to T1 in 10 control hypoxic patients with no right-to-left shunt. In addition, we examined two critically ill patients with right-to-left intracardiac shunt. one was postcardiac surgery patient who had a residual atrial septal defect by color doppler of transesophageal echocardiograph. The other patient had a congenital heart disease of ventricular septal defect by color doppler of trans-thoracic echocardiography. A large difference in CoH between T0 to T1 was observed in the two patients with intracardiac shunt than in the control patients (11.06 ± 3.17% vs. 1.99 ± 1.43%, P = 0.030). Conclusion saline bolus EIT for lung perfusion might be used as ventriculography to identify the right-to-left intracardiac shunt at the bedside.

Real-time non-invasive monitoring of pulmonary embolism based on dynamic EIT technology: a new method

“…NaCl solution) in the respiratory depression state enhance impedance changes in the perfused area and perform EIT imaging [12,13]. The results of the comparative study showed a good correlation between the results obtained by this method and PET and SPECT in the detection of pulmonary perfusion function [14], as well as a superiority in the ability to identify acute pulmonary embolism [15], which led to the initial clinical acceptance of the method. However, this method not only has the shortcomings of being invasive and inconvenient to operate, but also fails to achieve continuous monitoring of pulmonary perfusion, and thus cannot be used for the monitoring and warning of pulmonary embolism.…”