Basics of Functional Echocardiography in Children and Neonates

Abstract

Functional echocardiography has become an invaluable tool in the pediatric and neonatal intensive care unit. "Point-of-care," "target," or "focus" echocardiography allows bedside cardiac ultrasound evaluation of the hemodynamic status of the patient, helps in directing treatment, thus improves patients care. In order to be able to perform functional echocardiography, it is essential to understand the principles of ultrasound, to know the echocardiographic equipment and settings necessary to acquire the images. This article focuses therefore on the basics of cardiac ultrasound. It is meant to give an overview of two-dimensional echocardiographic views, M-mode imaging and Doppler echocardiography for neonatologists and pediatric intensivists. It is richly illustrated for better understanding with some examples of clinical applications of functional echocardiography in the intensive care setting.

Keywords: bedside cardiac ultrasound; echocardiography; functional; intensive care; neonatology; pediatric; point-of-care; target.

Figure 1

Standard echocardiographic image planes from the high left chest just lateral to the sternum [parasternal window (A,B)], the left lateral chest just inferior and lateral to the nipple [apical window (C)], sub-xyphoid area [subcostal window (D,E)], and the suprasternal notch [suprasternal window (F,G)]. Ao, aortic valve; CS, coronary sinus; LA, left atrium; LV, left ventricle; PA, pulmonary artery; RA, right atrium; RV, right ventricle; RVOT, right ventricular outflow tract; SVC, superior vena cava. Adapted from Ref. (1).

Figure 1

Standard echocardiographic image planes from the high left chest just lateral to the sternum [parasternal window (A,B)], the left lateral chest just inferior and lateral to the nipple [apical window (C)], sub-xyphoid area [subcostal window (D,E)], and the suprasternal notch [suprasternal window (F,G)]. Ao, aortic valve; CS, coronary sinus; LA, left atrium; LV, left ventricle; PA, pulmonary artery; RA, right atrium; RV, right ventricle; RVOT, right ventricular outflow tract; SVC, superior vena cava. Adapted from Ref. (1).

Figure 1

Standard echocardiographic image planes from the high left chest just lateral to the sternum [parasternal window (A,B)], the left lateral chest just inferior and lateral to the nipple [apical window (C)], sub-xyphoid area [subcostal window (D,E)], and the suprasternal notch [suprasternal window (F,G)]. Ao, aortic valve; CS, coronary sinus; LA, left atrium; LV, left ventricle; PA, pulmonary artery; RA, right atrium; RV, right ventricle; RVOT, right ventricular outflow tract; SVC, superior vena cava. Adapted from Ref. (1).

Figure 1

Standard echocardiographic image planes from the high left chest just lateral to the sternum [parasternal window (A,B)], the left lateral chest just inferior and lateral to the nipple [apical window (C)], sub-xyphoid area [subcostal window (D,E)], and the suprasternal notch [suprasternal window (F,G)]. Ao, aortic valve; CS, coronary sinus; LA, left atrium; LV, left ventricle; PA, pulmonary artery; RA, right atrium; RV, right ventricle; RVOT, right ventricular outflow tract; SVC, superior vena cava. Adapted from Ref. (1).

Figure 2

M-mode echocardiography (A) obtained from the parasternal long axis view through the right and left ventricular chambers at the tip of the mitral valve leaflets, allowing for the estimation of the fractional shortening. Two-dimensional echocardiography (B) obtained from an apical four-chamber view with tracing of the endocardial LV border during end-diastole and end-systole, allowing for estimation of the ejection fraction. IVS, interventricular septum; LV, left ventricle; LVEDD, left ventricular end-diastolic dimension; LVESD, left ventricular end-systolic dimension; LVPW, left ventricle posterior wall; RV, right ventricle. Adapted from Ref. (12).

Figure 3

Two-dimensional (2D) echocardiography picture (A) obtained from a parasternal long axis view (picture above) showing an echo-free space (yellow arrow) between the two pericardial layer typical of pericardial effusion, and picture obtained from an apical four-chamber view (picture below) showing right atrial free wall collapse (white arrow) consistent with cardiac tamponade. 2D echo picture [(B), above] obtained from a longitudinal subcostal view showing a dilated IVC and M-mode echocardiography [(B) below] showing no respiratory variation of IVC size. IVC, inferior vena cava; LA, left atrium; LV, left ventricle; RA, right atrium; RV, right ventricle.

Figure 4

Spectral Doppler tracing (picture above) from aortic valve stenosis (AS) showing V_max of 2.63 m/s, allowing for estimation of a pressure gradient across the valve of 28 mmHg, consistent with moderate aortic valve stenosis. Spectral Doppler tracing (below picture) from tricuspid regurgitation (TR) showing Vmax of 3.94 m/s, allowing for estimation of a SPAP of 62 mmHg + RAP. RAP, right atrial pressure; SPAP, systolic pulmonary artery pressure.

Figure 5

Spectral Doppler (A) obtained through a VSD with high velocity left-to-right shunt and no pulmonary hypertension (above picture) and with low velocity left-to-right shunt and pulmonary hypertension (below picture). The pressure gradient across the VSD allows for estimation of the systolic PAP. Spectral Doppler (B) obtained through a PDA with high velocity left-to-right shunt and no pulmonary hypertension (above picture) and with low velocity left-to-right shunt and pulmonary hypertension (below picture). The pressure gradient across the PDA allows for estimation of the systolic PAP. BP, systolic blood pressure; LV, left ventricle; PAP, pulmonary artery pressure; PDA, patent ductus arteriosus; RV, right ventricle; VSD, ventricular septal defect.

Figure 6

Schematic representation of pulse-wave and continuous-wave Doppler at the level of the aorta from an apical five-chamber view. Ao, aorta; LA, left atrium; LV, left ventricle; RA, right atrium; RV, right ventricle. Adapted from Ref. (16) (Figure 2).

Figure 7

Comparison of pressure curve of the aorta (Ao), left ventricle (LV), left atrium (LA) and velocity across the left ventricular outflow tract (LVOT) and left ventricular inflow (LV inflow) and spectral Doppler from pulse wave across the LVOT (aortic valve) from apical five-chamber view and LV inflow (mitral valve) from apical four-chamber view. E, early diastolic ventricular filling wave; A, late diastolic ventricular filling during atrial contraction wave. Adapted from Ref. (12).

Figure 8

Color Doppler flow mapping with Blue directed away from the probe and red directed toward the probe: mnemotechnic = BART.

Figure 9

Tissue Doppler imaging (TDI) at the level of the interventricular septum from apical four-chamber view demonstrating the E′, A′, and S′ waves. A′, late diastolic ventricular filling during atrial contraction wave; E′, early ventricular filling wave; S′, systolic wave.