Hemodynamic Precision in the Neonatal Intensive Care Unit using Targeted Neonatal Echocardiography

1 When TnECHO is integrated with clinical findings, 2 it allows for formulation of a diagnostic impression, 3 individualized guidance 4 for selecting cardiovascular therapies, 5 and dynamic monitoring of response to treatments. 6 A standard targeted neonatal echocardiography7 includes key measurements 8 that allow comprehensive assessments 9 of intricate cardiovascular physiology 10 during the neonatal period and beyond, 11 especially in preterm-born infants 12 predisposed to chronic pulmonary hypertension. 13 Applying a multi-parametric hemodynamic approach 14 using targeted neonatal echocardiography 15 allows for quantitative analysis, 16 thus increasing the refinement of clinical decision-making.

17 Image acquisition skills18 and a comprehensive understanding 19 of neonatal cardiovascular physiology are imperative. 20 We recommend formal neonatal hemodynamics training 21 per the ASE 2011 recommendations. 22 The visual demonstration of this method 23 gives the audience an understanding 24 of the echocardiographic views 25 and attributes of different disease processes.

26 To begin, place the probe on the apex27 with the position marker angling toward the left shoulder. 28 Click 2D to start the first image, 29 and then click the up/down button 30 on the interactive touchscreen 31 to orient the apex of the heart at the bottom of the screen. 32 Click Color on the console 33 and place the color box over the tricuspid valve 34 using the track ball.

35 Adjust the velocity reset to a color scale 36 of 70 to 80 centimeters per second. 37 Then click on the cursor and use the track ball 38 to place the sample gate over the tricuspid valve. 39 Press the continuous wave Doppler button 40 to obtain the tricuspid regurgitant peak velocity 41 and click Freeze, followed by Image Store.

42 Next, click 2D to reset the screen. 43 Click Color and then simultaneous buttons 44 to activate color Doppler. 45 Use the track ball to place the color box 46 over the pulmonary veins.

47 Adjust the velocity and decrease the color Doppler 48 to 50 to 60 centimeters per second. 49 Click on the cursor 50 and place the sample gate over the pulmonary vein. 51 Click Pulsed Wave Doppler to obtain the pulsed wave.

52 Save this by clicking Freeze, followed by Image Store. 53 Similarly, click on the cursor and place the sample gate 54 at the tips of the open mitral valves. 55 Click Pulsed Wave Doppler 56 to obtain the mitral valve E/A ratio.

57 Click Freeze, followed by Image Store. 58 Rotate the probe clockwise to open 59 and visualize the left ventricular outflow tract. 60 Click cursor, place the sample gate at the mitral inflow 61 and outflow junction, and then click Pulsed Wave Doppler 62 to obtain the pulsed wave.

63 Click Freeze, followed by Image Store to save the image. 64 Place the sample gate at the aortic valve 65 and follow the same procedure to capture the image. 66 To focus on the left ventricular outflow tract, 67 turn the width button to narrow the sector width, 68 place the sample gate over the aortic valve 69 at the level of the hinge points 70 and repeat the same steps shown earlier.

71 Click the TVI button on the console 72 to activate tissue Doppler imaging. 73 Turn the width button to narrow the sector width 74 to interrogate the septum with a target frame rate 75 greater than 200 frames per second. 76 Place the sample gate below the mitral valve annulus 77 in the wall of the septum.

78 Click Tilt to move the sector 79 to focus on the lateral wall of the left ventricle 80 and maintain the frame rate 81 at greater than 200 frames per second. 82 Place the sample gate 83 below the mitral valve annulus in the wall. 84 Move the sector to focus on the lateral wall 85 of the right ventricle.

86 Then click Tilt and place the sample gate 87 in the lateral wall of the right ventricle. 88 Next, use the track ball to place the line of insonation 89 at the tricuspid valve annulus 90 perpendicular to the free wall hinge point 91 of the tricuspid valve. 92 Click the M Mode button on the console 93 for tricuspid annular plane systolic excursion.

94 For transition to the apical two chamber view, 95 rotate the probe counterclockwise 96 and click Image Store for 2D images. 97 Click TVI, followed by Image Store to obtain TDI images. 98 For the apical three chamber LV view, 99 turn the probe counterclockwise and click Image Store.

100 Turn the width button to narrow the sector 101 to the anterior wall and follow the steps shown earlier. 102 For the apical three chamber RV view, 103 turn the width button to completely visualize 104 the right ventricle lateral wall. 105 Use the track ball to place the color box 106 over the tricuspid valve.

107 Place the sample gate over the tricuspid valve 108 where the blue jet is observed 109 and follow the steps shown earlier. 110 Use the track ball to move the color box 111 over the pulmonary artery. 112 Click cursor and place the sample gate 113 over the pulmonic valve.

114 Then obtain the pulsed wave Doppler 115 and the continuous wave Doppler 116 of the right ventricular outflow. 117 Click on Freeze, followed by Image Store to save the image. 118 For obtaining a parasternal long axis view, 119 place the probe straight down on the third 120 or fourth intercostal space just to the left of the sternum 121 with the notch pointing toward the right shoulder.

122 Click 2D and the up/down tab on the interactive control 123 to orient the right ventricle at the top of the screen 124 and click Image Store, followed by cursor. 125 Place the line of insonation 126 through the left ventricle 127 at the tips of the mitral valve leaflets, 128 ensuring that the line is perpendicular 129 to the intraventricular septum 130 and that the left ventricle is not foreshortened. 131 Click M Mode, Freeze, and Image Store.

132 Turn the width button and focus on the aortic valve. 133 Turn the depth knob to adjust the depth 134 or turn the zoom button on the console 135 to view the aortic annulus. 136 Click cursor and place the line of insonation 137 through the aortic valve annulus and left atrium 138 or left atrium and aortic dimensions.

139 Click M Mode, Freeze, and Image Store. 140 Move the probe in an angling motion from the aortic arch 141 toward the pulmonary artery 142 by angling the probe toward the right flank. 143 For the aortic arch view, 144 place the sample gate at the pre-ductal aortic arch 145 and then at the post-ductal arch below the level of ductus.

146 For the high parasternal view, click the Freeze button twice 147 to obtain the ductal view with a color sweep 148 of patent ductus arteriosus, or PDA. 149 Click Freeze, Select All, and Image Store. 150 In the presence of a PDA, click cursor, 151 place the sample volume at the narrowest point of the PDA, 152 obtain the pulsed wave, and save the image.

153 For the subcostal view, 154 the probe is positioned in a transverse fashion 155 with the probe mark pointing to the left of the infant. 156 For the sagittal subcostal view, 157 the probe is situated between the xiphoid process 158 and the umbilicus in the midline 159 with the probe mark pointing toward the head of the patient. 160 Angle the probe tilting toward the left of the patient 161 to visualize the inferior vena cava and the hepatic vein 162 and continue tilting toward the left 163 to visualize the abdominal aorta, celiac artery, 164 and superior mesenteric artery.

165 Finally, place the sample gate at the vessels. 166 The echocardiographic results are rated 167 using a rating system such as the Iowa PDA score. 168 This scoring system assesses the surrogate consequences 169 of volume loading on the heart and systemic hypoperfusion 170 associated with patent ductus arteriosus shunt.

171 The representative results of a case vignette 172 to illustrate the echocardiography 173 performed using this protocol 174 and the Iowa PDA score are shown here. 175 A premature male infant received the targeted 176 neonatal echocardiography evaluation at two days of life 177 to assess the hemodynamic significance of PDA. 178 The evaluation measurements 179 gave the Iowa PDA score of eight, 180 suggesting hemodynamically significant PDA.

181 Precision in image acquisition182 which includes appropriate alignment, angle of insonation, 183 and accuracy of the image plane 184 is important for this technique. 185 Misalignment or foreshortening of the images 186 can result in inaccurate measurements. 187 In the case of chronic pulmonary hypertension, 188 TnECHO offers non-invasive screening 189 and assesses the need for a definitive diagnostic evaluation 190 with cardiac catheterization.

191 The ongoing advancements in TnECHO and neonatal hemodynamics 192 can yield significant clinical improvement 193 in the care of our most vulnerable patients in the future.