FIG 19.45 Apical four-chamber view of a pulmonary venous tracing Notice the biphasic pattern of systolic flow and the monophasic diastolic flow There is a limited reversal of flow during atrial contraction (arrow) The peak systolic and diastolic velocities are measured, permitting calculation of the ratio of systolic to diastolic peak velocity Atrioventricular Valves Velocities of flow through the mitral and tricuspid valves are best recorded from the apical four-chamber view The cursor should be positioned at the tip of the leaflets, with the smallest possible sample volume The flow through the atrioventricular valves is toward the transducer from the apical position and hence is displayed above the baseline The normal pattern shows two waves The E wave occurs during early filling after valvar opening The A wave occurs during atrial contraction (Fig 19.46) In mid-diastole, there is a period of no flow, or diastasis Typically, the velocity of the flow across the mitral valve is greater than that measured across the tricuspid valve However, the tricuspid inflow varies more significantly with respiration compared to the mitral inflow FIG 19.46 Normal pattern of mitral inflow as imaged from the apical fourchamber view The peak E-velocity and peak A-velocity are measured, permitting calculation of the ratio of velocities (E:A ratio) It is also possible to measure the deceleration time of the early peak and the duration of the A wave The peak velocities of the E and A waves are influenced by both age and heart rate.13 In normal children, the mitral E velocity is larger compared with the A velocity, whereas in normal newborns the mitral A velocity is larger than the E velocity This is thought to be related to immaturity of the myocardium, especially in handling of calcium metabolism, resulting in slower early relaxation, and large dependency on filling during the period of atrial contraction The inflow velocities are used to assess diastolic function, especially of the left ventricle This is because abnormalities of relaxation, as well as decreased compliance and increased ventricular stiffness, will affect the inflow patterns However, discussion of assessment of diastolic dysfunction is beyond the scope of this chapter Atrioventricular valvar stenosis is associated with increased velocities of flow, and continuous wave Doppler can be used to quantify the degree of stenosis, as discussed later Right Ventricular Outflow Tract and Pulmonary Trunk Velocities in the right ventricular outflow tract and pulmonary trunk are best recorded from the subcostal position or from the left parasternal short-axis views To align better with the flow, it is useful to position the transducer one or two rib spaces lower compared with the standard parasternal position When the transducer is tilted superiorly, flow through the outflow tract will be aligned with the Doppler beam Flow is directed away from the transducer and is displayed below the baseline (Fig 19.47) Anterograde flow occurs during systole, although some anterograde flow can occur in late diastole concomitant with atrial contraction during inspiration because at that time pressure in the right ventricle can exceed diastolic pressure in the pulmonary arteries This can result in late diastolic opening of the pulmonary valve, especially with inspiration when there is increased pulmonary venous return to the heart Normally there is no flow in the pulmonary arteries during diastole, although a small amount of reversal of flow can occur early after closure of the pulmonary valve due to some backflow associated with valvar closure The mean normal peak velocity across the pulmonary valve is 0.9 m/s, with a range from 0.7 to 1.1 m/s If a leftto-right shunt is present, increased flow across the pulmonary valve at increased velocity is noted This increased velocity needs to be distinguished from associated obstruction in the right ventricular outflow tract In this setting, crosssectional imaging to look for muscle bundles, infundibular stenosis, pulmonary valvar motion, and to inspect changes in dimension in the supravalvar region, is an important adjunct FIG 19.47 Pulsed wave Doppler profile of normal flow in the pulmonary trunk as seen from the parasternal short-axis view The acceleration of flow is slower compared with that seen in the left ventricular outflow tract and the aorta Left Ventricular Outflow Tract, Ascending and Descending Aorta Velocities in the left ventricular outflow tract are best recorded from the apical five- or three-chamber view The Doppler velocities recorded from this position