Measurement of Pulmonary Diastolic Pressure

Color Doppler, parasternal short axis view of the base of the heart, with leftward tilt of transducer to image pulmonary valve and right ventricular outflow tract (RVOT).

Mild, central pulmonary valve regurgitation is evidenced (red / yellow jet directed towards anterior wall of RVOT). Subsequently, Continuous wave Doppler scan line is placed parallel and central to regurgitant jet to record diastolic velocities (see below).

Peak end-diastolic regurgitant velocity (+) is measured after the indentation (arrows) caused by right atrial contraction. Using the simplified Bernouilli equation, the ultrasound machine displays the corresponding pressure gradient occurring in end-diastole between the pulmonary artery and the right ventricle (RV).

The diastolic (=end-diastolic) pulmonary artery pressure is calculated by adding the estimated (observing the degree of inferior vena cava inspiratory collapse , 2D subcostal imaging) right atrial pressure (= to RV end-diastolic pressure) to the pul,onary artery – RV pressure gradient.

Pulmonary artery diastolic pressure = (pulmonary artery – RV pressure gradient) + right atrial pressure

LV outflow tract diameter measurement

Figure 1. When the left ventricular outflow tract (lvot) diameter is difficult to visualize in the parasternal long axis view, adding color Doppler may help in delineating the septal endocardium just proximal to the aortic valve annulus (Figure 1, green arrow), where lvot diameter has to be measured. In Figure 1, blue systolic velocities in the lvot help the positioning of the caliper (Figure 2) (blue cross) on the septal endocardium.

Figure 2

2D Aortic Arch measures

Suprasternal (jugular) 2D longitudinal view of aortic arch.
Measures: A. proximal arch; B. mid-arch; C. distal arch. AA: ascending aorta; TA: anonymous art. (brachiocephalic); CA: left carotid; SU: left subclavian art.

Measures should be performed “inner edge” to “inner edge”. I prefer to measure the arch at the “exit” point (C), which is also the (normal) smaller diameter, immediately distal to the left subclavian artery. When in doubt about the anatomy (poor image resolution), adding color Doppler may help identify the lumen of the aortic arch, and the correct diameter (gain should be kept low to avoid shadowing of the anatomy of the walls by “overflowing” color signal).

Paolo Barbier

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