Echocardiographic Assessment
Most echocardiograms were performed on a Philips IE33 system (Philips
Medical Systems, Andover, Mass. USA) with an age and size appropriate
probe (S8 or S12). The small remainder were performed on GE Vivid Q
(General Electric Corporation, Milwaukee, USA) with an age and size
appropriate probe. Atrial septal Doppler assessment was performed from a
subcostal view; pulmonary artery band Doppler interrogation were usually
obtained using a high parasternal view and interrogated with continuous
wave Doppler.
On each of the echocardiograms, the atrial septal Doppler along with
each pulmonary artery band Doppler was reviewed. The atrial septal
Doppler wave was traced over two cardiac cycles to calculate the mean
transatrial gradient (IAS) (Figure 1). The pulmonary artery band Doppler
for the right (RPA) and left (LPA) pulmonary artery bands was traced
over two cardiac cycles. The mean velocity and VTI were measured as well
as the peak systolic velocity (S vel) and diastolic velocity (D vel)
(Figure 2). The systolic to diastolic velocity ratio (S vel: D vel) was
calculated, along with the pulsatility index ((systolic velocity minus
diastolic velocity) divided by the mean velocity, PI). Additionally, the
shape of the traces was recorded as either sawtooth or pulsatile, along
with the presence of any notching of the descent (Figure 3).
One operator performed all measurements (HBR). Intra-user variability
was tested by the same operator measuring the parameters on 5
echocardiograms >3 weeks after the initial measurements.
Another operator (EK) measured the parameters on the same 5
echocardiograms to assess inter-user variability.