5.1 Tissue Doppler and Hemodynamic Sample Placement

Tissue Doppler measures motion, not blood flow

Spectral tissue Doppler imaging, or TDI, uses Doppler principles to display the relatively low-velocity, high-amplitude motion of myocardium and valve annuli. Conventional spectral Doppler suppresses tissue signals to display faster blood flow; a TDI preset changes filters, gain, scale, and processing to preserve tissue motion. A blood-flow preset with the sample placed near an annulus does not become valid TDI, and color TDI values are not automatically interchangeable with pulsed spectral TDI values.

From a true apical window, align the cursor as parallel as possible to longitudinal annular motion. Place the pulsed sample at the septal and lateral mitral annulus, not in the leaflet tips, midmyocardium, or cavity. ASE's comprehensive adult TTE protocol describes a 5- to 10-mm sample for annular motion, a low velocity scale adjusted to enlarge the signal, and a 100-mm/sec sweep speed. Use the manufacturer and laboratory preset because systems display and filter tissue signals differently. Keep gain low enough to preserve a clear modal envelope without losing the waveform.

The principal components are s′ during systole, e′ during early diastolic relaxation, and a′ during atrial contraction. In the usual apical display, s′ is above baseline and e′ and a′ are below, although the machine's invert setting can reverse the display. Label by cardiac timing, not screen direction alone. Atrial fibrillation lacks a consistent a′, tachycardia can fuse components, pacing can alter timing, and an ectopic or postectopic beat may be unrepresentative.

Sample placement is a hemodynamic decision

Pulsed Doppler localizes velocity to a selected range, so moving a sample a few millimeters may change the physiology being measured. Map first with 2-D and color, then place the gate where the question is defined. For mitral inflow, a 1- to 3-mm sample at the open leaflet tips records E and A. For LVOT velocity-time integral, use the center of laminar outflow about 5 mm proximal to the valve and match the diameter-measurement level. A narrow envelope with a closing click supports placement; broadening or higher velocities suggest movement too close to the valve.

For right ventricular outflow, sample just proximal to the pulmonic valve from the view with the best alignment. Pulmonary venous flow is commonly acquired roughly 1 cm into a pulmonary vein from the atrial junction, while hepatic venous flow is acquired about 1 to 2 cm from its IVC junction and observed through respiration. Exact gate sizes and required measures follow the governing protocol. Continuous-wave Doppler is chosen when the highest velocity along the whole beam is needed and range specificity is unnecessary; it should not replace PW mapping when location matters.

Do not use angle correction to rescue a poor cardiac Doppler line. Reposition the transducer, choose another window, and align the beam with motion or flow. The cosine effect underestimates velocity as alignment worsens. With TDI, a sample that straddles annulus, wall, and blood may show competing signals. With flow Doppler, an oversized gate can include adjacent acceleration or wall artifact. Optimize scale so the waveform fills the display without clipping, set baseline to reveal all components, and trace the dense modal edge rather than noise.

Interpret the acquisition before the number

Mitral E/e′ combines transmitral blood velocity with annular tissue velocity, but a ratio is only as sound as both acquisitions. Use representative beats under comparable rhythm and loading, preserve septal and lateral labels, and follow current diastolic algorithms rather than diagnosing filling pressure from one ratio. Annular calcification, mitral surgery or prosthesis, regional dysfunction, conduction abnormalities, and constriction can limit assumptions. TDI e′ is less load sensitive than mitral E, not load independent.

For RV TDI, current ASE right-heart guidance places a small sample at the basal RV free wall along the lateral tricuspid annulus in an RV-focused view, with the contraction axis within about 20 degrees of the beam. S′ is the peak systolic velocity, but translation, tethering, severe tricuspid regurgitation, pacing, and loading affect it. Integrate it with RV size, fractional area change, TAPSE, strain, and clinical context in later interpretation.

Before saving, confirm site, label, sweep speed, scale, gain, complete waveform, ECG timing, rhythm, and representative beats. If lateral e′ is unexpectedly lower than septal e′, inspect the image and sample first instead of swapping labels or averaging blindly. Reacquisition is the quality response to questionable placement; a plausible numeric value is not proof of a valid signal.

Gate first, number second

Identify the anatomic site and physiologic question before placing the PW sample. A clean tracing from the wrong location is a precisely recorded wrong answer.