Normal pulmonary venous Doppler

The patterns of blood flow in the pulmonary veins may be investigated during echocardiography with spectral Doppler analysis. Perturbations in the normal pulmonary venous waveform may indicate the presence of diastolic dysfunction and elevated filling pressures in the left atrium and ventricle. 

Radiographic features

Pulsed wave Doppler (PWD) of the right superior pulmonary vein, which one may insonate from an apical four chamber view (A4C), will typically yield a waveform with three positive deflections (S1,S2,D) and one negative deflection (AR) ¹. 

• systolic deflections
  • positive, referred to as S1 and S2, often indinguishable and simply referred to as the S wave
  • the first (S1) component denotes atrial diastole, with suction of blood into the left atrium
    • abolished with atrial fibrillation
  • the second (S2) component occurs when the mitral annulus is apically displaced with ventricular systole, decreasing left atrial pressure and creating a gradient for forward flow
    • blunted by mitral regurgitation
• diastolic deflections
  • normally a prominently positive, albeit more diminutive, deflection following the sequential systolic components
    • referred to as the D wave
  • atrial reversal
    • the downstroke of the D wave will often dip below the baseline, indicating flow away from the transducer
    • referred to as the AR wave, corresponding to atrial contraction and "reversal" of flow
      • positively correlated with inotropic function of the left atrium

Differential diagnosis

While various pathological entities may disturb flow through the pulmonary veins, a series of predictable changes in the aforementioned waveforms occurs during the progression of diastolic dysfunction. A progressive increase in left atrial pressure will blunt the systolic flow velocities in the pulmonary veins, with the majority of forward flow increasingly occurring during diastole. The elevation in left ventricular end diastolic pressure, secondary to lusitropic incompetance, will exaggerate the flow reversal that occurs with atrial contraction, prolonging the AR wave ⁴.

• diastolic dysfunction on pulmonary venous Doppler
  • the S/D ratio
    • normal filling patterns are predominantly systolic, with an S/D ratio > 1
    • a pathologic increase in mean left atrial pressure will reverse this pattern, resulting in an S/D ratio < 1 and a diastolic filling predominance
    • progressive increase in amplitude of D wave and decrease in S wave with increasing filling pressures
  • atrial reversal velocity and duration
    • normally the peak of the AR wave is < 35 cm/s
    • a peak velocity exceeding this upper limit implies elevated filling pressures
    • the AR wave duration is typically examined in concert with the mitral inflow velocities
      • the transmitral A wave and the pulmonary venous AR wave should be roughly similar in length
      • the duration of the latter should only exceed the former by < 20 m/s, with greater discrepancies occurring with elevated filling pressures ³
      • a sensitive indicator of pseudonormalization of the filling pattern (stage III diastolic dysfunction)
• atrial fibrillation on pulmonary venous Doppler
  • abolition of organized atrial contraction decreases the peak of the S1 wave and decreases the peak velocity of the AR wave
• elevated lusitropy on pulmonary venous Doppler
  • the enhanced relaxation found in young patients may also reverse the S/D ratio and mimic advanced diastolic dysfunction
  • vigorous left ventricular suction results in elevated peak D wave velocities, with a restrictive transmitral filling pattern
  • if doubt exists regarding the consequence of these findings, tissue Doppler of the mitral annulus is required