Echo Pulmonary Vein Doppler

Table modified from Garcia MJ, Thomas JD, Klein AL. New Doppler echocardiography applications for the study of diastolic function. J Am Coll Cardio 1998;32:865-875. "Unless atrial mechanical failure present.

AR, pulmonary venous peak atrial contraction reversal velocity; EDT, early left ventricular filling deceleration time; IVRT, isovolumic relaxation time; S/D, systolic-to-diastolic pulmonary venous flow ratio.

Table modified from Garcia MJ, Thomas JD, Klein AL. New Doppler echocardiography applications for the study of diastolic function. J Am Coll Cardio 1998;32:865-875. "Unless atrial mechanical failure present.

AR, pulmonary venous peak atrial contraction reversal velocity; EDT, early left ventricular filling deceleration time; IVRT, isovolumic relaxation time; S/D, systolic-to-diastolic pulmonary venous flow ratio.

of early LV filling and the greater contribution by atrial contraction, patients with this pattern of MV inflow often are poorly tolerant of tachycardia (decreased diastolic filling period) and atrial fibrillation (loss of atrial kick). This pattern has been designated as grade 1 diastolic dysfunction. The grades of diastolic dysfunction are summarized in Table 3.

Pseudonormal MV Inflow

If elevated intracardiac filling pressures are superimposed upon impaired LV relaxation, the Doppler pattern of mitral inflow can again appear normal, with an E:A ratio greater than 1 and decreased E-wave deceleration time (Fig. 7). This occurs because increased LA pressure re-establishes a higher gradient between the LA and the LV, providing a larger pressure head to drive LV filling in early diastole. The result is a higher peak E-wave velocity and more rapid filling (decreased E-wave deceleration time). The fact that this apparently normal pattern occurs in the presence of impaired LV relaxation and elevation of left-sided filling pressures underlies the problem with using mitral inflow profiles as the sole measure of diastolic function (Fig. 6). This pattern has been designated as grade 2 diastolic dysfunction.

Restrictive Mitral Inflow

With further progression of diastolic dysfunction and rise in filling pressures, LV filling can become restrictive with an increase in peak E-velocity (owing to a higher transmitral gradient resulting from increased LA pressures), marked shortening of the E-wave deceleration time (owing to rapid equilibration of LA and LV diastolic pressures in the noncompliant LV), and a diminutive A-wave (owing, in part, to high LV diastolic pressures and coexistent atrial systolic dysfunction). The result is a tall, thin E-wave and small A-wave with the bulk of LV filling occurring over a very brief period of time in early diastole (Fig. 7). This pattern has been designated as grade 3 diastolic dysfunction (if the pattern is reversible) or grade 4 (if the pattern is irreversible; see next section). The development of restrictive mitral inflow can be an ominous sign in patients with heart failure. A cohort of patients with advanced heart failure who showed an irreversibly restrictive pattern had a worse prognosis and increased mortality as compared to patients who did not have this pattern.

Altering MV Inflow Patterns

Because MV inflow, particularly the E-wave, is highly dependent on loading conditions, maneuvers that alter preload can alter patterns of mitral inflow. In addition to demonstrating the underlying pathophysiol-ogy, performing these maneuvers simultaneously with echocardiography may assist in discriminating between normal and pseudonormal filling. Decreasing LV preload (nitroglycerin administration, diuresis) is associated with a decrease in peak E-wave velocity and E-wave deceleration time. Thus, the underlying impairment of LV relaxation may be unmasked by this maneuver, with the caveat that even individuals with normal LV relaxation may appear to have an impaired relaxation pattern with excessive volume depletion. If a patient has a restrictive pattern of MV inflow, decreasing preload may cause a transition to a pseudonormal pattern. If this can be accomplished, it is associated with a better prognosis than an irreversibly restrictive pattern.

Increasing LV preload (intravenous fluid bolus, passive leg raising) increases peak E-wave velocity and decreases E-wave deceleration time. Thus, a patient with an impaired relaxation pattern at baseline may develop a pseudonormal pattern; a patient with a pseudonormal pattern may appear restrictive.

pv doppler flow patterns

Evaluation of PV flow provides further information about LV diastolic function and can be used to more accurately interpret mitral filling patterns. There are typically three components of PV flow (Fig. 8): (1) S-wave, during ventricular systole. Forward flow from the pulmonary veins to the LA is driven by atrial relaxation and apical descent of the mitral annulus during ventricular systole. There may be two components to the S-wave; (2) D-wave, during ventricular diastole. Diastolic flow is largely passive and follows mitral inflow from LA to LV; (3) Ar-wave, atrial reversal as the force of atrial contraction forces a small amount of blood retrograde from the LA to the pulmonary veins.

As with mitral inflow, the pattern of PV flow varies with age. In children and young adults, the typical pattern is S < D-wave. During adulthood, S > D is the normal pattern (Fig. 8). Impaired LV relaxation may be perceived as increased atrial afterload and lead to decreased LA compliance and impaired atrial relaxation. This is reflected by blunting of the PV S-wave such that it is lower than the D-wave. Decreased LV compliance may also lead to an increase in the peak velocity and duration of the atrial reversal wave, as blood flows preferentially into the pulmonary veins rather than into the noncompli-ant LV. Thus, integration of PV flow patterns may assist with the proper interpretation of mitral flow patterns in the assessment of diastolic function (Fig. 9). If a normal-appearing MV inflow pattern is accompanied by a PV pattern with S < D and/or an increased Ar-wave, it may be more correctly interpreted as pseudonormalized (Table 3).

Technical Issues in Measuring PV Flow

1. Obtain an apical four-chamber view with slight anterior angulation (Fig. 10). Color flow Doppler may be used to help localize PV flow.

2. In pulse wave Doppler mode, a 2- to 3-mm sample volume is placed 1-2 cm into the pulmonary vein. Typically the right upper pulmonary vein is most optimally aligned with the transducer beam in this view, but all may be sampled to obtain the best spectral pattern.

3. The velocity filter setting should be as low as possible. If the Doppler signal is weak or incomplete, a 4- to 5-mm sample volume, higher Doppler gain or supine positioning of the patient may be helpful.

Fig. 8. Normal pulmonary venous flow patterns. Doppler patterns of pulmonary venous flow in a normal 18-yr-old male (A) and a normal 68-yr-old female. Note the typical S < D pattern in children and young adults and the typical S > D pattern in older adulthood.

Pulmonary Venous Doppler Young

Fig. 8. Normal pulmonary venous flow patterns. Doppler patterns of pulmonary venous flow in a normal 18-yr-old male (A) and a normal 68-yr-old female. Note the typical S < D pattern in children and young adults and the typical S > D pattern in older adulthood.

isovolumic relaxation time

The isovolumic relaxation time (IVRT) of the LV is the time interval between aortic valve closure to MV opening and the start of transmittal flow. This is influenced by the rate of LV relaxation and LA pressure. Excessive prolongation of IVRT (>100 ms) is associated with impaired relaxation, whereas abnormal shortening of IVRT (<60 ms) is associated with elevation of LA pressure. This time interval is typically measured from Doppler recordings, which display the transient of aortic valve closure and the spectral pattern of mitral inflow.

2. If the results are suboptimal, CW Doppler can be used with similar positioning, to simultaneously record aortic and mitral flow. IVRT is measured as the time between the cessation of aortic flow and the onset of mitral flow.

advancements in the assessment of diastolic function

Doppler Tissue Imaging

Doppler tissue imaging (DTI), also known as tissue Doppler imaging (TDI), enables the measurement of the high amplitude, low velocity signals of myocardial motion, rather than blood flow velocities as with standard Doppler interrogation. This is accomplished by bypassing the high pass filter (to pick up strong signal reflections from the myocardium) and using low gain amplification (to eliminate weaker blood flow signals) (Fig. 12; see companion DVD for corresponding video). The main advantage of DTI information is that it is less load-dependant than standard Doppler. The assessment of early myocardial relaxation velocities provides an additional window on LV diastolic function

Technical Issues in Recording IVRT

1. From an apical view using PW Doppler, position a 3- to 4-mm sample volume near the mitral leaflet tips to display mitral inflow. The transducer beam is then angulated toward the LV outflow tract until the transient of aortic valve closure appears above and below the baseline. IVRT is measured as the time interval between the aortic valve transient and the onset of mitral inflow (Fig. 11).

Normal Older adult or Young Adult Impaired relaxation

A r\ A A

Diastolic Dysfunction

Vein 60

Flow 40

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