Clinical Investigation
Pulmonary Hemodynamics
Pulmonary Artery Acceleration Time Provides an Accurate Estimate of Systolic Pulmonary Arterial Pressure during Transthoracic Echocardiography

https://doi.org/10.1016/j.echo.2011.03.008Get rights and content

Background

Transthoracic echocardiographic estimates of peak systolic pulmonary artery pressure are conventionally calculated from the maximal velocity of the tricuspid regurgitation (TR) jet. Unfortunately, there is insufficient TR to determine estimated peak systolic pulmonary artery pressure (EPSPAP) in a significant number of patients. To date, in the absence of TR, no noninvasive method of deriving EPSPAP has been developed.

Methods

Five hundred clinically indicated transthoracic echocardiograms were reviewed over a period of 6 months. Patients with pulmonic stenosis were excluded. Pulsed-wave Doppler was used to measure pulmonary artery acceleration time (PAAT) and right ventricular ejection time. Continuous-wave Doppler was used to measure the peak velocity of TR (TRVmax), and EPSPAP was calculated as 4 × TRVmax2 + 10 mm Hg (to account for right atrial pressure). The relationship between PAAT and EPSPAP was then assessed.

Results

Adequate imaging to measure PAAT was available in 99.6% of patients (498 of 500), but 25.3% (126 of 498) had insufficient TR to determine EPSPAP, and 1 patient had significant pulmonic stenosis. Therefore, 371 were included in the final analysis. Interobserver variability for PAAT was 0.97. There were strong inverse correlations between PAAT and TRVmax (r = −0.96), the right atrial/right ventricular pressure gradient (r = −0.95), and EPSPAP (r = −0.95). The regression equation describing the relationship between PAAT and EPSPAP was log10(EPSPAP) = −0.004 (PAAT) + 2.1 (P < .001).

Conclusions

PAAT is routinely obtainable and correlates strongly with both TRVmax and EPSPAP in a large population of randomly selected patients undergoing transthoracic echocardiography. Characterization of the relationship between PAAT and EPSPAP permits PAAT to be used to estimate peak systolic pulmonary artery pressure independent of TR, thereby increasing the percentage of patients in whom transthoracic echocardiography can be used to quantify pulmonary artery pressure.

Section snippets

Methods

All aspects of this study were approved by our institutional review board (Partner’s Human Research Committee). Five hundred (of a total of 9,200) clinically indicated transthoracic echocardiographic studies performed in the Massachusetts General Hospital echocardiography laboratory over a 6-month period (March to September 2009) were randomly selected for retrospective review. To arrive at this total number of participants, a research staff member who was blinded to patient age, gender, and

Results

Among this cohort of randomly selected clinical studies, pulsed-wave Doppler imaging of the main pulmonary artery was sufficient to measure PAAT in 99.6% of patients (498 of 500). In contrast, 25.2% (126 of 500) did not have sufficient TR to measure TRVmax. One individual was excluded from analysis because of the presence of significant pulmonary valve stenosis. As such, 371 individuals were retained in the final analysis.

In the final cohort (n = 317), the mean age was 63 ± 17 years (range,

Discussion

TTE has proven to be an important tool in the noninvasive assessment of pulmonary artery pressures in a wide spectrum of illnesses.6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18 The most widely accepted transthoracic method for the estimation of pulmonary artery pressures relies on the measurement of TRVmax. However, TR is frequently not sufficient to perform this measurement, as demonstrated by the fact that 25% of patients in our randomly selected clinical cohort had insufficient TR for

Conclusions

We have shown that PAAT is easily obtainable and strongly correlated with TRVmax in a large population of randomly selected patients undergoing TTE. Characterization of the relationship between PAAT and EPSPAP now permits PAAT to be used to derive EPSPAP independently of TR. Adoption of this novel method of determining EPSPAP has the capacity to significantly increase the percentage of patients in which TTE can be used to quantify pulmonary artery pressures.

References (27)

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    Nevertheless, the development of moderate-to-severe TR was concerning. While the valvular incompetence was unfortunate, it did facilitate the diagnosis of the patient's PH. Traditionally, the velocity of the TR jet (v) is measured using continuous-wave Doppler, and the right ventricular systolic pressure is estimated by using the following equation: 4v2 + right atrial pressure.37 If she did not have sufficient TR to obtain this measurement, it is possible her diagnosis could have been missed or delayed.

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