Pulmonary Artery Pressure in Young Healthy Subjects


Pulmonary artery systolic pressure (PASP) is frequently measured noninvasively using transthoracic echocardiography. Normal values of PASP are based on studies performed in heterogeneous populations. The normal values of PASP in young healthy subjects are poorly defined. The aim of this study was to describe the distribution and clinical and morphologic correlates of PASP values in young healthy subjects.


Echocardiography is routinely performed for aircrew candidates for the Israeli Air Force. All echocardiographic examinations performed between 1994 and 2010 in which tricuspid regurgitation was present, a prerequisite for echocardiographic PASP measurement, were collected. Subjects with morphologic abnormalities were excluded. PASP was calculated using the simplified Bernoulli equation, with right atrial pressure assumed to be 5 mm Hg. The associations between PASP and clinical and echocardiographic characteristics were studied.


Subjects were healthy young adults aged 17 to 29 years. Evidence of tricuspid regurgitation was found in 1,900 of 6,598 subjects. The estimated mean PASP value was 31.2 ± 4.5 mm Hg, and the upper 95th percentile was 34 mm Hg. In univariate analysis, PASP was correlated with left ventricular end-diastolic and end-systolic diameters. A multivariate linear regression model including age; diastolic blood pressure; echocardiographic measurements of aortic root, left atrial, and left ventricular end-diastolic diameters; and left ventricular mass explained only 7% of the variability in PASP.


PASP in young, physically fit subjects may be higher than previously reported in the general population and is poorly explained by age, blood pressure, and other echocardiographic parameters.

Transthoracic echocardiography has been validated for the noninvasive assessment of cardiac structure and function in healthy subjects and patients with heart disease. Estimation of right ventricular systolic pressure by Doppler transthoracic echocardiographic assessment of tricuspid regurgitation (TR) jet peak velocity accurately predicts pulmonary artery systolic pressure (PASP) measured invasively. Studies have demonstrated that PASP is associated with various characteristics, including sex, age, body mass index (BMI), and systemic blood pressure. However, the studies used to set the normal range for PASP included subjects aged > 45 years. Thus, the normal values for PASP in young subjects are poorly defined.

Aircrew candidates for the Israeli Air Force (IAF) undergo universal transthoracic echocardiography as a part of the medical screening process. The unique setting of screening echocardiography performed in healthy young adults allowed us to characterize the distribution of and correlates with PASP values in this population.


Study Population

The study population consisted of voluntary flight academy candidates aged 17 to 29 years, who were all previously screened to exclude significant medical conditions, including cardiovascular and respiratory diseases. All candidates with BMIs > 30 kg/m 2 are disqualified from the flight academy and thus were excluded from the study. Candidates were evaluated by an examiner at the IAF Aero Medical Center (AMC). Medical history, physical examination, and a 12-lead resting electrocardiogram were obtained for all candidates. Candidates who had normal results on medical evaluation and completed an additional nonmedical screening process underwent transthoracic echocardiography at the AMC. Only those with normal results on echocardiography were included in the study. The study was performed retrospectively on the basis of the routine examinations performed in air force academy candidates. The results recorded were reviewed by a technician to ensure that no abnormal values were present. If abnormal values were identified, the test was reviewed, and the correct data were recorded. All data were also reviewed by a statistician, and again any values identified as abnormal were reviewed through the original medical records.

Echocardiographic Studies

We reviewed all routine echocardiographic studies of aircrew candidates performed at the AMC between January 1994 and January 2010. Studies were performed whether abnormal clinical findings (e.g., on physical examination or electrocardiography) were present or not.

All echocardiographic studies were obtained with one of three devices (HP 500 Sonos, ATL 5000HDI [Palo Alto, CA], or Philips HD 11 XE [Amsterdam, The Netherlands]). Second-generation devices (HP 500 Sonos and ATL 5000HDI) were used from 1994 to 2008. A third-generation device (Philips HD 11 XE) was used from 2008 onward. All studies were performed by one of three experienced sonographers and interpreted by one of two cardiologists specialized in echocardiography. Transthoracic echocardiography included two-dimensional, M-mode, and Doppler studies according to standard American Society for Echocardiography guidelines for obtaining images, quantification of chamber dimensions, and assessment of valvular regurgitation. All studies performed at the IAF AMC are performed in four windows. The first and second are the left and right parasternal long-axis views. The third window is the parasternal short-axis view, and the fourth is the apical four-chamber view. In cases in which elevated PASP or TR is suspected on the basis of these four windows, a subcostal window is added. All TR gradients were measured during the inspiratory phase. No saline injection was used in an attempt to enhance weak signals. Measurements were corrected for body surface area. Left ventricular mass was estimated as 1.05 × {[left ventricular end-diastolic diameter (mm) + posterior wall thickness (mm) + intraventricular septum (mm)] 3 − [left ventricular end-diastolic diameter] 3 }/1,000. Right ventricular systolic pressure is equivalent to systolic pulmonary artery pressure. The pressure gradient across the tricuspid valve was derived from tricuspid systolic regurgitant flow velocity, measured by continuous-wave Doppler, using the simplified Bernoulli equation. Right atrial pressure was estimated as 5 mm Hg. Thus, the right ventricular systolic pressure estimation equaled the tricuspid pressure gradient + 5 mm Hg. Right ventricular systolic pressure is considered to be equal to PASP.

Tests in which cardiac abnormalities were identified (with the exception of TR or elevated pulmonary artery pressure) or in the absence of measurable regurgitant tricuspid flow were excluded from the study.

The study was approved by the ethics committee of the Medical Corps of the Israel Defense Force (IDF-685-2007).

Statistical Analysis

Continuous variables are presented as mean ± SD if normally distributed or as median (interquartile range) otherwise. Spearman’s correlation analysis was used to assess the univariate correlations of PASP with age, blood pressure, and echocardiographic parameters. Multivariate linear regression analyses were performed to assess the independent contribution of age, blood pressure, and echocardiographic measures to PASP variance. The selection of variables for inclusion in the model was based on clinical judgment and univariate correlations detected. The assumption of normality was tested by evaluation of the distribution of the model residuals. Variance inflation factors were examined to detect possible collinearity between variables in the model. Variance inflation factors did not exceed 3 for all variables in each model, indicating lack of collinearity. Data were analyzed using SAS version 9.2 (SAS Institute Inc., Cary, NC).


A total of 6,598 subjects underwent routine echocardiography at the IAF AMC from 1994 to 2010 that were interpreted as having normal results. In 257 examinees with minimal or borderline TR and 168 subjects with mild TR, PASP could not be measured. Of the remaining examinations, 1,900 studies demonstrated TR enabling measurement of PASP. Pulmonary artery pressure was measured in 37% of tests performed using second-generation devices (HP 500 Sonos and ATL 5000HDI) and in 29% of tests performed using third-generation devices (Philips HD 11 XE).

Demographic and clinical characteristics and echocardiographic measurements are presented in Table 1 . The mean age was 18.3 ± 1.0 years, and most subjects were men (94%). Clinical variables and echocardiographic parameters were within normal limits.

Table 1

Demographic and clinical characteristic of 1,900 flight candidates with TR

Clinical parameter Value
Age (y) 18.3 ± 1.0
Men 1,785 (94%)
Body surface area (m 2 ) 1.8 ± 0.1
Blood pressure (mm Hg)
Systolic 125 ± 12
Diastolic 70 ± 9
Heart rate (beats/min) 70 (62–80)
Echocardiographic parameters
Aortic root (mm) 28.5 ± 2.3
Left atrial diameter (mm) 33.3 ± 3.4
Left ventricular end-diastolic diameter (mm) 50.9 ± 3.3
Left ventricular end-systolic diameter (mm) 31.1 ± 3.3
Septum (mm) 9.0 ± 0.8
Posterior wall (mm) 8.6 ± 0.9
Left ventricular mass (g) 201.6 ± 32.9
Shortening fraction (%) 39.0 ± 4.8

Data are expressed as mean ± SD, number (percentage), or median (interquartile range).

PASP values were nearly normally distributed, with a mean of 31.2 ± 4.5 mm Hg ( Figure 1 ). The estimated 95th and 99th percentiles for PASP among subjects evaluated were 34 and 39 mm Hg, respectively.

Figure 1

Distribution of PASP values among the study population.

PASP was significantly inversely correlated with age and aortic root diameter and positively correlated with left atrial diameter, left ventricular end-diastolic and end-systolic diameters, and left ventricular mass ( Table 2 ). In a multivariate linear regression analysis, age (β = −0.53, P < .001), diastolic blood pressure (β = 0.025, P = .04), aortic root diameter (β = −0.289, P < .001), left atrial diameter (β = 0.133, P < .001), left ventricular end-diastolic volume (β = 0.154, P = .003), and left ventricular mass (β = 0.009, P = .09) explained only 7% of PASP variability. The larger contributor to PASP variability was left atrial dimension, with a partial R 2 value of 2.8%, followed by left ventricular end-diastolic diameter (partial R 2 = 1.8%) and age (partial R 2 = 1.4%). Repeating the analysis with the addition of BMI and shortening fraction, which were previously reported to contribute to the prediction of PASP variability, did not significantly add to the explained variance.

Table 2

Correlations between PASP and patient characteristics

Variable Correlation coefficient 95% confidence interval P
Age −0.154 −0.197 to −0.109 <.0001
Body surface area 0.026 −0.019 to 0.071 .26
Blood pressure
Systolic 0.030 −0.016 to 0.077 .20
Diastolic 0.051 0.004 to 0.097 .03
Heart rate 0.023 −0.024 to 0.070 .33
Echocardiographic parameters
Aortic root −0.093 −0.137 to −0.048 <.0001
Left atrial diameter 0.171 0.127 to 0.214 <.0001
Left ventricular end-diastolic diameter 0.142 0.098 to 0.186 <.0001
Left ventricular end-systolic diameter 0.094 0.050 to 0.139 <.0001
Septum 0.030 −0.015 to 0.074 .19
Posterior wall 0.053 0.008 to 0.097 .0218
Left ventricular mass 0.124 0.080 to 0.168 <.0001
Shortening fraction −0.009 −0.054 to 0.036 .7

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Jun 11, 2018 | Posted by in CARDIOLOGY | Comments Off on Pulmonary Artery Pressure in Young Healthy Subjects
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