Chest
Volume 140, Issue 1, July 2011, Pages 27-33
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Original Research
Pulmonary Vascular Disease
Longitudinal Shortening Accounts for the Majority of Right Ventricular Contraction and Improves After Pulmonary Vasodilator Therapy in Normal Subjects and Patients With Pulmonary Arterial Hypertension

https://doi.org/10.1378/chest.10-1136Get rights and content

Background

The right ventricle has a unique contraction pattern, with a greater portion of the shortening occurring in the longitudinal plane. However, the relative contributions of longitudinal and transverse shortening to overall right ventricular (RV) function have not been quantified. We sought to quantify the proportions of longitudinal and transverse shortening to RV function in normal subjects and in patients with pulmonary arterial hypertension (PAH) at baseline and following PAH-specific therapy.

Methods

The normal cohort comprised 90 subjects with normal clinical echocardiograms, whereas the PAH cohort included 36 patients, of whom 25 had echocardiograms before and after initiation of PAH-specific therapy. Assessment of RV function included tricuspid annular plane systolic excursion, RV fractional area change (RVFAC), and relative change in RV area in longitudinal and transverse planes.

Results

Longitudinal fractional area change (LFAC) accounted for the majority of total RVFAC (77% ± 14%) in normal subjects. Among patients with PAH, longitudinal shortening still represented the majority of RVFAC, even though it was less than in normal subjects (63% ± 18%, P < .0001). Following PAH therapy, overall RV function improved (RVFAC, 30% ± 13% to 36% ± 9%; P = .026), solely because of an increase in longitudinal area change. As a result, the proportion of longitudinal shortening increased (LFAC, 58% ± 18% to 69% ± 17%; P = .002), whereas transverse shortening fell (transverse fractional area change, 42% ± 18% vs 31% ± 17%; P = .002).

Conclusions

Longitudinal shortening accounts for the majority of RV contraction in normal subjects and patients with PAH, although less so in PAH. Improved RV function following pulmonary vasodilator therapy occurs solely from improvements in longitudinal contraction, suggesting that longitudinal shortening may represent the afterload-responsive element of RV functional recovery.

Section snippets

Normal Subjects

All clinically indicated echocardiograms obtained at the Hospital of the University of Pennsylvania over a 2-month period in 2006 were screened. Those deemed normal by the clinical reviewer were selected and analyzed retrospectively by the research investigator. Inclusion criteria were designed to capture normal adult echocardiograms and included the following: (1) age 18 years or older; (2) normal left atrial and ventricular size using standard criteria; (3) normal left ventricular (LV)

Results

We identified 90 subjects with normal echocardiograms and 36 subjects with PAH with baseline echocardiograms who met the criteria for inclusion in this study. The causes of PAH included connective tissue disease (systemic sclerosis in 15 patients, systemic lupus erythematosus in two patients), idiopathic PAH (in 14 patients), portopulmonary hypertension (in two patients), and chronic thromboembolic disease (in three patients). The two groups were similar with regard to gender (normal subjects:

Discussion

To the best of our knowledge, our study is the first to quantify the degree to which longitudinal contraction contributes to overall RV function. We found that, in the presence of increased RV afterload in PAH, longitudinal contraction is selectively impaired and the improvement in RV function after pulmonary vasodilating therapy is due to a recovery in longitudinal contraction. There was no improvement in transverse contraction with pulmonary vasodilators, suggesting that longitudinal

Conclusions

Longitudinal motion accounts for the majority of overall RV function in normal subjects and in patients with PAH. The RV dysfunction seen in PAH is characterized by more prominent impairment of longitudinal, than of transverse, motion. Treatment with PH-specific therapy leads to selective recovery of longitudinal RV motion. These findings provide further rationale for the use of longitudinal measures of RV function and suggest that serial monitoring of such measures may play an important role

Acknowledgments

Author contributions: The authors all assume responsibility for the integrity of the data.

Dr Brown: contributed to the original design and conception of the study, data acquisition, data analysis, and preparation and critical review of the manuscript.

Dr Raina: contributed to the study design, data acquisition, data analysis, and preparation and critical review of the manuscript.

Dr Katz: contributed to the design and conception of the study, data acquisition, data analysis, and preparation of

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    Funding/Support: The authors have reported to CHEST that no funding was received for this study.

    Reproduction of this article is prohibited without written permission from the American College of Chest Physicians (http://www.chestpubs.org/site/misc/reprints.xhtml).

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