Clinical Research
Pulmonary Hypertension
Interventricular Mechanical Asynchrony in Pulmonary Arterial Hypertension: Left-to-Right Delay in Peak Shortening Is Related to Right Ventricular Overload and Left Ventricular Underfilling

https://doi.org/10.1016/j.jacc.2007.10.041Get rights and content
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Objectives

The purpose of this study was to explore in pulmonary arterial hypertension (PAH) whether the cause of interventricular asynchrony lies in onset of shortening or duration of shortening.

Background

In PAH, leftward ventricular septal bowing (LVSB) is probably caused by a left-to-right (L-R) delay in myocardial shortening.

Methods

In 21 PAH patients (mean pulmonary arterial pressure 55 ± 13 mm Hg and electrocardiogram–QRS width 100 ± 16 ms), magnetic resonance imaging myocardial tagging (14 ms temporal resolution) was applied. For the left ventricular (LV) free wall, septum, and right ventricular (RV) free wall, the onset time (Tonset) and peak time (Tpeak) of circumferential shortening were calculated. The RV wall tension was estimated by the Laplace law.

Results

The Tonset was 51 ± 23 ms, 65 ± 4 ms, and 52 ± 22 ms for LV, septum, and RV, respectively. The Tpeak was 293 ± 58 ms, 267 ± 22 ms, and 387 ± 50 ms for LV, septum, and RV, respectively. Maximum LVSB was at 395 ± 45 ms, coinciding with septal overstretch and RV Tpeak. The L-R delay in Tonset was −1 ± 16 ms (p = 0.84), and the L-R delay in Tpeak was 94 ± 41 ms (p < 0.001). The L-R delay in Tpeak was not related to the QRS width but was associated with RV wall tension (p < 0.05). The L-R delay in Tpeak correlated with leftward septal curvature (p < 0.05) and correlated negatively with LV end-diastolic volume (p < 0.05) and stroke volume (p < 0.05).

Conclusions

In PAH, the L-R delay in myocardial peak shortening is caused by lengthening of the duration of RV shortening. This L-R delay is related to LVSB, decreased LV filling, and decreased stroke volume.

Abbreviations and Acronyms

BSA
body surface area
ECG
electrocardiogram
EDV
end-diastolic volume
L-R delay
left-to-right ventricular delay in circumferential shortening
LV
left ventricle/ventricular
LVSB
leftward ventricular septal bowing
MRI
magnetic resonance imaging
PAH
pulmonary arterial hypertension
PAP
pulmonary arterial pressure
RBBB
right bundle branch block
RV
right ventricle/ventricular
Tonset
time to onset of circumferential shortening
Tpeak
time to peak of circumferential shortening

Cited by (0)

1

C.T. Gan was financially supported by the Netherlands Organisation for Scientific Research (NWO), Mozaiek Grant, project number 017.001.154.

2

Dr. Zwanenburg was financially supported by the Netherlands Heart Foundation, grant number NHF-2000B220.