Exercise cardiac MRI unmasks right ventricular dysfunction in acute hypoxia and chronic pulmonary arterial hypertension

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Title: Exercise cardiac MRI unmasks right ventricular dysfunction in acute hypoxia and chronic pulmonary arterial hypertension
Authors: Jaijee, SK
Quinlan, M
Tokarczuk, P
Clemence, M
Howard, L
Gibbs, JSR
O'Regan, DP
Item Type: Journal Article
Abstract: Background - Coupling of right ventricular (RV) contractility to afterload is maintained at rest in the early stages of pulmonary arterial hypertension (PAH), but exercise may unmask depleted contractile reserves. We assessed whether elevated afterload reduces RV contractile reserve despite compensated resting function using non-invasive exercise imaging. Methods and Results - Fourteen patients with PAH (mean age 39.1 years, 10 females) and 34 healthy control subjects (mean age 35.6 years, 17 females) completed real-time cardiac magnetic resonance imaging during sub-maximal exercise breathing room-air. Controls were then also exercised during acute normobaric hypoxia (FiO2 12%). RV contractile reserve was assessed by the effect of exercise on ejection fraction (RVEF). In control subjects the increase in RVEF on exercise was less during hypoxia (P=0.017), but the response of left ventricular ejection fraction to exercise did not change. Patients with PAH had impaired RV reserve with half demonstrating a fall in RVEF on exercise despite comparable resting function to controls (PAH: rest 53.6{plus minus}4.3% vs exercise 51.4{plus minus}10.7%; controls: rest 57.1{plus minus}5.2% vs exercise 69.6{plus minus}6.1%, P<0.0001). In control subjects the increase in stroke volume index (SVi) on exercise was driven by reduced RV end-systolic volume, whereas PAH patients did not augment SVi, with increases in both end-diastolic and end-systolic volumes. From baseline hemodynamic and exercise capacity variables only VE/VCO2 was an independent predictor of RV functional reserve (P=0.021). Conclusions - Non-invasive cardiac imaging during exercise unmasks depleted RV contractile reserves in healthy adults under hypoxic conditions and PAH patients under normoxic conditions despite preserved ejection fraction.
Issue Date: 18-May-2018
Date of Acceptance: 14-May-2018
ISSN: 1522-1539
Publisher: American Physiological Society
Journal / Book Title: AJP - Heart and Circulatory Physiology
Copyright Statement: © 2018, American Journal of Physiology-Heart and Circulatory Physiology. AAM available online open access under a CC-BY licence (
Sponsor/Funder: British Heart Foundation
Imperial College Healthcare NHS Trust- BRC Funding
Imperial College Healthcare NHS Trust- BRC Funding
Funder's Grant Number: PG/13/44/30321
Keywords: Exercise testing
Magnetic Resonance Imaging
Pulmonary Hypertension
0606 Physiology
1116 Medical Physiology
Cardiovascular System & Hematology
Publication Status: Published online
Online Publication Date: 2018-05-18
Appears in Collections:Clinical Sciences
Imaging Sciences
National Heart and Lung Institute
Faculty of Medicine

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