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Left atrial conduit flow rate at baseline and during exercise: an index of impaired relaxation in HFpEF patients

Marino, Paolo N., Zanaboni, Jacopo, Degiovanni, Anna, Sartori, Chiara, Patti, Giuseppe and Fraser, Alan G. 2021. Left atrial conduit flow rate at baseline and during exercise: an index of impaired relaxation in HFpEF patients. ESC Heart Failure 8 (5) , pp. 4334-4342. 10.1002/ehf2.13544

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Abstract

Aims In healthy subjects, adrenergic stimulation augments left ventricular (LV) long-axis shortening and lengthening, and increases left atrial (LA) to LV intracavitary pressure gradients in early diastole. Lower increments are observed in patients with heart failure with preserved ejection fraction (HFpEF). We hypothesized that exercise in HFpEF would further impair passive LV filling in early-mid diastole, during conduit flow from pulmonary veins. Methods and results Twenty HFpEF patients (67.8 ± 9.8 years; 11 women), diagnosed using 2007 ESC recommendations, underwent ramped semi-supine bicycle exercise to submaximal target heart rate (∼100 bpm) or symptoms. Seventeen asymptomatic subjects (64.3 ± 8.9 years; 7 women) were controls. Simultaneous LA and LV volumes were measured from pyramidal 3D-echocardiographic full-volume datasets acquired from an apical window at baseline and during stress, together with brachial arterial pressure. LA conduit flow was computed from the increase in LV volume from its minimum at end-systole to the last frame before atrial contraction (onset of the P wave), minus the reduction in LA volume during the same time interval; the difference was integrated and expressed as average flow rate, according to a published formula. The slope of single-beat preload recruitable stroke work (PRSW) quantified LV inotropic state. 3D LV torsion (rotation of the apex minus rotation of the base divided by LV length) was also measurable, both at rest and during stress, in 10 HFpEF patients and 4 controls. There were divergent responses in conduit flow rate, which increased by 40% during exercise in controls (+17.8 ± 37.3 mL/s) but decreased by 18% in patients with HFpEF (−9.6 ± 42.3 mL/s) (P = 0.046), along with congruent changes (+1.77 ± 1.13°/cm vs. −1.94 ± 2.73°/cm) in apical torsion (P = 0.032). Increments of conduit flow rate and apical torsion during stress correlated with changes in PRSW slope (P = 0.003 and P = 0.006, respectively). Conclusions In HFpEF, conduit flow rate decreases when diastolic dysfunction develops during exercise, in parallel with changes in LV inotropic state and torsion, contributing to impaired stroke volume reserve. Conduit flow is measurable using 3D-echocardiographic full-volume atrio-ventricular datasets, and as a marker of LV relaxation can contribute to the diagnosis of HFpEF.

Item Type: Article
Date Type: Publication
Status: Published
Schools: Medicine
Additional Information: This is an open access article under the terms of the Creative Commons Attribution-NonCommercial-NoDerivs License, which permits use and distribution in any medium, provided the original work is properly cited, the use is non-commercial and no modifications or adaptations are made.
Publisher: Wiley Open Access
ISSN: 2055-5822
Date of First Compliant Deposit: 23 September 2021
Date of Acceptance: 13 July 2021
Last Modified: 03 Nov 2021 13:59
URI: https://orca.cardiff.ac.uk/id/eprint/144392

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