Author + information
- Received June 26, 2019
- Revision received October 15, 2019
- Accepted November 15, 2019
- Published online July 6, 2020.
- Petter Storsten, MDa,b,c,
- John M. Aalen, MDa,b,c,
- Espen Boe, MD, PhDa,b,
- Espen W. Remme, MSc, Dr.inga,c,
- Ola Gjesdal, MD, PhDb,
- Camilla Kjellstad Larsen, MDa,b,c,
- Øyvind Senstad Andersen, MDa,b,c,
- Morten Eriksen, MD, PhDa,c,
- Erik Kongsgaard, MD, PhDb,c,
- Jürgen Duchenne, MSc, PhDd,e,
- Jens-Uwe Voigt, MD, PhDd,e,
- Otto A. Smiseth, MD, PhDa,b,c,f and
- Helge Skulstad, MD, PhDa,b,c,f,∗ ()
- aInstitute for Surgical Research, Oslo University Hospital, Rikshospitalet, Oslo, Norway
- bDepartment of Cardiology, Oslo University Hospital, Rikshospitalet, Oslo, Norway
- cCenter for Cardiological Innovation, Oslo University Hospital, Rikshospitalet, Oslo, Norway
- dDepartment of Cardiovascular Sciences, KU Leuven - University of Leuven, Leuven, Belgium
- eDepartment of Cardiovascular Diseases, University Hospitals Leuven, Leuven, Belgium
- fInstitute of Clinical Medicine, Faculty of Medicine, University of Oslo, Oslo, Norway
- ↵∗Address for correspondence:
Dr. Helge Skulstad, Department of Cardiology, Rikshospitalet, Oslo University Hospital, P.O. Box 4950 Nydalen, N-0424 Oslo, Norway.
Objectives The purpose of this study was to investigate how LBBB and CRT modify RV free wall function by direct ventricular interaction.
Background Right ventricular (RV) function influences prognosis in patients with left bundle branch block (LBBB) and cardiac resynchronization therapy (CRT). There is, however, limited insight into how LBBB and CRT affect RV function.
Methods In 24 patients with LBBB with nonischemic cardiomyopathy, RV and left ventricular (LV) strain by speckle-tracking echocardiography was measured before and after CRT. Underlying mechanisms were studied in 16 anesthetized dogs with ultrasonic dimension crystals and micromanometers.
Results Patients with LBBB demonstrated distinct early systolic shortening in the RV free wall, which coincided with the typical abnormal early systolic septal shortening. In animals, this RV free wall contraction pattern resulted in reduced myocardial work as a large portion of the shortening occurred against low pressure during early systole, coinciding with abnormal leftward septal motion. RV systolic function was maintained by vigorous contraction in the late-activated LV lateral wall, which pushed the septum toward the RV. CRT reduced abnormal septal motion and increased RV free wall work because there was less inefficient shortening against low pressure.
Conclusions LBBB reduces workload on the RV free wall because of abnormal septal motion and delayed activation of the LV lateral wall. Restoring septal and LV function by CRT increases workload in RV free wall and may explain why patients with RV failure respond poorly to CRT. (Contractile Reserve in Dyssynchrony: A Novel Principle to Identify Candidates for Cardiac Resynchronization Therapy [CRID-CRT]; NCT02525185)
- cardiac resynchronization therapy
- heart failure
- left bundle branch block
- myocardial work
- right ventricle
- septal flash
Drs. Storsten, Larsen, and Andersen were recipients of clinical research fellowships from the South-Eastern Norway Regional Health Authority. Drs. Aalen and Boe were supported by grants from the Norwegian Health Association. Dr. Voigt holds a personal research mandate of the Research Foundation-Flanders (FWO). Dr. Voigt and Mr. Duchenne were supported by a grant of the University of Leuven. All other authors have reported that they have no relationships relevant to the contents of this paper to disclose.
The authors attest they are in compliance with human studies committees and animal welfare regulations of the authors' institutions and Food and Drug Administration guidelines, including patient consent where appropriate. For more information, visit the JACC: Cardiovascular Imaging author instructions page.
- Received June 26, 2019.
- Revision received October 15, 2019.
- Accepted November 15, 2019.
- 2020 American College of Cardiology Foundation
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