Afterload Hypersensitivity in Patients With Left Bundle Branch Block.
Aged
Animals
Arterial Pressure
Bundle-Branch Block
/ complications
Case-Control Studies
Disease Models, Animal
Dogs
Echocardiography, Doppler
Female
Heart Failure
/ diagnostic imaging
Humans
Hypertension
/ complications
Male
Middle Aged
Stroke Volume
Ventricular Dysfunction, Left
/ diagnostic imaging
Ventricular Function, Left
dyssynchrony
heart failure
hypertension
left bundle branch block
myocardial work
strain
Journal
JACC. Cardiovascular imaging
ISSN: 1876-7591
Titre abrégé: JACC Cardiovasc Imaging
Pays: United States
ID NLM: 101467978
Informations de publication
Date de publication:
06 2019
06 2019
Historique:
received:
31
08
2017
revised:
15
11
2017
accepted:
16
11
2017
pubmed:
24
1
2018
medline:
19
3
2020
entrez:
24
1
2018
Statut:
ppublish
Résumé
This study sought to investigate the hypothesis that patients with left bundle branch block (LBBB) are hypersensitive to elevated afterload. Epidemiological data suggest that LBBB can provoke heart failure in patients with hypertension. In 11 asymptomatic patients with isolated LBBB and 11 age-matched control subjects, left ventricular ejection fraction (LVEF) and global longitudinal strain (GLS) were measured by echocardiography. Systolic arterial pressure was increased by combining pneumatic extremity constrictors and handgrip exercise. To obtain more insight into mechanisms of afterload response, 8 anesthetized dogs with left ventricular (LV) micromanometer and dimension crystals were studied during acutely induced LBBB and aortic constriction. Regional myocardial work was assessed by LV pressure-dimension analysis. Consistent with normal afterload dependency, elevation of systolic arterial pressure by 38 ± 12 mm Hg moderately reduced LVEF from 60 ± 4% to 54 ± 6% (p < 0.01) in control subjects. In LBBB patients, however, a similar blood pressure increase caused substantially larger reduction in LVEF (p < 0.01), from 56 ± 6% to 42 ± 7% (p < 0.01). There were similar findings for GLS. In the dog model, aortic constriction abolished septal shortening (p < 0.02), and septal work decreased to negative values (p < 0.01). Therefore, during elevated systolic pressure, the septum made no contribution to global LV work, as indicated by net negative work, and instead absorbed energy from work done by the LV lateral wall. Moderate elevation of arterial pressure caused marked reductions in LVEF and GLS in patients with LBBB. This reflects a cardiodepressive effect of elevated afterload in the dyssynchronous ventricle and was attributed to loss of septal function.
Sections du résumé
OBJECTIVES
This study sought to investigate the hypothesis that patients with left bundle branch block (LBBB) are hypersensitive to elevated afterload.
BACKGROUND
Epidemiological data suggest that LBBB can provoke heart failure in patients with hypertension.
METHODS
In 11 asymptomatic patients with isolated LBBB and 11 age-matched control subjects, left ventricular ejection fraction (LVEF) and global longitudinal strain (GLS) were measured by echocardiography. Systolic arterial pressure was increased by combining pneumatic extremity constrictors and handgrip exercise. To obtain more insight into mechanisms of afterload response, 8 anesthetized dogs with left ventricular (LV) micromanometer and dimension crystals were studied during acutely induced LBBB and aortic constriction. Regional myocardial work was assessed by LV pressure-dimension analysis.
RESULTS
Consistent with normal afterload dependency, elevation of systolic arterial pressure by 38 ± 12 mm Hg moderately reduced LVEF from 60 ± 4% to 54 ± 6% (p < 0.01) in control subjects. In LBBB patients, however, a similar blood pressure increase caused substantially larger reduction in LVEF (p < 0.01), from 56 ± 6% to 42 ± 7% (p < 0.01). There were similar findings for GLS. In the dog model, aortic constriction abolished septal shortening (p < 0.02), and septal work decreased to negative values (p < 0.01). Therefore, during elevated systolic pressure, the septum made no contribution to global LV work, as indicated by net negative work, and instead absorbed energy from work done by the LV lateral wall.
CONCLUSIONS
Moderate elevation of arterial pressure caused marked reductions in LVEF and GLS in patients with LBBB. This reflects a cardiodepressive effect of elevated afterload in the dyssynchronous ventricle and was attributed to loss of septal function.
Identifiants
pubmed: 29361486
pii: S1936-878X(17)31144-0
doi: 10.1016/j.jcmg.2017.11.025
pii:
doi:
Types de publication
Journal Article
Research Support, Non-U.S. Gov't
Langues
eng
Sous-ensembles de citation
IM
Pagination
967-977Commentaires et corrections
Type : CommentIn
Informations de copyright
Copyright © 2019 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.