Investigation of Left Ventricular Strain and Its Morphological Basis During Different Stages of Diastolic and Systolic Dysfunction in Spontaneously Hypertensive Rat

Liyun Fu; Qinyun Ruan; Ziling You; Huimei Huang; Yupeng Chen; Sheng Cheng; Lei Yan; Huang'e Cai; Yali Chen; Dongmei Lin; Huizhen Chen; Chunyan Huang

doi:10.1093/ajh/hpac008

Investigation of Left Ventricular Strain and Its Morphological Basis During Different Stages of Diastolic and Systolic Dysfunction in Spontaneously Hypertensive Rat

Am J Hypertens. 2022 May 10;35(5):423-432. doi: 10.1093/ajh/hpac008.

Authors

Affiliations

¹ Department of Ultrasound, The First Affiliated Hospital of Fujian Medical University, Fuzhou, China.
² Department of Pathology, The First Affiliated Hospital of Fujian Medical University, Fuzhou, China.

PMID: 35089307
DOI: 10.1093/ajh/hpac008

Abstract

Background: Myocardial fibrosis plays an important role in the pathogenesis of hypertensive cardiac dysfunction, and myocardial strain could detect early systolic abnormalities when left ventricular ejection fraction (LVEF) is preserved. The aim of this study was to investigate the characteristics of left ventricular multidirectional strain during different stages of heart dysfunction and the possible morphological basis in spontaneously hypertensive rats (SHRs).

Methods: SHRs and Wistar-Kyoto (WKY) rats were randomly divided into cages and observed for 3-25 months. Echocardiographic measurements, LV + dp/dtmax and left ventricular end-diastolic pressure (LVEDP), and histological collagen volume fraction (CVF) were observed in all rats.

Results: According to LVEF and LVEDP, SHRs were divided into normal cardiac function group (group A), diastolic dysfunction group (group B1), and systolic dysfunction group (group B2). In group A, myocardial strain and CVF showed no difference compared with the control group. In group B1, global longitudinal strain (GLS) and endocardial longitudinal strain (SL-endo) were lower than those in group A CVF-endo was increased (all P < 0.05). In group B2, global and layer-specific strain decreased significantly, along with the increased CVF-endo and CVF-epi (all P < 0.05). The decrease of GLS and SL-endo was moderately correlated with the increase of CVF-endo. The reduction of LVEF was correlated with the decrease of SC-endo (r = 0.65, P < 0.01).

Conclusions: Pathological myocardial fibrosis associated with hypertension develops from the inner to outer layer of myocardium, which is coincident with the impairment of myocardial deformation, where longitudinal strain is involved firstly and LVEF declines when all directions of strain are reduced.

Keywords: blood pressure; echocardiography; hypertension; myocardial fibrosis; rats; strain.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Animals
Cardiomyopathies*
Fibrosis
Hypertension* / complications
Rats
Rats, Inbred SHR
Rats, Inbred WKY
Stroke Volume
Ventricular Dysfunction, Left* / diagnostic imaging
Ventricular Dysfunction, Left* / etiology
Ventricular Function, Left