Abstract
This study sought to examine layer-specific longitudinal and circumferential systolic and diastolic strain, strain rate (SR) and diastolic time intervals in hypertensive patients with and without diastolic dysfunction. Fifty-eight treated hypertensive patients were assigned to normal diastolic function (NDF, N = 39) or mild diastolic dysfunction (DD, N = 19) group. Layer-specific systolic and diastolic longitudinal and circumferential strains and SR were assessed. Results showed no between-group difference in left ventricular mass index (DD: 92.1 ± 18.1 vs NDF: 88.4 ± 16.3; P = 0.44). Patients with DD had a proportional reduction in longitudinal strain across the myocardium (endocardial for DD −13 ± 4%; vs NDF −17 ± 3, P < 0.01; epicardial for DD −10 ± 3% vs NDF −13 ± 3%, P < 0.01; global for DD: −12 ± 3% vs NDF: −15 ± 3, P = 0.01), and longitudinal mechanical diastolic impairments as evidenced by reduced longitudinal strain rate of early diastole (DD 0.7 ± 0.2 L/s vs NDF 1.0 ± 0.3 L/s, P < 0.01) and absence of a transmural gradient in the duration of diastolic strain (DD endocardial: 547 ± 105 ms vs epicardial: 542 ± 113 ms, P = 0.24; NDF endocardial: 566 ± 86 ms vs epicardial: 553 ± 77 ms, P = 0.03). Patients with DD also demonstrate a longer duration of early circumferential diastolic strain (231 ± 71 ms vs 189 ± 58 ms, P = 0.02). In conclusion, hypertensive patients with mild DD demonstrate a proportional reduction in longitudinal strain across the myocardium, as well as longitudinal mechanical diastolic impairment, and prolonging duration of circumferential mechanical relaxation.
Highlights
Chronic exposure to elevated afterload is associated with maladaptive left ventricular (LV) remodeling, which involves myocardial hypertrophy, collagen deposition and interstitial fibrosis, resulting in cardiac dysfunction (1, 2)
Hypertensive patients with normal diastolic function (NDF) were younger than patients with DD
The key findings of this study are: (1) absolute peak longitudinal ε is proportionally reduced across the myocardium in patients with mild DD resulting in a maintained transmural gradient, (2) patients with mild DD exhibit longitudinal diastolic mechanical impairments, as evidenced by reduced longitudinal SRE and absence of longitudinal transmural gradient in the duration of overall diastolic ε and (3) duration of circumferential diastolic ε is prolonged in patients with DD as a potential compensatory mechanism for the longitudinal diastolic impairments
Summary
Chronic exposure to elevated afterload is associated with maladaptive left ventricular (LV) remodeling, which involves myocardial hypertrophy, collagen deposition and interstitial fibrosis, resulting in cardiac dysfunction (1, 2). Two-dimensional (2D) strain (ε) imaging can be employed to detect regional and global myocardial abnormalities not recognized by conventional echocardiography. Impaired systolic and diastolic (ε) has been reported in patients with hypertension (3, 4). Global ε does not provide a comprehensive evaluation of LV mechanics, as it only measures global function and not myocardial layer-specific activity. The endocardium is the most susceptible layer to the early deleterious effects of hypertension, as the disease progresses, the pathology proliferates resulting in gradual deterioration of mid-myocardial and epicardial activity as well (5). Different stages of hypertension may result in layer-specific dysfunction that cannot be detected from single-layer assessment
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