What is the clinical evidence from this study?

Study design: Other. Population: Hypertension (n=24). Intervention: Nifedipine vs. Saline. Primary outcome: Ratio of area with Oscillatory Shear Index (OSI) > 0.2.

May 10, 2017Open Access

Vascular Remodelling Relates to an Elevated Oscillatory Shear Index and Relative Residence Time in Spontaneously Hypertensive Rats

Key Result

In spontaneously hypertensive rats, blood pressure normalization with nifedipine failed to attenuate elevated oscillatory shear index and relative residence time, which remained correlated with vascular wall thickening.

Structured PICO

Does nifedipine improve haemodynamic parameters (OSI and RRT) in spontaneously hypertensive rats?

Population

24 adult male spontaneously hypertensive rats and normotensive Wistar-Kyoto rats were treated for 7 days to observe hemodynamic characteristics and vascular remodeling.

Intervention

Nifedipine 50 mg/kg/day by gavage bid for 7 days

Comparator

0.9% saline for 7 days

Outcome

Haemodynamic parameters including oscillatory shear index (OSI) and relative residence time (RRT) obtained via aortic computational fluid dynamics (CFD) modelssurrogate

Normalizing blood pressure with nifedipine in hypertensive rats does not reverse disturbed aortic hemodynamics (elevated OSI and RRT), which correlate with persistent vascular structural remodeling.

Main Result

Absolute Event Rate: 6.09% vs 6.98%

Limitations

Lack of accurate data for the blood viscosity in 8-month-old SHRs and WKYs, requiring the use of a commonly used estimated value.
Did not test the relationship among elevated OSI, increased RRT, and the changes of arterial wall thickness over time.
Used computational fluid dynamics (CFD) models which do not account for fluid-solid interaction (FSI) during simulation.

Abstract

Haemodynamic disorders are common clinical findings in hypertension and lead to adverse cardiovascular events. However, the haemodynamic conditions in hypertension models are poorly understood. This study aimed to observe the characteristics of haemodynamics in spontaneously hypertensive rats (SHRs) and antihypertensive-treated SHRs. Twenty-four adult male SHRs and Wistar-Kyoto rats (WKYs) were randomly divided into four groups and treated for 7 days as follows: WKY-CON (WKYs + saline), WKY-NIF (WKYs + nifedipine, 50 mg/kg/day), SHR-CON (SHRs + saline), and SHR-NIF (SHRs + nifedipine). Aortic computational fluid dynamics (CFD) models were simulated to obtain the haemodynamic parameters. We found that in the hypertensive (SHR-CON) and blood pressure-controlled (SHR-NIF) groups, the oscillatory shear index (OSI) and relative residence time (RRT), which are key haemodynamics indices, were markedly elevated. Furthermore, there was a correlation between both the elevated OSI and RRT with the vascular wall thickening in regions near the inner wall of the aortic arch. Our research demonstrates that haemodynamics remains disturbed even if the blood pressure is normalized. In addition, vascular remodelling may play an important role in maintaining elevated OSI and RRT values.

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