What is the clinical evidence from this study?

Study design: Case Report. Population: Atherosclerotic right coronary artery (n=1). Intervention: Wall pressure and wall pressure gradient. Primary outcome: Correlation between slice-averaged wall thickness and wall pressure under mean pressure (r = -0.81, p=<0.0001).

January 1, 2012Open Access

Correlations of coronary plaque wall thickness with wall pressure and wall pressure gradient: a representative case study

Q: What are the key findings of this study?

Wall pressure correlated negatively with plaque wall thickness (r = -0.81), while wall pressure gradient correlated positively with wall thickness (r = 0.45) in a human atherosclerotic right coronary artery.

BLBiyue LiuMonmouth University JZJie ZhengMallinckrodt (United States)RBRichard G. BachInterventional Cardiology

Key Result

Wall pressure correlated negatively with plaque wall thickness (r = -0.81), while wall pressure gradient correlated positively with wall thickness (r = 0.45) in a human atherosclerotic right coronary artery.

Study Design

Type

Case Report (n=1)

Structured PICO

Population

1 patient with an atherosclerotic right coronary artery whose intravascular ultrasound data was used to model correlations between wall thickness and hemodynamic stresses.

Exposure

Computational fluid dynamics simulation of pulsatile blood flow using a three-dimensional mathematical model.

Outcome

Correlation of wall thickness (WT) with wall pressure (WP) and spatial wall pressure gradient (WPG).surrogate

In a patient-specific computational model, coronary plaque wall thickness correlated negatively with wall pressure and positively with wall pressure gradient, suggesting local blood pressure hemodynamics may play a role in plaque progression.

Main Result

Effect estimate: r = -0.81

p-value: p=<0.0001

Limitations

Image data and boundary conditions are from different patients.
Vessel curvature was based on a single plane (2D) angiographic data which is only an approximation to the actual 3D curvature.
Plaque material properties from the current literature were used since patient-specific data was not available.
The analysis might not reveal strong correlations of the wall thickness with wall pressure and wall pressure gradient in situations where wall thickness variation is notable but there is not yet a stenosis that affects the lumen.

Abstract

BACKGROUND: There are two major hemodynamic stresses imposed at the blood arterial wall interface by flowing blood: the wall shear stress (WSS) acting tangentially to the wall, and the wall pressure (WP) acting normally to the wall. The role of flow wall shear stress in atherosclerosis progression has been under intensive investigation, while the impact of blood pressure on plaque progression has been under-studied. METHOD: The correlations of wall thickness (WT) with wall pressure (WP, blood pressure on the lumen wall) and spatial wall pressure gradient (WPG) in a human atherosclerotic right coronary artery were studied. The pulsatile blood flow was simulated using a three dimensional mathematical model. The blood was treated as an incompressible viscous non-Newtonian fluid. The geometry of the artery was re-constructed using an in vivo intravascular ultrasound (IVUS) 44-slice dataset obtained from a patient with consent obtained. The WT, the WP and the WPG were averaged on each slice, respectively, and Pearson correlation analysis was performed on slice averaged base. Each slice was then divided into 8 segments and averaged vessel WT, WP and WPG were collected from all 352 segments for correlation analysis. Each slice was also divided into 2 segments (inner semi-wall of bend and outer semi-wall of bend) and the correlation analysis was performed on the 88 segments. RESULTS: Under mean pressure, the Pearson coefficient for correlation between WT and WP was r = - 0.52 (p < 0.0001) by 2-segment analysis and r = - 0.81 (p < 0.0001) by slice averaged analysis, respectively. The Pearson coefficient for correlation between WT and WPG was r = 0.30 (p = 0.004) by 2-segment analysis and r = 0.45 (p = 0.002) by slice averaged analysis, respectively. The r-values corresponding to systole and diastole pressure conditions were similar. CONCLUSIONS: Results from this representative case report indicated that plaque wall thickness correlated negatively with wall pressure (r = -0.81 by slice) and positively with wall pressure gradient (r = 0.45). The slice averaged WT has a strong linear relationship with the slice averaged WP. Large-scale patient studies are needed to further confirm our findings.

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