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Changes in diastolic regional stiffness of the left ventricle before and after coronary artery bypass grafting
R Higashita1, M Sugawara, Y Kondoh
1Department of Cardiovascular Surgery, Cardiovascular Hospital of Central Japan, Gunma, Japan.
Insights
Coronary artery bypass grafting (CABG) improves left ventricular diastolic function. The stiffness constant, a new measure, significantly decreased in the CABG region post-surgery, indicating enhanced diastolic function.
Area of Science:
- Cardiology
- Biomedical Engineering
Background:
- Assessing left ventricular (LV) regional diastolic function is crucial for understanding heart disease.
- Coronary artery bypass grafting (CABG) aims to improve cardiac function in patients with coronary artery disease.
Purpose of the Study:
- To evaluate the impact of CABG on regional diastolic function of the left ventricular wall.
- To introduce and validate the use of a stiffness constant derived from the diastolic sigma-ln (1/H) relation for assessing diastolic function.
Main Methods:
- Applied the stiffness constant concept to the diastolic sigma-ln (1/H) relation (sigma = mean wall stress, H = regional wall thickness).
- Measured LV pressure and regional wall thickness in 12 cardiac regions of six patients before and after CABG.
- Calculated the stiffness constant (K) by fitting diastolic data points to sigma = Cexp[Kln (1/H)].
Main Results:
- Preoperatively, the stiffness constant was higher in the affected (CABG) region compared to the unaffected (non-CABG) region (4.79 +/- 2.56 vs 2.95 +/- 0.72).
- Postoperatively, the stiffness constant in the CABG region significantly decreased to 3.21 +/- 1.22.
- This decrease indicates an improvement in regional diastolic function after CABG.
Conclusions:
- The stiffness constant derived from the sigma-ln (1/H) relation is a valuable tool for assessing LV regional diastolic function.
- CABG surgery leads to a significant improvement in the diastolic properties of the left ventricular wall in the grafted region.
Abstract:
To evaluate the effect of coronary artery bypass grafting (CABG) on regional diastolic function of the left ventricular wall, we applied the concept of the stiffness constant to the diastolic sigma-ln (1/H) relation, where sigma is the mean wall stress, and H is the wall thickness of the region of concern, and ln (1/H) is the natural logarithm of the reciprocal of wall thickness. We assessed 12 cardiac regions in six patients with coronary artery disease who underwent CABG at the Cardiovascular Hospital of Central Japan between May 1994 and January 1995. Left ventricular pressure and regional wall thickness were measured simultaneously, with a micromanometer-tipped catheter and by two-dimensional echocardiography, respectively, before and after CABG. The stiffness constant (K) was obtained by fitting the diastolic sigma-ln (1/H) data points to an exponential curve with zero asymptote: sigma = Cexp[Kln (1/H)]. Preoperatively, the stiffness constant in the affected region (CABG region) was greater than that in the unaffected region (non-CABG region) (4.79 +/- 2.56 vs 2.95 +/- 0.72). Postoperatively, the stiffness constant in the CABG region was significantly decreased, to 3.21 +/- 1.22. The stiffness constant, which is derived from the sigma-ln (1/H) relation, is useful for the assessment of LV regional diastolic function.