|ESCR 2016 / P-0024||
|Quantitative myocardial perfusion measured before and after invasive treatment using advanced CT-technology|
Methods and Materials
The study was prospectively conducted to evaluate myocardial blood flow (MBF) before and after surgery in patients with indication for coronary dilatation/stenting, coronary bypass surgery or aortic valve replacement.
All CT studies were performed with ECG-gating triggered at 40 % of the R-R-interval, i. v. contrast agent with a concentration of 210 mgIodine/ml and 80, 100 or 120 KV (Rienmüller et al. 2013) depending on the patient’s weight using a 256 row volume CT. The images were acquired every heart beat and reconstructed with a slice thickness of 5 mm using a cardaic smooth convolution kernel (CA) and an iterative reconstruction algorithm.
The images were motion corrected (Janssens et al. 2011) and the left ventricular myocardium was segmented using a 3D semi-automatic modular workflow (compare Rienmüller et al. 2013). MBF was calculated based on the contrast enhancement time curves obtained from a region of interest (ROI) placed in the left ventricle (input function) and the segmented myocardial region (output function, see Fig. 1) using the maximum slope of the fitted model curves (Chan et al. 2003) of the entire volume applying a modified version of the upslope method (Baumgartner 1998).
Additionally, we acquired heart rate (HR), systolic and diastolic blood pressure (SBP/DBP) and computed the rate pressure product (RPP), the product of heart rate and systolic blood pressure (RPP=HR*SBP), since basal myocardial blood flow is closely related to the RPP and the RPP represents an indicator for myocardial oxygen consumption (Uren et al. 1994).
Ventricular parameters comprised the left ventricular muscle mass (LVMM), the cardiac output (CO), and the end diastolic volume (EDV), since these parameters are known to be affected by aortic insufficiency (see e.g. Osbakken et al. 1981) and serve as an indicator for the outcome of the surgical treatment.
All patients with angiographic indication for one of the invasive therapies were included in the study provided they agreed to the examination by informed written consent (study registered at Gov.Trial NCT02361996).
Until now, the patient cohort comprises 12 patients, two female and 10 male, with a mean age of 64±11.0 (range 44-78) years, a weight of 80.8±14.2 (65-108) kg. The BMI was 28.4±28.7 (23.1-33.2) kg/m2 and the BSA 1.9±0.2 (23.1-33.2) m2 (see Fig. 2). 8 Patients underwent a coronary bypass surgery and 4 patients an aortic valve replacement.
Coronary Bypass Surgery Group:
8 patients, all male, age 62.4±8.7 (47-70) years, weight: 79.9±14.6 (66-108) kg, BMI: 26.9±3.4 (23.1-32.5) kg/m2, body surface area (BSA): 1.9±0.2 (1.76-2.33) m2. All patients suffered from at least one stenotic lesion above 85 %. The follow up eximantion of the patients took place 128±163 (7-358) days after surgery.
Aortic valve replacement group (without indication for coronary bypass surgery):
4 patients, 2 male, 2 female, age: 67±15.85 (44-78) years, weight: 82.2±15.3 (65-97) kg, BMI: 31.4±1.7 (29.9-33.2) kg/m2, BSA: 1.9±0.3 (1.59-2.2) m2. The patients did not show any significant (> 50%) stenotic lesion of the coronary arteries. The follow up eximantion of the patients took place 10±4 (7-14) days after surgery.
Unless otherwise specified, descriptive statistics are provided as mean±standard deviation and range for continuous variables. The Mann-Whitney-U-Test was used to compare parameter values before and after surgical treatment. A p-value < 0.05 was considered statistically significant. Pearson correlation coefficients were calculated for relationships between HR, RPP, SBP and MBF values. Statistical analysis was performed using Matlab2016a.
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