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Evaluation of Coronary Flow Reserve After Myocardial Ischemia Reperfusion in Rats
Published on: June 28, 2019
Continuous Thermodilution Method to Assess Coronary Flow Reserve
Alejandro Gutiérrez-Barrios1, Elena Izaga-Torralba2, Fernando Rivero Crespo3
1Cardiology Department, Hospital Puerta del Mar, Cádiz, Spain; Instituto de Investigación e Innovación en Ciencias Biomédicas de Cádiz, INiBICA, Spain.
Insights
Continuous thermodilution effectively quantifies resting absolute coronary flow (AF) and coronary flow reserve (CFR) in patients. This novel method, CFRThermo-infusion, correlates well with the established CFRthermo-bolus technique.
Area of Science:
- Cardiology
- Physiology
- Medical Devices
Background:
- Coronary flow reserve (CFR) is crucial for clinical risk stratification.
- Invasive CFR assessment traditionally uses Doppler or thermodilution with saline boluses (CFRthermo-bolus).
- Continuous thermodilution offers a novel, operator-independent method for quantifying absolute coronary flow (AF).
Purpose of the Study:
- To evaluate the feasibility of continuous thermodilution for quantifying resting AF.
- To determine CFR using continuous thermodilution (CFRThermo-infusion).
- To compare CFRThermo-infusion with CFRthermo-bolus.
Main Methods:
- Sixty-two patients with suspected coronary disease underwent invasive assessment.
- Absolute coronary flow (AF) was measured at maximal hyperemia (20 mL/min) and varying infusion rates (6-12 mL/min) using a dedicated catheter and temperature/pressure guidewire.
- Resting AF was determined at 10 mL/min infusion, and hyperemic AF at 20 mL/min; CFRThermo-infusion was calculated as their ratio.
Main Results:
- Continuous thermodilution confirmed hyperemia at 12 mL/min infusion, with adequate curve tracings at 10 mL/min for resting AF assessment.
- Mean CFRThermo-infusion was 2.56 ± 0.9, closely correlating with CFRthermo-bolus (2.49 ± 1; r=0.76, p<0.001).
- High intraclass agreement (ICC=0.76, p<0.001) was observed between the two CFR measurement methods.
Conclusions:
- Continuous thermodilution is a feasible method for quantifying resting absolute coronary flow.
- This technique provides a novel clinical tool for determining coronary flow reserve.
- CFRThermo-infusion demonstrates good correlation and agreement with the established CFRthermo-bolus method.
Abstract:
Coronary flow reserve (CFR) is a well-validated flow-based physiological parameter that has shown value in clinical risk stratification. CFR can be invasively assessed, classically by Doppler and, more recently, by thermodilution with saline boluses (CFRthermo-bolus). Alternatively, continuous thermodilution is a novel operator-independent, highly-reproducible technique to invasively quantify maximum absolute coronary flow (AF). This study aimed to assess the feasibility of this method to quantify resting AF and to determine CFR (CFRThermo-infusion) as compared with CFRthermo-bolus. Sixty-two consecutive patients with suspicion of coronary disease and absence of significant epicardial lesions were prospectively investigated. AF at maximal hyperemia (20 mL/min) and at lower infusion rates (6-8-10-12 mL/min) were systematically measured using a dedicated catheter and a temperature/pressure guidewire. The absence of baseline Pd/Pa decrease at 6 (0.15 ± 0.2%), 8 (0.17 ± 0.18%) and 10 mL/min (0.2 ± 0.12%) demonstrated absence of hyperemia at ≤10 mL/min (all p = NS). However, at 12 mL/min hyperemia was confirmed by a significant decrease in Pd/Pa (1.3 ± 1.5%, p <0.01) and increase in AF from 10 mL/min to 12 mL/min (31.4 ± 28.1 mL, p <0.05). All curve tracings at 10 mL/min (129/129, 100%) were adequate versus only (7/15, 53%) and (15/18, 17%) at 6 mL/min, and 8 mL/min, respectively, and this infusion-rate was considered to determine resting-AF. CFRThermo-infusion was determined as the ratio of hyperemic-AF (20 mL/min) by resting-AF (10 mL/min). Mean CFRThermo-infusion was 2.56 ± 0.9 and CFRthermo-bolus 2.49 ± 1. Both parameters showed a good correlation (r = 0.76; p <0.001) and intraclass agreement (ICC = 0.76; p <0.001).The continuous thermodilution method enables to quantify resting-AF providing a novel clinical tool to determine CRF. CFRThermo-infusion shows a good correlation with CFRthermo-bolus..
