Simplification of continuous intracoronary thermodilution.

Background: Continuous intracoronary thermodilution with saline allows for the accurate measurement of volumetric blood flow (Q) and absolute microvascular resistance (R). However, this requires repositioning of the temperature sensor by the operator to measure the entry temperature of the saline infusate, denoted as T.

Aims: We evaluated whether Ti could be predicted based on known parameters without compromising the accuracy of calculated Q.

Validation of resting full-cycle ratio and diastolic pressure ratio with [O]HO positron emission tomography myocardial perfusion.

Fractional flow reserve (FFR) and instantaneous wave-free ratio (iFR) are invasive techniques used to evaluate the hemodynamic significance of coronary artery stenosis. These methods have been validated through perfusion imaging and clinical trials. New invasive pressure ratios that do not require hyperemia have recently emerged, and it is essential to confirm their diagnostic efficacy.

Assessing the Impact of Prolonged Averaging of Coronary Continuous Thermodilution Traces.

Continuous Thermodilution is a novel method of quantifying coronary flow (Q) in mL/min. To account for variability of Q within the cardiac cycle, the trace is smoothened with a 2 s moving average filter. This can sometimes be ineffective due to significant heart rate variability, ventricular extrasystoles, and deep inspiration, resulting in a fluctuating temperature trace and ambiguity in the location of the "steady state".

Myocardial mass affects diagnostic performance of non-hyperemic pressure-derived indexes in the assessment of coronary stenosis.

Unlabelled: Background Several non-hyperemic pressure-derived Indexes (NHPI) have been introduced for the assessment of coronary stenosis, showing a good correlation with fractional flow reserve (FFR). Notably, either the assessment of NHPI during adenosine administration (NHPI) or the Hybrid Approach (NHPI), combining NHPI with FFR, have been showed to increase the accuracy of such indexes. It remains unclear whether diagnostic performance might be affected by the extent of the subtended myocardial mass.

Use of a Pressure Wire for Automatically Correcting Artifacts in Phasic Pressure Tracings From a Fluid-Filled Catheter.

Background/purpose: Matching phasic pressure tracings between a fluid-filled catheter and high-fidelity pressure wire has received limited attention, although each part contributes half of the information to clinical decisions. We aimed to study the impact of a novel and automated method for improving the phasic calibration of a fluid-filled catheter by accounting for its oscillatory behavior.

Methods/materials: Retrospective analysis of drift check tracings was performed using our algorithm that corrects for mean difference (offset), temporal delays (timing), differential sensitivity of the manifold transducer and pressure wire sensor (gain), and the oscillatory behavior of the fluid-filled catheter described by its resonant frequency and damping factor (how quickly oscillations disappear after a change in pressure).

Development, validation, and reproducibility of the pullback pressure gradient (PPG) derived from manual fractional flow reserve pullbacks.

Fractional flow reserve (FFR) pullbacks assess the location and magnitude of pressure drops along the coronary artery. The pullback pressure gradient (PPG) quantifies the FFR pullback curve and provides a numeric expression of focal versus diffuse coronary artery disease. This study aims (1) to validate the PPG using manual FFR pullbacks compared with motorized FFR pullbacks as a reference; and (2) to determine the intra- and interoperator reproducibility of the PPG derived from manual FFR pullbacks.

Validation of a novel non-hyperaemic index of coronary artery stenosis severity: the Resting Full-cycle Ratio (VALIDATE RFR) study.

Aims: Randomised controlled trials have reported instantaneous wave-free ratio (iFR) to be non-inferior to fractional flow reserve (FFR) for major adverse cardiovascular events at one year; however, iFR is limited by sensitive landmarking of the pressure waveform, and the assumption that maximal flow and minimal resistance occur during a fixed period of diastole. We sought to validate the resting full-cycle ratio (RFR), a novel non-hyperaemic index of coronary stenosis severity based on unbiased identification of the lowest distal coronary pressure to aortic pressure ratio (Pd/Pa), independent of the ECG, landmark identification, and timing within the cardiac cycle.

Methods And Results: VALIDATE-RFR was a retrospective study designed to derive and validate the RFR.