Introduction
Fluctuations in heart rate (HR), area stenosis (AS), and contractility (CY) are likely to occur during coronary catheterization procedures. For improved functional diagnostics, evaluation of coronary circulation should rely on methods independent of these hemodynamic changes. This study evaluates the influence of CY and HR on both fractional flow reserve (FFR) and an alternative diagnostic index, pressure drop coefficient (CDP e ).
Methods
Simultaneous measurements of distal hyperemic coronary-arterial pressure drop (dp) and average peak flow velocity (APV) were performed on seven pigs (42±3 kg), using a dual sensor-tipped guide wire (Volcano Therapeutics). Left ventricular pressure (LVP) was measured with a 5F Mikro-Tip Catheter (Millar Instruments) connected to a Sonometric system. Angioplasty balloons were used to create desired blockage. CDP e was calculated as (dp)/(0.5⁎1.05⁎APV 2 ). CY was calculated by differentiating LVP signals, obtaining left ventricular (dp/d t ) max , an index of CY. To investigate the effect of HR and CY on FFR and CDP e , these indices were computed for “<50%AS” and “>50%AS,” during atrial pacing at HR <110 and HR >110 bpm. A total of 90 measurements were obtained. A two-way repeated measures ANOVA was performed.
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