Is coronary thermodilution as accurate as doppler velocity for measuring coronary flow reserve?

Abstract

Background: Thermodilution coronary flow reserve (CFRthermo) IS a new technique for measuring coronary flow reserve (CFR) using a coronary pressure wire and based on the ability of the pressure transducer to also measure temperature changes. CFRthermois defined as the mean transit time of room temperature saline injected down the LAD at rest divided by the mean transit time at maximal hyperemla. Methods: In an open-chest pig model, CFRthermoin the left anterior descending (LAD) artery was measured and compared to flow reserve from a Doppler wire (CFR doppler), and an external flow probe placed around the LAD (CFRfkxv). In 6 pigs, CFR was measured by all 3 means in the normal LAD and after creation of an epicardial LAD stenosis. In order to determine the added effect of microvascular disease, measurements of flow reserve were also performed after disruption of the coronary microcirculation using embolized microspheres. lntracoronary papaverine (20 mg) was used to induce hyperemia. Methodr and Results: Twenty-three patients (age 52 * 8 years) were studied. A total of 129 PVs were assessed with AcuNav (Acuson) and 80 PVs with 9MHz (Boston Sci) ICE. After RF ablation, peak Doppler velocity at PV ostium increased from 52 * 17 to 74 t 24 cm/s and gradient increased from 1.2 * 0.7 to 2.4 c 1.4’ mmHg, *p < 0.01. Ablation also resulted I” an acute decrease in PV cross-sectional area (CSA) from 3.1 f 1.8 to 1.9 * 1 .I’ err?, increase in wall thickness from 0.7 f 0.2 to 1.6 f 0.7’ mm and loss of its normal motility throughout the cardiac cycle: %change decreased from 27 * 14% to 20 * 8%’ (Fig), ‘p < 0.01. Unablated PVs remained unchanged. Conclusion: RF ablation resulted in acute increases in PV flow velocity and wall thickness and decreases in CSA and motility, although no significant pulmonary stenosis was ’ observed. ICE provides.useful information about PV status in RF catheter ablation.