Background:Determining the functional significance of each individual coronary lesion in patients with serial coronary stenoses is challenging. It has been proposed that nonhyperemic pressure ratios, such as the instantaneous wave free ratio (iFR) and the ratio of resting distal to proximal coronary pressure (Pd/Pa) are more accurate than fractional flow reserve (FFR) because autoregulation should maintain stable resting coronary flow and avoid hemodynamic interdependence (cross-talk) that occurs during hyperemia. This study aimed to measure the degree of hemodynamic interdependence of iFR, resting Pd/Pa, and FFR in a porcine model of serial coronary stenosis.Methods:In 6 anesthetized female swine, 381 serial coronary stenoses were created in the left anterior descending artery using 2 balloon catheters. The degree of hemodynamic interdependence was calculated by measuring the absolute changes in iFR, resting Pd/Pa, and FFR across the fixed stenosis as the severity of the other stenosis varied.Results:The hemodynamic interdependence of iFR, resting Pd/Pa, and FFR was 0.039±0.048, 0.021±0.026, and 0.034±0.034, respectively (all P<0.001). When the functional significance of serial stenoses was less severe (0.70–0.90 for each index), the hemodynamic interdependence was 0.009±0.020, 0.007±0.013, and 0.017±0.022 for iFR, resting Pd/Pa, and FFR, respectively (all P<0.001). However, in more severe serial coronary stenoses (<0.60 for each index), hemodynamic interdependence was 0.060±0.050, 0.037±0.030, and 0.051±0.037 for iFR, resting Pd/Pa, and FFR, respectively (all P<0.001).Conclusions:When assessing serial coronary stenoses, nonhyperemic pressure ratios are affected by hemodynamic interdependence. When the functional significance of serial coronary stenoses is severe, the effect is similar to that which is seen with FFR.

中文翻译：

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连续冠状动脉狭窄对各种冠状动脉生理指标的影响

背景：确定连续冠状动脉狭窄患者中每个单独冠状动脉病变的功能意义具有挑战性。有人提出非高血压比，例如瞬时无波比 (iFR) 和静息冠状动脉远端与近端的比值 (Pd/Pa) 比血流储备分数 (FFR) 更准确，因为自动调节应该保持稳定的静息状态冠状动脉血流并避免充血期间发生的血流动力学相互依赖性（串扰）。本研究旨在测量连续冠状动脉狭窄的猪模型中 iFR、静息 Pd/Pa 和 FFR 的血流动力学相互依赖性程度。方法：在 6 头麻醉的母猪中，使用 381 个连续冠状动脉狭窄在左前降支中产生2 个球囊导管。P <0.001)。当连续狭窄的功能意义不太严重时（每个指标为 0.70-0.90），iFR、静息 Pd/Pa 和 FFR 的血流动力学相互依赖性分别为 0.009±0.020、0.007±0.013 和 0.017±0.022（所有P <0.001)。然而，在更严重的系列冠状动脉狭窄中（每个指标<0.60），iFR、静息 Pd/Pa 和 FFR 的血流动力学相互依赖性分别为 0.060±0.050、0.037±0.030 和 0.051±0.037（均P <0.001）。结论：在评估连续冠状动脉狭窄时，非高血压比受血流动力学相互依赖性的影响。当连续冠状动脉狭窄的功能意义很严重时，其效果与 FFR 所见的效果相似。