Escaned Javier, Cortés Jorge, Flores Alex, Goicolea Javier, Alfonso Fernando, Hernández Rosana, Fernández-Ortiz Antonio, Sabaté Manel, Bañuelos Camino, Macaya Carlos
Interventional Cardiology Service, Cardiovascular Institute, Hospital Clínico San Carlos, Madrid, Spain.
J Am Coll Cardiol. 2003 Jul 16;42(2):226-33. doi: 10.1016/s0735-1097(03)00588-6.
This study reports a comparative assessment of the hemodynamic relevance of myocardial bridges (MB) using two modalities of fractional flow reserve (FFR), with and without concomitant inotropic challenge.
Extravascular coronary compression by means of MB is modulated by myocardial inotropism and causes intracoronary systolic pressure overshooting and negative systolic gradients across the MB. The former characteristic suggests that adequate hemodynamic assessment of MB should include inotropic stimulation. The latter characteristic might interfere with FFR by decreasing the mean pressure gradient.
We compared the hemodynamic relevance of 12 lone MB in symptomatic patients using conventional (mean) and diastolic FFR. Diastolic FFR was obtained from post-processed, digitally acquired electrocardiogram and pressure signals. Previously validated cut off values of 0.75 (mean FFR) and 0.76 (diastolic FFR) for hemodynamic relevance were used. Measurements were performed at baseline and after incremental intravenous dobutamine doses.
Fractional flow reserve decreased during dobutamine challenge: mean FFR was 0.90 +/- 0.04 at baseline and 0.84 +/- 0.06 after dobutamine (p = 0.0008); similarly, diastolic FFR was 0.88 +/- 0.05 and 0.77 +/- 0.10 before and after dobutamine, respectively (p = 0.0006). Diastolic FFR identified hemodynamic relevance in five patients, whereas mean FFR did so in only one patient. The discrepancy between mean FFR and diastolic FFR increased with dobutamine challenge: the ratio of mean FFR/diastolic FFR was 1.03 at baseline and 1.09 after dobutamine (p = 0.02). During the administration of dobutamine, the discrepancy was inversely related to the systolic pressure gradient (r = 0.58, P = 0.04).
Physiologic assessment of MB should include dobutamine challenge. Because the overshooting of systolic pressure interferes with and is a cause of error in FFR measurements based on mean pressures, diastolic FFR appears to be the technique of choice for MB assessment, whereas mean FFR should be used with caution.
本研究报告了使用两种血流储备分数（FFR）模式，在有或没有伴随的正性肌力刺激情况下，对心肌桥（MB）血流动力学相关性的比较评估。
MB引起的血管外冠状动脉压迫受心肌收缩性调节，并导致冠状动脉内收缩压过冲以及MB处的负性收缩期梯度。前一特征表明，对MB进行充分的血流动力学评估应包括正性肌力刺激。后一特征可能通过降低平均压力梯度而干扰FFR。
我们使用传统（平均）FFR和舒张期FFR比较了12例有症状患者中孤立MB的血流动力学相关性。舒张期FFR从经后处理的数字化采集的心电图和压力信号中获得。使用先前验证的血流动力学相关性临界值0.75（平均FFR）和0.76（舒张期FFR）。在基线和静脉注射多巴酚丁胺剂量递增后进行测量。
多巴酚丁胺刺激期间血流储备分数降低：平均FFR在基线时为0.90±0.04，多巴酚丁胺后为0.84±0.06（p = 0.0008）；同样，舒张期FFR在多巴酚丁胺前后分别为0.88±0.05和0.77±0.10（p = 0.0006）。舒张期FFR在5例患者中确定了血流动力学相关性，而平均FFR仅在1例患者中确定了血流动力学相关性。平均FFR与舒张期FFR之间的差异随多巴酚丁胺刺激而增加：平均FFR/舒张期FFR的比值在基线时为1.03，多巴酚丁胺后为1.09（p = 0.02）。在多巴酚丁胺给药期间，差异与收缩期压力梯度呈负相关（r = 0.58，P = 0.04）。
对MB的生理学评估应包括多巴酚丁胺刺激。由于收缩压过冲会干扰基于平均压力的FFR测量并导致测量误差，舒张期FFR似乎是评估MB的首选技术，而平均FFR应谨慎使用。
