Anesthesia Service, Clement J. Zablocki Veterans Affairs Medical Center, Milwaukee, WI 53295, USA.
J Cardiothorac Vasc Anesth. 2012 Jun;26(3):376-80. doi: 10.1053/j.jvca.2011.10.011. Epub 2011 Dec 23.
Transmitral blood flow during early left ventricular (LV) filling produces an intraventricular rotational body of fluid known as a "vortex ring" that enhances the hydraulic efficiency of early LV filling. The authors tested the hypothesis that exposure to cardiopulmonary bypass (CPB) attenuates intraventricular vortex formation time (VFT) in patients with normal preoperative LV systolic and diastolic function undergoing coronary artery bypass graft (CABG) surgery.
A prospective, observational study.
Ten men (65 ± 4 years, 91 ± 11 kg, and 175 ± 8 cm) with a normal preoperative LV ejection fraction (58% ± 6%) scheduled for elective CABG surgery were studied after institutional review board approval.
None.
Anesthesia was induced with etomidate, fentanyl, and rocuronium and maintained with isoflurane. Myocardial protection during CPB consisted of antegrade and retrograde cold blood cardioplegia administered at 15-minute intervals, systemic and topical hypothermia, and warm continuous antegrade cardioplegia before aortic cross-clamp removal. The peak early LV filling and atrial systole blood flow velocities (E and A, respectively) and corresponding velocity-time integrals (VTI-E and VTI-A, respectively) were obtained with pulse-wave Doppler echocardiography and used to determine E/A and atrial filling fraction (β, VTI-A/[VTI-E + VTI-A]), respectively. Mitral valve diameter (D) was calculated as the average of minor and major axis lengths obtained in the midesophageal bicommissural and long-axis transesophageal echocardiographic imaging planes, respectively. VFT was calculated 30 minutes before and 15, 30, and 60 minutes after CPB as 4 × (1 - β) × stroke volume (SV)/πD(3), where SV is the stroke volume measured using thermodilution. All patients separated from CPB in sinus rhythm without pacing or vasoactive drug support. Systemic and pulmonary hemodynamics were similar before compared with all times after CPB. CPB significantly (p < 0.05) reduced VFT (5.3 ± 1.8 to 4.0 ± 1.5 15 minutes after CPB); the recovery of VFT (to 4.7 ± 1.6, p > 0.05 v baseline) was noted 60 minutes after CPB. A reduction in E/A (1.26 ± 0.22 to 0.96 ± 0.27) and an increase in β (0.33 ± 0.04 to 0.41 ± 0.07) occurred 15 minutes after CPB. E/A and β also recovered gradually toward control values after CPB (1.25 ± 0.22 and 0.36 ± 0.04, respectively, 60 minutes after CPB; p > 0.05 v. baseline).
The results indicated that CPB transiently attenuate VFT in patients with normal preoperative LV systolic and diastolic function undergoing CABG surgery. These data suggest that CPB adversely affects diastolic transmitral flow efficiency by reducing intraventricular vortex ring formation in vivo.
左心室（LV）早期充盈期间的二尖瓣血流产生一个称为“涡环”的腔内旋转液体体，从而增强早期 LV 充盈的液压效率。作者测试了以下假说，即在接受心肺旁路（CPB）的患者中，正常术前 LV 收缩和舒张功能的患者的室间隔涡旋形成时间（VFT）会减弱，这些患者正在接受冠状动脉旁路移植术（CABG）手术。
前瞻性观察研究。
十名男性（65 ± 4 岁，91 ± 11 kg，175 ± 8 cm），术前 LV 射血分数正常（58% ± 6%），计划接受择期 CABG 手术，在机构审查委员会批准后进行研究。
无。
用依托咪酯、芬太尼和罗库溴铵诱导麻醉，并使用异氟醚维持麻醉。CPB 期间的心肌保护包括顺行和逆行冷血心脏停搏液，每 15 分钟给予一次，全身和局部低温，以及主动脉夹闭前的温连续顺行心脏停搏液。使用脉冲波多普勒超声心动图获得早期 LV 充盈和心房收缩血流速度（E 和 A，分别）和相应的速度时间积分（VTI-E 和 VTI-A，分别），并分别用于确定 E/A 和心房充盈分数（β，VTI-A/[VTI-E + VTI-A]）。二尖瓣直径（D）通过在中食管双交界和长轴经食管超声心动图成像平面中分别获得的小轴和大轴长度的平均值来计算。VFT 在 CPB 前 30 分钟和 CPB 后 15、30 和 60 分钟测量 3 次，计算公式为 4 ×（1-β）×SV/πD(3)，其中 SV 是使用热稀释法测量的每搏量。所有患者均在窦性心律下从 CPB 中分离出来，无需起搏或血管活性药物支持。与 CPB 前相比，CPB 后全身和肺血流动力学相似。CPB 显著（p < 0.05）降低 VFT（5.3 ± 1.8 至 4.0 ± 1.5，CPB 后 15 分钟）；CPB 后 60 分钟时观察到 VFT 的恢复（至 4.7 ± 1.6，p > 0.05 与基线相比）。E/A（1.26 ± 0.22 至 0.96 ± 0.27）降低，β（0.33 ± 0.04 至 0.41 ± 0.07）增加，CPB 后 15 分钟即可观察到。E/A 和 β 在 CPB 后逐渐恢复到对照值（CPB 后 60 分钟时分别为 1.25 ± 0.22 和 0.36 ± 0.04，p > 0.05 与基线相比）。
结果表明，CPB 可短暂减弱正常术前 LV 收缩和舒张功能患者 CABG 手术中的 VFT。这些数据表明，CPB 通过减少体内室间隔涡环形成，对舒张期经二尖瓣血流效率产生不利影响。
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