Systolic anterior motion begins at low left ventricular outflow tract velocity in obstructive hypertrophic cardiomyopathy
Systolic anterior motion begins at low left ventricular outflow tract velocity in obstructive hypertrophic cardiomyopathy
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DOI：
10.1016/s0735-1097(00)00830-5
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发表时间：
2000-10-01
影响因子：
24
通讯作者：
Pearle, G
中科院分区：
文献类型：
--
作者：
Sherrid, MV;Gunsburg, DZ;Pearle, G
目的 本研究的目的是确定二尖瓣收缩性前移 (SAM) 的动力原因是文丘里机制还是血流阻力（推力）机制。 背景 在梗阻性肥厚型心肌病 (HCM) 中，如果 SAM 是由文丘里机制引起的，则在 SAM 发作时应发现左心室流出道 (LVOT) 中的高流速。然而，如果发现速度正常，这将支持替代机制。方法我们通过超声心动图研究了 25 名阻塞性 HCM 患者，这些患者的平均流出道梯度为 82 +/- 6 mm Hg。我们将二尖瓣 M 型超声心动图描记与同一研究中记录的连续波 (CW) 和脉冲波 (PW) 多普勒描记进行了比较。总共对 98 个 M 模式、159 个 CW 和 151 个 PW 多普勒描记进行了数字化和分析。对于每位患者，我们确定了 SAM 发作时的 LVOT CW 速度。这是通过首先从多个 M 模式追踪确定从 Q 波到 SAM 开始的平均时间间隔来完成的。然后，在 Q 波之后的相同时间间隔测量流出道中的 CW 速度。 结果 收缩期前向运动在 Q 波出现后平均 71 +/- 5 ms 开始。 SAM 开始时 LVOT 中的平均 CW 多普勒速度为 89 +/- 8 cm/s。在 68% 的病例中，SAM 在 CW 和 PW 多普勒 LV 射血开始之前开始。 结论 收缩期前运动以正常 LVOT 速度开始。在 SAM 开始时，虽然流出道中存在文丘里力，但其大小比之前假设的要小得多；文丘里机制无法解释 SAM。这些速度数据以及对患者的形状、方向和时间观察表明，阻力（流动的推力）是导致 SAM 的主要流体动力。 (J Am Coll Cardiol 2000；36: 1344-54) (C) 2000 年，美国心脏病学会。
OBJECTIVES The purpose of this study was to determine whether the dynamic cause for mitral systolic anterior motion (SAM) is a Venturi or a flow drag (pushing) mechanism.BACKGROUND In obstructive hypertrophic cardiomyopathy (HCM), if SAM were caused by the Venturi mechanism, high flow velocity in the left ventricular outflow tract (LVOT) should be found at the time of SAM onset. However, if the velocity was found to be normal, this would support an alternative mechanism.METHODS We studied with echocardiography 25 patients with obstructive HCM who had a mean outflow tract gradient of 82 +/- 6 mm Hg. We compared mitral valve M-mode echocardiogram tracings with continuous wave (CW) and pulsed wave (PW) Doppler tracings recorded on the same study. A total of 98 M-mode, 159 CW, and 151 PW Doppler tracings were digitized and analyzed. For each patient we determined the LVOT CW velocity at the time of SAM onset. This was done by first determining the mean time interval from Q-wave to SAM onset from multiple M-mode tracings. Then, CW velocity in the outflow tract was measured at that same time interval following the Q wave.RESULTS Systolic anterior motion began mean 71 +/- 5 ms after Q-wave onset. Mean CW Doppler velocity in the LVOT at SAM onset was 89 +/- 8 cm/s. In 68% of cases SAM began before onset of CW and PW Doppler LV ejection.CONCLUSIONS Systolic anterior motion begins at normal LVOT velocity. At SAM onset, though Venturi forces are present in the outflow tract, their magnitude is much smaller than previously assumed; the Venturi mechanism cannot explain SAM. These velocity data, along with shape, orientation and temporal observations in patients, indicate that drag, the pushing force of flow, is the dominant hydrodynamic force that causes SAM. (J Am Coll Cardiol 2000;36: 1344-54) (C) 2000 by the American College of Cardiology.