Henein Michael, Arvidsson Sandra, Pilebro Björn, Backman Christer, Mörner Stellan, Lindqvist Per
Departments of Public Health and Clinical Medicine, Umeå University, Sweden.
Surgical and Peri-Operative Sciences, Umeå University, Sweden.
Int J Cardiol. 2016 Jun 1;212:47-53. doi: 10.1016/j.ijcard.2016.03.041. Epub 2016 Mar 16.
Development of left ventricular outflow tract obstruction (LVOTO) in patients with hypertrophic cardiomyopathy (HCM) is important for explaining symptoms and designing management. LVOTO is mostly caused by a combination of septal hypertrophy and systolic anterior movement of the mitral valve (SAM). The aim of the present study was to determine predictors of exercise induced LVOTO in a group of HCM patients.
We performed supine exercise Doppler echocardiography, including measurements of LV morphology and function and anterior mitral leaflet length, in 51 mildly symptomatic HCM (septal thickness≥15mm) and compared them with 50 healthy controls. Measurements were made at 1) rest, 2) Valsalva maneuver, 3) peak exercise and 4) post exercise. LVOTO was diagnosed as a LVOT gradient of >30mmHg at rest, after Valsalva and after exercise or ≥50mmHg at peak exercise.
All patients stopped exercise because of exhaustion. 35% of the patients had resting LVOTO and 48% during Valsalva. At peak exercise, only 37% had LVOTO, who increased to 64% post exercise. Patients who developed LVOTO at peak exercise were more prone to continue having it post exercise (p<0.001), to have attenuated systolic blood pressure rise (p=0.011) and to have long anterior mitral valve leaflets (p<0.001). Backward multiple regression analysis showed the anterior mitral leaflet length as the strongest single independent predictor (β=0.36, p=0.010) for increased LVOT velocities, followed by basal septal thickness.
In patients with HCM, LV outflow tract obstruction seems to be relatively uncommon during exercise but rather occurring minutes after stopping exercise. Exercise LVOTO seems to be determined by long anterior mitral leaflets in addition to the well established septal hypertrophy.
肥厚型心肌病（HCM）患者左心室流出道梗阻（LVOTO）的发生对于解释症状和制定治疗方案具有重要意义。LVOTO主要由室间隔肥厚和二尖瓣收缩期前向运动（SAM）共同引起。本研究的目的是确定一组HCM患者运动诱发LVOTO的预测因素。
我们对51例症状轻微的HCM患者（室间隔厚度≥15mm）进行了仰卧位运动多普勒超声心动图检查，包括测量左心室形态和功能以及二尖瓣前叶长度，并将其与50例健康对照者进行比较。测量在以下四个阶段进行：1）静息状态；2）瓦尔萨尔瓦动作；3）运动峰值；4）运动后。LVOTO的诊断标准为静息、瓦尔萨尔瓦动作后和运动后左心室流出道压差>30mmHg，或运动峰值时≥50mmHg。
所有患者均因疲劳而停止运动。35%的患者静息时存在LVOTO，瓦尔萨尔瓦动作时为48%。在运动峰值时，只有37%的患者存在LVOTO，运动后这一比例增至64%。在运动峰值时出现LVOTO的患者运动后更易持续存在LVOTO（p<0.001），收缩压上升减弱（p=0.011），且二尖瓣前叶较长（p<0.001）。向后多元回归分析显示，二尖瓣前叶长度是左心室流出道速度增加的最强单一独立预测因素（β=0.36，p=0.010），其次是基底室间隔厚度。
在HCM患者中，左心室流出道梗阻在运动期间似乎相对少见，而是在停止运动数分钟后出现。除了已明确的室间隔肥厚外，运动性LVOTO似乎还由较长的二尖瓣前叶决定。
