早期左、右心室对主动脉瓣膜置换术的反应
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Early Left and Right Ventricular Response to Aortic Valve Replacement
背景与目的
主动脉瓣狭窄患者行主动脉瓣置换术（AVR）对围手术期心肌功能的直接影响尚不清楚。心脏停搏引起的心肌阻滞和缺血再灌注损伤，特别是伴左心室肥厚患者，可能会影响其左心室（LV）功能。另外，AVR后，当后负荷减小时，LV功能可能得到改善。然而，经过心脏停搏后，心脏负荷改善，右心室（RV）功能并未改善。主动脉瓣狭窄患者行AVR对其心肌功能有何影响，尚未得到充分探索。我们的主要目的是用超声心动图测量心肌形变来描述AVR术对左室功能的影响。其次，评估RV功能。
方 法
对参与临床试验（NCT01187329）的100例患者进行补充分析，97例主动脉瓣狭窄患者接受AVR。其中95例患者在开胸前和关胸后接受标准化的经食道超声心动图检查，以测量心脏收缩和舒张功能。使用二维斑点追踪成像超声心动图分析心脏超声图像纵向心肌应变和应变率。比较术前评估的心肌变形情况。手术结束时，采用配对t检验进行多重比较。
结 果
术后左心室容积和动脉血压降低，心率增加。采用超声心动图分析了72例患者LV应变， 67例患者LV应变率，54例患者RV应变和应变率。在72例患者LV应变图像中， 术后9个患者需要肾上腺素，22个需要去甲肾上腺素，2个患者两种药物均需要。手术结束时左室应变与术前相比无变化（差异：0.7 [97.6％置信区间，-0.2〜1.5]％; P = 0.07），而LV收缩期应变率得到改善（变得更负）（-0.3 [-0.4至-0.2] s-1; P <0.001）。相反，尽管术后RV收缩期应变率不变（0.0 [97.6％置信区间，-0.1〜0.1]; P = 0.83），但RV收缩期应变恶化（变得较差）（差异4.6 [3.1〜6.0]％; P <0.001）。
结 论
主动脉瓣狭窄患者行主动脉瓣置换术后能够改善左室纵向应变率从而改善LV功能。相反，通过纵向应变评估，RV功能降低。
原始文献摘要
Andra E. Duncan, MD, MS, Sheryar Sarwar, MD, Babak Kateby Kashy, MD, Abraham Sonny, MD,Shiva Sale, MD, Andrej Alfirevic, MD, Dongsheng Yang, MS, James D. Thomas, MD,Marc Gillinov, MD, and Daniel I. Sessler, MD. Early Left and Right Ventricular Response to Aortic Valve Replacement. Anesth Analg 2017.3
BACKGROUND:The immediate effect of aortic valve replacement (AVR) for aortic stenosis on perioperative myocardial function is unclear. Left ventricular (LV) function may be impaired by cardioplegia-induced myocardial arrest and ischemia-reperfusion injury, especially in patients with LV hypertrophy. Alternatively, LV function may improve when afterload is reduced after AVR. The right ventricle (RV), however, experiences cardioplegic arrest without benefiting from improved loading conditions. Which of these effects on myocardial function dominate in patients undergoing AVR for aortic stenosis has not been thoroughly explored. Our primary objective is thus to characterize the effect of intraoperative events on LV function during AVR using echocardiographic measures of myocardial deformation. Second, we evaluated RV function.
METHODS: In this supplementary analysis of 100 patients enrolled in a clinical trial (NCT01187329), 97 patients underwent AVR for aortic stenosis. Of these patients, 95 had a standardized intraoperative transesophageal echocardiographic examination of systolic and diastolic function performed before surgical incision and repeated after chest closure. Echocardiographic images were analyzed off-line for global longitudinal myocardial strain and strain rate using 2D speckle-tracking echocardiography. Myocardial deformation assessed at the beginning of surgery was compared with the end of surgery using paired t tests corrected for multiple comparisons.
RESULTS: LV volumes and arterial blood pressure decreased, and heart rate increased at the end of surgery. Echocardiographic images were acceptable for analysis in 72 patients for LV strain,
67 for LV strain rate, and 54 for RV strain and strain rate. In 72 patients with LV strain images, 9 patients required epinephrine, 22 required norepinephrine, and 2 required both at the end of
surgery. LV strain did not change at the end of surgery compared with the beginning of surgery (difference:0.7 [97.6% confidence interval, −0.2 to 1.5]%; P = 0.07), whereas LV systolic strain rate improved (became more negative) (−0.3 [−0.4 to −0.2] s−1; P < 0.001). In contrast, RV systolic strain worsened (became less negative) at the end of surgery (difference: 4.6 [3.1 to 6.0]%; P <0.001) although RV systolic strain rate was unchanged (0.0 [97.6% confidence interval, −0.1 to 0.1]; P = 0.83).
CONCLUSIONS: LV function improved after replacement of a stenotic aortic valve demonstrated by improved longitudinal strain rate. In contrast, RV function, assessed by longitudinal strain, was reduced. surgery.
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