Venkateshvaran Ashwin, Sola Srikanth, Govind Satish Chandra, Dash Pravat Kumar, Barooah Banajit, Shahgaldi Kambiz, Sahlén Anders, Lund Lars, Winter Reidar, Nagy Anikó Ilona, Manouras Aristomenis
School for Technology and Health, Royal Institute of Technology, Stockholm, Sweden; Sri Sathya Sai Institute of Higher Medical Sciences, Bangalore, India.
J Physiol. 2015 Apr 15;593(8):1901-12. doi: 10.1113/jphysiol.2014.280404. Epub 2015 Feb 9.
A hallmark of mitral stenosis (MS) is the markedly altered left ventricular (LV) loading. As most of the methods used to determine LV performance in MS patients are influenced by loading conditions, previous studies have shown conflicting results. The present study calculated LV elastance, which is a robust method to quantify LV function. We demonstrate that LV loading in MS patients is elevated but normalizes after valve repair and might be a result of reflex pathways. Additionally, we show that the LV in MS is less compliant than normal due to a combination of right ventricular loading and the valvular disease itself. Immediately after valve dilatation the increase in blood inflow into the LV results in even greater LV stiffness. Our findings enrich our understanding of heart function in MS patients and provide a simple reproducible way of assessing LV performance in MS.
Left ventricular (LV) function in rheumatic mitral stenosis (MS) remains an issue of controversy, due to load dependency of previously employed assessment methods. We investigated LV performance in MS employing relatively load-independent indices robust to the altered loading state. We studied 106 subjects (32 ± 8 years, 72% female) with severe MS (0.8 ± 0.2 cm(2) ) and 40 age-matched controls. MS subjects underwent simultaneous bi-ventricular catheterization and transthoracic echocardiography (TTE) before and immediately after percutaneous transvenous mitral commisurotomy (PTMC). Sphygmomanometric brachial artery pressures and TTE recordings were simultaneously acquired in controls. Single-beat LV elastance (Ees ) was employed for LV contractility measurements. Effective arterial elastance (Ea ) and LV diastolic stiffness were measured. MS patients demonstrated significantly elevated afterload (Ea : 3.0 ± 1.3 vs. 1.5 ± 0.3 mmHg ml(-1) ; P < 0.001) and LV contractility (Ees : 4.1 ± 1.6 vs. 2.4 ± 0.5 mmHg ml(-1) ; P < 0.001) as compared to controls, with higher Ea in subjects with smaller mitral valve area (≤ 0.8 cm(2) ) and pronounced subvalvular fusion. Stroke volume (49 ± 16 to 57 ± 17 ml; P < 0.001) and indexed LV end-diastolic volume (LVEDVindex : 57 ± 16 to 64 ± 16 ml m(-2) ; P < 0.001) increased following PTMC while Ees and Ea returned to more normal levels. Elevated LV stiffness was demonstrated at baseline and increased further following PTMC. Our findings provide evidence of elevated LV contractility, increased arterial load and increased diastolic stiffness in severe MS. Following PTMC, both LV contractility and afterload tend to normalize.
二尖瓣狭窄（MS）的一个标志是左心室（LV）负荷明显改变。由于用于确定MS患者左心室功能的大多数方法都受负荷条件影响，先前的研究结果相互矛盾。本研究计算了左心室弹性，这是一种量化左心室功能的可靠方法。我们证明，MS患者的左心室负荷升高，但在瓣膜修复后恢复正常，这可能是反射通路的结果。此外，我们表明，由于右心室负荷和瓣膜疾病本身的共同作用，MS患者的左心室顺应性低于正常水平。瓣膜扩张后立即进入左心室的血流量增加，导致左心室僵硬度进一步增加。我们的研究结果丰富了我们对MS患者心脏功能的理解，并提供了一种简单可重复的方法来评估MS患者的左心室功能。
由于先前采用的评估方法依赖负荷，风湿性二尖瓣狭窄（MS）患者的左心室（LV）功能仍然存在争议。我们采用相对独立于负荷的指标来研究MS患者的左心室功能，这些指标对改变的负荷状态具有鲁棒性。我们研究了106例严重MS患者（年龄32±8岁，72%为女性，二尖瓣面积0.8±0.2 cm²）和40例年龄匹配的对照组。MS患者在经皮经静脉二尖瓣交界切开术（PTMC）前和术后立即进行双心室导管插入术和经胸超声心动图（TTE）检查。对照组同时采集肱动脉血压和TTE记录。采用单搏左心室弹性（Ees）测量左心室收缩力。测量有效动脉弹性（Ea）和左心室舒张僵硬度。与对照组相比，MS患者的后负荷（Ea：3.0±1.3 vs. 1.5±0.3 mmHg ml⁻¹；P<0.001）和左心室收缩力（Ees：4.1±1.6 vs. 2.4±0.5 mmHg ml⁻¹；P<0.001）显著升高，二尖瓣面积较小（≤0.8 cm²）且有明显瓣下融合的患者Ea更高。PTMC后，每搏量（49±16至57±17 ml；P<0.001）和左心室舒张末期容积指数（LVEDVindex：57±16至64±16 ml m⁻²；P<0.001）增加，而Ees和Ea恢复到更正常的水平。基线时左心室僵硬度升高，PTMC后进一步增加。我们的研究结果提供了证据，表明严重MS患者左心室收缩力升高、动脉负荷增加和舒张僵硬度增加。PTMC后，左心室收缩力和后负荷均趋于正常。
