Tissue tracking of segmental strain as a predictor of provoked dynamic left ventricular outflow tract obstruction

BackgroundLeft ventricular outflow tract obstruction (LVOTO) is commonly observed in patients with hypertrophic cardiomyopathy (HCM) or left ventricular hypertrophy (LVH). Some patients develop LVOTO provoked by physical exertion, and hence termed dynamic LVOTO (DLVOTO). However, its precise prevalence and mechanism are still unclear.AimTwo-dimensional speckle tracking echocardiography (2D STE) seems to be helpful for the detection of early LV structural abnormalities. This study aimed to examine the possible role of segmental as well as global longitudinal strain in identifying DLVOTO non-HCM patients as detected by dobutamine stress echocardiography (DSE).Methods and resultsTwo hundred and fifty patients without structural heart disease had undergone conventional transthoracic echocardiography, 2D STE, and DSE. All patients with non-ischemic evidence were divided into two groups according to the DSE results; DLVOTO (+) and DLVOTO (?).Among 250 patients, 50 patients (36%) had shown DLVOTO after DSE (15 males, 35 females; mean age 55±7years). They were compared with 90 non -LVOTO obstruction patients (43 males, 47 females; mean age 57±6years). Based on multivariate logistic regression analysis, the independent predictors of provoked DLVOTO during DSE were resting basal septal longitudinal strain BS-LS _average (p < 0.001), resting LA reservoir strain (p < 0.001), and systolic LVOT diameter (p = 0.03). Resting BS-LS _average with cut-off - 17.5% was recognized as a critical indicator of DLVOTO, with sensitivity 78%, and specificity 95% (better than systolic LVOT diameter of sensitivity 76%, and specificity 15% and resting LA reservoir strain which showed poor AUC at ROC curve 0.007).ConclusionWe demonstrate that provoked LVOTO during DSE in non HCM symptomatic patients is directly correlated to resting regional LS, where the increased BS-LS of ≥ ?17.5% was a key determinant of LVOT gradient provocation. Assessment of baseline BS-LS _average might be a bedside simple tool for detection of patients with DLVOTO not able to do DSE.     

Dobutamine in elderly septic shock patients refractory to dopamine

The hemodynamic effects of dobutamine (2.5–20 g/kg per min) were studied in six elderly patients with septic shock which was refractory to dopamine (15 g/kg per min). Dobutamine infusion resulted in significant increases in cardiac index (CI), stroke index (SI) and left ventricular stroke work index (LVSWI) and similar declines in heart rate (HR), mean pulmonary artery pressure (MPAP), pulmonary capillary wedge pressure (PCWP), systemic vascular resistance (SVR) and total pulmonary resistance (TPR). Dose response curves demonstrated a linear rise in CI with increasing doses of dobutamine and parallel decreases in HR and PCWP. MAP was unchanged. These data indicate that dobutamine may be a useful adjunct to dopamine therapy in the management of elderly patients with septic shock.     

低剂量多巴酚丁胺超声心动图预测经皮腔内冠脉成形术后冬眠心肌功能改善的价值

对经皮腔内冠脉成形术（PTCA）成功的24例慢性冠心病患者术前低剂量多巴酚丁胺超声（DE）和术后平静超声（38．3天）进行分析。结果：术前基础状态室壁运动异常154节段；DE心肌收缩力储备阳性84节段（54．5％），PTCA术后功能改善91节段（59．1％），P＞0．05。以DE心肌收缩力储备阳性预测PTCA术后节段室壁运动改善，敏感性84．6％、特异性88．9％、阳性预测值91．7％、阴性预测值80％。结果表明：DE可识别冬眠心肌和准确地预测PTCA术后局部左室功能的改善。     

小剂量多巴酚丁胺负荷超声心动图结合多普勒组织成像评价存活心肌的研究

目的：研究多普勒组织成像（DTI）结合小剂量多巴酚丁胺负荷超声心动图评价心肌活性的可行性，并研究其与^99mTc-MIBI硝酸甘油介入心肌显像在评价存活心肌方面的一致性。方法：对30例经冠状动脉造影确冠心病的患者行超声心动图及心脏核素检查，超声心动图检查使用DTI速度模式，采用两级多巴酚丁胺超声心动图试验，所有患者均行静息显像及硝酸甘油介入后显像，结果：（1）30例冠心病患者用超声心动图静息DTI检测480个室壁节段，检出166个运动常节段，运动减弱节段108个，运动消失节段58个。（2）对患者行超声心动图小剂量多巴酚丁胺负荷试验DTI检测480个室壁节段，检出166个运动异常节段中89个节段运动改善，提示为存活心肌节段（A组）；余77个节段无变化，为坏死心肌（B组）。A组静息及负荷超声心动图DTI差异有显著性意义（P＜0．05），B组静息及负荷超声心动图DTI差异无显著性意义（P＞0．05）。A组与B组静息超心动图DTI差异无显著性意义（P＞0．05）。（3）30例冠心病患者用^99mTc-MIBI硝酸甘油介入心肌显像检测480个室壁节段，检出185个病变节段，其中97个为存活心肌节段，小剂量多巴酚丁胺结合超声心动图DTI诊断存活心肌的敏感性达83％，特异性达86％，结论：DTI结合小剂量多巴酚丁胺是评心肌活性的一项超声新技术，其结果与^99mTc-MIBI硝酸甘油介入心肌显像进行对照分析显示良好的一致性，应用前景较为乐观。     

多普勒组织成像技术分析冠心病患者多巴酚丁胺超声负荷试验中缺血心肌运动的变化

目的：探讨多普勒组织成像技术（DIT）定量分析多巴酚丁胺超声负荷试验（DSE）过程中缺血心肌室壁运动的特征。方法：分别对14例正常人和20例冠心病患者采用标准的DSE方案（0－40μg.kg^-1.min^-1），使用DIT技术于静息状态，小剂量（10μg.kg^-1.min^-1）及峰值剂量（40μg.kg^-1.min^-1）负荷时观察心肌运动速度的变化，记录各室壁节段收缩期的峰值速度，峰值速度运动时间，综合计算平均收缩期室壁运动峰值速度和平均峰值速度运动时间，结果：随着多巴酚丁胺药物剂量的增加，正常组平均峰值速度均逐渐增加，平均峰值速度运动时间逐渐缩短；冠心病组平均峰值速度小剂量负荷时增加，大剂量时则下降，平均峰值速度运动时间呈逐渐缩短趋势，两组间各指标相比差异有显著性意义（P＜0．001）。结论：DTI技术与DSE结合可定量评价缺血心肌室壁运动异常，对冠心病缺血心肌的无创性诊断具有应用价值。     

Assessment of cardiovascular physiology using dobutamine stress cardiovascular magnetic resonance reveals impaired contractile reserve in patients with cirrhotic cardiomyopathy

Background

Liver cirrhosis has been shown to affect cardiac performance. However cardiac dysfunction may only be revealed under stress conditions. The value of non-invasive stress tests in diagnosing cirrhotic cardiomyopathy is unclear. We sought to investigate the response to pharmacological stimulation with dobutamine in patients with cirrhosis using cardiovascular magnetic resonance.

Methods

Thirty-six patients and eight controls were scanned using a 1.5 T scanner (Siemens Symphony TIM; Siemens, Erlangen, Germany). Conventional volumetric and feature tracking analysis using dedicated software (CMR42; Circle Cardiovascular Imaging Inc, Calgary, Canada and Diogenes MRI; Tomtec; Germany, respectively) were performed at rest and during low to intermediate dose dobutamine stress.

Results

Whilst volumetry based parameters were similar between patients and controls at rest, patients had a smaller increase in cardiac output during stress (p = 0.015). Ejection fraction increase was impaired in patients during 10 μg/kg/min dobutamine as compared to controls (6.9 % vs. 16.5 %, p = 0.007), but not with 20 μg/kg/min (12.1 % vs. 17.6 %, p = 0.12). This was paralleled by an impaired improvement in circumferential strain with low dose (median increase of 14.4 % vs. 30.9 %, p = 0.03), but not with intermediate dose dobutamine (median increase of 29.4 % vs. 33.9 %, p = 0.54). There was an impaired longitudinal strain increase in patients as compared to controls during low (median increase of 6.6 % vs 28.6 %, p < 0.001) and intermediate dose dobutamine (median increase of 2.6%vs, 12.6 % p = 0.016). Radial strain response to dobutamine was similar in patients and controls (p > 0.05).

Conclusion

Cirrhotic cardiomyopathy is characterized by an impaired cardiac pharmacological response that can be detected with magnetic resonance myocardial stress testing. Deformation analysis parameters may be more sensitive in identifying abnormalities in inotropic response to stress than conventional methods.     

微量注射泵泵入硝酸甘油、多巴胺、多巴酚丁胺治疗难治性心力衰竭的临床效果观察

目的：观察应用微量注射泵泵入硝酸甘油、多巴胺、多巴酚丁胺治疗难治性心力衰竭的临床疗效。方法选择2011年1月~2014年1月本院102例心功能Ⅲ~Ⅳ级(NYHA分级法)的住院患者,在卧床休息、控制饮食、吸氧、强心剂及利尿剂治疗的基础上,应用微量注射泵泵入硝酸甘油、多巴胺、多巴酚丁胺,疗程3~5d,观察患者临床症状、体征、心功能改善情况。结果102例患者用药后临床症状和心功能各项参数均明显改善,与治疗前比较,差异有统计学意义(P<0.05)。结论应用微量泵泵入硝酸甘油、多巴胺、多巴酚丁胺治疗难治性心力衰竭患者疗效明显,安全可靠。     

老年感染性休克患者液体复苏后多巴酚丁胺的治疗作用及评 价指标研究

目的 探讨老年感染性休克患者初步液体复苏后,采用心功能指数 （CFI） 评估多巴酚丁胺对患者血管外肺水指数 （EVLWI）、组织灌注及氧代谢的影响。 方法 选择 ICU 中感染性休克患者 60 例,均置入 PiCCO 导管,接受初步液体复苏后 GEDVI≥680ml/m2 且 SVV＜10%,应用多巴酚丁胺并于 6h 后根据 CFI 将患者分为 CFI 达标组 32 例（CFI≥4.1）和 CFI 未达标组 28 例（CFI＜4.1）,分别记录应用多巴酚丁胺前及 6h 后两组患者的心率、收缩压、舒张压、平均动脉压（MAP）、中心静脉压（CVP）、心指数 （CI）、全心舒张末容积指数（GEDVI）、EVLWI、CFI、全心射血分数（GEF）血流动力学参数;记录乳酸、乳酸清除率、氧合指数（PO2/FiO2）、 中心静脉血氧饱和度（ScvO2）等全身灌注及氧代谢指标。 结果 达标组患者 CI、CFI、GEF 较治疗前明显升高,GEDVI、EVLWI 较治 疗前明显降低（均 P＜0.05）。与未达标组用药 6h 后相比,达标组患者 CI、CFI、GEF 升高更明显（均 P＜0.05）,EVLWI 下降更明显（P＜ 0.05）。两组患者治疗后乳酸水平均逐渐下降,达标组较未达标组患者乳酸降低更明显（P＜0.05）,乳酸清除率更高（P＜0.05）。治疗后, 达标组较未达标组 ScvO2 达标（即 ScvO2≥70%）的例数更多（P＜0.05）。 结论 经过初步液体复苏后 GEDVI≥680ml/m2 且 SVV＜ 10%的老年感染性休克患者应用多巴酚丁胺优化心脏收缩功能,CFI≥4.1 时患者 EVLWI 明显降低、组织灌注及氧代谢水平得到改善。