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.     

多巴酚丁胺负荷实验对家猪急性冬眠心肌模型QT离散度影响的实验研究

目的 观察多巴酚丁胺负荷期间QT离散度(QTd)的变化情况,探讨其临床意义.方法 对13只小型中国家猪采用闭胸介入法制备急性冬眠心肌模型(右冠状动脉为靶血管),利用多巴酚丁胺超声负荷实验(DSE,0～40 μg·Kg-1·min-1)检出冬眠心肌,之后成功复灌,处死动物,对心脏行TTC大体染色及光镜检查.分别于模型制备前后、DSE期间及复灌后观察QTd的变化情况.结果 ①10只动物(76.92%)成功制备成模型,病理检查未示心肌坏死改变.②模型制备成功后QTd较正常状态明显增加[(68.75±5.33)ms和(25.00±1.77)ms,P＜0.05];复灌后明显降低[(35.62±3.47)ms和(68.75±5.33)ms,P＜0.05],与正常状态差异无统计学意义[(35.62±3.47)ms和(25.00±1.77)ms,P＞0.05].③DSE期间QTd呈现先降低后增加的双相反应的变化趋势.④模型制备成功后的QTd与DSE检出的急性冬眠心肌节段数呈中等程度的负相关(r=-0.64,P＜0.05).结论 ①.急性冬眠心肌动物模型的QTd明显增加,早期有效复灌可降低QTd.②DSE期间急性冬眠心肌模型的QTd呈现双相反应趋势.③急性冬眠心肌模型的QTd是反映冬眠心肌数量的指标之一.     

多巴酚丁胺负荷超声心动图试验

对多巴酚丁胺负荷超声心动图试验诊断冠心病的理论基础、方法学及临床应用价值作一综述     

多巴酚丁胺负荷及运动试验~(99m)Tc-MIBI心肌断层显像与冠状动脉造影的对比研究

比较６９例冠心病患者多巴酚丁胺负荷９９ｍＴｃ甲氧基异丁基异腈（ＭＩＢＩ）心肌断层显像与８２例运动试验９９ｍＴｃＭＩＢＩ心肌断层显像的结果，以探讨它们对冠心病的诊断价值。结果表明：以冠状动脉造影结果为标准，多巴酚丁胺负荷诊断冠心病的敏感性和特异性分别为９１２％和８００％，运动试验分别为８９４％和８２９％。多巴酚丁胺负荷检出冠状动脉病变的敏感性和特异性：左前降支为７８１％和９１３％，回旋支为６６７％和９８２％，右冠状动脉为１００％和８３７％；运动试验分别为７８３％和９１１％，６００％和９６８％，９０９％和８５０％，差异均无显著性（Ｐ＞００５）。提示两者结果相近，对于不能进行运动试验的病人，多巴酚丁胺试验是一种有价值的诊断冠心病的方法。     

多巴酚丁胺负荷超声心动图及组织多普勒成像技术在诊断冠心病中的临床应用

目的探讨多巴酚丁胺负荷超声心动图(DSE)和组织多普勒成像技术(TDI)在冠心病(CHD)诊断中的应用价值,以寻求一种敏感的、无创的CHD诊断方法。方法选择胸闷或胸痛怀疑CHD患者40例,应用TDI测量静息状态(Rest)下前壁中段收缩峰值速度(Vs),以及多巴酚丁胺峰值负荷状态(Peak)下前壁中段Vs,同时测量静息心率和负荷心率;所有入选对象均进行冠脉造影,并根据左前降支狭窄程度是否大于等于50%分为左前降支狭窄组(LST组)与左前降支非狭窄组(non-LST组)。分别比较Rest和Peak前壁中段LST组与non-LST组平均Vs差别等。结果Rest前壁中段LST组与non-LST组Vs差别无显著性意义;但Peak前壁中段LST组与non-LST组差别有显著性意义。结论DSE结合TDI是诊断冠心病有价值的定量分析方法。DSE在诊断CHD时的敏感性、准确性明显优于静息状态超声心动图。     

RETRACTED ARTICLE: Effects of dobutamine on the fatigued diaphragm: A comparison with dopamine

We examined the effects of dopamine (DOA) 10 μg·kg⁻¹·min⁻¹ I.V. and dobutamine (DOB) 10 μg·kg⁻¹. min⁻¹ I.V. on the contractility of the fatigued diaphragm in 26 anesthetized, mechanically ventilated dogs. Animals were divided into two groups of 13 each: the DOA and DOB groups. Diaphragmatic fatigue was induced by intermittent supramaximal bilateral electrophrenic stimulation at a frequency of 20 Hz applied for 30 min. Diaphragmatic contractility was assessed from changes in transdiaphragmatic pressure (P_di). After diaphragmatic fatigue, P_di at low-frequency (20 Hz) stimulation decreased significantly compared with the prefatigue value (P<0.05), whereas no change in P_di was observed at high-frequency (100 Hz) stimulation. In the fatigued diaphragm, P_di at both stimuli increased with an infusion of either DOA (P<0.05) or DOB (P<0.05). The increase of P_di at 20 Hz stimulation was significantly larger in the DOB group compared with that of the DOA group (P<0.05). In each group, P_di at both stimuli decreased after the cessation of administration. The integrated diaphragmatic electric activity (E_di) in the two groups did not change at any frequency of stimulation throughout the study. We conclude that DOB in comparison with DOA is more effective in improving the contractility of the fatigued diaphragm.     

硝酸甘油加多巴酚丁胺治疗难治性心力衰竭体会

目的 :探讨用硝酸甘油加多巴酚丁胺治疗难治性心力衰竭。方法 :以阳泉钢铁集团有限公司医院 30例顽固性心力衰竭患者为研究对象 ,其中男性 18例 ,女性 12例 ,年龄 37岁～ 81岁 ,平均 5 6岁 ,心功能均为 级～ 级 ,在综合治疗同时 ,加用小剂量硝酸甘油加多巴酚丁胺开始 ,以后据病情逐渐增加剂量 ,把血压维持在正常水平 ,结果 :30例患者中 ,显效 2 0例 ,有效 9例 ,无效 1例 ,总有效率 96 .6 %。结论 :在强心、利尿等基础治疗的前提下 ,用硝酸甘油加多巴酚丁胺治疗难治性心力衰竭 ,既能通过多巴胺直接增强心肌收缩力作用 ,增加心排血量 ,提高血压 ,抵消硝酸甘油不良反应 ,可能发挥硝酸甘油扩张动、静脉 ,减轻心脏前后负荷 ,改善全身及肾血流灌注 ,在临床上值得进一步研究探讨     

多巴酚丁胺^99m锝心肌断层显象评价冠状动脉介入性治疗的效果

用多巴酚丁胺９９ｍ锝－ＭＩＢＩ（ｍｅｔｈｏｘｙｉｓｏｂｕｔｙｌｎｉｔｒｉｌｅ）心肌断层显象（Ｄｏｂｕ－ＥＣＴ）评价冠心病介入性治疗的效果。方法对３２例冠心病患者在冠状动脉介入治疗的术前、术后３～６个月行多巴酚丁胺心肌显象。多巴酚丁胺以５～４０μｇ．ｋｇ－１／ｍｉｎ，每级剂量间隔３分钟。在最大剂量时注射７４０ＭＢｑ９９ｍ锝－ＭＩＢＩ，１小时后行心肌断层显象。２４小时后再注射等量３９９ｍ锝－ＭＩＢＩ行静态心肌显象。结果术前显示１１６个异常室壁节段，术后显示７９个节段缺血消失或缺血改善，术前心肌显象有明显可逆性心肌缺损节段，治疗有效率为７５％；而术前仅呈固定缺损节段，治疗有效率为４３．８％（Ｐ＜０．０１）。术前心脏断层显象有明显可逆心肌缺损病例，７７．８％（２１／２７）术后心肌缺血消失或改善，２２．２％（６／２７）心肌缺血无改善或缺血范围扩大，其中５例经冠状动脉造影证实原有扩张部位再狭窄。结论多巴酚丁胺９９ｍ锝－ＭＩＢＩ心肌显象可用于评价冠心病介入性治疗的效果，在随访中可发现再狭窄，进一步指导治疗     

血液动力学方法治疗犬脑血管痉挛的实验研究

采用不同的血液动力学方法，对犬网膜下腔出血后引起的症状性脑血管痉挛进行治疗，我们发现：（１）等容称释加胞二磷胆碱和多巴酚丁胺疗法与人工扩容疗法疗效相同，但与等容稀释加胞二磷胆碱疗法相比，疗效有显著性差异，前者尤其知于扩容稀释禁忌证的病人；（２）稀释剂中加入胞二磷胆碱，可使红细胞变形能力半加，改善脑微循环（３）大剂量应用多巴胺升压，部分病例可使ＣＶＳ加重，临床应慎用。     

The effects of beta blockade on dopamine and dobutamine induced hypokalaemia in dogs

The effect of beta₁ and beta₂ blockade on dopamine and dobutamine induced hypokalaemia was investigated in dogs. Arterial plasma potassium was continuously monitored using a potassium-sensitive electrode sited in the abdominal aorta. Dopamine and dobutamine were infused at 15g kg^-1 min^-1 into animals pre-treated with atenolol (0.5 mg kg^-1) or ICI 118551 (0.5 mg kg^-1) and the potassium changes compared to those seen in control animals. The inotrope infusions caused a small and transient rise in plasma potassium (p<0.05) followed by a more profound hypokalaemia (p<0.05) sustained for the duration of the infusion. The potassium falls in the control animals were similar to those in the beta₁ and beta₂ blockade groups. The results suggest that beta₂ receptor stimulation cannot alone be responsible for dopamine and dobutamine induced hypokalaemia and a multiple receptor activation is postulated.M. Smith and H.F. Drake were supported by a grant from the Sir Jules Thorn Charitable Trust