多普勒超声与同步心电图测定正常人左室收缩期时相的方法学研究

探讨以多普勒超声结合同步心电图定义左室收缩期时相的可行性。采用多普勒超声与同步心电图同时显示主动脉瓣口血流频谱及心电图的波形 ,测定 13例正常人左室收缩期各时相的时间与二维容积参数 ,比较常规法与多普勒超声法的测值之间差异 ;分析两种方法测值之间相关性和一致性。结果 :两种方法测量的左室收缩末期的时间无统计学差异 (P>0 .0 5 ) ,两者具有高度线性相关关系 (r=0 .91,P<0 .0 1)。 Bland- Altm an分析两种方法测值一致性良好 ;两种方法测量的左室收缩末期的容积无统计学差异 (P>0 .0 5 ) ,两者具有高度线性相关关系 (r=0 .97,P<0 .0 1)。两种方法测量的容积一致性良好 ;多普勒法测量的左室等容收缩末期的容积和常规法测量的左室舒张末期的容积经比较无统计学差异 (p>0 .0 5 ) ,两者具有高度线性相关关系 (r=0 .98,P<0 .0 1)。多普勒法测量左室等容收缩末期容积与常规法测量左室舒张末期容积一致性良好。多普勒超声结合同步心电图确定左室收缩期时相的方法是可行的 ,并与常规法具有相互替代性。     

脓毒症心肌损伤后心脏舒缩功能的动态变化

目的 探讨心脏舒张、收缩功能和心肌损伤指标对脓毒症患者动态变化和预后判断的作用。 方法 收集脓毒症患者70 例。根据28 d 的预后分为生存组和死亡组。分别于入重症医学科（ICU）第1 和3 天应用床旁心脏超声测量二尖瓣舒张早期充盈峰速度E 峰（E）与舒张晚期充盈峰速度A 峰（A）、二 尖瓣环舒张早期速度（e’）的比值,将E/e’及E/A 作为评估左心室舒张功能的指标;测量左心室射血分 数（LVEF）作为评估左心室收缩功能的指标。监测第1 和3 天心肌损伤标志物肌钙蛋白（cTnI）及肌酸激 酶同工酶（CK-MB）水平。通过Logistic 回归方法,对可能影响脓毒症预后的危险因素进行分析。结果 两 组患者于入ICU 第3 天的E/e’高于第1 天（P <0.05）,LVEF 低于第1 天（P <0.05）;死亡组第1 和3 天 的E/e’高于生存组（P <0.05）。两组第3 天的cTnI、CK-MB 高于第1 天（P <0.05）,死亡组第3 天的 cTnI 高于生存组（P <0.05）。Logistic 回归分析显示,E/e’[Ol ^ R=1.534,（95% CI ：1.116,1.982）,P =0.003]、 cTnI[Ol ^ R=1.120,（95% CI ：0.907,1.432）,P =0.039] 是影响脓毒症患者28 d 预后的危险因素。结论 脓毒症 患者存在心肌损伤,心脏舒张及收缩功能发生了动态变化,且高死亡风险脓毒症患者心脏舒缩功能及心肌损 伤明显加重。E/e’、cTnI 能预测脓毒症患者的预后。     

Estimates of systolic and diastolic myocardial blood flow by dynamic contrast‐enhanced MRI

Myocardial blood flow varies during the cardiac cycle in response to pulsatile changes in epicardial circulation and cyclical variation in myocardial tension. First‐pass assessment of myocardial perfusion by dynamic contrast‐enhanced MRI is one of the most challenging applications of MRI because of the spatial and temporal constraints imposed by the cardiac physiology and the nature of dynamic contrast‐enhanced MRI signal collection. Here, we describe a dynamic contrast‐enhanced MRI method for simultaneous assessment of systolic and diastolic myocardial blood flow. The feasibility of this method was demonstrated in a study of 17 healthy volunteers at rest and under adenosine‐induced vasodilatory stress. We found that myocardial blood flow was independent of the cardiac phase at rest. However, under adenosine‐induced hyperemia, myocardial blood flow and myocardial perfusion reserve were significantly higher in diastole than in systole. Furthermore, the transmural distribution of myocardial blood flow and myocardial perfusion reserve was cardiac phase dependent, with a reversal of the typical subendocardial to subepicardial myocardial blood flow gradient in systole, but not diastole, under stress. The observed difference between systolic and diastolic myocardial blood flow must be taken into account when assessing myocardial blood flow using dynamic contrast‐enhanced MRI. Furthermore, targeted assessment of systolic or diastolic perfusion using dynamic contrast‐enhanced MRI may provide novel insights into the pathophysiology of ischemic and microvascular heart disease. Magn Reson Med, 2010. © 2010 Wiley‐Liss, Inc.     

实时三平面组织同步显像评价正常人左心室内心肌收缩的同步性

目的应用实时三平面组织同步显像(TSI)技术评价正常人左心室内心肌收缩的同步性。方法应用实时三平面TSI技术同步采集20例健康志愿者心尖4腔观、2腔观及左室长轴观图像,脱机后进行后处理分析:(1)创建TSI彩色编码表示的左心室表面模型半定量反映心肌节段达峰时间(TTP);(2)定量测量3个心尖切面观左心室6个基底段和6个中间段TTP,并将各测值进行比较。结果 (1)TSI表面模型显示左心室各心肌节段彩色编码多为均匀一致的绿色,少数心尖段为黄色或红色。(2)左心室各心肌节段TTP差异均无显著性意义(均P>0.05)。结论正常人左心室内心肌收缩具有同步性;TSI技术可对心肌收缩的同步性作直观、定量地评价。     

速度向量成像技术对左室舒张功能的评价

【摘要】 目的 探讨速度向量成像（VVI）技术评价左室舒张功能的可行性。材料与方法 选取左室舒张功能减低患者61例和正常对照40例,应用VVI技术测定二尖瓣环前壁、下壁、侧壁、间隔4个位点的舒张早期、晚期运动速度（Ve、Va）及其比值（Ve/Va）、舒张早期、晚期应变率(SRe、SRa)及其比值(SRe/SRa),并计算各位点的平均值。结果 左室舒张功能减低组二尖瓣环各位点Ve、SRe、Ve/Va、SRe/SRa均低于对照组, Va、SRa均高于对照组（P<0.001）。结论 速度向量成像技术可用于二尖瓣环运动的定量分析,可作为评价左室舒张功能的一种新方法。     

Effect of reduced total blood volume on left ventricular volumes and kinetics in type 2 diabetes

Aim: Although impaired left ventricular (LV) diastolic function is commonly observed in patients with type 2 diabetes, it remains unclear whether the impairment is caused by altered LV relaxation or changes in LV preload. The purpose of this study was to examine the influence of LV function and LV loading conditions on stroke volume in men with type 2 diabetes. Methods: Cardiac magnetic resonance imaging scans were performed in eight men with type 2 diabetes and 11 non-diabetic men matched for age, weight and physical activity level. Total blood volume was determined with the Evans blue dye dilution technique. Results: End-diastolic volume (EDV), the ratio of peak early to late mitral inflow velocity (E/A) and stroke volume were lower in men with type 2 diabetes than in non-diabetic individuals. Peak filling rate and peak ejection rate were not different between diabetic and non-diabetic individuals; however, men with type 2 diabetes had proportionally longer systolic duration than non-diabetic individuals. Heart rate was higher and total blood volume was lower in men with type 2 diabetes. The lower total blood volume was correlated with a lower EDV in men with type 2 diabetes. Conclusions: Men with type 2 diabetes have an altered cardiac cycle and lower end-diastolic and stroke volume. A lower total blood volume and higher heart rate in men with type 2 diabetes suggest that changes in LV preload, independent of changes in LV relaxation or contractility, influence LV diastolic filling and stroke volume in this population.     

Echocardiographic and electrocardiographic study of the normal kangaroo heart

Abstract Healthy kangaroos are prone to sudden death. To investigate possible causes of this phenomenon, echocardiographic and electrocardiographic studies were conducted in seven healthy sedated (intramuscular ketamine 20 mg/kg, xylazine 2 mg/kg) kangaroos aged 1.5–5 years weighing 5.5–48 kg. As in human hypertrophic cardiomyopathy, kangaroos showed relative left ventricular hypertrophy measured as a ratio of (internal left ventricular end-diastolic diameter)/(septal + posterior wall thickness): 1.7 (SD 0.2) in kangaroos and 1.3 (SD 0.4) in hypertrophic cardiomyopathy cf 2.6 (SD 0.6) in normal man (p < 0.001 respectively). Peak left ventricular diastolic filling velocity was smaller in kangaroos (2.6 (SD 0.3)/sec) and hypertrophic cardiomyopathy (3.3 (SD 0.7)/sec) than in normal man (4.1 (SD 1.0)/sec) (p <0.01, p <0.05). The end of T wave occurred earlier than the closing of aortic valve. Corrected QT interval (0.20 (SD 0.02) sec) was shorter than the normal value for man (0.34–0.40 sec). In conclusion, kangaroos have cardiac hypertrophy of unknown aetiology, with impaired diastolic function, as in non-obstructive hypertrophic cardiomyopathy patients. Corrected QT interval was short. These echocardiographic and electrocardiographic findings may explain the mechanism of sudden death in kangaroos, a species which may be used as an experimental model of non-obstructive hypertrophic cardiomyopathy in man.     

3-Dimensional Echocardiographic Analysis of the Tricuspid Annulus Provides New Insights Into Tricuspid Valve Geometry and Dynamics

Objectives

The authors used transthoracic 3-dimensional transthoracic echocardiography (3DE) to characterize tricuspid annulus (TA) geometry and dynamics in healthy volunteers.