保留二尖瓣后瓣下结构的二尖瓣置换术对左室构型及功能的影响

目的 评价保留二尖瓣后瓣下结构的二尖瓣置换术对左室构型及功能的影响.方法 选择因慢性风湿性心瓣膜病而行二尖瓣置换术(MVR)者79例,其中保留二尖瓣后瓣下结构组(MVRP)40例,不保留二尖瓣后瓣下结构组(MVRNP)39例,再根据病因不同分为二尖瓣狭窄(MS)组29例(MVRP 14例,MVRNP 15例),二尖瓣关闭不全(MI)组27例(MVRP 15例,MVRNP 12例)和双瓣置换术(DVR)组23例(MVRP 11例,MVRNP 12例).分别于术前、术后7 d和3月三维超声测量左房面积(LAA)、左室短轴缩短率(FS)、左室舒张期末容积(LVEDV)及收缩期末容积(LVESV),并计算左室射血分数(LVEF).结果 术后3月,MVRP组MI及DVR患者FS、LVESV、LVEF、LAA及LVEDV优于MVRNP组(P＜0.05);两组MS患者差别无统计学意义(P＞0.05); MVRP组左室构型呈椭圆形,MVRNP组呈偏心形或圆形.结论 与不保留二尖瓣后瓣下结构的MVR术比较,保留二尖瓣后瓣瓣下结构的MVR术对于MI、DVR患者更有利于改善左室构型及左室功能.     

蛙心期前收缩与代偿间歇实验技术改进

机能实验教学是医学实验教学中一个非常重要环节,开展综合性实验、创新性实验是机能实验教学中重要的内容,培养学生创新能力是实验教学改革的宗旨。将张力性实验和生物电实验综合一起开设,即蛙心期前收缩与代偿间歇和蛙心电图实验有机结合开设,进行同步记录实验结果,通过心电图与早博图形进行分析,对心脏疾病诊断治疗预后等进行评价,在临床上具有实用价值。     

The relationship between vascular wall shear stress and flow-mediated dilation: endothelial function assessed by phase-contrast magnetic resonance angiography

OBJECTIVES

We sought: 1) to investigate the relationship between vascular wall shear stress and flow-mediated dilation (FMD) in humans, and 2) to investigate whether this relationship could explain why FMD is greater in small arteries.

BACKGROUND

Arterial wall shear stress (WSS) is considered to be the primary stimulus for the endothelial-dependent FMD response. However, the relationship between WSS and FMD has not been investigated in humans. Furthermore, FMD is greater in small arteries, though the reasons for this phenomenon are unclear.

METHODS

Using phase-contrast magnetic resonance angiography (PMRCA), we measured hyperemic WSS and FMD in 18 healthy volunteers. Peak systolic WSS was calculated assuming a blunted parabolic velocity profile. Diameter by PCMRA and by ultrasound was compared in nine subjects.

RESULTS

Flow-mediated dilation was linearly proportional to hyperemic peak systolic WSS (r = 0.79, P = 0.0001). Flow-mediated dilation was inversely related to baseline diameter (r = 0.62, P = 0.006), but the hyperemic peak WSS stimulus was also inversely related to baseline diameter (r = 0.47, P = 0.049). Phase-contrast magnetic resonance angiography and ultrasound diameters were compared in nine subjects and correlated well (r = 0.84, p < 0.0001), but diameter by PCMRA was greater (4.1 ± 0.7 mm vs. 3.7 ± 0.5 mm, P = 0.009).

CONCLUSIONS

Arterial FMD is linearly proportional to peak hyperemic WSS in normal subjects. Thus, the endothelial response is linearly proportional to the stimulus. Furthermore, the greater FMD response in small arteries is accounted for, at least partially, by a greater hyperemic WSS stimulus in small arteries. By allowing the calculation of vascular WSS, which is the stimulus for FMD, and by imaging a fixed arterial cross-section, thus reducing operator dependence, PCMRA enhances the assessment of vascular endothelial function.     

大鼠心脏体外灌流过程舒缩功能与流量变化

目的 观察大鼠体外心脏灌流150min过程心率、舒缩能力、冠脉流量的变化。方法 Langendorff法灌流大鼠体外心脏，张力、记滴换能器分别采集心脏舒缩力、冠脉流量液滴信号，生物机能实验系统检测心率、心肌收缩幅度与最大收缩速度(dp／dtmax)、心肌舒张力、最大舒张速度(-dp／dtmax)、冠脉流出液的滴数。结果 大鼠体外心脏灌流150min过程心肌张力呈下降性变化，心率、收缩幅度、最大收缩速度、最大舒张速度、冠脉流量稳定120min，之后呈下降性变化。结论 大鼠心脏体外灌流时舒缩功能、冠脉流量可稳定2h。     

Changes in Morphology of the Paced QRS Complex Related to Atrial Contraction

A patient with 2:1 AV block underwent temporary ventricuJar pacing. AU the paced stimuli resuited in ventricular capture, but a marked variability in morphology of the paced QRS complexes occurred. Two different types of paced QRS complex (labeled A and B) were recognized. Type B complexes were manifest only when the pacing stimulus was preceded hy a sinus P wave within a time interval ranging from 0.15 to 0.52 sec. The P wave-induced changes in morphology of the paced QRS complexes were interpreted as due to displacement of the pacing ventricular lead caused by atrial systole.     

煤矿工人心脏储备无创性指标的调查研究

目的　为了获得煤矿工人心脏储备指标的数据。方法　 2 6名煤矿工人和 2 7名教职员纳入该调查研究。不同运动负荷下运动后心率对安静时心率增加的相应倍数定义为心率变化趋势 (HRCT) ;不同运动负荷下运动后第一心音幅值 (S1)对安静时S1幅值增加的相应倍数定义为心力变化趋势 (CCCT) ;完成规定的运动量的 1/4所得CCCT记为CCCT( 1/4 ) ;舒张期 /收缩期时限比值 (D/S)作为心脏舒张期自身供血时限的一个指标。结果　该组煤矿工人和对照组的 (D/S)分别为 1.96± 0 .3和 1.70± 0 .2 2 ,数据间的差异显著 (P <0 .0 1)。S1幅值、心率在运动试验中的变化方向与传统指标心率 -收缩压积在运动试验中的变化方向一致 ,煤矿工人、对照组以及所有受试者的S1幅值运动前后的差异都显著 (P <0 .0 1)。结论　通过体力劳动对心脏的效应 ,延长D/S比值 ,能使心脏舒张期自身供血时限更加充分 ;可以用心肌收缩能力变化趋势来无创地评估体力劳动者的心力储备。     

多虑平辅助治疗冠心病合并早搏的临床观察

目的观察多虑平辅助治疗冠心病合并早搏的临床疗效。方法将92例冠心病合并早搏患者随机分为2组,对照组(45例)予以阿司匹林、血管紧张素转换酶抑制剂或血管紧张素Ⅱ受体拮抗剂、他汀类、美托洛尔等治疗;治疗组(47例)在对照组用药的基础上加服多虑平。2组疗程均为4周,观察2组治疗前后的临床症状、心电图、24小时动态心电图及药物不良反应等变化。结果 2组治疗后临床症状均有明显改善(P<0.05或P<0.01),且治疗组胸痛、胸闷、心悸和失眠等症状改善较对照组更显著(P<0.05);治疗组临床症状总有效率(97.9%)优于对照组(71.1%),差异有统计学意义(P<0.01);24h动态心电图显示2组室性早搏、房性早搏和交界性早搏治疗后均明显改善(P<0.05或P<0.01),且治疗组改善更显著(P<0.01);治疗组早搏改善总有效率(室性早搏88.9%、房性早搏93.8%、交界性早搏92.3%)优于对照组(分别为58.8%、60.0%和61.5%),差异有统计学意义(P<0.05)。结论多虑平辅助治疗冠心病合并早搏疗效好,不良反应少,安全性高。