犬急性心肌梗死早期冠状动脉旁路移植术对左室壁运动的影响

目的 探讨犬急性心肌梗死早期冠状动脉旁路移植术对室壁运动的影响及其在唤醒冬眠心肌中的意义.方法 结扎犬冠状动脉前降支制备心肌梗死模型(30只).按手术日期随机分组,分别在心肌梗死后1、2、4、6周行冠状动脉旁路移植术作为实验组,其中第2周4只,其余每组6只;对每个实验组分别设立心肌梗死对照组(不进行冠状动脉旁路移植术),每组2只.实验组在冠状动脉旁路移植术前及冠状动脉旁路移植术8周后开胸利用多巴酚丁胺超声负荷试验结合组织多普勒成像技术标记冬眠心肌,并测定室壁运动记分;对照组在相同时间点同样的方法标记冬眠心肌并测定室壁运动记分.每只犬处死后分别测定心肌梗死面积.结果 每个实验组各存活4只,对照组均存活.1、2周实验组较4、6周实验组及对照组梗死区心肌室壁运动记分的变化明显减小(0.03±0.06,0.05 ±0.09,0.23 ±0.08,0.27±0.06,0.32 ±0.05,P＜0.05),所有实验组较对照组心肌室壁运动记分的变化明显减小(1.195±0.09,1.25±0.18,1.30±0.18,1.36 ±0.11,1.65 ±0.17,P＜0.05),所有实验组较对照组唤醒更多的冬眠心肌(0.27 ±0.12,0.22±0.04,0.31±0.09,0.23±0.03,0.03 ±0.04,P＜0.05).1、2周实验组较4、6周实验组及对照组心肌梗死范围明显减小[(20.75±2.63)％,(21.25±2.5)％,(27.25±1.71)％,(27.75±2.22)％,(26.50±0.71)％,(29.00±1.41)％,(27.00±1.41)％,(28.50±0.71)％,P＜0.05)].结论 犬急性心肌梗死早期冠状动脉旁路移植可以明显改善心肌室壁运动,唤醒更多的冬眠心肌,尤其2周内行冠状动脉旁路移植术可以最大限度地减少梗死心肌对室壁运动的影响,并可以减少心肌梗死范围.     

Unilateral changes of sympathetic tone to the heart impair left ventricular function

Background. Different regions within the left ventricle are preferentially supplied by the left or right sympathetic system. In order to characterize different influences of left vs right sympathetic lateralization on LV function, haemodynamic effects of right and left stellate ganglion stimulations (RSGS and LSGS) as well as a right sympathetic block (RSB) were compared. Methods. Seven α-chloralose anaesthetized open chest dogs were instrumented for measurement of LV pressure (tip manometers) and regional LV wall thickness (WT, sonomicrometry) in the ante-ro-apical wall (AW, innervated by right stellate ganglion) and posterobasal wall (PW, left stellate ganglion). Timing of regional myocardial wall motion was evaluated by the phase of the first Fourier transform of the WT signals, LV asynchrony by the phase difference (ψ) between both regions, and LV diastolic function by the time constant of isovolumic relaxation (τ). Measurements were performed before and after RSB (5 ml of lidocaine 1%); in 6 dogs of this group, RSGS and LSGS (4 V, 0.2 ms, 20 Hz) were performed before RSB. In order to investigate a regional inotropic stimulation without systemic effect, 6 additional dogs received intracoronary noradrenaline injections (NIC, 0.25 μg) into the left circumflex artery perfused myocardium. Results. LSGS and NIC led to an earlier PW-motion within the cardiac cycle (phase reduction by 40.0±15.0° (SEM) and 55.5±11. 2°) and RSGS induced an earlier AW-motion (by 33.7±15.2°). After RSB, AW-motion was delayed (38.1±9.2°). The consequence was an asynchronous wall motion pattern after all interventions (change in ψ: LSGS -64.7±18.7°, RSGS 41.1±15.7°, NIC -74.5±17.4°, RSB -52.6±14.6°), and a prolonged relaxation (T increase: RSGS 9.4±1.9, NIC 8.3±1.5, RSB 3.7±0.8 ms). Conclusion. Unilateral increases as well as decreases of sympathetic tone to the heart result in an asynchronous wall motion pattern and an impaired LV relaxation.     

Rapid reversal of global left ventricular dysfunction after accidental injection of 0.75 mg epinephrine in a 20-year-old patient

We report an accidental injection of epinephrine before spinal anaesthesia in a 20-year-old patient who subsequently developed immediate myocardial ischemia and global left ventricular dysfunction (ejection fraction of 20%). Hemodynamic status dramatically improved after nitroglycerin, calcium antagonists, acetyl salicylic acid and unfractionated heparin injections. Over 24 h, patient's ejection fraction fully recovered without kinetic abnormality.     

异丙酚对大鼠离体心脏左右心室功能的影响

目的 研究三种浓度的异丙酚对离体大鼠左右心室收缩功能的影响。方法 雄性SD大鼠10只,经Langendorff离体心脏恒压灌注,依次梯度输入含有异丙酚1、3和10ug/ml的灌注液。通过心室内的乳胶水囊经换能器连于MacLab Instruments和Macintosh微机系统,观察给药前后以及不同浓度丙酚对左右心室等容收缩时压力和速度指标的影响。结果 10ug/ml的异丙酚提高了左右心室的发展压,降低了舒张末期压;同时回忆了左右心室收缩和舒张的速度;增加了冠脉灌流量。结论 异 保护心肌舒缩功能的作用,不直接抑制左右心室的内在收缩性,高浓度时有扩张冠脉的作用。     

Development of left ventricular hypertrophy in a novel porcine model of mitral regurgitation

Objectives. We aimed to develop a porcine model for chronic nonischemic mitral regurgitation (MR) to investigate left ventricular (LV) enlargement and eccentric hypertrophy. Design. Nonischemic MR was induced in 30 pigs by open-chest immobilization of the posterior mitral leaflet by transannular traction sutures that where applied in transmyocardial fashion. A sham operated control group (n = 13) was included. Echocardiographic LV size and heart weight assessed at euthanasia were used to evaluate the development of LV enlargement and eccentric hypertrophy after 8 weeks follow-up. Results. Eight pigs died and seven were excluded due to mediastinal infection (n = 2) or failure to produce MR (n = 5). Thus, 28 pigs were included and were divided into three groups: controls (n = 12), mild MR (mMR; n = 10), and moderate to severe MR (sMR; n = 6). The change in LV internal diameter in diastole (LVIDd) from baseline to follow-up was significantly higher in the sMR group compared to that of the control group (P = 0.0017). Furthermore, LV weight was significantly increased in the mMR (P = 0.047) and the sMR (P = 0.0087) groups compared to that of the control group. Conclusions. A new model for chronic moderate to severe nonischemic MR with development of LV enlargement and eccentric hypertrophy within 8 weeks has been established in pigs.     

A comparison of the effects of fentanyl and propofol on left ventricular contractility during myocardial stunning

Background : The intravenous anaesthetic propofol has been shown to possess free radical scavenging activity and calcium channel blocking effects in a number of in vitro models. We decided to compare the effects of propofol with those of fentanyl on myocardial contractility during and after ischaemia to determine whether propofol could protect the heart and improve recovery of ventricular contractile function in open-chested dogs.
Methods : Twenty adult beagles were acutely instrumented, under halothane anaesthesia, to measure ECG; aortic, left ventricular pressures; cardiac output; coronary flow; and segmental lengths in the regions perfused by the left anterior and left circumflex coronary arteries. After surgery and a stabilisation period halothane anaesthesia was terminated and fentanyl (100 μg. kg^-1 bolus followed by 2 μ.kg^-1·min^-1 infusion; n=10) or propofol (5 mg. kg^-1 bolus followed by 0.3 mg· kg^-1 min^-1 infusion; n=10) anaesthesia commenced. After a stabilisation period the LAD coronary artery was occluded for 10 min and then reperfused for 3 h. Measurements were taken throughout the protocol.
Results : We found no significant difference in recovery of contractile function between propofol and fentanyl as assessed by normalised preload recruitable work area (50±10 vs 47±16%), normalised systolic shortening (36±12 vs 48±14%) and peak left ventricular dP/dt (1665±276 vs 1846±151 mmHg.s^-1) at the end of reperfusion.
Conclusion : We conclude that at the concentration used in this study propofol shows no improvement in contractility during "stunning" when compared to fentanyl.     

硫化氢后处理对大鼠心肌缺血再灌注时左心室收缩功能的影响

目的 探讨硫化氢后处理对大鼠心肌缺血再灌注时左心室收缩功能的影响.方法 实验一成年雄性SD大鼠,体重200～250 g,采用Langendorff装置建立离体心脏灌注模型.取离体灌注模型制备成功的心脏40个,随机分为5组(n=8):对照组(C组)、缺血再灌注组(IR组)和硫氢化钠1、10、100 μmol/L后处理组(SP1组、SP10组、SP100组).平衡灌注20 min后,C组继续灌注K-H液100 min;IR组灌注ST.Thomas停跳液10 ml/kg后停灌40 min,恢复K-H液灌注60 min;SP1组、SP10组、SP100组全心缺血40 min,于再灌注前灌注含1、10、100 μmol/L硫氢化钠的K-H液2 min,然后恢复K-H液灌注60 min.于平衡灌注末和再灌注60 min时,记录左室发展压(LVDP)、左心室发展压最大上升速率(+dp/dtmax)和左心室发展压最大下降速率(-dp/dtmax).实验二成年雄性SD大鼠,体重200～250 g,分离心肌细胞,加入培养皿中,放入95%O2-5%CO2培养箱中培养4 h.取64皿细胞,随机分为4组(n=16):对照组(C组)、缺氧复氧组(HR组)、硫化氢后处理组(SP组)和缺氧后处理组(HP组).C组继续于95%O2-5%CO2培养箱中培养2 h;HR组于95%N3-5%CO2培养箱中缺氧1 h,然后于95%O2-5%CO2培养箱中复氧1 h;SP组于95%N2-5%CO2培养箱中缺氧1 h,加入硫氢化钠10μmol/L孵育2 min,然后于95%O2-5%CO2培养箱中复氧1 h;HP组于95%N2-5%CO2培养箱中缺氧1 h,然后复氧3 min,缺氧3 min,重复3次,再于95%O2-5%CO2培养箱中复氧1 h.测定线粒体膜电位和F-肌动蛋白的表达.结果 实验一与C组比较,再灌注60 min时IR组LVDP和±dp/dp/dtmax降低(P＜0.05),SP1组、SP10组和SP100组LVDP和±dp/dtmax差异无统计学意义(P＞0.05);与IR组比较,SP1组、SP10组和SP100组LVDP和±dp/dtmax升高(P＜0.05);SP1组、SP10组和SP100组间LVDP和±dp/dtmax比较差异无统计学意义(P＞0.05).实验二与C组比较,HR组和HP组线粒体膜电位降低,HR组、SP组和HP组F-肌动蛋白表达上调(P＜0.05);与HR组比较,SP组和HP组线粒体膜电位升高,F-肌动蛋白表达上调(P＜0.05);SP组和HP组间线粒体膜电位和F-肌动蛋白表达比较差异无统计学意义(P＞0.05).结论硫化氢后处理可改善大鼠心肌缺血再灌注时左心室收缩功能,与其稳定心肌细胞线粒体膜电位和促进F-肌动蛋白聚集有关.     

骨髓细胞移植对梗死区心肌基本结构及左心室功能的影响

目的 探讨骨髓细胞移植对梗死区心肌基本结构及左心室功能的影响。方法 骨髓细胞注射人心肌梗死区域，1、2、4、8周后取心肌标本，组织切片染色观察组织结构；术后1、2、4、8周通过微机生物信号记录分析系统测定左心室功能指标。结果 移植组梗死区心肌观察到带荧光的骨髓细胞，部分已分化成肌源性细胞，电子显微镜观察到不同分化阶段的新生心肌细胞，并与成熟心肌细胞以闰盘相联接。HE染色显示对照组梗死区结构紊乱，而移植组梗死区内细胞呈有序排列；VG染色显示移植组胶原纤维融合较少，排列基本处于有序状态。移植组左心室功能的恢复明显优于对照组，且其恢复随时间的延长而增加。结论 骨髓细胞移植后对梗死心肌的基本结构起到了保护作用，并可促进左心室功能的恢复。     

七氟烷对体外循环冠状动脉旁路移植术患者左心室功能的影响

目的 评价七氟烷对体外循环(CPB)冠状动脉旁路移植术(CABG)患者左心室功能的影响.方法 择期CPB下行CABG的冠心病患者35例,男性30例,女性5例,年龄53～75岁,身高150～183 cm,体重46～100 kg,AsAⅡ或Ⅲ级,七氟烷分为冠脉搭桥前后2个阶段给药,分别为气管插管后至锯胸骨前和关闭胸腔至手术结束前,CPB期间停止吸入七氟烷.七氟烷呼气末浓度相当于1 MAC.围术期行食管超声心动图(TEE)检查,于锯胸骨前未吸入七氟烷(T_1)、吸入5 min(T_2)、15 min(T_3)、关闭胸腔后未吸入七氟烷(T_4)、吸入5 min(T_5)、15 min(T_6)时记录平均动脉压(MAP)和TEE监测指标:E波、A波、S波.D波和AR波的峰值、心指数(CI)、左室短轴缩短率(FS)、左室射血分数(LVEF),左心室舒张早期血流播散速度(Vp),计算E波与A波峰值比(E/A)、S波与D波峰值比(S/D) 和E波与Vp的比值(E/Vp).结果 与T_1时比较,T_(2,3)时MAP降低,T_3时LVEF、FS和CI降低,T_4时HR、LVEF、FS、CI升高,.E波:A波、S波、D波和AR波的峰值升高(P<0.05或0.01);与T_4时比较,T_(5,6)时MAP降低,T_6时LVEF、FS和CI降低(P<0.05或0.01).结论 呼气末浓度相当于1 MAc的七氟烷可明显抑制CPB下CABG患者左心室收缩功能,但对舒张功能无明显影响.     

Effects of direct mechanical ventricular assistance on regional myocardial function in an animal model of acute heart failure

Direct mechanical ventricular assistance (DMVA) improves hemodynamics in failing hearts without complications associated with a blood/device interface. Epicardial Doppler displacement transducers provide exact measurements of tissue displacement and regional myocardial function (RMF). An in vivo porcine model of acute heart failure was used to examine the effects of DMVA on RMF, which have not been reported before. In 8 anesthetized pigs cardiac output (CO), left ventricular pressure (LVP), aortic blood pressure (BP), systolic contractility (dp/dt max), and systolic wall thickening fraction (WT%) were measured. A multichamber pump system (IMPS) surrounding the left ventricle was implanted and the measurements were repeated. Then acute heart failure was induced by beta-blockade, resulting in a decline of all measured parameters to more than 30% compared to baseline values. In the further course of the experiment, repeated measurements were taken at several intervals with and without DMVA by the implanted device. The IMPS implantation caused no significant hemodynamic changes. Under conditions of acute heart failure DMVA improved LVP (46 +/- 7 to 81 +/- 9 mm Hg), dp/dt max (532 +/- 207 to 744 +/- 361 mm Hg/s), CO (1.5 +/- 0.1 to 1.9 +/- 0.5 L/min) and WT% (19 +/- 7% to 32 +/- 8%). Left ventricular myocardium not directly assisted by external pressure application showed improved regional myocardial function during DMVA. We conclude that DMVA is capable of improving hemodynamics due to extrinsic compression. It also enhances the remaining myocardial function of the failing heart, which might lead to myocardial recovery. These synergistic effects are considered responsible for the high efficiency shown by the IMPS in previous investigations.     

经主动脉瓣插管左心室辅助的研究

目的 探讨经主动脉瓣插管的左心室辅助方式应用于急性心力衰竭动物模型的可行性.方法 在6头猪的急性心力衰竭模型中,尝试经主动脉瓣插管的左心室辅助.并进行血流动力学及心脏超声指标的观察.结果 6头猪中有5头完成了实验.它们在血流动力学方面都显示急性心力衰竭状态的建立(P<0.05).心超指标未提示经主动脉瓣插管对主动脉瓣、二尖瓣及左心室功能的显著影响(P>0.05).在循环辅助下的血流动力学指标及部分生化指标也都较心衰状态有显著改善(P<0.05).心脏超声所示的左心室射血分数(LVEF)也有显著改善(P<0.05).结论 在急性心力衰竭模型建立后,经主动脉瓣的插管对瓣膜及左心室的功能未造成不良影响.这种循环辅助方式可以在短时间内改善急性心力衰竭的状态.     

Effect of simulated orchiopexy on spermatogenesis in the dog

The poor fertility after orchiopexy can be due either to the previously prolonged high abdominal temperature, to surgical trauma or to congenitally malformed or dissociated testis and epididymis. In order to test whether manipulation of the testis and the spermatic cord in juvenile dogs causes damage to the seminiferous epithelium after puberty, orchiopexy was performed stepwise in 31 normal young dogs. In four dogs, in which traction to the proper testis ligament or biopsy was carried out, a significantly lower relative testis weight was found, together with impaired differentiation of the seminiferous epithelium. From these experiments it was clear that surgical procedures in the inguinal and scrotal region do not necessarily affect the development of the seminiferous epithelium in the dog. However, trauma to the vaginal tunic seemed to be crucial, causing damage to the differentiation of the seminiferous epithelium.     

Total ligation of the left renal vein in the dog: an inappropriate model for varicocele

Induction of varicocele was attempted by ligation of the left renal vein (LRV) in male dogs (Group I). Before the operation and in the 4-month post-operative period, sperm count, sperm motility, and sperm morphology of Group I (n = 8) dogs were compared to sham operated animals (Group II, n = 5). Furthermore, haemodynamics as well as testicular and vascular morphology were studied. In Group I, changes in diameter and consistency of the spermatic cord were temporary. Semen quality was reduced significantly during the second month after ligation of the LRV, but improved thereafter. Haemodynamic studies revealed that LRV blood pressure was increased significantly in Group I dogs. An extensive venous collateral network replaced the occluded LRV. Retrograde blood flow in the left testicular vein (LTV) was observed only in the proximal part of the LTV of Group I dogs. In Group II dogs numerous pairs of sufficient valves prevented reflux into the LTV. Histological examination revealed that spermatogenesis was not impaired and that the left pampiniform plexus had not changed. The number of Leydig cells was decreased slightly in Group I dogs. Sufficient valves in the LTV prevented formation of a permanent varicocele.     

The effect of sodium concentration on myocardial viability in donor heart preservation using a nondepolarizing solution

This study examined the effect of different sodium concentrations in a nondepolarizing solution on myocardial viability and functional recovery of the canine donor heart. Isolated canine hearts were preserved for 6 h at 5°C, followed by normothermic reperfusion for 2 h. Dogs were divided into two groups of nine dogs each: group 1 received a nondepolarizing solution with 70mm Na⁺ and group 2 with 30mm Na⁺. The myocardial Ca²⁺ concentration at the end of preservation was significantly higher in group 1 than in group 2 and increased after reperfusion in both groups without any intergroup difference. Myocardial concentrations of ATP, ADP, and total adenine nucleotide at the end of reperfusion were significantly higher in group 1 than in group 2. Myocardial cyclic adenosine monophosphate concentration was significantly higher in group 1 than in group 2 at the end of both preservation and reperfusion. The myocardial cyclic guanosine monophosphate concentration in group 1 increased and was higher than in group 2 at the end of preservation, but had returned to normal levels by the end of reperfusion. However, it remained unchanged through preservation and reperfusion in group 2. The left ventricular systolic and diastolic function, assessed by pressurevolume relationship, was better in group 1 than in group 2. Mitochondrial ultrastructural changes were similar. These results suggest that a nondepolarizing solution containing 70mm Na⁺ provides better myocardial protection than a solution containing 30mm Na⁺.     

Effect of hypertonic saline solution on the left ventricular functions of isolated hearts from burned rats

Objective: To study the effect of hypertonic saline solution on the left ventricular functions of isolated hearts from Imrned rats. Methods: Thirty-six Wistar rats were used and divided into 4 groups: (1) normal hearts perfused with isotonic Krebs-Henseleit solution; ( 2 ) normal hearts perfused with Krebs-Henseleit solution which contained 215 mmoVL Na^ ; (3) hearts of rats suffered from 25% TBSA third degree burn and perfnsed with isotonic Krebs-Hensekit solution; (4) hearts of the burned rats perfused with Krebs-Henseleit solution which contained 215 mmol/L Na^ . The systolic and diastolic functions of the left ventricle were observed. Results: During perfusion, there were very short periods of decrease in heart systolic and diastolic functions at first, but they recovered very soon and even became stronger than normal both in the normal and burned rats.The systolic and diastolic functions of the hearts increased very siLmificantly when the perfusion solution was changed to isotonic solution from the hypertonic solutions. The effect of the hypertonic s.gline solution on the ventricular systolic and diastolic improvements was stronger in the hearts of the burned rats than that in the normal hearts. Conclusions: Hypertonic saline solution can directly affect myocardium and significantly improve the ventricular systolic and diastolic functions, especially in the hearts of the burned rats.     

Effect of pulsatile left ventricular assist system implantation on Doppler measurements of renal hemodynamics in patients with advanced heart failure

The effects of left ventricular assist system (LVAS) implantation on renal hemodynamics remains to be fully elucidated. We evaluated renal function and intrarenal blood flow in five advanced heart failure patients who had been supported with a Toyobo LVAS for bridge to heart transplantation. Renal function expressed as estimated glomerular filtration rate (eGFR) was calculated using the modified formula of Modification of Diet in Renal Disease. Mean blood velocities in the bilateral segmental arteries during systolic and diastolic perfusion were measured using duplex Doppler sonography, and renal vascular resistance (resistive index [RI]) of the segmental arteries was defined as (peak systolic velocity [PSV]-end-diastolic velocity [EDV])/PSV. All studies were performed before and after implantation (mean duration of support, 15.6±10.9 months). LVAS implantation significantly improved eGFR (42.7±7.9 to 64.1±16.3mL/min, P<0.05). Beat-by-beat measurements of heart rate did not change significantly. Mean PSV decreased significantly (38.2±8.9 to 28.3±2.2cm/s, P<0.05), and mean EDV increased significantly (8.3±3.2 to 11.3±1.3cm/s, P<0.05), and thus, mean RI was significantly improved (0.79±0.06 to 0.60±0.04, P<0.01). In conclusion, in advanced heart failure patients, pulsatile LVAS implantation is associated with improved renal function, and this improvement may be mediated in part through an improvement of intrarenal hemodynamics.     

帕瑞昔布钠对急性心肌梗死大鼠心功能的影响

目的 评价帕瑞昔布钠对急性心肌梗死大鼠心功能的影响.方法 成年雄性SD大鼠24只,体重230～250 g,随机分为3组(n=8):假手术组(S组)、急性心肌梗死组(AMI组)和帕瑞昔布钠组(P组).AMI组和P组采用结扎左冠状动脉前降支的方法制备大鼠急性心肌梗死模型,S组冠状动脉穿线但不结扎;24 h后P组腹腔注射帕瑞昔布钠8 mg/kg,1次/d,连续3 d,AMI组用生理盐水替代.术后第4天测定并记录左心室收缩压(LVSP)、左心室舒张末期压(LVEDP)、左心室收缩压最大上升速率(+dp/dtmax)和左心室收缩压最大下降速率(-dp/dtmax);采集颈总动脉血样3 ml,采用放射免疫法测定血浆血栓素A2(TXA2)和前列腺素I2(PGI2)的浓度,并计算PGI2/TXA2;采血后取左心室心肌组织,测定梗死面积,计算心肌梗死体积.结果 与S组比较,AMI组和P组LVSP、±dp/dtmax、血浆PGI2浓度和PGI2/TXA2降低,LVEDP和血浆TXA2浓度升高(P＜0.05).与AMI组比较,P组LVSP、±dp/dtmax、血浆PGI2浓度和PGI2/TXA2升高,LVEDP和血浆TXA2浓度降低(P＜0.05).AMI组和P组心肌梗死体积比较差异无统计学意义(P＞0.05).结论 帕瑞昔布钠可改善急性心肌梗死大鼠左心室功能,其机制与调节PGI2/TXA2相对平衡有关.