左心辅助不同插管途径对心肌氧代谢的影响

目的对左心辅助的两种插管引流途径(左心室引流与左心房引流)的氧代谢情况进行对比研究,为临床选择合适的引流途径提供实验依据。方法将12条犬随机分成两组,分别建立左心房-主动脉(LA组)和左心室-主动脉(LV组)的左心室辅助动物模型,并测定左心辅助后各时相的心率、冠状静脉窦血流量,计算冠状静脉窦的氧含量、冠状动静脉血氧含量差和心肌的耗氧量。结果两组心率在各时点差别无统计学意义(P>0.05);两组的心肌耗氧量、冠状静脉窦血流量和冠状动静脉血氧含量差辅助后均较辅助前显著降低;左心室引流途径对降低心肌耗氧量的作用比左心房引流更明显(P<0.01)。结论两种引流途径均能明显降低心肌的耗氧量,以左心室引流更为明显。     

浅低温体外循环冠脉搭桥手术中病人脑氧合的变化

心肺转流(CPB)体外循环心脏手术病人,术后中枢神经系统并发症高达2%～5%,其发生与脑栓塞及脑氧合失调有关。颈静脉球血氧饱和度可反映脑代谢的变化,常作为一种检测脑氧合平衡的指标[1]。因此我们观察了浅低温CPB冠脉搭桥手术中SjvO2及相关指标的变化,以探讨脑氧合的变化规律。1     

应用左心转流术的降主动脉瘤手术治疗

１９８２年５月～１９９３年５月期间共为３３例降主动脉瘤病人采用左心转流方法进行手术治疗。平均降主动脉阻断时间为１００±３５ｍｉｎ；转流过程中根据压力和容量负荷调节左房引流量和灌注流量。３１例行降主动脉瘤切除及人工血管置换，其中２例同时行肋间动脉移植；２例行降主动脉补片修补。全组手术死亡３例，占９％（３／３３）。作者认为左心转流损伤较小、操作方便，转流时采用氧合器做贮血器，有利于回收、贮存血液和调节温度。     

左心转流降主动脉瘤手术中致萎陷肺损伤因素的临床研究

为探讨左心转流降主动脉瘤手术中致萎陷肺出血的因素，作者对１４例手术中萎陷肺有不同程度出血（Ａ组）和１４例手术中无肺出血（Ｂ组）的临床资料进行了回顾性分析。结果表明：Ａ、Ｂ两组在转流量、上肢血压及ＣＶＰ存在显著性差异，而在年龄、体重、左心转流时间及主动脉阻断时间、瘤体大小及肺粘连等方面无明显区别，但两组均未测左房压。鉴于上述发现，作者在Ｃ组（８例）进行了前瞻性临床研究，即维持每分钟转流量３５±３．１ｍｌ／ｋｇ，通过调节左房引流控制左房压在０．６７～２．００ｋＰａ（５～１５ｍｍＨｇ），结果Ｃ组即无肺出血发生，也无明显肺组织病理学改变。作者认为左心转流降主动脉瘤手术期间维持转流量大于每分钟３０ｍｌ／ｋｇ，控制左房压在上述范围，可保证合适的肺循环和体循环血流动力学，防止萎陷肺损伤。     

体外循环中搏动和非搏动灌注对皮肤微循环自律运动的影响

关于体外循环期间应用搏动灌注的优点，一直有很大的争议。本实验旨在观察体外循环中搏动灌注和非搏动灌注对皮肤微循环自律运动和氧代谢的影响。观察对象是１５例心脏瓣膜病人。当病人温度平稳时，分别以２．４Ｌ·ｍｉｎ~（－１）／ｍ~２的流量进行搏动灌注和非搏动灌注。搏动灌注的参数为：基线３０％～４０％、脉宽４０％～５０％、脉冲频率６０次／ｍｉｎ。结果表明：搏动灌注和非搏动灌注对皮肤微循环血流量、微循环自律性运动频率、氧代谢的影响不明显。我们对这一现象进行了分析。并认为搏动灌注在临床应用中，由于多种因素的影响，其优越性难以体现。     

The Pulsatile Impeller Pump for Left Ventricular Assist

Abstract: Because of severe hemolysis, especially on producing pulsatile flow by changing the rotating speed of the impellers, the traditional centrifugal pump was rarely used for long-term support of the failing heart. We therefore developed a motor driven pulsatile implantable impeller pump. The pulsatility was achieved by changing the rotating speed via introducing a square waveform voltage into the motor coil. The impeller vane was designed to have both radial and axial curves according to the stream surface and stream lines to reduce the thrombosis and hemolysis. Nine calves weighing 80 to 100 kg were used. With the calves under endotracheal general anesthesia, left posterolateral thoracotomy was performed to connect the inflow tube with the left atrial appendage and to anastomose the outflow tube with the descending aorta. The calves usually awoke and stood up within hours after discontinuation of anesthetics. Within 7 days, continuous monitoring of electrocardiogram, systemic and pulmonary arterial pressures, and central venous pressure were performed to adjust the pump flow to 40% to 50% of the cardiac output. During the survival of 4 to 54 days (mean 16.3 ± 19.3 days with two calves surviving longer than 1 month), no significant deterioration of liver or renal function was noted. Because of bleeding, hemoglobin reduced from 11.4 ± 1.8 to 9.0 ± 1.3 g/dl, and the hematocrit decreased from 34.5 ± 4.7 to 26.7 ± 4.6%. No significant changes of free hemoglobin were noted. In our results, the device revealed competent pulsatile function without severe blood damage or organ dysfunction.     

Cardiac Autonomic Nervous Function During Long-Term Nonpulsatile Left Heart Bypass

We investigated the changes in cardiac autonomic nervous activities during long-term nonpulsatile left heart bypass (NLHB) by analyzing heart rate variability. A pulsatile ventricular assist device was installed in 3 goats, and pulsatile left heart bypass (PLHB) was conducted for 2 weeks. Then, NLHB was maintained for the following 4 weeks. The segmental data of the R-R intervals (R-Rs) was analyzed by maximum entropy spectral analysis. Changes in evaluated parameters from the last week of PLHB to the 4th week of NLHB were as follows: the mean R-Rs increased from 511 ms to 692 ms; the coefficient of variation of R-R increased from 10.2 to 14.1%; the power of the low frequency band (LF) increased from 747 ms2 to 2,855 ms2; the power of the high frequency band (HF) increased from 512 ms2 to 1,270 ms2; and the ratio of LF to HF increased from 2.6 to 6.5. These results indicated that the cardiac autonomic nervous activity, both sympathetic and parasympathetic, increased during long-term NLHB.     

Diminished Vasoconstrictive Function Caused by Long-Term Nonpulsatile Left Heart Bypass

We investigated the functional changes of the systemic vascular system due to prolonged nonpulsatile left heart bypass (NPLHB). Three adult goats underwent pulsatile left heart bypass (PLHB). Two weeks later the PLHB was changed to the NPLHB, which was conducted for 4 weeks. The aortic pulse pressure was 39 and 16 mm Hg during the PLHB and NPLHB, respectively. Systemic vascular resistance (SVR) and the plasma norepinephrine level were measured at the end of PLHB (PUL), and in the 1st, 2nd, 3rd, and 4th weeks of NPLHB (NP1w, NP2w, NP3w, and NP4w). At each point, 1 microg/kg norepinephrine was injected, and the elevation of the SVR (deltaSVR) was calculated. The SVR and the plasma norepinephrine level did not change significantly during the entire course. However, deltaSVR decreased during NPLHB and became significantly lower at NP3w and NP4w than that at PUL (NP3w: 839 +/- 164, NP4w: 746 +/- 268, and PUL: 1,239 +/- 324 dyne x s x cm(-5)). These results strongly indicated that prolonged NPLHB significantly diminished the constrictive function of the vascular system.     

异丙酚对体外循环后早期脑氧代谢的影响

目的观察异丙酚对体外循环(CPB)后早期脑氧代谢的影响. 方法 25例低温CPB下行瓣膜置换术患者,随机分成异丙酚(P)组和咪唑安定(M)组,分别于CPB前(T1)、复温5 min(T2)、CPB结束后15 min(T3)、 30 min(T4)和60 min(T5)观察SjO2、 CEO2、 Da-vO2, Da-vCO2和PH差等指标. 结果 P组SjO2在T1～T5均显著高于M组;T3时相SjO2<60%者P组仅1例患者,少于M组的5例(P<0.05);各组内Da-vO2在T2、T3均低于T1,P组于T4恢复至T1水平,M组需至T5才恢复至T1水平. 结论异丙酚对CPB后早期脑氧供需障碍有一定的改善作用.     

左心室射血分数与缩短分数对冠状动脉旁路移植术后室性心律失常的预测

目的　研究冠状动脉旁路移植术 (CABG)前左心室射血分数 (EF)和左心室缩短分数 (FS)对术后室性心律失常 (VA)预测的准确性。　方法　回顾性分析我院 1998～ 1999年度 CABG患者 30 0例 ,手术前、后定期用彩色超声心动图测 EF和 FS值 (面积长轴法 ) ,信号平均心电图测心室晚电位 (VL P) ,围术期监测心肌酶确定心肌缺血和围手术期心肌梗死 ,2 4小时 Holter及持续心电监测心律。　结果　术前心肌梗死、室壁瘤、VA和 VL P阳性者术后 EF、FS值明显减低 ,左心功能不全者 (L VD)术后 EF、FS值明显改善 ,L VD、VA、VL P阳性和室壁瘤患者术后 VA发生率明显高于其他患者。　结论　EF和 FS值是反映左心室收缩功能的敏感指标 ,FS较 EF更能准确地反映心脏收缩功能 ;术前 L VD者术后短期左心功能明显好转 ,获益最大 ,所以 L VD不应作为 CABG术的绝对禁忌证 ,相反是手术的相对适应证 ;EF≤ 0 .40和 /或 FS≤ 0 .2 4是预测术后 VA的独立指标 ;综合 L VD、VL P和室壁瘤等指标分析有助于提高对术后预测 VA的敏感度、特异度和准确度。     

Significant Left Ventricular Unloading with Transaortic Catheter Venting During Venoarterial Bypass

Abstract: Insufficient unloading of the left ventricle with blood stagnation is a main cause of unsuccessful left vcntricular (LV) recovery during percutaneous cardiopulmo-nary support (PCPS). The purpose of this investigation was to evaluate the effectiveness of transaortic catheter venting (TACV) for LV unloading. Six adult mongrel dogs (mean weight 16.3 kg, range 14–20 kg) underwent venoarterial bypass (VAB) with TACV. Bypass flow ranged from 0.8–1.2 L/min, and TACV flow ranged from 160–240 ml/min. In addition to monitoring the standard hemodynamic parameters, the slope of the LV end-systolic pressure-volume relation (Emax) during transient occlusion of the inferior vena cava, the slope of the LV end-systolic pressure-stroke-volume relation (Ea), the stroke work (SW). the LV pressure-volume area (PVA), and the slope of the SW end-diastolic volume relation. the preload recruitable stroke work (PRSW) were assessed by means of a microtip manometer and a conductance catheter. The LV contractility (Emax) and aortic elastance (Ea) were equivalent in the 2 groups with or without TACV (7.7 ± 1.1 versus 8.4 ± 1.5 mm Hg/ml and 8.2 ± 1.4 versus 7.6 ± 1.3 mm Hg/ml). Comparing the measurements for the baseline to those for VAB with TACV, the SW was significantly reduced, and the PVA/SW was increased by TACV (1,685 ± 309 versus 867 ± 188 ± 10^--⁴J, p < 0.05 and 1.32 ± 0.03 versus 1.58 ± 0.11, p < 0.05, respectively). Furthermore, the PRSW was gradually decreased from the baseline value to the value resulting from VAB with TACV (75 ± 8 versus 44 ± 3 ± 10^--⁴J/ml, p < 0.01). In comparison, the percent reduction of SW between VAB and VAB with TACV tended to he increased by TACV (23.2 5 7.2% versus 46.9 ± 7.7%, p = 0.05). These results suggest that TACV might reduce LV work (SW and PRSW) and might increase the LV energetic charge. In conclusion, TACV would be an adjunctive technique to VAB or PCPS for patients with LV failure.     

冠心病合并左室室壁瘤行冠状动脉旁路移植术未同期行左心室成形术的疗效分析

目的 分析冠心病合并左室室壁瘤形成患者仅行冠状动脉旁路移植术（CABG）但未同期行左心室成形术的疗效。 方法 2008年1月至2012年12月武汉亚洲心脏病医院收治冠心病合并室壁瘤患者共105例,术中探查发现室壁瘤边界欠清或活动欠佳或无明显矛盾运动而未处理室壁瘤患者共74例,其中男59例,女15例;年龄 （60.96±9.09） 岁。冠状动脉造影显示：单支血管病变5例,双支病变10例,3支病变45例,左主干＋3支病变14例。术中发现30例室壁瘤界限不清,29例心尖室壁变薄、室壁瘤不明显,15例室壁瘤未见明显的矛盾运动、心尖部质地较厚。所有患者均行冠状动脉旁路移植术。在体外循环下手术62例,非体外循环下手术12例。70例采用左乳内动脉吻合于左前降支,2例行左前降支内膜剥脱术。因二尖瓣中-重度反流行二尖瓣成形术3例,二尖瓣置换术2例;因合并主动脉瓣重度狭窄同期行主动脉瓣置换术1例。 结果 术后因恶性心律失常、缺血、缺氧性脑病死亡2例 （2.7%）;因低心排血量、围术期心肌梗死、恶性心律失常等行主动脉内球囊反搏 （IABP） 辅助6例。术后随访70例,随访时间24～60 （43±12） 个月。随访期间发现心室内血栓形成8例,其中5例服用华法林1年内血栓消失,无1例发生血栓脱落栓塞事件。超声心动图检查提示：室壁瘤消失18例 （25.7%）。出院时、术后6个月、1年射血分数较术前明显增高 （术后6个月与术前比较：44%±6% vs. 39%±5%）,左心室舒张期末内径 ［术后6个月与术前比较：（54.37±6.28） mm vs. （59.24±6.24）mm］、左心室收缩期末内径与术前比较明显缩小 （P＜0.01）。但随着时间延长,左心室舒张期末内径、左心室收缩期末内径较出院时逐渐增大。 结论 对于合并室壁瘤的冠心病患者,根据术中探查实际情况未行左心室成形术仅行冠状动脉旁路移植术,术后射血分数、左心室舒张期末内径、左心室收缩期末内径均较术前明显改善,但术后心室扩大呈进行性发展。     

异丙酚对体外循环中脑氧代谢的影响

目的：探讨异丙酚对体外循环（ＣＰＢ）各阶段脑氧及乳酸代谢的影响。方法：选择心内直视手术病人３１例，随机分为异现酚组（Ａ组）１６例，对照组（Ｂ组）１５例。分别于ＣＰＢ前、降温及３３℃和３０℃，低温期，复温至３０℃和３３℃以及ＣＰＢ后１５分钟七个时点动脉，颈内静脉血气及乳酸值（ＬＡ）并计算脑摄氧率（Ｏ２Ｅｘｔ）及动脉－颈内静脉乳酸差值。     

间断缺血心停搏在冠脉搭桥术中的应用

１９９２～１９９３年间为１８０例冠脉病变的病人施行冠脉搭桥术，全部病人均采用核甙抑制剂利多氟嗪预处理和低温（２８℃）间断缺血心停搏进行术中心肌保护。平均每例病人作冠状动脉端吻合３～４个，每个吻合口用９分钟，主动脉阻断累加时间约２５分钟，体外循环时间９０分钟，术后医院死亡率１．６％（３／１８０），无术后心梗发生。作者认为，冠脉搭桥术的术中心肌保护可采用核甙抑制剂和间断缺血心停搏方法，而不用心肌停搏液。     

左心转流在胸部降主动脉瘤手术中的应用

目的探讨左心转流在降主动脉瘤手术治疗中的应用。方法11例降主动脉癌患者,均行左心转流降主动脉人工血管置换术。结果全部患者的治疗效果均十分满意,1例术后胸腔出血并肺部感染,经再次开胸止血,联合应用抗生素和全身支持治疗后痊愈,其余患者均无并发症发生。结论左心转流下行胸部降主动脉瘤手术是积极安全有效的。     

The Effect of Left Ventricular Bypass on the Right Ventricular Function: Experimental Analysis of the Effects of Ischemic Injuries to the Right Ventricular Free Wall and Interventricular Septum

The right ventricular (RV) function during left heart bypass (LHB) was examined in open-chest anesthetized mongrel dogs (average weight, 11.8 kg). The LHB was carried out by a left ventricle (LV) to femoral artery bypass using a centrifugal pump for 90 min, and the bypass flow was kept maximum to obtain almost complete decompression of the LV. The RV function was evaluated by hemodynamic parameters and pressure-dimension (sonomicrometry) relationship at pre-LHB (control) and 30, 60, and 90 min after LHB (LHB-30, LHB-60, and LHB-90). The materials were divided into three groups after LHB-30: intact heart (group 1, n = 5), RV free wall ischemia (group 2, n = 5), and interventricular septum (IVS) ischemia group (group 3, n = 8). No significant changes in mean right atrial pressure (mRAP), RV end-diastolic pressure (RVEDP), RV maximum derivative pressure, or RV fractional shortening (RVFS) were found between pre-LHB and post-LHB in groups 1 and 2. On the contrary, group 3 showed significant increases in mRAP and RVEDP, and a decrease in RVFS at LHB-90 compared to both pre-LHB and LHB-30. The RV end-systolic dimension (percentage of pre-LHB) showed significant increases at LHB-90 compared to LHB-30 in groups 2 and 3. These results indicate that the LHB itself does not depress the RV function in the intact heart and in the RV free wall ischemic heart, while the impairment of the IVS during LHB appears to lead to RV dysfunction.     

Numerical Simulation of Nonpulsatile Left Ventricular Bypass

Abstract: A computer simulation was carried out to investigate the influence of nonpulsatile left ventricular assistance on hemodynamics. A simulation circuit was constructed to represent the circulatory system. A source of current was added to denote the nonpulsatile blood pump. The left and right ventricles were replaced by variable compliances. Left heart failure was simulated by decreasing the amount of compliance change of the left ventricle. We introduced a pulsatility indicator (PI) to clarify the pulsatility characteristics in the hemodynamics; this PI was defined as the ratio of the pulse pressure (PP) to the mean aortic pressure (AoP). When nonpulsatile bypass flow increased, the mean AoP, tension time index (TTI), and diastolic pressure time index (DPTI) increased, and cardiac output, PP, and PI decreased. When assisted flow increased with the constant total flow rate, the mean AoP and DPTI changed little; the PP, TTI, and PI decreased, and the endocardial viability rate increased. The PI would be helpful in evaluating the effect of pulsatility.