Simultaneous right ventricular contraction and left ventricular fibrillation during cardiopulmonary bypass.

Two cases of brief left ventricular fibrillation concurrent with a beating right ventricle during cardiopulmonary bypass are described. Although no left or right ventricular dysfunction was detected postoperatively, this regional electrical heterogenicity suggests inhomogeneous myocardial protection during at least a short period of time. The precise mechanisms concerned are not clear and limited clinical and animal experimental analogies can be found in the literature.     

The effect of ketanserin on blood pressure and platelets during cardiopulmonary bypass

Ketanserin, a serotonin antagonist, was used to control blood pressure during cardiopulmonary bypass in 12 patients having cardiac surgery. The drug was administered as a 10 mg bolus followed by a continuous infusion of either 40, 80, or 120 mg/hr to maintain mean arterial blood pressure below 70 mm Hg. There were 16 hypertensive episodes of which 15 (93.7%) were successfully controlled with ketanserin. Mean arterial pressure decreased significantly from an average of 72 +/- 3 to 52 +/- 9 mm Hg after 1 min. The effect that ketanserin had on platelets was also evaluated. Neither adverse nor salutary effects were seen in the platelet count, though a significant inhibition of serotonin-induced platelet aggregation was observed. Ketanserin proved effective for controlling hypertension during cardiopulmonary bypass but, despite inhibition of serotonin-induced platelet aggregation, it did not prevent thrombocytopenia.     

The effect of age on cerebral blood flow during hypothermic cardiopulmonary bypass

Cerebral blood flow was measured in 20 patients by xenon 133 clearance methodology during nonpulsatile hypothermic cardiopulmonary bypass to determine the effect of age on regional cerebral blood flow during these conditions. Measurements of cerebral blood flow at varying perfusion pressures were made in patients arbitrarily divided into two age groups at nearly identical nasopharyngeal temperature, hematocrit value, and carbon dioxide tension and with equal cardiopulmonary bypass flows of 1.6 L/min/m2. The range of mean arterial pressure was 30 to 110 mm Hg for group I (less than or equal to 50 years of age) and 20 to 90 mm Hg for group II (greater than or equal to 65 years of age). There was no significant difference (p = 0.32) between the mean arterial pressure in group I (54 +/- 28 mm Hg) and that in group II (43 +/- 21 mm Hg). The range of cerebral blood flow was 14.8 to 29.2 ml/100 gm/min for group I and 13.8 to 37.5 ml/100 gm/min for group II. There was no significant difference (p = 0.37) between the mean cerebral blood flow in group I (21.5 +/- 4.6 ml/100 gm/min) and group II (24.3 +/- 8.1 ml/100 gm/min). There was a poor correlation between mean arterial pressure and cerebral blood flow in both groups: group I, r = 0.16 (p = 0.67); group II, r = 0.5 (p = 0.12). In 12 patients, a second cerebral blood flow measurements was taken to determine the effect of mean arterial pressure on cerebral blood flow in the individual patient. Changes in mean arterial pressure did not correlate with changes in cerebral blood flow (p less than 0.90). We conclude that age does not alter cerebral blood flow and that cerebral blood flow autoregulation is preserved in elderly patients during nonpulsatile hypothermic cardiopulmonary bypass.     

地尔硫䓬对心肺转流下冠状动脉旁路移植术患者左心室功能的影响

目的探究小剂量地尔硫在心肺转流(CPB)下冠状动脉旁路移植术(CABG)术中应用是否产生抗动脉痉挛作用及左心室负性肌力作用。方法选择择期行CPB下CABG患者43例,男27例,女16例,年龄45~79岁,BMI 18~30 kg/m²,ASAⅡ或Ⅲ级,NYHAⅡ或Ⅲ级,术前左心室射血分数(LVEF)≥45%。随机分为两组:地尔硫组(D组)和对照组(C组),术中均采用全凭静脉麻醉。在置入经食管超声心动图(TEE)探头后,D组静脉输注地尔硫0.5μg·kg^-1·min^-1,C组给予生理盐水,均连续静脉输注至手术结束。在置入TEE探头即刻(T 0)、置入TEE探头后30 min(T₁)、CPB断流20 min(T₂)、50 min(T₃)采用TEE探头采集心脏超声图像,通过斑点追踪技术(STI)离线处理图像,分析并记录左心室功能STI指标:整体纵向应变力(GLS)、整体环向应变力(GCS)、整体纵向达峰时间标准差(GLTSD)、整体环向达峰时间标准差(GCTSD);同时记录传统心功能指标:CI及LVEF;记录左侧乳内动脉桥(LIMA)血流及术后房颤(POAF)发生率、呼吸支持时间、ICU停留时间及总住院时间等术后恢复指标。结果两组不同时点左心室收缩功能及运动同步化指标GLS、GCS、GLTSD、GCTSD差异无统计学意义;两组CI、LVEF差异无统计学意义。D组LIMA血流量高于C组(P<0.05);D组术后6 h cTnI浓度明显低于C组(P<0.05),两组POAF发生率、呼吸支持时间、ICU停留时间及总住院时间差异无统计学意义。结论小剂量地尔硫在CABG术中应用可增加动脉桥血管血流量,同时不产生左心室负性肌力作用。     

Retransfusion of pericardial blood does not trigger systemic coagulation during cardiopulmonary bypass

Objective: During cardiopulmonary bypass (CPB), systemic coagulation is believed to become activated by blood contact with the extracorporeal circuit and by retransfusion of pericardial blood. To which extent retransfusion activates systemic coagulation, however, is unknown. We investigated to which extent retransfusion of pericardial blood triggers systemic coagulation during CPB. Methods: Thirteen patients undergoing elective coronary artery bypass grafting surgery were included. Pericardial blood was retransfused into nine patients and retained in four patients. Systemic samples were collected before, during and after CPB, and pericardial samples before retransfusion. Levels of prothrombin fragment F₁₊₂ (ELISA), microparticles (flow cytometry) and non-cell bound (soluble) tissue factor (sTF; ELISA) were determined. Results: Compared to systemic blood, pericardial blood contained elevated levels of F₁₊₂, microparticles and sTF. During CPB, systemic levels of F₁₊₂ increased from 0.28 (0.25–0.37; median, interquartile range) to 1.10 (0.49–1.55) nmol/l (p = 0.001). This observed increase was similar to the estimated (calculated) increase (p = 0.424), and differed significantly between retransfused and non-retransfused patients (1.12 nmol/l vs 0.02 nmol/l, p = 0.001). Also, the observed systemic increases of platelet- and erythrocyte-derived microparticles and sTF were in line with predicted increases (p = 0.868, p = 0.778 and p = 0.205, respectively). Before neutralization of heparin, microparticles and other coagulant phospholipids decreased from 464 μg/ml (287–701) to 163 μg/ml (121–389) in retransfused patients (p = 0.001), indicating rapid clearance after retransfusion. Conclusion: Retransfusion of pericardial blood does not activate systemic coagulation under heparinization. The observed increases in systemic levels of F₁₊₂, microparticles and sTF during CPB are explained by dilution of retransfused pericardial blood.     

乌司他丁对心内直视手术围体外循环期血液纤溶系统和血小板功能的作用

目的 评价乌司他丁(UTI)对心内直视手术围体外循环(CPB)期血液纤溶系统和血小板功能的作用。方法 选择20例CPB病人,随机分为观察组(U组)和对照组(C组)。U组于切皮后至CPB开始前缓慢静注UTI半量(6000 U/kg),另半量加入预充液中;C组用生理盐水替代UTI,用药方法同U组。分别于CPB前(T1)、CPB开始后30 min(T2)、停CPB即刻(T3)、停CPB 2 h(T4)和24 h(T5)抽取桡动脉血,检测血浆栓溶二聚体(D-Dimer)、α-颗粒膜蛋白-140(GMP-140)、血栓素B2(TXB2)、6-酮-前列腺素F1α(6-Keto-PGF1α)的浓度,并记录术后胸腔引流量。结果 两组病人一般资料差异无统计学意义;与CPB前(T1)相比,C组血浆D-Dimer、GMP-140、TXB2、TXB2/6-Keto-PGF1α于T2-T4各时点均升高(P<0.05-0.01);U组以上各指标的升高幅度较C组降低(P<0.05-0.01);术后胸腔引流量较C组明显减少(P<0.05)。结论 心内直视手术围CPB期血液纤溶系统活性亢进,血小板功能有异常改变,易致术后出血;应用UTI(12 000 U/kg)在一定程度上能维持纤溶活性稳定、保护血小板功能,从而减少了术后出血。     

Effects of calcium on left ventricular function early after cardiopulmonary bypass

Evaluation of the effects of intravenous CaC1₂on systolic and diastolic function early after separation from cardiopulmonary bypass (CPB) Prospective study University hospital Twenty patients scheduled for elective coronary artery surgery Left ventricular (LV) pressures were measured with fluid-filled catheters. Data were digitally recorded during pressure elevation induced by tilt-up of the legs. Transgastric short-axis echocardiographic views of the LV were simultaneously recorded on videotape. Measurements were obtained before the start of CPB, 10 minutes after termination of CPB, after intravenous administration of CaC1₂, 5 mg/kg, and 10 minutes later.

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Systolic function was evaluated with the slope (Ees, mmHg/mL) of the systolic pressure-volume relation. Diastolic function was evaluated with the chamber stiffness constant (Kc, mmHg/mL) of the diastolic pressure-volume relation. CaC1₂increased Ees from 2.62 ± 0.46 to 5.58 ± 0.61 (mean ± SD), but induced diastolic dysfunction with an increase in Kc from 0.011 ± 0.006 to 0.019 ± 0.007. These changes were transient and had disappeared within 10 minutes after administration of CaC1₂. CaC1₂early after CPB transiently improved systolic function at the expense of an increase in ventricular stiffness, suggesting temporary diastolic dysfunction.     

小剂量抑肽酶对体外循环中血小板的保护

选择４５例心脏瓣膜置换术患者，其中２３例应用小剂量抑肽酶作为用药组，观察体外循环期间小剂量抑肽酶降低术后失血量的作用。结果显示：用药组术后失血量比对照组减少了５０．２％，输血量减少了６７．０％。抑肽酶可减缓血小板计数的骤然下降趋势，但并不阻止其下降。血小板聚集功能及粘附功能的下降在用药组明显较轻，而胞浆游离［Ｃａ２＋」ｉ、膜磷脂酶Ａ２和环氧化酶活性的上升明显被抑制。结论：小剂量抑肽酶可明显减少术后失血量及输血量，具有与大剂量抑肽酶同样的临床效果。对于血小板胞浆游离［Ｃａ２＋］ｉ及膜磷脂酶Ａ２、环氧化酶活性升高的抑制作用是抑肽酶作用机制的一个重要方面。     

Two-dimensional echocardiography in dogs. Variation of left ventricular mass, geometry, volume, and ejection fraction on cardiopulmonary bypass

Quantitative two-dimensional echocardiography was evaluated in 39 open-chest dogs placed on cardiopulmonary bypass. The correlation coefficient of left ventricular end-diastolic volume against postmortem pressure-volume curves was r = 0.89 to 0.93 (347 measurements in 15 dogs, 0 to 24 mm Hg). Ejection fraction was validated against roller pump flow and echo left ventricular end-diastolic volume (r = 0.83, n = 13). Left ventricular mass in vivo was compared with postmortem left ventricular mass (r = 0.81 in 21 early studies, r = 0.91 in 10 later studies with updated equipment) and was found to increase with ischemic injury as well as cardiopulmonary bypass with hemodilution. Left ventricular mass increased (p less than 0.001) from 119 +/- 5 (standard error of the mean) to 138 +/- 6 gm (n = 23) after 2 1/2 hours on cardiopulmonary bypass and moderate hemodilution. With the addition of ischemic arrest, left ventricular mass increased from 119 +/- 7 to 148 +/- 11 gm (p less than 0.01, n = 8), and myocardial water content increased by 2.0% +/- 0.4%, which accounted for at least 65% of the observed mass change. Mean left ventricular wall thickness increased from 13.8 to 15.5 mm (p = 0.02) after ischemia. Ventricular shape became more spherical with increasing left ventricular end-diastolic pressure. We conclude that two-dimensional echocardiography can be reliably used for accurate, serial measurements in physiological studies. The demonstrated variability in left ventricular mass is important, yet frequently ignored. Recognizing left ventricular mass changes may facilitate the detection of myocardial injury reflected as edema.     

The effect of high-frequency ventilation of the lungs on postbypass oxygenation: A comparison with other ventilation methods applied during cardiopulmonary bypass

OBJECTIVE: To compare the effect of high-frequency ventilation versus other ventilation methods applied during cardiopulmonary bypass on postbypass oxygenation. DESIGN: Prospective, randomized study. SETTING: University hospital. PARTICIPANTS: Seventy-five patients undergoing coronary artery bypass graft surgery. INTERVENTIONS: Patients were allocated to 5 equal groups of different ventilation methods during bypass. Groups 1 and 2 received high-frequency, low-volume ventilation with 100% and 21% oxygen, respectively. Groups 3 and 4 received 5 cm H(2)O of continuous positive airway pressure (CPAP) with either 100% or 21% oxygen. Patients from group 5 were disconnected from the ventilator during the bypass period. MEASUREMENTS AND MAIN RESULTS: Spirometry data, blood gas analysis, oxygen saturation as measured by pulse oximetry, and end-tidal carbon dioxide were recorded 5 minutes before chest opening, 5 minutes before bypass, 5 minutes after bypass, 5 minutes after chest closure and 6, 12, 18, and 24 hours after surgery. There were no differences in compliance and mean airway pressures. Alveolar-to-arterial oxygen gradients increased, and PaO(2) decreased significantly (p < 0.05) in all groups 5 minutes after bypass and this trend continued in the postoperative period. Patients from group 3 had higher PaO(2) and lower alveolar-to-arterial oxygen gradients, 5 minutes after weaning from bypass (p < 0.05). Extubation times were similar in all groups. CONCLUSIONS: The alveolar-arterial oxygen gradient was lower, and the PaO(2) was higher 5 minutes after bypass in patients receiving CPAP (100% O(2)) as compared with those ventilated with high-frequency ventilation.     

The effect of temperature on cerebral metabolism and blood flow in adults during cardiopulmonary bypass.

The effect of temperature on cerebral blood flow and metabolism was studied in 41 adult patients scheduled for operations requiring cardiopulmonary bypass. Plasma levels of midazolam and fentanyl were kept constant by a pharmacokinetic model-driven infusion system. Cerebral blood flow was measured by xenon 133 clearance (initial slope index) methods. Cerebral blood flow determinations were made at 27 degrees C (hypothermia) and 37 degrees C (normothermia) at constant cardiopulmonary bypass pump flows of 2 L/min/m2. Blood gas management was conducted to maintain arterial carbon dioxide tension (not corrected for temperature) 35 to 40 mm Hg and arterial oxygen tension of 150 to 250 mm Hg. Blood gas samples were taken from the radial artery and the jugular bulb. With decreased temperature there was a significant (p less than 0.0001) decrease in the arterial venous-oxygen content difference, suggesting brain flow in excess of metabolic need. For each patient, the cerebral metabolic rate of oxygen consumption at 37 degrees C and 27 degrees C was calculated from the two measured points at normothermia and hypothermia with the use of a linear relationship between the logarithm of cerebral metabolic rate of oxygen consumption and temperature. The temperature coefficient was then computed as the ratio of cerebral metabolic rate of oxygen consumption at 37 degrees C to that at 27 degrees C. The median temperature coefficient for man on nonpulsatile cardiopulmonary bypass is 2.8. Thus reducing the temperature from 37 degrees to 27 degrees C reduces cerebral metabolic rate of oxygen consumption by 64%.     

氨茶碱在体外循环中对肺的保护作用

目的探讨氨茶碱对体外循环(CPB)所致肺损伤的保护作用.方法选择心瓣膜置换术患者20例,采用随机化分组表分为氨茶碱组和对照组,每组10例.氨茶碱组于麻醉诱导后缓慢(5分钟)静脉注射氨茶碱(5 mg/kg),其后按0.5mg/kg·h经微量泵持续静脉注射;对照组用等容量平衡盐溶液静脉注射.两组均于CPB前、CPB结束后1、8和24小时测定肿瘤坏死因子-α(TNF-α)、白细胞介素-8(IL-8)、白细胞介素-10(IL-10)的血浆水平,同时测量两组患者围术期血流动力学、呼吸指数(RI)、右心房血/左心房血中性粒细胞比值和血浆丙二醛(MDA)含量等.结果CPB结束后1小时和8小时,对照组RI较CPB前和氨茶碱组明显增高(P<0.05),氨茶碱明显抑制了中性粒细胞在肺内的聚集,抑制TNF-α和IL-8的释放,减少MDA产生,促进IL-10的产生.结论氨茶碱能够减轻炎性反应和CPB导致的肺损伤.     

The effect of diuretics on renal hemodynamics during cardiopulmonary bypass

The effect of cardiopulmonary bypass (CPB) on renal hemodynamics was studied in 15 dogs using ¹³³xenon washout. Ten control dogs had no diuretics administered and five diuretic dogs were given furosemide immediately before and during CPB. A catheter was inserted into the right renal artery under fluoroscopic guidance via the left femoral artery and a bolus of ¹³³xenon injected. Washout curves were obtained with a collimater placed over the kidney before CPB and after 15 and 90 min of CPB. Total CPB was undertaken at normothermia using venous gravity drainage, an arterial roller pump, a heat exchanger and a Kolobow membrane oxygenator. Washout curves were analyzed and four components of renal blood flow (RBF) developed: I, cortex; II, juxtamedulla; III, inner medulla; and IV, hilar fat. Percentage of total radioactivity and regional blood flow was derived for each component and total RBF calculated.Total RBF in the control group decreased progressively during CPB (457 → 269 → 158 ml/100 g/min after 90-min CPB). This decrease in RBF was associated with a marked shunt of flow from cortical to juxtamedullary region. Percentage of flow to the cortex decreased as well (68% → 33% → 23% after 90 min) while activity to the juxtamedulla increased (24% → 47% → 50% after 90 min).RBF in the diuretic treated group decreased during CPB but significantly less than in the control group (436 → 397 → 273 ml/100 g/min after 90-min CPB). The intrarenal shunt seen in the control group during CPB was significantly reduced in the diuretic treated group. While percent flow to the cortex was reduced as bypass progressed (67% → 56% → 47% after 90 min), cortical activity remained greater than juxtamedullary (29% → 36% → 38% after 90 min) throughout the 2 hr of bypass. It was apparent from this study that cortical ischemia associated with CPB can be substantially reduced by diuretic therapy during CPB.