Rest ventricular function in left heart bypass

During partial left heart bypass (LHBP), the flow delivered by an assist device is easy to measure while residual left ventricular function (LVI) seems difficult to assess. In this study, we have attempted to define the separate right and left ventricular function during LHBP. In 6 anesthetized dogs, following thoracotomy and systemic heparinization, aorta and left atrium were cannulated and connected to the servo-controlled roller pump (modified St?ckert-System). Following saline infusion (30 ml/kg), LHBP was started and maintained at 50 ml/min/kg throughout 6 h. Standard hemodynamic parameters were continuously monitored. Cardiac output, blood gas analyses, hemoglobin and activated coagulation time were measured at regular intervals. LVI was calculated as the difference between cardiac output and assist-flow rate. Other derived variables were obtained using standard formulas. The Wilcoxon rank-test was used for the statistical analysis. The results, as median and 25th-75th percentile, are summarized in the graphics 1-6. Under the experimental conditions of this study, the flow performance and stroke work of the right ventricle remained unchanged, while the work-unloaded left ventricle maintained only a part of systemic perfusion. Neglecting the physiological shunt and its changes, which influences the difference between the left and right ventricular output, the simple formula to assess LVI during LHBP seems plausible.     

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.     

Heparinless cardiopulmonary bypass with argatroban in dogs.

OBJECTIVES: Systemic heparinization is usually required for cardiopulmonary bypass (CPB). However, problems such as heparin-induced thrombocytopenia, protamine shock, and antithrombin III deficiency exist related to CPB with heparinization. The aim of this study was to evaluate argatroban (ARG) as a substitute for heparin during CPB. METHODS: In the pilot study, blood samples were sequentially obtained from dogs with continuous infusion of ARG at a dose of 10 (n = 6), 20 (n = 6), or 30 (n = 6) microg/kg per min for 2 h without CPB. In the main study, dogs underwent CPB for 2 h with 10 (n = 6) or 30 (n = 6) microg/kg per min of ARG or with heparin with blood samples obtained sequentially. Thrombogenicity in each group was evaluated by observation of the blood-contacting surfaces of the CPB circuits with scanning electron microscopy (SEM). Evidence of thromboembolism in the dogs was also investigated in histological specimens of the kidney and spleen in addition to microscopic observation at autopsy. RESULTS: In the pilot study, the activated coagulation time (ACT) reached a maximum level dose-dependently after continuous infusion of ARG for 30 min. ACT returned to the baseline value within 60 min after the termination of continuous infusion. In the main study, CPB with 30 microg/kg per min of ARG achieved thrombin-antithrombin III complex (TAT) level similar to that achieved by CPB with heparin. Platelet count with 30 microg/kg per min of ARG tended to be higher than that with heparin or 10 microg/kg per min of ARG. The SEM appearance of blood-contacting surfaces of the CPB circuits after infusion with 30 microg/kg per min of ARG appeared to be similar to that after infusion with heparin. Depositions on the blood-contacting surfaces of the CPB circuits were also frequently observed with 10 microg/kg per min of ARG. CONCLUSIONS: Coagulability related to CPB was controlled by the appropriate ARG dosage without the use of heparin in dogs. ARG may be a substitute for heparin in CPB.     

High-dose fentanyl reduces intraoperative ventricular fibrillation in neonates with hypoplastic left heart syndrome

STUDY OBJECTIVE: To determine retrospectively the effect of high-dose opiate-oxygen (O2) anesthetic technique on intraoperative ventricular fibrillation in high-risk neonates. DESIGN: Retrospective chart review of different anesthetic techniques in a partially contemporaneous patient group (1981 to 1983). SETTING: Cardiac anesthesia service at a university pediatric hospital. PATIENTS: Forty neonates undergoing Norwood Stage I repair of hypoplastic left heart syndrome. INTERVENTIONS: High-dose fentanyl-O2 anesthesia in 30 neonates and low-dose morphine sulfate 50%-nitrous oxide (N2O) in 10 neonates. MEASUREMENTS AND MAIN RESULTS: Clinical condition assessed by preoperative and intraoperative arterial blood gases, requirements for sodium bicarbonate (NaHCO3), need for inotropic and pressor support, and vital signs. Outcome assessments by intraoperative ventricular fibrillation (frequency before and after bypass) and hospital mortality. Clinical condition and hospital mortality were no different. The frequency of intraoperative ventricular fibrillation was significantly different: 3% with high-dose fentanyl and 50% with morphine-N2O (p less than 0.005). CONCLUSIONS: High-dose opiate-O2 anesthesia in these patients markedly decreased intraoperative ventricular fibrillation. Other clinical reports and recent experimental work suggest that this finding is due to high-dose opiates rather than the avoidance of N2O.     

CardioWest total artificial heart in a moribund adolescent with left ventricular thrombi

Bridge to transplant is a well-known strategy to enable patients with congestive heart failure to live until transplant. A 15-year-old boy with Beckers' muscular dystrophy and cardiomyopathy was accepted for heart transplantation. He suffered a cardiac arrest and was placed on extracorporeal membrane oxygenator. A paracorporeal biventricular assist device and a total artificial heart were considered for bridge to transplant. A CardioWest total artificial heart was chosen because of the patient's size. Multiple left ventricular thrombi were identified at the time of the ventriculectomy. The patient did well with the total artificial heart was transplanted and discharged home. The unknown presence of significant left ventricular thrombi raises the question of outcome with a paracorporeal ventricular assist device.     

Heparinless extracorporeal bypass for treatment of hypothermia

In an attempt to assess the changes occurring to the coagulation profile during internal active core rewarming with partial cardiopulmonary bypass (CPB) without heparin anticoagulation, five pigs were anesthetized, and a model for severe to moderate hypothermia was created. Femoral-femoral bypass with Bio-Pump, heat exchanger, and a membrane oxygenator were used during the rewarming for 64.8 +/- 8.5 minutes. There were no statistically significant changes in platelet count, platelet index, activated clotting time (ACT), partial thromboplastin time (PTT), prothrombin time (PT), fibrinogen, fibrinogen index and fibrin split products (p greater than 0.05). There were no thromboembolic sequelae seen at autopsy. The components of the CPB circuit showed no signs of formation of aggregates or thrombi. The results of this study are attributed to the nonthrombogenic, atraumatic design of the Bio-Pump and the enhanced physiological fibrinolysis seen in the first hour of CPB. We concluded that heparinless CPB may serve as a safe alternative for active core rewarming for severe to moderate hypothermia.     

Coronary artery bypass grafting in patients with ventricular fibrillation

The role of coronary artery revascularization in the management of survivors of cardiac arrest remains controversial. Patients with sustained monomorphic ventricular tachycardia rarely respond to revascularization, but the response of patients with ventricular fibrillation as their basic arrhythmia has not been characterized. Coronary artery bypass grafting was performed in 8 patients with a history of cardiac arrest known to be caused by ventricular fibrillation without preceding sustained monomorphic ventricular tachycardia. All patients had critical double-vessel or triple-vessel coronary artery disease, and 7 of 8 had wall motion abnormalities from a prior myocardial infarction. After successful operation, 5 patients had no spontaneous arrhythmias and no inducible arrhythmias at a postoperative electrophysiological study. Three patients, however, had spontaneous, recurrent episodes of ventricular fibrillation unassociated with recurrent ischemia. Clinical factors were not useful predictors of response. The effect of coronary artery revascularization in patients with ventricular fibrillation is unpredictable, and full postoperative electrophysiological evaluation is necessary to judge the success of the procedure.     

Tei指数评价冠心病合并房颤患者左心室功能

目的探讨Tei指数评价冠心病（CHD）合并心房颤动（AF）患者左心室功能的临床应用价值。方法 60例CHD合并AF患者分为两组：快速AF组30例（心率≥120次/分）,慢速AF组30例（心率〈120次/分）;另选取30名健康人作为对照组。应用多普勒超声心动图检测左心室Tei指数及各传统指标,包括二尖瓣舒张早期血流峰值速度（E峰）、舒张晚期血流峰值速度（A峰）、E峰减速时间（DT）、瓣环平均收缩期血流速度（Sm）、平均舒张早期血流速度（Em）、平均舒张晚期血流速度（Am）、E/Em及左心室射血分数（LVEF）;并进行统计学分析。结果与对照组相比,CHD合并AF各组Tei指数明显升高（P〈0.05）。快速AF组与慢速AF组比较,Tei指数差异有统计学意义（P〈0.05）。Tei指数与E峰、E/Em正相关,与DT、Em、Sm、LVEF呈负相关。结论 Tei指数可用以评价CHD合并AF患者的左心室功能。