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1.
Occlusion of the left coronary artery in rats provoked ventricular tachycardia (VT) and ventricular fibrillation (VF) within the first 30 min of ischemia leading to death in 20% animals. Methacin (i.v., 100 micrograms/kg) significantly prolonged VT and VF without effects on the survival. Acetylcholine (i.v., 10 micrograms/kg/min) had no influence on VT frequency and severity but prevented VF. Rats from this group survived. The same effect was observed for neostigmine (i.v., 25 micrograms/kg). Nicotine (i.v., 2.5 micrograms/kg/min) prolonged VT episode duration but did not change frequency and severity of VF and survival. Ganglioblockers hexametony and azametony (i.v., both in a dose 500 micrograms/kg) significantly attenuated VT, prevented VF and death of the animals. Thus, cholinotropic drugs may have both antiarrhythmic and proarrhythmogenic effects in early arrhythmias induced by ischemia.  相似文献   

2.
Background: Improved microcirculatory reperfusion in patients with ventricular fibrillation (VF) enhances the electrical activity of the fibrillation process and increases the likelihood of successful defibrillation.

Methods: Changes in amplitude spectrum area (AMSA) and mean fibrillation (MF) in patients with sustained VF were analysed after administration of rt-PA variant tenecteplase in out-of-hospital cardiac arrest (OHCA) during cardiopulmonary resuscitation (CPR).

Results: A total of 69 ECG sequences from nine patients were evaluated. Patients who received tenecteplase showed significantly longer duration of VF (p?=?0.016). While AMSA declined significantly during CPR (p?=?0.001), MF did not differ between groups. There were two survivors in the treatment group and one in the control group.

Conclusion: When tenecteplase was administered during CPR, VF lasted significantly longer than in controls. Changes in MF and AMSA did not indicate improved myocardial perfusion in patients who received tenecteplase during CPR.  相似文献   

3.
The likelihood of successful defibrillation in patients with sustained ventricular fibrillation (VF) is increased after administering thrombolytics during cardiopulmonary resuscitation (CPR). While dissolution of coronary artery thrombosis resolves the underlying cause of myocardial infarction in the majority of patients, improved microcirculatory reperfusion and alteration of the electrical activity of the fibrillation process may increase the likelihood of restoring spontaneous circulation in cardiac arrest patients. Electrocardiography is a sensitive means of displaying current myocardial perfusion in VF using changes in the frequency and amplitude of fibrillation. Our hypothesis postulates that thrombolytic therapy during CPR increases fibrillation frequency, fibrillation amplitude and amplitude spectrum area, thus improving ventricular fibrillation status and the chance of successful defibrillation.  相似文献   

4.
Sudden cardiac death prematurely claims the lives of some 7 million each year worldwide. It occurs primarily in patients with an underlying structural cardiac abnormality, and regardless of the type of the underlying pathology (heart failure, dilated and hypertrophic cardiomyopathies, myocardial infarction and aging), death is almost always caused by ventricular tachycardia (VT) which rapidly degenerates to ventricular fibrillation (VF). Implantable cardioverter defibrillator is an effective but expensive therapy for preventing SCD, and finding a reasonably specific, sensitive and cost-effective risk stratification tool for patients at high risk of sudden cardiac death will have great clinical utility in preventing premature sudden cardiac death. Increased myocardial fibrosis has been shown to develop in a wide range of cardiac diseases all manifesting increased risk of VT and VF. Clinical and experimental studies attribute a major role for fibrosis in the initiation of VT, VF and sudden cardiac death. Transforming growth factor-beta1 (TGF-beta1) has been shown to promote myocardial tissue fibrosis and perhaps more importantly in cardiac conditions associated with increased myocardial fibrosis are shown to be positively correlated with increased serum levels of TGF-beta1. In the present hypothesis we suggest that monitoring the serum levels of TGF-beta1 may be a cost-effective risk stratifier to identify patients at high risk of sudden cardiac death caused by VT and VF.  相似文献   

5.
目的:过速型室性心律失常[持续性室性心动过速或心室纤颤(VT/VF)]是心脏猝死的主要诱因,测试VT/VF发生前心率变异性信号是否有明显改变可作为VT和VF发生的提前预报信号。方法:以78名患者体内心脏复律除颤器记录的VT/VF事件发生前心率变异性信号(VT/VF序列)和来自同一患者的正常窦性节律(CON序列)组成的135个样本对作为实验序列。通过预处理消除实验序列的伪差、异位心搏等干扰,采用两种基于熵的非线性复杂度测度——样本熵和逐点多尺度熵(PPMSE),分析VT和VF发生前十几分钟的VT/VF序列,以及心率增加和减小的VT/VF序列复杂性,并采用PPMSE方法讨论了接近VT/VF发生时VT/VF序列复杂性变化。结果:与正常对照组CON序列相比,在一定匹配容差内,VT/VF发生前心率变异性信号的样本熵明显减小(r<0.25×SD, P<0.000 5),心率增加的VT/VF序列减小更显著(r<0.3×SD, P<0.000 1);VT/VF序列的PPMSE在越接近VT/VF发生时刻减小越显著,提取的CI指数存在显著差异(如1~30尺度,N=986、500、250时,P=1.5×10-2、P=4.3×10-3、P=1.3×10-5),心率增加的VT/VF序列区分性能更好。结论:过速型心律失常的自然发作并不是突发现象,在其发作前或许存在某种生理预兆,两种熵测度可能是短时预报恶性室性心律失常事件的有效非线性参数。  相似文献   

6.
Identification and classification of ventricular arrhythmias such as rhythmic ventricular tachycardia (VT) and disorganized ventricular fibrillation (VF) are vital tasks in guiding implantable devices to deliver appropriate therapy in preventing sudden cardiac deaths. Recent studies have shown VF can exhibit strong regional organizations, which makes the overlap zone between the fast paced rhythmic VT and VF even more ambiguous. Considering that implantable cardioverter-defibrillator (ICD) are primarily rate dependent detectors of arrhythmias and that there may be patients who suffer from arrhythmias that fall in the overlap zone, it is essential to identify the degree of affinity of the arrhythmia toward VT or organized/disorganized VF. The method proposed in this work better categorizes the overlap zone using Wavelet analysis of surface ECGs. Sixty-three surface ECG signal segments from the MIT-BIH database were used to classify between VT, organized VF (OVF), and disorganized VF (DVF). A two-level binary classifier was used to first extract VT with an overall accuracy of 93.7 % and then the separation between OVF and DVF with an accuracy of 80.0 %. The proposed approach could assist clinicians to provide optimal therapeutic solutions for patients in the overlap zone of VT and VF.  相似文献   

7.
BACKGROUND: Despite extensive training of citizens of Seattle in cardiopulmonary resuscitation (CPR), bystanders do not perform CPR in almost half of witnessed cardiac arrests. Instructions in chest compression plus mouth-to-mouth ventilation given by dispatchers over the telephone can require 2.4 minutes. In experimental studies, chest compression alone is associated with survival rates similar to those with chest compression plus mouth-to-mouth ventilation. We conducted a randomized study to compare CPR by chest compression alone with CPR by chest compression plus mouth-to-mouth ventilation. METHODS: The setting of the trial was an urban, fire-department-based, emergency-medical-care system with central dispatching. In a randomized manner, telephone dispatchers gave bystanders at the scene of apparent cardiac arrest instructions in either chest compression alone or chest compression plus mouth-to-mouth ventilation. The primary end point was survival to hospital discharge. RESULTS: Data were analyzed for 241 patients randomly assigned to receive chest compression alone and 279 assigned to chest compression plus mouth-to-mouth ventilation. Complete instructions were delivered in 62 percent of episodes for the group receiving chest compression plus mouth-to-mouth ventilation and 81 percent of episodes for the group receiving chest compression alone (P=0.005). Instructions for compression required 1.4 minutes less to complete than instructions for compression plus mouth-to-mouth ventilation. Survival to hospital discharge was better among patients assigned to chest compression alone than among those assigned to chest compression plus mouth-to-mouth ventilation (14.6 percent vs. 10.4 percent), but the difference was not statistically significant (P=0.18). CONCLUSIONS: The outcome after CPR with chest compression alone is similar to that after chest compression with mouth-to-mouth ventilation, and chest compression alone may be the preferred approach for bystanders inexperienced in CPR.  相似文献   

8.
To investigate non-invasively induced Wedensky modulation, 2 ms pulses of 5, 20 and 40 mA were delivered between precordial and subscapular patches synchronously with the QRS complex. Wavelet vector magnitude was obtained for averaged modulated and non-modulated complexes. The surface area of a 3D-envelope of their difference (WSR) was compared in 59 patients with an uncomplicated follow-up after myocardial infarction (MI) (42 men, 64.3±9.1 years), in 30 patients with ischaemic heart disease and a history of ventricular tachycardia/fibrillation (VT/VF) (29 men, 63.1±9.8 years), and in 53 healthy subjects (control) (22 men, 56.6±10.1 years). Reproducibility of the assessment was tested by computing relative errors in a sub-population of 30 VT/VF patients and 47 controls. Wedensky modulation parameters differed significantly between control, MI and VT/VF subjects. In 10 ms post-modulation windows, the following WSR values were obtained: controls: 1184±496 (5 mA), 1553±838 (20 mA) and 2092±1488 (40 mA); VT/VF: 861±412 (5 mA), 1134±636 (20 mA) and 1320±1036 (40 mA); MI: 1305±885 (5 mA) and 1779±1169 (20 mA). With all modulating energies used, the VT/VF patients differed significantly from both the controls and MI patients; control patients against VT/VF patients: p<0.004 (5 mA), p<0.01 (20 mA) and p<0.001 (40 mA); VT/VF patients against MI patients: p<0.02 (5 mA), p<0.01 (20 mA); control patients against MI patients: all p=NS. The reproducibility assessment showed an acceptable stability of Wedensky modulation parameters. This study demonstrated that wavelet decomposition detects non-invasive Wedensky modulation within the QRS complex, and VT/VF patients are less sensitive to Wedensky modulation than control and MI patients.  相似文献   

9.
Overdrive pacing has been applied in 26 patients to prevent frequent recurrent ventricular fibrillation (VF) and ventricular tachycardia (VT) occurring in the setting of ventricular extrasystole of 2-5 degrees graded by Lown. These patients had 3-47 recurrent attacks of VF and VT (11.4 +/- 2.4) which were not prevented with antiarrhythmic agents. Overdrive pacing was continued for 2-236 hours (21.3 +/- 3.7) and appeared to be effective in 23 (88.4%) of the 26 patients including those with prolonged QT intervals. Atrial pacing was more effective than ventricular overdriving and required stimulation at a slower rate. Antiarrhythmic therapy and overdrive pacing in combination were more effective than both used independently. Suppression of ventricular extrasystole and prevention of life-threatening arrhythmias were achieved by increasing the heart rate by 23.2 +/- 4.5 beats/min.  相似文献   

10.
A new organization has been formed in which ambulance personnel have been trained to recognize ventricular tachycardia and ventricular fibrillation (VF) and to defibrillate. Cardiac arrest (CA) occurred in 307 patients and 140 were defibrillated. Twenty-eight patients were resuscitated and admitted for further hospital care. A previous history of ischaemic heart disease was found in 24 patients. Twenty-two of the patients admitted were found to have VF, two asystole and four other rhythms. All 11 survivors regained circulation at the site of the CA. At the time of admission all but one of the patients were unconscious and one long-time survivor remained unconscious until the 5th day following admission. Seventeen patients died while still in hospital. In 16 cases a diagnosis of acute myocardial infarction was established, a further six had VF without evidence of acute myocardial infarction and six had other diagnoses. Ten out of the 11 survivors were still alive six months after discharge. Only one case of recurrent VF was seen during a median follow-up period of 16 months. Prolonged coma, especially in combination with convulsions, was associated with a poor prognosis, while early return of circulation was significantly more common among survivors. Ongoing medication with beta-blockers, a high QRS rate on admission and VF without proof of any acute myocardial infarction were also found to be more common in survivors.  相似文献   

11.
Ventricular fibrillation (VF) is one of the most serious malignant arrhythmias usually resulting from immediate degeneration of ventricular tachycardia (VT). In order to analyse the nonlinear dynamics of the cardiac micro-mechanism under VT and VF rhythm, at the cellular level, myocardial cell action potentials are investigated under different rhythm, normal sinus rhythm, VT and VF. On the basis of nonlinear chaotic theory and symbolic dynamics, we put forward new definitions, complexity rate, etc, and obtained some useful properties for cellular electrophysiological analysis. The results of the experiments and computation show that the myocardial cellular signals under VT and VF rhythm are different kinds of chaotic signals in that the cardiac chaos attractor under VF is higher than that under VT. The analytical complexity theory has been promising in the clinical application.  相似文献   

12.
Ventricular fibrillation (VF) is one of the most serious malignant arrhythmias usually resulting from immediate degeneration of ventricular tachycardia (VT). In order to analyse the nonlinear dynamics of the cardiac micro-mechanism under VT and VT rhythm, at the cellular level, myocardial cell action potentials are investigated under different rhythm, normal sinus rhythm, VT and VT. On the basis of nonlinear chaotic theory and symbolic dynamics, we put forward new definitions, complexity rate, etc, and obtained some useful properties for cellular electrophysiological analysis. The results of the experiments and computation show that the myocardial cellular signals under VT and VF rhythm are different kinds of chaotic signals in that the cardiac chaos attractor under VF is higher than that under VT. The analytical complexity theory has been promising in the clinical application.  相似文献   

13.
INTRODUCTION: Ventricular tachycardia (VT) is considered to be the most common precursor of ventricular fibrillation (VF) and sudden cardiac death. However, the mechanisms underlying the transition from VT to VF remain unclear despite more than a century of study. Here, we investigated whether perfusion of the heart with blockers of mitochondrial Ca(2+) uniporter changed the macrodynamics of the heart between VT and VF. METHODS: The experiments were performed using Langendorff perfused isolated rat hearts in which left ventricular pressure (LVP) and left ventricular cardiomyogram (LVCMG) were measured. Sustained VT or VF was induced by burst pacing of the left ventricular muscles. RESULTS: During pacing-induced sustained VF, perfusion of the heart with ruthenium red (RR) or Ru 360, blockers of mitochondrial Ca(2+) uniporter, resulted in the reversible conversion of VF to VT. In contrast, during pacing-induced sustained VT, perfusion of the heart with spermine, an activator of mitochondrial Ca(2+) uptake, resulted in the reversible conversion of VT to VF, and the effect was antagonized by cotreatment with RR. In addition, RR-induced conversion of VF to VT was antagonized by cotreatment with S(-)-Bay K8644 (Bay K), an activator of L-type Ca(2+) channels, suggesting that the inactivation of L-type Ca(2+) channels was responsible for the RR-induced effect on the macrodynamics of hearts. In fact, perfusion with verapamil, an antagonist of L-type Ca(2+) channels, during pacing-induced sustained VF, resulted in the conversion of VF to VT. CONCLUSION: This study demonstrated that perfusion of isolated rat hearts with blockers of Ca(2+) uptake by mitochondria resulted in the reversible conversion of pacing-induced sustained VF to VT, suggesting that changes in mitochondrial Ca(2+) uptake were possibly involved in the transition between VT and VF.  相似文献   

14.
心肌肽素抗心律失常作用及对钙和钾离子通道的影响   总被引:11,自引:2,他引:11       下载免费PDF全文
目的:观察心肌肽素对室速、室颤发生率及心室肌细胞钙、钾电流的影响。方法:建立整体动物心肌缺血-再灌流损伤模型。以膜片钳技术记录单个心室肌细胞内向钙电流及电流-电压曲线、内向整流钾电流及延迟整流钾电流。结果:心肌肽素可降低低室速、室颤发生率,在一定浓度下对心肌细胞内向钙向电流有明显的抑制作用,且该作用具有一定的电压依赖性,而对内向整流钾电流及延迟整流钾电流均无作用。结论:心肌肽素能降低缺血-再灌流损  相似文献   

15.
BACKGROUND: We previously observed that short-term survival after out-of-hospital cardiac arrest was greater with active compression-decompression cardiopulmonary resuscitation (CPR) than with standard CPR. In the current study, we assessed the effects of the active compression-decompression method on one-year survival. METHODS: Patients who had cardiac arrest in the Paris metropolitan area or in Thionville, France, more than 80 percent of whom had asystole, were assigned to receive either standard CPR (377 patients) or active compression-decompression CPR (373 patients) according to whether their arrest occurred on an even or odd day of the month, respectively. The primary end point was survival at one year. The rate of survival to hospital discharge without neurologic impairment and the neurologic outcome were secondary end points. RESULTS: Both the rate of hospital discharge without neurologic impairment (6 percent vs. 2 percent, P=0.01) and the one-year survival rate (5 percent vs. 2 percent, P=0.03) were significantly higher among patients who received active compression-decompression CPR than among those who received standard CPR. All patients who survived to one year had cardiac arrests that were witnessed. Nine of 17 one-year survivors in the active compression-decompression group and 2 of 7 in the standard group, respectively, initially had asystole or pulseless electrical activity. In 12 of the 17 survivors who had received active compression-decompression CPR, neurologic status returned to base line, as compared with 3 of 7 survivors who had received standard CPR (P=0.34). CONCLUSIONS: Active compression-decompression CPR performed during advanced life support significantly improved long-term survival rates among patients who had cardiac arrest outside the hospital.  相似文献   

16.
BACKGROUND--Early thrombolytic therapy for patients having a myocardial infarct size and improves survival. AIM--A study was undertaken to examine the components of pre-hospital delay in patients with retrospectively proven myocardial infarction. METHOD--Data were gathered from 300 patients with a documented myocardial infarction admitted to three hospitals in Rotterdam, the Netherlands. Interviews were carried out with patients, questionnaires were given to their spouses or significant others, medical information was provided by cardiologists, and logbook information was gathered from the ambulance service. RESULTS--Half of all patients (51%) called for medical help within 30 minutes of symptom onset. General practitioners arrived within 11 minutes in half of the 257 cases to which they were called. However, in half of the 257 cases, decision making by the general practitioner before the patient was sent to a hospital took more than 82 minutes. The ambulance arrived within 15 minutes in 90% of all 242 cases, while the time required for stabilization of the patient by the ambulance staff and transport to the hospital took a median of 15 minutes. CONCLUSION--Compared with earlier studies, patients with a myocardial infarction called for help sooner. However, it may take a considerable time before the general practitioner refers the patient to hospital. Further research is needed to design measures which will improve the diagnostic power of the general practitioner in order to further reduce pre-hospital delay.  相似文献   

17.
心脏性猝死严重威胁着全人类健康,而心室颤动(室颤)是导致心脏性猝死最主要的心律失常之一,尽管心肺复苏技术在不断地提高与完善,心脏骤停的抢救成功率仍很低,初期复苏成功后患者的死亡率仍然很高,改进和完善心肺复苏的疗效仍面临严峻挑战。本文就室颤救治及心肺复苏技术进展作一介绍。  相似文献   

18.
The purpose of this study was to evaluate the outcomes for out-of-hospital cardiac arrest (OHCA) and cardiopulmonary resuscitation (CPR) in the city of Okayama, Japan, during a 1-year period after the reorganization of defibrillation by Emergency Life-Saving Technicians (ELSTs) with standing orders of CPR. The data were collected prospectively according to an Utstein style between June 1, 2003 and May 31, 2004; OHCA was confirmed in 363 patients. Cardiac arrest of presumed cardiac etiology (179) was witnessed by a bystander in 62 (34.6%) cases. Of this group, ventricular fibrillation (VF) was documented in 20 cases (32.3%), and 1 patient (5%) was discharged alive without severe neurological disability. This outcome is average in Japan, but it is quite low level compared with Western countries because there is less VF in Japan. The Utstein style revealed that we must try to detect VF before the rhythm changes and to provide defibrillation as soon as possible in order to improve outcomes. Further research will be required to accurately evaluate OHCA in Okayama city.  相似文献   

19.
INTRODUCTION: The relationship between vulnerability to reperfusion-induced ventricular tachyarrhythmias, such as ventricular tachycardia (VT) and fibrillation (VF), and the endogenous activity of nitric oxide synthase (NOS) has not been well documented. The objective of the present study was to clarify whether the vulnerability to reperfusion-induced VT/VF changes with preishemic, sustained inhibition of NOS. METHODS: The experiments were performed using Langendorff-perfused isolated rat hearts, in which left ventricular pressure (LVP) and left ventricular cardiomyograms (LVCMGs) were measured. RESULTS: A pre-ischemic, sustained inhibition of NOS resulted in an increased vulnerability to reperfusion-induced VT/VF, and the increase was markedly attenuated by co-treatment with L-arginine or by post-ischemic treatment with 2,4-diamino-6-hydroxypyrimidine (DAHP), an inhibitor of tetrahydrobiopterin (BH(4)) synthesis. We then tried to elucidate whether nitric oxide (NO) and superoxide were produced during reperfusion, and ATP-sensitive potassium channels (K(ATP)), especially mitochondrial ATP-sensitive potassium channels (mitoK(ATP)), are involved in the increased vulnerability. Post-ischemic inhibition of NOS and treatment with a NO scavenger attenuated the increased vulnerability to reperfusion-induced VT/VF, but post-ischemic treatment with a superoxide scavenger did not. In addition, post-ischemic treatment with S-nitroso-N-acetyl-DL-penicillamine (SNAP), a NO donor, or with diazoxide, a selective opener of mitoK(ATP), increased the VT/VF duration during reperfusion. The increased vulnerability to VT/VF was attenuated by the treatment with a selective mitoK(ATP) blocker. CONCLUSION: The results suggest that a pre-ischemic, sustained inhibition of NOS increases the vulnerability to reperfusion-induced VT/VF, and the NO-mitoK(ATP) pathway is one of the possible factors contributing to the increased vulnerability to VT/VF.  相似文献   

20.
目的探讨自噬水平变化对心脏骤停心肺复苏(CA/CPR)后大鼠海马神经元凋亡的影响。方法将40只大鼠随机分为假手术组(sham)、CA/CPR模型组(model)、雷帕霉素(Rapa)组(CA/CPR+Rapa)及3-甲基腺嘌呤(3-MA)组(CA/CPR+3-MA)。采用呼气末夹闭气管窒息法复制大鼠CA/CPR动物模型,分别给予自噬激动剂Rapa 0.2 mg/kg及自噬抑制剂3-MA 10 mg/kg进行干预。采用神经功能缺陷评分(NDS)评价CA/CPR大鼠神经功能;用TUNEL染色法检测大鼠海马神经元的凋亡变化;用RT-PCR和Western blotting法检测大鼠海马内微管蛋白轻链3(LC3)、Beclin-1、Bax、Bcl-2及Caspase-3 mRNA和蛋白的表达水平。结果与假手术组比较,CA/CPR模型组大鼠NDS评分明显降低;海马神经元TUNEL染色阳性细胞数明显增多,凋亡率显著升高;海马内LC3、Beclin-1、Caspase-3、Bax表达上调,Bcl-2表达下调(P<0.05,P<0.01)。与模型组比较,CA/CPR+Rapa大鼠NDS评分明显降低,而海马神经元凋亡率明显有所增加,海马内LC3、Beclin-1、Caspase-3、Bax表达明显上调,而Bcl-2表达则明显有所下降;CA/CPR+3-MA大鼠NDS评分明显升高,而海马神经元凋亡率下降,海马内LC3、Beclin-1、Caspase-3、Bax表达明显下调,而Bcl-2表达则有所升高(P<0.05,P<0.01)。结论 CA/CPR后自噬水平升高促进海马神经元凋亡,自噬水平降低抑制海马神经凋亡,两者相互作用共同参与CA/CPR的病理过程。  相似文献   

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