ISSN:0892-1059    

DOI:10.1111/j.1540-8167.1988.tb01488.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

The efficacy of flecainide (100–150 mg bd) in comparison with atenolol (50–100 mg bd) in suppressing frequent (5/hour) ventricular ectopic activity and nonsustained ventricular tachycardia on ambulatory monitoring was assessed in 26 patients one month after myocardial infarction in a randomized, double‐blind trial. Blood drug levels were monitored and monthly follow‐up ambulatory monitoring and exercise testing were performed for three months, A successful response (70% suppression of ectopic activity or elimination of ventricular tachycardia) was seen in 100% of patients randomized to flecainide compared with 50% randomized to atenolol (p<.05). Three patients developed serious adverse reactions to treatment, one of whom was receiving flecainide and the other two atenolol. The patient on flecainide suffered an exacerbation of heart failure; one on atenolol experienced bronchospasm and the other a proarrhythmic effect. Flecainide is superior to atenolol in the suppression of ventricular ectopics and nonsustained ventricular tachycardia in patients with recent myocardial infarction, though should be used with care in patients with critically impaired left ventricular f

ISSN:0892-1059    

DOI:10.1111/j.1540-8167.1988.tb01489.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

The incidence of proarrhythmia with antiarrhythmic agents is reported to be 2%‐23%, depending on the agent, definition of proarrhythmia, method of assessment, and severity of underlying rhythm disturbance. Several case reports of amiodarone‐induced proarrhythmia have appeared; however, its prevalence and clinical significance have not been adequately defined. In our series of 107 patients with potentially lethal ventricular arrhythmias, amiodarone was administered as a 5‐mg/kg bolus infusion, followed by 600–800 mg/day for 7–10 days. A mean daily maintenance dose of 270 mg/day was given for an average of 15 months (range<57). Proarrhythmia was defined by the method of Morganroth as: (1) a three‐ to tenfold increase in VPC frequency, (2) a marked increase in VT rate, or (3) the development of new sustained VT/VF or torsade de pointes. Bradyarrhythmias, conduction delays, and out‐of‐hospital sudden death were not included by definition. Baseline 24‐hour‐Holter monitoring revealed 449 ± 685 VPCs/hr, 740 ± 584 couplets/24 hr, and 61 ± 685 episodes of nonsustained VT/24 hr. Proarrhythmia occurred in three patients (2.8%). Two of these episodes occurred during the first week of treatment and resolved without dosage adjustment. These episodes included a 4.7‐ and 5.1‐fold increase in VPC frequency. The other proarrhythmic event was a case of torsade de pointes that occurred after 12 months of treatment and required acute intervention and withdrawal of amiodarone. In conclusion, low‐dose amiodarone appears to have a low potential for proarrhythmia and compares favorably with other agents in this regard, perhaps owing to its unique e

ISSN:0892-1059    

DOI:10.1111/j.1540-8167.1988.tb01490.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

Two patients with digitalis toxicity had markedly irregular accelerated idioventricular rhythms that were parasystolic in nature. The relatively abrupt appearance of extrasystoles with different morphologies resulted in patterns of the so‐called rapid and “slow” bidirectional ventricular tachycardias.The parasystolic rhythms seemed to have been classic rather than modulated since nonparasystolic beats occurring in different moments of the cycle failed to affect the latter in the expected, predictable manner. It is possible for the existence of marked, spontaneous variations of the degree of automatic activity to interfere with the diagnosis of parasystolic modul

ISSN:0892-1059    

DOI:10.1111/j.1540-8167.1988.tb01491.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

The implications of ventricular fibrillation induced during elect rophysiologic testing are unclear. To determine the profile of patients in whom this arrhythmia occurs and to determine whether it has any prognostic value, follow‐up data were obtained on all patients in whom this arrhythmia was in duced in our laboratory during a ventricular stimulation protocol over an 18‐month period. Of 836 patients tested, 29 (27 men and 2 women) had inducible ventricular fibrillation. Most (52%) had coronary disease and 12 (41%) had suffered a prior myocardial infarction. All but 3 had some form of heart disease. Sixteen (55%) had abnormal left ventricular function. Eleven (38%) presented with spontaneous sustained ventricular tachycardia or ventricular fibrillation. Eight others had a history of nonsustained ventricular tachycardia.Follow‐up was obtained for a mean of 12 months.In spite of therapy, 2 patients died an arrhythmic death, 1 was resuscitated from ventricular fibrillation, 1 had spontaneous sustained ventricular tachycardia, 4 had inducible sustained ventricular tachycardia, 2 continued to have inducible ventricular fibrillation at second study, and 1 had recurrent syncope. Five patients had ventricular fibrillation induced on multiple occasions.Ventricular fibrillation induced during electraphysiologic study was found primarily in patients with structural heart disease and appeared reasonably reproducible. When reproducible, ventricular fibrillation appears to indicate a poor prognosis rather than an aspecific finding. The clinical profile of our poor prognosis group includes a history of prior ventricular tachycardia or ventricular fibrillation and the presence of coronary artery di

ISSN:0892-1059    

DOI:10.1111/j.1540-8167.1988.tb01492.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

Atrioventricuiar (AV) ablation to yield chronic first degree block was attempted in six mongrel dogs. Radio frequency energy (RFE) at 750 KHz, ranging from 3.4 to 4.5 W, was delivered from the distal pole of a USCI 6F quadripolar electrode catheter to a site near the AV node. RFE delivery times ranged from 5 to 60 sec and were repeated in each animal tintil the PR interval was prolonged by 25% or more, if possible. Immediately after ablation, during autouomic blockade, 5 of the 6 dogs had PR‐interval prolongation of 25% or more, averaging 36%. The mean PR prolongation in 4 of these dogs was +41% at 1 week, +50% at 1 month ami +50% at 4 months after ablation in the absence of autonomic blocking agents and +54%, +42%, and +44%, respectively, for the same periods after autonomic blockade. The fifth dog had less than 20% increase in PR during subsequent measurements and the sixth dog experienced permanent third degree block after multiple KFE shocks. In the 4 dogs with chronic PR prolongation, the maximum damage was found in the approaches to and in the AV node, less in the His bundle, and least in the bundle branches. It is concluded that chronic modification of AV conduction can be produced in a majority of dogs with RFE with lesions located in the approaches to the AV node and at the AV node, with minimal or moderate involvement of surrounding tissue

ISSN:0892-1059    

DOI:10.1111/j.1540-8167.1988.tb01493.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

Although coronary artery bypass graft surgery is frequently performed in patiejits with permanent ventricular pacemakers, the effects of pacemaker generator stimuli during cardioplegic arrest are unknown. This study was undertaken to detennine whether, during cardioplegic arrest in the presentee of a coronary occlusion, pacemaker stimuli accentuate postischemic LV damage.Twelve pigs were placed on cardiopulmonary bypass and subjected to 80 min ofischemic arrest with multiple doses of crystalloid potassium crystalloid caidioplegia supplemented with topical and systemic (28C) hypothermia. During arrest, the mid LAD was occluded with a snare that was released upon reperfusion. In all animals, epicardial ventricular pacing wires were placed and capture was confirmed. In 6 pigs, pacing was instituted prior to ischemic arrest and continued throughout the ischemic and postischemic periods. Six other pigs were not paced and served as controls.Pacemaker stimuli during arrest had no effect on LV temperature. There was no difference in postischemic Lt mass, compliance curves, wall‐motion scores, or stroke xvork itidex between the paced and nonpaced hearts.We conclude that sustained pacemaker stimuli during cardioplegic arrest does not impair global and regional postischemic LV functio

ISSN:0892-1059    

DOI:10.1111/j.1540-8167.1988.tb01494.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

A computer model has been developed which simulates both excitation and recovery processes within a block of heart muscle tissue. The model emphasizes the electro physiologic features of repolarization processes. It is comprised of artificial images of myocardial tissue consisting of several thousand elements and introduces phenomena that are omitted or seriously simplified in most of the existing computer models of cardiac electrophysiology. These phetiomeria include the abnormal shapes of action‐potential curves corresponding to premature excitation of cells that have not fully recovered, different durations of the repolarization phase in endoepicardial layers of tissue, and the tissue anisotropy of excitation transmission and electric resistivity.The model has been used in several experiments. Results of simulation studies are presented in the form of modelled 3‐lead electrocardiographic records. In spite of simple assumptions used at model construction, the results of simulation experiments reproduce natural phenomena. The experimental series include: simulation of regular activation sequences, models of ischemia and infarction, models of pnemature beats, simulation of effects due to fast sequential excitation, and simulation of reentry mechanisms with special reference to the initiation of ventricular fibrillation.The future development of more realistic models of cardiac recovery processes is also discus

ISSN:0892-1059    

DOI:10.1111/j.1540-8167.1988.tb01495.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

Current antitachycardia systems such as the automatic implantable cardioverter/defibrillator (AICD), detect tachyarrhythmias primarily by sensing rate and thereby perform inadequately in differentiating hemodynamically stable from unstable arrhythmias. As a result, these devices may discharge during stable tachycardias (such as sinus tachycardia), causing discomfort to the patient and depleting the device's limited energy supply. If a parameter which could reflect the particular hemodynamic state of a tachycardia were incorporated into the sensing algorithm of these systems, function may be more hemodynamically precise and discharge specificity may be improved.

ISSN:0892-1059    

DOI:10.1111/j.1540-8167.1988.tb01496.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

This report describes an attempt to treat recurrent ventricular tachycardia by catheter electrode ablation. The procedure failed to control the arrhythmia and resulted in a Q‐wave anteroseptal myocardial infarction. The potential complications of catheter electrode ablation in the normal ventricle are emphasize

ISSN:0892-1059    

DOI:10.1111/j.1540-8167.1988.tb01497.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY