Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0042510 (ventricular fibrillation)
 10,091 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We examined, a 64 year old man with hypertrophic nonobstructive cardiomyopathy (HNCM) accompanied with dizziness. Twenty-four hour ECG monitoring showed sinus bradycardia and sinoatrial block. Electrophysiologic study demonstrated inducible sustained ventricular tachycardia (VT) by continuous rapid high right atrum pacing during which systolic blood pressure fell to 40 mmHg. Induced VT degenerated into ventricular fibrillation in ten seconds. We implanted a DDD pacemaker for sick sinus syndrome (SSS) and administrated 90mg/day of diltiazem for VT. Treadmill exercise test was carried out while the patient was taking diltiazem and no arrhythmia was induced. This case of HNCM is rare in that he presented both sick sinus syndrome and sustained VT.
 ...
PMID:[A case of nonobstructive hypertrophic cardiomyopathy associated with ventricular tachycardia and sick sinus syndrome]. 143 57

Radiofrequency current is being investigated as an alternative to direct current shock for transcatheter ablation of cardiac arrhythmias. Permanent pacemakers are known to be susceptible to high frequency electromagnetic interference. This study was performed to examine the effects of transcatheter radiofrequency ablation on permanent pacemakers in a worst-case scenario. Nineteen pulse generators representing 16 models from seven manufacturers were acutely implanted in 12 dogs to assess their function during and after ablation. Pulse generators were implanted subcutaneously in the neck and connected to a transvenous permanent pacing lead positioned in the right ventricular apex. A 6F quadripolar electrode catheter was positioned approximately 1 cm from the tip of the permanent pacing lead. Radiofrequency current from an electrosurgical unit was applied between the distal electrode of the catheter and a large diameter skin electrode placed below the left scapula. Three additional ablation sessions were performed with the catheter situated 4-5 cm from the permanent pacing lead. Each ablation consisted of 15 W of radiofrequency power, delivered for up to 30 seconds. Twelve pulse generators were falsely inhibited during radiofrequency ablation while programmed to the VVI or DDD mode, nine of which continued to be inhibited while programmed to the VOO or DOO mode. Five pulse generators paced at abnormal rates, including three examples of one pulse generator model that displayed pacemaker runaway. Runaway was observed during eight ablations, resulting in two episodes of ventricular fibrillation. Eleven pulse generators reverted to noise mode behavior during ablation. Only three pulse generators were unaffected during ablation. No reprogramming or pacing system malfunctions were observed after cessation of radiofrequency current application or during ablations greater than 4 cm from the permanent lead.(ABSTRACT TRUNCATED AT 250 WORDS)
 ...
PMID:The effect of radiofrequency catheter ablation on permanent pacemakers: an experimental study. 168 30

The authors described an operation performed in a female patient aged 37 years who was first examined in 1980. That year she experienced the first ventricular fibrillation episode. The duration of the Q-T interval was 600 msec. She was examined by a comprehensive protocol which enabled coronary abnormalities to be excluded. The operation was made in July 1987 in the Charite Hospital by Dr. Warnke. The operation involved dissection of the nerve connections nearest the heart by cutting the pulmonary artery, aorta, both atria and subsequently suturing by the scheme used in cardiac grafting. The patient rapidly recovered after the surgery. She had a normal Q-T interval and no recurrences of ventricular tachycardias. Following the surgery she displayed disturbances of intraatrial conduction and pacemaker displacement into the lower segments of the right atrium, so she was implanted a DDD-mode pacemaker.
 ...
PMID:[Treatment of tachyarrhythmia in a patient with long QT syndrome by autologous heart transplantation and atrial stimulation controlled by the sinoatrial node]. 208 42

The term "synchronous pacemaker (SPM)" is used to describe all pacemakers of which the frequency can be accelerated by means of a sensor other than the sinus node. The most commonly used system is the detection of changes in physical activity by means of a quartz crystal included in the casing. Changes in respiratory volume, the respiratory rate, the QT interval or central temperature have been less successfully used. Single and double-chamber (DC) synchronous pacemakers exist. Ventricular single-chamber synchronous pacemakers (VVIR) are primarily intended for active patients in a state of chronic atrial fibrillation or, secondarily, in cases in which the insertion of an atrial electrode raises difficulties. The single-chamber atrial synchronous pacemaker (AAIR), or preferably the double-chamber equivalent (DDDR) is intended for the correction of chronotropic failure, whether this is primary or induced by bradycardiac antiarrhythmic medication. AVB should be treated by double-chamber simulation designed to pick up P waves. The value of the synchronous pacemaker in these patients is that it makes it possible to partially offset the loss of atrial systole in cases of ventricular fibrillation by a synchronous pacemaker (pacemaker programmed to shift from DDD to VVIR). The setting of the SPM is fairly complex and calls for exercise tests. Iatrogenic acceleration is not unusual and must be identified by long-term recordings. All these pacemakers will here include a "synchronous" option, which may be of variable efficacy. It is up to the clinician to use them appropriately, and not automatically, remembering that the best sensor is the sinus node and that synchronous pacemakers are only second best.
 ...
PMID:[Rate-responsive cardiac pacing]. 229 12

Three patients are reported whose DDD pacemakers reverted to the asynchronous mode in the absence of skeletal muscle or electromagnetic (EMI) interference. In all three cases, the basic cardiac rhythm was atrial fibrillation with fast ventricular response due to intrinsic AV conduction. Noise reversion was triggered by the patients' own ventricular activity at cycle lengths shorter than the ventricular refractory period of the pulse generator. In one patient, asynchronous AV sequential pacing during atrial fibrillation was noted shortly after resuscitation from ventricular fibrillation; however, the initiation of the malignant ventricular arrhythmia by the pacemaker remains unproven. The mechanism of noise reversion by rapid cardiac activity and possible solutions to the problem by adequate pacemaker design are discussed.
 ...
PMID:Noise reversion of a dual chamber pacemaker without noise. 242 75

Forty-one children, 20 boys and 21 girls, aged 11 days to 19 years (mean 9.9 years) at initial pacemaker implant, were followed 1 to 248 months (mean 90 months). Ten (mean age 8.2 years) were implanted between 1966 and 1972 (Group I), 14 (mean age 9.9 years) between 1973 and 1980 (Group II) and 17 (mean age 10.9 years) from 1981 through April 1988 (Group III). Arrhythmias were congenital complete heart block in 19, postoperative heart block in 15, acquired heart block in 3, sick sinus syndrome in 3, and bradycardia-induced ventricular fibrillation in 1. Twenty-eight of 41 children had a transvenous implant: 40% of Group I, 71% of Group II and 82% of Group III. Thirteen were cephalic, four subclavian and 11 jugular. Generator site was pectoral in 19, abdominal in 12, intrathoracic in one, and retromammary in nine of 12 girls aged 10 years or more at implant. In Groups I, II and III, 5, 14 and 6 had VOO or VVI units; 5, 0 and 8 dual chamber (VAT, VDD and DDD) pacemakers; 0, 0 and 1 AAI; and 0, 0 and 2 rate-modulated (VVIR) units at initial implant. The average interval between pacer-related hospitalizations in Groups I, II and III was 20, 42, and 39 months. Complications included infection in six, hemothorax in one, and impending pacemaker erosion in one. Six patients died, one of pacer infection, four from primary cardiac disease, and one suddenly without apparent reason. Follow-up continues in 31: 14 are employed full-time, three are homemakers, eight are full-time students, and six are active pre-schoolers.(ABSTRACT TRUNCATED AT 250 WORDS)
 ...
PMID:Pacemaker implantation in children: a 21-year experience. 246 70

136 patients were followed after implantation a DDD pacemaker (PM) for a total of 1,919 patient-months (m = 14.1 months/patient). 22/136 patients had one or more episodes of atrial flutter or fibrillation (AF) postoperatively. In 121/136 patients (group A) AF had not been documented before, in 4 it was unknown at the time of implantation, but was verified retrospectively (group B). 11 patients (group C) had a positive history of previous AF. Post implantation 7.4% in group A and 81.8% in group C developed AF. In patients with sick sinus syndrome (SSS) the incidence was 10/37 (27%), in those with AV block (AV) 6/77 (7.8%) and in cases with both SSS and AV 6/22 (27.3%). The first AF episode occurred during the implantation itself (n = 2) or during the hospital course in 9/22 patients (A: 11%, B/C: 64% early attacks), and later on in 13 with a time delay of 1-24 months (m = 8.5, 8 patients) in group A and 2-15 months (m = 6.6, 4 patients) in groups B/C. 2 patients of group C had no AF episodes post implantation. In the individual patient the number of attacks ranged from 1 to 3 (10.4/100 patient-months) in group A and from 1 to 6 (20.1/100 patient-months) in groups B/C. During AF 16/22 patients had a ventricular rate of 110-185, m = 132 bpm. In 6 patients the tachycardia was mediated by the PM and in 10 by fast intrinsic AV conduction. 1 patient with SSS, 2 with SSS + AV (spontaneous ventricular rate less than 45 bpm) and 3 with AV needed ventricular backup-pacing during AF. In 7 patients a total of 15 attacks of atrial flutter could be terminated by atrial overdrive pacing, in 5 of these episodes by temporary high rate A00 stimulation via the implanted pacemaker lead system. Otherwise AF was converted to sinus rhythm by antiarrhythmic drugs. After termination AF often recurred, but only 3 patients developed chronic atrial fibrillation. In 2 patients a ventricular rate greater than 180 bpm during AF reverted the PM to asynchronous mode, a possible cause of ventricular fibrillation in one. No other complications due to the PM itself have been encountered. AF, therefore, common during DDD pacing, even in patients without any AF history before implant. Both the incidence and the recurrence of AF depend on the presence or absence of previous atrial arrhythmias.(ABSTRACT TRUNCATED AT 400 WORDS)
 ...
PMID:[Atrial flutter and atrial fibrillation by DDD stimulation]. 406 Aug 30

To evaluate the complication rate during AV universal pacing (DDD), 41 consecutive patients with complete heart block were studied and followed up for 2-30 (mean 10.8) months. The Cordis Sequicor Theta was used in 6 patients and the Siemens-Elema 674 in 35. Clinical problems related to the pacemaker treatment occurred in 12 patients (pacemaker tachycardia triggered by retrograde atrial activation in 2, atrial oversensing in 3 and undersensing in 2, ventricular oversensing in 2 and undersensing in 1). Ventricular fibrillation occurred during threshold measurement in one patient. Seven of the problems could be ascribed to the DDD mode. Four of these 7 problems could be solved by reprogramming the pacemaker. A nonprogrammable atrial refractory period in the Cordis Sequicor was found to be a limitation in patients with endless loop tachycardia. In 3 cases reoperation had to be performed. In another 3 cases there were problems with ventricular sensing which in one could be solved by reprogramming. Apart from ventricular fibrillation, which could not be ascribed to the DDD mode, there were no serious problems in the clinical management of the patients.
 ...
PMID:Incidence and management of pacemaker-related complications during dual-chamber pacing. 407 75

Ventricular fibrillation has been only rarely observed as a complication of cardiac pacing after the advent of demand pacemakers. Automatic AV sequential pacing (DDD) may provide the setting for ventricular fibrillation in patients with junctional rhythms. In this report we present two patients with implanted DDD pacemakers in whom ventricular pacemaker spikes were seen occurring on top of the T wave during episodes of junctional rhythm. This apparent lack of sensing of QRS complexes does not represent pacemaker malfunction, but rather, is the result of physiologic lack of sensing (blanking) which occurs 56 to 100 msec. following the output of the atrial and ventricular channels. During junctional rhythm when the atrial spike occurs at the beginning of a QRS complex the ventricular channel is blanked and does not sense the intrinsic ventricular activity and thus, ventricular output occurs during repolarization. Increasing the maximum pacemaker rate and decreasing the AV delay will reduce the chance occurrence of this phenomenon.
 ...
PMID:Pseudo failure of sensing in patients with universal pacemakers and junctional rhythms. 673 46

A bipolar DDD pacemaker system was implanted in a 51-year-old woman with a 2 degrees (Mobitz type) atrioventricular block. The first postimplantation control was unremarkable, but she collapsed 9 weeks later with dyspnoea, tachycardia and profound perspiration. Ventricular flutter occurred twice during routine ambulatory pacemaker function tests one week later. The first episode was terminated by a precordial blow with a fist, but the second required electrical defibrillation. During the subsequent hospitalization abnormal electrolyte balance and digitalis intoxication were excluded. Left-heart catheterization with coronary angiography showed normal left-ventricular function at rest and normal coronary arteries. There was no evidence for an arrhythmogenic right ventricle. Electrophysiological testing with programmed ventricular stimulation provoked ventricular tachycardia with torsade de pointes and transition to ventricular fibrillation. Antiarrhythmic treatment with sotalol, 160 mg twice daily by mouth, failed to suppress the episodes of torsade de pointes. But further programmed ventricular stimulation was uneventful after the sotalol dosage had been increased to 160 mg three times daily.
 ...
PMID:[Reproducible ventricular flutter during programming of a DDD pacemaker]. 828 79


1 2 Next >>