A 17 year experience of inappropriate shock therapy in patients with implantable cardioverter-defibrillators: are we getting any better?
Explore the source record for details and available documents.
Arrhythmias, Cardiac↗
Biomedical subjects
J Bostock
Publications and source records attributed to J Bostock.
Determinants of procedural outcome of chronically implanted pacemaker and defibrillator leads using the Excimer laser sheath.
Explore the source record for details and available documents.
Angioplasty, Balloon, Laser-Assisted↗
Atrial flutter ablation: efficacy and cost-effectiveness of a single decapolar electrode to demonstrate bidirectional isthmus block.
AIMS: To evaluate whether a single decapolar electrode is a reliable and cost-effective substitute for the 'Halo' catheter to map the circuit and detect bidirectional isthmus block during atrial flutter (AFL) ablation. METHODS AND RESULTS: Twenty-four patients underwent AFL ablation by using the decapolar electrode in the infero-lateral wall of right atrium (group A) while a 'Halo' catheter was used in 11 patients (group B). Both groups had similar clinical characteristics. Anti-clockwise rotation (20 patients), clockwise (3 patients) or both forms of AFL (1 patient) were detected in group A. All patients in group B had anti-clockwise AFL. Bidirectional isthmus block was completed in 22 patients of group A and in 9 of group B (P=NS) while incomplete isthmus block was detected in 2 patients in each group (P=NS). Mean fluoroscopy and procedure time was 27 +/- 47 min, 107 +/- 36 min in group A and 14 +/- 19 min, 114 +/- 65 min in group B (P=NS). AFL relapsed in 3 patients of group A (follow-up 7 +/- 4 months) and in 2 of group B (4 +/- 2 months). CONCLUSION: A single decapolar electrode is a reliable method to map the circuit and demonstrate bidirectional isthmus block during AFL ablation. The cost of the decapolar electrode is a quarter of that of the 'Halo' catheter. This represents a significant saving particularly for centres with a substantial number of AFL ablations.
Adult↗
Unguarded tricuspid orifice with pulmonary atresia: successful radiofrequency ablation of an accessory pathway in an infant.
A male infant with the rare lesion of unguarded tricuspid orifice in the setting of pulmonary valve atresia, intact ventricular septum, and a hypoplastic right ventricle is described. The patient presented with cyanosis at 1 day old; transcutaneous oxygen saturations were between 20% and 30% in room air, and 60% in 100% inspired oxygen. Pre-excitation was found incidentally on the ECG and the potential for rapid antegrade conduction of atrial tachyarrhythmias, after eventual extended palliation with the Fontan procedure, was demonstrated at electrophysiological study. By 11 months old the patient was becoming increasingly cyanosed and interim palliation with a bidirectional cavopulmonary shunt was proposed. Successful radiofrequency ablation of the accessory pathway was performed before bidirectional cavopulmonary shunt, which would have prevented access to the heart via the superior vena cava. Difficulty with femoral venous access because of previous occlusion of a femoral vein was overcome by the use of 2 F pacing electrodes and a 5 F ablation catheter.
Catheter Ablation↗
Single pass VDD pacing in children and adolescents.
Use of a single pass lead for VDD pacing in complete heart block is well described in adults, but there are only brief reports of its use in children. We have used standard adult size single pass leads in 13 children and adolescents aged 3.7-17.2 years (mean 10.1 years) and weighing 13.5-76 kg (mean 34.8 kg). Congenital complete heart block was present in 7 patients, surgical complete heart block in 5 patients and 2:1 AV block of unknown cause in 1 patient. In four patients, the VDD system was their first pacing system. In nine of the patients, 1-6 previous systems had been used and simultaneous extraction of ventricular leads and/or atrial leads was performed. Leads of four different types were used: Brilliant IMP15Q, Brilliant + IMR15Q, CapSure 5032, and Unipass 425-13 with 4 different generators: Saphir 600, Saphir II 620, Thera VDD 8948, and Unity 292-07. At implantation, via a subclavian vein puncture, excess lead was advanced into the right atrium to allow both atrial sensing and slack for further growth. Ventricular thresholds ranged from 0.2-0.7 V. The minimal atrial amplitude was 0.7-4 mV and the maximum amplitude was 2.5-8 mV. There were no complications. All patients have maintained adequate atrial signals for reliable pacing with follow up of 3-36 months (mean 17.6 months) during which time some have undergone considerable growth. Reliable atrial synchronous ventricular pacing is possible in growing children with complete heart block using a standard adult single pass lead.
Adolescent↗
VDD pacing in children with congenital complete heart block: advantages of a single pass lead.
A single pass lead for VDD pacing in complete heart block is well described in adults but there are only brief reports of its use in children. We used standard adult size single pass leads in ten children and adolescents aged 3.7-17.2 years (mean 9.9 years) and weighing 13.5-76 kg (mean 35.4 kg) with congenital complete heart block. One patient had coexisting congenital heart disease and had undergone surgery. A 2:1 atrioventricular block in one patient was presumed to be congenital in origin. In four patients, the VDD system was their first pacing system. In six of the patients, 1-4 previous systems had been used and simultaneous extraction of ventricular leads (6) and/or atrial leads (2) was performed. Four different types of lead were used: Brilliant IMP15Q (Vitatron); Brilliant + IMR15Q (Vitatron); CapSure 5032 (Medtronic); and Unipass 425-13 (Intermedics) with four different generators: Saphir 600 (Vitatron); Saphir II 620 (Vitatron); Thera VDD 8948 (Medtronic); and Unity 292-07 (Intermedics). All leads were introduced via a subclavian vein puncture and the atrial dipole was placed low in the right atrium to provide slack for further growth while maintaining atrial sensing. Ventricular thresholds ranged from 0.2-0.8 V. The minimal atrial amplitude was 0.7-4 mV and the maximum amplitude was 2.5-8 mV. There was one early microdisplacement and the lead was repositioned. Over a follow-up period ranging from 1-39 months (mean 20.4 months), all patients have maintained low ventricular pacing thresholds and adequate atrial signals for reliable pacing at rest and with exercise. During this time some have undergone considerable growth. The patient with coexisting congenital heart disease died suddenly at 3 years, but the pacing system had no fault at autopsy. The standard adult size single pass lead provides a simple means to enable reliable atrial synchronous ventricular pacing in growing children with complete heart block.
Adolescent↗
Use of an atrial loop to extend the duration of endocardial pacing in a neonate.
Use of an atrial loop has been proposed as a means of extending the longevity of endocardial pacing systems in small children who require ventricular pacing. A few reports have demonstrated the effectiveness of this method at reducing the number of interventions in infants and small children, but there is little reported experience in neonates. Permanent endocardial ventricular demand pacing was performed in a 3.4-kg neonate. The generator was placed in a prepectoral pocket and a redundant loop of lead was left in the atrium to cater for further growth. At 32 months he weighs 13.6 kg and the loop has uncoiled leaving additional lead slack for further growth.
Endocardium↗
Iatrogenic atrioventricular bypass tract following a Fontan operation for tricuspid atresia.
A 16 year old female with tricuspid atresia had undergone a Fontan operation at four years of age. Two years later she first presented with a narrow complex tachycardia which could only be partially controlled on flecainide in high doses. On electrophysiological study, the tachycardia was found to be due to atrioventricular re-entry within the surgical right atrial to right ventricular outflow tract anastomosis. Radiofrequency ablation at this site abolished the arrhythmia and she is now symptom-free on no medication.
Adolescent↗
Dual sensor VVIR mode pacing: is it worth it?
Dual sensor ventricular demand rate responsive (VVIR mode) pacing was compared with single sensor rate responsive pacing to assess whether this new development should be more widely incorporated in modern pacemaker devices. A within patient randomized, double-blind crossover study involving ten patients, mean age 67.4 years (70% male), had Medtronic Legend Plus dual sensor VVIR pacemakers implanted for high grade AV block and chronic or persistent paroxysmal atrial fibrillation. Performance values were compared to 20 healthy control subjects of a similar age and gender. Patients were both subjectively and objectively assessed after 2 weeks of out-of-hospital activity in VVIR mode (minute ventilation sensing), VVIR mode (activity sensing), VVIR mode (dual sensor), and VVI mode (no rate response). All patients were assessed for subjective preference for, and objective improvement in, any pacing modality as assessed by standardized daily activity protocols and graded exercise treadmill testing. Subjective perception of exercise capacity and functional status was significantly lower in VVI mode (P < 0.05) compared to any of the VVIR modes, which did not differ. After completion of the study 70% of patients chose VVIR as their preferred mode, with 30% expressing no preference. Forty percent preferred activity sensor VVIR mode pacing, 30% preferred dual sensor VVIR mode pacing, and 70% found either dual sensor VVIR mode, minute ventilation sensor VVIR mode, or both modalities least acceptable. No patient found activity sensing VVIR mode least acceptable. Graded treadmill testing revealed significantly lower exercise tolerance during VVI mode pacing (P < 0.01) compared to the VVIR modalities, which did not differ. Overall, chronotropic response was best with dual sensor pacing during standardized daily activity protocols and during the standard car journey. The data from this study suggest that there is no marked clinical advantage obtained from the use of dual sensor devices over current activity sensing ventricular demand rate responsive pacemakers, but with the probable added disadvantages of increased size, complexity, cost, and decreased longevity.
Activities of Daily Living↗
Pacemaker upgrade for recurrent pacemaker syndrome using a redundant contralateral electrode in a patient with bilateral venous stenoses.
Following His-bundle ablation and VVIR pacemaker implantation, severe pacemaker syndrome developed and was treated with DDDR pacing, in a 70-year-old woman. Due to bilateral subclavian vein stenoses, DDDR pacing could not be maintained and an unusual method of restoring atrioventricular synchrony is described using the contralateral redundant atrial electrode connected to the ipsilateral dual chamber pacemaker and ventricular electrode.
Aged↗
Pacemaker upgrade for recurrent pacemaker syndrome using a redundant contralateral electrode in a patient with bilateral venous stenoses.
Following His-bundle ablation and VVIR pacemaker implantation, severe Pacemaker syndrome developed and was treated with DDDR pacing in a 70-year-old woman. Due to bilateral subclavian vein stenosis, DDDR pacing could not be maintained and an unusual method of restoring atrioventricular synchrony is described using the contralateral redundant atrial electrode connected to the ipsilateral dual chamber pacemaker and ventricular electrode.
Aged↗
"Subclinical" pacemaker syndrome: a randomised study of symptom free patients with ventricular demand (VVI) pacemakers upgraded to dual chamber devices.
OBJECTIVE: To determine whether symptom free patients with single chamber pacemakers benefit from dual chamber pacing. DESIGN: A randomised double blind crossover comparison of ventricular demand (VVI), dual chamber demand (DDI), and dual chamber universal (DDD) modes after upgrading from a VVI device. SETTING: Cardiology outpatient department. PATIENTS: Sixteen patients aged 41-84 years who were symptom free during VVI mode pacing for three or more years. INTERVENTION: Pacemaker upgrade during routine generator change. MAIN OUTCOME MEASURES: Change in subjective (general health perception, symptoms) and objective (clinical assessment, treadmill exercise, and radiological and echocardiographic indices) results between pacing modes before and after upgrading. RESULTS: 75% preferred DDD, 68% found VVI least acceptable with 12% expressing no preference. Perceived general well-being and exercise capacity (p less than 0.01) and treadmill times (p less than 0.05) were improved in DDD mode but VVI and DDI modes were similar. Clinical, echocardiographic, radiological, and electrophysiological indices confirmed the absence of overt pacemaker syndrome, although mitral and tricuspid regurgitation was greatest in VVI mode (p less than 0.01). CONCLUSIONS: Most patients who were satisfied with long term pacing in VVI mode benefited from upgrading to DDD mode pacing suggesting the existence of "subclinical" pacemaker syndrome in up to 75% of such patients. The DDI mode offered little subjective or objective benefit over VVI mode in this population and should be reserved for patients with paroxysmal atrial arrhythmias. VVI mode pacing should be used only for patients with very intermittent symptomatic bradycardia or atrial fibrillation with a good chronotropic response during exercise.
Adult↗
Inappropriate discharges by the implantable cardioverter defibrillator during postoperative testing: implications for intraoperative assessment.
Inappropriate shocks were delivered to a patient while in sinus rhythm by an implantable cardioverter defibrillator (ICD) during routine prehospital discharge testing. This was induced by the standard programmer when the "read" telemetry sequence was initiated. The ICD was removed and found to suffer from electrical artifact that was sensed as ventricular tachycardia during telemetry. To avoid inadvertent telemetry-induced shocks during routine testing, all ICDs should be interrogated, using a standard programmer, intraoperatively, with the unit in "defibrillation on" mode.
Aged↗
The 24-hour heart rate behavior in long-term survivors of cardiac transplantation.
A detailed computerized analysis of heart rate (HR) behavior during ambulatory monitoring was performed in 19 long-term survivors of cardiac transplantation (12 orthotopic, 7 heterotopic) and in 10 normal volunteers. Compared with normal hearts, the transplanted denervated and the recipient innervated hearts in the heterotopic group showed higher average HRs over the whole 24 hours, the waking and sleeping periods. The rates of the denervated and the recipient hearts did not differ significantly. The maximal HR was similar in all 3 groups, but the minimal HR was lower in the normal hearts than in denervated and recipient hearts. The 24-hour RR interval variability was greatly reduced in the denervated hearts (60 +/- 22 ms) compared with the recipient (89 +/- 26 ms) and normal (151 +/- 38 ms) hearts. During arousal from sleep, the magnitude, time and rate of the HR change were significantly reduced in the denervated hearts compared with the innervated hearts and in the recipient compared with the normal hearts. These findings demonstrate that denervated hearts can show significant variations in HR during the 24-hour period, but to a lesser extent than normal hearts. The widest deviation from normal occurs during sleep, when the denervated heart shows minimal slowing probably due to lack of parasympathetic innervation. In heterotopic transplant recipients, the patients' own HR responses also are significantly blunted.
Adult↗
Ventricular arrhythmias in long term survivors of orthotopic and heterotopic cardiac transplantation.
Fourteen long term survivors with orthotopic (recipient heart replaced by donor heart) and nine with heterotopic cardiac transplants (recipient heart retained) had 24 hour ambulatory electrocardiographic monitoring to detect ventricular arrhythmias. Arrhythmia was uncommon in the patients with orthotopic transplants; none of them had more than one extrasystole per hour. In the patients with heterotopic cardiac transplants the recipient's own heart showed significantly more frequent ventricular arrhythmias than the corresponding donor heart: abnormal complexes (mean/24 h) 4583 vs 42.7; extrasystoles 1772 vs 17.8; pairs 121 vs 0.8. There was no relation between the abnormal ventricular activity of the two hearts in the patients with heterotopic transplants on a beat by beat, hourly, or 24 hour basis. There was no consistent diurnal variation in the frequency of the abnormal ventricular beats after cardiac transplantation. The occurrence of ventricular arrhythmia was unrelated to the interval from operation to the study. In long term survivors of cardiac transplantation the denervated heart shows a little ventricular ectopic activity even when compared with normal hearts. In patients with heterotopic transplants ventricular arrhythmias commonly occur in the recipient's own heart; these are probably related to the underlying severity of the original disease.
Adult↗
Depressive syndromes in the year following onset of a first schizophrenic illness*.
A complete, unselected series of 68 patients who were seen during their first episode of an undoubtedly schizophrenic illness, and followed up one year later (for 56 patients) is described clinically. Depressive symptoms were common at onset, and 22% of patients could have been considered cases of depression from these symptoms alone. At follow-up, depressive symptoms had reduced in prevalence and only 7% of subjects were depressed cases. Only two cases of depression at follow-up had not been cases at onset. These changes could not be attributed to the use of antidepressants or ECT. Depressive syndromes could be distinguished from akinesia and the negative syndromes. The findings indicate that depression cannot be attributed solely to the administration of neuroleptics.
Adolescent↗
Cardiac rhythm and conduction before and after anatomic correction of transposition of the great arteries.
To assess pre- and postoperative arrhythmias associated with anatomic correction of transposition of the great arteries, 34 patients had 145 standard electrocardiograms (ECGs) and 24 of these patients had 46 24-hour ECGs from 11 months before to 54 months after anatomic repair. Twenty-two patients underwent balloon atrial septostomy and 7 surgical atrial septectomy before the initial 24-hour ECG. Anatomic correction included repair of a large ventricular septal defect in 16 patients and an aortopulmonary window in 1 patient. The preoperative standard ECG showed sinus rhythm in every patient. Preoperative 24-hour tapes revealed sinus arrhythmias in 2, sinus bradycardia at a rate of less than or equal to 50 beats/min in 1, junctional rhythm in 1 and rare premature ventricular contractions (PVCs) in 1. The postoperative 24-hour ECG showed atrioventricular dissociation in 1 patient, rare premature atrial contractions in 7, rare PVCs in 8 and sinus bradycardia with junctional escape in 1. Eight patients had PVCs on the postoperative ECG that were not noted on preoperative tapes. No patient had prolonged bradycardia (less than or equal to 50 beats/min), life-threatening arrhythmias or sudden death. Except for 1 patient with atrioventricular dissociation believed to be secondary to a preventable cause, 34 patients followed for 890 patient-months after anatomic correction for transposition of the great arteries had no significant arrhythmias.
Arrhythmias, Cardiac↗
Letter: Methods of laparoscopic sterilisation.
Explore the source record for details and available documents.
Diathermy↗