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Michael Glikson

Publications and source records attributed to Michael Glikson.

8 recordsLinked to original sources
PubMed2003

Discrepancies between the upper limit of vulnerability and defibrillation threshold: prevalence and clinical predictors.

INTRODUCTION: Upper limit of vulnerability (ULV) has a strong correlation with defibrillation threshold (DFT) in patients with implantable cardioverter defibrillators (ICDs). Significant discrepancies between ULV and DFT are infrequent. The aim of this study was to characterize patients with such discrepancies. METHODS AND RESULTS: The ULV and DFT were determined in 167 ICD patients. Univariate and multivariate analyses were used to evaluate clinical predictors of a significant difference (> or =10 J) between ULV and DFT. Only 8 patients (5%) had > or =10 J difference. ULV exceeded DFT in all of them. Absence of coronary artery disease (6/8 vs 48/159 patients; P = 0.05) and absence of documented ventricular arrhythmias (4/8 vs 12/159 patients; P = 0.01) were the only independent predictors of a significant ULV-DFT discrepancy. CONCLUSION: Significant discrepancies between ULV and DFT occur in 5% of patients with ICDs. Absence of coronary disease and documented ventricular arrhythmias predict such a discrepancy. At ICD implant, DFT testing is recommended in these patients and in patients with a high (>20 J) ULV before first-shock energy and the need for lead repositioning are determined.

Aged↗
PubMed2003

Cardiac resynchronization therapy: a new frontier in the management of heart failure.

CRT offers today another option for some patients with heart failure, side by side with more "traditional" therapies like drugs, assist devices, and heart transplantation. Clinical studies show that in properly selected patients a significant improvement in hemodynamic parameters and clinical status can be achieved by BV pacing. It is still unknown whether this type of therapy will also result in a survival benefit for patients with severe heart failure. The next few years certainly promise to be as exciting for CRT as were the last few.

Cardiac Pacing, Artificial↗
PubMed2002

Noncontact mapping to guide ablation of right ventricular outflow tract tachycardia.

OBJECTIVES: [corrected] The aim of this study was to determine whether noncontact mapping is feasible in the right ventricle and assess its utility in guiding ablation of difficult-to-treat right ventricular outflow tract (RVOT) ventricular tachycardia (VT). BACKGROUND: In patients without inducible arrhythmia, RVOT VT may be difficult to ablate. Noncontact mapping permits ablation guided by a single tachycardia complex, which may facilitate ablation of difficult cases. However, the mapping system may be geometry-dependent, and it has not been validated in the unique geometry of the RVOT. METHODS: Ten patients with left bundle inferior axis VT, no history of myocardial infarction and normal left ventricular function underwent noncontact guided ablation; seven had failed previous ablation and three had received a defibrillator. All noncontact maps were analyzed by a blinded reviewer to determine whether the arrhythmia focus was epicardial and to predict on the basis of the map whether arrhythmia would recur. RESULTS: The procedure was acutely successful in 9 of 10 patients. During a mean follow-up of 11 months, 7 of 9 patients remained arrhythmia-free. Both patients in whom the blinded reviewer predicted failure had arrhythmia recurrence: one due to epicardial origin with multiple endocardial exit sites and one due to discordance between site of lesion placement and earliest activation on noncontact map. CONCLUSIONS: Mechanisms of ablation failure in RVOT VT include absence of sustained arrhythmia, difficulty with substrate localization and epicardial origin of arrhythmia. In this study, noncontact mapping was safely and effectively used to guide ablation of patients with difficult-to-treat RVOT VT.

Adult↗
PubMed2002

Inhibition of biventricular pacemakers by oversensing of far-field atrial depolarization.

This report describes two patients who exhibited far-field oversensing of the P wave by the ventricular channel of a DDD biventricular pacemaker implanted for the treatment of congestive heart failure. Oversensing probably occurred secondary to slight displacement of the left ventricular lead in the coronary venous system. Long-term reliable pacing was restored by decreasing the sensitivity of the ventricular channel.

Aged↗
PubMed2002

ST-segment deviation following implantable cardioverter defibrillator shocks: incidence, timing, and clinical significance.

ST-segment analysis is frequently used during surgical procedures, while ST deviation is considered a sign of myocardial injury. ST deviations were reported following transthoracic and epicardial electrical shocks. The prevalence, timing, and clinical significance of ST-segment deviation following endocardial ICD shocks are discussed in this article. Twenty-eight patients undergoing 125 shock episodes during ICD implantation or testing were included. A 12-lead ECG was recorded at baseline, continuously during the first 3-10 seconds, 1 minute after test shocks, 3-10 seconds and 1 and 5 minutes after each shock given to terminate VF. ST deviation was diagnosed when the ST-segment was displaced > or = 1 mm in at least one lead compared to baseline. ST-segment deviations were observed after 49 (39%) of all shock episodes in 17 (61%) of patients. ST elevation was observed after 30 (24%) of all shock episodes, and ST depression after 31 (25%). Following 13 shock episodes in seven patients, ST-elevation and depression were observed. ST depressions occurred more frequently after shocks given to terminate VF than after lower energy test shocks (28% vs 18% respectively, P = 0.045). However, there was no significant difference in the prevalence of ST elevations between the lower or higher energy shocks. No adverse clinical events were observed in patients with or without postshock ST-segment deviation. ST-segment deviation following endocardial ICD shocks is a frequent phenomenon, occurring acutely and resolving during the first few minutes postshock. It mayhave no prognostic implications.

Defibrillators, Implantable↗
PubMed2002

Multiple pulse generator malfunctions with a dual chamber pacemaker.

The aim of this study was to evaluate the dual chamber uni/bipolarpacemaker Minidual 50, manufactured by Sorin Biomedica. Between 1995 and 1998, 66 Minidual 50 models were implanted at the Heart Institute. During the follow-up period of 33 +/- 12.8 months (range 0-50 months), total function loss in seven (10.6%) units and false threshold measurement of sensing and pacing in three (4.5%) patients were observed. Average time from implantation to malfunction was 37 months (range 28-42). Malfunction was unrelated to battery status and could not be predicted by any measures obtained during the pacemaker follow-up period. Kaplan Meyer survival curve predicted a 70% 4-year malfunction-free survival of that pacemaker model. Given this high rate of total malfunction and the unpredictable nature of its occurrence, the authors recommend the replacement of all remaining Minidual 50 units at risk, at least in dependent patients.

Adult↗
PubMed2002

Impaired detection of ventricular tachyarrhythmias by a rate-smoothing algorithm in dual-chamber implantable defibrillators: intradevice interactions.

INTRODUCTION: Rate smoothing is an algorithm initially designed to prevent rapid changes in pacemaker rates. In this study, we sought to determine the potential of the rate-smoothing mechanism in preventing detection of ventricular tachyarrhythmias. METHODS AND RESULTS: Clinical testing of rate smoothing was performed at the time of defibrillator arrhythmia induction in 16 patients with implantable defibrillators during 65 episodes of ventricular tachyarrhythmias. We also performed simulator-based testing to assess detection of ventricular tachycardia between 170 and 220 beats/min with systematic sequential change of rate-smoothing percent, AV delay, and maximal rate. During clinical testing of 54 ventricular fibrillation/polymorphic ventricular tachyarrhythmia episodes, there were no cases of nondetection and 3 episodes (5%) of minimally delayed detection. Of 10 monomorphic ventricular tachyarrhythmias, 6 had either delayed (2 cases) or absent (4 cases) detection. During simulator testing, complex interrelationships were demonstrated in AV delay, upper rate, and rate-smoothing percent in determining the severity of the effect on detection. Generally, long AV delay, higher upper rate, and smaller (more aggressive) rate smoothing were associated with increased risk of ventricular tachyarrhythmia underdetection. Importantly, use of parameters that impaired detection was always accompanied by a programmer warning message. CONCLUSION: Rate smoothing may result in delay or failure of ventricular tachycardia detection. It is important to consider warning messages when programming rate smoothing and to test for appropriate detection when rate smoothing is used despite warning messages.

Algorithms↗