Aging and Time-Domain and Spectral Turbulence Parameters of Signal-Averaged Electrocardiograms

The effect of age on the time-domain and spectral parameters of the signal-averaged ECG (SAECG) is not known. In this study we recorded SAECGs from 138 normal healthy subjects (84 females and 54 males) aged between 7 and 102 years. The recordings were processed in time-domain and by spectral turbulence analysis. Spearman correlation coefficients were used to assess the relationship among each of the parameters obtained and age in the total population and in the subpopulations of males and females. Linear regression models of individual parameters with age were calculated and compared in males and females. Using conventional diagnostic criteria, 13 recordings (9.4%) were abnormal in time-domain analysis and 13 (9.4%) were abnormal in spectral turbulence analysis. However, no recording was abnormal in both types of analysis, and the incidence of abnormal SAECG was not age dependent. There were significant correlations between age and 4 of the 5 parameters used to evaluate spectral turbulence analysis (low segment correlation ratio [LSCR], intersegment correlation mean, intersegment standard deviation, and spectral entropy [SE]). However, there was no systematic significant correlation between age and time-domain parameters. The values of tQRS, mean peaks per slice, LSCR, and SE indices were significantly higher in males than in females, irrespective of age. The study concludes that with increasing age, there is a tendency for the parameters of spectral turbulence analysis to become abnormal, possibly reflecting an increase in conduction abnormalities with age.     

Comparison of a Unipolar Defibrillation System with a Dual Lead System Using an Enlarged Defibrillation Anode

The unipolar system for transvenous defibrillation, consisting of a single right ventricular lead as the cathode and the device shell as anode, has been shown to combine low de- fibrillation thresholds (DFTs) and simple implantation techniques. We compared the defibrillation efficacy of this system with the defibrillation efficacy of a dual lead system with a 12-cm long defibrillation anode placed in the left subclavian vein. The data of 38 consecutive patients were retrospectively analyzed. The implantation of an active can system was attempted in 20 patients (group 1), and of the dual lead system in 18 patients (group 2). Both groups had comparable demographic data, cardiac disease, ventricular function, or clinical arrhythmia. The criterion for successful implantation was a DFT of > 24 J. This criterion was met in all 18 patients of group 2, The active can system could not be inserted in 3 of the 20 group 1 patients because of a DFT > 24 J. In these patients, the implantation of one (n = 2) or two (n = 1) additional transvenous leads was necessary to achieve a DFT ≤ 24). The DFTs of the 17 successfully implanted group 1 patients were not significantly different from the 18 patients in group 2 (12.3 ± 5.7 f vs 10.8 ± 4.8 J). The defibrillation impedance was similar in both groups (50.1 ± 6.1 ± 48.9 ± 5.2 Ω). In group 1, both operation duration (66.8 ± 17 min vs 80.8 ± 11 min; P < 0.05) and fluoroscopy time (3.3 ± 2.1 min vs 5.7 ± 2.9 min; P < 0,05) were significantly shorter. Thus, the active can system allows reliable transvenous defibrillation and a marked reduction of operation duration and fluoroscopy time. The dual lead system, with an increased surface area defibrillation anode, seems to he a promising alternative for active can failures.     

Diaphragm Pacing with a Quadripolar Phrenic Nerve Electrode: An International Study

We sought to determine the international experience with the quadripolar diaphragm pacer system and to test two hypotheses: the incidence of pacer complications would be (1) increased among pediatric as compared to adult patients; and (2) highest among active pediatric patients with idiopathic congenital central hypoventilation syndrome (CCHS). Data were collected via a questionnaire coupled with the Atrotech Registry data for a total of 64 patients (35 children and 29 adults) from 14 countries. Thoracic implantation of electrodes and bilateral pacer use each occurred in 94% of all subjects. Tetraplegic (vs pediatric CCHS) patients were more typically paced 24 hours/day (P = 0.001). Pacing duration averaged 2.0 ± 1.0 years among children and 2.2 ± 1.1 years among adults. Infections occurred among 2.9% of surgical procedures, all in pediatric CCHS patients (vs pediatric tetraplegic patients, P = 0.01). The incidence of mechanical trauma was 3.8%, without significant differences among patient groups. The incidence of presumed electrode and receiver failure were 3.1% and 5.9%, respectively, with internal component failure greater among pediatric CCHS than pediatric tetraplegic patients (P < 0.01). Intermittent or absent function of 0–4 electrode combinations occurred among 19% of all patients, with increased frequency among pediatric CCHS than pediatric tetraplegic patients (P < 0.03). Complication- free successful pacing occurred in 60% of pediatric and 52% of adult patients. In all, 94 % of the pediatric and 86% of the adult patients paced successfully after the necessary intervention. Although pacer complications were not increased among pediatric as compared to adult patients, the incidence of complications was highest among the active pediatric patients with CCHS. Longitudinal study of these patients will provide invaluable information for modification and improvement of the quadripolar system.     

The Influence of Sodium Channel Blockade on the Defibrillation Energy Requirements of Diphasic Versus Monophasic Shocks

The sodium channel-blocking actions of some Class I antiarrhythmic agents can increase the defibrillation energy requirements (DER) of monophasic shock waveforms. The influence of sodium channel blockade on biphasic shocks is less certain. The purpose of this study was to compare, in a randomized, placebo controlled study, the influence of lidocaine on the DER of biphasic and monophasic shock waveforms in a canine model of transvenous internal defibrillation. The DER was determined by the iterative increment-decrement protocol. Monophasic and biphasic shock DERs were tested at baseline and during lidocaine infusion (group A) or saline control (group B). Group A biphasic shock DERs increased significantly from a baseline of 12.1 ± 3.6 J to 19.1 ± 9.3 J when compared to group B (P = 0.005). In group A, the mean DER during lidocaine was significantly higher with monophasic shocks than biphasic shocks (29.6 ± 11.8 f vs 19.1 ± 9.3), respectively: P < 0.003), but the magnitude of change in biphasic versus monophasic shock DERs was not significantly different (F = 1.78; p = 0.193). There was a linear relationship between the baseline DER and the DER during lidocaine (r²= 0.63, P < 0.0001). Sodium channel blockade with lidocaine increases the DER of both monophasic and biphasic shocks. However, the DER of biphasic shocks during lidocaine are significantly lower than monophasic shock DERs, a finding that can be explained by the linear relationship between the baseline DER and the DER during lidocaine. These results may have favorable implications for the use of Class I antiarrhythmics with biphasic shock defibrillators.     

Clinical Experience with a Dual-Chamber Implantable Cardioverter Defibrillator to Treat Atrial Tachyarrhythmias

INTRODUCTION: This study evaluated the safety and efficacy of a new dual-chamber implantable cardioverter defibrillator (ICD) to detect and treat atrial tachyarrhythmias in patients with drug-refractory atrial fibrillation (AF) and no indication for a ventricular ICD. METHODS AND RESULTS: A dual-chamber ICD (Medtronic 7250 Jewel AF) was implanted in 144 of 146 patients. The device discriminates atrial tachycardia from AF based on cycle length and regularity, and uses atrial overdrive pacing as well as shocks to terminate tachyarrhythmia episodes. Patients were followed for an average of 12.6+/-6.2 months. Use of antiarrhythmic drugs was 63% at baseline and did not change over time. Kaplan-Meier estimates of 12-month complication-free survival, device therapy survival, and patient survival were 85%, 91%, and 98%, respectively. Positive predictive accuracy of spontaneous atrial tachyarrhythmia detection was 99%, while atrial overdrive pacing and shocks terminated 40% and 87% of treated episodes, respectively. Median duration of successfully treated episodes was 8.9 minutes versus 144 minutes for the therapy failures. There was no reduction in the use of patient-activated shock therapy over time; at the 12-month follow-up evaluation, 94% of patients were in sinus rhythm. Ventricular tachyarrhythmias (67 episodes) were detected and appropriately treated in 7.6% of patients. CONCLUSION: This dual-chamber ICD appears to be safe and well tolerated in patients with drug-refractory symptomatic atrial tachyarrhythmias. The device, used in combination with drugs, effectively treats atrial tachyarrhythmias with pacing and/or shock therapies and decreases the median episode duration. In addition, the device protects from ventricular tachyarrhythmias in patients with AF and structural heart disease.     

Implantable Cardioverter Defibrillator Therapy for Primary Prevention of Sudden Cardiac Death after Myocardial Infarction:

Study Objective: To estimate the proportion of patients eligible for implantable cardioverter defibrillator (ICD) therapy for the primary prevention of sudden cardiac death after a myocardial infarction (MI), according to the current guidelines.
Methods: Eligibility was assessed retrospectively at 6 weeks in 513 post-MI survivors (age 66 ± 13 years, left ventricular ejection fraction 48.2 ± 17%) on the basis of an electrocardiogram and an echocardiogram.
Results: LVEF was ≤ 40% in 37% and ≤ 35% in 30%, and QRS duration was <120 ms in 89% and ≥120 ms in 11% of patients. The proportion of post-MI patients meeting the criteria set by guidelines were 37% for 2006 American College of Cardiology/American Heart Association/European Society of Cardiology (ACC/AHA/ESC) 26.5% for 2008 ACC/AHA/Canadian Heart Rhythm Society 16.3% for 2005 US Centers for Medicare and Medicaid Services (CMS), and 5.8% for the 2006 United Kingdom (UK) National Institute of Clinical Excellence (NICE). According to 2005 CMS and 2006 UK-NICE guidelines, Holter monitoring was required in 7% and 18%, respectively. For the United States (700,000 MI in 2006), the 2006 ACC/AHA/ESC guidelines equate to 216,783 ICD implantations/year. For UK (60,499 MI in 2006), the 2006 NICE guidelines equate to 2,941 ICD implantations, 10,488 Holter studies, and 1,065 VT induction tests/year.
Conclusions: Current ICD therapy guidelines for primary prevention of SCD post-MI demand a substantial increase in service provision worldwide.     

Malignancy: Meningeal Myeloma: A Case Report and Review of Literature

Purpose: Report and review of an uncommon complication of multiple myeloma. Methods: We report a case of leptomeningeal myeloma and using Medline, review previously reported cases. Results: We found 35 previously reported cases of meningeal myeloma. Of the 36 cases, including the present case, the male to female ratio was 2:1 with a median age of 58 years (range, 31 to 83 years). Forty five percent of the patients had circulating plasma cells and 90.9% had plasma cells in the cerebrospinal fluid. All but 4 cases were diagnosed antemortem. Thirty patients had a pre-existing diagnosis of multiple myeloma, while leptomeningeal disease was the presenting feature in six. Management included a combination of intrathecal chemotherapy and radiation therapy, radiation therapy alone or intrathecal chemotherapy alone in 14, 3, and 3 patients respectively. Thirteen patients also received systemic chemotherapy in addition to some form of local therapy. The median survival for the entire group was 8 weeks (range 4 days to 18 months). Even those who initially responded to local therapy relapsed in the central nervous system (CNS) or succumbed to systemic disease. Five of six patients in whom CNS disease was the presenting feature survived 4 weeks or less. Conclusions: Leptomeningeal involvement is a rare and fatal complication of multiple myeloma with a short survival despite aggressive intrathecal and systemic chemotherapy and radiation therapy.     

Low‐Dose Heparin for Elective Percutaneous Coronary Intervention

Objectives

We evaluated the safety and efficacy of low‐dose heparin (40 IU/kg) for elective percutaneous coronary intervention (PCI).

Background

Current guidelines recommend a 70–100 IU/kg bolus of heparin for elective PCI, but this dose may be associated with increased bleeding risk. Low‐dose heparin may have an advantage in this regard, but has not been well studied.

Methods

From January 2008 to October 2012, 300 patients underwent elective transfemoral PCI and were treated with an initial bolus of 40 IU/kg of heparin at the UCLA Medical Center. Dual antiplatelet therapy with clopidogrel and aspirin was administered prior to or just after diagnostic coronary angiography. The primary end‐point was the composite of cardiac death, myocardial infarction, urgent target vessel revascularization for ischemia, or major bleeding within 30 days after PCI.

Results

The mean activating clotting time was 233 ± 28 seconds. The primary end‐point occurred in 2.3%. The cardiac death rate was 0.3% but was not related to the PCI. The myocardial infarction rate was 1.3%. Urgent target vessel revascularization occurred in 1 patient (0.3%). The major bleeding rate was 0.3%. No stent thrombosis occurred.

Conclusion

Using a lower dose of heparin with dual antiplatelet therapy is safe and is associated with a low bleeding risk after transfemoral PCI while providing suppression of ischemic events. This may also represent a cost savings compared with other antithrombotic strategies. A randomized clinical trial comparing low‐dose heparin with bivalirudin in patients is required to determine the optimal anticoagulation strategy. (J Interven Cardiol 2014;27:58–62)

     

Application of the “Hybrid Approach” to Chronic Total Occlusion Interventions: A Detailed Procedural Analysis

Objective

To assess the outcomes of the “hybrid” approach to chronic total occlusion (CTO) percutaneous coronary interventions (PCIs).

Background

The “hybrid approach” to CTO PCI advocates appropriate and early change of crossing strategy to maximize success, safety, and efficiency.

Methods

We prospectively recorded and analyzed detailed step‐by‐step procedural data in 73 consecutive CTO PCI cases performed by a single operator between July 2011 and August 2012.

Results

Technical success was achieved in 66 of 73 cases (90.4%). Mean patient age was 65 ± 7 years, and 30% had prior coronary artery bypass surgery. Dual injection was used in 78%. The primary approach was retrograde in 9 cases (12.5%) and antegrade in 64 cases (87.5%), of whom 25 cases (39.1%) underwent retrograde attempt after failed antegrade approach. The initial crossing approach was successful in 40 cases (54.8%), but 32 cases (44%) required 3.6 ± 1.4 approach changes (range 2–7). Antegrade wire escalation, antegrade dissection/reentry, and retrograde crossing were utilized in 97.2%, 46.6%, and 46.6% of cases, respectively. Among successful cases, the final CTO crossing technique was antegrade wire escalation in 50.0%, antegrade dissection/reentry in 24.2%, and retrograde in 25.8%. The mean procedure time, fluoroscopy time, and air kerma radiation exposure until CTO crossing or stopping the procedure were 66 ± 55 minutes, 25 ± 23 minutes, and 2.3 ± 1.9 Gray, respectively. Three patients (4.1%) had a major complication.

Conclusion

In the “hybrid approach” to CTO PCI, changes in crossing strategy were needed in approximately half the cases, resulting in high success and low complication rates. (J Interven Cardiol 2014;27:36–43)