Elizabeth Ching

Remote monitoring of cardiovascular devices: a time and activity analysis

BACKGROUND Expanding indications for cardiovascular implantable electronic devices are accompanied by an increasing burden of device clinic follow-up. Remote monitoring (RM) may be less time-consuming compared to in-office follow-up; however, its effect on the device clinic workflow has not been clarified. OBJECTIVE To determine the impact of RM on device clinic workflow. METHODS Detailed workflow data were prospectively collected over a 2-week period in a busy device clinic. RESULTS Five hundred remote transmissions were received from 434 patients between March 1 and March 16, 2011--346 implantable cardioverter-defibrillator, 84 pacemaker, and 70 implantable loop recorder transmissions--on 4 RM platforms (CareLink 56.4%, Merlin.net 21.4%, LATITUDE 17.8%, and Home Monitoring 4.4%). The mean time spent per transmission was 11.5 ± 7.7 minutes, which was less than in-person interrogations (27.7 ± 9.9 minutes; P <.01). Of 500 transmissions, 135 (27.0%) demonstrated clinically important findings; however, only 41 (8.2%) were forwarded for physician review. Of 500 transmissions, 138 (27.6%) were unscheduled, and these were more likely to contain a clinically important event (56 of 138 [40.6%] vs 79 of 362 [21.8%]; P = .0001). A total of 5.8% of the transmissions were duplicate. Transmissions that revealed clinically important findings took longer to process than those that did not (21.0 ± 7.4 minutes vs 10.1 ± 2.1 minutes; P <.05). A total of 49.2% of the scheduled remote transmissions were missed because of patient noncompliance. Telephone follow-up of patients (mean 21 patients/d) who missed scheduled remote transmissions took a mean of 55.1 (range 20-98) min/d. CONCLUSIONS Analysis of RM transmissions has significant implications for the device clinic workflow. Nonactionable transmissions are rapidly processed, allowing clinicians to focus on clinically important findings. However, poor patient compliance complicates the workflow efficiency of currently available systems.

NASPE Expert Consensus Document: Use of IV (Conscious) Sedation/Analgesia by Nonanesthesia Personnel in Patients Undergoing Arrhythmia Specific Diagnostic, Therapeutic, and Surgical Procedures

Use of IV (Conscious) Sedation/Analgesia by Nonanesthesia Personnel in Patients Undergoing Arrhythmia Specific Diagnostic, Therapeutic, and Surgical Procedures. This article is intended to inform practitioners, payers, and other interested parties of the opinion of the North American Society of Pacing and Electrophysiology (NASPE) concerning evolving areas of clinical practice or technologies or both, that are widely available or are new to the practice community. Expert, consensus documents are so designated because the evidence base and experience with the technology or clinical practice are not yet sufficiently well developed, or rigorously controlled trials are not yet available that would support a more definitive statement. This article has been endorsed by the American College of Cardiology, October 1997.

Effects of Extracorporeal Shock Wave Lithotripsy on Tiered Therapy Implantable Cardioverter Defibrillators

The effects of extracorporeal shock wave lithotripsy (ESWL) were tested on four advanced generation implantable cardioverter‐defibrillators (ICDs) in vitro and in vivo in two patients. During in vitro testing, advancement of nonsustained episode counters occurred in one device, and a set screw and power source cell loosened in another, which was connected to an external power source. No arrhythmias occurred during in vivo procedures, but programmed parameters were reset and elective replacement indicated after one procedure. ESWL can be performed safely in selected patients with ICDs, but testing should be performed afterwards to confirm satisfactory function and component continuity.

A comparison of 50-J versus 100-J shocks for direct-current cardioversion of atrial flutter

BACKGROUND Direct-current cardioversion remains the gold standard for restoration of sinus rhythm in patients with atrial flutter. Although an initial energy of 50 J is recommended, the optimal energy settings have not been evaluated in a large series of contemporary patients. METHODS We compared the outcome of cardioversion with 50 J versus 100 J in 330 consecutive patients with atrial flutter. Initial energy was based on attending physician preference. One hundred sixty patients received 50 J and 170 patients received 100 J. RESULTS Patients in both groups did not differ significantly in age, sex, weight, body mass index, duration of the arrhythmia, postoperative status, presence and type of structural heart disease, or use of antiarrhythmic drugs. Patients in the 100-J group had more first shock conversion (85% vs 70%; P =. 001), fewer total shocks (1.2 +/- 0.5 vs 1.4 +/- 0.7; P =.001), and less induction of atrial fibrillation (2% vs 11%; P =.002). There were no significant differences in overall restoration of sinus rhythm, cumulative energy delivered, anesthetic dose, and procedure room time. On multivariate analysis, delivery of 100 J was the strongest predictor of first shock success (odds ratio 2.6, 95% confidence interval 2.13 to 3.16; P <.001). CONCLUSION An initial energy of 100 J is more efficient for restoration of sinus rhythm in patients with atrial flutter.

Matching approved nondedicated hardware to obtain biventricular pacing and defibrillation: Feasibility and troubleshooting

KANAGARATNAM, L., et al.: Matching Approved “Nondedicated” Hardware to Obtain Biventricular Pacing and Defibrillation: Feasibility and Troubleshooting. Biventricular ICDs may offer increased benefit for patients with severe congestive heart failure and ventricular arrhythmia. Currently there are no approved dedicated biventricular ICDs available. Twenty‐one consecutive patients who had approved nondedicated hardware implanted for biventricular pacing and defibrillation were included in this study. All device therapies were evaluated using stored electrograms. During mean follow‐up at 13 ± 7 months, 8 (36%) patients had inappropriate shocks. Ventricular fibrillation therapy was delivered for slow ventricular tachycardia because of double counting in two patients. In one patient, AV nodal reentrant tachycardia below detection rate cut off triggered device therapy because of ventricular double counting. Sinus tachycardia or premature atrial contraction initiating AV conduction and ventricular double counting resulted in shocks in five patients. The number of shocks per patient ranged from 1 to 64. Two patients required transient disconnection of the LV lead and subsequent ICD generator replacement for premature battery depletion. Two patients required AV junction ablation and three needed slow pathway ablation. Two patients were treated by upgrading to a device that was capable of a higher atrial tracking rate. The patients with impaired AV conduction or constant ventricular pacing did not have inappropriate therapy for sinus tachycardia or supraventricular arrhythmia. Use of conventional nondedicated hardware for biventricular pacer/defibrillator is feasible but should be considered only in patients with poor AV node function or less likely to require antitachycardic therapy, to avoid ICD double counting of ventricular sensed events and consequent high incidence of inappropriate therapies.

Cost effectiveness of administration of intravenous anesthetics for direct-current cardioversion by nonanesthesiologists

Well-trained nonanesthesiologists can safely and effectively administer IV anesthetics for cardioversion. This practice results in considerable cost savings without compromising patient care.

Early Clinical Experience with a Minute Ventilation Sensor DDDR Pacemaker

The new DDDR pacemaker META DDDR utilizes a minute veritilation sensor based on transthoracic impedance measurements. The sensor determines the metabolic indicated interval, the atrioventricular (AV) delay and the postventricular atrial refractory period (PVARP). The baseline PVARP must be carefully selected to define nonphysiological tachycardias. If a Pwave falls within the PVARP the pacemaker will automatically switch to the VVIR mode. This behavior prevents tracking of paroxysmal atrial tachyarrhythmias (PAT). Twenty‐eight patients with sinus node dysfunction (n = 20), AV junction ablation (n = 5), complete or intermittent AV block (n = 3); who received a META DDDR pacemaker were studied. The mean age was 65 ± 13 years. Results: mode switching (reversion) to VVIR was observed in 57% of the patients. Forty‐two percent had episodes of mode switching to VVIR during a stress test four related to PAT, and seven to sinus tachycardia. Fifty percent had episodes of mode switching to VVIR during a 24‐hour Holter, four related to PAT, three to retrograde P wave sensing, and two to sinus tachycardia. At the last follow‐up, 20 of the 26 patients initially programmed to the DDDR mode remained in the DDDR mode, while five were reprogrammed to the DDD and one to the VVIR mode. Mode switching has a high sensitivity but a low specificity for PAT. It appears to be a useful approach to prevent rapid tracking of atrial tachyarrhythmias. Careful PVARP programming is critical to appropriate reversion behavior, but further modifications of the algorithm are needed to improve its performance.

Implantable cardioverter-defibrillator FDA safety advisories: Impact on patient mortality and morbidity

BACKGROUND A significant proportion of implantable cardioverter-defibrillators (ICDs) have been subject to Food and Drug Administration (FDA) advisories. The impact of device advisories on mortality or patient care is poorly understood. Although estimated risks of ICD generators under advisory are low, dependency on ICD therapies to prevent sudden death justifies the assessment of long-term mortality. OBJECTIVE To test the association of FDA advisory status with long-term mortality. METHODS The study was a retrospective, single-center review of clinical outcomes, including device malfunctions, in patients from implantation to either explant or death. Patients with ICDs first implanted at Cleveland Clinic between August 1996 and May 2004 who became subject to FDA advisories on ICD generators were identified. Mortality was determined by using the Social Security Death Index. RESULTS In 1644 consecutive patients receiving first ICD implants, 704 (43%) became subject to an FDA advisory, of which 172 (10.5%) were class I and 532 (32.3%) were class II. ICDs were explanted before advisory notifications in 14.0% of class I and 10.1% of class II advisories. Among ICDs under advisory, 28 (4.0%) advisory-related and 15 non-advisory- related malfunctions were documented. Over a median follow-up of 70 months, 814 patients died. Kaplan-Meier 5-year survival rate was 65.6% overall, and 64.2, 61.1, and 69.3% in patients with no, class I, and class II advisories, respectively (P = .17). CONCLUSIONS ICD advisories impacted 43% of the patients. Advisory-related malfunctions affected 4% within the combined advisory group. Based on a conservative management strategy, ICDs under advisory were not associated with increased mortality over a background of significant disease-related mortality.

Design‐Dependent Cross‐Talk in a Second Generation DDD Pacemaker

. A unique mechanism of “cross‐talk” has recently been described in the Gemini 4J5A DDD pacemaker in which cross‐inhibition of the ventricular output stimulus may occur in the early Gemini 415A models which were manufactured with dual anodal rings interconnected by a wire. The Gemini 415A units with dual anodal rings were implanted under investigational protocol in 53 patients from September 1982 to August 1984. To date, cross‐talk has been discovered in six patients during clinical follow‐up, manifesting as inappropriate ventricular inhibition. Syncope was documented in one patient. Non‐Cordis atrial and ventricular leads were present in all six patients and five patients had at least one chronic lead. Cross‐talk was neither evident nor provokable in Gemini 415A units which had compatible Cordis lead systems. Reduction of the atrial output and/or the ventricular sensitivity prevented cross‐inhibition in three patients. Cross‐talk persisted in three patients despite programming to the lowest atrial output and/or ventricular sensitivity parameters. Cross‐talk, spontaneous or provoked, has not occurred in 36 patients having currently designed 415A pulse generators manufactured with a single anodal ring in the ventricular connector channel. We conclude that: (1) this unique form of cross‐talk is “design‐dependent” and occurs only in Gemini 415As with dual interconnected anodal rings and cannot occur in 415As manufactured with a single anodal ring; (2) this form of cross‐talk has occurred only in 415As with non‐Cordis leads and appears to be a time dependent development; (3) reduction of the atrial output or use of pacing modes without atrial pacing or ventricular sensing can prevent cross‐talk; (4) patients with Gemini 415As having dual anodal rings, which can be identified radiographically. are at risk for this design‐dependent cross‐talk and merit close observation.