Cardiology Telemetry Annotated Bibliography

Compendium to Research in Cardiology and Telemetry

Cotiga, D., et al. (2007). Acute Conversion of Persistent Atrial Fibrillation During Dofetilide Initiation. Pacing & Clinical Electrophysiology, 30(12), 1527-1530. doi:10.1111/j.1540-8159.2007.00902.x.

The researchers look at the role of Dofetilide (D) as "a highly selective blocker of the rapid component of the delayed rectifier potassium current;" approved for the treatment of atrial fibrillation (AF). The study is a replication of clinical trials that concluded in a satisfactory safety/efficacy profile in patients with left ventricle (LV) dysfunction or heart failure. The participants to the investigation all received at least 6 dosing intervals D. while admitted in the Telemetry unit. Seventy seven percent (77%) of the patients converted to sinus rhythm (SR) after the first 2.2 ± 1.2 doses. Findings to the investigation revealed that: 1) D. had an unusually high pharmacological conversion rate; 2) demonstrated response with incremental dosage; and 3) correlated with a high tolerance which determined a high degree of safety in the study's relatively healthy adult cohort with persistent AF. LA and AF also contributed to the predictability of the duration of the D. dose. The hypothesis proved correct: that acute pharmacological conversion rate of D. is (< or +) than previously assumed if administered to an equivalent population of patients.

Lewalter, T., et al. (2007). Morphology-Enhanced Atrial Event Classification Improves Sensing in Pacemakers. Pacing & Clinical Electrophysiology, 30(12), 1455-1463. doi:10.1111/j.1540-8159.2007.00891.x.

An assessment of morphology-enhanced atrial event classification (MORPH) and potential for improvement of atrial-based pacing (ABP), the study looks at the technology's reliability of atrial arrhythmia diagnostics in heart rhythm devices in detection and discrimination of atrial signals. Methodological application to the study included observation of ambulatory atrial electrograms recorded continuously through monitoring of the telemetry of digital pacemakers. Data analysis was inferred in the dual phase collection of the data: 1) individual morphology parameters that discriminated P-waves from FFRWs in every patient (learning phase); and 2) MORPH algorithm against traditional methods (classification phase). Results to the investigation conclude that in 44 out of 48 patients the data was suitable for analysis, with average P. And FFRW amplitudes at 1.96 mV versus 0.61 mV (P < 0.001). Recommendations drawn from the study attribute improved atrial signal discrimination and morphology analysis of atrial electrograms in high atrial sensitivity settings may increase reliability of atrial arrhythmia diagnostics in heart rhythm devices.

Crossley, G., et al. (2009). Atrial Fibrillation Therapy in Patients with a CRT Defibrillator with Wireless Telemetry. Pacing & Clinical Electrophysiology, 32(1), 13-23. doi:10.1111/j.1540-8159.2009.02171.x.

An international, multi-site study evaluates the efficacy of atrial shock therapy in patients with a cardiac resynchronization therapy defibrillator (CRT-D) to determine safety of new CRT-D, and its effectiveness. The study employed the Medtronic wireless telemetry system (Conexus; Medtronic Inc., Minneapolis, MN, USA), and looks at the effectiveness of a new wireless telemetry system on complications to atrial fibrillation (AF); a major cause of morbidity and mortality in telemetry care; especially in patients with congestive heart failure. Outcomes to the study include a (98.2%) success rate in patients of 168/171, where 138 were induced and 22 spontaneous. Successful cardioversion occurred in 137/138 of the induced-AF episodes (86.1% with 12 joule (J), 13.1% with 24 J, and 0.7% with 35 J). Conclusive to the study is an atrial shock efficacy of (98.2%) in those patients who met standard CRT-D indications. The wireless telemetry system had no reported unanticipated adverse device effects.

Crossley, G. et al. (2007). Automated Left Ventricular Capture Management. Pacing & Clinical Electrophysiology, 30(10), 1190-1200. doi:10.1111/j.1540-8159.2007.00840.x.

The investigation demonstrates that the Cardiac resynchronization therapy (CRT) based LVCM algorithm therapy is safe, accurate, and highly reliable method of reaching both ventricles. LVCM worked with different types of leads and different lead locations. According to the research, the stimulation thresholds of left ventricular (LV) leads tend to be less reliable than conventional leads. An evaluation of a novel algorithm for the automatic measurement of the stimulation threshold of LV leads in cardiac resynchronization systems. Sample to the study enrolled 134 out-patients from 18 centers who had existing CRT-D systems with software capable of automatically executing LV threshold measurements. Measurements were downloaded into the random access memory (RAM) of the device. Reported outcomes to the study indicate that the algorithm measured the threshold successfully in 96% and 97% of patients after 1 and 3 months respectivel, with augmentation of the data derived from the Holter monitor analysis where a subset of the test subjects revealed accurate performance of the algorithm. The test supports the claim that the new CRT-D improved ability to maintain LV capture without sacrificing device longevity.

Vasamreddy, C et al. (2006). Symptomatic and Asymptomatic Atrial Fibrillation in Patients Undergoing Radiofrequency Catheter Ablation. Journal of Cardiovascular Electrophysiology, 17(2), 134-139. doi:10.1111/j.1540-8167.2006.00359.x.

Objectives to the investigation to "(i) evaluate the feasibility and results of monitoring patients prior to and following catheter ablation of AF with the mobile cardiac outpatient telemetry (MCOT) system and to (ii) correlate symptoms and the presence or absence of atrial fibrillation (AF)" were designed to demonstrate the potential utility of wireless monitoring systems in the follow-up of AF patients. Of a total of 12/19 consecutive patients with (63%) age 60 ( ± 6 years) with highly symptomatic drug refractory AF underwent catheter ablation, each was provided with a MCOT monitor (CardioNet, USA) for a total of 494 days (11,856 hours) of monitoring. Termination of the study concluded at the end of the study with 6/10 patients completing the test. In those subjects (70%) patients were free of symptomatic AF recurrences compared to (50%) asymptomatic AF recurrences. Some identified poor patient compliance with an intensive monitoring protocol as an important limitation.

Chow, E. et al. (2009). Toward an Implantable Wireless Cardiac Monitoring Platform Integrated with an FDA-Approved Cardiovascular Stent. Journal of Interventional Cardiology, 22(5), 479-487. doi:10.1111/j.1540-8183.2009.00483.x.

The researchers investigate the value of a miniaturized stent-based antenna system for use in wireless telemetry and power transfer for the implanted electronics. Reduced to an area of less than 1 mm2, with a thickness under 300 ?m, research studies implantation of a minimally invasive implantation procedure; allowing the delivery of the stent-based implant in nearly any major vessel of the body. Initial prototype with two stents "configured as a single dipole, a 2.4-GHz transmitter microchip and battery [that] validates transcutaneous transmission through ex-vivo and in vivo porcine" is described.

The stent-based antenna can be used in monitoring of blood pressure from a minimally invasive device inserted for tracking the pulmonary artery in diagnostic and early warning system for cardiac health. In cardiac diagnostics, the foremost challenge in using a like device is the wireless transfer of data and power from within the blood vessel to external devices; whilst maintaining unrestricted blood flow through the artery.