Sputter-Deposited TiN Electrode Coatings for Superior Sensing and Pacing Performance

SCHALDACH, M., ET AL.: Sputter-Deposited TiN Electrode Coatings for Superior Sensing and Pacing Performance. The sensing and pacing performance of pacemaker electrodes is characterized by the electrochemical properties of the electrode/tissue interface affecting tissue reactions and the kinetics of the ionic exchange. The usually smooth metallic electrode surface results in a high pass filter characteristic. To better match the electrode's filter characteristic to the spectral content of the depolarization signal, various combinations of electrode shape, material and surface structure have been researched. The electrode with sputter-deposited TiN coating presented in this report has been designed to meet the demand for low acute as well as chronic thresholds and superior sensing performance not only with respect to spontaneous activity but also regarding the detection of the evoked response. The clinical results obtained with this electrode prove the excellent pacing and sensing properties resulting from minimized polarization losses and optimized filtering of the signal to be detected, respectively. The acute and chronic clinical advantages over previous concepts are attributed mainly to the biocompatibility of the material used and the microcrystalline surface structure achieved by the coating process. The design concept of the new electrode is presented together with the clinical results obtained. While the advancements in microelectronics and battery technology have certainly formed the basis for the development of pulse generators featuring an ever increasing versatility of functions at the same or even smaller pacemaker dimensions, from a point of view of pacing system performance the development of improved electrode concepts as the one presented must be regarded as equally indispensable.     

How Reliable is Atrial Sensing in Single-Lead VDD Pacing: Comparison of Three Systems

This study evaluated the reliability of atrial sensing, expressed as AV synchronous stimulation, in three VDD systems with the atrial sensitivity (AS) programmed to a conventional value with a 2:1 safety margin compared to most-sensitive values. We studied 34 sex- and age-matched patients with 3 VDD systems: 14 with Unity 292–07, 10 with Saphir 600, and 10 with Thera VDD (5 model 8948 and 5 model 8968i). Two 24-hour Hollers were performed on consecutive days. The AS was programmed in a randomized order to its most-sensitive value or to a 2:1 safety margin. All other parameters were programmed identically. The patients underwent a myopotential oversensing test and a daily life activity protocol. A beat-to-beat analysis of the Holters was performed to determine AV synchrony. For the entire group AV synchrony with conventional AS was 98.63%± 2.57%, compared to 99.80%± 0.43% with most-sensitive values (p = 0.002). There was no difference between the three systems with conventional AS. With the most-sensitive AS, AV synchrony was: Unity 99.99%± 0.03%, Saphir 99.42%± 0.60% (P = 0.002), Thera 99.81 %± 0.35% (ns). In the Saphir system with an atrial blanking period of 150 ms, ventricular far-field sensing could be demonstrated in 5 of 10 patients. This reduced the percentage of AV synchrony due to an unwanted mode-switch to a nontracking mode. Myopotential oversensing was not detected in any patient. Conclusion: The VDD systems tested under identical conditions showed reliable P wave sensing at the most-sensitive atrial sensing setting without myopotential oversensing. Ventricular far-field sensing reduced AV synchrony and must be avoided by appropriate refractory periods.     

A Prospective Randomized Evaluation of VV Delay Optimization in CRT-D Recipients: Echocardiographic Observations from the RHYTHM II ICD Study

Background: All current cardiac resynchronization therapy (CRT) devices allow the programming of the atrioventricular (AV/PV) delays and the sequential stimulation of the ventricles via the inter ventricular (VV) delay.
Aim: This post hoc analysis of the RHYTHM II study was conducted to compare the reverse remodeling associated with VV delay optimization in patients randomly assigned to simultaneous (SIM) biventricular stimulation versus patients assigned to optimized VV delay programming (OPT) (1:3 randomization scheme).
Methods: The analysis included 14 patients assigned to the SIM group and 34 patients to the OPT group who completed the 6-month follow-up period with paired echocardiographic recordings.
Results: In both study groups, changes consistent with left ventricular (LV) remodeling were observed between baseline and 6 months, with significant improvements in LV function and decrease in LV dimensions. In the OPT group, there was also a decrease in left atrial diameter and mitral valve closure to opening time. At 6 months, the overall proportion of echocardiographic responders (≥10% decrease in LV end-systolic volume or ≥5% absolute increase in LV ejection fraction) was similar in both groups. The optimal AV/VV delays, evaluated by maximization of LV outflow tract velocity time integral, changed over time.
Conclusions: Ventriculo-ventricular delay optimization was associated with better immediate hemodynamic function than simultaneous biventricular stimulation, though did not promote additional reverse remodeling at 6 months and did not increase the proportion of echocardiographic responders to CRT. Optimization of both the AV and VV intervals was patient-specific and optimal values changed over time.     

Echocardiographic Imaging of Coronary Sinus Diverticula and Middle Cardiac Veins in Patients with Preexcitation Syndrome: Impact on Radiofrequency Catheter Ablation of Posteroseptal Accessory Pathways

OMRAN, H., ^{et al}.: Echocardiographic Imaging of Coronary Sinus Diverticula and Middle Cardiac Veins in Patients with Preexcitation Syndrome: Impact on Radiofrequency Catheter Ablation of Posteroseptal Accessory Pathways . To determine the value of echocardiography for identifying coronary sinus (CS) diverticula and middle cardiac veins (MCVs) in patients with posteroseptal accessory pathways (PAPs), transthoracic (TTE) and transesophageal echocardiography (TEE) were performed in 18 consecutive patients with PAP and in 15 control subjects with left lateral accessory pathway before CS angiography. The size, shape, and location of CS diverticula and MCV were described and compared to angiography. TEE and angiography were concordant for the identification of diverticula (n = 5) and agreed for depicting MCV in 22 of the 27 cases. TTE revealed 4 of 5 diverticula and identified 4 of 27 MCV (P < 0.001). Fourteen MCV but no diverticula were found in the control subjects. There was no significant difference between transesophageal and angiographic measurements for the width (23.5 ± 4.9 vs 26.8 ± 6.6 mm) and height (13.5 ± 3.8 vs 15.7 ± 3.4 mm) of the diverticula, and the width (3.5 ± 0.7 vs 3.7 ± 0.6 mm) of MCV. TEE underestimated the length of the MCV (12.0 ± 1.8 vs 27.2 ± 6.0, P < 0.001). Delivery of radiofrequency energy within the neck of a diverticulum or within an MCV was successful in 5 of 5, and 6 of 13 cases in patients with PAPs, respectively. In conclusion, echocardiography was as reliable as angiography for detecting and describing CS diverticula and MCV in patients with preexcitation syndrome. Echocardiography is recommended prior to electrophysiological study because it may simplify radiofrequency catheter ablation.     

Pain Sensation during Intradermal Injections of Three Different Botulinum Toxin Preparations in Different Doses and Dilutions

BACKGROUND: Pain sensation associated with injections of botulinum neurotoxin (BoNT) is commonly reported. To date differences in pain sensation between the commercially available products containing BoNT have not been quantified. OBJECTIVES: The pain sensations during injection of Dysport, Botox, Neurobloc, and pure saline (control) were compared. In addition, the nociceptive effect of different volumes used for the dilution of the same BoNT dose was investigated. METHODS: In a prospective, double-blind, controlled trial, 10 healthy subjects were injected intradermally with Dysport (12 U), Botox (3 and 4 U), Neurobloc (150 and 300 U) reconstituted in 0.9% saline, and pure saline. Pain sensation was quantified during injections. RESULTS: Neurobloc injections caused significantly more injection pain than Botox, Dysport, and saline. No significant differences between Dysport, Botox, and saline were found, although there was a trend toward less pain with pure saline injections. Higher pain levels with higher volumes could not be demonstrated significantly. CONCLUSION: Our data demonstrate that BoNT type B injections are associated with substantial pain. There is a considerable difference between the commercially available BoNT type B compared to the two BoNT type A preparations. Therefore, considering mitigation of injection pain seems necessary when using BoNT type B.     

Defibrillator Implantation in a Patient with a Persistent Left Superior Vena Cava

The implantation of a transvenous cardioverter defibrillator (PCD 7217B) was performed in a patient with a persistent left superior vena cava. The defibrillation electrodes were positioned in the right ventricle and the superior vena cava via the right subclavian vein. A subcutaneous patch had to be implanted at the left lateral chest wall to achieve sufficient defibrillation thresholds. Three weeks later the system had to be removed because of a generator pocket infection. During the second implantation we placed one electrode in the persistent left superior vena cava perpendicular to the electrode in the right ventricle. Using this configuration transvenous defibrillation was possible without an additional subcutaneous patch.