Microwave, Irrigated, Pulsed, or Conventional Radiofrequency Energy Source: Which Energy Source for Which Catheter Ablation?

ERDOGAN, A., et al .: Microwave, Irrigated, Pulsed, or Conventional Radiofrequency Energy Source: Which Energy Source for Which Catheter Ablation? The aim of the study was to compare the diameter of endomyocardial lesions induced with the delivery of microwave, cooled, or pulsed energy versus conventional RF energy. In vitro tests were performed in fresh endomyocardial preparations of pig hearts in a 10-L bath of NaCl 0.9% solution at 37°C and constant 1.5 L/min flow. Ablation 7 Fr catheters with 4-mm tip electrodes were used, except for the delivery of microwave energy. Energy delivery time was set to 60 s/50 W in all experiments. Cooled energy delivery was performed with a closed irrigation catheter. Pulsed energy delivery was performed using a special controller with a duty-cycle of 5 ms. Microwave energy was delivered with a 2.5-GHz generator and 10-mm antenna. Electrode temperature and impedance were measured simultaneously. After ablation, lesion length, width, and depth were measured with microcalipers, and volume calculated by a formula for ellipsoid bodies. Each energy delivery mode was tested in ten experiments. The deepest lesions were created with cooled energy delivery, and the largest volume by microwave energy delivery. Pulsed RF produced significantly deeper lesions than conventional RF energy delivery. Cooled or pulsed RF energy delivery created deeper transmural lesions than conventional RF. To create linear lesions at anatomically complex sites (isthmus), microwave energy seemed superior by rapidly creating deep and long lesions. (PACE 2003; 26:[Pt. II]:504–506)     

Effect of Biphasic Waveform Pulse on Endocardial Defibrillation Efficacy in Humans

Several clinical studies have proved increased defibrillation efficacy for implantable cardioverter defibrillators with biphasic pulse waveforms compared to monophasic pulse waveforms. This difference in defibrillation efficacy depends on the type of defibrillation lead system used. The influence of biphasic defibrillation pulse waveforms on the defibrillation efficacy of purely endocardial defibrillation lead systems has not yet been sufficiently examined, we, therefore studied 30 consecutive patients with drug refractory ventricular tachyarrhythmias during the implantation of a cardioverter defibrillator. After implanting an endocardial "integrated" sensing/defibrillation lead we performed a prospective randomized comparison of the defibrillation efficacy of monophasic and biphasic defibrillation waveform pulses. For endocardial defibrillation with the biphasic waveform the mean defibrillation threshold was 12.5 ± 4.9 joules and for the monophasic waveform 22.2 ± 5.6 joules (P < 0.0001). There was a decrease in the required defibrillation energy of biphasic defibrillation in 29/30 patients. Thus considering purely endocardial defibrillation a statistically significant and clinically relevant increase in defibrillation efficacy can be demonstrated for biphasic defibrillation waveform pulses.     

Effects of Exposure to GSM Mobile Phone Cortisol,Alpha-Amylase,and Base Station Signals on Salivary Immunoglobulin A

Objective The present study aimed to test whether exposure to radiofrequency electromagnetic fields （RF-EMF） emitted by mobile phone base stations may have effects on salivary alpha-amylase, immunoglobulin A （IgA）, and cortisol levels. Methods Fifty seven participants were randomly allocated to one of three different experimental scenarios （22 participants to scenario 1, 26 to scenario 2, and 9 to scenario 3）. Each participant went through five 50-minute exposure sessions. The main RF-EMF source was a GSM-900-MHz antenna located at the outer wall of the building. In scenarios 1 and 2, the first, third, and fifth sessions were ＂low＂ （median power flux density 5.2 μW/m^2） exposure. The second session was ＂high＂ （2126.8 μW/m^2）, and the fourth session was ＂medium＂ （153.6 μW/m^2） in scenario 1, and vice versa in scenario 2. Scenario 3 had four ＂low＂ exposure conditions, followed by a ＂high＂ exposure condition. Biomedical parameters were collected by saliva samples three times a session. Exposure levels were created by shielding curtains. Results In scenario 3 from session 4 to session 5 （from ＂low＂ to ＂high＂ exposure）, an increase of cortisol was detected, while in scenarios 1 and 2, a higher concentration of alpha-amylase related to the baseline was identified as compared to that in scenario 3. IgA concentration was not significantly related to the exposure. Conclusions RF-EMF in considerably lower field densities than ICNIRP-gnidelines may influence certain psychobiological stress markers.     

Safety and Efficacy of Angiographic Guided Elective Palmaz-Schatz Stent Implantation Without Coumadin: Comparison of Stent Implantation and Angioplasty

This study was designed to evaluate the safety and efficacy of routine high-pressure Palmaz-Schatz coronary stenting in patients with symptomatic coronary heart disease with only angiographic guidance without coumadin for poststenting treatment. Intracoronary stenting reduces restenosis rate after coronary angioplasty. High pressure stent deployment with intravascular ultrasound guidance reduces the incidence of stent thrombosis, despite reduction of anticoagulation. However, the feasibility of routine stent implantation with only angiographic guidance and without coumadin for poststenting treatment has not yet been determined. Patients undergoing coronary angioplasty for symptomatic coronary heart disease received stent implantation for abrupt or threatening vessel occlusion, vessel dissection without compromised antegrade blood flow (but at high risk for subacute occlusion and early restenosis), unsatisfactory angioplasty result with > 30% residual stenosis, and elective stent implantation in de novo lesions, restenotic lesions, and lesions in bypass grafts. Quantitative coronary analysis was performed before the procedure, immediately after, and at follow-up 6 ± 1 (SD) months later. This patient group was matched for clinical and angiographic characteristics with those patients who underwent balloon angioplasty during the same period. Patients who underwent coronary stenting had larger net gain (1.95 ± 1.0 vs 1.42 ± 0.9; P < 0.001) resulting in a larger minimal luminal diameter (2.48 ± 1.19 vs 1.78 ± 1.01; P < 0.001) at follow-up as compared with balloon angioplasty. Restenosis, defined as > 50% diameter stenosis at follow-up, occurred in 35.0% in the PTCA group and in 16.1% in the stent group (P < 0.001). Subacute stent thrombosis occured in one patient (0.8%) due to angiographically evident suboptimal stent expansion. Routine coronary high pressure Palmaz-Schatz stenting with angiographie guidance without coumadin for poststenting treatment represents a safe and effective option in patients with symptomatic coronary heart disease without increasing the incidence of (sub)acute stent thrombosis.