High-energy ion beams are successfully used in cancer therapy and precisely deliver high doses of ionizing radiation to small deep-seated target volumes. A similar noninvasive treatment modality for cardiac arrhythmias was tested here. This study used high-energy carbon ions for ablation of cardiac tissue in pigs. Doses of 25, 40, and 55 Gy were applied in forced-breath-hold to the atrioventricular junction, left atrial pulmonary vein junction, and freewall left ventricle of intact animals. Procedural success was tracked by (1.) in-beam positron-emission tomography (PET) imaging; (2.) intracardiac voltage mapping with visible lesion on ultrasound; (3.) lesion outcomes in pathohistolgy. High doses (40–55 Gy) caused slowing and interruption of cardiac impulse propagation. Target fibrosis was the main mediator of the ablation effect. In irradiated tissue, apoptosis was present after 3, but not 6 months. Our study shows feasibility to use high-energy ion beams for creation of cardiac lesions that chronically interrupt cardiac conduction.

Our findings suggest that psychiatry has an image problem that is widespread, reflecting community perceptions and the specialist interests of medical students on recruitment. If psychiatry is to improve its 'attractiveness' as a career option, identified image problems need to be corrected and medical student selection processes re-considered.

The attitudes of medical students can perhaps be modified and recruitment into psychiatry enhanced by presenting the reality of psychiatry today - namely the wide range of available therapeutic processes, the predominantly positive outcomes, the interesting and intellectually challenging nature of the subject and its nurturing and accommodating work environment.

Background-Formation of microemboli during catheter ablation has been suggested as a cause for asymptomatic cerebral emboli. However, it is unknown which part of the process and ablation setting/strategy is most strongly related to this occurrence. Methods and Results-A total of 27 pigs were used. Catheter/sheath manipulations in left atrium were performed in 25 of 27 pigs outfitted with microemboli monitoring systems. Ablations using open-irrigated radiofrequency catheters were performed in 18 of 25 pigs. Two of 27 pigs did not undergo left atrial procedures and were injected with microembolic materials in the carotid artery to serve as positive controls. In total, 334 sheath/catheter manipulations (transseptal puncture, sheath flushing, catheter insertion, pulmonary vein venography, and sheath exchange) and 333 radiofrequency applications (power setting, 30/50 W; point-by-point/drag ablations) were analyzed. High microbubble volume in the extracorporeal circulation loop and a high number of microembolic signals in carotid artery were observed during sheath/ catheter manipulations especially in saline/contrast injections at fast speed and ablations with steam pop. Fast sheath flushing produced significantly higher microbubble volume than slow sheath flushing (median, 12 200 versus 121 nL; P<0.0001). A total of 44 of 126 (35%) blood filters in the circulation loop showed microparticles (thrombus/coagulum and tissue). Most of them were seen after radiofrequency application especially in 50-W ablations, drag ablations, and steam pop. Brain magnetic resonance imaging showed positive-embolic lesions in control pigs. Conclusions-Formation of microbubbles was the greatest during fast saline/contrast injections and steam pops, whereas high-power radiofrequency applications, drag ablations, and steam pops produced most of the microparticles.(Circ Arrhythm Electrophysiol. 2016;9:e003226.

Single-fraction doses as low as 25 Gy caused a lesion with interruption of cardiac impulse propagation using this respective target volume. With doses of ≤55 Gy, maximal point-doses to coronary arteries could be kept <7Gy, but target conformity of lesions was not fully achieved using this approach.

Variance in tissue thermodynamics during cryothermal ablation depends on the distance from balloon and peri-balloon blood flow leaks. This information may be useful for successful PVI without severe complications.

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Background - Proton beam therapy offers radiophysical properties that are appealing for noninvasive arrhythmia elimination. This study was conducted to use scanned proton beams for ablation of cardiac tissue, investigate electrophysiologic outcomes, and characterize the process of lesion formation in a porcine model using particle therapy. Methods - Twenty-five animals received scanned proton beam irradiation. ECG-gated CT scans were acquired at end-expiration breath hold. Structures (atrioventricular junction [AVJ] or left ventricular myocardium [LV]) and organs at risk were contoured. Doses of 30, 40, and 55Gy were delivered during expiration to the AVJ (AVJ; n=5) and LV myocardium (LV; n=20) of intact animals. Results - In this study, procedural success was tracked by pacemaker interrogation in the AVJ group, time-course magnetic resonance imaging (MR) in the LV group, and correlation of lesion outcomes displayed in gross and microscopic pathology. Protein extraction (active caspase-3) was performed to investigate tissue apoptosis. Doses of 40 and 55Gy caused slowing and interruption of cardiac impulse propagation at the AVJ. In 40 LV irradiated targets, all lesions were identified on MR after twelve weeks, being consistent with outcomes from gross pathology. In the majority of cases, lesion size plateaued between 12 and 16 weeks. Active caspase-3 was seen in lesions 12 and 16 weeks after irradiation, but not after 20 weeks. Conclusions - Scanned proton beams can be used as a tool for catheter-free ablation, and time-course of tissue apoptosis was consistent with lesion maturation.