Current recovery therapies for life-threatening arrhythmias disregard the pathological electro-anatomical substrate and bottom their efficacy on the generalized electric discharge. fibrillation, stand for a economic and cultural burden in the overall population. The electro-anatomical substrate of the arrhythmias is seen as a conduction heterogeneities that facilitate macro and micro re-entrant circuits1. Electrical cardioversion, attempted either with implantable or exterior gadgets, is the initial choice option regarding to current suggestions2. However, electric cardioversion operates overlooking the characteristic top Avosentan (SPP301) manufacture features of re-entrant conduction pathways and its own efficiency rests on recording the whole center using a generalized electric discharge3. For example, implantable cardioverter defibrillator (ICD) shocks trigger intense discomfort, myocardium harm, and chest muscle tissue contractures, using a non-negligible threat of accidents and unbearable psychological discomfort4 often; moreover, unacceptable ICD-shocks are common5 regrettably. In this situation, efforts towards reducing ICDs electric entrainments need a deeper understanding of the occasions resulting in the starting point and advancement of arrhythmias. Light supplies the versatility necessary to develop and check customized excitement patterns with the capacity of effectively interrupting arrhythmias at lower energy. We exploit latest breakthroughs in optogenetics6,7,8 and imaging methods9,10 to build up a book optical platform with the capacity of concurrently mapping and managing the electric activity of entire hearts with sub-millisecond temporal resolution. An ultra-fast laser scanning system is used to design arbitrarily-chosen stimulation patterns across the whole heart. The platform is then used to characterize arrhythmias and to efficiently restore the cardiac sinus rhythm by intervening with customized stimulation patterns. Results A Avosentan (SPP301) manufacture wide-field macroscope (Fig. 1a) operating at 2,000 frames per second was developed and used to map the action potential propagation in Langendorffs horizontally-perfused mouse hearts loaded with a red-shifted voltage sensitive dye (di-4-ANBDQPQ)11. Sinus rhythm in perfused hearts was characterized by regular and rapid activation of the ventricles monitored by electrocardiographic (ECG) recordings (Fig. 1b, Figure S1, Table S1, Avosentan (SPP301) manufacture Video S1) and propagation maps (Fig. 1c). To optically control the cardiac electrical activity, we generated transgenic mice expressing the photo-sensitive ion channel, Channelrhodopsin 2 (ChR2)12 and exploited light-induced depolarization as one means for localized electrical discharges. We first compared the activation features of a point source stimulation, induced either with an electrode or with ChR2 photo-activation. Electrical and optical point stimulation evoked similar isochronal maps (Fig. 1d, Videos S2C3), suggesting that the ChR2 activation represents an effective alternative to the electrical stimulation. Notably, the use of the red-shifted voltage sensitive dye ensured that its excitation wavelength (640?nm) was unable to generate unwanted ChR2 activation (Fig. 1b, Table S1). Figure 1 Simultaneous all-optical map and control of cardiac conduction pathway. We then experimentally induced arrhythmias by rapid ventricular pacing during perfusion with a glucose- and oxygen-free solution, mimicking ischemic conditions13. This solution induced alterations of the electrical propagation in the form of partial atrio-ventricular block and ventricular ectopies or short-runs of non-sustained ventricular tachycardia (VT) (Fig. 2a). Then, a short stimulation burst at 20C40?Hz in the left ventricular (LV) epicardium was provided to trigger sustained VT (Fig. 2a,b). This strategy generated monomorphic sustained VTs with a duration distribution characterized by a mono-exponential decay (?=?7.4??0.6?was compared with a ChR2 stimulation in the center of the re-entrant circuit, as previously achieved with contact electrodes19 or optogenetic stimulation20, and with a activation, similar to the one achieved with electrical cardioversion shocks3,21. Before applying the ChR2 stimulation for interrupting VT, we characterized the response of the heart to different ChR2 patterns Avosentan (SPP301) manufacture in terms of illumination intensity, pulse duration (dose-response curves), as well as the evoked alteration in propagation maps (Fig. 3, Videos S6C9). We found that only the and the illumination protocols effectively generated activation times comparable to sinus rhythm while the and evoked activation maps displayed significantly delayed activation times. To prove that no effects are caused by the illumination itself, the same stimulation patterns have been also applied in hearts not expressing ChR2 and stained with the voltage-sensitive dye. Even though the highest energy-dose settings reported in Fig. 3 Rabbit Polyclonal to Akt (phospho-Ser473) was used, no alteration of the electrical activity Avosentan (SPP301) manufacture has been observed in the ECG (number of hearts?=?6). Figure 3 Optical manipulation of the cardiac conduction pathway. ChR2 stimulation was then applied in the setting of induced VT. Based on the distribution of VT durations (Fig. 2b), we awaited 5?s after the VT onset before applying the cardioversion protocols. We used a burst of ten pulses (5?ms of illumination time per pulse) at 10?Hz (1?s of total intervention) adjusting the laser power for every ChR2 stimulation pattern in order to assure a 100% capture success (Fig. 3). This choice of settings introduced a uniform threshold for all.