Optically Controlled Cardiac Pacer In Vivo

As an important part of the blood circulation system,the disorders in the heart’s rhythm can induce various serious heart diseases,including the atrioventricular block,cardiac arrest and bradycardia,which could cause chest spasm disease accompanied by angina pectoris that seriously endangers humans’ healthy life.Up to now,a variety of cardiac pacemakers have been developed by the researchers,including electric pacemakers,optogenetic pacemakers and near-infrared pacemakers etc.However,they were usually limited to the complex structure,low spatio-temporal accuracy,nonspecificity and invasiveness,thus limiting their wide applications in the biomedical field.Therefore,it is of great significance to develop a noncontact and noninvasive strategy to achieve a precise regulation of heart rhythm for the clinical diagnosis of cardiovascular diseases.In view of the above challenges,the scanning optical tweezers system,which was modulated through an acoustic-optic deflector(AOD),was used to precisely manipulate the 1064 nm near-infrared focused beam for a dynamic regulation of the heart rhythm in zebrafish embryo.By adjusting the specific angle of AOD,the incident laser’s spatial distribution was changed in real time after which it could be focused on the specific site of the zebrafish heart,thus achieving a precise stimulation for the cardiac myocytes in heart’s targeted region.Meanwhile,the focused beam could experience a quasi-static distribution by scanning the beam focus back and forth in a designed sequence through adjusting the AOD’s switching frequency,and thus,multiple heart’s locations could be simulated in a synchronous manner.Furthermore,we characterize the effects of laser power and irradiation position on the regulation capacity of cardiac rhythm in a quantitative manner,and then locate the region of cardiac pacemaker cells with a single-cell accuracy.This proposed strategy exhibits multiple advantages of noncontact and noninvasiveness,high spatio-temporal accuracy and flexible control,which can achieve a simultaneous stimulation of multiple target regions.More importantly,the arrhythmia symptoms of zebrafish could be improved by the proposed strategy,which will provide a new idea for the clinical treatment of heart disease with the near-infrared laser.