Cardiac Pacemaker - Springer Nature

Study of the optimum fluoroscopic angle for the implant fixation test of a leadless cardiac pacemaker

The Micra TPSu2122, China's first leadless pacemaker, is the first leadless pacemaker listed. According to various implantation sites, the best fluoroscopic angle for the intraoperative fixation test is selected, depending on the test's early safety and effectiveness of the procedure after implantation. The average fluoroscopy duration for finding the best angle of fixation test was 270. 4 vs. 338. 1 mGy, which was less than that in group A, and referring to the average angle.

Source link: https://doi.org/10.1007/s10554-022-02686-w

Glutamate drives ‘local Ca^2+ release’ in cardiac pacemaker cells

Cardiac contraction is triggered by the spontaneous firing of SAN pacemaker cells. We established a tight correlation between glutamate accumulation and LCR occurrence using a glutamate sensor, revealing a potential association between glutamate and LCRs. In both intact and permeabilized SANPCs, intracellular application of glutamate significantly raised the LCRs. We found that mitochondrial excitatory amino acid transporter 1 -dependent mitochondrial glutamate import supported ROS generation, which in turn contributed to the degradation of Ca2+-handling proteins, resulting in increased LCRs. EAAT1 depletion reduced both the spontaneous firing rates of isolated SANPCs and the heart rate in vitro and in vivo, as well as the heart rate, highlighting the central role of EAAT1 as a glutamate transporter in cardiac rhythm regulation. In conclusion, our findings reveal that glutamate acts as an LCR igniter in SANPCs, providing a critical piece to the coupled-clock model that explains spontaneous firing's origins.

Source link: https://doi.org/10.1038/s41422-022-00693-z

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