Adams-Stokes SyndromePacemaker, ArtificialSinoatrial NodeCardiac Pacing, ArtificialHyperpolarization-Activated Cyclic Nucleotide-Gated ChannelsBiological ClocksBradycardiaEquipment FailureHeart BlockSick Sinus SyndromeEquipment SafetyArrhythmia, SinusMyocytes, CardiacCyclic Nucleotide-Gated Cation ChannelsInsurance, AccidentHeart Rate