The heart rate is closely related to a branch of the nervous system called the autonomic nervous system. We can’t control how fast it goes because it is deeply wired in the brain. The chemical alteration caused by alcohol will also cause a rapid heartbeat. The inhibitory signals in the brain become affected by alcohol addiction, and it no longer regulates the heartbeat frequency as it should. There’s not enough impulse to slow it down because you’re relying on alcohol to do it. Thus, tachycardia ensues.