To explain it in simple terms, your heart doesn’t get its beating signal from the brain, the sinus node takes care of that and is located in the heart. What the brain (and other parts of your body) does is tell the heart to beat faster or slower when required. So the kind of paralysis caused by the octopus doesn’t affect your heart because it doesn’t need to use any external pathways to send the signal to the muscle to contract.
To explain it in simple terms, your heart doesn’t get its beating signal from the brain, the sinus node takes care of that and is located in the heart. What the brain (and other parts of your body) does is tell the heart to beat faster or slower when required. So the kind of paralysis caused by the octopus doesn’t affect your heart because it doesn’t need to use any external pathways to send the signal to the muscle to contract.