When i listen to my heart sounds with a stethoscope i hear that my heart speeds up when i inhale deeply. is this normal? is this respiratory arrhythmia? why does my heart change rate within respiratory cycle?

Wonderful pump: Our heart is a pump that keeps pumping from before we're born until we die (and even beyond the heart owner's death in some cases). Suppose you take a deep breath. That creates a vacuum inside the chest, leading to less flow of blood into the heart, leading to a smaller quantity of blood leaving the heart per pump stroke. Increasing the rate compensates for less blood per pump stroke.