A slow heart rate, also known as bradycardia, does not typically cause the heart to "flitter." However, you might be referring to a sensation of fluttering, which could suggest a type of irregular heartbeat, such as atrial fibrillation or other types of arrhythmias.
It's essential to differentiate between a slow heartbeat and the sensation of fluttering. A slow heart rate may be a normal response in athletes or during sleep, while fluttering or palpitations are often associated with various heart conditions. If you're experiencing unusual heart sensations, it's best to consult a healthcare professional for an accurate diagnosis and appropriate guidance.