rubatosis

Presumably rubato +‎ -osis. Coined by American author and neologist John Koenig in 2012 as part of his Dictionary of Obscure Sorrows project.

• (Received Pronunciation) IPA^(key): /ˌɹuːbɑˈtəʊ.sɪs/
• (General American) IPA^(key): /ˌɹubɑˈtoʊ.sɪs/
• Rhymes: -əʊsɪs

rubatosis (uncountable)

1. (neologism) The unsettling awareness of one's own heartbeat
   • 2015 September, Gustaf Vonsheilds, Palm Spring Whispers, Lulu.com, →ISBN, page 105:

     Amador rocked me slowly in that amniotic tranquility and I started to get sleepy. I could hear the unsettling rubatosis of my beating heart.

   • 2016, Asif Anwar, Fainting Pulse: ICU Chronicles, →ISBN, page 113:

     Avis stopped in his tracks and wheeled around, thinking something had gone wrong—a moment of rubatosis.

   • 2019, Jonna Wahl, Bloody Bloom, →ISBN:

     My skin brushed up against his soft hand, sending lightning throughout my body and a strong feeling of rubatosis.

While defined by Koenig as a sensation (“unsettling awareness”), some authors employ the term as a synonym of palpitation – not the sensation but the heartbeat itself.

• Koenig, John (2021), “rubatosis”, in The Dictionary of Obscure Sorrows, New York: Simon & Schuster, →ISBN, page 60