Sinus rhythm electrocardiogram
A contraction, from the Greek [διαστολη] (systolí) meaning “expansion, dilation, drawing out, or prolongation”, also [διαστέλλειν] (diastéllein) meaning “to open, expansion”. When used in music, it means "a pause".
It refers to the dilation of the heart. If you analyze a normal heartbeat (sinus rhythm), there are two diastoles: an atrial diastole and a ventricular diastole. The term diastoleis usually used in reference to the ventricular diastole.
Diastole was first recognized and named by Herophilus of Alexandria (325-255BC), most probably trough animal vivisection. Herophilus was accused of animal vivisection and the dissection of human cadavers. Because of this, some call Herophilus "The Father of Anatomy".
Galen of Pergamon (129AD - 200AD) used the term [διαστέλλεσθαι] (diastéllesthai), also meaning “expansion”.
The word in English was first used in the 16th century. The modern pronunciation in English follows the Greek pronunciation by ending the word in a long “e” as in “to be”.
Sources
1. "The Origin of Medical Terms" Skinner, HA 1970 Hafner Publishing Co.
2. "Medical Meanings - A Glossary of Word Origins" Haubrich, WD. ACP Philadelphia
3. "Dorlands's Illustrated Medical Dictionary" 26th Ed. W.B. Saunders 1994
4. "Greek anatomist Herophilus: the father of anatomy" Si-Yang, N. Anat Cell Biol. 2010; 43(4): 280–283
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