In the 18th century, blood pressure was measured in horses by the Revr. Stephen Hales, an Anglican minister. He did this by the direct cannulation of large arteries and obtained values not that much different from those we know today. The methods he used developed out of his work in measuring sap pressure in trees.
Some years earlier, Richard Lower had discovered the oxygenation of the blood.
Late in the 18th century, William Withering discovered digitalis in the the foxglove plant. It has been used for over 200 years to treat heart failure, or 'dropsy', as it was called.