This graphic video shows a heart swollen to three times its normal size due to cocaine use.
The film shows an enlarged organ which has just been removed from a patient who abused the drug for more than 15 years.
The heart continued to beat for more than 25 minutes outside the body, doctors from Medspiration, who uploaded the video, said.
This is far longer than the 60 seconds it normally takes to lose oxygen and stop beating and shows how much the drug has ravaged the organ.
Dr Klaus Witte, a consultant cardiologist at Leeds General Infirmary, told the Daily Mail this was because it was probably pumped full of medical stimulants to keep it beating - and the patient alive. But, he said, the video shows clearly how badly cocaine damages the heart.
"This heart, it's not beating. Those are not normal contractions," Dr Witte said. "It's twitching in a desperate way."
Effects of cocaine
He said cocaine causes changes to the structure of the arteries and the heart, and this, in turn, causes the heart to swell.
Studies have shown cocaine users have higher blood pressure, stiffer arteries and thicker heart muscle walls than non-users, all of which can cause a heart attack.
"Every tablet I use for treating cardiac conditions, cocaine does the opposite," Dr Witte added.
"Cocaine changes the body's lipid (fat) profiles, makes the blood sticky, makes the heart work harder and faster, changes the body's hormonal profile. It leads to heart attacks, strokes and heart failure."