The study hopes to unravel the link between stress and heart disease
The British Heart Foundation is funding an investigation looking at how depression and stress could damage blood vessels.
Every year, tens of thousands of people in the UK are diagnosed with some form of coronary heart disease - it remains the biggest killer.
It happens when deposits gather on the sides of the arteries supplying the heart muscle, which eventually narrow and constrict blood flow.
Experts still do not know which external and internal factors cause the deposits to form and cause this hardening of the arteries.
Researchers think that long-term stress may be causing an "over-reaction" by the body's immune system, which causes inflammation in the tissues, which can cause long-term damage.
Professor Michael Frenneaux, who is leading the research, said: "When the body is under stress it produces certain chemicals that, over time, may be harmful to our arteries by causing inflammation.
"We believe that being depressed may lead to prolonged over-activity of the body's 'stress response' and this could be why depression can increase the risk of coronary heart disease."
The experiment will involve volunteers taking a drug which blocks the chemicals normally involved in the stress response.
The team is hoping that this drug will improve artery function.
Greater risk
The British Heart Foundation's regional director for Wales, David Napier, said: "Stress in short bursts is not harmful for the heart, and is a natural part of everyday life.
"However, long term stress or depression is a different matter.
"BHF statistics show that people show that people with less control over their work, and those who are depressed or have an angry personality are at a greater risk of coronary heart disease."
It is estimated that 12% of the population suffers from depression in some form.