New research shows that if you quit smoking your blood vessels will return to normal - but only after a 10-year wait, writes Dick Ahlstrom.
Smokers who quit the habit can have blood vessels as healthy as those of a non-smoker, according to a new medical study. Unfortunately the renewal process can take up to 10 years.
The important new research comes from a group at St James's Hospital, Dublin, who have delivered a sequence of studies related to tobacco smoke and its effects on blood vessels. The latest was published last month in Hypertension, the Journal of the American Heart Association.
"We are interested in smoking because it has a huge impact on cardiovascular disease," explains the lead author of the research, Dr Azra Mahmud.
A lecturer in cardiovascular pharmacology in the department of therapeutics and hypertension clinic in Trinity College Dublin's Centre for Health Sciences at St James's Hospital, her work focuses on how smoking can change the performance of blood vessels.
In particular she studies how the stiffness or rigidity of the blood vessels increases in people who smoke and in those exposed to tobacco as passive smokers. "People who become chronic smokers have much different cardiovascular systems than non-smokers," she says. "Once people start to smoke the effect happens very quickly."
Even before damage is seen in the lungs, the normally flexible arteries begin to lose some of their spring. They become stiffer, something that causes blood pressure to rise and ultimately causes damage to the heart.
Previous studies by her group have shown how quickly smoking can trigger the blood vessel changes and how passive smokers also develop the changes seen in smokers.
Her latest study, conducted with PhD student Dr Noor Jatoi and research colleagues Dr Paula Jerrard-Dunne and Prof John Feely, demonstrated that the blood vessels of smokers can go back to near normal in a person who kicks the habit.
The team assembled a study of more than 550 people including non-smokers, current smokers and smokers who had quit anything from one to more than 10 years previously.
They used completely non-invasive methods for studying the flexibility of the vessels based on measurements taken at the surface of the skin. The two methods used both depended on tracking the speed of the "wave front" of circulating blood as the heart pulsed. The speed achieved by the advancing wave front is dependent on the flexibility of the vessels, says Mahmud.
If the blood vessel is flexible the wave moves slower, but if it is rigid it moves faster, she explains. She likened it to water moving through a rubber vs a lead pipe.
"If you have a rubber pipe and a lead pipe the water travels in the lead pipe faster than in the softer pipe. That is exactly the same as in your body."
This speed is important for a number of reasons. The heart beats and then rests itself before the next beat. During this time the heart receives its own blood supply so the short rest period is important.
If the vessels are rigid due to smoking, the blood travels more quickly through the circulatory system, returning to the heart more quickly and shortening the heart's rest period. This forces it back into a beat too quickly and also interferes with the proper delivery of its own blood supply.
"The heart's blood supply goes down and when this happens the heart has to change to deal with the extra pressures," says Mahmud. Over time the effect can raise blood pressure and also leads to an enlarged heart. "As the blood pressure goes higher it becomes a vicious circle," she adds.
The study included current smokers and former smokers at less than one year since stopping, between one and 10 years after stopping and more than 10 years since kicking the habit.
It indicated that after 10 years the flexibility of a former smoker's blood vessels matched that of people who had never smoked. Other important findings emerged however. All of those involved had existing high blood pressure, but no other underlying problems such as blocked arteries.
"To the best of our knowledge, this is the first study to show that in untreated [ bloodpressure] patients, a population characterised by already stiff vessels, chronic smoking further increases arterial stiffness," the authors report.
"We also think that, as the increased [ vessel] stiffness is independent of blood pressure, the effects of [high blood pressure] and smoking on the vascular wall may be cumulative."
The fact that this is reversible over time at least provides some cause for optimism.