Sarah May, 61, had trouble walking. Although she is a vivacious and active woman who loves travelling, she could not walk far before her legs would cramp up. Her feet were also constantly cold. But May (real name withheld for patient confidentiality) knew very well what was ailing her.
Fourteen years ago, she had been diagnosed with peripheral arterial disease (PAD), a common circulatory problem in which the blood flow to her legs was reduced because her arteries had been narrowed by a build-up of fatty material - a condition called atherosclerosis.
Atherosclerosis is more commonly known to affect the coronary arteries of the heart and in the brain, where they can cause heart attacks and strokes. However, atherosclerosis is a systemic disease and can also take place in arteries supplying blood to other parts of the body, such as the legs, arms, lungs and kidneys.
In PAD, the reduced blood circulation to the legs can cause painful cramps when walking, leg weakness and numbness, coldness in the feet, poor wound healing, ulcers and even gangrene.
Although PAD is not well known - only 26 per cent of respondents to an American phone survey said they were familiar with the condition - it carries a health risk to patients. One in five PAD patients will suffer death for cardiovascular reasons, experience a heart attack or stroke or require admission to hospital. The risk of death is increased in PAD patients whether they exhibit the symptoms or not.
May had all the classic risk factors for developing PAD - diabetes, hypertension and a smoking habit. In 1996, she underwent a balloon angioplasty - in which a deflated balloon on a catheter was placed into the narrowed arteries in her leg and inflated to widen the constricted area before being removed.
Although her condition improved for a while, May persisted in her smoking habit, and the arteries re-narrowed, causing the walking difficulties.
Late last year, after more than a decade of bearing with the revived symptoms, May finally sought help.
She was referred to assistant professor Dr Bryan Yan Ping-yen, a specialist in cardiology in Chinese University's department of medicine and therapeutics.
A previously conducted computed tomography (CT) angiogram showed Yan that May's femoral arteries were blocked at the points where they joined with the abdominal aorta.
Yan explains that because the blockages occurred over time, the body adapts and gets blood to her legs via other blood vessels. However, those other routes are less efficient at moving blood - Yan likens it to travelling via narrow back alleys instead of cruising down the highway - resulting in her pain.
If May's condition is untreated and deteriorates further, she could develop ulcers and gangrene in her legs. At that point, she could lose her limbs.
Although bypass surgery could have treated her condition, it was a big operation that involved rerouting blood flow around the blocked arteries and would usually require general anaesthesia and a longer recovery period.
Instead, Yan suggested a minimally invasive and lower risk endovascular therapy to clear the blockages and insert two stents to keep the arteries open and allow blood to flow normally again. This procedure would only require local anaesthesia, and May could stay awake throughout the process.
As May's case was very severe given the long history of her condition, the plaque that closed off blood to her femoral arteries was very hard - 'like concrete', Yan says. He had to insert catheters through her elbow and both her femoral arteries to attack the plaque from above and below.
Yan then had to chip his way through the plaque with pointy wires in the catheters. After the arduous task of chiselling through the rock-hard plaque and unclogging the arteries, Yan then inserted two stents where the aorta splits into the femoral arteries, forming an inverted V-shape to keep the blood vessels open. The way the two stents touch gave rise to the moniker 'kissing stents'.
The procedure was a success. That night, May noticed that her feet were no longer cold, and the very next morning, May could walk without pain and cramping.
A slight, though rare, complication arose when a clot formed in her arm after the procedure and needed to be removed in a separate operation the following week.
With the circulation restored, May relished her newfound mobility and was soon taking overseas trips. However, she still needs to keep her diabetes, hypertension and smoking habit in check.
Yan says PAD can be easily diagnosed by using a non-invasive method called the Ankle-Brachial Index or ABI. In it, a person's blood pressure at the ankle is taken and divided by the blood pressure at the arm.
A healthy person's ankle blood pressure should be the same or higher than the blood pressure in the arm, and the ABI should be above one. An ABI of less than 0.9 indicates disease, and an ABI around 0.5 would already be accompanied by severe symptoms.
As PAD is a lifestyle-limiting disease, and patients carry an increased risk of death by cardiovascular causes, heart attack or stroke, Yan says it is important - and easy - to get an early diagnosis and treatment of this disease.