Case history

Tam Mei-lan, 86, was out of breath and out of options when she consulted Dr Elaine Chau, a cardiologist at the Hong Kong Sanatorium and Hospital.

The health crisis began when sudden chest pain and severe breathlessness landed Tam (whose name has been changed to protect her privacy) in hospital. She had suffered a heart attack because not enough blood was reaching her heart.

Three coronary angioplasties followed, in which a total of eight stents (mesh tubes) were inserted into the arteries leading to her heart to keep them open.

After her third angioplasty, she suffered a sudden cardiac arrest, where blood stopped circulating in her body because her heart failed to contract sufficiently.

Doctors worked frantically to resuscitate her, fracturing a few of her ribs in the process.

But these frightening events were not what vexed Tam the most. She had been enduring sudden and repeated episodes of chest pain and severe breathlessness, especially at night. Fighting for air distressed her so much that she was afraid to sleep.

She even used a breathing aid, or bilevel positive airway ventilator, to help her while she was sleeping. Still, some of the attacks were so vicious and unrelenting that she had to be admitted to hospital every few months.

Her doctors had no satisfactory explanation or solution for her, so she sought out Chau for a second opinion.

When Chau did a physical examination of Tam's carotid artery in her neck, she noticed an irregularity in the pulse. Using a stethoscope, Chau heard a murmur in Tam's heart, indicating turbulent blood flow within it. While murmurs may be harmless, they could also signal a structural abnormality in the heart.

Tam's besieged heart also beat in an irregular rhythm - a condition known as arrhythmia.

Chau needed a closer look at the structure of Tam's heart. She performed an echocardiogram (ECG), which uses ultrasound waves to produce images of the organ - its chambers, valves and surrounding structures.

The ECG showed that Tam's aortic valve - a three-flap tissue that opens to allow blood to flow from the left ventricle into the aorta, and closes to prevent the blood from flowing backwards - was thickened and caked with calcium deposits. Because of this, the valve could not open sufficiently wide to maintain proper heart function.

Tam was suffering from severe aortic stenosis, or the abnormal narrowing of the aortic valve. This meant Tam's heart had to work extra hard to pump blood through, thereby increasing its demands for oxygen. When the heart fails to get the oxygen it needs, chest pain, or angina, occurs.

The increased pressure in the heart also causes increased pressure in the lungs, which has to return oxygenated blood to the heart.

Tam's breathlessness was caused by the increased pressure in the blood vessels of the lung. That she was breathless when lying down indicated that the disease was at an advanced stage and that the heart muscles were unable to compensate for the increased pressure.

Tam was at risk of sudden death. The ECG results also showed that Tam's open valve area was only 0.7sq cm. A normal valve opens to about 3sq cm. Her condition was critical, and she needed a new valve if she was to have any chance of survival.

However, given Tam's advanced age and her other heart conditions, she had a 40 per cent to 50 per cent chance of dying on the operating table if she were to undergo a standard open aortic valve replacement surgery.

The procedure would involve making a 20cm incision in her chest, cracking open her sternum and placing her on a heart-lung machine. Given her chances with open heart surgery, however, no surgeon would touch her.

Thankfully, Chau had an alternative for Tam. A minimally invasive procedure called transcatheter aortic valve implantation (Tavi) had become available in Hong Kong about three years ago.

With Tavi, Tam's diseased valve could be replaced by only making a 2cm to 3cm incision in the groin. A catheter (hollow tube) would be inserted into her femoral artery and manoeuvred up the arterial highway and into her heart under guidance from X-ray and ECG visuals.

A 5cm-long metal stent bearing a 26mm-diameter valve was delivered up the catheter and positioned where her calcified valve was. The new valve expanded, opening up and permanently replacing the diseased one.

Tam's femoral artery needed to be at least 6mm in diameter to accommodate the catheter. A tiny woman who is less than 1.5 metres tall and weighs 40kg, Tam barely made it with a 7mm-wide artery.

A slew of scans and tests followed to enable Chau to map out the arterial route before the procedure. The three-hour-long surgery went smoothly, and Tam was up and about 24 hours later.

Six months after the operation, Tam has not suffered a single attack of breathlessness nor has she had to be admitted to hospital.

Chau notes that Tavi has given severe aortic stenosis patients such as Tam - who would otherwise have no tenable treatment options - a fighting chance.

Although the procedure does carry some risks, such as a heart attack, stroke, damage to the heart or arteries, infection and so on, Tavi also offers fast recovery and a good outcome for patients.