Over the span of a lifetime, the human heart beats more than two billion times. With each beat, flexible valves within the heart’s chambers open and shut to prevent blood flowing backwards.
With advancing age these valves can start to fail; the opening can become narrowed or the valve may leak. Narrowing of the aortic valve – known as aortic stenosis – is one of the most common forms of heart disease.
It is caused by thickening, fusion and even calcification of the valve and is common in the elderly affecting over four per cent of people over 80 years of age, says Dr Michael Mullen, Consultant Cardiologist, The Heart Hospital, University College London, UK.
“Aortic stenosis can be tolerated quite well with few symptoms for many years. However, eventually symptoms of breathlessness on walking, angina or collapse may develop. When this happens it is important to get treatment quickly as untreated symptomatic aortic stenosis is progressive and often fatal.”
“Aortic stenosis kills, and kills rapidly,” says Dr Rod Stables, The Liverpool Heart and Chest Hospital,UK. “After the onset of symptoms, 50% of patients will be dead two years later [unless treated]”
There are no drugs to remedy aortic stenosis. In many cases the faulty valve is replaced via open heart surgery. This involves opening the chest, stopping the heart and putting the patient on a heart-lung bypass machine during the procedure.
However exactly ten years ago a new treatment called Transcatheter Aortic Valve Implantation (TAVI) was developed. This allows a new valve to be implanted in the heart via a tube called a catheter. This catheter is inserted into a small incision in the groin or chest and threaded through major blood vessels into the heart.
The new valve is mounted within in an expandable metal frame that opens and anchors the valve in the correct place in the still beating heart. The catheter and guide wires are then removed.
Globally more than 50,000 of TAVI procedures have now been completed. Cardiac teams performing this technique met this week in London at ‘PCR London Valves 2012’, the official valve meeting of the European Association for Percutaneous Cardiovascular Interventions (EAPCI).
Together with other experts, Dr Mullen and Dr Stables briefed medical journalists on new developments in TAVI at a London Workshop sponsored by Edwards Lifesciences, one of the companies currently involved in heart valve manufacture, research and development.
The Workshop was chaired by Mr Vinayak Bapat, Consultant in Cardiac Surgery Guys and St. Thomas’ Hospital. He said that TAVI improvements over the last decade have focused on making the technique less invasive and less complex, with fewer complications for the more elderly and frailer patients who typically receive TAVI because they cannot have open heart surgery due to poor health or technical difficulties.
Given the seriousness of aortic stenosis, it’s surprising that many patients receive no treatment at all, and are never referred to specialist units by their primary care physicians, said Dr Stables. He attributed this to ‘inertia’ or ‘lack of knowledge’ about potential treatments. Turning to the use of TAVI in the UK, he said that uptake remains very low by European standards – with a rate of 19 per million population, versus an EU average of 41 per million, and well below the EU ‘leader’ Germany, which uses the technique in 97 per million of their population (although some clinicians believe the technique may be overused in Germany).
“TAVI today is an effective treatment option. It shows an evidence base in quality randomised trials, is supported by guidelines* and offers a new treatment option. Despite this, UK TAVI provision shows low volume by European standards with a patchy service over the UK,” he concluded. He added that uptake needed to increase to meet the needs of ‘forgotten’ or ‘ignored’ patients.
Dr Mullen was more upbeat and predicted a ‘stellar’ future for TAVI, with a new generation of valves and delivery systems currently under investigation. He predicted that a ‘tipping-point’ would occur at which TAVI would become a cheaper option for health care providers, than open heart surgery.
*TAVI was included in the recently published European Society of Cardiology (ESC)/European Association for Cardio-Thoracic Surgery (EACTS) Guidelines on the Management of Valvular Disease. In the UK, NICE published Interventional Procedure guidance in March 2012.
Written by Dr Ian Mason