Aortic Valve Replacement (AVR)
How Is AVR Performed and Which Artificial Valve Is Best for Me?
The aortic valve is the main heart valve and an AVR is performed when it becomes diseased. Discover how an AVR is done and what the choices of artificial valves are.
Why Do I Need an Aortic Valve Replacement (AVR)?
The commonest reason for needing an AVR is for aortic stenosis or narrowing and stiffness of the aortic valve. This valve is the main one-way valve of the heart allowing the heart to eject blood under great pressure to supply the brain and body with oxygen.
Over time the aortic valve can narrow with a build up of calcium making it more difficult for the heart to pump enough blood to the body. Alternatively, the aortic valve can become leaky, known as aortic regurgitation, allowing blood to flow backwards into the heart after ejection.
Both conditions place strain on the heart over time and cause symptoms such as shortness of breath, chest pain or dizziness.
The only treatment for aortic valve disease is open-heart surgery with AVR, where the old valve is removed completely and replaced with an artificial valve.
What Sort of Artificial Aortic Valve is Used?
There are two main types of heart valve used in AVR; mechanical valves or so-called ‘tissue’ valves.
Mechanical valves are made from durable, synthetic materials and barring any malfunctions, will last a lifetime. However, these valves require life-long thinning of the blood or anti-coagulation with tablets called Coumadin, to prevent accumulation of blood clots on the valve. These clots can cause stroke or valve dysfunction. These valves also have a quiet ticking noise related to valve closure, however patients and spouses quickly become acclimatised to this sound.
Tissue or bioprosthetic valves are heart valves taken from animal (usually cow or pig) or human sources. They have been treated to reduce the risk of rejection. These valves do not require blood-thinning therapy but do have a limited life span that varies with age and other factors.
In general, bioprosthetic valves are implanted in older patients especially those >70 years old. Younger patients however, should discuss their requirements with their surgeons so as to choose a valve specific to their health needs.
How Is An AVR Performed?
A lot of the procedure is identical to coronary artery bypass surgery (which can also be performed at the same time as AVR if required). The breastbone or sternum is cut and the sac around the heart is opened.
The patient is placed on the heart-lung machine or cardio-pulmonary bypass that performs the job of the heart and lungs allowing them to be stopped for the duration of the valve replacement.
The diseased aortic valve is exposed by opening the aorta which is the main artery exiting the heart. The valve is then completely removed and the artificial valve is sewn into place.
The heart is restarted and separated from the heart-lung machine. Drain tubes are placed around the heart to monitor bleeding and the breastbone is closed using fine stainless steel wires which hold it in place until the bone is healed (approximately 6 weeks).
Usually, an AVR takes from 3 to 5 hours. The patient is then taken to the intensive care unit for monitoring. Average hospital stay after AVR is 4-7 days. Recovery from AVR is a gradual process and takes up to 3-6 months.
Minimally Invasive Surgery
Surgeons are always pushing to minimise the trauma associated with open-heart surgery. In some centres, AVR is being performed through smaller incisions and early work is being done on performing this procedure endovascularly or entirely through the groin arteries, similar to a coronary angiogram.
These minimally invasive techniques are not suitable for all AVRs nor for all patients, and some of these newer procedures are only available in specific centres. Patients should discuss these options with their surgeons.
