By Pragnesh Joshi, Cardiothoracic Surgeon, Nedlands
True incidence and prevalence of aortic root aneurysm is not exactly known. Pooled incidence and prevalence of thoracic aortic aneurysm was reported to be 5.3 per 100,000 individuals per year.
The aortic root replacement is considered a standard of care when surgery is indicated and includes replacement of native aortic valve, aortic sinuses and ascending aorta along with re-implantation of native main coronary arteries.
Aortic aneurysm affects mainly the aortic wall and aortic sinuses. Quite often, native aortic valve is not diseased or, at most, there is aortic regurgitation. Aortic valve replacement in this situation can be avoided by re-using a patient’s native valve.
However, in most cases even when the aortic valve is normal, it is replaced with artificial mechanical or tissue prosthesis while performing aortic root replacement due to lack of expertise.
David’s procedure is an aortic root replacement operation where in patients’ native aortic valve is used and re-implanted instead of a mechanical or tissue valve. This operation was introduced by Dr Tiorne David from Canada.
Also known as Valve Sparing Aortic Root Replacement (VSARR), it allows patients to retain their native valve, avoiding the associated lifetime complications of an artificial valve.
Indications
Indications for David’s procedure overlaps with indications of aortic root replacement. Current threshold to advise aortic replacement surgery is 5.5 cm diameter. However, the indications need to be tailored to a patient’s medical background.
Candidates for David’s procedure need good quality, native valve and a surgeon experienced in performing the procedure. It can be considered in:
- patients with high-risk features
- at diameter of 4.5-5.0cm in patients with connective tissue disorders and high-risk features
- at diameter of 4.5 in patients with family history of dissection of aorta
Aortic replacement surgery can be considered at 5.0cm in diameter if performed by experienced aortic surgeon. While evaluating patient for aortic root surgery, indexed aortic diameter and cross-sectional area ratio should be taken into consideration.
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Who is not suitable
The aortic valve must be of good or reasonable quality for consideration of reimplantation.
Those who are not suitable include patients with aortic stenosis, infective endocarditis with features of valve destruction, aortic valve with signs of advanced degeneration such as calcification or retraction of leaflets, quadricuspid or unicuspid aortic valve, and multiple large fenestrations in leaflets.
A bicuspid valve can be re-implanted as long as they are of good quality and devoid of calcification. The long-term results are very good.
Who should do David’s procedure
Most David surgeons should be experienced aortic root surgeons, which requires close to 70 aortic root replacement surgeries. From published data, one can say that the risk of valve related reoperations, bypass time and cross clamp time tends to be better after 30-40 cases per surgeon.
This means that the surgeons who should perform David’s operation should be proficient in aortic root surgeries and should be undertaking this operation on a regular basis.
Key messages
- Normal aortic valve does not need to be replaced at the time of aortic root replacement surgery. The valve can be spared and reused.
- All patients with non-calcified valves undergoing aortic root replacement surgery should be evaluated for suitability for David’s procedure.
- Advantage of David’s procedure is long-term durability with no need of anticoagulation for valve.
How is the procedure performed?
The standard approach is via median sternotomy under general anaesthesia. Highly experienced surgeons may be able to offer this operation via mini sternotomy.
The procedure requires cardiopulmonary bypass and requires the heart to be stopped. Native ascending aorta and aortic root tissues are excised while leaving native aortic valve attached to aortic annulus.
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Left and right main coronary arteries are separated, the aortic root and ascending aorta are reconstructed using a polyester tube graft. The native aortic valve is reimplanted within this graft along with coronary arteries.
Valve is tested for symmetry and function using aortoscopy. Prior to closing the chest, transoesophageal echocardiography is performed to check the form and function of the valve repair. The post operative course is the same as any other cardiac surgery.
Long-term results
The long-term results of this operation are excellent, both in terms of survival and freedom from valve related reoperations.
Freedom from reoperation is close to 90% at 10 years and 85% at 15 years. This closely matches with conventional aortic root replacement with artificial heart valves, however eliminates the risk of bleeding or thromboembolism which is more with artificial heart valves.
Another advantage of native aortic valve is lifelong lower risk of endocarditis compared to artificial heart valves. Every artificial heart valve comes with lifelong risk of endocarditis and thromboembolism.
The mechanical valve comes with added risk of bleeding. Native aortic valve does not require anticoagulation and risk of stroke from the valve would be no different to anyone else with native valve.
Author competing interests – nil
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