Aortic Valve

Heart valves open and close to allow the blood to flow in and out of the four chambers of the heart in the right direction. If they are damaged (through infection or disease) they will either not open properly or not close tightly enough and leak. Both problems mean the heart has to pump harder. A new aortic valve relieves the strain on the heart and aims to ease symptoms such as breathlessness and chest pain.

              normal-aortic-valve                   calcified-aortic-valve-stenosis

        Healthy Tricuspid Aortic Valve               Aortic Valve Stenosis

The severity of the valve disease is based on physical examination and the echocardiographic  findings. The indications for intervention are based on the following:

  • the presence or absence of symptoms,
  • the  severity of valvular dysfunction,
  • the  response of the heart to he presence of valvular disease (dilatation, hypertrophy, failure),
  • the effect on the pulmonary or systemic circulation, and
  • the changes in heart rhythm.

All patients with heart valve disease are assigned to one of the new 4-stage.

  • A (at risk)
  • B (progressive)
  • C (asymptomatic severe)
  • D (symptomatic severe)

Aortic regurgitation

Bicuspid (bileaflet) aortic valve (BAV)

Bicuspid (bileaflet) Aortic Valve disease (the disease where the aortic valve has two instead of three cusps (or otherwise known as leaflets) is also a heritable disorder, is known to have an increased risk of ascending aortic aneurysm as well. Bicuspid aortic valve (BAV) disease is the most common congenital cardiac disorder, being present in 1-2% of the general population. Approximately 9% to 15% of first-order family members also have BAV disease, with men and women equally affected within family members. The heritability of BAV disease is more than 80%, and approximately 9% to 15% of first degree relatives have the disorder. Therefore, it is recommended that first-degree relatives of patients with BAV are screened with echocardiography

In BAV disease, valvular complications (aortic valve stenosis or regurgitation) progress at their own independent rates, different from the rate of progression of the bicuspid aneurysm. Patients with pure/predominant BAV aortic regurgitation (10% to 15% cases of BAV) tent to be younger and males.

BAV aortopathy and aortic aneurysm is a common finding in patients with BAV disease and as high as 40%. Aneurysmal dilatatation in BAV aortopathy may occur in the aortic root, the tubular ascending aorta (most common, 60-70%), the proximal aortic arch, or any contiguous combination of these three. Although only 5% or less of patients with BAV will have aortic dissection over a lifetime, so BAV is an important cause of aortic dissection. Patients with BAV and aortic valve disease (stenosis or regurgitation) are at increased risk of rupture and dissection of the aorta. Evidence increasingly demonstrate that BAV with aortic regurgitationcan be more malignant phenotype than BAV with aortic stenosis BAV, with a higher risk (10x) of aortic dissection.

BAV pathologyBAV aortopathy consists of premature changes to the consistency of the aortic wall (cystic medial degeneration) in approximately one half of the patients who had surgery for BAVs. Valve mediated blood flow dynamics and regional wall stress differences are associated with changes in regional aortic wall histology and proteolytic events which are known to contribute towards the premature changes to the consistency of the aortic wall. Both genetic predisposition and rheological abnormalities may coexist, resulting in diverse clinical presentations, with distinct natural histories.

Prophylactic aortic repair is recommended to prevent catastrophic aortic complications, particularly aortic dissection and rupture. Although aortic diameter is currently the major criterion for timing of elective surgical repair of ascending aortic aneurysms, it is an imperfect predictor of aortic dissection or rupture (50 mm aorta could represent moderate dilatation in a large man but may be severe dilatation in a small woman) and correction for body size parameters should be taken to account. The ratio of aortic cross-sectional area divided r2 π (cm2)/ by height [ratio height (m)] has also been proposed as a method to correct for body size with a cutoff of 13cm2/m  for the tubular ascending aorta and 10cm2/m for the root exhibited superior predictive accuracy for the occurrence of dissection than absolute aortic diameter cutoffs.

Indications for Elective Surgical Repair of DilateAscending Aorta/Aortic Root/Aortic Arch Associated With Bicuspid aortic valve (BAV)
  • Repair of the ascending aorta/root is recommended when:
    • The diameter is >5.5 cm in patients with no risk factor
    • The diameter is ≥50 mm and no risk factors, when the patients are at low surgical risk and operated on by an experienced aortic team in a center with established surgical results.
    • The diameter is <5.0 cm associated with any of the following:
      • Root phenotype or predominant aortic valve regurgitation,
      • Uncontrolled hypertension,
      • Family history of aortic dissection/sudden death,
      • Aortic coarctation,
      • Aortic diameter growth >3 mm/y
      • Small adult body size (especially if they have Turner’s syndrome), indicated by either of the following:
        • aortic cross-sectional area to height ratio of > 10 cm2/m
        • Indexted aortic diameter of >2,75 cm/m2
      • Women planning pregnancy because of an increased risk of aortic complications in such patients
      • Patients with BAV aortic regurgitation and root phenotype of aortic dilation at an aortic diameter of 5.0 cm. Such patients may particularly benefit from a valve-sparing aortic root replacement (David) operation, if done in an experienced center with known outcomes.
  • Concomitant repair of the ascending aorta/ root should be performed when the aortic diameter is ≥45 mm in patients undergoing cardiac surgery.
  • Repair of the aortic arch is recommended:
    • When the aortic arch diameter is ≥55 mm.
    • Concomitantly for patients undergoing cardiac surgery for other reasons and have an aortic arch diameter of ≥50 mm
    • Concomitantly for patients undergoing cardiac surgery for other reasons and have aortic arch diameter of ≥45 mm, provided the patients are at low surgical risk and operated on by an experienced aortic team with established surgical results.
    • For patients undergoing elective aortic arch repair by an experienced aortic team with established surgical results.

Surgery to the aortic valve

The reasons for aortic valve intervention are: to improve symptoms, to prolong survival, and to reduce the risk of complications. The operation involves replacing a damaged valve in your heart with a mechanical valve (made from man-made materials) or a tissue valve (usually from a cow or pig). requires a hospital stay of 5-7 seven days and is done under general anaesthesia. This means you will be asleep during the procedure. Once the anaesthetic has taken effect, your surgeon will make a cut (traditionally about 25cm long, mini sternotomy about 10-12cm long), down the middle of your breastbone and open the ribcage to reach the heart. The heart is slowed or stopped (using medication) and blood is re-routed to a heart-lung machine. This takes over the pumping action of the heart and lungs, adding oxygen to the blood and maintaining the circulation.

Your surgeon will open the heart chamber, remove the faulty valve and sew in a replacement. Blood is then redirected back to your heart and the heart is restarted. The breastbone is re-joined using wires and your chest is closed using dissolvable sutures, stitches or staples. The operation usually takes about 2-3 hours.

Biological valves for aortic valve replacement

BioprosthesisThere are a variety of biological valves which can be used for aortic valve replacement. Most are made from cow or pig tissue. The main advantage of this type of valve is that it is associated with a low risk of blood clot formation which if occurs, can cause the valve to malfunction or cause a stroke. The main disadvantage is that these valves have a limited durability as compared with mechanical valves. In other words, they will wear out given enough time. The rate at which they wear out depends on the patient’s age. A young boy might wear out a valve in only a few years, while the same valve might last 10-15 years in middle aged person, and even longer in a patient over the age of 70. Of course, as we grow older we expect that we will not need the valve for as many years as our life expectancy is less. The general consensus is that a tissue valve is best used in patients from the age of 55-70 years.

Mechanical valves for aortic valve replacement

There are a number of excellent mechanical prostheses available today. All perform equally well. The principle advantage of mechanical valves is their excellent durability, made from carbonised metal they simply do not wear out! Their main disadvantage is that blood cells are likely to form clots on the surface of the metal. If this happens the valve will not function normally. Patients with these valves must therefore take anticoagulants (blood thinners) for life. There is also a small but definite risk of blood clots causing stroke, even when taking anticoagulants.

Aortic valve repairs

Aortic valve repair is a new way of treating dysfunctional aortic valves. Not all leaking aortic valves are amenable to aortic valve repair and not all cardiac surgeons are capable in performing this type of operations. It is recommended that aortic valve repairs are performed by sub-specialist aortic surgeons with specialist interest in the field.

AV repair.techniques and mechanism

Tricuspid aortic valve (the aortic valve has three doors, normal configuration) that present with aortic regurgitation (leaking valves) can be treated using a number of different type of techniques with  very good record of success and excellent functional end-result.

      AV reapir 1      AV repair 2

Aortic valve repair can also be deployed into young patients with congenitally abnormal aortic valve (defects you are born with) like the bicuspid aortic valve (the aortic valve has two doors). The aortic valve repair of those valves can offer to the patient a functionally competent valve with excellent haemodynamics  and postpone the replacement therapy into the future.

BAV repair

Here are some procedures surgeons may use to repair your aortic valve:

  1. Commissurotomy, which is used for narrowed valves, where the cusps (the leaflets that make up the valve) are thickened and perhaps stuck together. The surgeon opens the valve by cutting the points where the cusps meet.
  2. Valvuloplasty, which strengthens the cusps to provide more support and to let the valve close tightly.
  3. Reshaping, where the surgeon cuts out a section of a cusp. Once the cusp is sewn back together, the valve can close properly.
  4. Decalcification, removes calcium which has built up on the cusps. Once the calcium is removed, the cusps can close properly.
  5. Patching, where the surgeon covers holes or tears in the cusps with a tissue patch.

Percutaneous options for aortic valve disease – TAVI or TAVR

TAVI1

Different TAVI valvesThis minimally invasive surgical procedure treats the malfunctioning valve and alleviates the symptoms without removing the old, damaged, native aortic valve. Instead, it wedges the new valve inside the old, diseased valve, which has been previously stretched open.

The surgery may be called a transcatheter aortic valve replacement (TAVR) or transcatheter aortic valve implantation (TAVI). These techniques are reserved for patients who are well over 70 years of age (usually in their 80s & 90s) and who either cannot have or who carry a very high risk of death from formal cardiac surgery. As a TAVI is still a new procedure, its long-term benefits are not known. At present, if you need to have an aortic valve replacement, it is more likely that you will be offered a conventional heart valve surgery.

tavi-steps

 The Oxford TAVI Team have been working together since the inception of the technology in 2009 and is delivering hundreds of TAVI operations per year.  Every case that is refereed for TAVI is discussed at our sub-specialised TAVI multidisciplinary team and the treatment options are individualized and optimized to meet the needs of each and every patient we treat.

When transcatheter aortic valve implantation (TAVI) is performed transfemorally, via the grointavi-transfemoral-oder-transapical, a local anesthetic is used to numb the area around the artery in order to insert a special catheter. Once inside the artery, the catheter is advanced from the groin to the aortic valve of the heart. This catheter carries an expanding valve armed with a specially designed balloon. After the new valve is implanted within the existing (native) valve, the patient returns to a high dependency area for observation. The patient usually leaves the hospital within 2-3 days after surgery.

When we are replacing the aortic valve through a small incision in the chest – transapically or transaortic, a general anesthetic is given to the patient. After a small incision has been made to the left side of the chest, a special catheter is advanced from the apex of the heart to the aortic valve. This catheter carries an expanding valve armed onto a special balloon. After the new valve is implanted within the native valve, the patient returns to a high dependency area for observation. The patient usually leaves the hospital within 3-5 days after surgery.

 

Videos

 

          
       Aortic valve problems

 

 

 

 

 

 

          

Aortic valve replacement     TAVI Implantation 

          

 

Links