Aortic valve replacement

Sustitución de válvula aórtica

Aortic valve surgeries allow patients to improve their quality of life. Each case is studied thoroughly in order to provide the best possible result.

 

Valvular heart disease can affect any of the four valves of the heart. Aortic valve disease is a condition in which the valve between the left ventricle and the main artery in the body (aorta) does not work properly. Aortic valve disease may sometimes be a condition present from birth (bicuspid aortic valve) or it may result from other causes. The most common valvular problem in old age is aortic valve disease..

 

The types of aortic valve disease include aortic stenosis and aortic regurgitation. In aortic stenosis, the aortic valve opening is narrowed. In the case of aortic regurgitation, the aortic valve does not close properly, causing blood to flow backward into the left ventricle.

 

To treat valvular disease, cardiac surgeons offer different possibilities:

 

  • Repairing the patient´s valve.
  • Replacing the valve:
    • Heterograft valve.
    • Mechanical valve.
    • Homograft valve.
    • Autograft (Ross procedure).
    • Sutureless valve.
Sustitución de válvula aórtica

Aortic valve surgeries allow patients to improve their quality of life. Each case is studied thoroughly in order to provide the best possible result.

 

Valvular heart disease can affect any of the four valves of the heart. Aortic valve disease is a condition in which the valve between the left ventricle and the main artery in the body (aorta) does not work properly. Aortic valve disease may sometimes be a condition present from birth (bicuspid aortic valve) or it may result from other causes. The most common valvular problem in old age is aortic valve disease..

 

The types of aortic valve disease include aortic stenosis and aortic regurgitation. In aortic stenosis, the aortic valve opening is narrowed. In the case of aortic regurgitation, the aortic valve does not close properly, causing blood to flow backward into the left ventricle.

 

To treat valvular disease, cardiac surgeons offer different possibilities:

 

  • Repairing the patient´s valve.
  • Replacing the valve:
    • Heterograft valve.
    • Mechanical valve.
    • Homograft valve.
    • Autograft (Ross procedure).
    • Sutureless valve.

The physician and patient will choose the type of valve, taking into account the patient’s overall condition and preference. Some of the patient factors considered are:

 

  • Age and life expectancy. The American College of Cardiology and American Medical Association guidelines indicate that mechanical valves are generally appropriate for the majority of patients who are 65 years old and younger, or patients already on a blood thinner treatment.
  • Other diseases. Lung, liver and kidney disease, diabetes, cancer and other chronic conditions can affect life expectancy and alter the age criterion.
  • Condition of the heart and vascular system. Coronary, carotid and peripheral artery diseases, and heart rhythm disturbances can affect valve selection.
  • Patient lifestyle and preference.

 

Valve Replacement

 

1. Heterograft valves:

 

Tissue valves are harvested from pig heart valves (porcine) or cow heart pericardium (bovine). These tissues are treated so that the body will not reject them. The lifetime of a tissue valve is typically 10 to 15 years, often less in younger patients. Over this time the valve will be likely to degenerate to the point of requiring replacement. Because of this possibility, patient life expectancy is a major criterion in considering a tissue valve. The primary advantage of tissue valves is their lower requirement for anticoagulation therapy, which reduces the incidence of bleeding. For the majority of tissue valve patients, taking an aspirin a day is sufficient anticoagulation therapy.

 

2. Mechanical Valves:

 

The most widely used mechanical valves are made of pyrolytic carbon, which has been used for over 30 years. Most are bileaflet designs, meaning that they employ two carbon leaflets to regulate flow in a single direction. The primary advantage of mechanical valves is that they will last a patient’s lifetime. Mechanical valves are preferred for patients with life expectancies beyond 10–15 years because they eliminate the mortality risk inherent in the replacement of a degenerate tissue valve. The best mechanical valves have excellent flow performance, including the smaller ones. The main drawback of mechanical valves has been their requirement for Warfarin anticoagulation therapy (blood thinner), with its accompanying risk of bleeding. With properly managed anticoagulation therapy, both bleeding and clotting rates are low. Mechanical valves can sometimes be audible when they open and close. The sound level varies from patient to patient, but only a small number of patients find the sound disturbing.

 

3. Homograft Valves:

 

In some cases, a homograft – a human aortic valve – can be implanted. Homograft valves are donated by people and recovered after the person dies. The durability of homograft valves is comparable to porcine and bovine tissue valves. The principal indication for aortic valve replacement using a homograft aortic valve is for active aortic valve endocarditis (native or prosthetic) with or without perivalvular tissue destruction (abscess cavity, fistula, etc.). Since the homograft tissue is pliable and adaptable, it can be used to repair defects in complex cases with root destruction.

 

4. Autograft (Ross Procedure):

 

In the Ross procedure, the diseased aortic valve is removed and replaced with the patient’s own pulmonary valve (autograft). After the pulmonary valve has been transferred to the aortic position, a pulmonary homograft from a donor (human cadaver) valve is sewn into the pulmonary position, and the coronary arteries are re-implanted. The longevity of the pulmonary autograft in the aortic position is superior to bioprostheses and, therefore, the Ross procedure is particularly appropriate for children and young adults with diseased aortic valves. The pulmonary valve has the potential to grow as the child grows (which artificial valves cannot do), and it is well suited to the high pressure in the aorta. The procedure is also a good option for women who wish to become pregnant and for active patients who do not wish to take anticoagulants.

 

5. “Sutureless”aortic valves:

 

The concept is a prosthetic valve comprising a bovine pericardium tissue valve attached to a self-expandable anchoring device, which has the dual role of supporting the valve and providing fixation to the implantation site. Sutureless biological valves were designed to simplify and significantly accelerate the surgical replacement of a diseased valve and first require the complete excision of the calcified native valve. Shortening the time required for aortic valve replacement may help to reduce morbidity and mortality, especially in patients who require complex multivalve or combined valve and coronary procedures. Transcatheter aortic valve implantations (TAVI) may eliminate the need for open heart surgery in select groups of patients. In the USA, has been an FDA-approved percutaneously implantable aortic valve system for high surgical risk and inoperable patients with symptomatic aortic stenosis with other catheter-based devices on trial use since October 2012.

Sustitución de válvula aórtica 2
Sustitución de válvula aórtica 2

Cuando tenemos que sustituir la válvula enferma del paciente, tenemos varias posibilidades:

 

  • Prótesis Mecánicas: están fabricadas de un material llamado carbón pirolítico (grafito purificado) que es duro como el diamante y muy poco trombogénico (baja probabilidad de producir trombos o embolias). Aunque, en principio, no se rompen ni degeneran nunca, su desventaja es que es imprescindible tomar diariamente, y de forma indefinida, anticoagulantes orales (Sintrom®).
  • Prótesis biológicas: están hechas de tejido animal o humano. No precisan tomar anticoagulantes orales como el Sintrom, pero su principal inconveniente es que degeneran con el tiempo y tienen una duración limitada a 10-12 años. Después de ese tiempo tienen que ser reemplazadas. Se recomiendan en pacientes que no pueden o no quieren tomar anticoagulantes, en pacientes ancianos y en mujeres que quieren tener hijos.
  • Otros sustitutos valvulares biológicos: En este grupo podemos incluir los homoinjertos de cadáver criopreservados (válvulas de donante humano) y la Operación de Ross, que utiliza la propia válvula pulmonar del paciente para sustituir la válvula aórtica enferma.

 

En la actualidad, ante el gran aumento de los pacientes de edad muy avanzada y con riesgo quirúrgico muy alto, se han desarrollado dos nuevas modalidades de prótesis aórticas: La prótesis aórtica sin sutura (“sutureless”) que permiten realizar la intervención mucho más rápido, con menor agresión y por incisiones reducidas, y las prótesis aórticas transcatéter que no precisan cirugía y que pueden implantarse por vía percutánea (a través de la arteria femoral de la pierna).

 

Cada modalidad de tratamiento tiene sus ventajas y desventajas, y debe elegirse la mejor opción para cada paciente de forma individualizada.