Andersons pediatric cardiology 913

Aortic, pulmonary, and mitral homografts are today no longer used because of their poor durability.. Complications Historically, the postoperative results were poor, especially for patie

homograft There is certainly a potential for growth of the pulmonary autograft However, this advantage is often lost for the pediatric population because the technique requires the insertion of the autograft in a synthetic conduit for its stabilization (“top hat procedure”)102,103 and also for the build-up of a tight circular fibrous deposit around the intra-atrial portion of the latter conduit

Aortic, pulmonary, and mitral homografts are today no longer used because of their poor durability

Complications

Historically, the postoperative results were poor, especially for patients younger than 2 years The early mortality rate was 20% in most reports and can

potentially double in patients younger than 2 years.33,94,104–106 A complete heart block occurs in around 15% of patients, requiring insertion of a permanent pacemaker.33,94,107 Detailed analysis demonstrated that the risk of death is

associated with the insertion of an oversized prosthesis Placement of an

adequately sized prosthesis in an intraannular position does not carry this

associated mortality probability (Fig 34.42).33

FIG 34.42 Mitral valve protheses and their z-scores to evaluate their size

relative to the normal mitral valve annulus size for the recipient's body surface area at the time of implantation Patients receiving a prosthesis

matching exactly the normal annular size have a probability of survival at 1

year of 100% (From Caldarone CA, Raghuveer G, Hills CB, et al Long-term survival after mitral valve replacement in children aged <5 years: a

multi-institutional study Circulation 2001;104[12 suppl 1]:I143–I147.)

The risks of thrombosis of a mechanical valve, bleeding and endocarditis are reasonable (usually less than 10%) but their consequences are not negligible

Risk Factors and Long-Term Results

Studies are heterogeneous, describing results of mitral valve replacement in populations of various sizes and different ages However, a young age (<2 years) and an increased prosthesis size/patient weight ratio are the usual identified risk factors for mortality.105–110

The freedom from reoperation is generally not lower than 90% at 5 years The survival rates at 10 years vary from 60% to 90% In a long-term study, Brown et

al reported a freedom from reoperation and a survival rate of 63% and 71%, respectively, at 35 years.107

De Lange FJ, Moorman AFM, Anderson RH, et al Lineage and morphogenetic analysis of the

cardiac valves Circ Res 2004;95(6):645–654.

An embryologic study that significantly contributed

to the description of the mitral valve's morphogenesis.

Shone JD, Sellers RD, Anderson RC, et al The developmental complex of “parachute mitral valve,” supravalvar ring of left atrium, subaortic

stenosis, and coarctation of aorta Am J Cardiol.

1963;11:714–725.

Shone and colleagues’ original report of the

multileveled obstruction of the left heart The association of the four items is often incomplete Coarctation of the aorta can be the only

anomaly present at birth and the mitral valve disease may not be present initially.

Nishimura RA, Otto CM, Bonow RO, et al 2014 AHA/ACC guideline for the management of patients with valvar heart disease: a report of the American College of Cardiology/American

Heart Association task force on practice

guidelines J Am Coll Cardiol 2014;63(22):e57–

e185.