Valvular
heart problems involve primarily narrowing (stenosis)
or leakage (insufficiency or regurgitation)
of the aortic valve (primary outlet valve of the heart)
or mitral valve (primary valve between the upper and
lower chambers of the heart). All blood pumped by the heart
passes through these valves. Problems can be caused by rheumatic
fever or simply by degenerative changes occurring over many
years of opening and closing every second of the day. Certain
systemic illness and disease can contribute to the development
of valve problems including auto immune disease such as arthritis,
infections and kidney failure.
A congenital defect in which the aortic valve has
only two leaflets instead of three is one of the most common
causes of aortic valve narrowing.
Aortic valve disease of a degree that requires surgical
intervention usually requires replacement of the valve although
repair is possible depending on the specific anatomic situation
and the experience of the surgeon. The most important decision
facing a patient who requires aortic valve replacement
is the type of valve to use. The decision can only be made
after a thorough, open and honest discussion with a surgeon
experienced with all types of valve devices.
Valves used for replacement are of two basic types: tissue
and mechanical. Mechanical valves are constructed
entirely of man made materials usually pyrolite carbon, a
diamond hard material attached to a Dacron sewing ring to
attach it to the patient's tissue. Current mechanical valves
are usually of a tilting disk one way flow design and have
the advantage that they do not wear out. Mechanical valves
do, however, require lifelong treatment with Coumadin, a blood
thinner that can cause increased susceptibility to bleeding
particularly in older patients.
Tissue valves include several types all of which have
the advantage of not requiring Coumadin but only long term
treatment with a platelet inhibitor blood thinner such as
enteric coated baby aspirin which has few side effects. All
tissue valves have the disadvantage that they may
wear out with time and require further valve surgery. However,
with current advances in valve preparation and preservation
techniques, one can expect an 85-90% chance that a tissue
valve will remain functional after 15-20 years. These
valves are most appropriate for patients over 50-60 years
of age and are constructed from either bovine (cow) pericardium
or porcine (pig) heart tissue. In younger more physically
active patients, homograft valves (cryopreserved (deep
frozen) human cadaver valves) may be appropriate because of
their favorable hemodynamic characteristics but they require
a more extensive operation and may wear out with time.
Another valve option suitable primarily for younger patients
and children is the so called Ross switch procedure which
consists of transferring the patient’s pulmonary valve
to replace the diseased aortic valve. The pulmonary valve
must then be replaced with a cryopreserved human cadaver
valve. This procedure offers an excellent hemodynamic
result, but is a much more extensive procedure technically,
has a higher operative mortality and leaves the patient with
two tissue valves that will eventually wear out rather than
just one. Nonetheless, it is appropriate to use in specialized
cases.
Dr. Ott has the advantage of having extensive experience
in valve surgery of all types and will thoroughly discuss
the risks and benefits of each in an honest and unbiased fashion
based on the individual patient’s data, needs and wishes.