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A heart-to-heart
For mitral valve disorders: Should we repair or replace?
by Divyakant B. Gandhi, MD FACS FRCS
The heart is a biological pump that performs
a mechanical function in the body; and like any other pump, the heart needs
valves to direct the flow of fluid—in this case blood—in order
for it to function effectively and efficiently. Anatomically, the heart has
four chambers. Two atria at the top collect the blood, and the two ventricles
at the bottom of the heart pump the blood.
There are two valves on the right side of the heart, the tricuspid valve between
the right atrium and the right ventricle and the pulmonary valve between the
right ventricle and pulmonary artery, which is the main blood vessel to the
lungs. The left side of the heart has the mitral valve between the left atrium
and the left ventricle and the aortic valve between the left ventricle and
the aorta, the main blood vessel of the body.
Both the aortic and pulmonary valves are simple valves, much like the valve
of an engine allowing the flow of fluid, unimpeded in one direction only. On
the other hand, the mitral valve, and to much less extent the tricuspid valve,
are much more complex and are intimately involved in the integrative function
of the ventricles. Because of this relationship, any dysfunction of the mitral
valve affects the efficiency of the heart much more significantly.
The most common disorder affecting the mitral valve in third-world countries
is a narrowing of the mitral valve secondary to rheumatic fever. In the United
States, however, mitral valve prolapse, secondary to myxomatous degeneration
(overgrowth and dilation of primitive tissue) is the most common disorder,
and results in a leaky mitral valve. Not all patients with mitral valve prolapse
need surgical treatment unless there is significant regurgitation (backward
flow or leaky mitral valve) with accompanying symptoms.
Some typical symptoms that one may experience with mitral regurgitation are
shortness of breath, especially with exertion or exercise; awakening in the
middle of night with shortness of breath and swelling of the ankles.
To compensate for the leaky mitral valve, the body tends to retain water. That
retained water, during the daytime, gravitates toward the feet, consequently
causing swelling of the ankles with patients complaining of “shoes feeling
tight in the evening.”
At night, when the patient is lying flat in bed,
the same fluid relocates to the bloodstream and fills the lungs, resulting
in shortness of breath to the extent that the patient has to wake up and
sit up, preferably near an open window to relieve his or her symptom.
This is typically called paroxysmal nocturnal dyspnea. Some other symptoms
associated with this condition are fatigue, tiredness and lack of energy.
For the longest time, the treatment of a leaky mitral valve was replacement
with an artificial mechanical or tissue valve. However, this method of
treatment causes a disruption of the coordinated efficient function of
the left ventricle,
resulting in poor long-term prognosis of patients.
Consequently, most patients with mitral valve regurgitation were treated
with medications until the dysfunction became so significant that patients
developed
and remained in congestive heart failure.
This long-term treatment with medications alone resulted in significant
and irreversible enlargement and dilation of the left ventricle to the
extent
that replacement of the valve, at that point, did not necessarily result
in favorable
outcomes.
In France during the 1970s, Professor Alain Carpentier developed procedures
to repair the mitral valve, thus preserving the intimate correlation between
the function of the mitral valve and function of the left ventricle.
These techniques have been further refined, but took a long time to gain
acceptance in this country. Presently, however, mitral valve repair is
the procedure of
choice for treating disorders of the mitral valve.
A large variety of techniques have been described and developed to repair
the mitral valve.
These include placement of a geometric ring around the rim of the mitral
valve; removal of excess and damaged tissue and reconstruction of the valve;
translocation
of chordae (structures that connect the leaflets of the valve to the muscle
mass of the left ventricle) to reinforce weak areas of the valve; shortening
of dilated chordae; replacement of broken chordae with artificial sutures;
replacement of damaged leaflets with artificial biological tissue, etc.
Studies of patients who have had mitral valve repair indicate that they
do much better than patients who have had mitral valve replacement in terms
of short and long-term survival and in terms of improvement of their symptoms
primarily because it maintains the extremely important integrative relationship
between the mitral valve and the left ventricle.
This emphasizes the fact that your God-given valve is far better than any
artificial valve developed by humans and, therefore, it is incumbent upon
cardiac surgeons
to preserve that valve as much as possible. Recent data has also indicated
that if the mitral valve could be repaired, it should be done earlier in
the course of the disease process before irreversible damage occurs to
the ventricle.
In our previous article, we talked about atrial fibrillation and its surgical
treatment. It is important to recognize that a large number of patients
with mitral valve disease have concomitant atrial fibrillation and may
require
surgical treatment of atrial fibrillation at the time of surgery for the
mitral valve
disorder.
The treatment of mitral valve disease is complex and requires careful consideration
since it affects the lives of patients before and after surgery.
Therefore, before a physician refers a patient to a heart surgeon for surgery
on the mitral valve, he or she should carefully evaluate the experience
and the expertise of that particular surgeon in repairing the mitral valve.
At Ingham Regional Medical Center I, along with the help of our cardiovascular
team, provide the expertise to repair the mitral valve in a large majority
of patients. Hence, our goal is to help patients have a better quality
of life!
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