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What your doctor said about…..
Mitral Regurgitation
How does the heart work?
The heart is a pump. A muscle pump. It is the size of your fist, and sits in the middle of
your chest. It is actually a double pump, one side taking venous blood from your head
and your feet, and pumping it onwards to the lungs. In the lungs, blood is enriched with
oxygen, and turns bright red. It returns to the left side of the heart, and is pumped
onwards to nourish the body. The direction of blood flow is controlled by 4 valves.
Within the muscle of the heart is an electrical system. A master spark plug at the top of
the heart gives out an electrical signal, which travels to a junction box. From here, the
signal moves downwards to the heart muscle and – like a cattle prod – elicits contraction
of heart muscle. The heart empties (into the lungs, and the body), and in relaxation, fills
again.
What is ‘mitral regurgitation’?
The mitral valve is on the left side of the heart, controlling the flow of blood from the left
atrium to the ventricle. It has 3 leaflets that open towards the pump, and meet one
another when the valve is closed. In fact, the mitral valve gets its name from a bishop’s
miter (3 cornered hat). Think of the left atrium as a priming chamber, getting blood
ready for the main pump. When this chamber contracts, the mitral valve opens. Blood
rushes through and fills the left ventricle. The mitral valve then closes, the ventricle
contracts, and blood is ejected through another valve (the aortic valve), out to the body.
In mitral regurgitation (leak of the valve), the guy wires that anchor the leaflets of the
mitral valve are overstretched, loose, or broken – or the leaflets themselves may be
damaged. As a result, the leaflets cannot meet properly, and some blood returns to the
left atrium when the ventricle contracts. This ‘regurgitation’ means that, with the next
heartbeat, the overfilled left atrium, and has to empty more than its usual quota of blood.
Of course, it does so.
What causes mitral regurgitation?
It used to be a common consequence of childhood rheumatic (or scarlet) fever –
fortunately rare these days. Longstanding hypertension (high blood pressure) and
advancing age are more common causes now. Other causes include infection of the
valve (endocarditis), or a dilated heart (cardiomyopathy). It is quite common to have a
mild form of this condition; studies suggest 10% of the elderly have it.
What symptoms does it cause?
Initially, NONE. As the degree of backleak, or regurgitation, progresses from mild to
moderate to severe, blood returning to the lungs meets up with an already full left atrium
unhappy with accepting more. Symptoms, such as shortness of breath with activity, or
fatigue can occur. If the volume of blood in the left atrium causes this chamber to
stretch, the electrics of the heart are affected, and palpitations or atrial fibrillation can
develop. (In fact, it is not uncommon for these symptoms to bring to your attention the
fact that you have an underlying valve problem). Symptoms can take years or decades to
develop.
What can be done to prevent worsening of mitral regurgitation?
You can take the strain off the mitral valve, and its ‘guy wires’, by lowering the pressure
in the heart. Essentially, this means lowering blood pressure. Whatever blood pressure
you have now, you need less. For example, if you have moderately severe mitral
regurgitation and your blood pressure is 150/80, maybe you should aim for 110-120/70.
This can be done with blood pressure medications, like HYDROCHLOROTHIAZIDE,
ALTACE, DIOVAN, ATACAND, etc.
Can the valve ever improve?
Yes. Some people have MR due to a large (and weak) heart. As we reduce the size of
the heart, and take the strain off by lowering blood pressure, the ‘guy wires’ can resume
their normal tension, and the valve may work properly again.
Is surgery an option?
Yes. Surgery (mitral valve repair or replacement), is usually reserved for those with
severe MR causing breathlessness at low or moderate levels of activity, and have not
done well with drug therapy. It is a big operation, but not uncommonly done is patients
in their 60s, 70s and even 80s.
What about palpitations? What should I know about these?
‘Palpitations’ is the name given to an awareness of you heartbeat, either skips or runs of
extra beats. You may even feel your pulse ‘miss a beat’. In general, they are of no
consequence. They don’t damage your heart, or shorten your life. However, if they are
fast and frequent, they can make you tired and breathless, and need treatment. Atrial
fibrillation is the name given to a common ‘rhythm problem’ associated with mitral
regurgitation and stretch of the left atrium. This rhythm is rapid and irregular, and often
fast enough to make one anxious and weak. It can be slowed down with medications
(DIGOXIN, VERAPAMIL, DILTIAZEM, METOPROLOL, and others) and sometimes
corrected with drugs or an electrical signal. Atrial fibrillation that is constant carries
with it a small risk of clot formation in the left atrium, which can be the cause of stroke if
it breaks off. For this reason, patients with AF are offered anticoagulant therapy
(COUMADIN) to avoid this consequence. Discuss this further with your doctor.
Anything else I should know about mitral regurgitation?
Yes. If you have had an infection of the mitral valve, or if you have an artificial mitral
valve, we encourage you to take an antibiotic when you have dental cleaning, or certain
types of surgery. Infection of a heart valve is definitely not a good thing. It further
damages the valve, resists treatment, and requires prolonged and intensive intravenous
course of antibiotics – even surgery. So if you have a prolonged fever on top of a
damaged or artificial valve (endocarditis), it might not be the ‘flu, but something worse..
How do you follow-up patients with MR?
Th most accurate way to look at a heart valve is through ultrasound (or ECHO). This
can be done every year or so, depending on your symptoms. They are done in the
radiology department, and take about 40 minutes to complete.
For further information, check out the following websites:
http://www.aboutatrialfibrillation.com
http://www.americanheart.org
http://www.health-heart.org
http://www.heartinfo.org
HMB –Mitral Regurgitation: May 2010