Heart Conditions

December 14, 2007

Mitral Valve Prolapse and other Valvular Abnormalities

Mitral Valve Prolapse (MVP) is so common that many are beginning to think of it as a normal variation.  The reason it gets so much attention is because, as benign as it is, it still causes symptoms that are very disturbing. The heart is an amazing organ, synchronizing the entrance and then ejection through two different systems, depending on whether the blood is oxygen-rich or oxygen-depleted.  It has four chambers, and the blood in each chamber is separated from the other chambers by a trap door effect of valves that slam shut then open repeatedly with each stroke of the heart.  If there's damage to the valves, then blood can leak forward or be forced backwards.

This is a much different arrangement from the circulation of the fetus.  See Fetal Circulation.

The mitral valve sits between the left atrium and the left ventricle.  Oxygenated blood from the lungs flows into the left atrium, then passes via the mitral valve gatekeeper to the left ventricle in preparation for the burst of propulsion to the aorta.  In MVP, the valve is weakened by causes unknown, and flaps backwards into the left atrium during the ejection of blood from the left ventricle.  Although MVP is associated with many serious heart defects, it is usually a benign condition that merely provokes disturbingly weird symptoms.

Palpitations, then anxiety (either because of the palpitations or along with them), shortness of breath, unusual chest pains, and panic attacks are famously associated with MVP.  It is difficult to separate the anxiety with as opposed to the anxiety because of the palpitations and chest pain, but the cluster is certainly a legitimately recognized symptom complex attributed to MVP.  It's no fun to suffer from symptomatic MVP.  In addition to the above discomforts, there are also the psychodynamics of being blown off as an hysteric.  Anger, embarrassment, and the added expense of rotating doctors only make life worse.

It might be expected to be worse in pregnancy, since the increase in blood and plasma and the changes in cardiac activity that are normal in pregnancy should challenge the valvular system more than usual.  But actually MVP improves in pregnancy in most women, because the physical changes in the heart tend to realign the mitral valve components into a more normal position.

With most pregnant women who have MVP being symptom-free, the biggest concern is whether to treat them with antibiotics at delivery as would be done with patients with other valve damage.  Dentists often treat MVP patients with antibiotics before dental procedures, so patients may expect them at the time of delivery.  But the current thinking is to forego any antibiotics unless there are abnormalities of heart function along with the MVP or complicated deliveries.  Uncomplicated vaginal or Cesarean deliveries don't necessarily need the antibiotics for just the MVP.

In summary, Mitral Valve Prolapse for the most part poses no challenge in pregnancy, and its symptoms are even seen to improve.  In fact, if there are troubling symptoms one should suspect another cardiac condition that may have not been challenged enough to be obvious before pregnancy.

Pregnancy Heart Problems: The rest of the story...

Before discussing other heart problems that might impact pregnancy, we need to take a  trip through the heart, starting at the beginning:

After oxygen-rich blood has dumped its fuel into the tissue needing it for our moment-to-moment actions and consciousness itself, it is returned by the smaller veins of the body into larger and larger veins, ultimately returning to the heart by the biggest veinshe inferior and superior vena cavae.  These dump into the right atrium (RA) of the heart, and with the next "beat" of the heart this muscular chamber squeezes it on through the opening into the right ventricle (RV), that opening surrounded by the tricuspid valve which under ideal circumstances won't allow retrograde backflow back into the atriumhis valve slams shut after the blood delivered to the RV builds up enough pressure to slam shut it's leaflets (three "cusps," hence its name, tricuspid valve).

From the right ventricle, the next beat of the heart forces this blood past its own exit valvehe pulmonary valve (PV) into the arteries that will deliver this oxygen-poor blood to the lungs for re-oxygenation. The next beat of the heart which propels blood from the left atrium (LA) to the left ventricle (LV) creates a vacuum that sucks now the newly oxygen-rich blood from the pulmonary area into this negative pressure chamber (LA).  With the next beat, the same thing happens on the left side that happened initially on the right, the left atrial blood is pumped past the mitral valve into the left ventricle.  And it all happens simultaneously.

  The story so far:
Used up oxygen-poor blood returns to right atrium, pumps past the tricuspid valve to the right ventricle, exits the right ventricle through the pulmonary valve to the lungs, returns oxygenated from the lungs into the other side of the heart, the left atrium, then gets pumped past the mitral valve to the left ventricle, the star of the show.

The Left Ventricle

        The star of the show is the left ventricle because it must have the contractile strength to eject its contents back out to the rest of the body where oxygen is needed.  Blood is pumped past the last valve of the heart, the aortic valve, into the aorta.  The whole process is a single file arrangement, each emptying chamber being refilled with the blood of the chamber before it, with the lungs sitting between the right-sided chambers and the left-sided chambers.  And as blood whooshes (obscure medical term) is way to the next chamber, the process effects refilling from the previous chamber.

 


De-oxygenated
blood from the 
rest of the body
into 
RIGHT 
ATRIUM
through

LUNGS

into 
LEFT
ATRIUM
through
as 
Oxygenated
blood back 
out to all 
of the body
  tricuspid valve  mitral valve
into
RIGHT 
VENTRICLE
through
into
LEFT 
VENTRICLE
through
 
 pulmonic valve
to
 aortic valve
out of the heart
If you follow the direction just through the valves, it's
tricuspid valve  ? pulmonic valve ? LUNGS ? mitral valve ? aortic valve ?
REST OF THE BODY.


(But armed with this knowledge, you ain't no cardiologist yet!)

        Just as there are failings of the mitral valve as described above, so there can also be problems with the other valves.  Below I discuss such inadequacies only as they pertain to pregnancy.  But no discussion of pregnancy complicated by heart valve disease should be presented without an introduction that discusses the main cause of it all: Rheumatic Heart Disease, presented in the right pane below*:
 

       Initially, the Mitral Valve was discussed as a discussion of the benign disorder of MVP.  Abnormalities of three other valves, as well as some other points about the Mitral Valve, are now addressedn order of the trip around the heart.

The Tricuspid Valve

        This is the valve that blood from the right atrium passes through to get to the right ventricle before going on to the lungs for oxygenation.  Regurgitation is a cardiologist's term for leak-back into the previous chamber, in the case of the tricuspid valve, right ventricular blood backing up into the right atrium that fed it.  Since the right ventricle is the chamber that pumps blood to the lungs, severe tricuspid regurgitation reduces the volume of blood going to the lungs. Less blood gets oxygenated and the patient may suffer from cyanosis (turning blue).  This is called cyanotic cardiac disease.
        It's a bad thing to have.
        Usually, though, it's related to a cluster of cardiac problems a woman was born with.  Holes in the heart between the right side and the left side mixes up oxygen-poor blood and oxygen-rich blood in these patients, and the tricuspid regurgitation only adds to the decrease in oxygenation that they need.
        The risk to the infant is secondary to the compromise of the woman.  If she's blue, then the baby's not getting his or her right oxygen either. Prematurity and stillbirth add to the risk of defects from all of the medicines these women are already on.

The Pulmonary Valve

        This is the valve next in line after the tricuspid valve.  It lets the blood out of the right ventricle on the way to the lungs.  Disease of the pulmonary valve presents as either stenosis (stiffening, scarring) resulting in obstruction of the normal flow to the lungs, or as insufficiency, resulting in regurgitation back into the right ventricle.  The stenosis may back things up to the point where the pregnant woman begins to have tricuspid regurgitation (see above); the insufficiency could result in enlargement of the right ventricle, which can throw the whole heart function off if severe enough. 
        Usually pregnancy is well tolerated with pulmonary valve disease if exercise before pregnancy is well tolerated.

*Rheumatic Heart Disease

        It all starts with a "strep throat," that is, an infection with the Streptococcus A bacterium.  The most common age group vulnerable to the whole spectrum of this disease is 5 - 15.   After a strep throat, anytime in the next six weeks symptoms develop which include:

?nbsp;      swollen, tender, painful joints, possibly associated with nodules ("Rheumatic nodules") over these joints
?nbsp;      a raised rash over the abdomen and chest and back
?nbsp;      fever
?nbsp;      shortness of breath
?nbsp;      weakness or shakiness ("chorea")

        The final result is damage to the connective tissue of the heart, mainly the heart valves.
        What's happening is that there seems to be an immunity reaction to either the bacteria themselves or to the products of these bacteria (foreign protein).  In any event, heart valves and other connective tissue, even the pacing tissue of the heart, are accidental victims of the body's immunologic response to the strepuch like innocent bystanders in a drive-by shooting.  Repeated strep infections can further damage the heart structures.
        Because it is felt that some individuals never really lose the strep infection, people with a history of Rheumatic Fever are maintained on life-long antibiotics.  Also, antibiotics before any surgical procedure that may remount the immune response are prescribed, as in dental procedures or other surgeries.  (IUDs are a bad choice of contraception for these women).
        A scary aspect of both strep throat ("pharyngitis") and the ensuing Rheumatic Fever is that often the symptoms can be so mild that either one of them can go unnoticed!  For this reason, even the slightest sore throat in a child should be evaluated.


In a nutshell: 
Strep throat --> Rheumatic Fever ? Rheumatic Heart
Disease

The Mitral Valve

        The initial part of this article discusses mitral valve prolapse (MVP) and its usually benign ramifications.  True disease of the mitral valve, which sits between the left atrium and left ventricle, will truly alter the function of the left side of the heart.

        Rheumatic heart disease can create damage to the mitral valve. A patient with a history of rheumatic heart disease is always at risk to the damage progressing, so antibiotics are prescribed with any surgical or dental procedure to prevent further damage.

MVP is not rheumatic heart disease. 

    As mentioned in the first section, no one knows the cause of MVP.  But real damage to the mitral valve from rheumatic disease can seriously threaten a pregnant woman and her baby.
        As with any malfunctioning valve, stenosis can cause an obstructive problem, and insufficiency a regurgitation problem.  The most frequent problem is mitral stenosis, which causes resistence to the push of blood onward.  Everything backwards to the lungs can be overloaded, causing pulmonary hypertension.  The tricuspid valve can be damaged, and the regurgitation due to its failings can cause right heart failure.
        In pregnancy, with its associated increase in blood volume and heart rate, the increase in pressure on the left side of the heart, already pounding against a scarred mitral valve, can make pulmonary hypertension behind it even worse.  For this reason, 25% of women who otherwise deal with their disease well when non-pregnant will have symptoms that include trouble breathing in the second trimester, and then becoming worse during labor and delivery.  Since all of this mucking up of the works can cause blood clots, many women with mitral stenosis have to be on anticoagulants ("blood thinners").  Antibiotics are prescribed generously as well, especially with any procedure, since mitral stenosis is usually a problem of scarring after repeated damage to the valve from rheumatic carditis.
        Pulmonary edema (fluid in the lungs), atrial fibrillation (life threatening arrhythmia), hypotension (low blood pressure), and repeated endocarditis (re-infection of the abnormal mitral valve) are very frightening problems with this disease.
        Any woman with mitral stenosis should be followed by a perinatologist in close association with her cardiologist.  This is a very severe complication of pregnancy.

        On the other hand...
        Mitral regurgitation, or leaking back of blood into the left atrium, is usually well tolerated in pregnancy.  It's not usually due to rheumatic heart disease, but has many causes.  There are usually no fetal effects from this valvular insufficiency.

The Aortic Valve

        Once again, it's a matter of either too stiff (stenosis) with obstruction of flow, or too loose (insufficiency) with regurgitation
backwards.  Rheumatic disease is the culprit.
       Of these two, aortic insufficiency is the more common.  It is usually well tolerated in pregnancy, and if so, is not harmful to the unborn baby.
        Aortic stenosis of a mild to moderate degree is usually well tolerated in pregnancy, and severe disease is usually not likely while women are of childbearing age.  But if it is severe and a woman is pregnant, the biggest problem seems to be the inability to compensate for exertion, since the obstructive nature of the valve tends to limit the amount of output from the heart to the rest of the body.  With this decrease in output, if the amount of blood coming into heart is decreased as well, there could be a big drop-off in blood supply to the mother's brain or the baby's placenta.  Just the weight of the baby and enlarged uterus on
the vena cava, the main vein that sends blood back up to the heart, can cause just such a disaster.  Just the normal blood loss expected at the time of delivery can do likewise.
        Maternal and fetal death are real concerns with severe aortic stenosis in pregnancy!  This condition is so harrowing in pregnancy that childbearing-age women who have severe aortic stenosis should have surgical correction of this valve before attempting pregnancy.

Once again, since rheumatic endocarditis can recur after any procedure, an IUD is a bad choice of contraception.  It is a foreign body that will present to the body as a sort of continuing procedure.

        Another problem with Rheumatic Heart Disease patients who are pregnant comes up if there's pre-term labor.  Many of the medicines we use to stop premature labor have impact on the function of the heart.  Even simple hydration can cause fluid shifts that will affect the success of treatment.  Brethine and Procardia, used to relax the uterus, can cause a racy heart or decreased blood pressure, mildly annoying in some conditions, but absolutely contra-indicated in others.
        So besides the pregnancy's impact on heart disease and the heart disease's impact on the pregnancy, we must also be aware of the effects on pregnancy and heart disease by the treatment of complications of either.

©2000 Gerard M. DiLeo, M.D.
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