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Mitral Valve Repair/Cardiomyopathy??
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Mitral Valve Repair/Cardiomyopathy??


  I have seen mention on this forum and other places about the importance
  of performing mitral valve repair at the correct time to avoid "irreversible
   damage" to the left ventricle.  I had a successful repair of a 4+
  regurgitation due to flail leaflet and ruptured chordae earlier this year.
  I have no idea how long the MR was present since I was not aware of any
  problem at all until development of CHF symptoms took me to a doctor. Prior to
  the operation my EF was 70%; a month afterwards it was 30% (valve works fine).
  What causes this to happen and does it have a name when caused by a valve?
  How often does such a large EF difference occur after MV repair?
  Does the enlargement and hypertrophy ever resolve over time?
  My doctor mentioned "scarring" when I asked what was broken.  What
  causes scarring? How does one know this?
  Where can I learn more about what is actually wrong (i.e., is there a
  "Heart Physiology for Dummies" book?) I have looked on the Internet and
  browsed through some textbooks but haven't found any information
  pertaining to mitral valve problems causing CM.
  Are antibiotics required for dental work for patients with a repaired
  valve and annuloplasty ring?
  Thanks for your time!
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Dear Katie, thank you for your question.  After explaining the process of mitral regurgitation (MR), I'll address each of your questions.  The mitral valve separates the left atrium and left ventricle and is composed of two leaflets.  MR is caused by degeneration of the valve leaflets (could also be called scarring) and stretching of the valve supporting structures (chordae tendinae).  The two valve leaflets then do not close properly so blood leaks back through the mitral valve rather than leaving the left ventricle through the aortic valve.  When one of the chordae ruptures, the leaflet it's supporting is left to "flail" in the permanently open position.  MR is almost always severe when there is a flail leaflet.  With MR, the left ventricle compensates by becoming hypercontractile to deal with the increased blood volume it's exposed to.  The blood that leaks into the left atrium through an incompetent mitral valve returns to the left ventricle with each successive cardiac cycle so the blood volume the left ventricle is exposed to gradually increases.  The ejection fraction (EF) measures how much blood is ejected with each beat from the left ventricle and is normally > 55%.  With MR, blood is ejected through the normal pathway into the aorta and into the left atrium (wrong direction) so the net amount of blood that leaves the left ventricle with each heartbeat may be even higher than 55%.  But, this measurement is an artifact since a good portion of the blood is going in the wrong direction.  To compensate for the increased volume, the left ventricular muscle hypertrophies (increases in size) but eventually, the LV can no longer compensate and it begins to dilate.  When the mitral valve is repaired (or replaced), there is no longer increased volume in the LV and the blood can only go in the "right" direction.  Since the LV may have dilated and its muscle may have weakened, the EF may drop precipitously but it must be remembered that the value with severe MR is higher than it really is.  The LV usually recovers with time, but it may take up to one year for the EF to normalize.  Another point about the EF; it is a relative measurement that is subject to error each time it's measured, so the range of the EF values, and not an individual value, is most important.  Antibiotics should be given to all patients with MR or with a mitral valve repair and annuloplasty ring before dental procedures and all other invasive procedures.  Thus, I hope I've addressed all of your questions.  For more information, I've listed a medical journal article below and a chapter in a cardiology textbook that are the only resources I could find.  These references can be found in any medical library.  I couldn't find any specific references for the "general public."  
Information provided in the heart forum is for general purposes only.  Specific diagnoses and therapies can only be provided by your physician.
Mitral Valve Disease by Joseph S. Alpert, Joseph Sabik, and Delos M. Cosgrove III in
Textbook of Cardiovascular Medicine.  Editor: Eric J. Topol , 1998, Lippincott and Raven
Unique Identifier
97309176
Authors
Reul RM.  Cohn LH.
Institution
Surgery Department, Harvard Medical School, Boston, MA, USA.
Title
Mitral valve reconstruction for mitral insufficiency. [Review] [263 refs]
Source
Progress in Cardiovascular Diseases.  39(6):567-99, 1997 May-Jun.
Abstract
Mitral valve reconstruction is now the procedure of choice for many mitral regurgitant lesions. Early enthusiasm and technical advances in plastic reconstruction of the mitral valve were overshadowed by the development of prosthetic and bioprosthetic valves. With long-term follow-up studies came the realization that the complication rates of prosthetic mitral valves and the durability of bioprostheses were less than ideal. The use of annuloplasty rings and standardization of mitral repair techniques have made these procedures more universally reliable and the excellent results reproducible. Due to the pathological diversity of mitral regurgitation, many different techniques are used to correct the various lesions. Many centers are reporting hospital mortality, survival, freedom from thromboembolism, freedom from reoperation, freedom from infective endocarditis, and freedom from valve-related complications results that compare favorably with those following mitral valve replacement. The preservation of the papillary muscles and chordae tendinea during mitral reconstruction, as well as a lack of foreign materials, contribute to the enhanced systolic function with improved survival and lower complication rates following mitral repair compared with replacement. With improved results and technical advances, the indications for mitral repair have expanded to encompass a broader diversity of lesions and earlier operative intervention. [References: 263]





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