RT Book, Section
A1 Yarbrough, William M.
A1 Ikonomidis, John S.
A2 Yuh, David D.
A2 Vricella, Luca A.
A2 Yang, Stephen C.
A2 Doty, John R.
SR Print(0)
ID 1104589963
T1 Aortic Valve Replacement
T2 Johns Hopkins Textbook of Cardiothoracic Surgery
YR 2014
FD 2014
PB McGraw-Hill Education
PP New York, NY
SN 978-0-07-166350-2
LK accesssurgery.mhmedical.com/content.aspx?aid=1104589963
RD 2024/04/18
AB EpidemiologyApproximately  100,000  aortic  valve  replacement  procedures  have  been  performed  in  the  United  States  in  the  last  10  years.  Most  patients  present  with  aortic  valve  pathology  that  requires  replacement  between  ages  60  and  80.  Replacement  for  aortic  stenosis  is  performed  much  more  commonly  (85  percent)  than  is  replacement  for  aortic  insufficiency.PathophysiologyWith  aortic  stenosis,  there  is  a  decrease  in  the  effective  valve  orifice  area,  resulting  in  progressive  obstruction  of  the  left  ventricle.  The  ventricle  adapts  through  concentric  hypertrophy,  which  increases  diastolic  stiffness  and  impairs  the  efficacy  of  diastolic  coronary  blood  flow.  Diastolic  dysfunction  precedes  systolic  dysfunction.  With  aortic  insufficiency,  gradual  ventricular  dilatation  occurs,  causing  an  increase  in  wall  stress.  This,  in  conjunction  with  the  decrease  in  diastolic  pressure,  reduces  diastolic  coronary  blood  flow.  With  continued  dilatation,  fibrosis  occurs,  increasing  ventricular  stiffness  and  impairing  diastolic  relaxation.  Eventually,  the  preload  reserve  of  the  ventricle  is  reached  and  further  dilatation  and  fibrosis  result  in  a  decline  in  systolic  function  that  may  not  be  recoverable  after  aortic  valve  replacement.Clinical  featuresAortic  stenosis  patients  complain  of  combinations  of  symptoms  of  chest  pain,  syncope,  and  congestive  heart  failure.  The  life  expectancy  of  patients  with  untreated  aortic  stenosis  who  present  with  angina  is  50  percent  at  5  years,  50  percent  at  3  years  with  syncope,  and  50  percent  at  2  years  with  congestive  heart  failure  symptoms.  A  small  proportion  of  patients  with  aortic  stenosis  present  with  sudden  death.  Aortic  insufficiency  has  a  more  insidious  onset  and  usually  is  characterized  by  the  development  of  slow  congestive  heart  failure  and  fatigue  symptoms.  Angina  pectoris  and  syncope  are  rare  in  these  patients.  These  patients  may  be  managed  on  medical  therapy  for  protracted  periods  with  an  acceptable  quality  of  life.DiagnosticsThe  work-up  for  candidates  for  aortic  valve  replacement  includes  echocardiography  to  estimate  ventricular  function  and  the  degree  of  stenosis  or  insufficiency  and  cardiac  catheterization  to  measure  cardiac  output,  calculate  aortic  valve  area,  and  image  the  coronary  arteries  for  significant  lesions.  A  careful  oral  examination  or  dental  consultation  is  very  important  to  prevent  postoperative  prosthetic  valve  infection.TreatmentAortic  valve  replacement  options  include  homograft,  stented  and  stentless  xenograft  tissue,  and  mechanical  valves.  The  decision  to  use  each  of  these  is  dependent  on  patient  age  and  valve  preference,  comorbid  conditions,  and  contraindications  to  the  use  of  anticoagulants.  A  variety  of  options  are  available  to  manage  potential  patient–prosthesis  mismatch  at  the  time  of  surgery.OutcomesThe  outcomes  of  tissue  valve  replacement  show  80  to  93  percent  freedom  from  structural  valve  failure  at  10  to  14  years.  Bleeding  and  thromboembolic  events  complicate  mechanical  valve  replacement  at  a  rate  of  approximately  4  percent  per  patient-year.  Homograft  valve  replacements  have  the  highest  freedom  from  structural  valve  deterioration,  with  rates  of  81  to  93  percent  at  15  years.  Survival  after  aortic  valve  replacement  is  dependent  more  on  patient  comorbidities  than  on  the  requirement  for  valve  replacement.  Postoperative  complications  specific  for  aortic  valve  replacement  include  complete  heart  block  (1  percent)  and  perivalvular  leaks  (1–2  percent).