RT Book, Section
A1 Karamlou, Tara
A1 Permut, Lester C.
A1 Ricci, Marco
A1 Cohen, Gordon A.
A2 Yuh, David D.
A2 Vricella, Luca A.
A2 Yang, Stephen C.
A2 Doty, John R.
SR Print(0)
ID 1104597708
T1 Surgery for Left Ventricular Outflow Tract Obstruction in Children
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=1104597708
RD 2024/04/17
AB EpidemiologyLeft  ventricular  outflow  tract  obstruction  (LVOTO)  occurs  in  2.8  of  10,000  live  births,  accounting  for  3  to  6  percent  of  congenital  heart  defects.MorphologyLVOTO  is  valvar  in  50  percent,  subvalvar  in  25  percent,  and  supravalvar  in  10  percent  of  cases.  Multilevel  obstruction  is  present  in  15  percent  of  cases.PathophysiologyObstruction  at  any  level  causes  increased  left  ventricular  systolic  pressure  and  wall  stress  and  consequent  left  ventricular  hypertrophy.  Left  ventricular  hypertrophy  produces  subendocardial  ischemia  and  diastolic  dysfunction.  Eventually,  myocardial  fibrosis  occurs  with  associated  left  ventricular  systolic  dysfunction.  Low  cardiac  output,  pulmonary  edema,  and  ventricular  arrhythmias  may  occur  late  and  are  associated  with  increased  mortality.Clinical  features:Neonates  with  critical  valvar  aortic  stenosis  (AS)  present  with  low  cardiac  output  and  shock,  requiring  emergency  treatment.  Other  forms  of  LVOTO  are  often  asymptomatic  and  may  be  detected  by  the  presence  of  a  heart  murmur  or  abnormalities  on  ECG.  Chest  pain,  dyspnea,  and  palpitations  occur  with  increased  activity  as  the  degree  of  obstruction  worsens.  Symptoms  at  rest  occur  with  long-standing  LVOTO.DiagnosisDiagnostic  evaluation  is  performed  in  children  with  a  characteristic  systolic  ejection  murmur.  Echocardiography  allows  diagnosis  and  determines  the  level(s)  of  obstruction.  The  left  ventricular  outflow  tract  gradient  can  be  estimated  with  the  use  of  Doppler  flow  velocity,  and  ventricular  systolic  and  diastolic  function  can  be  assessed.  Diagnostic  cardiac  catheterization  is  rarely  necessary.TreatmentNeonates  with  critical  valvar  AS  and  morphology  amenable  to  biventricular  repair  respond  well  to  percutaneous  transcatheter  balloon  valvotomy.  Aortic  valve  replacement  is  required  in  older  children.  Enlargement  of  a  small  annulus  may  be  achieved  with  the  use  of  Konno  aortoventriculoplasty.  Options  for  valve  replacement  include  a  bioprosthetic  or  mechanical  prosthesis,  or  an  autograft  (Ross  procedure),  but  all  have  significant  disadvantages  in  the  pediatric  population.  Discrete  subaortic  membrane  is  resected  via  aortotomy,  but  diffuse  tunnel-like  narrowing  requires  a  modified  Konno  procedure.  A  variety  of  aortoplasty  techniques  are  available  for  patients  with  supravalvar  AS.OutcomesExcellent  outcomes,  with  operative  mortality  of  less  than  5  percent,  are  achieved  in  most  patients.  Reoperation  to  upsize  valves  is  expected  in  pediatric  patients  with  somatic  growth  after  aortic  valve  replacement  or  for  structural  valve  deterioration.  Discrete  subaortic  membrane  recurs  in  approximately  15  to  20  percent  of  patients  despite  successful  initial  repair,  and  is  dependent  on  the  preoperative  gradient.