title: Residual and recurrent gradients after septal myectomy for hypertrophic cardiomyopathy-mechanisms of obstruction and outcomes of reoperation.
abstract: OBJECTIVE
  The aims of the present study were to identify the mechanisms of residual or recurrent left ventricular outflow tract obstruction in patients undergoing repeat septal myectomy for hypertrophic cardiomyopathy and to assess the early and late results of reoperation.
  
  
  METHODS
  From January 1980 to June 2012, we performed 52 repeat myectomies in 51 patients. We reviewed the medical records and preoperative transthoracic echocardiograms to evaluate the adequacy of the previous resection and mechanism of left ventricular outflow tract obstruction. The complications of previous and repeat myectomy, New York Heart Association class, and survival were analyzed.
  
  
  RESULTS
  The mean interval from previous myectomy to reoperation was 43 ± 51 months. In 6 patients (12%) residual or recurrent gradients were caused by isolated midventricular obstruction. In the remaining 46 operations, the mechanism of residual or recurrent gradients was identified as systolic anterior motion of mitral valve-related subaortic obstruction caused by inadequate length of previous subaortic septal excision in 31 patients (59% of the total), both an inadequate length and an inadequate depth of septectomy in 13 patients (25%), and both residual subaortic obstruction due to systolic anterior motion of the mitral valve and midventricular obstruction in 2 patients (4%). Preoperatively, 96% of patients were in New York Heart Association class III or IV; postoperatively, 93.8% were in class I or II (P < .001). The 10-year survival after reoperation was 98% and similar to that of an age- and gender-matched Minnesota population (P = .46).
  
  
  CONCLUSIONS
  The most common cause of recurrent left ventricular outflow tract obstruction and symptoms in patients undergoing septal myectomy has been an inadequate length of septal excision. Reoperation is safe, with excellent long-term survival and functional improvement.
authors.affiliation: Division of Cardiovascular Surgery, Mayo Clinic, Rochester, Minn; Department of Thoracic and Cardiovascular Surgery, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea.
authors.forename: Yang Hyun
authors.initials: YH
authors.lastname: Cho
authors.affiliation: Division of Cardiovascular Surgery, Mayo Clinic, Rochester, Minn; University of Barcelona, Barcelona, Spain.
authors.forename: Eduard
authors.initials: E
authors.lastname: Quintana
authors.affiliation: Division of Cardiovascular Surgery, Mayo Clinic, Rochester, Minn. Electronic address: schaff@mayo.edu.
authors.forename: Hartzell V
authors.initials: HV
authors.lastname: Schaff
authors.affiliation: Division of Cardiovascular Disease, Mayo Clinic, Rochester, Minn.
authors.forename: Rick A
authors.initials: RA
authors.lastname: Nishimura
authors.affiliation: Division of Cardiovascular Surgery, Mayo Clinic, Rochester, Minn.
authors.forename: Joseph A
authors.initials: JA
authors.lastname: Dearani
authors.affiliation: Department of Anesthesiology, Mayo Clinic, Rochester, Minn.
authors.forename: Martin D
authors.initials: MD
authors.lastname: Abel
authors.affiliation: Division of Cardiovascular Disease, Mayo Clinic, Rochester, Minn.
authors.forename: Steve
authors.initials: S
authors.lastname: Ommen
mesh_terms: D000328:Adult; D006348:Cardiac Surgical Procedures / Q000009:adverse effects / Q000401:mortality; D002312:Cardiomyopathy, Hypertrophic / Q000150:complications / Q000175:diagnosis / Q000401:mortality / Q000503:physiopathology / Q000601:surgery*; D005260:Female; D006346:Heart Septum / Q000503:physiopathology / Q000601:surgery*; D006801:Humans; D053208:Kaplan-Meier Estimate; D008297:Male; D008875:Middle Aged; D011183:Postoperative Complications / Q000401:mortality / Q000503:physiopathology / Q000601:surgery*; D012008:Recurrence; D012086:Reoperation; D012307:Risk Factors; D013997:Time Factors; D016896:Treatment Outcome; D014694:Ventricular Outflow Obstruction / Q000175:diagnosis / Q000209:etiology / Q000401:mortality / Q000503:physiopathology / Q000601:surgery*; D055815:Young Adult