title: Effects of dual-chamber pacing on regional myocardial deformation in patients with hypertrophic obstructive cardiomyopathy.
abstract: BACKGROUND
  This study examined the effects of dual-chamber pacing (DDD) on regional myocardial deformation, as determined by echocardiographic strain and strain rate (SR) imaging, in patients with hypertrophic obstructive cardiomyopathy (HOCM).
  
  
  RESULTS
  Fourteen patients (11 men, 3 women; mean age 55 +/-16 years) who had been on long-term DDD (mean period 7.4 +/- 2.1 years) underwent strain and SR imaging. Before and after DDD, the peak strain (%) and SR (s(-1)) during systole were assessed in 8 segments in 4 left ventricular (LV) walls. With DDD turned on, peak strain and SR were significantly increased in the basal anteroseptal (strain -10.2 +/- 6.8 to -1.0 +/- 6.4, p<0.005; SR -0.76 +/- 0.46 to 0.05 +/- 0.58, p<0.001) and septal segments (strain -11.2 +/- 8.9 to -2.2 +/- 7.7, p<0.005; SR -0.85 +/- 0.54 to -0.19 +/- 0.75, p<0.05), but not in the basal posterior (strain -15.0 +/- 13.0 to -13.4 +/- 9.2, p=NS; SR -1.37 +/- 0.57 to -1.93 +/- 0.65, p=NS) and lateral segments (strain -18.1 +/- 10.2 to -15.7 +/- 5.6, p=NS; SR -1.33 +/- 0.68 to -0.84 +/- 0.88, p=NS). These findings were associated with a modest, but significant, change in the LV pressure gradient (24 +/- 12 mmHg to 14 +/- 7 mmHg, p<0.001).
  
  
  CONCLUSIONS
  In patients with HOCM, DDD appeared to produce myocardial lengthening in the basal septum during systole, which may have implications for the mechanism of reducing LV outflow obstruction during DDD.
authors.affiliation: Third Division, Department of Internal Medicine, Osaka Medical College, Takatsuki, Japan.
authors.forename: Tomomi
authors.initials: T
authors.lastname: Hozumi
authors.forename: Takahide
authors.initials: T
authors.lastname: Ito
authors.forename: Michihiro
authors.initials: M
authors.lastname: Suwa
authors.forename: Yasuhiko
authors.initials: Y
authors.lastname: Sakai
authors.forename: Yasushi
authors.initials: Y
authors.lastname: Kitaura
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D002312:Cardiomyopathy, Hypertrophic / Q000000981:diagnostic imaging / Q000503:physiopathology* / Q000628:therapy*; D015150:Echocardiography, Doppler; D005260:Female; D006321:Heart / Q000503:physiopathology*; D006339:Heart Rate; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008297:Male; D008875:Middle Aged; D010138:Pacemaker, Artificial; D012189:Retrospective Studies; D016277:Ventricular Function, Left