title: Abnormal myocardial capillary density in apical hypertrophic cardiomyopathy can be assessed by myocardial contrast echocardiography.
abstract: BACKGROUND
  Myocardial ischemia and dysfunction can occur in hypertrophic cardiomyopathy (HCM) because of the high muscle-to-blood ratio, even without significant coronary artery disease. Microbubbles reside only in the intravascular space and myocardial video-intensity during systole results mostly from microbubbles within capillaries. The hypothesis explored in the present study was that an abnormal capillary density in apical HCM (ApHCM) can be demonstrated using myocardial contrast echocardiography (MCE).
  
  
  RESULTS
  The 56 patients were investigated (31 males, age 58 ± 9 years; 33 ApHCM, 9 hypertensive left ventricular hypertrophy [LVH], 14 controls). MCE was performed with low-mechanical-index power modulation imaging. Tissue Doppler imaging to assess myocardial contractile function was obtained at the mitral annulus (S'), and (99 m)Tc-MIBI SPECT was also performed. All ApHCM patients exhibited perfusion defects at the hypertrophied segments in the systolic phase during MCE, whereas SPECT showed normal or rather increased perfusion at those sites. The cyclic variation of video-intensity was exaggerated in ApHCM when compared with the LVH or control group (% of [systolic video-intensity]/[diastolic video-intensity]: 33.0 ± 12.3%, 88.3 ± 19.2% and 79.4 ± 13.9%, respectively [P<0.05]). Concurrently, MCE cyclic variation and perfusion defect size were related to decreased S' (P<0.05 for all).
  
  
  CONCLUSIONS
  A perfusion defect at the hypertrophied segment, representing abnormal myocardial capillary density, was observed in ApHCM patients during MCE. The extent of MCE cyclic variation and the perfusion defect size both correlate with decreased myocardial contractile property in ApHCM.
authors.affiliation: Cardiology Division, Yonsei Cardiovascular Center, Yonsei University College of Medicine, Seoul, Republic of Korea.
authors.forename: Jeonggeun
authors.initials: J
authors.lastname: Moon
authors.forename: In Jeong
authors.initials: IJ
authors.lastname: Cho
authors.forename: Chi Young
authors.initials: CY
authors.lastname: Shim
authors.forename: Jong-Won
authors.initials: JW
authors.lastname: Ha
authors.forename: Yangsoo
authors.initials: Y
authors.lastname: Jang
authors.forename: Namsik
authors.initials: N
authors.lastname: Chung
authors.forename: Se-Joong
authors.initials: SJ
authors.lastname: Rim
mesh_terms: D000368:Aged; D002196:Capillaries / Q000473:pathology*; D002312:Cardiomyopathy, Hypertrophic / Q000175:diagnosis / Q000000981:diagnostic imaging*; D016022:Case-Control Studies; D003324:Coronary Artery Disease / Q000175:diagnosis; D003326:Coronary Circulation; D004452:Echocardiography / Q000379:methods*; D005260:Female; D006801:Humans; D017379:Hypertrophy, Left Ventricular / Q000000981:diagnostic imaging; D008297:Male; D008875:Middle Aged; D009200:Myocardial Contraction; D017256:Technetium Tc 99m Sestamibi; D015899:Tomography, Emission-Computed, Single-Photon
chemical_list: D017256:Technetium Tc 99m Sestamibi