title: Mechanisms of Myocardial Ischemia in Hypertrophic Cardiomyopathy: Insights From Wave Intensity Analysis and Magnetic Resonance.
abstract: Angina is common in hypertrophic cardiomyopathy (HCM) and is associated with abnormal myocardial perfusion. Wave intensity analysis improves the understanding of the mechanics of myocardial ischemia.
  
  
  
  Wave intensity analysis was used to describe the mechanisms underlying perfusion abnormalities in patients with HCM.
  
  
  
  Simultaneous pressure and flow were measured in the proximal left anterior descending artery in 33 patients with HCM and 20 control patients at rest and during hyperemia, allowing calculation of wave intensity. Patients also underwent quantitative first-pass perfusion cardiac magnetic resonance to measure myocardial perfusion reserve.
  
  
  
  Patients with HCM had a lower coronary flow reserve than control subjects (1.9 ± 0.8 vs. 2.7 ± 0.9; p = 0.01). Coronary hemodynamics in HCM were characterized by a very large backward compression wave during systole (38 ± 11% vs. 21 ± 6%; p < 0.001) and a proportionately smaller backward expansion wave (27% ± 8% vs. 33 ± 6%; p = 0.006) compared with control subjects. Patients with severe left ventricular outflow tract obstruction had a bisferiens pressure waveform resulting in an additional proximally originating deceleration wave during systole. The proportion of waves acting to accelerate coronary flow increased with hyperemia, and the magnitude of change was proportional to the myocardial perfusion reserve (rho = 0.53; p < 0.01).
  
  
  
  Coronary flow in patients with HCM is deranged. Distally, compressive deformation of intramyocardial blood vessels during systole results in an abnormally large backward compression wave, whereas proximally, severe left ventricular outflow tract obstruction is associated with an additional deceleration wave. Perfusion abnormalities in HCM are not simply a consequence of supply/demand mismatch or remodeling of the intramyocardial blood vessels; they represent a dynamic interaction with the mechanics of myocardial ischemia that may be amenable to treatment.
authors.affiliation: NIHR Cardiovascular Biomedical Research Unit, Royal Brompton Hospital, London, United Kingdom. Electronic address: claire.raphael@gmail.com.
authors.forename: Claire E
authors.initials: CE
authors.lastname: Raphael
authors.affiliation: Institute of Cardiovascular Medicine and Science, Liverpool Heart and Chest Hospital, Liverpool, United Kingdom.
authors.forename: Robert
authors.initials: R
authors.lastname: Cooper
authors.affiliation: Department of Bioengineering, Imperial College, London, United Kingdom.
authors.forename: Kim H
authors.initials: KH
authors.lastname: Parker
authors.affiliation: NIHR Cardiovascular Biomedical Research Unit, Royal Brompton Hospital, London, United Kingdom.
authors.forename: Julian
authors.initials: J
authors.lastname: Collinson
authors.affiliation: NIHR Cardiovascular Biomedical Research Unit, Royal Brompton Hospital, London, United Kingdom.
authors.forename: Vassilis
authors.initials: V
authors.lastname: Vassiliou
authors.affiliation: NIHR Cardiovascular Biomedical Research Unit, Royal Brompton Hospital, London, United Kingdom.
authors.forename: Dudley J
authors.initials: DJ
authors.lastname: Pennell
authors.affiliation: NIHR Cardiovascular Biomedical Research Unit, Royal Brompton Hospital, London, United Kingdom.
authors.forename: Ranil
authors.initials: R
authors.lastname: de Silva
authors.affiliation: National Institutes of Health, Bethesda, Maryland.
authors.forename: Li Yueh
authors.initials: LY
authors.lastname: Hsu
authors.affiliation: National Institutes of Health, Bethesda, Maryland.
authors.forename: Anders M
authors.initials: AM
authors.lastname: Greve
authors.affiliation: International Centre for Circulatory Health, Imperial College, London, United Kingdom.
authors.forename: Sukh
authors.initials: S
authors.lastname: Nijjer
authors.affiliation: International Centre for Circulatory Health, Imperial College, London, United Kingdom.
authors.forename: Chris
authors.initials: C
authors.lastname: Broyd
authors.affiliation: NIHR Cardiovascular Biomedical Research Unit, Royal Brompton Hospital, London, United Kingdom.
authors.forename: Aamir
authors.initials: A
authors.lastname: Ali
authors.affiliation: NIHR Cardiovascular Biomedical Research Unit, Royal Brompton Hospital, London, United Kingdom.
authors.forename: Jennifer
authors.initials: J
authors.lastname: Keegan
authors.affiliation: International Centre for Circulatory Health, Imperial College, London, United Kingdom.
authors.forename: Darrel P
authors.initials: DP
authors.lastname: Francis
authors.affiliation: International Centre for Circulatory Health, Imperial College, London, United Kingdom.
authors.forename: Justin E
authors.initials: JE
authors.lastname: Davies
authors.affiliation: University College London, London, United Kingdom.
authors.forename: Alun D
authors.initials: AD
authors.lastname: Hughes
authors.affiliation: National Institutes of Health, Bethesda, Maryland.
authors.forename: Andrew
authors.initials: A
authors.lastname: Arai
authors.affiliation: Department of Cardiology, University of East Anglia, Norwich, United Kingdom.
authors.forename: Michael
authors.initials: M
authors.lastname: Frenneaux
authors.affiliation: Institute of Cardiovascular Medicine and Science, Liverpool Heart and Chest Hospital, Liverpool, United Kingdom.
authors.forename: Rod H
authors.initials: RH
authors.lastname: Stables
authors.affiliation: NIHR Cardiovascular Biomedical Research Unit, Royal Brompton Hospital, London, United Kingdom.
authors.forename: Carlo
authors.initials: C
authors.lastname: Di Mario
authors.affiliation: NIHR Cardiovascular Biomedical Research Unit, Royal Brompton Hospital, London, United Kingdom.
authors.forename: Sanjay K
authors.initials: SK
authors.lastname: Prasad
mesh_terms: D000328:Adult; D000368:Aged; D001783:Blood Flow Velocity; D001794:Blood Pressure; D057791:Cardiac Imaging Techniques; D002312:Cardiomyopathy, Hypertrophic / Q000150:complications / Q000000981:diagnostic imaging* / Q000503:physiopathology*; D003326:Coronary Circulation; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D017202:Myocardial Ischemia / Q000000981:diagnostic imaging* / Q000209:etiology / Q000503:physiopathology*; D055815:Young Adult
keywords: CMR; angina; cardiovascular magnetic resonance; left ventricular outflow tract obstruction; perfusion