title: Deviation from Murray's law is associated with a higher degree of calcification in coronary bifurcations.
abstract: OBJECTIVE
  Murray's law describes the optimal branching anatomy of vascular bifurcations. If Murray's law is obeyed, shear stress is constant over the bifurcation. Associations between Murray's law and intravascular ultrasound (IVUS) assessed plaque composition near coronary bifurcations have not been investigated previously.
  
  
  METHODS
  In 253 patients plaque components (fibrous, fibro-fatty, necrotic core, and dense calcium) were identified by IVUS in segments proximal and distal to the bifurcation of a coronary side branch. The ratio of mother to daughter vessels was calculated according to Murray's law (Murray ratio) with a high Murray ratio indicating low shear stress. Analysis of variance was used to detect independent associations of Murray ratio and plaque composition.
  
  
  RESULTS
  Patients with a high Murray ratio exhibited a higher relative amount of dense calcium and a lower amount of fibrous and fibro-fatty tissue than those with a low Murray ratio. After adjustment for age, sex, cardiovascular risk factors or concomitant medications, the Murray ratio remained significantly associated with fibrous volume distal (F-ratio 4.90, P=0.028) to the bifurcation, fibro-fatty volume distal (F-ratio 4.76, P=0.030) to the bifurcation, and dense calcium volume proximal (F-ratio 5.93, P=0.016) and distal (F-ratio 5.16, P=0.024) to the bifurcation.
  
  
  CONCLUSIONS
  This study shows that deviation from Murray's law is associated with a high degree of calcification near coronary bifurcations. Individual deviations from Murray's law may explain why some patients are prone to plaque formation near vessel bifurcations.
authors.affiliation: Division of Geriatrics, Department of General Internal Medicine, Inselspital, Bern University Hospital, Switzerland.
authors.forename: Andreas W
authors.initials: AW
authors.lastname: Schoenenberger
authors.forename: Nadja
authors.initials: N
authors.lastname: Urbanek
authors.forename: Stefan
authors.initials: S
authors.lastname: Toggweiler
authors.forename: Robert
authors.initials: R
authors.lastname: Seelos
authors.forename: Peiman
authors.initials: P
authors.lastname: Jamshidi
authors.forename: Thérèse J
authors.initials: TJ
authors.lastname: Resink
authors.forename: Paul
authors.initials: P
authors.lastname: Erne
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000704:Analysis of Variance; D001696:Biomechanical Phenomena; D016009:Chi-Square Distribution; D017023:Coronary Angiography; D003324:Coronary Artery Disease / Q000000981:diagnostic imaging* / Q000503:physiopathology; D003326:Coronary Circulation; D003331:Coronary Vessels / Q000000981:diagnostic imaging* / Q000503:physiopathology; D005260:Female; D005355:Fibrosis; D006801:Humans; D008297:Male; D008875:Middle Aged; D008955:Models, Cardiovascular; D015999:Multivariate Analysis; D009336:Necrosis; D011237:Predictive Value of Tests; D011446:Prospective Studies; D012720:Severity of Illness Index; D013314:Stress, Mechanical; D013557:Switzerland; D018084:Ultrasonography, Interventional; D061205:Vascular Calcification / Q000000981:diagnostic imaging* / Q000503:physiopathology; D055815:Young Adult