title: Comparison of Left Ventricular Myocardial Structure and Function in Patients with Aortic Stenosis and Those with Pure Aortic Regurgitation.
abstract: OBJECTIVE
  We aimed to support the structural and functional distinction between aortic stenosis (AS) and aortic regurgitation (AR).
  
  
  METHODS
  Biopsy specimens taken from 70 selected patients (35 with AS and 35 with AR) undergoing aortic valve replacement (AVR) were analyzed for their cardiomyocyte dimensions and structure, interstitial fibrosis and contractile function. To determine normal values of contractile function, 10 donor hearts were analyzed.
  
  
  RESULTS
  Cardiomyocyte diameter was higher in AS than in AR (22.7 ± 2.2 vs. 13.2 ± 0.7 µm, p < 0.001). Length was higher in AR (121.2 ± 9.4 vs. 95.6 ± 3.7 µm, p < 0.001). Collagen volume fraction was increased in both AS and AR, but was lower in the AS specimens (7.7 ± 2.3 vs. 8.9 ± 2.3, p = 0.01). Myofibril density was reduced in AR (38 ± 4 vs. 48 ± 5%, p < 0.001). Cardiomyocyte diameter and length were closely linked to the relative left ventricular (LV) wall thickness (R2= 0.85, p < 0.001 and R2= 0.68, p = 0.003). The cardiomyocytes of AS patients had higher Fpassive(6.6 ± 0.3 vs. 4.6 ± 0.2 kN/m2, p < 0.001), but their total force was comparable. Fpassivewas also significantly higher in AS patients with restrictive rather than pseudo-normal LV filling (7.3 ± 0.5 vs. 6.7 ± 0.6, p = 0.004). In AS patients, but not in AR patients, Fpassiveshowed a significant association with the cardiomyocyte diameter (R2= 0.88, p < 0.001 vs. R2= 0.31, p = 0.6).
  
  
  CONCLUSIONS
  LV myocardial structure and function differ in AS and AR, allowing for compensative adjustment of the diastolic/systolic properties of the myocardium. © 2015 S. Karger AG, Basel.
authors.affiliation: Department of Cardiac Surgery, University Federico II School of Medicine, Naples, Italy.
authors.forename: Vito
authors.initials: V
authors.lastname: Mannacio
authors.forename: Elia
authors.initials: E
authors.lastname: Guadagno
authors.forename: Luigi
authors.initials: L
authors.lastname: Mannacio
authors.forename: Mariarosaria
authors.initials: M
authors.lastname: Cervasio
authors.forename: Anita
authors.initials: A
authors.lastname: Antignano
authors.forename: Michele
authors.initials: M
authors.lastname: Mottola
authors.forename: Cesare
authors.initials: C
authors.lastname: Gagliardi
authors.forename: Carlo
authors.initials: C
authors.lastname: Vosa