title: Edge-to-edge mitral repair: gradients and three-dimensional annular dynamics in vivo during inotropic stimulation.
abstract: OBJECTIVE
  The edge-to-edge (Alfieri) mitral repair technique appears to be clinically promising, but the potential for functional mitral stenosis, especially with exercise, remains a concern. We used the myocardial marker method combined with Doppler echocardiography to evaluate mitral annular (MA) three-dimensional (3-D) dynamics and transvalvular gradients after leaflet approximation before and during dobutamine infusion.
  
  
  METHODS
  Eight adult sheep underwent implantation of eight myocardial markers around the MA and nine in the left ventricle. Mitral leaflet edges were approximated at the valve center and micromanometers were placed in the left ventricle and atrium. The animals were studied with biplane videofluoroscopy to determine 3-D marker coordinates for computation of precise 3-D MA area and left ventricular (LV) volume. Epicardial Doppler echocardiography measured peak and mean diastolic mitral valve gradients at baseline and during dobutamine infusion (10 microg/kg per min).
  
  
  RESULTS
  During dobutamine stimulation, left ventricular dP/dt increased from 1776+/-712 to 3390+/-618 mmHg/s (P=0.002), and cardiac output (CO) increased from 2.7+/-1.1 to 5.1+/-1.2 l/min (P=0.009). Mitral annular area (MAA) at end-diastole (ED) fell from 8.6+/-1.4 to 7.0+/-1.8 cm(2) (P=0.001) with inotropic stimulation, but only a modest increase was observed in mean (1.4+/-0.4 vs. 2.4+/-1.0 mmHg, P=0.046) and peak (2.7+/-0.8 vs. 4.9+/-2.5 mmHg, P=0.03) diastolic mitral valve gradients. MAA changed dynamically throughout the cardiac cycle, reflecting normal physiology, but the magnitude of MAA change was augmented during inotropic stimulation (18+/-5% and 27+/-4% for control and dobutamine, respectively; P=0.004).
  
  
  CONCLUSIONS
  Dobutamine increased CO by 89% and decreased ED annular area by 19% after edge-to-edge repair, yet only a small increase in valve gradient occurred. Marker analysis showed enhanced dynamic motion of the mitral annulus. Thus, the edge-to-edge mitral valve repair was not associated with substantial transvalvular obstruction during high flow conditions and did not perturb normal MA 3-D dynamics in normal ovine hearts.
authors: Department of Cardiovascular and Thoracic Surgery, Stanford University School of Medicine, Stanford, CA, USA.
authors: T A
authors: TA
authors: Timek
authors: S L
authors: SL
authors: Nielsen
authors: D
authors: D
authors: Liang
authors: D T
authors: DT
authors: Lai
authors: P
authors: P
authors: Dagum
authors: G T
authors: GT
authors: Daughters
authors: N B
authors: NB
authors: Ingels
authors: D C
authors: DC
authors: Miller
mesh_terms: D000818:Animals; D001696:Biomechanical Phenomena; D002302:Cardiac Output; D006348:Cardiac Surgical Procedures; D002316:Cardiotonic Agents / Q000494:pharmacology; D004280:Dobutamine / Q000494:pharmacology; D006439:Hemodynamics; D007091:Image Processing, Computer-Assisted; D008297:Male; D008943:Mitral Valve / Q000187:drug effects / Q000502:physiology* / Q000601:surgery*; D023421:Models, Animal; D012756:Sheep
chemical_list: D002316:Cardiotonic Agents; D004280:Dobutamine