title: Coronary perfusion: impact of flow dynamics and geometric design of 2 different aortic prostheses of similar size.
abstract: BACKGROUND
  Aortic valve replacement leads to improvement of coronary flow but not to complete normalization. Coronary hypoperfusion contributes to higher left ventricular mass persistence, arrhythmias, congestive heart failure and sudden death. This prospective study compares 2 similarly sized aortic prostheses (mechanical and porcine) regarding coronary flow and hemodynamic performances in patients who underwent surgery for pure aortic stenosis.
  
  
  METHODS
  Sixty patients having undergone aortic valve replacement for pure aortic stenosis with Medtronic Mosaic Ultra bioprosthesis 21 mm (n = 30) or St Jude Regent mechanical valve 19 mm (n = 30) were evaluated preoperatively and 12 months postoperatively comparing the coronary flow and the hemodynamic behavior. Echocardiography and cardiac positron emission tomography were performed at rest and during exercise or adenosine maximal stimulation, respectively.
  
  
  RESULTS
  The St Jude Regent mechanical valve, compared with the Medtronic Mosaic Ultra bioprosthesis, had reduced coronary flow reserve (2.1 ± 0.3 vs 2.3 ± 0.2; P = .003), less favorable systolic/diastolic time ratio (0.87 ± 0.02 vs 0.78 ± 0.03; P < .001), and higher mean transprosthetic gradient (46 ± 11 vs 38 ± 9; P = .003) during exercise. Multivariate analysis of impaired coronary reserve related indexed effective orifice area less than 0.65 cm/m(2) (risk ratio [RR], 1.9; 95% confidence intervals [CI], 1.5-2.8; P < .001), mechanical valve (RR, 2.5; 95% CI, 1.7-3.3; P < .001), and systolic/diastolic time ratio greater than 0.75 (RR, 2.6; 95% CI, 1.8-3.8; P < .001), as well as high transprosthetic gradient (RR, 1.7; 95% CI, 1.3-2.4; P < .001) ) during exercise with coronary reserve less than 2.2.
  
  
  CONCLUSIONS
  Improvement of coronary flow and reserve was more evident for bioprostheses than for mechanical valves. The bioprostheses demonstrated superior hemodynamics during exercise, which may have some impact on exercise capability during normal daily life.
authors.affiliation: Department of Cardiac Surgery, University of Naples Federico II, Naples, Italy. vitomannacio2@libero.it
authors.forename: Vito
authors.initials: V
authors.lastname: Mannacio
authors.forename: Luigi
authors.initials: L
authors.lastname: Di Tommaso
authors.forename: Vincenzo
authors.initials: V
authors.lastname: De Amicis
authors.forename: Paolo
authors.initials: P
authors.lastname: Stassano
authors.forename: Carlo
authors.initials: C
authors.lastname: Vosa
mesh_terms: D000241:Adenosine; D000368:Aged; D001021:Aortic Valve / Q000503:physiopathology / Q000601:surgery*; D001024:Aortic Valve Stenosis / Q000175:diagnosis / Q000503:physiopathology / Q000601:surgery*; D001705:Bioprosthesis; D016009:Chi-Square Distribution; D003326:Coronary Circulation; D015150:Echocardiography, Doppler; D025401:Echocardiography, Stress; D005080:Exercise Test; D005260:Female; D006350:Heart Valve Prosthesis; D019918:Heart Valve Prosthesis Implantation / Q000009:adverse effects / Q000295:instrumentation*; D006439:Hemodynamics; D006801:Humans; D007558:Italy; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D049268:Positron-Emission Tomography; D011237:Predictive Value of Tests; D011446:Prospective Studies; D011474:Prosthesis Design; D020127:Recovery of Function; D018570:Risk Assessment; D012307:Risk Factors; D016896:Treatment Outcome; D014665:Vasodilator Agents
chemical_list: D014665:Vasodilator Agents; D000241:Adenosine