title: Non-invasive evaluation of mammary artery flow reserve and adequacy to increased myocardial oxygen demand.
abstract: OBJECTIVE
  To evaluate the flow reserve and adequacy to meet myocardial requests in stress conditions of mammary artery-left anterior descending (IMA-LAD) grafts using a non-invasive method.
  
  
  METHODS
  Patients (20) with angiographic evidence of normofunctioning left IMA-LAD grafts were submitted to dypiridamole Tl201 myocardial scintigraphy and concomitant transthoracic echo-doppler evaluation of the IMA flow at a mean interval of 32.5 months after surgery.
  
  
  RESULTS
  Under basal conditions, the mean peak and end flow velocities in systole were 0.39 and 0.06 m/s, respectively. In diastole, the mean peak and end flow velocities were 0.27 and 0.02 m/s and mean tele-diastolic flow velocity was 0.14 m/s, with a mean systolic/diastolic ratio of 1.51. After dypiridamole infusion, mean systolic velocities were 0.47 (peak) and 0.23 (end) m/s, respectively + 20 and + 283%, whereas mean diastolic velocities were 0.56 (peak) and 0.06 (end) m/s, +107 and +200%, respectively. Mean tele-diastolic flow velocity increased to 0.32 m/s (+128%) and the systolic-diastolic index changed to 0.85. In all cases no significant scintigraphic evidence of induced ischemia was demonstrated in the LAD region.
  
  
  CONCLUSIONS
  Transthoracic echo-doppler evaluation combined with Tl201 myocardial scintigraphy is a useful tool for the assessment of IMA flow reserve and adequacy to stress conditions. In the late postoperative period, the IMA shows the possibility of increasing the flow velocity, almost 2-fold; the increase in flow is prevalently diastolic and leads to a complete reversal of the physiological systolic/diastolic flow ratio. The flow reserve of IMA is always able to meet the augmented myocardial oxygen demand after dypiridamole infusion.
authors.affiliation: Department of Cardiac Surgery, Catholic University, Rome, Italy.
authors.forename: M
authors.initials: M
authors.lastname: Gaudino
authors.forename: M
authors.initials: M
authors.lastname: Serricchio
authors.forename: P
authors.initials: P
authors.lastname: Tondi
authors.forename: F
authors.initials: F
authors.lastname: Glieca
authors.forename: A
authors.initials: A
authors.lastname: Giordano
authors.forename: C
authors.initials: C
authors.lastname: Trani
authors.forename: P
authors.initials: P
authors.lastname: Pola
authors.forename: G
authors.initials: G
authors.lastname: Possati
mesh_terms: D000368:Aged; D003327:Coronary Disease / Q000503:physiopathology / Q000601:surgery*; D015150:Echocardiography, Doppler; D005260:Female; D006801:Humans; D007387:Internal Mammary-Coronary Artery Anastomosis; D008297:Male; D008323:Mammary Arteries / Q000000981:diagnostic imaging / Q000502:physiology*; D008875:Middle Aged; D009206:Myocardium / Q000378:metabolism; D010100:Oxygen / Q000378:metabolism; D011184:Postoperative Period; D011877:Radionuclide Imaging; D012039:Regional Blood Flow; D013794:Thallium Radioisotopes
chemical_list: D013794:Thallium Radioisotopes; D010100:Oxygen