title: Do changes in blood flow in the subclavian artery affect flow volume in IMA grafts after complete arterial revascularization with the T-graft technique?
abstract: BACKGROUND
  The T-graft procedure achieves complete arterial coronary revascularization with only two conduits. In this technique, all the bypass anastomoses are supplied by the left internal mammary artery (IMA). Changes in flow conditions or flow redistribution in the subclavian artery may thus sigificantly influence coronary perfusion. The objective of this study was to determine whether changes in blood flow in the subclavian artery affect the flow in IMA grafts in patients who have undergone complete arterial revascularization with T-grafts.
  
  
  METHODS
  Quantitative flow volume and flow profiles in the IMA graft and the proximal subclavian artery were measured with a flow-wire in 20 patients one week postoperatively. Following baseline measurements, brachial artery constriction was achieved by applying a blood pressure measurement cuff to the patient's left upper arm. After 5 minutes, quantitative flow in the IMA and in the proximal subclavian artery was assessed. The cuff was then released and the measurements repeated.
  
  
  RESULTS
  Flow in the subclavian artery changed significantly (p < 0.01) from baseline (355.4 +/- 95.2 ml/ min) to constriction (171.2 +/- 61.3 ml/min) and hyperemia (679.3 +/- 195.1 ml/min). Flow in the IMA graft remained constant irrespective of subclavian artery flow (75.4 +/- 26.2 ml/min vs. 78.0 +/- 28.9 ml/min vs. 75.5 +/- 29.3 ml/min, respectively). The flow profile in the IMA was similarily unchanged.
  
  
  CONCLUSIONS
  In patients in whom the coronary bypass blood flow is dependent on the left IMA, neither the quantitative flow volume nor the flow profile are altered by changes in blood flow of the subclavian artery.
authors.affiliation: Medizinische Klinik III (Kardiologie/Angiologie), Universitätskliniken des Saarlandes, Homburg/Saar, Germany. hennen@med-in.uni-sb.de
authors.forename: B
authors.initials: B
authors.lastname: Hennen
authors.forename: T
authors.initials: T
authors.lastname: Markwirth
authors.forename: B
authors.initials: B
authors.lastname: Scheller
authors.forename: H J
authors.initials: HJ
authors.lastname: Schäfers
authors.forename: O
authors.initials: O
authors.lastname: Wendler
mesh_terms: D000368:Aged; D001783:Blood Flow Velocity; D006328:Cardiac Catheterization; D017023:Coronary Angiography; D001026:Coronary Artery Bypass / Q000009:adverse effects / Q000379:methods*; D003327:Coronary Disease / Q000175:diagnosis / Q000503:physiopathology / Q000601:surgery*; D005260:Female; D005500:Follow-Up Studies; D006085:Graft Survival; D006801:Humans; D017078:Laser-Doppler Flowmetry; D008297:Male; D008323:Mammary Arteries / Q000637:transplantation*; D008875:Middle Aged; D011184:Postoperative Period; D011336:Probability; D011446:Prospective Studies; D013348:Subclavian Artery / Q000000981:diagnostic imaging* / Q000503:physiopathology*; D016896:Treatment Outcome; D014463:Ultrasonography