title: Coronary grafts flow and cardiac pacing modalities: how to improve perioperative myocardial perfusion.
abstract: OBJECTIVE
  Aim of this study was to investigate modifications of coronary grafts flow during different pacing modalities after CABG.
  
  
  METHODS
  Two separate prospective studies were conducted in patients undergoing CABG and requiring intraoperative epicardial pacing. In a first study (22 patients) coronary grafts flows were measured during dual chamber pacing (DDD) and during ventricular pacing (VVI). In a second study (10 patients) flows were measured during DDD pacing at different atrio-ventricular (A-V) delay periods. A-V delay was adjusted in 25 ms increments from 25 to 250 ms and flow measurements were performed for each A-V delay increment. A transit time flowmeter was used for the measurements.
  
  
  RESULTS
  An average of 3.4 grafts/patient were performed. In the first study, average coronary graft flow was 47.4+/-20.8 ml/min during DDD pacing and 41.8+/-18.2 ml/min during VVI pacing (P = 0.0004). Furthermore average systolic pressure was 94.3+/-10.1 mmHg during DDD pacing and 89.6+/-12.2 mmHg during VVV pacing (P = 0.0007). No significant differences in diastolic pressure were recorded during the two different pacing modalities. In the second study, maximal flows were achieved during DDD pacing with an A-V delay of 175 ms (54+/-9.6 ml/min) and minimal flows were detected at 25 ms A-V delay (38.1+/-4.7 ml/min) (P=ns). No significant differences in systolic or diastolic blood pressure were noticed during the different A-V delays.
  
  
  CONCLUSIONS
  Grafts flowmetry provides an extra tool to direct supportive measures such as cardiac pacing after CABG. DDD mode with A-V delay around 175 ms. should be preferred to allow for maximal myocardial perfusion via the grafts.
authors.affiliation: Department of Cardiac Surgery, Cork University Hospital, Cork, Ireland. rgea@hotmail.com
authors.forename: Giuseppe
authors.initials: G
authors.lastname: D'Ancona
authors.forename: Martin
authors.initials: M
authors.lastname: Hargrove
authors.forename: John
authors.initials: J
authors.lastname: Hinchion
authors.forename: B C
authors.initials: BC
authors.lastname: Ramesh
authors.forename: Jehan Zeb
authors.initials: JZ
authors.lastname: Chughtai
authors.forename: Muhammad Nadeem
authors.initials: MN
authors.lastname: Anjum
authors.forename: Aonghus
authors.initials: A
authors.lastname: O'Donnell
authors.forename: Tom
authors.initials: T
authors.lastname: Aherne
mesh_terms: D002304:Cardiac Pacing, Artificial / Q000379:methods*; D001026:Coronary Artery Bypass / Q000379:methods*; D003326:Coronary Circulation; D006439:Hemodynamics; D006801:Humans; D007430:Intraoperative Care / Q000379:methods*; D011446:Prospective Studies; D014654:Vascular Patency