title: Instantaneous coronary collateral function during supine bicycle exercise.
abstract: OBJECTIVE
  The instantaneous response of the collateral circulation to isometric physical exercise in patients with non-occlusive coronary artery disease (CAD) is not known.
  
  
  RESULTS
  Thirty patients (age 59 +/- 9 years) undergoing percutaneous coronary intervention because of stable CAD were included in the study. Collateral function was determined before and during the last minute of a 6 min protocol of supine bicycle exercise during radial artery access coronary angiography. Collateral flow index (CFI, no unit) was determined as the ratio of mean distal coronary occlusive to mean aortic pressure both subtracted by central venous pressure. To avoid confounding due to recruitment of coronary collaterals by repetitive balloon occlusions, patients were randomly assigned to a group 'rest first' with CFI measurement during rest followed by CFI during exercise, and to a group 'exercise first' with antecedent CFI measurement during exercise before CFI at rest. Simultaneously, coronary collateral conductance (occlusive myocardial blood flow per aorto-coronary pressure drop) was determined by myocardial contrast echocardiography in the last 10 consecutive patients. Overall, CFI increased from 0.168 +/- 0.118 at rest to 0.262 +/- 0.166 during exercise (P = 0.0002). The exercise-induced change in CFI did not differ statistically in the two study groups. Exercise-induced CFI reserve (CFI during exercise divided by CFI at rest) was 2.2 +/- 1.8. Overall, rest to peak bicycle exercise change of coronary collateral conductance was from 0.010 +/- 0.010 to 1.109 +/- 0.139 mL/min/100 mmHg (P < 0.0001); the respective change was similar in both groups.
  
  
  CONCLUSIONS
  In patients with non-occlusive CAD, collateral flow instantaneously doubles during supine bicycle exercise as compared with the resting state. ClinicalTrials.gov Identifier: NCT00947050.
authors.affiliation: Department of Cardiology, University Hospital, CH-3010 Bern, Switzerland.
authors.forename: Mario
authors.initials: M
authors.lastname: Togni
authors.forename: Steffen
authors.initials: S
authors.lastname: Gloekler
authors.forename: Pascal
authors.initials: P
authors.lastname: Meier
authors.forename: Stefano F
authors.initials: SF
authors.lastname: de Marchi
authors.forename: Tobias
authors.initials: T
authors.lastname: Rutz
authors.forename: Hélène
authors.initials: H
authors.lastname: Steck
authors.forename: Tobias
authors.initials: T
authors.lastname: Traupe
authors.forename: Christian
authors.initials: C
authors.lastname: Seiler
mesh_terms: D000368:Aged; D000787:Angina Pectoris / Q000503:physiopathology; D021721:Balloon Occlusion; D006328:Cardiac Catheterization; D003097:Collateral Circulation / Q000502:physiology*; D017023:Coronary Angiography; D003324:Coronary Artery Disease / Q000503:physiopathology* / Q000628:therapy; D003326:Coronary Circulation / Q000502:physiology; D004562:Electrocardiography; D015444:Exercise / Q000502:physiology*; D005080:Exercise Test; D005260:Female; D006439:Hemodynamics / Q000502:physiology; D006801:Humans; D008297:Male; D008875:Middle Aged