title: Improved myocardial ischemic response and enhanced collateral circulation with long repetitive coronary occlusion during angioplasty: a prospective study.
abstract: OBJECTIVE
  The goal of the study was to evaluate the progressive increase in ischemic threshold with multiple sequential transient coronary occlusions and to assess the role of the collateral circulation in adaptation to ischemia.
  
  
  BACKGROUND
  It has been observed that the duration of balloon inflations during coronary angioplasty can be gradually prolonged during subsequent dilations with a reduction in patient symptoms and diminished ischemic electrocardiographic (ECG) changes. Although the mechanism has not been fully explained, recruitment of coronary collateral circulation induced by repeated coronary occlusion has been reported. The stimuli for recruitment and the natural history of coronary collateral circulation are not understood.
  
  
  METHODS
  Seventeen patients with isolated stenosis of the left anterior descending coronary artery and a normal left ventricle were enrolled. Angioplasty consisted of five successive prolonged inflations. Sequential changes in clinical, intracoronary ECG and left ventricular indexes of myocardial ischemia were examined. Coronary collateral channels were evaluated during balloon inflations by ipsilateral and contralateral injections of contrast medium and hemodynamically by occlusion pressure.
  
  
  RESULTS
  An improved tolerance to myocardial ischemia with repetitive coronary occlusions was demonstrated by a significant reduction of angina, ST segment deviation, left ventricular filling pressure and less impairment of ejection fraction. Left ventricular wall motion abnormalities remained unchanged. Collateral angiographic grade did not change in 7 patients and increased in 10.
  
  
  CONCLUSIONS
  This study confirms a progressive adaptation of myocardial ischemia to repetitive coronary occlusions and supports the concept that sequential episodes of myocardial ischemia are a stimulating factor for the recruitment of collateral channels in humans. These results also suggest that enhancement of recruitable collateral circulation might be an underlying mechanism of myocardial ischemic preconditioning.
authors.affiliation: Service de Cardiologie, Hôpital Charles Nicolle, Universitaire de Rouen, France.
authors.forename: A
authors.initials: A
authors.lastname: Cribier
authors.forename: L
authors.initials: L
authors.lastname: Korsatz
authors.forename: R
authors.initials: R
authors.lastname: Koning
authors.forename: P
authors.initials: P
authors.lastname: Rath
authors.forename: H
authors.initials: H
authors.lastname: Gamra
authors.forename: G
authors.initials: G
authors.lastname: Stix
authors.forename: S
authors.initials: S
authors.lastname: Merchant
authors.forename: C
authors.initials: C
authors.lastname: Chan
authors.forename: B
authors.initials: B
authors.lastname: Letac
mesh_terms: D000328:Adult; D000368:Aged; D000787:Angina Pectoris / Q000209:etiology / Q000503:physiopathology*; D015906:Angioplasty, Balloon, Coronary / Q000009:adverse effects; D002985:Clinical Protocols; D003097:Collateral Circulation / Q000502:physiology*; D003327:Coronary Disease / Q000503:physiopathology* / Q000628:therapy; D004562:Electrocardiography; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies