Coronary hemodynamic data in ischemic heart disease according to ischemic behavior during pacing

In order to study the circulatory changes induced by maximal atrial pacing in coronary patients, coronary sinus blood flow (CBF) measured by continuous thermodilution, lactate extraction coefficient (K), arteriovenous difference in oxygen (AVO2 diff), and aortic blood pressure (BP) were measured at basal state and at maximal heart rate (HRmax) in 11 patients without coronary disease (group I) and in 28 patients with severe coronary lesions, divided into two groups according to the absence (group IIa) or the presence (group IIb) of chest pain and ST-segment depression at HRmax X K was inverted in group IIb (24 +/- 17% vs -23 +/- 39%, p less than 0.001), but remained unchanged in group I and group IIa. Despite similar HRmax, percent increase in CBF was significantly lower in group IIb (54 +/- 34%), than in group I (113 +/- 54%, p less than 0.01). This contrasts with the higher values of the product of heart rate times systolic blood pressure (HR X SBP) as well as of diastolic blood pressure (DBP) in group IIb. The decrease in coronary resistances was lower in group IIb than in group I (p less than 0.001), and also lower than in group IIa (p less than 0.05). The ratio MVO2 X CBF/systolic BP X HRmax was significantly lowered only in group IIb (p less than 0.001) confirming the imbalance between myocardial oxygen supply and oxygen demand. In coronary patients, myocardial ischemia induced by atrial pacing is related to an insufficient increase in CBF, well evidenced by continuous thermodilution.