Coronary hemodynamic data in ischemic heart disease according to ischemic behavior during pacing
Related Experiment Videos
Insights
Maximal atrial pacing reveals that coronary patients with chest pain experience insufficient coronary sinus blood flow (CBF) increase, indicating myocardial ischemia. This study highlights CBF
Area of Science:
- Cardiovascular Physiology
- Myocardial Ischemia Research
- Coronary Artery Disease
Background:
- Maximal atrial pacing is used to study circulatory changes in coronary patients.
- Assessing myocardial oxygen supply and demand balance is crucial in managing coronary artery disease.
Purpose of the Study:
- To investigate circulatory changes during maximal atrial pacing in coronary patients.
- To determine the relationship between atrial pacing, coronary blood flow, and myocardial ischemia.
Main Methods:
- Continuous thermodilution measured coronary sinus blood flow (CBF).
- Lactate extraction coefficient (K), arteriovenous oxygen difference (AVO2 diff), and blood pressure were recorded.
- Patients were categorized into non-coronary disease and coronary artery disease groups, with the latter further divided based on chest pain during pacing.
Main Results:
- Coronary patients experiencing chest pain (group IIb) showed an inverted lactate extraction coefficient (K) and a significantly lower increase in CBF compared to controls.
- Despite similar maximal heart rates, group IIb exhibited higher heart rate x systolic blood pressure (HR x SBP) and diastolic blood pressure (DBP).
- Reduced decrease in coronary resistances and a lowered ratio of myocardial oxygen consumption to supply were observed in group IIb, confirming oxygen supply-demand imbalance.
Conclusions:
- Myocardial ischemia in coronary patients induced by atrial pacing is linked to an inadequate increase in coronary sinus blood flow.
- Continuous thermodilution is an effective method for evidencing insufficient CBF during pacing-induced ischemia.
- The findings underscore the importance of assessing coronary blood flow dynamics in patients with severe coronary lesions.
Abstract:
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.