Related Experiment Videos
Effects of venous pressure on coronary circulation and intramyocardial fluid mechanics
I Izrailtyan1, H F Frasch, J Y Kresh
1Department of Cardiothoracic Surgery and Medicine, Likoff Cardiovascular Institute, Hahnemann University, Philadelphia, Pennsylvania 19102-1192.
Insights
Increased right heart pressure elevates intramyocardial tissue pressure and alters coronary flow dynamics in rabbit hearts. This suggests venous pressure significantly impacts coronary circulation by modifying the extravascular environment.
Area of Science:
- Cardiovascular Physiology
- Cardiac Mechanics
- Hemodynamics
Background:
- Coronary circulation is influenced by pressures within the heart and myocardium.
- Understanding intramyocardial tissue pressure (IMP) is crucial for comprehending coronary flow dynamics.
Purpose of the Study:
- To investigate the interplay between right heart pressure (RHP), coronary perfusion pressure (CPP), and IMP.
- To analyze coronary flow mechanics and effluent partitioning under varying RHP conditions.
Main Methods:
- Utilized an isolated Krebs-Henseleit perfused rabbit heart model.
- Measured IMP, CPP, and coronary flow at different RHP levels (0, 15, 25 mmHg).
- Assessed the partitioning of coronary outflow between left and right heart drainage.
Main Results:
- A parallel upward shift in the IMP-inflow relationship was observed with increasing RHP.
- IMP at zero coronary inflow significantly increased with rising RHP in both beating and arrested hearts.
- Coronary perfusion pressure-inflow relationship also shifted to higher pressures.
- The fraction of coronary outflow directed to the left heart increased substantially with elevated RHP.
Conclusions:
- Intramyocardial partitioning of coronary outflow plays a key role in mediating venous pressure effects on coronary circulation.
- Coronary venous pressure interacts with the extravascular environment to modulate effective back pressure influencing arterial inflow.
Abstract:
This investigation examined the interaction between right heart pressure (RHP), coronary perfusion pressure (CPP), intramyocardial tissue pressure (IMP), and coronary flow mechanics, including partitioning of coronary effluent in the isolated Krebs-Henseleit perfused rabbit heart. The major new finding was a parallel shift in the IMP-inflow relationship to a higher tissue pressure level in response to an increase in RHP. Accompanying the rise in RHP from 0 to 15 and 25 mmHg, IMP at zero coronary inflow in the beating (and arrested) heart increased from 5.8 +/- 1.0 (7.7 +/- 1.2) to 16.3 +/- 1.2 (17.9 +/- 1.3) and 28.6 +/- 1.7 (26.4 +/- 2.0) mmHg, respectively. A concomitant parallel shift in the CPP-inflow relation to higher pressures was consistently observed. The fraction of total coronary flow drained by the right heart was not constant. A higher partition of coronary outflow to the left heart (7.8 +/- 3.8, 34.3 +/- 3.0, and 47.9 +/- 4.3%, respectively) accompanied the increase in RHP. Intramyocardial partitioning of coronary outflow pathways mediates the effects of venous pressure modulation on coronary circulation. The interaction between coronary venous pressure and the extravascular environment modifies the effective back pressure to arterial inflow.