Related Experiment Video
Updated: Aug 14, 2026
Biventricular Assessment of Cardiac Function and Pressure-Volume Loops by Closed-Chest Catheterization in Mice
Published on: June 15, 2020
Quantitative assessment of independent contributions of pericardium and septum to direct ventricular interaction
1Department of Medicine, The University of Calgary, Calgary, Alberta, Canada T2N 2T9.
Insights
Direct ventricular interaction significantly impacts left ventricular filling, especially at higher right ventricular pressures. The pericardium and septum play key roles in this interaction, influencing cardiac function.
Area of Science:
- Cardiovascular Physiology
- Cardiac Mechanics
- Ventricular Interaction
Background:
- Disentangling direct ventricular interaction (DI) from other factors like the pericardium and septum is challenging in intact animals.
- Understanding DI is crucial for comprehending how ventricular pressures and volumes influence each other.
Purpose of the Study:
- To independently assess the effects of left ventricular venous return and right ventricular end-diastolic pressure on ventricular interaction.
- To quantify the contributions of the pericardium and septum to direct ventricular interaction.
Main Methods:
- Utilized a right-heart bypass model to independently manipulate left ventricular venous return and right ventricular end-diastolic pressure.
- Measured left ventricular minor-axis diameters to estimate left ventricular volume index (LVVI).
- Calculated right ventricular-to-left ventricular pressure gain (DeltaLVEDP/DeltaRVEDP) to quantify ventricular coupling.
Main Results:
- Increased left ventricular venous return consistently increased left ventricular volume index at all tested right ventricular end-diastolic pressures.
- Right ventricular-to-left ventricular pressure gain increased with rising right ventricular end-diastolic pressure when the pericardium was closed, indicating dynamic ventricular coupling.
- Opening the pericardium reduced ventricular interaction, and accounting for the septum's contribution eliminated remaining interaction.
Conclusions:
- Direct ventricular interaction significantly influences left ventricular pressure-volume relationships and can necessitate substantial increases in right ventricular output to maintain left ventricular filling.
- Ventricular coupling is minimal at low right ventricular end-diastolic pressures and approaches 1:1 at high pressures with an intact pericardium.
- The septum is a significant mediator of direct ventricular interaction, even after the pericardium's influence is considered.
Abstract:
In the intact animal, it is difficult to discriminate between the independent effects of series and direct ventricular interaction (DI) or the individual contributions of the pericardium and septum to DI. Left ventricular (LV) venous return (LVVR) and right ventricular (RV) end-diastolic pressure (RVEDP) were varied independently in a right-heart bypass model. LV minor-axis diameters were measured, and the product of the two diameters was used as an index of LV volume (LVVI). At each RVEDP (0, 5, 10, and 15 mmHg), increased LVVR caused an increased LVVI. When RVEDP was increased, increased pump output was required to maintain a given LVVI. RV-to-LV pressure gain (DeltaLVEDP/DeltaRVEDP) reflects coupling and DI. With the pericardium closed, the gain was dependent on RVEDP; when RVEDP was increased from 0 to 5 mmHg, the gain was not statistically different from zero, indicating little or no DI. When RVEDP was increased from 10 to 15 mmHg, the gain was not statistically different from 1.0, indicating approximately 1:1 coupling of the ventricles. Opening the pericardium reduced the gain, but significant interaction remained. When the septal contribution was accounted for, the remaining interaction was eliminated. In conclusion, DI substantially affects LVEDP-volume relations. Considerable increases in RV output may be required to counterbalance increased constraint to LV filling. With the pericardium closed, RV-to-LV coupling is minimal when RVEDP is low and increases to 1:1 coupling when RVEDP is high. Opening the pericardium reduces DI, but significant septum-mediated interaction remains.
