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Effects of elevated coronary sinus pressure on coronary blood flow and left ventricular function. Implications after
T Miura1, T Hiramatsu, J M Forbess
1Department of Cardiovascular Surgery, Children's Hospital, Boston, Mass 02115, USA.
Insights
Elevated coronary sinus pressure (CSP) after Fontan surgery can decrease coronary blood flow (CBF) and impair left ventricular (LV) relaxation over time, potentially affecting heart function post-surgery.
Area of Science:
- Cardiovascular Physiology
- Pediatric Cardiology
- Surgical Outcomes
Background:
- Post-Fontan operation, elevated systemic venous pressure is common.
- Coronary sinus pressure (CSP) elevation may occur, potentially impacting coronary perfusion and left ventricular (LV) function.
- Understanding the effects of elevated CSP is crucial for managing postoperative outcomes.
Purpose of the Study:
- To investigate the short-term effects of elevated coronary sinus pressure (CSP) on coronary blood flow (CBF) and left ventricular (LV) function.
- To assess the potential for CSP elevation to cause postoperative LV dysfunction after the Fontan procedure.
Main Methods:
- Isolated blood-perfused juvenile lamb hearts (n=14) were used.
- Coronary sinus pressure (CSP) was acutely elevated in 7 hearts (CSHT group) to moderate (15 mm Hg) and severe (30 mm Hg) levels.
- Coronary blood flow (CBF) and LV function parameters were measured and compared to a control group (C group).
Main Results:
- Coronary blood flow (CBF) significantly decreased in the CSHT group during both moderate and severe CSP elevations.
- LV systolic function (max developed pressure, max+dP/dt, max-dP/dt) and LV end-diastolic pressure (LVEDP) showed no significant changes.
- The time constant of LV isovolumic relaxation (tau) significantly worsened during severe CSP elevation.
Conclusions:
- Short-term elevation of CSP did not impair LV systolic function or LVEDP.
- Reduced CBF and impaired LV relaxation (increased tau) were observed with elevated CSP.
- These findings suggest potential deleterious effects on LV function with sustained CSP elevation post-Fontan.
Background:
After the Fontan operation there is elevated systemic venous pressure, and the coronary sinus pressure (CSP) may also be elevated depending on the operative technique. Elevated CSP can potentially alter coronary perfusion and thereby be a cause for postoperative left ventricular (LV) dysfunction.
Methods And Results:
The effects of elevated CSP on coronary blood flow (CBF) and LV function were evaluated in 14 isolated blood-perfused juvenile lamb hearts. After baseline measurements were made, CSP was elevated by a 10-minute inflation of a balloon catheter inserted into the coronary sinus via the hemiazygos vein in 7 hearts (CSHT group) to cause moderate (phase I, approximately 15 mm Hg) and severe (phase II, approximately 30 mm Hg) elevations of mean CSP at a constant coronary perfusion pressure (80 mm Hg). The results were compared with results from 7 hearts continuously perfused without elevation of CSP (C group). Mean CSP in the CSHT group was elevated from 0.4 +/- 1.9 to 16.4 +/- 2.4 mm Hg during phase I and to 32.6 +/- 3.6 mm Hg during phase II. CBF in the CSHT group decreased to 89.7 +/- 5.2% in phase I and to 79.0 +/- 13.2% in phase II, and these values were significantly lower than those in the C group (98.5 +/- 6.7% in phase I and 106.8 +/- 16.0% in phase II; P < .05 each). There were no significant differences in maximum developed pressure (DP), max+dP/dt, max-dP/dt, or LV end-diastolic pressure (LVEDP) at a fixed volume between the CSHT group and the C group either in phase I or phase II. The time constant of pressure decline during LV isovolumic relaxation (tau) showed no significant difference in phase I, but in phase II tau was significantly higher in the CSHT group (116.2 +/- 7.8%) than that in the C group (106.3 +/- 8.5%; P < .05).
Conclusions:
Elevated CSP on a short-term basis did not affect the LV systolic function indexes (max DP, max+dP/dt), max-dP/dt, or LVEDP at a fixed volume, but tau did appear to worsen and CBF decreased during CSP elevation. These actions might have deleterious effects on the LV over a longer time period.