Effects of elevated coronary sinus pressure on coronary blood flow and left ventricular function: Implications after the Fontan operation

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, ≃15 mm Hg) and severe (phase II, ≃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 inn 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.