Assessement of ventricular contractile state and function in patients with univentricular heart

Abstract

To elucidate the ventricular contractile state and function in patients with univentricular heart, the ventricular volume, mass, ejection phase index, and wall stress were evaluated with biplane ventriculography and pressure measurement in 41 patients: 18 with left ventricular (LV) type (age, 6.4 ± 6.1 years) and 23 with right ventricular (RV) type (age, 5.7 ± 4.1 years), and data from patients with univentricular heart were compared with data from 19 normal control subjects (age, 7.2 ± 4.3 years). Althought the end-diastolic and end-systolic volumes were significantly greater in both types of univentricular heart than in the normal control group, the volumes for the LV and RV type patients did not differ from each other. The ejection fraction (EF) was depressed in both patient types of univentricular heart and was significantly (p < 0.005) lower in the RV type than in the LV type patients (0.56 ± 0.05 for LV type, 0.50 ± 0.07 for RV type, and 0.64 ± 0.03 for the control group). The ventricular mass was larger in both patient types of univentricular heart than in that of the control group, whereas the ratio of ventricular mass to end-diastolic volume was significantly (p < 0.001) lower in the RV type patients than in the LV type patients and the control group (0.79 ± 0.18 g/ml for LV type, 0.51 ± 0.10 for RV type, and 0.82 ± 0.13 for control group). End-systolic stress was significantly elevated in both types of univentricular heart (241 ± 45 for LV type, 328 ± 52 for RV type, and 205 ± 26 kdynes/cm2 for the control group) and significantly (p < 0.001) greater in the RV type than in the LV type patients. There was a significant inverse correlation (p < 0.001) between end-systolic stress and the ratio of mass to end-diastolic volume in all the patients. In 27 patients (12 patients for LV type, 15 for RV type) the mean normalized systolic ejection rate corrected for heart rate (MNSERc) clearly fell below the 95% confidence limit of the normal end-sysolic stress-MNSERc relation. The end-systolic stress:end-systolic volume ratio was also significantly depressed in both patient types of univentricular heart volume ratio (3.49 ± 1.77 for LV type, 40.7 ± 2.13 for RV type, and 7.20 ± 1.32 for the control group). In these variables, however, there were no significant differences between LV and RV type patients of univentricular heart. Thus, despite the absence of significant difference either in preload or myocardial contractile function between LV and RV type patients, afterload was significantly increased in RV type patients compared with LV type patients. Therefore, impaired ejection performance in RV type compared with that in LV type patients may be responsible for afterload mismatch caused by inadequate ventricular hypertrophy rather than by myocardial contractile dysfunction.