Determination of volume-time curves for the right ventricle and its outflow tract for functional analyses.

PURPOSE: The determination of right ventricular volumes and function is of increasing interest for the postoperative care of patients with congenital heart defects. The presentation of volumetry data in terms of volume-time curves allows a comprehensive functional assessment. By using manual contour tracing, the generation of volume-time curves is exceedingly time-consuming. METHODS: This study describes a fast and precise method for determining volume-time curves for the right ventricle and for the right ventricular outflow tract. The method applies contour detection and includes a feature for identifying the right ventricular outflow tract volume. The segregation of the outflow tract is performed by four-dimensional curved smooth boundary surfaces defined by prespecified anatomical landmarks. RESULTS: The comparison with manual contour tracing demonstrates that the method is accurate and improves the precision of the measurement. Compared to manual contour tracing the bias is <0.1% ± 4.1% (right ventricle) and -2.6% ± 20.0% (right ventricular outflow tract). The standard deviations of inter- and intraobserver variabilities for determining the volume of the right ventricular outflow tract are reduced to less than half the values of manual contour tracing. The time consumption per patient is reduced from 341 ± 80 min (right ventricle) and 56 ± 11 min (right ventricular outflow tract) using manual contour tracing to 46 ± 9 min for a combined analysis of right ventricle and right ventricular outflow tract. CONCLUSION: The analysis of volume-time curves for the right ventricle and its outflow tract discloses new evaluation methods in clinical routine and science.

Interventional creation of an atrial septal defect and its impact on right ventricular function: an animal study with the pressure-volume conductance system.

BACKGROUND: The aim of our study was to assess the suitability of different interventional techniques to create an atrial septal defect (ASD) and to evaluate the short-term effects of right ventricular (RV) volume overload on RV contractility in the growing swine. METHODS: Thirteen ASD and six control animals were studied. An ASD was created by balloon dilatation (BD) of the fossa ovalis (n = 4) or by implantation of a multi-perforated Amplatzer Septal Occluder (n = 4) or a patch-less nitinol device (n = 5). After 4.8 (3.9-6.0) weeks, the amounts of left-to-right shunting (Qp/Qs) and RV contractility (end systolic elastance - Ees) were assessed. RESULTS: In the ASD group, a significant left-to-right shunt could be documented (Qp/Qs 1.5 ± ± 0.4). However, a shunt was absent in the BD subgroup (Qp/Qs 1.1 ± 0.1). In animals with devices implanted, a significant relationship between the post-mortem ASD area and Qp/Qs was found (r = 0.68, p < 0.05). Compared to controls, RV contractility was not significantly impaired at rest and during dobutamine in ASD animals (Ees: 0.40 ± 0.20 vs 0.54 ± 0.12 and 0.75 ± 0.29 vs 1.04 ± 0.24 mm Hg/mL, p = NS for both). CONCLUSIONS: Device implantation is necessary to create a patent ASD resulting in significant left-to-right shunting. In an experimental ASD model, a five week period of chronic RV volume overload does not alter RV contractility significantly.