Left ventricular pressure-volume characteristics in congenital heart disease.

SUMMARY The continuous pressure-volume relationships throughout the cardiac cycle were evaluated in children with tetralogy of Fallot, isolated ventricular septal defect, and patent ductus arteriosus. Biplane cineangiocardiography and simultaneous left ventricu-lar pressures were utilized for data acquisition. Normal pressure-volume loops demonstrated only small changes in left ventricular volume during the isovolumic periods. In tetralogy of Fallot, there was a decrease in left ventricular volume during the interval of the "isovolumic" contraction with 12 to 43% of the total stroke volume being ejected during this phase. A decrease in left ventricular volume during this time was also found in large ventricular septal defects; however, volume changes during this interval were minimal in those patients judged to have small defects. With large left-to-right shunts of comparable magnitude, the relative area of the pressure-volume loop was greater in patent ductus arteriosus as compared with ven-tricular defects. Both conditions demonstrated marked increase in stroke volume, with peak systolic pressures rising higher in those patients with patent ducus arteriosus as compared to those with ventricular septal defect. Additional Indexing Words: Tetralogy of Fallot Isolated ventricular septal defect Patent ductus arteriosus Biplane cineangiocardiography T HE NEED for quantitative description use of digital computers to perform complex of the functional status of the left ven-and time-consuming calculations has become tricle in a variety of congenital cardiac an important adjunct in humans for the de-defects is well appreciated by cardiologists. tailed study of ventricular muscle mechanics, The ability to determine the changing volume which previously could be evaluated only in characteristics of the left ventricle by means laboratory animals. of biplane cineangiocardiography while mea-The left ventricular pressure-volume rela-suring the ventricular pressure provides a tionships should vary throughout the cardiac method for detailed study of changing events cycle in a variety of congenital cardiac throughout the cardiac cycle. Additionally, the anomalies, depending upon the integrity of the ventricular septum and the competence of the mitral and aortic valves. Because of the From the Departments of Pediatrics and Radiology, marked variation in left ventricular dynamics roduced by different congenital cardiac de-Durham, North Carolina. fects,1'2 a logical initial step in the study of Supported in part by U. S. Public Health Service quantitative left ventricular function in cardi-relationship throughout the cardiac cycle. This Carolina 27706.