Acute effects of balloon valvuloplasty and pacing on left ventricular performance in children with moderate pulmonary valve stenosis, analysed by systolic and diastolic pressure-volume relationships

Right ventricular overload of volume and/or pressure type may affect left ventricular systolic and diastolic function. This has been shown in animal studies and has been suggested in non-invasive studies in man. Altered geometry of the left ventricle, myocardial hypertrophy and changes in contractile state may be responsible for the change in function. Balloon valvuloplasty is an effective treatment for isolated valvular pulmonary stenosis in children, and results in an immediate decrease of right ventricular systolic pressure. Whether this results in immediate changes in left ventricular performance is unknown. Eight children (age 5.2 to 13.9 years) with moderate pulmonary valve stenosis underwent pulmonary balloon valvuloplasty under general anaesthesia. Left ventricular function measurements before and after valvuloplasty were performed using a combined micromanometer-conductance catheter to obtain end-systolic (ESPVR) and end-diastolic (EDPVR) pressure-volume relationships employing inferior vena cava occlusion both at normal and pacing-induced increased heart rates. Pulmonary valvuloplasty resulted in a decrease in peak systolic right ventricular pressure from 62.8 ± 13.5 to 34.4 ± 7.3 mmHg (P<0.001), without significant changes in left ventricular systolic and end-diastolic pressure, or in cardiac index. The ESPVR was fitted to a linear function to obtain the slope (E(es)) and the volume intercept at 75 mmHg (V 75 ). The EDPVR was fitted to an exponential function. At baseline, E(es) was 1.68 ± 0.99 mmHg.ml -1 and V 75 was 33.6 ± 21.8 ml. Neither valvuloplasty nor pacing, which increased mean heart rate from 81 to 112 beats.min -1 (P<0.001), resulted in significant changes of the parameters E(es) or V 75 . The EDPVR was not affected by valvuloplasty either, but pacing resulted in a change of its stiffness constant from 0.042 ± 0.019 to 0.034 ± 0.018 mmHg.ml -1 (P<0.05) and pressure intercept from 0.97 ± 0.51 to 1.37 ± 0.86mmHg (P<0.05). The effect of pacing on left ventricular function before and after valvuloplasty was comparable. Neither balloon dilatation for moderate valvular pulmonary stenosis, nor pacing within the physiological range results in immediate changes in left ventricular contractile performance in children.