Diastolic ventricular septal motion in atrial septal defect: Analysis of M-mode echocardiograms in 31 patients

Previous echocardiographic studies suggest that diastolic motion of the ventricular septum reflects relative filling of the right and left ventricles. We studied 31 patients with atrial septal defect by M-mode echocardiography. Early diastolic posterior ventricular septal motion (DPSM) occurred in all patients. Measurement of DPSM correlated with pulmonary to systemic flow ratios (Qp:Qs) (r = 0.64, p < 0.001). All 15 patients with DPSM > 5 mm had a Qp:Qs > 2.5:1, whereas only 8 of 16 patients with DPSM < 5 mm had a shunt this large (p < 0.003). DPSM > 5 mm in patients with atrial septal defect is a specific but not sensitive echocardiographic sign of a large left-to-right shunt. Our findings substantiate the hypothesis that diastolic motion of the ventricular septum reflects relative filling of the ventricles.     

Quantification of left to right atrial shunts with velocity-encoded cine nuclear magnetic resonance imaging.

OBJECTIVES. The purpose of this study was to evaluate the ability of velocity-encoded nuclear magnetic resonance (NMR) imaging to quantify left to right intracardiac shunts in patients with an atrial septal defect. BACKGROUND. Quantification of intracardiac shunts is clinically important in planning therapy. METHODS. Velocity-encoded NMR imaging was used to quantify stroke flow in the aorta and in the main pulmonary artery in a group of patients who were known to have an increased pulmonary to systemic flow ratio (Qp/Qs). The velocity-encoded NMR flow data were used to calculate Qp/Qs, and these values were compared with measurements of Qp/Qs obtained with oximetric data derived from cardiac catheterization and from stroke volume measurements of the two ventricles by using volumetric data from biphasic spin echo and cine NMR images obtained at end-diastole and end-systole. RESULTS. Two independent observers measured Qp/Qs by using velocity-encoded NMR imaging in 11 patients and found Qp/Qs ranging from 1.4:1 to 3.9:1. These measurements correlated well with both oximetric data (r = 0.91, SEE = 0.35) and ventricular volumetric data (r = 0.94, SEE = 0.30). Interobserver reproducibility for Qp/Qs by velocity-encoded NMR imaging was good (r = 0.97, SEE = 0.20). CONCLUSIONS. Velocity-encoded NMR imaging is an accurate and reproducible method for measuring Qp/Qs in left to right shunts. Because it is completely noninvasive, it can be used to monitor shunt volume over time.     

Quantification of pulmonary and systemic blood flow by magnetic resonance velocity mapping in the assessment of atrial-level shunts

The objective of this study was to assess the feasibility and accuracy of magnetic resonance (MR) velocity mapping to calculate pulmonary-to-systemic flow ratio (Qp : Qs) in patients with a suspected or diagnosed atrial-level shunt. During a one-year period, all patients referred to our department for further evaluation of an atrial-level shunt underwent the same imaging protocol. Multiphase-multisection gradient-echo MR image sets of the heart were acquired to measure left and right ventricular stroke volumes for validation. Ascending aorta and main pulmonary artery volume flow were measured with MR velocity mapping. Qp : Qs ratios were calculated from both stroke volume data and flow data. Twelve patients, including 6 children, were studied. Six patients had an established diagnosis of atrial septal defect, and the other 6 patients were suspected to have an atrial-level shunt. Measurements of left and right ventricular stroke corresponded closely with those of aortic (r=0.98) and pulmonary flow (r=0.99) respectively, and Qp : Qs flow ratios agreed with stroke volume ratios (r=0.92). In 5 patients with a suspected shunt, the diagnosis could be rejected. Shunts were demonstrated in the other 7 patients. MR velocity mapping offers an accurate method to measure aortic and pulmonary artery volume flow that can be useful in the evaluation of atrial-level shunts, in order to establish a definite diagnosis and/or to quantify the Qp : Qs ratio.     

Transatrial septal velocity measurement by Doppler echocardiography in atrial septal defect: correlation with Qp:Qs ratio

Right atrial velocities measured perpendicular to the atrial septum by Doppler echocardiography in patients with atrial septal defects (ASD) have a discernible morphology that may bear a relation to shunt magnitude. The integral of the right atrial Doppler waveform was compared with shunt magnitude measured at cardiac catheterization or nuclear shunt scan in 17 ASD patients. For control subjects, the mean right atrial velocity was 15 +/- 4 cm/s (+/- standard deviation) and that for ASD patients was 41 +/- 11 cm/s (p less than 0.001). Doppler pulmonary-to-systemic flow ratio (Qp:Qs) correlated with catheterization Qp:Qs ratio (n = 9, r = 0.85, SEE = 0.27) and with nuclear Qp:Qs ratios (n = 8, r = 0.60, SEE = 0.51). Mean transatrial septal velocity in ASD patients correlated with catheterization Qp:Qs ratio (n = 9, r = 0.8, SEE = 6.0) and with simultaneous Doppler Qp:Qs ratio (n = 16, r = 0.89, SEE = 4.9, y = 16.2 +/- 8.3). Although Qp:Qs ratio can be approximated by measuring pulmonary and systemic flow by Doppler echocardiography in many ASD patients, this newly described method allows estimation of Qp:Qs ratio. It is useful when these more conventional measurements cannot be performed because of turbulence or when inadequate imaging prevents Doppler pulmonary to systemic flow measurement.     

Quantification of left to right shunt in atrial septal defect using systolic time intervals derived from pulsed Doppler velocimetry.

Systolic time intervals derived from Doppler velocimetry measurements were used instead of direct pulmonary to systemic flow ratio measurements in adults with atrial septal defect to quantify left to right atrial shunts. Thirteen normal subjects and 25 patients with uncomplicated atrial septal defect confirmed by cardiac catheterisation were studied. The pulmonary to systemic flow ratio (Qp:Qs) expressing the shunt size was determined by the Fick method; in normal subjects the Qp:Qs ratio was assumed to be equal to 1.0. The pulsed Doppler analogue velocity recording of flow in the pulmonary artery and the ascending aorta was taken as indicating the ejection time of each ventricle and the Q wave of the electrocardiogram as indicating the onset of systole. From these measurements the ratios of the pre-ejection periods to the ejection times (haemodynamic ratio) were calculated for each ventricle and the ratios of each variable (pre-ejection period, ejection time, and haemodynamic ratio) were calculated for both ventricles. Significant differences were found between the normal subjects and the patients with atrial septal defect for all these ratios. When the Doppler findings and the Fick measurements of Qp:Qs were compared the best linear correlation coefficient was for the left to right haemodynamic ratio. It is concluded that the use of a ratio involving several variables, such as the pre-ejection period and the ejection time for both ventricles, improves the reliability of this method, which appears to be applicable in adults.     

Clinical value of Doppler echocardiography in the determination of shunt size in atrial septal defect of adult patients

The purpose of this study was to assess the clinical utility of pulsed Doppler echocardiography in the determination of shunt flow magnitude in adults with an atrial septal defect. Therefore, in 24 unselected, consecutive adult patients with an ostium-secundum type atrial septal defect, and in 16 patients without heart disease, Doppler echocardiography was performed to measure blood flow in the right and left ventricular outflow tract. In eight patients with an atrial septal defect, pulmonary flow measurement was impossible because of pulmonary insufficiency or poor visualization of the pulmonary annulus. The ratio between the pulmonary (Qp) and systemic blood flow (Qs) was between 0.83 and 1.13 in the control group and between 1.31 and 4.46 in patients with an atrial septal defect. In the control group the correlation between Qs and Qp was r = 0.96 (SEE = 0.417 l/min, y = 1.05x - 0.21). The correlation between Qp/Qs, determined by oximetry and pulsed Doppler echocardiography in patients with an atrial septal defect, was significant (r = 0.82, SEE = 0.54). Systematic differences between invasive and non-invasive shunt calculations did not occur. Thus, pulsed Doppler echocardiography is clinically useful in the determination of shunt flow magnitude in about two thirds of adult patients with an atrial septal defect and provides precise information for the decision for conservative or operative treatment.     

Accuracy of Doppler echocardiography in quantification of left to right shunts in adult patients with atrial septal defect

In previous experimental and pediatric studies, the ratio of pulmonary to systemic flow (Qp/Qs) was accurately estimated by Doppler echocardiography in various cardiac shunt lesions. The purpose of this study was to assess the accuracy of pulsed Doppler echocardiography in determining the magnitude of shunt flow in adult patients with an ostium secundum type atrial septal defect. In 32 patients with high quality echocardiograms and excellent Doppler signals, blood flow was measured in the right and left ventricular outflow tract by Doppler echocardiography. In 16 patients without heart disease, the correlation (r) between systemic (Qs) and pulmonary (Qp) blood flow was 0.96 (SEE = 0.417 liter/min, y = 1.05x - 0.21) and the mean Qp/Qs ratio was 1.01 +/- 0.09. In 16 patients with an atrial septal defect, the Qp/Qs ration measured by oximetry ranged from 1.34 to 4.61 and by pulsed Doppler echocardiography from 1.31 to 4.46 (p = NS). In these 16 patients, the correlation between the Qp/Qs ratio determined by oximetry and pulsed Doppler echocardiography was significant (r = 0.82, SEE = 0.54). In the total group of 32 patients, the correlation was stronger (r = 0.93, SEE = 0.37). Systematic differences between the invasive and noninvasive shunt calculations did not occur. Thus, in adult patients with an atrial septal defect of the secundum type and high quality echocardiograms, the magnitude of left to right shunt can be accurately assessed by pulsed Doppler echocardiography. In the absence of pulmonary hypertension, pulsed Doppler echocardiography provides precise information for the decision to undertake conservative or operative treatment.     

Quantification of left to right shunt in atrial septal defect using systolic time intervals derived from pulsed Doppler velocimetry

Systolic time intervals derived from Doppler velocimetry measurements were used instead of direct pulmonary to systemic flow ratio measurements in adults with atrial septal defect to quantify left to right atrial shunts. Thirteen normal subjects and 25 patients with uncomplicated atrial septal defect confirmed by cardiac catheterisation were studied. The pulmonary to systemic flow ratio (Qp:Qs) expressing the shunt size was determined by the Fick method; in normal subjects the Qp:Qs ratio was assumed to be equal to 1.0. The pulsed Doppler analogue velocity recording of flow in the pulmonary artery and the ascending aorta was taken as indicating the ejection time of each ventricle and the Q wave of the electrocardiogram as indicating the onset of systole. From these measurements the ratios of the pre-ejection periods to the ejection times (haemodynamic ratio) were calculated for each ventricle and the ratios of each variable (pre-ejection period, ejection time, and haemodynamic ratio) were calculated for both ventricles. Significant differences were found between the normal subjects and the patients with atrial septal defect for all these ratios. When the Doppler findings and the Fick measurements of Qp:Qs were compared the best linear correlation coefficient was for the left to right haemodynamic ratio. It is concluded that the use of a ratio involving several variables, such as the pre-ejection period and the ejection time for both ventricles, improves the reliability of this method, which appears to be applicable in adults.     

Usefulness of echocardiographic assessment of right ventricular and pulmonary trunk size for estimating magnitude of left-to-right shunt in children with atrial septal defect

M-mode and 2-dimensional echocardiographic studies were performed in 42 patients, aged 1 to 16 years (mean 6), with a secundum or sinus venosus type atrial septal defect (ASD) and normal pulmonary artery pressure. Twenty normal children served as a control group. In patients with ASD the echocardiographic variables were correlated with the magnitude of the left-to-right shunt (Qp/Qs) calculated by the Fick principle. Although M-mode echocardiograms showed increased right ventricular (RV) dimension in 69% of the patients, the correlation between RV dimension index (RV dimension/body surface area) and Qp/Qs was weak (r = 0.49). When RV dimension was related to left ventricular (LV) dimension and expressed by the RV/LV ratio, 90% of the patients were found to have an abnormally large right ventricle. The correlation between the RV/LV ratio and Qp/Qs was fairly good (r = 0.64). In 33 patients (78%), the pulmonary trunk (PT) was adequately visualized and measured on 2-dimensional echocardiograms. The dimension of the PT was related to the aortic root dimension and expressed by the PT dimension/aortic dimension ratio. This ratio was 0.99 ± 0.06 in normal children and 1.35 ± 0.23 in patients with ASD (p <0.001). The PT/aortic ratio exceeded the upper limit of normal (the normal mean value + 2 standard deviations) in each of the 27 patients with a Qp/Qs of 1.5 or greater. In 5 of the 6 patients with a Qp/Qs of less than 1.5 the PT/aortic ratio was close to 1 and within the normal range. An excellent correlation (r = 0.89) was found between the PT/aortic ratio and Qp/Qs. The echocardlographic determination of the RV/LV ratio and particularly the PT/aortic ratio is therefore useful in the noninvasive estimation of the left-to-right shunt in ASD.     

Bidirectional shunt in uncomplicated atrial septal defect.

The presence of right to left shunts at atrial level in 40 patients with an uncomplicated atrial septal defect was determined by measuring the pulmonary vein to systemic artery oxygen stepdown . In six patients (group 1) a sizeable right to left shunt was found: left atrial oxygen stepdown was greater than or equal to 0.7 vol%, mean right to left shunt 0.67 1/min/m2 (range 0.36-1.0), and arterial oxygen saturation between 84% and 90.5%. The patients in group 1 did not show any differences from those with left to right shunts alone (group 2) as regards sex, cardiac rhythm, heart rate, "a" wave and mean right atrial pressure, end diastolic right ventricular pressure, morphology of diastolic right ventricular pressure curves, pulmonary to systemic vascular resistance ratio, size of the defect, and coexistence of anomalous pulmonary venous drainage. Patients with coexisting right to left shunts were, however, significantly older and had smaller left to right shunts. Thus an appreciable number of patients with uncomplicated atrial septal defects have major right to left shunts which are unrelated to pulmonary hypertension or right heart failure. These shunts may be detected by the usual oximetric techniques and apparently develop with age, which suggests that they result from changes associated with chronic right volume overload.     

Left to right atrial shunts in infants

At cardiac catheterization, 24 infants less than 1 year old had a left to right atrial shunt without other major cardiac lesions. Only 6 infants had cardiac symptoms, and there was no relation between symptoms and the size of the shunt. Six infants (including 2 who were less than 1 week old and were asymptomatic) had a pulmonary to systemic flow ratio (Qp:Qs) greater than 3. Clinical features were often atypical. Fifteen had harsh grade 3–4/6 systolic murmurs; only 10 had wide fixed splitting of the second heart sound. Splitting of the second heart sound was unrelated to the Qp:Qs. Two infants with a large shunt had no cardiomegaly. Electrocardiograms were not typical of atrial septal defect.

The shunt disappeared in 9 of 12 infants who underwent recatheterization and was not clinically detectable in 3 others whose shunt was large when under 2 weeks of age. Many shunts probably occurred through an incompetent foramen ovale, sometimes secondary to left-sided lesions. However, some children had a classic atrial septal defect that closed spontaneously. Since spontaneous closure of atrial septal defects occurs and there are many atypical features of these lesions in infants and younger children, it is possible that the incidence of this lesion is underestimated in infancy and early childhood.     

Afterload reduction treatment for large ventricular septal defects. Dependence of haemodynamic effects of hydralazine on pretreatment systemic blood flow.

The haemodynamic effects of hydralazine were studied in seven infants and a child, each with a large ventricular septal defect. Hydralazine, 0.3 mg/kg, was administered intravenously. This caused a lowering of pulmonary arterial pressure from 57 +/- 4 mmHg to 49 +/- 4 mmHg, and a lowering of left atrial pressure from 12 +/- 1 mmHg to 10 +/- 1 mmHg. Systemic vascular resistance was reduced from 19.0 +/- 2.4 units/m2 to 15.1 +/- 0.9 units/m2. Pulmonary vascular resistance was reduced in six cases and increased in two. Systemic blood flow (Qs) increased in six cases and was unchanged in one. It decreased in one case where the pretreatment Qs was high, that is 6.4 l/min per m2. Pulmonary blood flow (Qp) increased in six cases while it decreased in two. These two cases had a pretreatment Qs less than 3.0 l/min per m2. The pulmonary to systemic blood flow ratio (Qp/Qs ratio) decreased only in three patients who had Qs less than 3.0 l/min per m2 before hydralazine. In contrast, the Qp/Qs ratio increased in the five cases with higher pretreatment Qs. Thus, this study has found that the pretreatment Qs alters the effect of hydralazine on the Qp/Qs ratio in large ventricular septal defects, thus indicating that afterload reduction treatment with hydralazine may be effective in the management of large ventricular septal defects by reducing the Qp/Qs ratio in the cases that are associated with a low systemic blood flow.     

Right ventricular dilatation and intraventricular septal motion after surgical closure of atrial septal defect

The persistence of right ventricular dilatation and paradoxical interventricular septal motion are two echocardiographic abnormalities rarely reported after surgical closure of atrial septal defects. The aim of this study was to identify the predictive factors of these abnormalities in the long-term and to study their functional consequences. One hundred and two patients aged 18 +/- 14 years (range 1-62 years) underwent closure of atrial septal defects. Thirty-five patients were under 10 years of age, 33 were 10 to 20 years of age and 34 were over 20. Fifty-six patients were female. The rhythm was sinus in the great majority of cases (97%). Three patients, all over 40 years of age, were in atrial fibrillation. Before surgery, right ventricular dilatation was observed in 95 patients (91.2%), paradoxical septal wall motion in 93 patients (91.2%), the ratio of pulmonary/systemic output was 2.7 +/- 0.6 (range 1.7 to 7.4) and over 2 in 90% of patients: pulmonary systolic pressure was 32.3 +/- 12 mmHg and over 40 mmHg in 18 patients (17.6%). Ninety-four patients were followed up regularly with a mean follow-up time of 5.5 +/- 3.6 years (1-14 years). The right ventricle remained dilated in 37 patients (39.4%) after surgery: the right ventricular dimension decreased from 36 +/- 1 to 27.8 +/- 6.2 mm (p = 0.001). The ratio of end diastolic right ventricular/left ventricular dimension also decreased from 1.07 +/- 0.31 to 0.56 +/- 0.12 (p = 0.0001). Multivariate analysis identified two predictive factors of persistent right ventricular dilatation: age > 40 years (p = 0.009) and a pulmonary/systemic flow ratio > 3 (p = 0.03). Interventricular septal wall motion remained paradoxical in 21 patients (22%). Multivariate analysis identified two predictive factors of persistent paradoxical septal motion: age > 40 years (p = 0.02) and systolic pulmonary pressures > 40 mmHg (p = 0.03). These abnormalities remained asymptomatic in all but two patients with persistent long-term hypertension and a residual atrial septal defect. The persistence of right ventricular dilatation and paradoxical septal motion was quite common, with older age at surgery, systolic pulmonary artery pressure > 40 mmHg and a ratio of pulmonary/systemic blood flow > 3, being predisposing factors. These abnormalities were clinically asymptomatic when isolated.     

Bidirectional shunt in uncomplicated atrial septal defect

The presence of right to left shunts at atrial level in 40 patients with an uncomplicated atrial septal defect was determined by measuring the pulmonary vein to systemic artery oxygen stepdown . In six patients (group 1) a sizeable right to left shunt was found: left atrial oxygen stepdown was greater than or equal to 0.7 vol%, mean right to left shunt 0.67 1/min/m2 (range 0.36-1.0), and arterial oxygen saturation between 84% and 90.5%. The patients in group 1 did not show any differences from those with left to right shunts alone (group 2) as regards sex, cardiac rhythm, heart rate, "a" wave and mean right atrial pressure, end diastolic right ventricular pressure, morphology of diastolic right ventricular pressure curves, pulmonary to systemic vascular resistance ratio, size of the defect, and coexistence of anomalous pulmonary venous drainage. Patients with coexisting right to left shunts were, however, significantly older and had smaller left to right shunts. Thus an appreciable number of patients with uncomplicated atrial septal defects have major right to left shunts which are unrelated to pulmonary hypertension or right heart failure. These shunts may be detected by the usual oximetric techniques and apparently develop with age, which suggests that they result from changes associated with chronic right volume overload.     

The determinants of right ventricular function in patients with atrial septal defect

OBJECTIVE: The purpose of this study was to ascertain the determinants of right ventricular (RV) systolic and diastolic functions in patients with atrial septal defect. METHODS: Thirty-three patients with atrial septal defect having left to right shunt were enrolled in this study. RV function parameters were assessed echocardiographically. RV systolic function was assessed using tricuspid tissue Doppler S velocity (St). With regard to RV diastolic function parameters, E/A ratio, deceleration time (DT), E/Et ratio (Et = tissue Doppler E velocity), RV isovolumetric relaxation time (RVIVRT) were assessed. RV myocardial performance index (MPI) was calculated as an index of both systolic and diastolic function. Pulmonary artery stiffness (PAS) was also calculated. After echocardiography, right and left heart catheterization was performed. Mean pulmonary artery pressure (MPAP), mean right atrial pressure (MRAP), systemic flow (Qs), pulmonary flow (Qp), systemic vascular resistance (SVR), and pulmonary vascular resistance (PVR) were obtained using the data of invasive measurements. RESULTS: In multivariate analysis, MPAP was found to be the parameter closest related to RVIVRT (r = 0.73, p < 0.001) and E/Et (r = 0.66, p < 0.001), while PAS was found to be the parameter closest related to MPI (r = 0.53, p = 0.002). In addition, St velocity was found the only parameter related to PVR (r = -0.39) in univariate analysis. There was no relationship between QP/QS and any of the RV function parameters. CONCLUSION: The pulmonary vascular bed appears to be the predictor of the RV functions in patients with atrial left to right shunts, and the amount of the shunt seems to have no direct adverse influence on the RV functions.     

Analysis of ventricular septal motion by doppler tissue imaging in atrial septal defect and normal heart

The aortic root and the upper part of the ventricular septum moves anteriorly in early systole, while the lower part moves posteriorly. The hinge of the counterpart motion of the ventricular septum is called pivot point. Using Doppler tissue imaging (DTI), we attempted to clarify the location of the pivot point of the ventricular septum in children with normal heart and with atrial septal defect (ASD), and to investigate the relation between the degree of the downward shift of the pivot point and that of volume overload of the right ventricle in patients with ASD. Study subjects consisted of 20 healthy children and 36 patients with ASD, aged from 1 to 15 years (mean 5.7+/-3.4) in the normal group and 6 months to 12 years (mean 4.4+/-3.2) in the ASD group, respectively. The pivot point was designated as a border of the color signal of DTI of the ventricular septum in early systole. Measurements were then obtained on cross-sectional echocardiography and DTI: septal length in the parasternal long-axis view, distance from aortic valve to pivot point in early systole, diastolic left ventricular internal dimension, and diastolic right ventricular internal dimension. In the normal group, the ratio of distance from aortic valve to pivot point/septal length was 0.13+/-0.049, whereas it was 0.26+/-0.168 in the group with ASD (p <0.001). In the ASD group, the distance from aortic valve to pivot point normalized by body surface area (mm/m2) correlated with the ratio of diastolic right/left ventricular internal dimension and with the ratio of pulmonary to systemic flow (Qp/Qs) (r = 0.63 and 0.50, respectively). The ratio of the distance from aortic valve to pivot point/septal length correlated with the ratio of diastolic right/left ventricular internal dimension and Qp/Qs (r = 0.56 and 0.44, respectively). By DTI, the pivot point was located at the upper 13+/-5% of the total length of the ventricular septum in normal children, and was located at 26+/-17% in patients with ASD (p < 0.001). The degree of this displacement in ASD correlated with that of volume overload of the right ventricle. The paradoxic motion of the ventricular septum shown in the ASD could be explained by this downward shift of the pivot point.     

Determination of left to right shunt by thermodilution in patients with ventricular septal defect

A modified thermodilution technique was used to determine the quantity of shunt in patients suffering from congenital heart disease with a left to right shunt. In our modification, the thermistor was placed within the pulmonary artery and an indicator was injected into both sides of the heart. In a series of 33 cardiac catheterizations in children (1-17 years) with ventricular septal defect (VSD), pulmonary blood flow (Qp), systemic blood flow (Qs) and the ratio of Qp to Qs (Qp/Qs) were determined by this and ordinary oximetry (Fick) methods. Correlation coefficients between indexes obtained by these methods were 0.54 (Qp), 0.78 (Qs), and 0.75 (Qp/Qs). The estimates of Qp and Qp/Qs obtained by thermodilution were smaller than those obtained by the Fick method. This modification of thermodilution is simple, rapid, and useful in clinical practice.     

Echocardiographic estimation of a left-to-right shunt in isolated ventricular septal defects

35 infants and children with isolated ventricular septal defects (VSDs) had echocardiographic examination within 24 h of cardiac catheterization. Left atrial to aortic root (LA : Ao) ratio, left atrial internal dimension/meter square body surface area (LAID/m2) and left ventricular internal dimension in diastole/meter square body surface area (LVIDd/m2) were compared with the cardiac catheterization determined pulmonary-to-systemic flow (Qp : Qs) ratio. 35 children with normal cardiovascular findings served as controls. The LA : Ao ratio in the VSD group (1.38 +/- 0.13) was significantly higher than in the control group (1.01 +/- 0.05) (P less than 0.01). Similarly the LAID/m2 and LVIDd/m2 were significantly higher in the VSD group than in the control group (P less than 0.01). Additionally, echographic dimensions were increased in proportion to the elevation of Qp : Qs (r = 0.71--0.73). LA : Ao ratios higher than 1.4 : 1 were generally associated with Qp : Qs ratios greater than 2 : 1. All patients with Qp : Qs greater than 2 : 1 had LA : Ao ratios of 1.4 or higher. This study suggested that echocardiography is a useful noninvasive technique in estimating the Qp : Qs in patients with isolated VSDs, and may serve as an additional clinical parameter in the assessment of patients with VSDs.     

Echocardiographic assessment of left-to-right shunt volume in children with ventricular septal defect.

Echocardiograms were performed in 20 infants and children with isolated ventricular septal defects (VSD) undergoing cardiac catheterization. The magnitude of the left-to-right shunt was expressed as the pulmonary-to-systemic flow ratio (Qp/Os) and was compared to a ratio of the echographic left atrial (LA) diameter to the aortic root (Ao) diameter (LA/Ao). The Qp/Qs was also compared to LA/m2. Thirty-three normal children served as controls. The LA/m2 and Ao/m2 were significantly larger in normal infants under one year of age than in children above one year. The LA/Ao, however, was not influenced by age or size. A strong linear relationship was found between Qp/Qs and the LA/Ao (r = 0.96). The LA/Ao measurement appears to be helpful in the noninvasive assessment of the left-to-right shunt in patients with VSD.     

Assessment of the intracardiac left to right shunts with a single scintillation probe

In order to assess the accuracy of pulmonary time-activity curves obtained at bedside with a single scintillation probe and Technetium-99m-labelled erythrocytes, pulmonary to systemic flow ratio (Qp:Qs) was calculated for radionuclide and hemodynamic investigations in 104 patients with suspected intracardiac left to right shunts. Cardiac catheterization confirmed the presence of shunts in 76 patients. Pulmonary time-activity curve was 100% sensitive, 88% specific, and 96% accurate in detecting the shunt. Correlation between the radionuclide and hemodynamic Qp:Qs was excellent (r = 0.93). Results were classified in four quantitative categories according to the Qp:Qs values. In 76 patients (73%) radionuclide and hemodynamic data fell in the same category. We conclude that radionuclide pulmonary time-activity curves generated with a scintillation probe is a reliable method in quantitative assessment of intracardiac left to right shunts.