Ventricular function in atrial septal defect

Assessment of Diastolic Function in Congenital Heart Disease

Diastolic function is an important component of left ventricular (LV) function which is often overlooked. It can cause symptoms of heart failure in patients even in the presence of normal systolic function. The parameters used to assess diastolic function often measure flow and are affected by the loading conditions of the heart. The interpretation of diastolic function in the context of congenital heart disease requires some understanding of the effects of the lesions themselves on these parameters. Individual congenital lesions will be discussed in this paper. Recently, load-independent techniques have led to more accurate measurements of ventricular compliance and remodeling in heart disease. The combination of inflow velocities and tissue Doppler measurements can be used to estimate diastolic function and LV filling pressures. This review focuses on diastolic function and assessment in congenital heart disease.

Global and regional left ventricular function in patients undergoing transcatheter closure of secundum atrial septal defect

This study sought to evaluate global and regional left ventricular (LV) function before and early after device closure of atrial septal defects (ASDs) in patients with normal pulmonary pressure. Global LV diastolic function was unaffected by ASD closure. An improvement in global LV systolic function at rest resulted in an increase in stroke volume at rest. Nevertheless, total cardiac output did not change after the procedure, because of a decrease in heart rate at rest counterbalancing the increase in stroke volume. Thus, lateral and inferior LV regional systolic function were preserved after device implantation. Moreover, no changes in regional LV diastolic function were highlighted during the study.

Evidence of adverse ventricular interdependence in patients with atrial septal defects

Right ventricular (RV) volume overload is associated with left ventricular (LV) distortion and dysfunction. The availability of transcatheter device closure of secundum atrial septal defect (ASD) provides an ideal model for investigating the immediate effects of elimination of RV volume overload and avoiding the confounding effects of surgery on LV function. Echocardiograms before and after device closure of ASD were analyzed for ejection fraction, percent changes in cross-sectional area and circumference, percent changes in free wall and septal endocardial lengths, and eccentricity. We enrolled 34 patients (median age 9 years) who underwent device closure of ASD (pulmonary to systemic shunt 1.6 +/- 0.4). Ejection fraction and LV end-diastolic volume, reflective of chamber preload, were significantly decreased in the presence of RV volume overload and normalized after defect closure with normalization of LV shape. Altered LV geometry secondary to RV volume overload was associated with regional variation in preload,such that diastolic circumference, a surrogate of myofiber preload, increased after closure of ASD secondary to a small increase in LV free wall arc length in conjunction with a much more significant increase in septal length. Thus, LV dysfunction associated with RV volume overload is secondary to altered chamber geometry and decreased myofiber preload. This physiology is immediately reversible and is independent of heart rate and afterload.

Quantification of shunt volumes in congenital heart diseases using a breath-hold MR phase contrast technique--comparison with oximetry

AIMS

Comparison of breath-hold MR phase contrast technique in the estimation of cardiac shunt volumes with the invasive oximetric technique.

METHODS AND RESULTS

Seventeen patients with various cardiac shunts (10 ASD, 3 VSD, 1 PDA, 3 PFO) and five healthy volunteers were investigated using a 1.5 Tesla system. The mean flow velocity, the mean volume flow and the transverse area in the ascending aorta and the left and right pulmonary artery were measured using the MR phase contrast breath-hold technique (through plane, FLASH 2D-sequence, TR/TE 11/5 ms, phase length 106 ms, VENC 250 cm/s). The ratio of mean flow in the pulmonary (Qp: sum of mean flows in the left and right pulmonary arteries) and the systemic circulation (Qs: mean flow in the ascending aorta) was calculated and compared with invasively measured Qp:Qs ratios. Oximetry was performed within 24 h of the MR investigation. The non-invasive shunt measurement in the 17 patients showed a mean Qp:Qs ratio of 2.00 +/- 0.86. Comparing the MR data with the invasively measured Qp:Qs showed a correlation coefficient of r = 0.91 (p < 0.001).

CONCLUSION

Cardiac shunt volumes can be measured reliably using a shorter acquisition time with breath-hold MR phase contrast technique.

Evaluation of right ventricular systolic pressure during incremental exercise by Doppler echocardiography in adults with atrial septal defect

STUDY OBJECTIVES

Pulmonary hypertension is the most important complication in patients with atrial septal defect (ASD), but its role in limiting exercise has not been examined. This study sought to evaluate exercise performance in adults with ASD and determine the contribution of elevated pulmonary artery pressure in limiting exercise capacity.

DESIGN

We used Doppler echocardiography during exercise in 10 adults (aged 34 to 70 years) with isolated ASD (New York Heart Association class I, II) and an equal number of matched control subjects. Incremental exercise was performed on an electrically braked upright cycle ergometer. Expired gases and VE were measured breath-by-breath. Two-dimensional and Doppler echocardiographic images were obtained at rest prior to exercise to determine ASD size, stroke volume (SV), shunt ratio (Qp:Qs), right ventricular outflow tract (RVOT) size, and right ventricular systolic pressure at rest (RVSPr). Doppler echocardiography was repeated at peak exercise to measure right ventricular systolic pressure during exercise (RVSPex).

RESULTS

Resting echocardiography revealed that RVOT was larger (21+/-4 vs 35+/-8 mm, mean+/-SD; p=0.0009) and RVSPr tended to be higher (17+/-8 vs 31+/-8 mm Hg; p=0.08) in ASD; however, left ventricular SV was not different (64+/-23 vs 58+/-23 mL; p>0.05), compared with control subjects. Despite normal resting left ventricular function, ASD patients had a significant reduction in maximum oxygen uptake (VO2max) (22.9+/-5.4 vs 17.3+/-4.2 mL/kg/min; p=0.005). RVSPex was higher (19+/-8 vs 51+/-10 mm Hg; p=0.001) and the mean RVSP-VO2 slope (1+/-2 vs 18+/-3 mm Hg/L/min; p=0.003) and intercept (17+/-4 vs 27+/-4 mm Hg; p=0.05) were higher in the ASD group. VO2max correlated inversely with both RVSPr (r=-0.69; p=0.007) and RVSPex (r=-0.67; p=0.01).

CONCLUSION

These findings suggest that adults with ASD have reduced exercise performance, which may be associated with an abnormal increase in pulmonary artery pressure during exercise.

Pre- and postoperative exercise capacity associated with hemodynamics in adult patients with atrial septal defect: a retrospective study

OBJECTIVE

This study evaluated the pre- and postoperative exercise capacity in adult patients with atrial septal defect (ASD) associated with hemodynamic variables.

METHODS

Adults (70) with ASD underwent symptom-limited exercise tests. Peak O2 uptake (Peak VO2) and % peak VO2, that is the percentage of predicted value, were measured. These patients were divided into three groups according to pulmonary-to-systemic flow ratio (Qp/Qs) and systolic pulmonary arterial pressure (PAs); Group A: Qp/Qs < or = 3, PAs < or = 50 mm Hg, Group B: Qp/Qs > 3, any PAs, Group C: Qp/Qs < or = 3, PAs > 50 mm Hg. Exercise test was repeated in 22 patients after surgical closure of ASD (mean 4.6 +/- 2.0 months).

RESULTS

Peak VO2 was significantly lower in group B (P < 0.01) and group C (P < 0.01) than in group A (19.3 +/- 5.7, 17.6 +/- 3.6, 27.6 +/- 6.3 ml/min/kg, respectively). In patients except those in group C, there were a weak negative correlation between PAs and % peak VO2 (r = 0.61) and a significant negative correlation between Qp/Qs and % peak VO2 (r = 0.86). Postoperative peak VO2 increased significantly in group A (27.2 +/- 5.1-31.1 +/- 5.1 ml/min/kg, P < 0.05) and group B (16.7 +/- 3.3-21.5 +/- 2.1 ml/min/kg, P < 0.01). However, there was no significant difference between pre- and postoperative peak VO2 in group C (16.8 +/- 1.3-17.8 +/- 2.8 ml/min/kg, NS).

CONCLUSIONS

In ASD patients except those with small or moderate left-to-right shunt and high pulmonary arterial pressure, there was a significant negative correlation between Qp/Qs and peak VO2 corrected by age and gender. Patients with large left-to-right shunt and/or high pulmonary arterial pressure had reduced exercise capacity. However, exercise capacity in patients with large left-to-right shunt increased after closure of ASD regardless of whether they had high pulmonary arterial pressure.

A critical reappraisal of the oximetric assessment of intracardiac left-to-right shunting in adults

Although the oximetric analysis of blood from the right heart chambers is the most commonly used method for assessing the presence of intracardiac left-to-right shunting, the data the analysis is based on are limited. In addition, uncertainty exists concerning the best way of estimating the mixed venous oxygen content in subjects with intraatrial left-to-right shunting. In 102 adults without left-to-right shunting, blood was obtained from the venae cavae and right heart chambers to measure oxygen content. The limits of normality of oxygen content differences were 0.5 ml/dl from venae cavae to right atrium, 0.6 ml/dl from right atrium to right ventricle, and 0.9 ml/dl from right ventricle to pulmonary artery. The pulmonary arterial oxygen content was best estimated by combining the superior and inferior vena caval oxygen contents according to the formula (2[SVC] + 3[IVC]) divided by 5, where SVC is the superior vena cava and IVC is the inferior venae cava. These data provide new oximetric criteria for establishing the presence of intracardiac left-to-right shunting in adults.

Late Surgical Closure of Secundum Type Atrial Septal Defect

Between 1968 and 1995, a total of 153 patients who were between 35 and 63 years of age (mean 49.8 years), underwent surgery for secundum type atrial septal defect. There were 78 (50.9%) males and 75 females (49.1 %). Mean left-to-right shunt ratio was calculated as 2.49. Mean pulmonary artery pressure was 50.15 mm Hg. Three patients died within 30 days of surgery, giving a hospital mortality of 1.96%. Long-term follow-up was available in 135 cases (90%). Total follow-up was 967.3 patient-years and ranged from 3 months to 11.3 years (mean 7.16 years). There were no late deaths reported. Four patients were readmitted with atrial fibrillation and 2 with pericardial effusion. In our experience, surgical closure of atrial septal defect in adults was found to be successful, safe, and with low morbidity in patients with pulmonary hypertension and congestive heart failure.

Doppler echocardiographic evaluation of left ventricular diastolic function after surgical correction of atrial septal defect during childhood

Transmitral flow was studied using Doppler echocardiography with the A/E ratio as a parameter of left ventricular diastolic function in 21 patients (ages 2.5-30.0 years) who had undergone early surgical correction of an isolated secundum type atrial septal defect (ASD) compared to a healthy cohort of 21 subjects. Pre- and postoperative M-mode recordings were compared in 12 of the 21 patients to evaluate the effect of operation on interventricular septal motion (IVS) and left ventricular (LV) and right ventricular (RV) end-diastolic diameter ratio (LVDD/RVDD) as parameters of right ventricular volume overload. No significant difference in A/E ratio was found between the patient and control groups. IVS was shown to normalize in 11 of 12 patients postoperatively and to improve from paradox to flattened in 1 of 12. LVDD/RVDD increased from 1.26 +/- 0.31 to 2.10 +/- 0.51 (p = 0.0008), with no significant difference remaining between the control and patient groups postoperatively. These findings support the conclusion that an intrinsic abnormality of the left ventricle is not responsible for its diastolic dysfunction in patients with ASD who develop left ventricular failure, thereby implicating an acquired abnormality. Mechanical sequelae of right ventricular volume overload were shown to normalize in all patients subsequent to operation in the present study, and therefore cannot be excluded as a cause of left ventricular failure in ASD.

Effect of increase in heart rate on interatrial shunt in atrial septal defect

The effect of increases in heart rate by atrial pacing was investigated in 20 children [mean 9 +/- 4 (SD) years] with atrial septal defect. Systemic blood flow increased by 13 +/- 10 and 27 +/- 22% with a 25 and 50% increase in heart rate, respectively. Pulmonary blood flow, however, remained unaltered. Thus, rapid pacing decreased the pulmonary to systemic blood flow ratio significantly (-15 +/- 10 and -22 +/- 13%, respectively). This hemodynamic alteration was attributed to the difference in diastolic distensibility (compliance) between the left and right ventricles, and the ratio of right ventricular to left ventricular compliance (defined by dV/dP) near the end-diastolic pressure was estimated to be 6.5 +/- 4.2. It is suspected that the increase in heart rate may contribute to the lowering of pulmonary to systemic flow ratio during exercise in children with atrial septal defect.

Interdependence of the left and right ventricles in health and disease

Since the publication of Bernheim's report it has been clear that the anatomic and functional integrity of each ventricle is an important determinant of the functional characteristics of the other ventricle. How the ventricles interact in health and disease has been of interest to many investigators. This article reviews and considers the structure and function of each ventricle as an independent subunit and as a unified pumping system in the healthy state and in various disease states.

Some immediate hemodynamic consequences of closure of atrial septal defects of the secundum type

The circumclusion method for surgical closure of atrial septal defects (ASDs) of the secundum type makes it possible, during surgery, to close and reopen the defect as desired. In each of 23 patients the following statistically significant pressure and flow changes were found when the ASD was closed: increasing mean pressures in the ascending aorta (from 74 to 87 mm Hg), left atrium (from 10 to 18 mm Hg), and right pulmonary artery (from 20 to 24 mm Hg); increasing mean flows in the ascending aorta (from 84 to 111 ml/min/kg); decreasing mean pressures in the right atrium (from 9.0 to 7.7 mm Hg); and decreasing mean flows in the right pulmonary artery (from 78 to 46 ml/min/kg). Surprisingly, no correlation between shunt size determined before and during surgery was found. However, in the calculation of the intraoperative shunt, several factors might have contributed to an erroneous result. In 17 patients a right heart catheterization was performed in the third to thirteenth postoperative month and the following statistically significant changes from the intraoperative results with closed ASD were found: The intraoperative mean pressure in the left atrium (18 mm Hg) decreased to 7.3 mm Hg after surgery (pulmonary wedge pressure), the pulmonary arterial pressure decreased from 23 to 13 mm Hg, and the right atrial pressure from 8.2 to 1.6 mm Hg.

The role of the pericardium in interactions between the cardiac chambers

Distension of one side of the heart involves both the atrium and the ventricle, and such atrioventricular enlargement encroaches more on pericardial volume than would ventricular distension alone. The influence of distension of the entire right side of the heart on the pressure-volume relationship of the entire left heart was studied in six postmortem canine hearts with intact pericardium. The pressure-volume relation of the left heart was determined when the right heart was empty and when it was filled with saline. The pressure-volume curve of the left heart became steeper when the volume of the right heart was increased. However, after subtracting pericardial pressure from the left heart pressure, the pressure-volume curves were unaffected by increased volume of the right heart. Selective distension of the entire right heart has a considerable effect on the filling characteristics of the left heart when the pericardium is intact, although this is less than that observed in experiments in which the more compliant atria have been excluded. This effect becomes negligible after subtracting pericardial pressure.

Ventricular performance in adults after operation for congenital heart disease

Symptomatic ventricular dysfunction in adults who have had reparative operations for the more common congenital heart defects is uncommon. However, both invasive and noninvasive laboratory assessments of ventricular function have revealed abnormalities in some subsets of patients after repair of atrial septal defect, ventricular septal defect, aortic or pulmonary stenosis, tetralogy of Fallot, transposition of the great arteries and tricuspid atresia. Possible causative factors of late ventricular dysfunction after repair include the duration and severity of volume or pressure overload; the duration and severity of cyanosis; intermittent episodes of imbalance between myocardial oxygen supply and demand; residuae, sequelae and complications of treatment; and acquired disease. Further long-term follow-up studies are needed to assess the effect of current methods of therapy as well as timing of operative intervention on ventricular function in adults.

Hemodynamic effects of vasodilator therapy in severe left heart failure combined with large atrial septal defects

Two patients presented with severe left heart failure and large secundum atrial septal defects without severe pulmonary hypertension. The acute hemodynamic effects of two commonly used vasodilator agents, isosorbide dinitrate and hydralazine, are described. Although isosorbide dinitrate improved systemic forward cardiac output, it also increased left-to-right intracardiac shunting in both patients. On the other hand, hydralazine dramatically improved systemic toward output and concomitantly diminished left-to-right shunt flow in each patient (43 and 21 percent). The complexities of combined severe left ventricular failure and a large atrial septal defect with left-to-right shunting, and the importance of extensive hemodynamic monitoring at the time of pharmacologic intervention, are discussed.

Normal left ventricular systolic function in adults with atrial septal defect and left heart failure

Systolic left ventricular contractile function has not been extensively evaluated in patients with atrial septal defect who have symptoms of left-sided congestive heart failure. This study examined left ventricular systolic function hemodynamically and angiographically in 6 such adult patients (Group A), 12 adult patients with atrial septal defect without heart failure (Group B) and 20 normal subjects. The mean ( +/- standard error of the mean) left ventricular end-diastolic pressure was higher in patients in Group A (17 +/- 0.8 mm Hg) than in patients in group B (6.9 +/- 0.6 mm Hg) (p less than 0.001). Both right atrial pressure ( 11 +/- 1.3 versus 4.9 +/- 0.5 mm Hg) (p less than 0.001) and mean pulmonary arterial pressure (30 +/- 1.8 versus 15 +/- 1 mm Hg) were also higher in Group A than in Group B. Left ventricular cardiac index and stroke work index did not differ in the two groups. Variables of left ventricular systolic function were similar in both groups of patients and in normal subjects: Ejection fraction was 0.71 +/- 0.05 in Group A, 0.74 +/- 0.02 in Group B and 0.74 +/- 0.01 in normal subjects. Velocity of circumferential shortening was 1.38 +/- 0.14 circumferences/s in Group A, 1.38 +/- 0.07 circumferences/s in Group B and 1.27 +/-0.04 circumferences/s in normal subjects. There was no difference in left ventricular contractile function as indicated by the ratio of end-systolic wall stress to end-systolic volume index among the three groups: normal subjects, average 5.6 +/- 0.19 versus 6.1 +/- 0.5 in Group B and 6.0 +/- 0.6 dynes X 10(3)/cm(2)/(ml/m(2) in Group A. This study of patients with atrial septal defect and left heart failure indicates that abnormal left ventricular systolic contractile function is probably not the cause of the symptoms and elevated left heart filling pressures observed in this group. An abnormality in left ventricular diastolic filling, perhaps related to the volume loaded right ventricle, may explain these changes.

Radionuclide ventriculography: a noninvasive method for the detection and quantification of left-to-right shunts in atrial septal defect

The present investigation was undertaken to assess a new scintigraphic method for the diagnosis of left-to-right shunts due to atrial septal defect based on the differing stroke volumes of left and right ventricles and to compare it with oxymetric data. Radionuclide ventriculography was carried out after injection of 20 mCi 99mtechnetium-labeled red blood cells. Time-activity curves were obtained from the left and right ventricular regions, and the ratio (A) of end-diastolic-end-systolic count rate differences for the left and right ventricles was calculated. The left-to-right shunt (in percent of the pulmonary flow rate) is then given as 100 X (1 - A/1.43; 1.43 being the previously determined mean value of A in 66 normal patients. In 16 patients with an atrial septal defect and/or partial anomalous pulmonary venous connection a correlation of r = 0.81 was found between those shunts determined by the scintigraphic method and those calculated by oxymetric data. The specificity of the method and the sensitivity in detecting left-to-right shunts exceeding 30% are high. The method is practical and already widely used for determination of ejection fraction end-diastolic volume and other factors. The combination of this technique with other methods for shunt diagnosis such as gamma-fit analysis may prove of special value.

Diastolic bulging of the interventricular septum toward the left ventricle. An echocardiographic manifestation of negative interventricular pressure gradient between left and right ventricles during diastole

Diastolic bulging of the interventricular septum (IVS) toward the left ventricle was observed by real-time cross-sectional echocardiography in three patients with primary pulmonary hypertension and one patient with secondary pulmonary hypertension after closure of an atrial septal defect. M-mode echocardiography showed a characteristic abnormal pattern of septal motion in diastole and in systole. In two patients, we attempted to correlate M-mode motion to the interventricular pressure gradient. During diastole, the interventricular pressure gradient between the left and right ventricles was negative and the pressure gradient curve was very similar to the M-mode echogram of the IVS. Banding studies in which acute right ventricular hypertension was produced in dogs showed similar shape changes, suggesting that the diastolic shape and motion of the septum are determined by the interventricular pressure gradient between the ventricles. Diastolic bulging of the IVS toward the left ventricle in our patients results from negative interventricular pressure gradient between the left and right ventricles during diastole.

Assessment of left ventricular function in secundum atrial septal defect by computer analysis of the M-mode echocardiogram

Left ventricular function in 53 patients with secundum atrial septal defect was assessed by computer-assisted analysis of the left ventricular echocardiogram and by cardiac catheterization. The patients were divided into two groups, those younger and those older than 60 years, to investigate the effect of aging on left ventricular function. Cavity size was significantly smaller than normal (p less than 0.01) and septal motion was abnormal in 86%, but values for cardiac index, left ventricular end-diastolic pressure, velocity of circumferential fiber shortening, left ventricular filling rate, and duration of rapid filling were normal in both groups. Regional dynamics assessed in terms of peak rates of systolic thickening and diastolic thinning of the septum and posterior wall were also normal in both groups. We concluded that, although left ventricular minor dimensions are small, and septal motion is reversed in the majority of patients with atrial septal defect, left ventricular function is normal, and it does not appear to deteriorate with increased age, pulmonary hypertension, or the presence of right ventricular failure. The abnormal septal motion appears to be compensated for by enhanced septal and posterior wall percentage thickening.

Secundum atrial septal defect and significant mitral regurgitation: incidence, management and morphologic basis

To better understand the association between mitral regurgitation and secundum atrial septal defect and to clarify the evaluation and management of these patients, the records of 235 adult patients with atrial septal defect were reviewed. Ten patients (4 percent) had significant mitral regurgitation defined by clinical, hemodynamic and angiographic criteria. Three patients required mitral valve replacement at the time of closure of the atrial septal defect and four patients had closure alone, one of whom required mitral valve replacement after five years. Three patients did not undergo closure of the atrial septal defect or mitral valve replacement because of severe coexisting medical problems. In six patients, the mitral valves were studied pathologically and all had thick, fibrotic leaflets and short, thick, fibrotic chordae tendineae. Three of these valves also had scattered areas of patchy myxomatous degeneration and three had areas of vascular ingrowth suggestive of rheumatic disease. Although both invasive and noninvasive studies have high-lighted the coincidence between atrial septal defect and mitral regurgitation, particularly the frequent association of mitral valve prolapse, our data indicate that this association rarely has clinical significance. Furthermore, the morphologic basis for mitral regurgitation in patients with atrial septal defect consists of leaflet and chordal thickening fibrosis and deformity rather than attenuation and ballooning as would be expected in mitral valve prolapse.

Pre and postoperative ventricular function in infants and children with right ventricular volume overload

Hemodynamic and ventricular volume parameters were evaluated in 21 patients (24 studies) with total anomalous pulmonary venous return (TAPVR), 11 patients with secundum atrial septal defect (ASD), and eight patients who had complete correction of TAPVR or ASD. Right and left ventricular (RV and LV) volume parameters were calculated according to Simpson's rule and the area length methods, respectively. In infants with TAPVR, RV end-diastolic volume was larger than normal, but RV ejection fraction was significantly less than normal. LV end-diastolic volume and LV ejection fraction were all less than normal in infants with or without pulmonary hypertension, and the values did not correlate with the cardiorespiratory symptoms. In children with TAPVR or ASD, RV end-diastolic volume and output were higher than normal preoperatively and decreased to normal or near normal values postoperatively. The data suggest that pulmonary venous obstruction and/or RV failure are responsible for cardiorespiratory symptoms in infants with TAPVR and early surgical intervention is recommended in these patients.

Afterload reduction in the management of postinfarction ventricular septal defect

The primary goal in the medical management of ventricular septal defect complicating myocardial infarction is to support cardiac function and control symptoms, if possible, for a period of 4 to 6 weeks. If the patient survives this period, surgical correction of the defect is technically easier and safer. In many cases, However, cardiac function is severly compromised, intractable biventricular failure develops,early operation is necessary and the likelihood of successful repair is diminished.

Mechanism of abnormal septal motion in patients with right ventricular volume overload: a cross-sectional echocardiographic study

To evaluate the mechanism of paradoxical septal motion in patients with right ventricular volume overload (RVVO), short axis cross-sectional, echocardiographic studies of the left ventricle (LV) and interventricular septum (IVS) were performed in 19 patients with paradoxical septal motion due to RVVO and in 20 normal subjects. Short axis study in normal subjects revealed the left ventricle to be a relatively circular structure during both diastole and systole. In patients with RVVO a change in LC diastolic shape was observed. This change in shape varied from a slight flattening of the LV and IVS during diastole to total reversal of the normal direction of septal curvature such that the IVS became concave toward the RV and convex toward the LV. During systole the LV and IVS returned to their normal relatively circular configuration. This change in LV shape from diastole to systole resulted in net motion of the IVS toward the right ventricle (paradoxically). This study therefore suggests that paradoxical septal motion in patients with right ventricular volume overload is a result of a change in the diastolic shape of the left ventricle.

Occult atrial septal defect in adults

Two patients are described who presented with congestive heart failure and were found to have an atrial septal defect with a pulmonary blood flow approximately twice the systemic blood flow. Most of the usual clinical signs of atrial septal defect were absent, and the diagnosis was established by right heart catheterization and radioisotopic angiography. Both patients had hypertension and coronary artery disease. Atrial septal defect in the adult patient may not be recognized because of associated cardiac disease, including coronary artery disease and hypertension, or pulmonary disease which may obscure the usual clinical signs of a septal defect. Radioisotopic angiography and right heart catheterization should be considered in any patients with heart disease or congestive failure of obscure cause even if the usual diagnostic signs of atrial septal defect are absent.

Abnormalities of left ventricular function and geometry in adults with an atrial septal defect. Ventriculographic, hemodynamic and echocardiographic studies

Left ventricular function and motion in 12 adults with an ostium secundum atrial septal defect were analyzed utilizing biplane cineangiography. Values for left ventricular end-diastolic volume index, stroke volume index, ejection fraction, left ventricular end-diastolic pressure and mean rate of circumferential fiber shortening were compared with values in an age-matched group of 11 normal subjects. Comparisons of ventriculographic and echocardiographic data were also made in 5 patients and 10 control subjects. Cardiac index was smaller in patients than in the normal subjects (3.6 vs. 4.5 liters/min per m2, P less than 0.01). Although left ventricular end-diastolic pressure was similar (8 mm Hg in both groups), the end-diastolic volume index was significantly smaller in patients than in normal subjects (56 vs. 76 ml/m2, P less than 0.05). Stroke volume index was also significantly smaller in patients (40 vs. 52 ml/m2, P less than 0.01). The two groups had similar values for ejection fraction (65 +/- 2 percent [standard error of the mean] in patients vs. 68 +/- 2 percent in normal subjects), circumferential fiber shortening velocity (1.67 +/- 0.13 vs. 1.81 +/- 0.15 circumferences/sec.), heart rate (91 +/- 7 vs. 90 +/- 5 beats/min) and mean systemic arterial pressure (92 +/- 5 vs. 87 +/- 3 mm Hg). Early systolic bulging of the upper ventricular septum toward the right ventricle was seen in 10 of 12 patients with an atrial septal defect but in no normal subject. Echocardiographic data supported these findings. No other abnormalities of motion were consistently noted. It is concluded that the left ventricle of patients with an atrial septal defect is subnormal in volume and abnormal in sequence of contraction of the septum and is characterized by apparent decreased distensibility.

Cardiac performance during pregnancy: serial evaluation using external systolic time intervals

Indirect systolic time indices were used to evaluate serial changes in left ventricular function during pregnancy in 13 normal patients and five patients with compensated cardiac conditions. Changes in both groups tended to parallel each other. In both groups, serial LVET index decreased, PEP index increased, and PEP/LVET ratio increased. Q-S2 index decreased in the normal group in midpregnancy and was inconsistent in the cardiac group. In the immediate postpartum period, LVET index returned to baseline values but PEP and PEP/LVET remained increased in both groups. Results of multiple comparison tests demonstrated that the largest (or smallest) value of each systolic time interval during pregnancy was observed in either the periods of the weeks 28 to 34 or 34 to 38. No significant differences were noted in intergroup comparison between the normal and cardiac groups. These data suggest that consistent changes in cardiac function may be determined during pregnancy by the noninvasive technique of indirect systolic time interval evaluation. These changes may reflect a change in left ventricular contractility, preload or afterload. The differences may persist even in the immediate postpartum period when cardiac output and heart rate have decreased to normal, suggesting residual changes in intrinsic left ventricular function. In patients with compensated heart disease, indirect tests of left ventricular function generally reflect the changes in normal pregnant women.