Mechanics of the single left ventricle: a study in ventricular-ventricular interaction II

Double-Outlet Right Ventricle With Intact Ventricular Septum and Left Atrioventricular Valve Regurgitation in a Patient With Right Atrial Isomerism

We present a very rare case of right atrial isomerism, double-outlet right ventricle, and incomplete atrioventricular septal defect (intact ventricular septum). In the neonatal period, the right ventricle was compressed by a "blind-ended" left ventricle with mild-to-moderate left atrioventricular valve regurgitation. The regurgitation gradually decreased from mild-to-moderate to mild with body weight gain. The patient underwent systemic-to-pulmonary shunt at three months of age and bilateral bidirectional Glenn at eight months of age. Although the echocardiogram demonstrated that the right ventricle was still compressed by the left ventricle, over time the size of the left ventricle reduced significantly and the left atrioventricular valve regurgitation became trivial.

Single Ventricular Torsional Mechanics After Fontan Palliation and Their Impact on Outcomes

Background

Abnormal left ventricular (LV) rotational mechanics in biventricular hearts are associated with adverse outcomes; however, these are less well characterized for hearts with functionally single ventricles.

Objectives

The purpose of this study was to characterize ventricular rotational mechanics in the Fontan circulation and their relationship to outcomes.

Methods

Single-center, retrospective analysis of magnetic resonance examinations for 329 Fontan patients (15 [IQR: 10-21] years) and 42 controls. The ventricular cine short-axis stack was analyzed to derive torsion metrics. Torsion calculated as the difference between apical and basal rotation normalized to ventricular length.

Results

Fontan patients had higher indexed ventricular end-diastolic volume (97 mL/body surface area1.3 vs 72 mL/body surface area1.3), lower ejection fraction (53% vs 60%), and lower proportion of basal clockwise rotation (62% vs 93%), apical counterclockwise rotation (77% vs 95%), and positive torsion (82% vs 100%); P < 0.001 for all. A composite outcome of death or heart transplant-listing occurred in 31 (9%) patients at a median follow-up of 3.9 years. Torsion metrics were associated with the outcome; although, on multivariate analysis only right ventricular (RV) morphology and indexed ventricular end-diastolic volume were independently associated. LVs with negative torsion, and RVs regardless of torsional pattern, had worse outcomes compared to LVs with positive torsion (P = 0.020).

Conclusions

Single ventricles in a Fontan circulation exhibit abnormal torsional mechanics, which are more pronounced for RV morphology. Abnormal torsion is associated with death or need for heart transplantation. Fontan patients with LV morphology and preserved torsion exhibit the highest transplant-free survival and torsion may offer incremental prognostic data in this group of patients.

Automated segmentation of long and short axis DENSE cardiovascular magnetic resonance for myocardial strain analysis using spatio-temporal convolutional neural networks

BACKGROUND

Cine Displacement Encoding with Stimulated Echoes (DENSE) facilitates the quantification of myocardial deformation, by encoding tissue displacements in the cardiovascular magnetic resonance (CMR) image phase, from which myocardial strain can be estimated with high accuracy and reproducibility. Current methods for analyzing DENSE images still heavily rely on user input, making this process time-consuming and subject to inter-observer variability. The present study sought to develop a spatio-temporal deep learning model for segmentation of the left-ventricular (LV) myocardium, as spatial networks often fail due to contrast-related properties of DENSE images.

METHODS

2D + time nnU-Net-based models have been trained to segment the LV myocardium from DENSE magnitude data in short- and long-axis images. A dataset of 360 short-axis and 124 long-axis slices was used to train the networks, from a combination of healthy subjects and patients with various conditions (hypertrophic and dilated cardiomyopathy, myocardial infarction, myocarditis). Segmentation performance was evaluated using ground-truth manual labels, and a strain analysis using conventional methods was performed to assess strain agreement with manual segmentation. Additional validation was performed using an externally acquired dataset to compare the inter- and intra-scanner reproducibility with respect to conventional methods.

RESULTS

Spatio-temporal models gave consistent segmentation performance throughout the cine sequence, while 2D architectures often failed to segment end-diastolic frames due to the limited blood-to-myocardium contrast. Our models achieved a DICE score of 0.83 ± 0.05 and a Hausdorff distance of 4.0 ± 1.1 mm for short-axis segmentation, and 0.82 ± 0.03 and 7.9 ± 3.9 mm respectively for long-axis segmentations. Strain measurements obtained from automatically estimated myocardial contours showed good to excellent agreement with manual pipelines, and remained within the limits of inter-user variability estimated in previous studies.

CONCLUSION

Spatio-temporal deep learning shows increased robustness for the segmentation of cine DENSE images. It provides excellent agreement with manual segmentation for strain extraction. Deep learning will facilitate the analysis of DENSE data, bringing it one step closer to clinical routine.

Diastolic Cardiac Function by MRI-Imaging Capabilities and Clinical Applications

Most cardiac studies focus on evaluating left ventricular (LV) systolic function. However, the assessment of diastolic cardiac function is becoming more appreciated, especially with the increasing prevalence of pathologies associated with diastolic dysfunction like heart failure with preserved ejection fraction (HFpEF). Diastolic dysfunction is an indication of abnormal mechanical properties of the myocardium, characterized by slow or delayed myocardial relaxation, abnormal LV distensibility, and/or impaired LV filling. Diastolic dysfunction has been shown to be associated with age and other cardiovascular risk factors such as hypertension and diabetes mellitus. In this context, cardiac magnetic resonance imaging (MRI) has the capability for differentiating between normal and abnormal myocardial relaxation patterns, and therefore offers the prospect of early detection of diastolic dysfunction. Although diastolic cardiac function can be assessed from the ratio between early and atrial filling peaks (E/A ratio), measuring different parameters of heart contractility during diastole allows for evaluating spatial and temporal patterns of cardiac function with the potential for illustrating subtle changes related to age, gender, or other differences among different patient populations. In this article, we review different MRI techniques for evaluating diastolic function along with clinical applications and findings in different heart diseases.

The presence of an additional ventricular chamber does not change the outcome of Fontan circulation: a comparative study

OBJECTIVES

The role of an additional ventricle in patients with a functional single ventricle undergoing the Fontan operation has been debated due to conflicting data. Our goal was to report our experience with Fontan circulation for complex congenital heart disease, with a focus on the influence that an additional ventricular chamber may have on early and long-term clinical outcomes.

METHODS

We performed a retrospective clinical study including all patients undergoing the Fontan procedure between 1978 and 2019. Clinical data were retrieved from our institutional database. A 'biventricular' Fontan (BVF) was defined as that performed in a patient with single ventricle anomaly where an additional diminutive ventricular cavity was present at echocardiographic evaluation.

RESULTS

A total of 210 consecutive patients with functional single ventricle were included. Among these, 46 had BVF (21.9%). Early complications occurred in 42 patients (20.0%; 11 in BVF vs 31 in univentricular Fontan; P = 0.53) There were 18 early deaths (8.6%) with no difference between the groups. At a median follow-up of 12.7 years (interquartile range 5.4-20.7), there were no significant differences in late mortality, whereas cardiac rhythm disturbances resulted more frequently in univentricular Fontan (P = 0.018). Statistical analysis showed an equal distribution of BVF across time (P = 0.620), and there were no significant differences in terms of early and late survival (P = 0.53 and P = 0.72, respectively) or morbidity (P = 0.45 and P = 0.80, respectively).

CONCLUSIONS

A secondary ventricle in Fontan circulation is not significantly related to any clinical disadvantage in terms of survival or onset of complications. However, the immediate postoperative course may be influenced negatively by the presence of an additional secondary ventricle.

Heart failure in single right ventricle congenital heart disease: physiological and molecular considerations

Because of remarkable surgical and medical advances over the past several decades, there are growing numbers of infants and children living with single ventricle congenital heart disease (SV), where there is only one functional cardiac pumping chamber. Nevertheless, cardiac dysfunction (and ultimately heart failure) is a common complication in the SV population, and pharmacological heart failure therapies have largely been ineffective in mitigating the need for heart transplantation. Given that there are several inherent risk factors for ventricular dysfunction in the setting of SV in addition to probable differences in molecular adaptations to heart failure between children and adults, it is perhaps not surprising that extrapolated adult heart failure medications have had limited benefit in children with SV heart failure. Further investigations into the molecular mechanisms involved in pediatric SV heart failure may assist with risk stratification as well as development of targeted, efficacious therapies specific to this patient population. In this review, we present a brief overview of SV anatomy and physiology, with a focus on patients with a single morphological right ventricle requiring staged surgical palliation. Additionally, we discuss outcomes in the current era, risk factors associated with the progression to heart failure, present state of knowledge regarding molecular alterations in end-stage SV heart failure, and current therapeutic interventions. Potential avenues for improving SV outcomes, including identification of biomarkers of heart failure progression, implications of personalized medicine and stem cell-derived therapies, and applications of novel models of SV disease, are proposed as future directions.

Practical Guide to Evaluating Myocardial Disease by Cardiac MRI

OBJECTIVE. A spectrum of pathophysiologic mechanisms can lead to the development of myocardial disorders including ischemia, genetic abnormalities, and systemic disorders. Cardiac MRI identifies different myocardial disorders, provides prognostic information, and directs therapy. In comparison with other imaging modalities, cardiac MRI has the advantage of allowing both functional assessment and tissues characterization in a single examination without the use of ionizing radiation. Newer cardiac MRI techniques including mapping can provide additional information about myocardial disease that may not be detected using conventional techniques. Emerging techniques including MR spectroscopy and finger printing will likely change the way we understand the pathophysiology mechanisms of the wide array of myocardial disorders. CONCLUSION. Imaging of myocardial disorders encompasses a large variety of conditions including both ischemic and nonischemic diseases. Cardiac MRI sequences, such as balanced steady-state free precession and late gadolinium enhancement, play a critical role in establishing diagnosis, determining prognosis, and guiding therapeutic management. Additional sequences-including perfusion imaging, T2*, real-time cine, and T2-weighted sequences-should be performed in specific clinical scenarios. There is emerging evidence for the use of mapping in imaging of myocardial disease. Multiple other new techniques are currently being studied. These novel techniques will likely change the way myocardial disorders are understood and diagnosed in the near future.

Strain and Rotational Mechanics in Children With Single Left Ventricles After Fontan

BACKGROUND

Left ventricular (LV) mechanics in patients with different single morphologic LV subtypes, including tricuspid atresia, double-inlet left ventricle, and pulmonary atresia with intact ventricular septum, remain poorly studied. Given that histologic studies indicate differences in LV myocardial fiber orientation, we hypothesized that this may result in altered LV mechanics. The aim of this study was to evaluate the influence of LV morphology on LV mechanics.

METHODS

Fifty-two children with single left ventricles after Fontan operation and age-matched control subjects were prospectively enrolled. Using two-dimensional speckle-tracking echocardiography, longitudinal strain was measured in the four-, three-, and two-chamber long-axis planes, and circumferential strain was measured at the basal, mid, and apical short-axis planes. Apical and basal rotation were measured, and twist and torsion were calculated. We compared strain and rotational mechanics in cases versus control subjects and among LV subtypes.

RESULTS

Compared with control subjects, subjects with single left ventricles had similar LV end-diastolic dimensions but significantly decreased ejection fractions. The single left ventricle cohort had normal global longitudinal strain (P = .20) but lower basal mean circumferential strain (P < .0001). Single left ventricle subjects had higher apical rotation (P = .0001) but decreased basal rotation (P = .0007); there was no difference in twist but increased torsion (P = .001). LV subtypes had different four-chamber (P = .01), two-chamber (P = .006), and global longitudinal strain (P = .01), lowest in the pulmonary atresia with intact ventricular septum subtype.

CONCLUSIONS

Longitudinal LV strain was preserved in children with single left ventricles after Fontan. A pattern of reduced basal circumferential strain and rotation with an increase in apical rotation and torsion in the single left ventricle cohort may be related to differences in myofiber orientation, increased fibrosis, and the impact of altered loading conditions throughout palliation. Decreased longitudinal strain in the pulmonary atresia with intact ventricular septum group may also reflect detrimental interventricular interactions.

Ventricular Torsion in Young Patients With Single-Ventricle Anatomy

BACKGROUND

In normal left ventricles, clockwise basal rotation and counterclockwise apical rotation result in systolic torsion. Torsion is important for contractile efficiency and may be especially important in single-ventricle (SV) physiology. However, little is known about torsion in patients with SVs. The aim of this study was to measure torsion in SVs and to determine its relationship with other measures of ventricular function. The hypothesis was that torsion would be decreased in all SVs, most significantly in single right ventricles, and that it would correlate with other measures of ventricular function.

METHODS

A prospective cross-sectional study was performed in 61 patients with SVs undergoing pre- or post-Fontan cardiac catheterization and 30 matched control subjects. Echocardiography, catheterization, and cardiac magnetic resonance imaging were performed under the same anesthetic. Torsion and strain were measured using speckle-tracking echocardiography. Intracardiac pressures, pulmonary vascular resistance, and cardiac magnetic resonance imaging-derived ventricular volume and ejection fraction were measured.

RESULTS

Thirty-five patients were left ventricular dominant, 15 were right ventricular dominant, 10 were codominant, and one had indeterminate morphology. Thirty-seven patients were pre-Fontan and 24 were post-Fontan. Patients with SVs had similar overall torsion as control subjects (median, 1.7°/cm vs 1.65°/cm; P = NS); however, they had decreased or reversed basal rotation (-0.32°/cm vs -0.93°/cm, P < .0001) and increased apical rotation (1.45°/cm vs 1.06°/cm, P = .0065). There were no differences on the basis of ventricular dominance or palliative stage. Torsion did not significantly correlate with other echocardiographic, catheter-based, or cardiac magnetic resonance imaging measures of cardiac function.

CONCLUSIONS

Single left and right ventricles exhibit preserved torsion, mainly because of preserved or increased apical rotation. Possible mechanisms of torsion in single right ventricles include myofiber remodeling and altered ventricular-ventricular interactions. Understanding myocardial deformation in SVs will improve the ability to interpret ventricular function in this precarious population.

Fibrotic infarction on the LV free wall may alter the mechanics of healthy septal wall during passive filling

The effect of myocardial infarction on the global functioning of the heart is well known. Less is understood regarding the effect of LV fibrotic infarction on the cardiac mechanics of the septal wall. To determine this unknown, the stress and strain of septal wall on the healthy and infarcted rat heart model is measured by using finite element models of rat heart geometries. The main objective of this study was to utilized computational methods to study the effect of LV free wall fibrotic infarction on the healthy septal wall. Three-dimensional biventricular rat heart geometries were developed from cardiac magnetic resonance images of a healthy heart and a heart with left ventricular (LV) fibrotic infarction after infarct induction. From these geometries, FE models were established. Three-dimensional biventricular rat heart geometries developed from cardiac magnetic resonance images were used in creating FE models of healthy and infarcted rat hearts. The average radial strain percentage change of the healthy septal wall on the epicardium, mid-wall and endocardium was 61%, 52% and 14% higher than the infarcted septal wall, respectively. It was concluded that the fibrotic infarction has a potential cause the malfunction of the heart due to high myocardial stress and strain that the septal wall experiences.

Cardiac Magnetic Resonance Feature Tracking Biventricular Two-Dimensional and Three-Dimensional Strains to Evaluate Ventricular Function in Children After Repaired Tetralogy of Fallot as Compared with Healthy Children

Cardiac magnetic resonance imaging is an important tool to evaluate cardiac anatomy and ventricular size and function after repaired tetralogy of Fallot. Magnetic resonance tissue tagging is the gold standard for evaluation of myocardial strain. However, myocardial tagging strain requires tagged images to be obtained prospectively, during the scan and with limited temporal resolution. Cardiac magnetic resonance feature tracking is a new tool that allows the retrospective analysis of cine images. There is limited experience with cardiac magnetic resonance feature tracking strain analysis in children. The medical records of patients with repaired tetralogy of Fallot that had a cardiac magnetic resonance (CMR) study from December 2013 to June 2015 were reviewed. The control group included patients who underwent a CMR with normal cardiac anatomy and ventricular function. Global longitudinal, circumferential and radial strain parameters (2D and 3D) were obtained by retrospectively contouring cine images from ventricular short axis, two chamber and four chamber views using post-processing software (Circle CVi⁴², Calgary, Canada). The correlation between conventional ventricular function parameters and ventricular strain was performed using Pearson's correlation. The mean age of tetralogy of Fallot and control subjects was 12.4 and 14.1 years, respectively. In patients after repaired tetralogy of Fallot, the mean left ventricular global 2D and 3D circumferential strains were -17.4 ± 2.9 and -10.1 ± 3, respectively. The mean indexed right ventricular end-diastolic volume was 135.4 cc m² ± 46 compared to 75.7 cc m² ± 17 in control subjects (P = 0.0001, CI 95%). Left ventricular global circumferential 3D strain showed a statistically significant difference in patients after TOF repair compared to normal subjects (-10.1 ± 3 vs. -14.71 ± 1.9, P = 0.00001). A strong correlation between left ventricular global circumferential 3D strain and right ventricular end-diastolic volume (P ≤ 0.0001) was noted. We found a strong correlation between left ventricular circumferential 3D strain and indexed right ventricular end-diastolic volume, as well as a strong correlation between left ventricular longitudinal 2D strain and right ventricular ejection fraction. Circumferential 3D strain may be a suitable tool to detect early abnormalities of ventricular myocardium even before the ejection fraction becomes compromised. Large-scale prospective studies are recommended.

Clinical-Physiological Considerations in Patients Undergoing Staged Palliation for a Functionally Single Ventricle

OBJECTIVES

The objectives of this review are to discuss the pathophysiology of the circulation with a functionally univentricular heart, with a focus on the unique physiologic characteristics, which provide the underpinnings for the management of these complex patients.

DATA SOURCE

MEDLINE and PubMed.

CONCLUSIONS

The circulation of the patient with a functionally univentricular heart displays unique physiologic characteristics, which are quite different from those of the normal biventricular circulation. There are profound differences within the heart itself in terms of ventricular function, interventricular interactions, and myocardial architecture, which are likely to have significant implications for the efficiency of ventricular ejection and metabolism. The coupling between the systemic ventricle and the aorta also displays unique features. The 3D orientation of the Fontan anastomosis itself can profoundly impact cardiac output, although the "portal" pulmonary arterial bed is a crucial determinant of overall cardiovascular function. As a result, disease-specific approaches to improve cardiovascular function are required at all stages during the care of these complex patients.

Improved Exercise Performance in Patients With Tricuspid Atresia After the Fontan-Björk Modification With Pulsatile Systolic Pulmonary Flow

BACKGROUND

After the Fontan-Björk modification for tricuspid atresia, some patients show pulsatile systolic pulmonary flow. We compared the hemodynamic findings and the clinical presentation of patients with and without pulsatile systolic flow after atrioventricular connection.

METHODS

According to the pulmonary flow pattern by pulsed-wave Doppler assessment of transthoracic echocardiography, 41 patients after atrioventricular connection were divided into two groups: patients who showed dominant pulsatile systolic pulmonary flow (group P, n = 11), and patients who did not (group N, n = 30).

RESULTS

Mean follow-up time was 27.8 ± 4.7 years in group P and 25.3 ± 3.8 years in group N (p = 0.1). Patients in group P had significantly less frequently catheter ablation procedures for tachyarrhythmia (9% versus 50%, p = 0.03). No patient in group P had had cardiac decompensation, whereas 7 patients (23%) in group N had had an episode of cardiac decompensation (p = 0.08). Cardiopulmonary exercise testing revealed that patients in group P showed higher oxygen uptake compared with patients in group N (25.0 ± 7.3 versus 19.6 ± 6.0 mL · kg(-1) · min(-1), p = 0.03). Patients in group P showed higher systolic pulmonary artery pressure (21.3 ± 8.4 versus 16.8 ± 4.5 mm Hg, p = 0.05), higher right ventricular end-diastolic volume index (88.6 ± 30.2 versus 50.3 ± 28.5 mL · L(-1) · m(-2), p = 0.03), and higher right ventricle to left ventricle ratio of end-diastolic volume index (1.4 ± 0.6 to 0.7 ± 0.3, p = 0.01).

CONCLUSIONS

Patients with pulsatile systolic flow in the pulmonary artery had better hemodynamic and better exercise performance compared with patients without pulsatile systolic flow after atrioventricular connection. A sufficient volume and function of the right ventricle is a prerequisite to create pulsatile systolic flow.

Factors associated with in utero demise of fetuses that have underlying cardiac pathologies

Factors associated with in utero fetal demise (IUFD) of fetuses that have underlying cardiac pathologies are largely unknown. This case-control study aimed to define the prevalence of IUFD in fetuses with a diagnosis of cardiac pathologies and to identify prenatal predictors of IUFD. Between January 2004 and December 2010, 74 IUFD cases [4.6 %; 95 % confidence interval (CI) 3.7-5.8 %] were identified from 1,584 cases with a diagnosis of structural or functional cardiac lesions in the Hospital for Sick Children database. The cases were divided into right-sided (N = 28), left-sided (N = 23), great artery (N = 8), and miscellaneous (N = 15) groups. The control subjects (1:1 ratio) were fetuses that had cardiac pathology diagnosed within 48 h of the IUFD case. Multivariable regression models were used to determine echocardiographic predictors of IUFD. The prevalence of IUFD was greatest in hypertrophic cardiomyopathy (8/16, 50 %) and Ebstein's anomaly/tricuspid dysplasia (4/15, 27 %) and lowest in transposition of the great arteries (2/85, 1 %). The findings showed IUFD to be associated with hydrops in 17 (23 %) of the 74 cases and arrhythmia in 11 (15 %) of the 74 cases. The factors identified by univariable logistic regression analyses were right ventricular dysfunction [odds ratio (OR) 2.7; p = 0.001], left ventricular dysfunction (OR 1.8; p = 0.007), umbilical vein pulsations (OR 10.9; p = 0.002), and abnormal ductus venosus flow (OR 3.3; p = 0.01). The factors associated with IUFD in multivariable logistic regression models were cardiomegaly (OR 5.6; p = 0.01), hydrops (OR 29.5; p = 0.001), pericardial effusion (OR 4.1; p = 0.06), and extracardiac abnormalities (OR 7.2; p < 0.001). The prevalence of IUFD is greatest in conditions affecting the ventricular myocardium. The onset of IUFD appears to be related initially to right ventricular dysfunction. Closer surveillance is recommended for lesions at risk of IUFD.

Comparison of pressure-volume loop and echocardiographic measures of diastolic function in patients with a single-ventricle physiology

Echocardiographic measurements of diastolic function have not been validated against invasive pressure-volume loop (PVL) analysis in the single-ventricle population. The authors hypothesized that echocardiographic measures of diastolic function would correlate with PVL indices of diastolic function in patients with a single-ventricle physiology. The conductance-derived PVL measures of diastolic function included the isovolumic relaxation time constant (τ), the maximum rate of ventricular pressure decline (peak -dP/dt), and a measure of passive diastolic stiffness (μ). The echocardiographic measures included Doppler inflow patterns of the dominant atrioventricular valve (DAVV), tissue Doppler velocities (TDI) at the lateral (ventricular free wall) component of the DAVV annulus, and the TDI-derived isovolumic relaxation time (IVRT'). The correlation between PVL and echocardiographic measures was examined. The study enrolled 13 patients at various stages of surgical palliation. The median age of the patients was 3 years (range 3 months to 19 years). τ correlated well with Doppler E:A (r = 0.832; p = 0.005), lateral E:E' (r = 0.747; p = 0.033), and IVRT' (r = 0.831; p = 0.001). Peak -dP/dt also was correlated with IVRT' (r = 0.609; p = 0.036), and μ also was correlated with IVRT' (r = 0.884; p = 0.001). This study represents the first-ever comparison of diastolic echocardiographic and PVL indices in a single-ventricle population. The findings show that Doppler E:A, lateral E:E', and IVRT' correlate well with PVL measures of diastolic function. This study supports further validation of echocardiographic measures of diastolic function versus PVL measures of diastolic function in the single-ventricle population.

Heterogeneity of regional function and relation to ventricular morphology in patients with fontan circulation

The relation between underlying ventricular morphology and regional function in patients with Fontan circulation remains unclear. The aim of this study was to compare regional function and its heterogeneity in patients with tricuspid atresia (TA), biventricular apex-forming morphology (BiV), and controls. Nineteen patients (median age 12 years) with Fontan circulation who presented consecutively were prospectively enrolled and compared with age- and heart rate-matched controls. Most patients were in New York Heart Association class I (63%). Longitudinal systolic strain (S), systolic strain rate (SRsys), and early diastolic strain rate (SRdia) peaks were obtained from 6 ventricular segments, and a coefficient of variation by segment was calculated as a measure of regional heterogeneity. Systolic S, SRsys and SRdia peaks were decreased at the right and left lateral walls in both patient groups compared with controls (p ≤0.001 for all). Patients with TA had higher systolic S and SRsys in the middle of the right lateral wall than those with BiV morphology (p = 0.009 and p = 0.001, respectively). The mean coefficients of variation assessed by S and SRsys were similar in controls and patients with TA but lower in those with BiV than in controls and patients with TA (p <0.001 and p = 0.01, respectively). The mean coefficient of variation assessed by SRdia was greater only in patients with BiV than in controls (p = 0.001). In conclusion, patients with Fontan circulation have more heterogeneous systolic and early diastolic regional function than healthy control subjects, and patients with TA have better systolic regional function in the middle of the right lateral wall and less systolic heterogeneity than patients with BiV morphology.

Left ventricle after palliation of hypoplastic left heart syndrome: friend, fiend, or innocent bystander?

Hypoplasia of the left side of the heart is the most common cause of death from congenital heart disease in the first weeks of life. Once considered a surgically fatal disease, hypoplasia has been successfully palliated for more than 30 years. Although the palliative route is staged by an early differential bypass of the systemic outflow and the venous inflow to the right ventricle, the left ventricle remains anatomically and biologically influential throughout. Given the variation of the left ventricle, contemporary outcomes for different hypoplastic left heart subsets can vary both early after palliation and long term. This review critically examines the contemporary understanding of the structure and function of the hypoplastic ventricle in this syndrome. It also provides insight into future research directions relevant to clinicians and surgeons.

Myocardial deformation in the fetal single ventricle

BACKGROUND

In postnatal life, patients with single ventricle (SV) with morphologic right ventricles have a worse prognosis than those with morphologic left ventricles. The aim of this study was to test the hypotheses that (1) the SV in fetuses with SV has decreased longitudinal strain compared with fetuses with normal cardiac anatomy, and (2) fetuses with SV right ventricular (RV) morphology have decreased strain compared with those with SV left ventricular (LV) morphology.

METHODS

Fetal echocardiograms with SV RV and SV LV morphology were retrospectively compiled. Postprocessing analysis of the dominant ventricle was done using syngo Velocity Vector Imaging version 2.0. Peak global longitudinal strain (GLS) and global longitudinal strain rate (GL SR) were generated. Both the right and left ventricles were analyzed in fetuses with normal cardiac anatomy for comparison.

RESULTS

Fifty-four fetuses with SV (18 with LV morphology and 36 with RV morphology) were included in the study and compared with 54 controls matched for gestational age. Global longitudinal strain and GL SR were compared between fetuses with SV and normal fetuses and among SV subsets. When all four categories were compared (normal left ventricle, normal right ventricle, SV left ventricle, and SV right ventricle), there was no difference in GLS (P = .49) or in GL SR (P = .32) between any of the categories.

CONCLUSIONS

Comparable GLS and GL SR values between fetal SV of LV or RV morphology, as well as normal fetal left and right ventricles, reflect in utero preservation of systolic function of the SV heart.

Myocardial tagging by cardiovascular magnetic resonance: evolution of techniques--pulse sequences, analysis algorithms, and applications

Cardiovascular magnetic resonance (CMR) tagging has been established as an essential technique for measuring regional myocardial function. It allows quantification of local intramyocardial motion measures, e.g. strain and strain rate. The invention of CMR tagging came in the late eighties, where the technique allowed for the first time for visualizing transmural myocardial movement without having to implant physical markers. This new idea opened the door for a series of developments and improvements that continue up to the present time. Different tagging techniques are currently available that are more extensive, improved, and sophisticated than they were twenty years ago. Each of these techniques has different versions for improved resolution, signal-to-noise ratio (SNR), scan time, anatomical coverage, three-dimensional capability, and image quality. The tagging techniques covered in this article can be broadly divided into two main categories: 1) Basic techniques, which include magnetization saturation, spatial modulation of magnetization (SPAMM), delay alternating with nutations for tailored excitation (DANTE), and complementary SPAMM (CSPAMM); and 2) Advanced techniques, which include harmonic phase (HARP), displacement encoding with stimulated echoes (DENSE), and strain encoding (SENC). Although most of these techniques were developed by separate groups and evolved from different backgrounds, they are in fact closely related to each other, and they can be interpreted from more than one perspective. Some of these techniques even followed parallel paths of developments, as illustrated in the article. As each technique has its own advantages, some efforts have been made to combine different techniques together for improved image quality or composite information acquisition. In this review, different developments in pulse sequences and related image processing techniques are described along with the necessities that led to their invention, which makes this article easy to read and the covered techniques easy to follow. Major studies that applied CMR tagging for studying myocardial mechanics are also summarized. Finally, the current article includes a plethora of ideas and techniques with over 300 references that motivate the reader to think about the future of CMR tagging.

Two-dimensional speckle strain and dyssynchrony in single left ventricles vs. normal left ventricles

BACKGROUND

Patients with single left ventricle (LV) physiology maybe at increased risk for myocardial dysfunction and mechanical dyssynchrony. Newer echocardiographic modalities may be able to better quantitate LV function in this unique population. Our objective was to use 2D-speckle analysis of strain and strain rate to quantify systolic function and dyssynchrony in single LV post-Fontan patients and compare them to control LV patients.

METHODS

Patients with single LV status post-Fontan procedure and patients with normal biventricular anatomy were studied. Two-dimensional speckle echocardiography was used to measure strain, strain rate, time to peak, and longitudinal displacement in a six-segment model of the LV. Independent t-tests were used to compare group means.

RESULTS

Twelve patients with single LV physiology and thirteen control patients were studied. There was no significant difference in ages for the single LV patients vs. control patients (7.1 + 2.8 years vs. 5.7 + 1.8 years). Single LV strain values were significantly lower in four of the six segments compared with control LV (mid interventricular septal [IVS]: -19.3 + 6.4% vs. -23.8 + 3.5%, apical IVS: -20.8 + 5.4% vs. -27.4 + 4.7%, basal LV: -20.6 + 6.6% vs. -25.8 + 3.4%, and apical LV: -21.0 + 6.2% vs. -26.1 + 4.3%). Longitudinal displacement was lower for all three segments of the IVS for the single LV vs. control LV. Modified Yu index for strain and strain rate time to peak was longer in the single LV patients vs. controls (51.2 + 18.2 ms vs. 27.9 + 8.0 ms and 90.2 + 24.2 ms vs. 52.5 + 23.7 ms, respectively).

CONCLUSION

Significant differences in strain analysis between single LV patients vs. control patients with normal biventricular physiology exist at a relatively young age. Future studies are needed to determine the significance of these differences.

Temporal and spatial performance of vector velocity imaging in the human fetal heart

OBJECTIVES

To assess the spatial and temporal performance of fetal myocardial speckle tracking, using high-frame-rate (HFR) storing and Lagrangian strain analysis.

METHODS

Dummy electrocardiographic signaling permitted DICOM HFR in 124 normal fetuses and paired low-frame-rate (LFR) video storing at 25 Hz in 93 of them. Vector velocity imaging (VVI) tracking co-ordinates were used to compare time and spatial domain measures. We compared tracking success, Lagrangian strain, peak diastolic velocity and positive strain rate values in HFR vs. LFR video storing. Further comparisons within an HFR subset included Lagrangian vs. natural strain, VVI vs. M-mode annular displacement, and VVI vs. pulsed-wave tissue Doppler imaging (TDI) peak velocities.

RESULTS

HFR (average 79.4 Hz) tracking was more successful than LFR (86 vs. 76%, P = 0.024). Lagrangian and natural HFR strain correlated highly (left ventricle (LV): r = 0.883, P < 0.001; right ventricle (RV): r = 0.792, P < 0.001) but natural strain gave 20% lower values, suggesting reduced reliability of measurement. Lagrangian HFR strain was similar in LV and RV and decreased with gestation (P = 0.015 and P < 0.001, respectively). LV Lagrangian LFR strain was significantly lower than the values for the RV (P < 0.001) and those using paired LV-HFR recordings (P = 0.007). Annular displacement methods correlated highly (LV = 1.046, r = 0.90, P < 0.001; RV = 1.170, r = 0.88, P < 0.001). Early diastolic waves were visible in 95% of TDI, but in only 26% of HFR and 0% of LFR recordings, and HFR-VVI velocities were significantly lower than those for TDI (P < 0.001).

CONCLUSIONS

Doppler estimation of velocities remains superior to VVI but image gating and use of original co-ordinates should improve offline VVI assessment of fetal myocardial function.

Relation of size of secondary ventricles to exercise performance in children after fontan operation

The effects of the nondominant or secondary ventricle on the Fontan circulation are not known. The present study used cardiac magnetic resonance imaging to investigate the relations between secondary ventricular size and global cardiac performance. The Fontan cross-sectional study collected data from 7 centers participating in the Pediatric Heart Network. Subjects with complete cardiac magnetic resonance imaging data and an identifiable secondary ventricle were included in the analysis. Relationships between body surface area-adjusted parameters of the secondary ventricle (mass, end-diastolic volume, mass/volume ratio, and stroke volume) and the following measures were assessed. These measures included the percentage of predicted peak oxygen consumption and oxygen consumption at the ventilatory anaerobic threshold, ejection fraction of the main ventricular chamber, echocardiographic diastolic function grade, serum B-type natriuretic peptide, primary ventricular end-diastolic pressure, and parent-reported physical functioning summary score on the Child Health Questionnaire. Of the 546 enrolled subjects, 123 (age 12.1 ± 3.3 years, 56% male) had undergone cardiac magnetic resonance imaging, and 38 had achieved maximal aerobic capacity. A larger secondary ventricular end-diastolic volume, lower mass/volume ratio, and greater secondary/total ventricular stroke volume ratio were associated with a greater exercise capacity. No significant relationships were found between the measures of the secondary ventricle and the other outcomes. In conclusion, in children after the Fontan operation, a larger and less hypertrophied secondary ventricle with a greater contribution to stroke volume was associated with a better exercise capacity.

Accuracy and reproducibility of strain by speckle tracking in pediatric subjects with normal heart and single ventricular physiology: a two-dimensional speckle-tracking echocardiography and magnetic resonance imaging correlative study

BACKGROUND

Myocardial strain is a sensitive measure of ventricular systolic function. Two-dimensional speckle-tracking echocardiography (2DSE) is an angle-independent method for strain measurement but has not been validated in pediatric subjects. The aim of this study was to evaluate the accuracy and reproducibility of 2DSE-measured strain against reference tagged magnetic resonance imaging-measured strain in pediatric subjects with normal hearts and those with single ventricles (SVs) of left ventricular morphology after the Fontan procedure.

METHODS

Peak systolic circumferential strain and longitudinal strain (LS) in segments (n = 16) of left ventricles in age-matched and body surface area-matched 20 healthy and 12 pediatric subjects with tricuspid atresia after the Fontan procedure were measured by 2DSE and tagged magnetic resonance imaging. Average (global) and regional segmental strains measured by the two methods were compared using Spearman's and Bland-Altman analyses.

RESULTS

Global strains measured by 2DSE and tagged magnetic resonance imaging demonstrated close agreements, which were better for LS than circumferential strain and in normal left ventricles than in SVs (95% limits of agreement, +0.0% to +3.12%, -2.48% to +1.08%, -4.6% to +1.8%, and -3.6% to +1.8%, respectively). There was variability in agreement between regional strains, with wider limits in apical than in basal regions in normal left ventricles and heterogeneity in SVs. Strain values were significantly (P < .05) higher in normal left ventricles than in SVs except for basal LS, which were similar in both cohorts. The regional strains in normal left ventricles demonstrated an apicobasal magnitude gradient, whereas SVs showed heterogeneity. Reproducibility was the most robust for images obtained with frame rates between 60 and 90 frames/sec, global LS in both cohorts, and basal strains in normal left ventricles.

CONCLUSIONS

Strains measured by 2DSE agree with strain measured by magnetic resonance imaging globally but vary regionally, particularly in SVs. Global strain may be a more robust tool for cardiac functional evaluation than regional strain in SV physiology. The reliability of 2DSE-measured strain is affected by the frame rate, the nature of strain, and ventricular geometry.

Two-dimensional speckle strain and dyssynchrony in single right ventricles versus normal right ventricles

BACKGROUND

Patients with single-right ventricle (RV) physiology are at increased risk for myocardial dysfunction and mechanical dyssynchrony. Newer echocardiographic modalities may be better able to quantitate right ventricular function in this unique population. The aim of this study was to use two-dimensional speckle analysis of strain and strain rate to quantify systolic function and dyssynchrony in single-RV post-Fontan patients and compare them with values for controls.

METHODS

Patients with single RV who underwent Fontan palliation and patients with normal biventricular anatomy were studied. Two-dimensional speckle echocardiography was used to measure strain, strain rate, time to peak, and longitudinal displacement in a 6-segment model of the RV. Independent t tests were used to compare group means. P values < .05 were considered significant.

RESULTS

Thirteen patients were studied in each group. There was no significant difference in age between single-RV patients and controls (6.60 +/- 2.07 vs 5.75 +/- 1.83 years, respectively). Single-RV strain values were significantly lower in all 6 segments compared with values in controls (basal interventricular septum [IVS], -14.28 +/- 7.78% vs -22.00 +/- 2.36%; mid IVS, -17.70 +/- 4.54% vs -22.99 +/- 2.71%; apical IVS, -19.46 +/- 4.97% vs -25.42 +/- 4.06%; basal RV, -22.40 +/- 5.7% vs -41.42 +/- 5.42%; mid RV, -21.20 +/- 3.21% vs -39.67 +/- 6.04%; apical RV, -20.70 +/- 4.90% vs -33.68 +/- 3.90%). Systolic strain rate and longitudinal displacement were also lower in the free wall and apical IVS in single-RV patients compared with controls. The modified Yu index for strain time to peak was longer in the single-RV patients (43.16 +/- 13.63 vs 21.72 +/- 7.25 ms).

CONCLUSION

Significant differences in strain analysis between single-RV patients and patients with biventricular physiology exist at a relatively young age. Future studies are needed to determine the clinical significance of these differences.

Heterogeneous contraction of the left ventricle demonstrated by 2-dimensional strain imaging

BACKGROUND

Tissue Doppler imaging (TDI) is useful in quantifying regional myocardial function, but has a significant limitation of Doppler angle dependency. The recently developed 2-dimensional strain imaging (2DS), based on speckle tracking imaging (STI) technology, enables us to evaluate myocardial function independent of ultrasound beam direction. The aim of this study was to assess the mode of contraction of the left ventricle.

METHODS

Circumferential, radial and longitudinal strains were measured in 18 segments (anteroseptal, anterior, anterolateral, inferolateral, inferior and inferoseptal walls at the base, mid-ventricle and apex) from apical and short-axis views using 2DS in 24 healthy subjects (mean age, 33 ± 5 years). We divided the left ventricle into 2 sites: septum (anterior, anteroseptal and inferoseptal walls) and free walls (anterolateral, inferolateral and inferior walls). We then compared the mode of contraction between the septum and free walls.

RESULTS

At the base and mid-ventricular levels, circumferential strain was larger in the septum (-22.6 ± 3.6 vs. -18.3 ± 4.1% and -24.1 ± 4.8 vs. -18.4 ± 5.7%, respectively; p < 0.0001 each), and radial strain was larger in the free walls (33.4 ± 12.4 vs. 38.7 ± 14.5% and 37.8 ± 12.6 vs. 43.0 ± 11.6%, respectively; p < 0.001 each) at the basal and mid-ventricular levels, whereas both were relatively homogeneous at the apex. The longitudinal strain did not differ among walls.

CONCLUSIONS

Heterogeneous contraction is seen in the left ventricle. The septum mainly contracts circumferentially, whereas the free walls contract radially. 2DS is helpful in understanding the mode of 3-dimensional myocardial contraction.

Study of ventricular interaction during pulmonary embolism using clinical identification in a minimum cardiovascular system model

Cardiovascular disturbances are difficult to diagnose and treat because of the large range of possible underlying dysfunctions combined with regulatory reflex mechanisms that can result in conflicting clinical data. Thus, medical professionals often rely on experience and intuition to optimize hemodynamics in the critically ill. This paper combines an existing minimal cardiovascular system model with an extended integral based parameter identification method to track the evolution of induced pulmonary embolism in porcine data. The model accounts for ventricular interaction dynamics and is shown to predict an increase in the right ventricle expansion index and a decrease in septum volume consistent with known physiological response to pulmonary embolism. The full range of hemodynamic responses was captured with mean prediction errors of 4.1% in the pressures and 3.1% in the volumes for 6 sets of clinical data. Pulmonary resistance increased significantly with the onset of embolism in all cases, as expected, with the percentage increase ranging from 89.98% to 261.44% of the initial state. These results are an important first step towards model-based cardiac diagnosis in the Intensive Care Unit.

The effect of left ventricular size on right ventricular hemodynamics in pediatric survivors with hypoplastic left heart syndrome

BACKGROUND

Outcome status in patients with hypoplastic left heart syndrome (HLHS) is partially dependent on right ventricular (RV) systolic function. In other disease states, ventricular function is impacted by anatomy and physiology of the contralateral ventricle. In HLHS, it is suggested that a relatively larger left ventricular (LV) size may negatively impact RV function because it becomes a "passenger" without providing any systolic or diastolic physiologic benefit. The purpose of this study was to determine whether LV size adversely affects RV systolic function in surviving patients with HLHS.

METHODS

The hospital database was searched for all patients with HLHS and technically adequate echocardiograms born in the last 6 years and who had survived at least the Norwood procedure. LV size was assessed by echocardiographic measurement of LV end-diastolic short-axis and apical area. RV function was assessed by short-axis and apical fractional area change as well as the myocardial performance index (Tei). Measurements were made at up to 4 time points depending on duration of follow-up (1 - pre-Norwood; 2 - pre-Glenn; 3 - pre-Fontan; and 4- post-Fontan).

RESULTS

A total of 48 patients were studied. LV size showed sufficient variability in the patient population (1.0-21 cm(2)/body surface area, pre-Norwood). RV function tended to worsen across the time periods but these changes did not reach statistical significance. Regression analysis showed no effect of LV size on RV function before Norwood operation. Significant correlations existed between LV size indices and RV functional indices before Glenn shunt but these were inconsistent in the direction of their effect. Only before Fontan operation did the correlation between LV size and RV function become both consistent and statistically significant; specifically larger LV size correlated significantly with poor RV systolic function (short-axis RV fractional area change vs LV area r = -0.4, P = .03 and RV Tei vs LV area r = 0.5, P = .02). These relationships were not apparent after Fontan operation.

CONCLUSION

In surviving patients with HLHS, larger LV size does not seem to negatively impact RV function before or after Norwood procedure nor does it seem to have an adverse effect on RV function chronically (after Fontan). However, further study with larger population size will be necessary to see whether these findings remain negative and are true for nonsurvivors as well.

Model-based cardiac diagnosis of pulmonary embolism

A minimal cardiac model has been shown to accurately capture a wide range of cardiovascular system dynamics commonly seen in the intensive care unit (ICU). However, standard parameter identification methods for this model are highly non-linear and non-convex, hindering real-time clinical application. An integral-based identification method that transforms the problem into a linear, convex problem, has been previously developed, but was only applied on continuous simulated data with random noise. This paper extends the method to handle discrete sets of clinical data, unmodelled dynamics, a significantly reduced data set theta requires only the minimum and maximum values of the pressure in the aorta, pulmonary artery and the volumes in the ventricles. The importance of integrals in the formulation for noise reduction is illustrated by demonstrating instability in the identification using simple derivative-based approaches. The cardiovascular system (CVS) model and parameter identification method are then clinically validated on porcine data for pulmonary embolism. Errors for the identified model are within 10% when re-simulated and compared to clinical data. All identified parameter trends match clinically expected changes. This work represents the first clinical validation of these models, methods and approach to cardiovascular diagnosis in critical care.

Report of the National Heart, Lung, and Blood Institute Working Group on Research in Adult Congenital Heart Disease

The Working Group on research in adult congenital heart disease (ACHD) was convened in September 2004 under the sponsorship of National Heart, Lung, and Blood Institute (NHLBI) and the Office of Rare Diseases, National Institutes of Health, Department of Health and Human Services, to make recommendations on research needs. The purpose of the Working Group was to advise the NHLBI on the current state of the science in ACHD and barriers to optimal clinical care, and to make specific recommendations for overcoming those barriers. The members of the Working Group were chosen to provide expert input on a broad range of research issues from both scientific and lay perspectives. The Working Group reviewed data on the epidemiology of ACHD, long-term outcomes of complex cardiovascular malformations, issues in assessing morphology and function with current imaging techniques, surgical and catheter-based interventions, management of related conditions including pregnancy and arrhythmias, quality of life, and informatics. After research and training barriers were discussed, the Working Group recommended outreach and educational programs for adults with congenital heart disease, a network of specialized adult congenital heart disease regional centers, technology development to support advances in imaging and modeling of abnormal structure and function, and a consensus on appropriate training for physicians to provide care for adults with congenital heart disease.

Simulating transient ventricular interaction using a minimal cardiovascular system model

A minimal closed-loop cardiovascular system (CVS) model has been developed that can simulate ventricular interaction due to both direct interaction through the septum and series interaction through the circulation system. The model is used to simulate canine experiments carried out to study the transient response of the left ventricle due to changes in right ventricle pressures and volumes. The model-simulated trends in left and right ventricle pressures and volumes, septum deflection and arterial flow rates are compared with the experimental results. In spite of the limited physiological data available describing the animals, the model is shown to capture all the transient trends in the experimental data. This is the first known example of a physiological model that can capture all these trends. The model is then used to illustrate the separate effects of direct and series interactions independently. This study proves the value of this modelling method to be used in conjunction with experimental data for delineating and understanding the factors that contribute to ventricular dynamics.

Tagged magnetic resonance imaging of the heart: a survey

Magnetic resonance imaging (MRI) of the heart with magnetization tagging provides a potentially useful new way to assess cardiac mechanical function, through revealing the local motion of otherwise indistinguishable portions of the heart wall. While still an evolving area, tagged cardiac MRI is already able to provide novel quantitative information on cardiac function. Exploiting this potential requires developing tailored methods for both imaging and image analysis. In this paper, we review some of the progress that has been made in developing such methods for tagged cardiac MRI, as well as some of the ways these methods have been applied to the study of cardiac function.

Analysis of cardiac ventricular wall motion based on a three-dimensional electromechanical biventricular model

This paper describes a biventricular model, which couples the electrical and mechanical properties of the heart, and computer simulations of ventricular wall motion and deformation by means of a biventricular model. In the constructed electromechanical model, the mechanical analysis was based on composite material theory and the finite-element method; the propagation of electrical excitation was simulated using an electrical heart model, and the resulting active forces were used to calculate ventricular wall motion. Regional deformation and Lagrangian strain tensors were calculated during the systole phase. Displacements, minimum principal strains and torsion angle were used to describe the motion of the two ventricles. The simulations showed that during the period of systole, (1) the right ventricular free wall moves towards the septum, and at the same time, the base and middle of the free wall move towards the apex, which reduces the volume of the right ventricle; the minimum principle strain (E3) is largest at the apex, then at the middle of the free wall and its direction is in the approximate direction of the epicardial muscle fibres; (2) the base and middle of the left ventricular free wall move towards the apex and the apex remains almost static; the torsion angle is largest at the apex; the minimum principle strain E3 is largest at the apex and its direction on the surface of the middle wall of the left ventricle is roughly in the fibre orientation. These results are in good accordance with results obtained from MR tagging images reported in the literature. This study suggests that such an electromechanical biventricular model has the potential to be used to assess the mechanical function of the two ventricles, and also could improve the accuracy of ECG simulation when it is used in heart-torso model-based body surface potential simulation studies.

Is routine cardiac catheterization necessary in the management of patients with single ventricles across staged Fontan reconstruction? No!

With the advent of cardiac magnetic resonance imaging and high-resolution echocardiography, cardiac catheterization is unnecessary in clinical protocols in the "routine" single ventricle patient. Catheterization adds little to clinical care in these cases, and there are significant risks and costs associated with it. Catheterization should be reserved for cases in which noninvasive evaluations are equivocal, conflictory, demonstrate deterioration, or needed for intervention. This article delineates the role of noninvasive evaluations relative to cardiac catheterization in the routine single ventricle patient.

Left ventricular performance of pulmonary atresia with intact ventricular septum after right heart bypass surgery

OBJECTIVE

The left ventricular performance in patients with pulmonary atresia with intact ventricular septum who were Fontan candidates before and after the bidirectional Glenn procedure and a staged total cavopulmonary connection was compared with that in patients with tricuspid atresia.

METHODS

Contractility (end-systolic elastance), afterload (effective arterial elastance), and ventricular efficiency (ventriculoarterial coupling, arterial elastance/end-systolic elastance ratio), and the ratio of stroke work and pressure-volume area were approximated on the basis of cardiac catheterization data before the bidirectional Glenn procedure, before and after staged total cavopulmonary connection, and approximately 1 year after the completion of total cavopulmonary connection in 20 patients with pulmonary atresia with intact ventricular septum and 21 patients with tricuspid atresia.

RESULTS

The end-systolic elastance of the pulmonary atresia with intact ventricular septum group was significantly inferior to that of the tricuspid atresia group after bidirectional Glenn procedure and total cavopulmonary connection (1 year after total cavopulmonary connection 1.85 +/- 0.51 mm Hg . m 2 . mL -1 vs 2.84 +/- 0.96 mm Hg . m 2 . mL -1 , P < .01). The arterial elastance was not different between groups throughout the assessment period and tended to increase in a stepwise fashion after bidirectional Glenn procedure and total cavopulmonary connection. The arterial elastance/end-systolic elastance ratio and ratio of stroke work and pressure-volume area of the pulmonary atresia with intact ventricular septum group tended to worsen, whereas those of the tricuspid atresia group tended to improve. The difference reached statistical significance 1 year after total cavopulmonary connection (1.15 +/- 0.35 vs 0.82 +/- 0.23 and 64.2% +/- 6.7% vs 71.3% +/- 5.7%, respectively, P < .05 and P < .05, respectively).

CONCLUSION

The contractility and ventricular efficiency of patients with pulmonary atresia with intact ventricular septum are inferior to those of patients with tricuspid atresia after bidirectional Glenn procedure and total cavopulmonary connection. A high-pressure residual right ventricle may impair the left ventricular performance of patients with pulmonary atresia with intact ventricular septum after bidirectional Glenn procedure and total cavopulmonary connection.