Spectrum of hearts with one underdeveloped and one dominant ventricle

The concept of double inlet-double outlet right ventricle: a distinct congenital heart disease

The aim of this study was to estimate the incidence and to analyze the anatomy of double inlet-double outlet right ventricle complex and its associated cardiac anomalies in our autopsy series. Among the 1640 hearts with congenital heart disease of our Anatomical Collection, we reviewed the specimens with double inlet-double outlet right ventricle, according to the sequential-segmental analysis, identifying associated cardiac anomalies and examining lung histology to assess the presence of pulmonary vascular disease. We identified 14 hearts with double inlet-double outlet right ventricle (0.85%). Right atrial isomerism was observed in 10 hearts, situs solitus in 3 and left atrial isomerism in one. Regarding the mode of atrioventricular connection, all hearts but one had a common atrioventricular valve. Systemic or pulmonary venous abnormalities were noted in all patients with atrial isomerism. In nine patients a valvular or subvalvular pulmonary stenosis was present. Among the functionally "univentricular hearts", double inlet- double outlet right ventricle represents a peculiar entity, mostly in association with right atrial isomerism. Multiple cardiac anomalies are associated and may complicate surgical repair.

Comparability of Z-score equations of cardiac structures in hypoplastic left heart complex

BACKGROUND

Hypoplastic left heart complex (HLHC) is characterized by a mitral valve or an aortic valve annular Z score < -2, antegrade flow in the ascending aorta, ductal dependency, coarctation or aortic arch hypoplasia, and absence of significant (sub)valvar stenosis. The Z scores of the mitral and aortic valve annuli are major determinants of HLHC. Therefore, the algorithm for Z-score calculation is essential for diagnosis. However, no single universal method of calculation is in use. In the scientific literature addressing HLHC, various Z-score calculation methods have been applied. The aim of this study was to evaluate Z scores derived from two-dimensional echocardiographic dimensions in patients with HLHC.

METHODS

To compare the different published methods using two-dimensional echocardiographic measures for Z-score calculation, a cohort of 18 newborns diagnosed with HLHC was retrospectively evaluated. In addition, the methods to determine body surface area in newborns were evaluated.

RESULTS

Three Z-score calculation methods were included and compared. Using the method of Daubeney et al. to calculate Z scores in our cohort illustrated a lack of correlation beyond a Z score < 0, compared with the methods of Zilberman et al. and Pettersen et al. Z scores calculated using Zilberman et al.'s and Pettersen et al.'s methods were fairly consistent. The equations used by Pettersen et al. are based on the largest population of neonates.

CONCLUSION

Although the different methods for calculating Z scores for mitral and aortic valve dimensions correspond fairly well in the normal range, Z scores < -2 diverge substantially. A useful scientific comparison of published data and outcomes of patients with HLHC remains elusive. The Z-score calculation algorithms used by Pettersen et al. appear to be the most appropriate for use in an evaluation of HLHC. Because these different methods can yield different values, reporting the method as well as the Z score is essential for an accurate diagnosis. Similarly, the method used to determine body surface area should be reported.

Echocardiographic definition and surgical decision-making in unbalanced atrioventricular septal defect: a Congenital Heart Surgeons' Society multiinstitutional study

BACKGROUND

Although identification of unbalanced atrioventricular septal defect (AVSD) is obvious when extreme, exact criteria to define the limits of unbalanced are not available. We sought to validate an atrioventricular valve index (AVVI) (left atrioventricular valve area/total atrioventricular valve area, centimeters squared) as a discriminator of balanced and unbalanced forms of complete AVSD and to characterize the association of AVVI with surgical strategies and outcomes.

METHODS AND RESULTS

Diagnostic echocardiograms and hospital records of 356 infants with complete AVSD at 4 Congenital Heart Surgeons' Society (CHSS) institutions (2000-2006) were reviewed and AVVI measured (n=315). Patients were classified as unbalanced if AVVI≤0.4 (right dominant) or ≥0.6 (left dominant). Surgical strategy and outcomes were examined across the range of AVVI. Competing risks analysis until the time of commitment to a surgical strategy examined 4 end states: biventricular repair (BVR), univentricular repair (UVR), pulmonary artery banding (PAB), and death before surgery. A prediction nomogram for surgical strategy based on AVVI was developed. The majority of patients had balanced AVSD (0.4<AVVI<0.6) and underwent BVR. Patients with AVVI<0.19 uniformly underwent UVR. Heterogeneous repair strategies were found when 0.19≤AVVI≤0.39 (UVR and BVR), with a disproportionate number of deaths in this range. AVVI≥0.6 (left dominant) was less common. The proportion of subjects predicted for the end states at 12 months after diagnosis are: BVR, 86%; UVR, 7%; PAB, 1%; death without surgery, 1%; alive without surgery, 5%.

CONCLUSIONS

AVVI effectively characterizes the transition between balanced and unbalanced AVSD with important correlation to anatomic substrate and selected surgical strategy.

Designing therapeutic strategies for patients with a dominant left ventricle, discordant ventriculo-arterial connections, and unobstructed flow of blood to the lungs

The palliation of the cyanotic child with a dominant morphologically left ventricle, discordant ventriculo-arterial connections, and obstruction to the pulmonary outflow tract has continued to evolve and mature. The evolution began in the early days of surgical palliation with the Blalock-Taussig shunt, extended to construction of cavopulmonary shunts, if required, and then to the Fontan procedure and its subsequent modifications. This journey took nearly 30 years to complete. There is increasing clinical data to document the beneficial effects of this approach, with ever-improving outcomes. Some aspects of the history of the cavopulmonary shunt have been previously reviewed in this journal and elsewhere, as have analysis of outcomes for some groups of patients considered for surgical completion of the Fontan circulation. While there has been some ongoing interest in ventricular septation since the early success of Sakakibara et al., this approach has largely been abandoned. Considerably more challenges and debate resonate in the surgical algorithms defined for patients whose hearts are characterized by a dominant left ventricle, discordant ventriculo-arterial connections, and unobstructed flow of blood to the lungs. This latter group will be the focus of this review, as will the aetiology of the myocardial hypertrophy that is particularly frequent in this group of patients, its clinical recognition, indeed its anticipation, and the multiple surgical strategies designed to prevent or treat it. All these manoeuvres are considered to optimise suitability for, and outcome from, creation of the Fontan circulation.

Morphometric analysis of unbalanced common atrioventricular canal using two-dimensional echocardiography

OBJECTIVES

This study was designed to define morphometric echocardiographic variables of unbalanced common atrioventricular canal (CAVC) that could aid in appropriate referral for surgical repair.

BACKGROUND

Unbalanced CAVC has a high surgical mortality rate. This may be secondary to inappropriate referral of some patients for two-ventricle repair (closure of septal defects) instead of single-ventricle repair (Norwood palliation and Fontan operation).

METHODS

The echocardiograms of 103 patients with CAVC were retrospectively reviewed. In the subcostal left anterior oblique view, the area of the atrioventricular (AV) valve aportioned over each ventricle was measured, and an AV valve index (AVVI) was calculated as left/right valve area. The ventricular cavity ratio between the two ventricles was estimated as left ventricular length times width divided by right ventricular length times width. These variables were correlated with surgical referral and outcome.

RESULTS

Patients previously categorized as having balanced CAVC all had AVVI > 0.67 (n = 77). Of the patients with unbalanced CAVC (n = 26), 11 had ductal-dependent circulation and underwent Norwood palliation (AVVI 0.21 +/- 0.13, mean +/- SD), and 15 had two-ventricle repair (AVVI 0.51 +/- 0.12, p < 0.0001). Of these 15 patients, 9 have survived, with no difference in mean AVVI between survivors and nonsurvivors (0.52 +/- 0.11 versus 0.49 +/- 0.13, p = 0.72). For all 103 patients, AVVI correlated with ventricular cavity ratio. However, of the unbalanced CAVC group who underwent two-ventricle repair, three nonsurvivors had a discrepancy between AVVI and ventricular cavity ratio (low AVVI but normal ventricular size). A large ventricular septal defect was present in all six nonsurvivors but in only four of nine survivors (p < 0.05).

CONCLUSIONS

Echocardiographic morphometry is useful in defining unbalance in CAVC. If AVVI is < 0.67 in the presence of a large ventricular septal defect, a single-ventricle approach to repair should be considered.