A novel, data-driven conceptualization for critical left heart obstruction.

BACKGROUND: Qualitative features of aortic and mitral valvar pathology have traditionally been used to classify congenital cardiac anomalies for which the left heart structures are unable to sustain adequate systemic cardiac output. We aimed to determine if novel groups of patients with greater clinical relevance could be defined within this population of patients with critical left heart obstruction (CLHO) using a data-driven approach based on both qualitative and quantitative echocardiographic measures. METHODS: An independent standardized review of recordings from pre-intervention transthoracic echocardiograms for 651 neonates with CLHO was performed. An unsupervised cluster analysis, incorporating 136 echocardiographic measures, was used to group patients with similar characteristics. Key measures differentiating the groups were then identified. RESULTS: Based on all measures, cluster analysis linked the 651 neonates into groups of 215 (Group 1), 338 (Group 2), and 98 (Group 3) patients. Aortic valve atresia and left ventricular (LV) end diastolic volume were identified as significant variables differentiating the groups. The median LV end diastolic area was 1.35, 0.69, and 2.47 cm2 in Groups 1, 2, and 3, respectively (p < 0.0001). Aortic atresia was present in 11% (24/215), 87% (294/338), and 8% (8/98), in Groups 1, 2, and 3, respectively (p < 0.0001). Balloon aortic valvotomy was the first intervention for 9% (19/215), 2% (6/338), and 61% (60/98), respectively (p < 0.0001). For those with an initial operation, single ventricle palliation was performed in 90% (176/215), 98% (326/338), and 58% (22/38) (p < 0.0001). Overall mortality in each group was 27% (59/215), 41% (138/338), and 12% (12/98) (p < 0.0001). CONCLUSIONS: Using a data-driven approach, we conceptualized three distinct patient groups, primarily based quantitatively on baseline LV size and qualitatively by the presence of aortic valve atresia. Management strategy and overall mortality differed significantly by group. These groups roughly correspond anatomically and are analogous to multi-level LV hypoplasia, hypoplastic left heart syndrome, and critical aortic stenosis, respectively. Our analysis suggests that quantitative and qualitative assessment of left heart structures, particularly LV size and type of aortic valve pathology, may yield conceptually more internally consistent groups than a simplistic scheme limited to valvar pathology alone.

Left ventricular hypoplasia: a spectrum of disease involving the left ventricular outflow tract, aortic valve, and aorta.

"Hypoplastic left heart syndrome" is an unsatisfactory term describing lethal underdevelopment of the left ventricle (LV). It represents the more severe end of a spectrum of LV hypoplasia, mandating single-ventricle palliation or cardiac transplantation. Less severe "borderline" ventricular hypoplasia may instead allow various biventricular therapeutic strategies and better long-term outcomes. In this review, we consider factors causing and modifying the abnormal development of the LV. LV hypoplasia is typically seen in association with left ventricular outflow tract obstruction, itself part of a spectrum of related defects with common etiologies. Secondary responses to outflow obstruction are complex but involve abnormal flow dynamics and shear stresses that result in compromised and poorly orchestrated ventricular growth and development. Subsequent remodeling is likely influenced by genetic modifiers, including intrinsic myocardial growth signaling pathways, possibly including those of HAND transcription factors. In addition, during the latter stages of gestation, cardiomyocytes undergo a switch in myogenic potential and lose the ability to undergo mitosis. Ventricular hyperplasia can therefore no longer occur; remodeling is instead limited to muscular hypertrophy. Subtle differences in this switch in myogenic potential--and modulators thereof--are likely to be of clinical and therapeutic importance, especially in children with "borderline LVs" being considered for fetal interventions or post-natal biventricular repair strategies. Finally, by more clearly understanding the initiators and propagators of abnormal ventricular development, we can hope to lean away from grouping a heterogeneous group of infants together under the unsatisfactory term "hypoplastic left heart syndrome."

Comparison of right ventricular deformation and dyssynchrony in patients with different subtypes of hypoplastic left heart syndrome after Fontan surgery using two-dimensional speckle tracking.

BACKGROUND: The left ventricle in patients with hypoplastic left heart syndrome may influence right ventricular function and outcome. We aimed to investigate differences in right ventricular deformation and intraventricular dyssynchrony between hypoplastic left heart syndrome patients with different anatomical subtypes and left ventricle sizes after Fontan surgery using two-dimensional speckle tracking. PATIENTS AND METHODS: We examined 29 hypoplastic left heart syndrome patients aged 5.4 plus or minus 2.8 years after Fontan surgery and compared 15 patients with mitral and aortic atresia with the remaining 14 patients with other anatomic subtypes. We used two-dimensional speckle tracking to measure the global and regional systolic longitudinal strain and strain rate as well as intraventricular dyssynchrony. RESULTS: Global strain (-19.5, 2.8% versus -17.4, 3.9%) and global strain rate (-1.0, 0.2 per second versus -0.9, 0.3 per second) were not different between groups. The mitral and aortic atresia group had higher strain in the basal septal (-13.0, 5.0% versus -3.9, 9.3%, p = 0.003) and mid-septal (-19.4, 4.7% versus -13.2, 6.5%, p = 0.009) segments, and higher strain rates in the mid-septal segment (-1.14, 0.3 per second versus -0.95, 0.4 per second, p = 0.047), smaller left ventricle area (0.18, 0.41 square centimetre versus 2.83, 2.07 square centimetre, p = 0.0001), and shorter wall-to-wall delay (38, 29 milliseconds versus 81, 57 milliseconds, p = 0.02). CONCLUSION: Significant differences in regional deformation and intraventricular dyssynchrony exist between the mitral and aortic atresia subtype with small left ventricles and the other anatomic subtypes with larger left ventricles after Fontan surgery.

The systolic to diastolic duration ratio in children with hypoplastic left heart syndrome: a novel Doppler index of right ventricular function.

BACKGROUND: Right ventricular (RV) function is an important determinant of clinical status in children with hypoplastic left heart syndrome (HLHS). However, assessment of RV function remains challenging because of its complex morphology. We investigated the S/D duration ratio in children with HLHS as a novel index of global RV function. METHODS: We measured systolic (S) and diastolic (D) duration using tricuspid regurgitation duration from Doppler flow, to calculate the S/D ratio in 33 children with HLHS and 33 control subjects matched for age and sex. We compared the S/D ratio between patients with HLHS and control subjects, between patients with HLHS and normal and abnormal RV function, and between patients with HLHS at different stages of palliation. We further correlated the S/D ratio with catheterization data. RESULTS: Patients and control subjects were well matched for age (3.12 +/- 4.5 vs 3 +/- 4.5 years, not significant) sex, and heart rate (cycle length 524 +/- 179 vs 575 +/- 162 milliseconds, not significant). Patients with HLHS had a significantly higher S/D ratio than control subjects (1.65 +/- 0.85 vs 0.85 +/- 0.2, P < .0001). The S/D ratio became increasingly elevated in HLHS at higher heart rates, but not in control subjects. The S/D ratio was significantly higher in patients with HLHS and decreased RV function as compared with patients with HLHS and normal RV function (2.2 +/- 0.7 vs 1.5 +/- 0.47, P = .006), and significantly increased in patients with Norwood stage 1 versus patients with Norwood stages 2 and 3 HLHS (2.16 vs 1.4 and 1.32, respectively, P < .01 and P < .001, respectively). The S/D ratio did not correlate with catheterization-derived RV end-D pressure or cardiac index. CONCLUSIONS: Patients with HLHS have an increased S/D ratio as a result of a shortened D and prolonged S. Measurement of the S/D duration ratio using Doppler flow is a novel method to augment assessment of global RV function in HLHS.

The nomenclature, definition and classification of hypoplastic left heart syndrome.

The hypoplastic left heart syndrome encompasses a spectrum of cardiac malformations that are characterized by significant underdevelopment of the components of the left heart and the aorta, including the left ventricular cavity and mass. At the severe end of the spectrum is found the combination of aortic and mitral atresia, when the left ventricle can be close to non-existent. At the mild end are the patients with hypoplasia of the aortic and mitral valves, but without intrinsic valvar stenosis or atresia, and milder degrees of left ventricular hypoplasia. Although the majority of the patients are suitable only for functionally univentricular repair, a small minority may be candidates for biventricular repair. The nature of the syndrome was a topic for discussion at the second meeting of the International Working Group for Mapping and Coding of Nomenclatures for Paediatric and Congenital Heart Disease, the Nomenclature Working Group, held in Montreal, Canada, over the period January 17 through 19, 2003. Subsequent to these discussions, the Nomenclature Working Group was able to create a bidirectional crossmap between the nomenclature initially produced jointly on behalf of the European Association for Cardio-Thoracic Surgery and the Society of Thoracic Surgeons, and the alternative nomenclature developed on behalf of the Association for European Paediatric Cardiology. This process is a part of the overall efforts of the Nomenclature Working Group to create a comprehensive and all-inclusive international system of nomenclature for paediatric and congenital cardiac disease, the International Paediatric and Congenital Cardiac Code. In this review, we discuss the evolution of nomenclature and surgical treatment for the spectrum of lesions making up the hypoplastic left heart syndrome and its related malformations. We also present the crossmap of the associated terms for diagnoses and procedures, as recently completed by the Nomenclature Working Group.

Biventricular repair in neonates with hypoplastic left heart complex.

BACKGROUND: Multiple obstructions in the left heart-aorta complex have been associated with poor survival. No consensus exists as to whether these patients will have a favorable outcome with biventricular repair where most advocate a univentricular approach. METHODS: Since late 1988, all 11 neonates seen with hypoplastic left heart complex, which includes aortic arch obstruction, underwent biventricular repair. All patients had antegrade aortic flow and no intrinsic aortic or mitral stenosis. Elimination of the extracardiac afterload was achieved by extensive ascending aorta and aortic arch reconstruction with a pulmonary homograft patch. All intracardiac shunts were eliminated to fully preload the left heart. The median age at first operation was 7 days and the mean weight, 3.59+/-0.49 kg. The echocardiographic variables used to evaluate the left heart-aorta complex were reviewed, and the preoperative and postoperative measurements were compared. RESULTS: There were two early deaths. Four patients had six reoperations for left ventricular outflow tract obstruction, 2 of whom have required prosthetic valve replacement (1, aortic and mitral; 1, aortic), and 2 patients had three reoperations for recurrent coarctation. There was one late death at 3 years from pulmonary hypertension. Mean follow-up was 44+/-35 months. The 8 current survivors are all in New York Heart Association class I or II. The actuarial survival rate at 8 years is 63%, and the freedom from reoperation at 3 years is 25%. CONCLUSIONS: We have successfully achieved biventricular repair in most of the patients with hypoplastic left heart complex, a subset of patients with hypoplastic left heart syndrome. Some growth of the left ventricular structures was already observed at the time of hospital discharge. However, reoperation, particularly for left ventricular outflow tract obstruction, appears likely. Increasing experience will more accurately define predictive criteria for the feasibility of biventricular repair.

Síndrome de corazón izquierdo hipoplásico: producción experimetal, anatomía quirúrgica y clasificación

Este trabajo monográico se inicío hace 7 años con la producción experimental del Síndrome de Corazón Izquierdo Hipoplásico, realizada en el Laboratorio de Embriología Cardiovascular del Centro Especial Ramón y Cajal de Madrid España, siendo Jefe de Laboratorio la Dra. María Victoria de la Cruz. El estudio morfológico fue elaborado con material de los Museos de piezas anatómicas del Instituto Materno Infantil de la Misericordia de Bogotá (31 corazones) y del Hospital Ciudad Sanitaria Virgen del Rosario de Sevilla España (17 corazones). Por ser colecciones de piezas anatómicas, no fue posible conocer datos de los pacientes, pero se deduce por el tamaño de los corazones, que pertenecían a recien nacidos