Hypoplastic Ventricle Research Articles

Case-based approach to demonstrate utility of cardiac magnetic resonance imaging (MRI) for planning biventricular repair with inconclusive echo: illustration of two cases.

Congenital heart defects that present earlier in life and involving a hypoplastic ventricle are sometimes channeled towards single-ventricle repair because of anatomical or logistic challenges (1). With the single-ventricular repair, the final result is the shunting of venous return directly into the pulmonary artery and the utilization of the functioning ventricle for systemic circulation (2). Though singleventricular repair has remarkable short-term results, long-term survivors experience declines in exercise tolerance, heart failure, arrhythmias, and thromboembolic complications (3). Given long-term functional and survival advantages of a two-ventricle circulation, exploring feasibility of biventricular repair is essential for improving prognosis. However, a successful biventricular repair requires sufficiently functioning ventricles to sustain a balanced flow through the pulmonary and systemic circuit. To evaluate the functional adequacy of the ventricle with hypoplasia, echocardiogram is conventionally used.

Congenitally corrected transposition: complex anatomic repair or Fontan pathway?

Background Successful anatomic repair of congenitally corrected transposition of the great arteries achieves excellent outcomes. Several centers report excellent long-term survival with the Fontan pathway as well. We have selectively applied both approaches depending on individual patient morphology, with anatomic repair preferred but utilizing the Fontan pathway when high technical complexity or operative risk is anticipated. Methods Hospital records over an 18-year period (1998-2016) were reviewed to identify patients with congenitally corrected transposition of the great arteries who underwent surgical management. Physiological repairs and hypoplastic ventricles were excluded. Patient- and procedure-related variables were reviewed. Results We identified 19 patients. Group 1 consisted of 12 anatomic repairs, of which 10 (83.3%) required prior interim staging procedures. Mean age at anatomic repair was 2.6 ± 1.3 years, mean follow-up was 8.7 ± 5.3 years. Nine (75%) patients experienced important complications and 4 (33.3%) required reintervention during follow-up. There were no deaths; one patient required heart transplantation. Group 2 (7 patients) underwent Fontan palliation. Mean age at Fontan completion was 7.2 ± 3.8 years, mean follow-up was 6.3 ± 4 years. There was no reintervention, death, or transplant. Conclusion Patients with congenitally corrected transposition of the great arteries and two adequate-sized ventricles do well with both anatomic repair and the Fontan pathway in the medium term. Excellent outcomes with reduced early complication and reintervention rates can be achieved for this cohort of patients when a strategy of avoiding complex anatomic repair in favor of the Fontan pathway is used.

Morphological three-dimensional analysis of papillary muscles in borderline left ventricles.

Mitral valve anatomy has a significant impact on potential surgical options for patients with hypoplastic or borderline left ventricle. Papillary muscle morphology is a major component regarding this aspect. The purpose of this study was to use cardiac magnetic resonance to describe the differences in papillary muscle anatomy between normal, borderline, and hypoplastic left ventricles. We carried out a retrospective, observational cardiac magnetic resonance study of children (median age 5.36 years) with normal (n=30), borderline (n=22), or hypoplastic (n=13) left ventricles. Borderline and hypoplastic cases had undergone an initial hybrid procedure. Morphological features of the papillary muscles, location, and arrangement were analysed and compared across groups. All normal ventricles had two papillary muscles with narrow pedicles; however, 18% of borderline and 46% of hypoplastic cases had a single papillary muscle, usually the inferomedial type. In addition, in borderline or hypoplastic ventricles, the supporting pedicle occasionally displayed a wide insertion along the ventricular wall. The length ratio of the superolateral support was significantly different between groups (normal: 0.46±0.08; borderline: 0.39±0.07; hypoplastic: 0.36±0.1; p=0.009). No significant difference, however, was found when analysing the inferomedial type (0.42±0.09; 0.38±0.07; 0.39±0.22, p=0.39). The angle subtended between supports was also similar among groups (113°±17°; 111°±51° and 114°±57°; p=0.99). A total of eight children with borderline left ventricle underwent biventricular repair. There were no significant differentiating features for papillary muscle morphology in this subgroup. The superolateral support can be shorter or absent in borderline or hypoplastic left ventricle cases. The papillary muscle pedicles in these patients often show a broad insertion. These changes have important implications on surgical options and should be described routinely.

Increased regurgitant flow causes endocardial cushion defects in an avian embryonic model of congenital heart disease.

The relationship between changes in endocardial cushion and resultant congenital heart diseases (CHD) has yet to be established. It has been shown that increased regurgitant flow early in embryonic heart development leads to endocardial cushion defects, but it remains unclear how abnormal endocardial cushions during the looping stages might affect the fully septated heart. The goal of this study was to reproducibly alter blood flow in vivo and then quantify the resultant effects on morphology of endocardial cushions in the looping heart and on CHDs in the septated heart. Optical pacing was applied to create regurgitant flow in embryonic hearts, and optical coherence tomography (OCT) was utilized to quantify regurgitation and morphology. Embryonic quail hearts were optically paced at 3 Hz (180 bpm, well above intrinsic rate 60-110 bpm) at stage 13 of development (3-4 weeks human) for 5 min. Pacing fatigued the heart and led to at least 1 h of increased regurgitant flow. Resultant morphological changes were quantified with OCT imaging at stage 19 (cardiac looping-4-5 weeks human) or stage 35 (4 chambered heart-8 weeks human). All paced embryos imaged at stage 19 displayed structural changes in cardiac cushions. The amount of regurgitant flow immediately after pacing was inversely correlated with cardiac cushion size 24-h post pacing (P value < .01). The embryos with the most regurgitant flow and smallest cushions after pacing had a decreased survival rate at 8 days (P < .05), indicating that those most severe endocardial cushion defects were lethal. Of the embryos that survived to stage 35, 17/18 exhibited CHDs including valve defects, ventricular septal defects, hypoplastic ventricles, and common AV canal. The data illustrate a strong inverse relationship in which regurgitant flow precedes abnormal and smaller cardiac cushions, resulting in the development of CHDs.

Quality of Life for Historic Cavopulmonary Shunt Survivors.

Beginning with Dr William Glenn in 1958, 90 patients with congenital heart lesions underwent cavopulmonary (Glenn) shunts over a 30-year period. In 2015, the follow-up data on this original cohort were reported. The study focuses on the current quality of life of this cohort. Of the original 91 cavopulmonary shunt survivors, 14 (ages: 26-59; average length of postsurgical follow-up: 38.4 years) completed the Rand 36-Item Short-Form Health Survey, volume 2 (SF-36v2) quality-of-life survey at clinical office visits, over the phone or via regular mail. Diagnoses included tricuspid atresia (n = 9), double inlet left ventricle (n = 1), d-transposition of great arteries (n = 1), Ebstein's anomaly (n = 1), tetralogy of Fallot (n = 1), and pulmonary atresia with hypoplastic right ventricle (n = 1). Norm-based comparison of cavopulmonary shunt survivors to the general population was performed using a one-sample t test. The 36-question health survey, SF-36v2, provided physical and mental health summary measures standardized to achieve a mean of 50. The 14 survivors' physical composite score was 47.18 (standard deviation [SD]: 8.24; P = .22) and mental composite score was 52.71 (SD: 5.64; P = .095). The cavopulmonary shunt is now a widely used surgical palliation for single-ventricle patients and can be associated with physical and mental health outcomes similar to the general US population. Cavopulmonary shunt survivors' SF-36v2 survey results do not demonstrate a statistically significant difference from the general US population in physical or mental health measures. The results of this study contribute to the discussion of quality of life for patients with congenital heart disease by following up with the oldest known survivors.

Legal Briefs: In Utero Cerebral Hemorrhage and Alloimmune Thrombocytopenia: Was It Preventable?

A 3,425-g, 39-week-gestation male infant was born to a 24-year-old gravida 1 para 0 woman via cesarean section because of a nonreassuring fetal heart rate tracing. Apgar scores were 9 and 9 at 1 and 5 minutes, respectively. He was admitted to the normal newborn nursery, where the nurse noted that he had generalized petechiae. The complete blood cell count was normal, except for a platelet count of 7 × 103/μL (7 × 109/L). He was admitted to the NICU at 27 hours of age for evaluation and care. He was alert and active, with normal blood pressure and vital signs. The neonatologist ruled out autoimmune thromobocytopenia after determining that the mother's platelet count was normal. He asked the obstetrician to order an antiplatelet antibody test on the mother to determine if alloimmune thrombocytopenia was the diagnosis. Intravenous immunoglobulin (IVIG) was given, as well as 2 random donor platelet transfusions, which moderately elevated the platelet count. Because a heart murmur was noted, cardiac ultrasonography was performed, which showed the infant to have a hypoplastic right ventricle, tricuspid atresia, a ventricular septal defect, and a patent foramen ovale. Prostaglandins were started and the infant was sent to a referral center, where a balloon septostomy was performed. The neonatologist at the referral hospital requested a hematology consultation and ordered a platelet antibody test; however, because it was the weekend, the test was deferred until the following Monday. By Monday, the platelet count was normal, and the hematologist wrote a note that alloimmune thrombocytopenia was probably not the cause and the test was never performed. The parents were told that the low platelet count was idiopathic, and because it resolved, nothing further needed to be done. The complex cardiac defect was subsequently repaired, with excellent results. The mother shared …

Staged Left Ventricular Recruitment and Biventricular Conversion for Patients With Borderline Left Heart

A borderline left heart may be present in patients with hypoplastic left heart syndrome or an unbalanced atrioventricular canal defect. Traditionally, such patients have been managed either by high-risk biventricular repair in infancy or during the neonatal period, or by definitive single-ventricle palliation. In this article, we present an approach for staged left ventricular recruitment that promotes gradual rehabilitation of left heart structures and allows delay in the commitment to either a single-ventricle pathway or a biventricular pathway. The rationale, techniques, and early results are described.

Abstract 18055: Induced Growth of Hypoplastic Cardiac Structures to Facilitate Repair of Congenital Defects

Introduction: Congenital heart defects (CHD) may include hypoplastic valves, ventricles and vessels which complicate repairs. Our hypotheses were that hypoplastic structures are developmental rather than primarily genetic in origin and the correct biomechanical signal would induce catch up growth. Our corollary hypothesis was that the growth signal is provided by flow, not pressure. First stage operations, therefore, were designed to increase flow and induce growth. Once growth was sufficient, a second operation would often complete the repair. We report our results using flow induced growth of hypoplastic structures to facilitate repair in 3 types of CHD. Methods: Three groups of CHD patients with associated hypoplastic structures: unbalanced atrioventricular canal defects (UAVC); pulmonary atresia with intact ventricular septum (PAIVS); and coarctation of the aorta (CoA) were reviewed. Operations increased flow through the hypoplastic structures, such as creating restrictive septal defects to increase flow through the hypoplastic AV valves and ventricles (UAVC, PAIVS) or relieving obstruction (CoA) to enhance aortic valve and arch flow. Results: On follow up, virtually all (85/90) hypoplastic structures reached normal size and the rest had nearly comparable growth (Table). Conclusions: 1) Operations designed to increase flow through hypoplastic structures reliably induced catch up growth of UAVC, PAIVS and CoA lesions. 2) The growth response supported underdevelopment as the cause of hypoplasia and flow as the growth signal to reverse it. 3) Growth induction allowed two ventricle repairs in UAVC and PAIVS patients and avoided extended arch repairs in CoA; all with decreased operative risk. 4) Following catch up growth of the hypoplastic lesions, the outlook improved to that of patients with balanced AVCs, normal sized RVs in pulmonary atresia and well repaired CoA. 5) Once normal size was reached growth continued, producing a durable result.

Novel pathological findings of placenta with fetal heart failure associated with congenital heart disease

Novel pathological findings of placenta with fetal heart failure associated with congenital heart disease

Cardiac abnormalities and Wolfram (DIDMOAD) syndrome: a case report

Cardiac abnormalities are very rarely reported to be associated with Wolfram (DIDMOAD) syndrome. We report a child who presented with cyanotic heart disease and was operated twice for cardiac lesion. At the age of 6 years, the case developed osmotic symptoms and, during evaluation, diabetes insipidus, optic atrophy and deafness were reported. DIDMOAD syndrome with atrial septal defect, severe pulmonary stenosis and hypoplastic right ventricle is not previously reported. In addition to our case, in a literature survey on all reported cases of DIDMOAD syndrome (more than 700), only 11 cases with cardiac abnormalities have been stated. Common abnormalities found are pulmonary stenosis, followed by tetralogy of Fallot and ventricular septal defects. Impact of DIDMOAD syndrome on cardiovascular development needs to be elucidated.

Fontan Physiology: Anaesthetic Implications for Non-Cardiac Surgery: A Case Report

Patients with congenital heart diseases are a growing population and noncardiac surgeries will become an important health care issue. Modification of surgical techniques and medical advances has improved the survival of patients with complex congenital cardiac abnormalities, resulting in more adult patients with fontan physiology presenting for non-cardiac surgery. The older fontan patient is at particular risk of thromboembolism, arrhythmias, progressive ventricular dysfunction, protein losing enteropathy and plastic bronchitis. Understanding the physiology of the fontan circulation is essential for the successful anaesthetic management of these patients. Anaesthesia should be administered only in a centre where the relevant cardiology and intensive care expertise are available. We report a case of fontan physiology in a 24 year old female patient who underwent sternal keloid revision under general anaesthesia. Case Report The hospital ethics committee granted approval for the publication of this case report and waiver of informed consent (CIRB Ref No: 2014/391/D). We report the anaesthetic management of a 24 year old female weighing 44 kg with a history of fontan's procedure in childhood who underwent sternal keloid revision under general anaesthesia. She was previously seen by the plastic surgeon for sternal keloid with recurrent infection and pus discharge for one year duration, with inadequate response to medical therapy. She was born with Pulmonary Atresia with Intact Ventricular Septum (PAIVS), large Atrial Septal Defect (ASD) and a hypoplastic right ventricle. She underwent a left Blalock-Tausig (BT) shunt procedure as a neonate. At three years of age, a modified fontan's procedure with BT shunt dissection, anastomosis between superior vena cava to the right pulmonary artery, lateral tunnel using gortex and over sewing of the Main Pulmonary Artery (MPA) was performed. Conversion to extra-cardiac fontan was done at 11 years of age. She was currently on Aspirin 100mg once a day, and on 6 monthly follow-up with her cardiologist. Functionally, she was independent in her activities of daily living, was able to tolerate physical activities up to a maximal effort tolerance of 4 (metabolic equivalents) METS, and did not have any symptoms of cardiovascular compromise. On examination, she was alert but very anxious, afebrile with a blood pressure of 116/74mmHg and heart rate 95 beats per minute. She had a grade 2 systolic murmur while the rest of the systemic examination was unremarkable. A keloid was present extending from the suprasternal notch to the xiphisternum. Preoperative investigations were unremarkable. Electrocardiogram (ECG) showed sinus rhythm. She was reviewed in the Adult Congenital Heart Disease (ACHD) clinic prior to the operation. Her perioperative cardiac risk was estimated to be moderate, and a 2D-echo was arranged on the morning of the operation day as her last 2D-echo was performed more than 2 years ago. Her 2-D echo showed a large ASD with unrestricted flow, inferior vena cava (IVC) fontan pathway patent with low velocity flow, superior vena cava (SVC) connection to pulmonary artery (PA) patent with low velocity flow, hypoplastic right ventricle with right ventricular systolic pressure of

Overlapping and Opposing Functions of G Protein-coupled Receptor Kinase 2 (GRK2) and GRK5 during Heart Development

G protein-coupled receptor kinases 2 (GRK2) and 5 (GRK5) are fundamental regulators of cardiac performance in adults but are less well characterized for their function in the hearts of embryos. GRK2 and -5 belong to different subfamilies and function as competitors in the control of certain receptors and signaling pathways. In this study, we used zebrafish to investigate whether the fish homologs of GRK2 and -5, Grk2/3 and Grk5, also have unique, complementary, or competitive roles during heart development. We found that they differentially regulate the heart rate of early embryos and equally facilitate heart function in older embryos and that both are required to develop proper cardiac morphology. A loss of Grk2/3 results in dilated atria and hypoplastic ventricles, and the hearts of embryos depleted in Grk5 present with a generalized atrophy. This Grk5 morphant phenotype was associated with an overall decrease of early cardiac progenitors as well as a reduction in the area occupied by myocardial progenitor cells. In the case of Grk2/3, the progenitor decrease was confined to a subset of precursor cells with a committed ventricular fate. We attempted to rescue the GRK loss-of-function heart phenotypes by downstream activation of Hedgehog signaling. The Grk2/3 loss-of-function embryos were rescued by this approach, but Grk5 embryos failed to respond. In summary, we found that GRK2 and GRK5 control cardiac function as well as morphogenesis during development although with different morphological outcomes.

Abstract 167: Growth Induction to Reverse Congenital Aortic Developmental Hypoplasia

Objectives: Congenital heart disease may include hypoplastic heart valves, ventricles or great arteries. Infants with coarctation of the aorta (CoA) often have a hypoplastic transverse aortic arch (TAA) which can greatly complicate surgical repairs. Although these defects are often considered to be genetic in origin, our hypothesis was that they are problems of development which are potentially reversible. We tested the corollary hypothesis that hypoplastic TAAs retain normal developmental potential and the increased aortic flow after CoA repair provides the biomechanical signal for catch-up growth. Methods: Infants (N = 19) with TAA hypoplasia who underwent surgical CoA repair were studied for TAA growth by echocardiography done prior to and at intervals up to 13 years later. The TAA diameters were indexed using nomograms and calculated as standard deviations from expected size (SDE). Normal range is ± 2 SDE and &lt; −2 indicates hypoplasia. Results: 1) TAA growth was rapid and significant within 3 months. 2) The initial average TAA SDE = −3.7 (range: −7.6 to −2.1) (0/19 normal); 3 months = −1.5 (-4.1 to 0.9) (12/17); 1 year = −1.0 (-4.2 to 1.3) (15/19); 5 to 13 years = −0.6 (-2.1 to 0.9) (16/17 normal). Conclusions: 1) Hypoplastic aortic arches grew rapidly to normal size with increased flow following CoA repair. 2) The results suggest the cause of hypoplasia was underdevelopment from low flow and, when increased, flow provided the biomechanical signal to induce catch up growth. 3) Infants were a relevant model for demonstrating the aortic growth signal. 4) Growth induction by increased blood flow could be used to reverse aortic underdevelopment in other selected patients.

The new concept of univentricular heart.

The concept of univentricular heart moved from hearts with only one ventricle connected with atria [double inlet ventricle or absent atrioventricular (AV) connection] to hearts not amenable to biventricular repair, namely hearts with two ventricles unable to sustain separately pulmonary and systemic circulations in sequence. In the latter definition, even hearts with one hypoplastic ventricle are considered “functional” univentricular hearts. They include pulmonary/aortic atresia or severe stenosis with hypoplastic ventricle, and rare conditions like huge intramural cardiac tumors and Ebstein anomaly with extreme atrialization of right ventricular cavity. In this setting, the surgical repair is univentricular with “Fontan” operation, bypassing the ventricular mass. In other words, functionally univentricular heart is a condition in which, after surgery, only one ventricle sustain systemic circulation. Univentricular hearts (double inlet or absent AV connection) almost invariably show two ventricular chambers, one main and one accessory, which lacks an inlet portion. The latter is located posteriorly when morphologically left and anteriorly when morphologically right. As far as double inlet left ventricle, this is usually associated with discordant ventriculo-arterial (VA) connection (transposition of the great arteries) and all the blood flow to the aorta, which takes origin from the hypoplastic anterior right ventricle, is ventricular septal defect (bulbo-ventricular foramen) dependent. If restrictive, an aortic arch obstruction may be present. Double inlet left ventricle may be rarely associated with VA concordance (Holmes heart). As far as double inlet right ventricle with posterior hypoplastic left ventricular cavity, ventriculo-arterial connection is usually of double outlet type; thus the term double inlet–outlet right ventricle may be coined. Absent right or left AV connection may develop in the setting of both d- or l-loop, whatever the situs. In this condition, the contra-lateral patent AV valve may be either mitral or tricuspid in terms of morphology and the underlying ventricle (main chamber) either morphologically left or right. Establishing the loop, whatever right or left (also called right or left ventricular topology), is a fundamental step in the segmental-sequential analysis of congenital heart disease.

Ultrasound Meets Magnetic Resonance Imaging in the Diagnosis of Pentalogy of Cantrell with Complete Ectopy of the Heart

We report a case of a complete pentalogy of Cantrell at 25 weeks of gestation through antenatal Two Dimensional (2D) and Three Dimensional (3D) ultrasound and fetal Magnetic Resonance Imaging (MRI). A complete ectopiacordis and a supraumbilical hepato-omphalocele were diagnosed. Echocardiography showed multiples cardiac anomalies: a large ventricular septum defect, a hypoplastic right ventricle, a transposition of the great vessels with a small right outflow. Prenatal and post mortem MRI and 3D Computed Tomography (CT) were performed in addition to routine 2D ultrasound to enhance the visualization of fetal anomalies for accurate diagnosis. Fetal autopsy following termination of the pregnancy confirmed the presence of all malformations detected prenatally. In our opinion extensive imaging of cardiac, thoracic and abdominal malformations by ultrasound and MRI is complementary for a clear diagnosis and counseling of the patient.

Abnormal left ventricular diastolic function at late follow-up after repair of total anomalous pulmonary venous drainage: The impact of altered ventricular loading in utero

Assessment of diastolic function has not been described after repair of total anomalous pulmonary venous drainage (TAPVD), but studies of exercise capacity demonstrate impaired performance in this population despite normal systolic function. We postulated that diastolic impairment might contribute to this finding. We analyzed echocardiographic variables from 28 patients with repaired TAPVD and compared these with data from 32 healthy controls (normals) and 21 subjects with repaired transposition of the great arteries (TGA). Left ventricular (LV) end-diastolic volumes were smaller in the TAPVD group (median, 50 mL/m(2) compared with a median of 64 mL/m(2) in TGA and 67 mL/m(2) in normals; P<.001 in each case). LV diastolic function in the TAPVD group was impaired. Mitral early to late ratio was increased (median, 2.7 in TAPVD compared with a median of 1.9 in TGA [P=.047] and 2.1 in normals [P=.021]). LV isovolumic relaxation time was reduced (median, 50 milliseconds in TAPVD compared with a median of 70 milliseconds in both TGA and normals; P<.001 in each case). Late diastolic and systolic tissue Doppler velocities were lower and the E/e' ratio was higher in the TAPVD group. Patients with repaired TAPVD are usually regarded as having excellent outcomes, but the finding of LV diastolic dysfunction in this population warrants more careful follow-up. We postulate that the diastolic impairment in these patients is the result of relative unloading of the LV during early cardiac development. Thesefindings may also have implications in considering therapeutic approaches for hypoplastic ventricles in attempting to achieve biventricular repair.

Chick embryonic model of hypoplastic left heart syndrome: endocardial fibroelastosis

Endocardial Fibroelastosis (EFE) is a diffuse thickening of the ventricular endocardium, causing myocardial dysfunction and presenting as unexplained heart failure in infants and children. Its frequent association with Hypoplastic Left Heart Syndrome (HLHS) lead us to hypothesize abnormal hemodynamic loading is an important factor in its pathogenesis. We have used a chick model of HLHS induced by Left Atrial Ligation (LAL) at Embryonic Day (ED) 4. At ED8 and 12 modifications of myocardial architecture and fibrosis were studied by histology and immunoconfocal microscopy, in sham operated hearts and those with established HLHS phenotype, defined as apex-forming right ventricle. The amount of collagen was quantified by image analysis. Histology with H&E/Alcian Blue staining did not reveal any significant fibrosis in the LAL hearts with the exception of cardiac skeleton and valves. Immunohistochemistry with collagen I and periostin antibody clearly showed a thickening of the layer of subendocardial fibrous tissue. Quantification of staining area normalized by endocardial circumference showed a significant increase at ED12, but not ED8 in the LAL group. Staining intensity of myocardial markers (myosin heavy chain, MF20) was decreased in the hypoplastic ventricle. We are currently investigating whether increased tissue hypoxia plays a role in pathogenesis of these changes. We conclude that abnormal hemodynamic loading stimulates fibrous production in the subendocardium of the hypoplastic left ventricle. Therefore, EFE in HLHS clearly appears to be a secondary effect of altered hemodynamics.

Two-ventricle repairs in the unbalanced atrioventricular canal defect spectrum with midterm follow-up

Unbalanced atrioventricular (AV) canal defects include a hypoplastic ventricle (HV) and AV valve (HAVV) precluding complete 2-ventricle repairs (2VRs). Catch-up growth would solve this problem and was induced by increasing HAVV flow. The objectives were to assess reliability of HV and HAVV growth and provide 5- to 15-year 2VR follow-up. From 1990 to 2005, 23 consecutive infants (13 females and 10 males) with echo-diagnosed unbalanced AV canal defects (n=20) or subsets (n=3) underwent 2VRs. HV volumes (18 left and 5 right) and HAVV sizes estimated from biplane echoes and z values (standard deviation from expected) were determined. Hypoplasia was defined by a z value of less than -2.0. Three operative approaches were used: (1) Staged repairs (n=9) had complete AVV repairs with partial atrial septal defect and ventricular septal defect closures, which increased HAVV flow and maintained stability. The septal defects were closed later. (2) An asymmetric valve partition (n=8) was used to increase HAVV size. (3) For moderate hypoplasia, HAVV flow was increased and ASDs/VSDs were left for stability (n=6). Follow-up at 5 to 19 years was done locally. Staged repairs began at 20 to 328 days (average, 129 days) and were completed 5 to 145 days later (average, 101 days). Midterm survival was 87% (20/23) after 1 central nervous system bleed after trial weaning from extracorporeal membrane oxygenation and 2 later deaths from hyperkalemia. Reoperations for AVV regurgitation (n=3), AVV stenosis (n=1), and mitral valve replacement (n=1) were satisfactory. On follow-up, all hypoplastic structures (HV and HAVV) had grown to normal size. Two patients "doing well" were lost to follow-up. Survivors have satisfactory 2VRs, with 15 of 18 taking no cardiac failure medications. Reliable HV/HAVV catch-up growth was induced, and all midterm 2VRs were satisfactory.

Atrioventricular septal defect with an imperforate right-sided component of the common atrioventricular valve: anatomic and embryologic considerations

We describe an atypical case of an atrioventricular septal defect with a common atrioventricular junction in which the right-sided component of the common atrioventricular valve was imperforate, producing tricuspid atresia with a severely hypoplastic right ventricle and an ostium primum defect. We discuss the implications of the anatomic findings with regard to concepts of cardiac development, drawing a comparison with similar cases previously reported.

First Report of Atretic Coronary Sinus Stenting in a 5-kg Infant Resulting in Dramatic Improvement of Ventricular Function in Functional Single Ventricle

The patient was a male infant with L-transposition of great arteries (L-TGA), Ebstein's anomaly of the tricuspid valve, subvalvar aortic stenosis, ventricular septal defect (VSD), hypoplastic right ventricle, arch hypoplasia, and congenital complete heart block. He underwent a Norwood procedure, aortic arch repair, permanent pacemaker implantation, and a 3.5-mm aortopulmonary shunt at 4 days of age. At the time of his surgery, left ventricular function was in the normal range (ejection fraction [EF] = 67%). However by 3 months of age, he was noted to have developed moderate-severe biventricular dysfunction (left ventricular ejection fraction [LVEF] = 34%). Atresia of the coronary sinus with a small left superior venacava (LSVC) and a bridging vein was discovered during cardiac catheterization at this time. The coronary sinus mean pressure was 17 mm Hg, and the common atrial mean pressure was 6 mmHg. We opened the atretic coronary sinus ostium using radiofrequency ablation and stent placement. There was dramatic improvement in ventricular function observed over a 2-month period. Follow-up cardiac catheterization 5 months later revealed the stent in the coronary sinus to be widely patent with no intimal buildup, and the ventricular function was normal (LVEF = 58%). The patient had a bidirectional Glenn procedure with an uncomplicated postoperative course and is currently awaiting Fontan completion.