Mutations in HYAL2, Encoding Hyaluronidase 2, Cause a Syndrome of Orofacial Clefting and Cor Triatriatum Sinister in Humans and Mice.

Orofacial clefting is amongst the most common of birth defects, with both genetic and environmental components. Although numerous studies have been undertaken to investigate the complexities of the genetic etiology of this heterogeneous condition, this factor remains incompletely understood. Here, we describe mutations in the HYAL2 gene as a cause of syndromic orofacial clefting. HYAL2, encoding hyaluronidase 2, degrades extracellular hyaluronan, a critical component of the developing heart and palatal shelf matrix. Transfection assays demonstrated that the gene mutations destabilize the molecule, dramatically reducing HYAL2 protein levels. Consistent with the clinical presentation in affected individuals, investigations of Hyal2-/- mice revealed craniofacial abnormalities, including submucosal cleft palate. In addition, cor triatriatum sinister and hearing loss, identified in a proportion of Hyal2-/- mice, were also found as incompletely penetrant features in affected humans. Taken together our findings identify a new genetic cause of orofacial clefting in humans and mice, and define the first molecular cause of human cor triatriatum sinister, illustrating the fundamental importance of HYAL2 and hyaluronan turnover for normal human and mouse development.

Cor triatriatum sinister: a case series.

OBJECTIVE: As a highly rare congenital defect, cor triatriatum sinister represents only 0.1% of congenital cardiac anomalies. Depending on the degree of obstruction and the accompanying symptoms, cor triatriatum can be diagnosed at any age. This case series described 5 patients with cor triatriatum sinister who underwent operation. METHODS: Five patients with cor triatriatum sinister were seen at our institution between 2007 and 2013. The demographic characteristics and surgical results of these patients are outlined in this retrospective review. RESULTS: The surgical approach consists of left or right atriotomy, excision of the obstructing membrane, and repair of the associated intracardiac anomalies. After an uneventful postoperative hospital stay, all patients were discharged 5-10 days postoperatively. There were no instances of recurrent constriction after surgical treatment of the cor triatriatum membrane. Patients were followed up for a median of 4 years and were symptom free. CONCLUSION: In the surgical management of this easily and fully treatable congenital cardiac anomaly, it is difficult to determine which atriotomy approach is comparatively more advantageous. However, in the management of cor triatriatum sinister, priority should be given to confirmation of the diagnosis and full resection of the membrane. Thus, the surgeon should not hesitate to perform additional incisions if deemed necessary.

Cor triatriatum or divided atriums: which approach provides the better understanding?

It is frequent, in the current era, to encounter congenital cardiac malformations described in terms of "cor triatriatum". But can hearts be truly found with three atrial chambers? The morphological method, emphasised by Van Praagh et al, states that structures within the heart should be defined on the basis of their most constant components. In the atrial chambers, it is the appendages that are the most constant components, and to the best of our knowledge, hearts can only possess two appendages, which can be of either right or left morphology. The hearts described on the basis of "cor triatriatum", nonetheless, can also be analysed on the basis of division of either the morphologically right or the morphologically left atriums. In this review, we provide a description of cardiac embryology, showing how each of the atrial chambers possesses part of the embryological body, along with an appendage, a vestibule, a venous component, and a septum that separates them. We then show how it is, indeed, the case that the hearts described in terms of "cor triatriatum" can be readily understood on the basis of division of these atrial components. In the right atrium, it is the venous valves that divide the chamber. In the left atrium, it is harder to provide an explanation for the shelf that produces atrial division. We also contrast the classic examples of the divided atrial chambers with the vestibular shelf that produces supravalvar stenosis in the morphologically left atrium, showing that this form of obstruction needs to be distinguished from the fibrous shelves producing intravalvar obstruction.

Cardiac Anomalies in Two White-Tailed Eagles (Haliaeetus albicilla) in Sweden.

Severe cardiomegaly with an atrial septal defect was discovered during necropsy of a subadult White-tailed Eagle (Haliaeetus albicilla) found dead in the wild. A thin membrane composed of fibromuscular tissue separated the left atrium into two chambers, most consistent with that described for cor triatriatum sinister (CTS) in other species. Seventeen months later, necropsy of an adult White-tailed Eagle again revealed CTS. This lesion has not been reported previously in raptors.

Cor Triatriatum Sinister (Divided Left Atrium): Histopathologic Features and Clinical Management.

BACKGROUND: Cor triatriatum sinister (CTS), or divided left atrium, is a rare congenital cardiac disease in which the left atrium is divided into 2 chambers by a fibromuscular diaphragm that will cause blood flow obstruction to the left ventricle. Recent animal studies suggested the role of hyaluronidase-2 (HYAL-2) deficiency as a risk factor for developing CTS. The histopathologic features of this diaphragm and our surgical experience with the management of this disease are reviewed. METHODS: Ten patients underwent surgical correction of CTS between 2010 and 2018. All patients had complete clinical and imaging evaluation. The fibromuscular diaphragms were histologically evaluated with myosin, troponin, vimentin, smooth muscle actin, and HYAL-2 to characterize the structure of the CTS diaphragm. RESULTS: All patients underwent excision of CTS diaphragm using cardiopulmonary bypass with no early mortality. Most patients had the classic form of CTS in which the diaphragm separates the pulmonary and the vestibular chambers with no atrial septal defect. The histologic studies demonstrated the presence of fibrous, mesenchymal cells, along with cardiac muscle cells, at the site of membrane attachments. HYAL-2 enzyme was expressed in the CTS diaphragm. CONCLUSIONS: Surgical repair of CTS provides satisfactory results with low risk of death. Our histologic studies revealed the cellular composition of the CTS diaphragm. HYAL-2 deficiency may not explain the pathogenesis of CTS, and further studies are needed to evaluate the complex mechanisms involved in the development of this disease.

Bidirectional flow across a perforate cor triatriatum dexter in a dog with concurrent pulmonary, tricuspid, and mitral valve dysplasia.

A 10-week-old male intact mixed breed dog presented for evaluation of suspected right-sided congestive heart failure. Echocardiographic imaging revealed a perforate cor triatriatum dexter (CTD), along with pulmonary valve stenosis and tricuspid and mitral valve dysplasia. In typical CTD cases, there is unidirectional blood flow across the dividing membrane, from the caudal into the cranial right atrial chambers. Owing to right-sided pressure alterations caused by the concurrent valvar defects, color Doppler imaging demonstrated bidirectional flow across the CTD membrane.

Coexistence of coronary cameral fistulae and cor triatriatum sinister in an elderly patient.

Coronary cameral fistulae are unusual congenital or acquired anomalous communications between an epicardial coronary artery and a cardiac chamber. There are no reported cases of the association of coronary cameral fistulae and cor triatriatum, a rare congenital cardiac anomaly in which a fibromuscular membrane divides the left atrium into two chambers. We report the case of an 82-year-old man presenting with recurrent anterior chest pain. Echocardiographic examination identified non-obstructive cor triatriatum, mitral valve prolapse resulting in significant mitral regurgitation, dilated coronary arteries, and established the entry site of coronary artery fistulae at the apex of the left ventricle (Figure 1). Coronary angiography confirmed the existence of a plexiform fistula between the left anterior descending coronary artery and the left ventricle. Tetrofosmine scintigraphy revealed the presence of stress-induced ischaemia in the apex. To our knowledge, we report the oldest person with coronary cameral fistulae presenting with angina only at this stage, and the interesting case of the coexistence of two, although unconnected, congenital conditions in an elderly patient. In addition, this report highlights the important role of transthoracic and transoesophageal echocardiography to the characterization of these unusual anomalies, and the complementary information offered by three-dimensional transthoracic echocardiography.

Radical repair of cor triatriatum with partially unroofed coronary sinus and persistent left superior vena cava 35 years after operation for tetralogy of Fallot.

We report a rare case of simultaneous repair for Cor triatriatum (CT), partially unroofed coronary sinus (CS) with persistent left superior vena cava (PLSVC), moderately severe tricuspid regurgitation, and atrial flutter 35 years after radical operation for tetralogy of Fallot (TOF). A 40-year-old woman underwent patch closure of atrial septal defect as to drain blood from left SVC to right atrium (RA), excision of diaphragm in left atrium (LA), tricuspid annuloplasty, and cryoablation. Postoperative course was uneventful with successful anatomical correction.

[Myxoma of the cor triatriatum].

We present a rare case of myxoma in a patient with cor triatriatum. This pathology was symptomless and was revealed at transthoracic echocardiographic examination in a patient with ischemic heart disease. The patient was successfully subjected to surgery which consisted in removal of the tumor together with accessory membrane to which myxoma was attached and reconstruction of the atrial wall. In international medical literature we found no communication on the combination of myxoma with cor triatriatum.

[Subtotal cor triatriatum sinister associated with bilateral partial anomalous pulmonary venous return]. / Iki tarafli anormal kismi pulmoner venöz dönüs anomalisi birlikteliginde subtotal kor triatriatum sinister.

Cor triatriatum sinister is a rare congenital cardiac pathology, representing only 0.1% of congenital cardiac anomalies, and often associated with other cardiac defects. In classic cor triatriatum sinister, the pulmonary venous chamber receives all pulmonary veins and drains into the left atrium through a variable-sized orifice. The case of a 4-month-old male patient who had subtotal cor triatriatum sinister associated with right and left upper anomalous pulmonary venous return is presented.

Cor triatriatum dexter: two-dimensional echocardiographic diagnosis.

Cor triatriatum dexter is a malformation resulting from lack of normal regression of the embryonic right valve of the sinus venosus. In this situation, the right atrium is divided by a membrane into two chambers. Two-dimensional echocardiography was used in the antemortem diagnosis of this rare cardiac anomaly in a neonate. Associated cardiac lesions were also documented. The patient died, and findings were verified at autopsy.

Conditions with right ventricular pressure and volume overload, and a small left ventricle: "hypoplastic" left ventricle or simply a squashed ventricle?

OBJECTIVES: We modeled the utility of preoperative potential left ventricular (LV) volume in predicting postoperative volume in conditions causing LV compression. BACKGROUND: With right ventricular (RV) overload lesions, LV "hypoplasia" may be primarily due to compression by reverse septal bowing. If so, preoperative potential LV volume should correspond 1:1 with postoperative volume. The potential volume for a given endocardial circumference can be calculated from the maximal potential cross-sectional area (where A = circumference(2)/4pi) and LV length. METHODS: We studied echocardiographic variables from 22 patients with RV overload lesions perioperatively. RESULTS: Preoperative LV volume was 15.0 +/- 7.1 ml/m2 (59% of patients had a volume <15 ml/m2); potential volume was 20.0 +/- 9.8 ml/m2. Postoperative volume increased to 28.2 +/- 8.6 ml/m2 (100% of patients had a volume >15 ml/m2). Preoperative potential volume correlated well with, but generally underestimated, postoperative volume (r = 0.75, p < 0.0001). Postoperative increases in both LV circumference and length contributed to this discrepancy. CONCLUSIONS: In RV overload lesions, LV "hypoplasia" is primarily due not to compression; rather it is due to underfilling. Even "hypoplastic" ventricles can achieve an adequate cavity after operation normalizes loading conditions. Both true and potential preoperative volume can predict postoperative volume well. However, potential volume, which is less prone to underestimating ventricular adequacy, may better help to determine suitability for biventricular repair in lesions of RV overload associated with a "hypoplastic" LV.

Surgical correction of cor triatriatum sinister in the paediatric population: mid-term results in 15 cases.

OBJECTIVES: Cor triatriatum sinister (CTS) is a rare developmental cardiac abnormality resulting in left ventricular inflow obstruction. In this report, we aimed to present our mid-term results of early childhood patients operated for CTS and associated cardiac abnormalities. METHODS: We enrolled 15 patients with CTS who were operated by a single surgeon between 2001 and 2013. A retrospective analysis was performed in order to determine the demographics, operative and postoperative results of the patients. The median age was 14 months and the median body weight was 8.2 kg at the time of operation. RESULTS: Fourteen patients had concomitant cardiac pathology. Three of the patients had atrial septal defect and 1 of the patients had partial abnormal pulmonary venous connection, whereas 4 of the patients had both. In 2 cases of complete atrioventricular septal defect, 1 case with ventricular septal defect, 1 case with patent ductus arteriosus, 1 case with double outlet right ventricle and another case with tetralogy of Fallot, complete repair was performed together with membrane resection in the left atrium (LA). The mean preoperative left atrial gradient was 13.3 mmHg, whereas the mean LA pressure at the first postoperative year was 4.2 mmHg. There was 1 case with early mortality due to septic multiorgan failure secondary to pneumonia. CONCLUSIONS: CTS is a rare congenital cardiac anomaly in which the results of the corrective surgery are encouraging. Early and long-term outcomes may be variable according to the associated congenital heart defects.

Cor triatriatum dexter with anomalous pulmonary venous drainage and sinus venosus atrial septal defect.

The atypical location of a membrane in a case of cor triatriatum dexter prompted successful repair of accompanying anomalies, with in situ use of the membrane. The anatomy is described with a review of the literature.

Cor triatriatum. Clinical presentation and operative results.

From November 1973 to January 1988, 15 patients with cor triatriatum underwent surgical correction at the Department of Cardiac Surgery, Ospedali Riuniti, Bergamo, Italy. Their ages ranged from 15 days to 48 years. Eight patients (53%) were younger than age 1 year. Evidence of congestive heart failure was present in five infants, whereas three infants, three children, and two adults initially had signs of pulmonary venous obstruction, and two children had a heart murmur only. Five patients had cor triatriatum alone; in ten cases there also was an atrial septal defect. Associated anomalies in four patients included left superior vena cava, ventricular septal defect and left superior vena cava, partial anomalous pulmonary venous connection, and bilateral partial anomalous pulmonary venous connection. Cor triatriatum was repaired with the aid of cardiopulmonary bypass in all patients. Excision of the membrane was accomplished with a right atrial approach in 13 patients and a left atriotomy in one patient. Both atria were opened in one case. All associated anomalies were simultaneously corrected. Three patients (20%) died early after operation. Among the 12 survivors, no late events have occurred, and all of them are presently in New York Heart Association functional class I. A recent echocardiogram shows absence of residual obstruction or shunt and good development of the left cardiac chambers.