Mitral atresia with normal aortic valve: a study of eighteen cases and a review of the literature

Mitral Atresia with Normal Aortic Root

Mitral atresia with normal aortic root is a rare complex congenital heart defect (CHD) and constitute less than 1% of all CHDs. In this anomaly, the mitral valve is atretic, a patent foramen ovale provides egress of the left atrial blood, either a single ventricle or two ventricles with left ventricular hypoplasia are present, and the aortic valve/root are normal by definition. Clinical, roentgenographic and electrocardiographic features are non-distinctive, but echo-Doppler studies are useful in defining the anatomic and pathophysiologic components of this anomaly with rare need for other imaging studies. Treatment consists of addressing the pathophysiology resulting from defect and associated cardiac anomalies at the time of initial presentation, usually in the early infancy. These children eventually require staged total cavo-pulmonary connection (Fontan) in three stages. Discussion of each of these stages were presented. Complications are observed in-between the stages of Fontan surgery and following completion of Fontan procedure. Attempts to monitor for early detection of these complications and promptly addressing the complications are recommended.

Imaging characteristics and associations of left atrioventricular valve atresia and patent aortic root with isometric atrial appendages on multidetector CT

AIM

The present study sought to study the imaging associations of left atrioventricular valve (mitral) atresia and patent aortic root in patients with isomerism of atrial appendages as detected on multidetector computed tomography (CT) angiography MATERIALS AND METHODS: The CT angiography studies performed at a tertiary medical center from January 2014 to December 2021 were retrospectively evaluated to identify patients with left atrioventricular valve atresia and patent aortic root with isometric atrial chambers. The morphology of the atrial appendage and extent of pectinate muscles was used to identify the type of isomeric atrial chambers. A comprehensive assessment of discordant arrangement of organs and the variations in venoatrial connections was done.

RESULTS

Left atrioventricular valve atresia in the presence of patent aortic root and isomeric atrial appendages was identified in eight patients (four males). The mean age at diagnosis was 7 years. Right isomerism of the atrial appendages was seen in five patients while three patients had left isomerism. Disharmonious patterns of abdominal visceral arrangement were seen in two patients. Atrial and ventricular septal defects were seen in all patients. The most common pattern of ventricular arterial connection was DORV (double outlet right ventricle) (n = 4). While five patients had normally related great arteries, three had aorta anterior to the pulmonary trunk. Right ventricular outflow obstruction was seen in seven patients. Right aortic arch with mirror image branching was seen in four patients. Coronary artery anomalies were seen in four patients.

CONCLUSIONS

The presence of left atrioventricular valve atresia and patent aortic root with isomeric atrial appendages is a rare congenital anomaly frequently associated with anomalous systemic and pulmonary drainage, conotruncal anomalies, and right ventricular outflow obstruction. Hence, comprehensive CT-based evaluation is indispensable in providing detailed anatomy and aids in presurgical planning.

Imaging characteristics and associations of left atrioventricular valve atresia and patent aortic root with lateralized atrial chambers on multidetector CT

AIM

To study the imaging characteristics and the associations of left atrioventricular valve atresia with patent aortic root and lateralized atrial chambers on multidetector computed tomography (CT) angiography.

MATERIALS AND METHODS

We retrospectively evaluated all the CT angiography studies performed for the evaluation of various congenital heart diseases at our center from January 2014 to December 2021. Cases with left atrioventricular valve atresia and patent aortic root with lateralized atrial chambers were identified. The types of cardiovascular involvement as identifiable on CT angiography were studied and compiled.

RESULTS

A total of 38 patients with left atrioventricular valve atresia and patent aortic root were included (median age: 5 months, males: 31). A total of 89.5% had usual atrial arrangement and 10.5% had mirror imagery of atria. Normal drainage of right and left superior caval veins and inferior caval vein into systemic venous atrium was seen in 77.8%, 61.5%, and 86.6%, respectively. Anomalous pulmonary venous drainage was seen in 3 (7.9%) patients. Atrial and ventricular septal defects were the most common associations. Imperforate left atrioventricular membrane was seen in 9 (23.7%) patients and absent left atrioventricular connection in 27 (71.1%). Discordant right atrioventricular connection was seen in 5 (13.1%) patients. While a double outlet right ventricle (76.3%) was the most common ventriculoarterial connection, discordant ventriculo-arterial connection (transposition) in 4 (10.5%). Most patients had good sized pulmonary arteries. Patent arterial duct and right aortic arch were seen in 29% and 21%, respectively. Aberrant right subclavian artery was the most common arch vessel anomaly. Coronary anomalies were seen in 7 patients (19%); single coronary artery being the most common.

CONCLUSIONS

Majority of the patients with left atrioventricular valve atresia and patent aortic root with lateralized atrial chambers have usual atrial arrangement, normal right atrioventricular connections and a double outlet configuration of the right ventricle. Absent left atrioventricular connection is a more common than imperforate left atrioventricular valve membrane. Atrial and ventricular septal defects are the most common associations. Comprehensive CT based evaluation of vascular and nonvascular thoracic structures is imperative before surgery or interventions in patients with mitral atresia.

Mitral atresia with transposed great arteries and normal semilunar valves: a rare combination

Mitral atresia is commonly seen as a part of the spectrum of hypoplastic left heart syndrome, and it is usually associated with multiple levels of systemic outflow tract obstruction. Isolated mitral atresia with a normal aortic valve is extremely rare. We report the rare combination of mitral atresia, transposition of the great arteries, and unobstructed systemic and pulmonary blood flow.

Mitral Atresia with Hypoplastic Left Ventricle and Multiple Shunt Lesions

Mitral atresia is a rare congenital heart defect when compared to atresia of other valves and it is often associated with other cardiac malformation such as patent ductus arteriosus, coarctation of the aorta, transposition of the great arteries, pulmonary stenosis, shunt defects, cor triatriatum, chamber, and valvular anomalies. There have been few reports of mitral atresia, therefore, the case of a 5-month-old male child with complaint of difficulty with breathing and echocardiographic diagnosis of atretic mitral valves, atrial septal defect of 15 mms, ventricular septal defect (VSD) of 10 mms and hypoplastic left ventricle is reported.

Atresia of the left atrioventricular valve with patency of the aorta: anatomico-functional analysis of 23 patients

We analyzed the findings in 23 patients with atresia of the left atrioventricular valve and a patent aorta seen in the period from January 1980 to July 1989. Having divided the cases according to the anatomical findings, we made a subsequent analysis of the clinical and surgical results with the aim of establishing the management most likely to diminish risks, still high, in treatment of this complex anomaly. From the anatomical viewpoint, three variants were observed. In the first, made up of 15 cases, there was absence of the left atrioventricular connexion. The characteristic finding in the second group, with five cases, was an imperforate left atrioventricular valve in the setting of concordant atrioventricular connexions. The third group, of these cases, was dominated by the presence of isomerism of the atrial appendages, both appendages being of left morphology in one case, and of right morphology in the other two. Further anatomical variation was then found in each group. Nine of the 15 with absence of the left atrioventricular connexion had the right atrium connected to a dominant left ventricle in presence of a rudimentary and incomplete right ventricle associated with discordant ventriculo-arterial connexions, all of them being in usual atrial arrangement and three with pulmonary stenosis. The remaining six in this first variant had the right atrium connected to a dominant right ventricle. In the five patients with imperforate left atrioventricular valves, two had discordant and three had concordant ventriculo-arterial connexions. In the three cases with isomerism, two had absence of the left atrioventricular connexion, with a dominant right ventricle. The last patient had an imperforate left atrioventricular valve and a discordant ventriculo-arterial connexion. From the functional viewpoint, there were 14 patients (10 with absence of an atrioventricular connexion, four with imperforate atrioventricular valve) with congestive heart failure and nine patients (five from the first, one from second, and three from the third variant) with hypoxia. Long-term follow-up (median 16.4 months--varying from 1 to 41 months--in the group with congestion and 27.7 months--varying from 12 to 57 months--in those with hypoxia) showed favorable clinical evolution in 11 (91%). We conclude that an anatomico-functional division can point towards the most appropriate management in this complex anomaly.

Absence of the aortic valve cusps with mitral atresia, normal left ventricle, and intact ventricular septum

A case of a previously unreported anomaly is presented in which absence of the aortic valve cusps, mitral atresia, a normal left ventricle, and an intact ventricular septum were diagnosed by cross sectional echocardiography. The development of a normal left ventricle, rather than the hypoplastic ventricle usually associated with mitral atresia, is explained by filling of the ventricular cavity via the regurgitant aortic valve.

Extraatrial interatrial duct and reestablishment of aortopulmonary communication by enlarging the aortic arch. Experimental development of two surgical techniques for hypoplastic left heart syndrome palliation without extracorporeal circulation

A new surgical procedure is presented for palliation of hypoplastic left heart syndrome. The first palliative technique consists of creation of an extraatrial interatrial duct and the second, reestablishment of the aortopulmonary communication by enlarging the aortic arch with a "conduit patch". Both procedures avoid having to clamp small systemic vessels and pulmonary veins and extracorporeal circulation is not needed. Extraatrial interatrial ducts were created in 10 dogs and the effectiveness of the procedure was evaluated. Reestablishment of the aorto-pulmonary communication and enlargement of the aortic arch was done in 7 specimens from patients with hypoplastic left heart syndrome who had died in the first hours of life and in 8 dogs. The surgical procedures, their advantages and the results obtained are described.

Creation and maintenance of an adequate interatrial communication in left atrioventricular valve atresia or stenosis

Patients with left atrioventricular (AV) valve atresia or stenosis were studied retrospectively to determine the incidence of early and late failures of procedures to enlarge an interatrial communication. The 61 patients underwent 80 procedures: 5 balloon atrial septostomies, 12 blade atrial septostomies and 63 surgical septectomies. No balloon septostomy provided adequate long-term palliation. Of 12 blade septostomies, 4 resulted in gradients across the atrial septum of 5 to 8 mm Hg and 8 in gradients 3 mm Hg or less. Results from blade septostomy were unrelated to underlying diagnosis, age, gradient before the procedure, number of previous procedures, pulmonary blood flow or size of the postprocedure defect by balloon sizing, but were related to size of the postoperative defect estimated by echocardiography. Among 8 patients with gradients of 3 mm Hg or less after blade septostomy, 7 were followed 9 +/- 7 months and showed no evidence of restenosis. Of 63 surgical septectomies, 11 (17.5%) were inadequate, and in at least 7 cases the failure was due to restenosis of the defect as documented by serial catheterizations or echocardiograms. Outcome after surgical septectomy was unrelated to underlying diagnosis, age or number of previous procedures, but was related to size of the defect created. Our results reveal improved results in terms of residual gradient for blade septostomy compared with previous studies and the need to follow these patients carefully, even those undergoing surgical septectomy.

Progressive obstruction of the foramen ovale in patients with left atrioventricular valve atresia

Thirteen patients with left atrioventricular (AV) valve atresia and a normal aortic root were studied to evaluate the status of the interatrial communication with advancing age. Six patients had cardiac catheterization within the first 2 weeks of age; of these, five had repeat studies before 7 months of age. The seven other patients initially underwent catheterization after 2 weeks of age. In the group with catheterization before 2 weeks of age, the mean left atrial pressure was 7.8 +/- 5.5 mm Hg and the left atrial-right atrial mean pressure gradient was 1.7 +/- 2.4 mm Hg. In the combined group of patients with catheterization after 2 weeks of age, the mean left atrial pressure was 25.9 +/- 5.6 mm Hg and the mean left atrial-right atrial pressure gradient was 21.1 +/- 5.1 mm Hg. Seven of the 13 patients have survived and have now reached a median age of 6.5 years. Balloon atrial septostomy was adequate for long-term survival in one patient; all of the others have required surgical atrial septectomy. Progressive obstruction of the foramen ovale is part of the natural history of left AV valve atresia, and obstruction develops despite the absence of a left atrial-right atrial gradient during newborn study. Balloon atrial septostomy is recommended during the neonatal period in all patients with left AV valve atresia, even in the absence of an interatrial gradient. Because early surgical atrial septectomy is usually necessary for long-term survival, these patients should have serial noninvasive evaluation of the patency of the interatrial communication.

Recognition of imperforate atrioventricular valves by two dimensional echocardiography

The majority of hearts in which selective right or left atrial angiography shows no direct communication between one atrium and a ventricular chamber are considered to be examples of atresia of the right or left atrioventricular valves. Most patients presenting with the clinical features of tricuspid atresia have an absent right atrioventricular connection, while those with features of mitral atresia and a normal aortic root frequently have an absent left atrioventricular connection. By studying 67 patients using two dimensional echocardiography we have identified 12 in whom there was an imperforate atrioventricular valve and not an absent atrioventricular connection. Thus, in 44 hearts with the angiographic features of tricuspid atresia, 36 had absence of the right atrioventricular connection and six had an imperforate right atrioventricular valve. In the latter, four were examples of atrioventricular concordance and two were univentricular hearts of left ventricular morphology in which the mode of atrioventricular connection was through one perforate and one imperforate valve. Similarly, 17 out of 23 cases of mitral atresia had absence of the left atrioventricular connection. The remaining six had an imperforate left atrioventricular valve which was associated with atrioventricular concordance in two patients and with double inlet univentricular heats in four patients.

Echocardiographic assessment of the aortic root in syndromes with left ventricular hypoplasia

Echocardiograms and angiograms of six infants with left ventricular hypoplasia were examined. Three observations were made: (1) A normal-sized aortic root echogram may be seen in infants with mitral atresia, intact ventricular septum and normally related great arteries. (2) A recognizable mitral valve echogram may be seen in mitral atresia. (3) The true echocardiographic left ventricular dimension may be exceedingly difficult to measure, the tendency being to overestimate it. Awareness of these pitfalls with aid in the echocardiographic diagnosis of left ventricular hypoplasia in infants.

Two-dimensional echocardiographic assessment of common atrioventricular valves in univentricular hearts

Twelve patients with univentricular heart and common atrioventricular valve were identified by two-dimensional echocardiography. Seven had an ostium primum atrial septal defect and five a common atrium. The common atrioventricular valve had the appearance of a free floating anterior leaflet flanked by two lateral leaflets. The position of the rudimentary chamber in relation to the atrioventricular valve was posterior in six and anterior in two; no chamber was identified in four. Two-dimensional echocardiography provides a reliable method for the identification of common atrioventricular valve in univentricular heart.

Left atrial to coronary sinus fenestration (partially unroofed coronary sinus). Morphological and angiocardiographic observations

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Atresia of left atrioventricular orifice. Anatomical investigation in 62 cases

Sixty-two hearts without a patent exit from the left atrium to the ventricular mass have been studied. All had situs solitus and laevocardia. The material consisted of 32 cases with coexistent aortic atresia and 30 cases with patent aortic root. Five hearts with aortic atresia were biventricular with atrioventricular concordance and imperforate left atrioventricular valves, and 27 hearts were univentricular of right ventricular type, with absent left atrioventricular connection. The anatomy of this group was uniform, with extreme hypoplasia of all the left cardiac segments. Among the cases with patent aortic root, five were biventricular, with atrioventricular concordance and imperforate left atrioventricular valves, and 24 had absent left atrioventricular connection, 15 with univentricular heart of right ventricular type and nine with univentricular heart of left ventricular type. The final heart had double inlet univentricular of left ventricular type with an imperforate left atrioventricular valve. In this second group the aorta was larger in cases with discordant ventriculoarterial connection or in those with double outlet from the main ventricular chamber. A normal sized aorta without aortic arch obstruction was observed in nine instances. These are of great interest in terms of surgical anatomy since definitive palliation may be feasible.

Univentricular heart of right ventricular type: clinical, angiographic and electocardiographic features

The sequential chamber analysis and angiographic, hemodynamic and clinical features, including those seen on electrocardiography, are presented in 18 patients with a univentricular heart of right ventricular type. In all cases a main chamber with a right ventricular trabecular pattern received both (or the sole) atrioventricular (A-V) connections, and a rudimentary chamber with a left ventricular trabecular pattern receiving no A-V connection was also present. The 18 patients were seen between 1971 and 1979; 6 died and the diagnosis was confirmed at autopsy. Twelve patients had double inlet, four absent right and two absent left A-V connections. Electrocardiography revealed right ventricular hypertrophy in all, and 11 had a superior mean frontal QRS axis. Chest roentgenography disclosed dextrocardia in 7 and levocardia in 11. Of 12 infants presenting with a marked decrease in pulmonary flow, 10 presented as ill neonates with hypoxia and acidosis. Four infants with increased pulmonary flow presented before 8 weeks with heart failure and mild cyanosis. Two with moderate pulmonary stenosis had mild cyanosis, but were asymptomatic. All had associated cardiac anomalies, pulmonary stenosis and persistent ductus arteriosus being the most common. For accurate diagnosis, angiographic demonstration of a posterior rudimentary chamber in addition to the main chamber of right ventricular trabecular pattern is mandatory.