Absent Atrioventricular Connection Research Articles

Ventriculoatrial malalignment in atrioventricular septal defect resulting in uniatrial biventricular connection: surgical options

BackgroundUniatrial biventricular connection (UBC) is a rare cardiovascular anomaly characterized by absence of one atrioventricular connection and drainage of the other atrium via a solitary atrioventricular valve into both ventricles. The absent atrioventricular connection may affect either the left or right atrium. Because of the absence of one atrioventricular connection hearts with UBC have been classified among functionally univentricular hearts requiring palliative treatment according to the Fontan principle.Aims/objectiveWe report two further patients with UBC. In one of these patients careful echocardiographic examination of the atrioventricular junction in early infancy revealed the possibility of biventricular repair based on the favorable anatomy of the atrioventricular valve and balanced ventricles in the presence of an inlet ventricular septal defect (VSD).Case presentationsBoth patients presented in the neonatal period for evaluation of complex congenital heart disease. The anatomy of the atrioventricular valves in our patients was indistinguishable from atrioventricular septal defects exhibiting the morphology of a common valve with superior and inferior bridging leaflets. The common atrioventricular valve was connected exclusively to the right atrium draining into both ventricles while the left atrium drained into the right atrium via a secundum atrial septal defect. In one of our patients biventricular repair with good longterm-result was performed by reseptation of the atria, patch repair of the VSD and septation of the atrioventricular valve. The second patient underwent univentricular palliation according to the Fontan principle.Discussion/conclusionThe echocardiographic findings in our patients suggest that at least some patients with UBC represent a variant of atrioventricular septal defects associated with extreme ventriculoatrial malalignment resulting in fusion of the deviated primary atrial septum with the lateral aspect of the atrioventricular junction. This offers the option of septation of the common atrioventricular valve and biventricular repair in patients with adequate size of both ventricles. Exact echocardiographic analysis of the morphology of the atrioventricular valve is essential to distinguish these patients with a morphologically common atrioventricular valve in early infancy from other variants of absent atrioventricular connection and to select those who are suitable for biventricular repair.

The univentricular heart: Revisited

IntroductionA univentricular (UV) heart is found when both atria drain mainly into one ventricle; while if either ventricle cannot sustain the systemic or the pulmonary circulation, a functionally UV heart emerges. UV heart is the source of hot debates and discussions for decades that stem from controversies in terminologies, analysis, and management. ObjectiveTo study the morphological pattern of univentricular hearts. DesignCohort, descriptive study. SettingReview 13-year data from the file system of a high-volume, tertiary, teaching cardiac centre and study the patients having pathologies meeting the definition of UV heart. Results461 patients have UV hearts; constituting 1.4% of all patients with a congenital heart disease (CHD) visiting the centre of the study. Functionally UV heart in the form of biventricular atrioventricular (AV) connection plus one ventriculoarterial (VA) connection was seen in 179 cases (38%) with aortic atresia being the most common (N=98; 55%). On the other hand, UV AV connection was seen in 282 cases (62%). Under this category, 203 cases (72%) show an absent AV connection and 79 hearts (28%) with double-inlet anatomy. ConclusionUV heart is a rare complex CHD with lots of scientific debates. It is hoped that this long-term study will be the basis and a reference to paediatric cardiologists, echocardiographers, and other interested professionals.

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.

Survival and Prognostic Factors in Patients With an Absent Atrioventricular Connection

To identify anatomical and functional characteristics associated with survival in adult patients with an absent atrioventricular connection and to highlight the diagnostic importance of echocardiography. The clinical histories and echocardiographic and hemodynamic test results of 24 patients were recorded. Some 87.5% of patients were in New York Heart Association (NYHA) functional class I/II. In 92%, the ECG demonstrated sinus rhythm and left ventricular dilatation. Chest X-ray showed grade-II cardiomegaly in 83%. Situs solitus and an absent right atrioventricular connection were found on echocardiography in 92%. The ventriculoarterial connection was most frequently concordant (in 71%). All patients had an atrial septal defect, 21 had a ventricular septal defect and 21 had decreased pulmonary flow. The ejection fraction of the main ventricle in the whole patient group was 55% +/- 10%; 52% +/- 12% in those who did not undergo surgery and 58% +/- 8% in those who did (P=NS). Factors associated with poor survival were an ostium secundum atrial septal defect, hemoglobin <16 g/dL and a main ventricle ejection fraction <50%. Of the 54% of patients who underwent surgery, 85% are alive and the majority are in NYHA functional class I/II. Among those who did not, 82% are alive and 73% are in NYHA functional class I/II. The presence of a wide atrial septal defect, a normal hemoglobin level and a normal main ventricle ejection fraction were associated with the survival of these patients into adulthood. Echocardiography can provide clinicians and surgeons with information that is valuable for selecting treatment and monitoring follow-up.

Morphologic features of the uniatrial but biventricular atrioventricular connection

Hearts with an absent atrioventricular connection and a straddling of the solitary atrioventricular valve are rare but significant lesions. They are suitable only for Fontan-like palliation, in which atrioventricular valvar abnormalities play a significant role in determining the outcome. We studied the segmental arrangements in such lesions and clarified the valvar morphology, particularly its surgical implications. We made a macroscopic review of all specimens with an absent atrioventricular connection and a straddling atrioventricular valve that were held in the collections of 3 institutes. We included only those specimens with the straddling valve supported exclusively by either the right-sided or left-sided atrioventricular junction and excluded those with a common atrioventricular junction. We found 11 hearts with an absent right atrioventricular connection and a straddling left atrioventricular valve, and 3 with an absent left atrioventricular connection and a straddling right atrioventricular valve. Most had right-hand ventricular topology and discordant ventriculoarterial connections. We found multiple valvar abnormalities, including dysplastic leaflets, short cords, abnormal attachments, and abnormal papillary muscles. The most consistent features were a line of maximal coaptation between the bridging leaflets always perpendicular to the plane of the ventricular septum and a free-floating bridging anterosuperior leaflet. Straddling of a solitary atrioventricular valve with an absent atrioventricular connection produces a uniatrial but biventricular connection. In this setting, the valve guarding the abnormal solitary atrioventricular junction cannot be classified morphologically as mitral or tricuspid. The markedly variable valvar morphology likely makes these valves prone to insufficiency in the long term.

Comparative value of transthoracic and transesophageal echocardiography in the assessment of congenital abnormalities of the atrioventricular junction

Information obtained from transthoracic and transesophageal echocardiography (two-dimensional echocardiography with spectral Doppler and color How imaging) was compared in 17 patients with major congenital ibnormalities of the atrioventricular (AV) junction (10 discordant AV connections, 1 criss-cross connection, 5 absent right connections and 1 absent left connection). The findings by either technique were correlated with findings at cardiac catheterization (12 patients) and at surgery (5 patients).In two of six patients with an absent AV connection as defined by transthoracic echocardiography, transesophageal imaging demonstrated an imperforate AV valve. In 11 of 11 patients with a discordant or criss-cross connection, assessment of AV valve and ventricular morphology (by defining the chordal attachments of both AV valves) was possible with transesophageal echocardiography (3 of 11 patients by transthoracic echocardiography); chordal straddling was detected in 1 patient and excluded in 3 others with an associated inlet ventricular septal defect. Anomalous pulmonary venous connection (one patient), atrial septal defect (three patients) and subpulmonary stenosis (five patients) were better assessed by transesophageal imaging, and atrial appendage morphology could be demonstrated in all.The transesophageal technique was less useful in demonstrating the anterior subaortic infundibulum or aortopulmonary shunt (two patients). Although systemic ventricular function could be assessed by either method with use of short-axis M-mode scans, transasophagerel pulsed Doppler interrogation of AV valve and pulmonary venous flow patterns provided clues to diastolic dysfunction of the systemic ventricle.

EVALUATION OF UNIVENTRICULAR ATRIOVENTRICULAR CONNECTION BY NMR IMAGING

Twelve patients (pts), ages 7 mos. to 23 yrs. (mean 11 yrs.), with known univentricular atrioventricular (AV) connection (“Single ventricle”) were evaluated by ECG-gated magnetic resonance imaging (MRI). Multiple sections were obtained in transverse, coronal and oblique planes using a 0.3T or LOT magnet and SE 30 pulsing techniques. MRI studies were evaluated using a segmental approach prior to reviewing the echocardiograms and angiograms which were available on all pts. MRI accurately depicted: 1) cardiovisceral and atrial situs 2) presence of splenic tissue 3) systemic and pulmonary venous connections 4) the mode of AV connection (i.e. absent right, double inlet, etc.) 5) the morphology and spatial relationships of the main and rudimentary ventricular chambers (6) the ventriculoarterial (VA) connections and 7) surgical procedures (i.e. shunts, PA bands). Seven pts had absent right AV connection, 4 had double inlet anatomy and 1 had an absent left AV connection. The absent AV connection was true atresia in 6 with invagination to the cardiac crux of fat-containing sulcus tissue which appears bright on MRI and an imperforate valve in 1. In 11 pts, the rudimentary chamber could be visualized. VA discordance was demonstrated in 2 pts with absent right AV connection, in all 5 with double inlet LV's and the 1 with absent left AV connection. We conclude that MRI accurately depicts cardiac morphology in pts with univentricular AV connection, often providing information not available with other imaging techniques.

Mitral atresia. Morphological details.

The morphological characteristics of mitral atresia were studied in 30 hearts to determine the presence or absence of a morphological rudiment of the atretic valve and the relation of this rudiment, if found, to any chamber in the ventricular mass. All the hearts showed atrial situs solitus and no ventricular inversion; consequently all had left atrioventricular atresia. In all instances dense fibrous tissue connected the floor of the left atrium to the left ventricle. This connective tissue is considered to be the morphological rudiment of the atretic mitral valve. In several hearts the intervening fibrous tissue varied from a thick fibrous membrane to a tiny fibrous cord; it is impossible to detect these variations clinically. It is, therefore, more practical to classify those hearts which have a detectable fibrous membrane macroscopically as having an "imperforate membrane" and those with a fibrous strand detectable only microscopically as having an "absent atrioventricular connection."

Anatomy of the echocardiographic crux cordis in the evaluation of the spectrum of atrioventricular valve atresia

The echocardiographic crux cordis is defined in normal subjects as the spatial interrelation between the atrial and ventricular septal planes and the plane of the atrioventricular (AV) junction. This crossroad can be visualized using apical, subcostal, or precordial four-chamber echocardiographic projections. We studied this relationship in 33 patients with right AV valve atresia (29 with absent AV connection, 4 with an imperforate AV valve) and 14 with left AV valve atresia (9 with absent AV connection, 5 with an imperforate valve). An accurate diagnosis of AV valve atresia was successfully achieved in all patients, while the differentiation between an imperforate AV valve and absence of an AV connection was achieved in 45 out of 47 cases. Echocardiography demonstrated in some cases of absent AV connection, an arrangement which at first sight was analogous to that found in hearts with AV concordance and an imperforate AV valve. The differential diagnosis, therefore, must be based on the differing echocardiographic characteristics of the atretic atrial floor. In 31 out of 38 cases with absent AV connection it was possible to obtain simultaneous visualization of the ventricular septum and the atretic atrial floor. This proved helpful in planning the clinical management of these patients. The evaluation of crux cordis anatomy also differentiated AV valve atresia from other cardiac malformations with a similar presentation (valvular hypoplasia and common AV valve). It may prove the most reliable tool for the differential diagnosis of the spectrum of AV valve atresia.

Straddling atrioventricular valve with absent atrioventricular connection. Report of 10 cases.

Straddling atrioventricular valve with absent atrioventricular connection. Report of 10 cases.

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.

Two dimensional echocardiographic categorisation of the univentricular heart. Ventricular morphology, type, and mode of atrioventricular connection.

Most univentricular hearts have two chambers in their ventricular mass, only one of which possesses an atrioventricular connection. Categorisation into univentricular heart of right, left, or indeterminate type, using two dimensional echocardiography has been successfully achieved in 122 out of 132 patients to whom this technique has been applied. Thus, right ventricular rudimentary chambers in 84 univentricular hearts of left ventricular type were shown to be anterosuperior and either to the right or left. In contrast, left ventricular rudimentary chambers in 25 univentricular hearts of right ventricular type were posteroinferior and to the right, left, or directly posterior. Thirteen univentricular hearts of indeterminate morphology were characterised by absence of rudimentary chamber on angiography and echocardiography. The trabecular pattern of both main and rudimentary chambers were separately identified in some of the patients with univentricular hearts of right and left ventricular type and two dimensional echocardiography also illustrated the mode of atrioventricular connection, either via two atrioventricular valves, a common valve, or a valve straddling or overriding the trabecular septum. Finally it was also possible to distinguish absent atrioventricular connection from an imperforate valve in 10 patients.