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Updated: Jul 18, 2026
Biaxial Mechanical Characterizations of Atrioventricular Heart Valves
Published on: April 9, 2019
Morphologic features of the uniatrial but biventricular atrioventricular connection
Laszlo Kiraly1, Martha Hubay, Andrew C Cook
1Gottsegen Hungarian Institute of Cardiology, Pediatric Cardiac Centre, Budapest, Hungary. kiraly@kardio.hu
Insights
Hearts with absent atrioventricular connections and straddling atrioventricular valves present unique challenges for Fontan-like palliation. Valvar morphology is highly variable and prone to long-term insufficiency, impacting surgical outcomes.
Area of Science:
- Congenital heart disease
- Pediatric cardiology
- Cardiac surgery
Background:
- Absent atrioventricular (AV) connection with a straddling AV valve is a rare but significant congenital heart defect.
- These complex cardiac anomalies necessitate specialized surgical approaches, often involving Fontan-like palliation.
- The morphology of the atrioventricular valve significantly influences the success and long-term outcome of surgical interventions.
Purpose of the Study:
- To investigate the segmental arrangements and valvar morphology in hearts with absent AV connection and straddling AV valve.
- To clarify the specific anatomical features of these lesions and their implications for surgical management.
- To understand the relationship between valvar morphology and potential long-term complications.
Main Methods:
- Macroscopic review of cardiac specimens from three institutions.
- Inclusion criteria: absent AV connection with a straddling AV valve supported exclusively by a univentricular AV junction.
- Exclusion criteria: specimens with a common AV junction.
Main Results:
- Eleven hearts exhibited an absent right AV connection with a straddling left AV valve; three showed an absent left AV connection with a straddling right AV valve.
- Predominant features included right-hand ventricular topology and discordant ventriculoarterial connections.
- Consistent valvar abnormalities observed: dysplastic leaflets, short cords, abnormal attachments, and papillary muscles. A free-floating bridging anterosuperior leaflet and a bridging leaflet line of maximal coaptation perpendicular to the ventricular septum were noted.
Conclusions:
- Absent AV connection with a straddling AV valve results in a uniatrial but biventricular connection.
- The abnormal solitary AV valve cannot be definitively classified as mitral or tricuspid due to its unique morphology.
- The significant variability in valvar morphology suggests a high propensity for long-term valve insufficiency.
Objectives:
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.
Methods:
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.
Results:
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.
Conclusions:
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.
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