Reconstruction of the Left Atrioventricular Valve with Pericardial Patch Closure of the Ostium Primum Atrial Septal Defect in a Patient with Partial Atrioventricular Septal Defect under Mild Hypothermic Extracorporeal Circulation and Cardioplegic Arrest (UKC’s Modification): A Video Presentation

INTRODUCTION

The atrioventricular septal defect encompass a spectrum of lesions, in which the common etiology appears to be abnormal development of the superior and inferior endocardial cushions resulting in a deficiency or absence of the atrioventricular septum.^[1-6] This deficiency of the atrioventricular septum results in an ostium primum defect immediately above the atrioventricular valves and a scooped out area in the inlet (basal) portion of the ventricular septum.

Atrioventricular septal defects include a spectrum of malformations. At one end of the spectrum is the partial or incomplete atrioventricular septal defect characterized by an interatrial communication, but no interventricular communication, two separate valve orifices, and a connection of variable width between the left superior and left inferior leaflets. At the other end is the most extreme form with large deficiencies in the atrial and ventricular septa, and a common atrioventricular valvular orifice, known as complete atrioventricular septal defect.^[1-6]

Following Carpentier’s concepts on this malformation, the terms left atrioventricular valve and right atrioventricular valve are used instead of mitral valve and tricuspid valve, respectively.^[7] The term septal commissure is used instead of cleft to indicate the gap between the left superior and left inferior leaflets.^[3,7]

A fenestration or perforation of the left atrioventricular valve is an orifice, congenital or acquired in origin, well separated from the main orifice but not supported by a chordal apparatus. Accessory clefts or commissures, defined as radial openings from the free edge of a leaflet, is complete (up to the annulus) or incomplete (partially splitting the leaflet) [Video 1].^[3,6,7]

Anomalous positions of the papillary muscles are common in atrioventricular septal defect and are difficult to classify. Malformations of papillary muscles include abnormally thick muscles with rudimentary or absent chordal apparatus inserted directly into the under surface of the leaflets and multiple thin muscles with abnormal insertions into the ventricular walls.^[4,6,7]

Several anatomical features are shared among all types of atrioventricular septal defects.^[1-6] These include: (a) absence of the usual wedged position of the aortic valve due to a common atrioventricular valve ring; (b) lengthened outlet septum-to-ventricular apex ratio, resulting in an elongated left ventricular outflow tract and a “goose-neck” appearance; (c) inferior displacement of the atrioventricular node and coronary sinus; (d) shortened dimension of the inlet septumto-ventricular apex giving the interventricular septum a “scooped out” appearance; (e) apical displacement of the attachments of the atrioventricular valves to the ventricular crest; and (f) variable degrees of underdevelopment of the inlet septum, resulting in absence of a ventricular septal defect, a restrictive ventricular septal defect, or a large ventricular septal defect.^[1-7]

Abnormal differentiation and remodeling of the cushion mesenchyme into valvuloseptal tissue is the mechanism for development of atrioventricular septal defects.^[8] The wide variability in the degree of development of the endocardial cushions explains the variability in size and extent of the septal defects and varying grades of malformed atrioventricular valves.^[9]

Left atrioventricular valve regurgitation is graded as per the recommendation of the American Society of Echocardiographic criteria.^[10]

• 0→ None/trivial (<5% of left atrioventricular valve area)

• 1→ Mild (5−20% of left atrioventricular valve area)

• 2→ Moderate (20−40% left atrioventricular valve area)

• 3→ Severe (>40% left atrioventricular valve area).

Despite improved outcomes of partial atrioventricular septal defect repair overtime, several morphological and functional issues continue to be the causative factors for the post-operative left atrioventricular valve regurgitation, supraventricular arrhythmias, and late mortality and morbidity.^[11-17]

One of the keys to successful repair of atrioventricular septal defect by any technique is intraoperative assessment using transesophageal echocardiography and after cardiotomy.

We report here-in the surgical repair of the partial atrioventricular septal defect with a cleft left atrioventricular valve. A 26-year-old male patient diagnosed with partial type of atrioventricular septal defect in sinus rhythm, cleft left atrioventricular valve with mild pulmonary arterial hypertension, and severe left atrioventricular valvular regurgitation underwent successful reconstruction of the left atrioventricular valve and pericardial patch closure of the atrial septal defect.

SURGICAL TECHNIQUES

Intraoperative transesophageal echocardiography was performed using a Hewlett-Packard Sonos 5500 ultrasound system (Hewlett-Packard Co, Andover, MA) to assess the morphology of the values, intracardiac anatomy, degree of valvular regurgitation, and ventricular function.

SHORT- AND LONG-TERM RESULTS

The post-operative recovery was uneventful. At 8 months follow-up, the patient was asymptomatic, in sinus rhythm and no clinical evidence of cardiac failure with New York Heart Association Functional Class II. Echocardiography revealed normal biventricular function without atrioventricular valvular regurgitation. There were no residual atrial or ventricular septal defects.

CONCLUSION

Detailed assessment of the valve morphology by transesophageal echocardiography and intraoperative injection of cold saline with systematic individualized valvuloplasty techniques improves the outcome. In late presenters, the left atrioventricular valvular apparatus gets grossly deformed with dilated annulus and additional commissural leaks. Due to the morphological heterogeneity of the left atrioventricular valvular apparatus, left ventricular outflow tract, and displaced conduction system, an individualized management algorithm customized to each patient’s anatomy would be desirable.