Right Atrioventricular Valve Leaflet Morphology Redefined Implications for Transcatheter Repair Procedures

OBJECTIVES The authors aimed to comprehensively detail the right atrioventricular valve functional leaflet anatomies. BACKGROUND The rapid development of both surgical and percutaneous repair techniques for tricuspid regurgitation has renewed interest in variations in the morphology of the right atrioventricular valve. METHODS The functioning right atrioventricular valves of 40 reanimated human hearts were imaged using Visible Heart methodologies. Hearts were then perfusion-fixed and dissected, uniquely allowing for the comparative assessments of functional versus fixed valve anatomies from the same set of donor hearts. RESULTS The right atrioventricular valves have "3-leaflet" configurations in 57.5% and "4-leaflet" configurations in the remaining hearts. For 4-leaflet valves, extra leaflets were commonly observed in the most inferior regions of the annuli. No difference in valve perimeters between 2 valve types were observed (112.2 vs. 117.1 mm; p = 0.14). In 3-leaflet valves, septal, mural, and superior leaflets occupied 32.2 +/- 6.5%, 15.9 +/- 5.5%, and 25.5 +/- 6.2% of the annulus, respectively, whereas in the 4-leaflet arrangements, these values were 27.0 +/- 5.8% (septal), 12.0 +/- 4.5% (inferior), 13.7 +/- 9.4% (mural), and 19.8 +/- 6.1% (superior). The muroseptal/inferoseptal commissures were usually located in the cavotricuspid regions, whereas the inferomural and superomural commissures were in the right atrial appendage vestibule area. CONCLUSIONS The right atrioventricular valve has 4 functional leaflets in more than 40% of cases. The authors found that the inferomural region is the most variable area of the valve and believe that anatomic variation is an important consideration for planned interventions. (c) 2019 by the American College of Cardiology Foundation.