CHAPTER 25 POSTERIOR LEAFLET CLOSED 25-1

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MITRAL VALVE MECHANICS by Neil B. Ingels, Jr. and Matts Karlsson

Figure 25.1 Marker location schematic. See Chapter 23 text for marker locations.

CHAPTER 25 POSTERIOR LEAFLET CLOSED

In Chapter 24 we noted that the posterior leaflet edge perimeter changes by a mean value of 32 mm throughout the cardiac cycle, while the mitral annular perimeter changes by 13 mm and the anterior leaflet perimeter by only 7 mm. This suggests the possibility that the posterior leaflet may play a disproportionate role in mitral valve opening and closing. In this chapter, we begin to explore this possibility.

Figure 25.1 repeats, for reference purposes, the marker locations shown and described in Chapter 23. Data and animations for this chapter are in Appendix E.

Figures 25.2, 25.3, and 25.4 show the leaflet, annular, and papillary geometry associated with the closed valves whose maximally open geometry was shown in Chapter 24, Figures 24.2, 24.3, and 24.4.

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Figure 25.3 Three dimensional view of the mitral complex during maximum posterior leaflet closing for COM06R01

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As can be seen in the upper right panels of each figure, clearly the posterior leaflet in the closed valve has not only considerably reduced the perimeter of its free edge from its open state, but this edge has now approximated some of the scalloped geometric features shown in Figure 23.2.

Figures 25.6, 25.6, and 25.7 show the nature of this transition in greater detail. The upper left panel in each of these figures displays left ventricular pressure (LVP, mmHg) and leaflet separation D0708 (SEPARATION, mm) during a multiple-beat sequence. The upper middle panel shows the corresponding annular perimeter (ANNULUS), posterior leaflet edge perimeter (POSTERIOR LEAFLET), and anterior leaflet edge perimeter (ANTERIOR LEAFLET), all in mm, for these beats. Note the much greater dimensional changes of the edge of the posterior leaflet relative to the edge of the anterior leaflet throughout the cardiac cycles. The remaining 9 panels show the distance (mm) between adjacent markers on the posterior leaflet edge during these beats, starting from the anterior commissure (D0102) and ending with the posterior commissure (D1413). While each heart exhibits its own pattern of

posterior leaflet edge segmental dynamics, in each heart, D0506 and D0911 exhibit consistently large excursions, suggesting that these regions contribute importantly to the opening and closing dynamics of the posterior leaflet in all three hearts. In the next chapter, we further explore the behavior of the posterior leaflet regions near these regions (i.e., near Markers #5, 6, 9, and 11).

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MITRAL VALVE MECHANICS by Neil B. Ingels, Jr. and Matts Karlsson Figure 25.6 Posterior leaflet edge segmental lengths for COM06R01. See text for details.