Chordal preservation during MVR (mitral valve replacement)

Chordal preservation during MVR (mitral valve replacement)

Abstract: Chordal preservation is important in maintaining LV function after surgery. Severe calcification and sub valvar fibrosis make chordal preservation during surgery difficult.

The concept of chordal preservation during mitral valve replacement was introduced by Lillehei CW and associates,¹ as early as 1964, to prevent the postoperative low output syndrome. Experimental evidence in support of chordal preservation was provided by canine studies of David TE and colleagues.² They demonstrated deterioration of left ventricular function in the absence of chordal preservation. Chordal preservation maintains the annular ventricular continuity and prevents progressive dilatation of the left ventricle which can occur in its absence.

Partial chordal preservation vs total chordal preservation

Many operators preserve the posterior leaflet and chordae while excising the anterior leaflet and chordae. This is because of the possibility of redundant anterior chordal tissue obstructing the left ventricular outflow tract. Preservation of both chordal systems may also necessitate downsizing of the mitral prosthesis. But a randomized trial of partial vs complete chordal preservation suggested that the results are better with complete than partial chordal preservation.³

Chowdhury UK et al have reported on chordal preservation in the setting rheumatic heart disease.⁴ Of their four hundred and fifty one patients, seventy had complete excision of the mitral sub valvular apparatus. One hundred and twenty four patients had preservation of the posterior chordal papillary structures while two hundred and fifty seven had total chordal papillary preservation. They demonstrated that left ventricular ejection fraction and fraction shortening declined over time in the group without chordal preservation. Total chordal preservation group fared better than the partial chordal preservation group and the group without chordal preservation.

Important factors to be considered while preserving the chordae are:

1. Prevention of left ventricular outflow tract obstruction due to systolic anterior motion of the preserved portion of the anterior mitral leaflet
2. Prevention of interference with prosthetic valve function
3. Ensuring an adequate sized prosthesis to prevent postoperative patient prosthesis mismatch

References

1. Lillehei CW, Levy MJ, Bonnabeau RC. Mitral valve replacement with preservation of papillary muscles and chordae tendinae. J Thorac Cardiovasc Surg 1964; 47: 532-43.
2. David TE, Straus HD, Mesher E, Anderson MJ, MacDonald IL, Buda AJ. Is it important to preserve the chordae tendinae and papillary muscles during mitral valve replacement? Can J Surg 1981; 24: 236-39.
3. Yun KL, Sintek CF, Miller DC, Schuyler GT, Fletcher AD, Pfeffer TA, Kochamba GS, Khonsari S, Zile MR. Randomized trial of partial versus complete chordal preservation methods of mitral valve replacement: A preliminary report. Circulation. 1999 Nov 9;100(19 Suppl):II90-4.
4. Chowdhury UK, Kumar AS, Airan B, Mittal D, Subramaniam KG, Prakash R, Seth S, Singh R, Venugopal P. Mitral valve replacement with and without chordal preservation in a rheumatic population: serial echocardiographic assessment of left ventricular size and function. Ann Thorac Surg. 2005 Jun;79(6):1926-33.