J Thorac Cardiovasc Surg 2005;130:1480-1481
© 2005 The American Association for Thoracic Surgery
Whatever the approach, cutting strut chordae would not smell as sweet
Mathias H. Aazami, MD,
Mehrdad Salehi, MD,
Roya Satarzadeh, MD
Department of Cardiac Surgery and Thoracic Transplantation, Tehran University of Medical Sciences, Tehran, Iran
To the Editor:
With the first clinical application of Messas and colleagues' ovine trial,
1
Fayad and colleagues
2
reported the case of a patient with chronic ischemic mitral regurgitation (CIMR) who was managed successfully with strut chordae severing through an exclusive aortotomy and concomitant coronary artery bypass grafting. Although encouraging midterm results were reported, the objection can be raised to the authors' rationale of a "cut-and-go" approach in the face of such a complex pathophysiologic entity. As indicated by the authors, the factors involved in the genesis of CIMR are multiple and intricate, reflecting the complexity in preoperative analysis of CIMR mechanisms attempted at surgical planning. Similarly, it is our belief that factors involved in the postoperative regression of moderate CIMR are too complex to be ascribed to a given procedure, especially when taking into account reverse ventricular remodeling after coronary artery bypass grafting and possible improvement in intramyocardial conduction, 2 factors that are not taken into account in experimental models of CIMR.
The direct access offered by exclusive aortotomy to approach strut chordae is appealing, but that is at the loss of perioperative analysis of mitral apparatus, still of paramount importance in surgical decision-making. In our experience, the superior left atrial approach offers an adequate surgical field, even in the setting of CIMR or rheumatic disease, and for preprocedural and postprocedural functional analyses of mitral apparatus. Other advantages of a superior left atrial approach include a lesser distortion of mitral annulus and likelihood of perioperative or postoperative bleeding compared with an interatrial approach or aortotomy, respectively.
The authors' technique is conceived according to the conclusions of an experimental study reported by Messas and colleagues.
1
Yet from a pathophysiologic perspective, the conclusions provided by this study remain open to criticism. Moreover, this study is based on Kunzelman and Cochran's
3
in vitro study of mechanical characteristics between primary and secondary chordae, which found a greater amount of stress borne by primary chordae than by secondary chordae. Thus, Kunzelman and Cochran's statements were challenged by the in vivo investigation of Lomholt and colleagues,
4
which demonstrated that secondary chordae are more important mediators of the valvular–ventricular interaction than primary chordae, and that cutting secondary chordae adversely impairs left ventricular systolic pump performance.
Finally, we would stress that each strut chorda belongs to a given functional unit (Figure 1), anterior or posterior papillary muscle complexes (PMCs). Thus, it is mandatory to determine which PMC is involved predominantly in the tenting process, or in other words, the culprit strut chorda should be individualized. In our opinion, the management of mechanical imbalance between 2 PMCs resulting in leaflet tethering should be assumed by a selective restoration of the geometric relationships of the culprit PMC according to the annular plan
5
rather than by suppressing the principal mediators of valvular–ventricular continuity.
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Figure 1. Secondary chordae seen through aortotomy. The functional division line of anterior leaflet according to papillary muscle complexes (PMCs) (dotted arrow). Each half is supported by a strut chorda. Strut chordae belonging to APM and PPM. APM, Anterior papillary muscle; PPM, posterior papillary muscle.
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References
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- Messas E, Pouzet B, Touchot B, Guerrero JL, Vlahakes GJ, Desnos M, et al. Efficacy of chordal cutting to relieve chronic persistent ischemic mitral regurgitation. Circulation 2003;108(Suppl 1):II111-II115.[Medline]
- Fayad G, Modine T, Le Tourneau T, Al-Ruzzeh S, Ennezat PV, Decone C, et al. Chordal cutting technique through aortotomy. a new approach to treat chronic ischemic mitral regurgitation. J Thorac Cardiovasc Surg 2005;129:1173-1174.[Free Full Text]
- Kunzelman KS, Cochran RP. Mechanical properties of basal and marginal mitral valve chordae tendineae. ASAIO Trans 1990;36:M405-M408.[Medline]
- Lomholt M, Nielsen SL, Hansen SB, Andersen NT, Hasenkam JM. Differential tension between secondary and primary mitral chordae in an acute in-vivo porcine model. J Heart Valve Dis 2002;11:337-345.[Medline]
- Kron IL, Green GR, Cope JT. Surgical relocation of the posterior papillary muscle in chronic ischemic mitral regurgitation. Ann Thorac Surg 2002;74:600-601.[Abstract/Free Full Text]
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