Demonstrate role of inter-papillary distance (IPD) in MR from cardiomyopathy and its importance in ventricular geometry restoration. Inappropriate IPD alteration affects mitral apparatus dimensions - Apico-Papillo-Chordal length (APC), causing prolapse.
Twenty normal and twenty - 2, 3,and 4 fold papillary displacement myopathy porcine models created by author using serial dilation technique were studied before and after IPD obliteration. Complete papillary approximation suture encircled and transfixed mid portion of both papillary muscles. APC and Apico-Annular distance (AA) and height of leaflet free edge above annular plane (flail) were measured. Competence of valve was judged at 50, 80, 100 and 120mm Hg using a closed circulatory loop, static LV loading system.RESULTS: Normal hearts: IPD was 0.6mm(0.5-0.7), AA was 5.8mm(5.6-6.3). IPD obliterartion flailed both leaflets by 3–4 mm producing moderate and severe regurgitation at 80 and 120 mm. All changes reversed upon releasing suture and restoring IPD to normal.Myopathy models: IPD was 1.2, 1.8 and 2.4cms for 2, 3, and 4 fold myopathy models, AA was 6.6cms (6.2-7.1cms) with moderate MR from tethering in the 3 and 4 fold models only. IPD obliteration caused 4 – 5 mm flail in 2 fold myopathy, with moderate regurgitation at 80mm, but severe regurgitation at 120 mmHg. In 3 and 4 fold myopathy models, 6–8 mm flail with severe regurgitation noted from 50mmHg. Release of suture reversed regurgitation and flail in 2 fold myopathy while in 3 and 4 fold myopathy, flail reverted to tethering, with baseline MR. Degree of flail was related to degree of over-reduction of IPD.
Apex to annulus forms hypotenuse of triangle with apico-papillary and papillo-chordal portions as sides. Obliteration of IPD flattens the sides of this triangle and, since the sum of lengths of two sides exceeds that of hypotenuse, both leaflets flail.CLININCAL IMPLICATION: In LV geometry restoration and volume reduction surgery, reduction of IPD to less than normal results in functional regurgitation from flail.
V. Vijay, None.