AN IN-VITRO STUDY OF THE CORRELATION BETWEEN AORTIC-VALVE DIAMETER AND MITRAL INTERTRIGONAL DISTANCE - A SIMPLE METHOD TO SELECT THE CORRECT MITRAL ANNULOPLASTY RING SIZE

Background and aims of the study: The application of the flexible Dura n mitral annuloplasty ring in the treatment of various mitral valvular diseases is a physiologically appealing method of surgical repair. Ho wever, accurate identification of the trigonal structures, which is cr ucial in selecting the proper ring size, cannot always be made with ce rtainty. A method is proposed to calculate the intertrigonal distance (ITD) from the aortic diameter. Methods: Using digital calipers, the l inear intertrigonal distance was measured in human homograft (n = 10) and sheep (n = 10) aortic root specimens. The aortic diameter was obta ined from the circumference of the pressurized aortic root. A conversi on factor was acquired for each specimen by dividing the aortic diamet er with the measured ITD. A single constant conversion factor, which c losely approximated the mean of the conversion factors in both groups, was then applied broadly to derive the ITD by calculation from the ao rtic diameter, which is known. The validity of using this constant con version factor was tested by comparing the degree of variation of the calculated ITD from the direct measurements of the ITD. Results: The m ean of the conversion factors was 0.79 and 0.80 in the human and the s heep roots, respectively. The value 0.80 was used as the constant conv ersion factor in both groups for calculating the ITD. A paired compari son t-test in each group showed the difference between the calculated intertrigonal distance and the direct measurements of the ITD to be in significant, validating the use of 0.80 as a constant conversion facto r. Conclusions: The results of the study suggest that the conversion f actor of 0.80 can be reliably used to obtain a calculated value of the intertrigonal distance; this method has the potential to aid the surg eon in determining the intertrigonal distance and the proper ring size .