| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
|
|
|
|||||||
|
|||||||||
Ann Thorac Surg 2004;78:2063-2068
© 2004 The Society of Thoracic Surgeons
a Department of Thoracic and Cardiovascular Surgery
b Department of Cardiovascular Medicine
c Department of Biostatistics and Epidemiology, The Cleveland Clinic Foundation, Cleveland, Ohio, USA
Accepted for publication June 2, 2004.
* Address reprint requests to Dr Gillinov, Department of Thoracic and Cardiovascular Surgery, The Cleveland Clinic Foundation/F24, 9500 Euclid Ave, Cleveland, OH 44195 (E-mail: gillinom{at}ccf.org).
 |
Abstract |
|---|
 Top Abstract IntroductionPatients and MethodsResultsCommentAppendix The Computer ProgramReferences |
|---|
METHODS: We developed a computer program to reconstruct the mitral annulus based on spatial coordinates from three-dimensional echocardiography. Data were obtained at end-diastole and end-systole in 7 patients with ischemic mitral regurgitation and 5 normal control subjects. Mitral annular motion was quantified by calculating the displacement area of the annulus between end-diastole and end-systole.
RESULTS: Comparison of ischemic mitral regurgitation and control patients revealed differences in annular geometry and motion at end-diastole. Annular perimeter was greater in ischemic mitral regurgitation patients (10.7 ± 0.7 cm versus 8.6 ± 0.2 cm in control group; p < 0.03), with increased intertrigonal distance in ischemic mitral regurgitation patients (2.8 ± 0.3 cm versus 2.1 ± 0.1 cm; p < 0.06). These changes resulted in increased annular orifice area in ischemic mitral regurgitation patients (9.1 ± 1.2 cm2 versus 5.7 ± 0.3 cm2; p < 0.03). Ischemic mitral regurgitation patients had altered annular motion, with reduced movement of the posterior annulus (5.4 ± 0.7 cm2 versus 8.7 ± 1.1 cm2; p < 0.03).
CONCLUSIONS: Computer analysis of data obtained from three-dimensional echocardiography demonstrates altered annular geometry and motion in patients with ischemic mitral regurgitation. Patients with ischemic mitral regurgitation have annular dilatation, with an increase in anterior and posterior annular perimeters; this is accompanied by an increase in the intertrigonal distance and restriction of annular motion.
|
Introduction |
|---|
|
TopAbstractIntroductionPatients and MethodsResultsCommentAppendix The Computer ProgramReferences |
|---|
Three-dimensional (3D) echocardiography represents an important advance in the study of mitral valve function [1, 2]. We developed a computer program that uses data from 3D echocardiography to quantify mitral annular geometry and motion. The software calculates mitral annular perimeter, computes the 3D orifice surface area enclosed by the annulus, generates an animation of the mitral annulus, and quantifies the motion of the annulus during the cardiac cycle. Coupled with 3D echocardiography, this computer program was used to quantify perturbations in mitral annular geometry and motion in patients with IMR.
|
Patients and Methods |
|---|
|
TopAbstractIntroductionPatients and MethodsResultsCommentAppendix The Computer ProgramReferences |
|---|
|
Measurements from 3D echocardiography were performed at end-diastole and end-systole. Eighteen points were identified along the mitral annulus by 3D echocardiography (Fig 1A). Manual identification of points required approximately 1 hour for each study. A fast-Fourier transform digital filter was used to generate a smooth reconstruction of the annulus (Fig 1B) [3]. The computer program was written using the LabView Software (National Instruments, Austin, TX). All measurements of lengths and areas were done using 3D coordinate information with vector geometry. Spatial coordinates obtained by 3D echocardiography were provided as inputs to the computer program for offline analysis. Details of the computer program are included in the Appendix.
|
Geometric measurements in 3D space included anterior, posterior, and total annular perimeters; intertrigonal distance; and anterior, posterior, and total annular areas. Annular perimeter was defined as length from posterior trigone to posterior trigone. Anterior annular perimeter was defined as length from posterior to anterior trigone in continuity with the aortic valve (shorter segment). Posterior annular perimeter was defined as length from anterior to posterior trigone in the opposite direction (longer segment). Intertrigonal distance was defined as the straight-line distance from posterior to anterior trigone. Annular area was defined as the entire surface area bounded by the annulus, calculated using numerical integration (Fig 2). Anterior and posterior annular areas were defined as the areas of those portions of the annulus anterior and posterior to a line joining the trigones, respectively.
|
|
|
|
Results |
|---|
|
TopAbstractIntroductionPatients and MethodsResultsCommentAppendix The Computer ProgramReferences |
|---|
|
|
|
|
Comment |
|---|
|
TopAbstractIntroductionPatients and MethodsResultsCommentAppendix The Computer ProgramReferences |
|---|
Annular Geometry
Annular dilatation has long been recognized as a pathologic change associated with mitral regurgitation [8]. Carpentier [8] established the idea that dilatation affects the "mural leaflet and the commissural areas" and does not affect "the attachment of the aortic leaflet." The classic notion that the anterior annulus does not dilate requires reassessment [3–5]. Our measurements, performed in humans in vivo, indicate that both anterior and posterior portions of the annulus dilate proportionately in patients with IMR, although the magnitude of dilation of the posterior annulus is greater. Similarly the intertrigonal distance is increased in IMR at end-diastole. This suggests that all segments of the mitral annulus dilate in IMR.
Recent pathologic and experimental studies support these findings. Studying cadaveric human hearts in diastole, Hueb and coworkers [5] observed a 17% increase in annular perimeter in patients with ischemic cardiomyopathy; there was an accompanying 33% increase in the intertrigonal distance and a 26% increase in annular area. These results are similar to ours, with differences likely a result of experimental design (ex vivo versus in vivo) and measurement methodology (measurement from digital photographs versus computer analysis of data from 3D echocardiography).
Two groups have reported related changes in annular geometry in sheep models of chronic IMR [3, 4]. Building on their prior extensive experience, researchers at the University of Pennsylvania studied sheep before and after creating IMR [3]. Using sonomicrometry array localization, they found that IMR was associated with a 28% increase in annular perimeter, with this change being distributed proportionately between the anterior and posterior annulus. They also noted a 69% increase in annular area, similar to our value of 60%.
Working with a similar model of ovine IMR, Tibayan and associates [4] demonstrated both lengthening of the fibrous (anterior) annulus (14% to 15%) and of the muscular (posterior) annulus (18% to 22%); these changes produced a 48% increase in annular area. Like the group from the University of Pennsylvania, these investigators also documented the continuous change of these and other variables during the cardiac cycle, noting important changes in 3D annular shape as well as annular dimensions.
The data presented here complement our previous report detailing geometric changes in the mitral annulus in patients with IMR [1]. In that study, which included more than twice as many patients, we demonstrated an increase in the distance between the commissures in patients with IMR. In the current study we used different software to track the trigones rather than the commissures, and we measured distances at end-systole rather than mid-systole. Thus, the results of these two studies are not strictly comparable, although they provide complementary information concerning different components of the mitral annulus at different times of the cardiac cycle. Advances in image acquisition and computer analysis are necessary to enable quantification of annular geometry and motion during the entire cardiac cycle.
Annular Motion
The mitral annulus is a nonplanar 3D structure that moves in space during the cardiac cycle [1–4]. Although not as precise as sonomicrometry crystals or surgically placed arrays of markers used for experimental studies, 3D echocardiography can be used to study this motion in humans [1, 2]. In patients with IMR, annular motion is restricted, with the greatest change in motion occurring along the posterior annulus. Clinically, this is in concordance with echocardiographic findings of restricted posterior leaflet movement in IMR.
Several groups have studied other aspects of annular motion in models of IMR. Gorman and colleagues [3] observed changes in the distance from the papillary muscles to the annulus during the cardiac cycle in their ovine model. Tibayan and colleagues [4] used radiopaque markers to demonstrate changes in the saddle horn height during the cardiac cycle in a similar ovine model. This information is complementary to our observations in humans and serves to demonstrate the complexity of the changes in mitral annular motion associated with IMR.
Limitations and Complexity of Ischemic Mitral Regurgitation
This human study examined only 7 patients with IMR. The limitations of 3D echocardiography and the software enabled us to examine indices of mitral annular geometry and motion at only selected times, end-diastole and end-systole. The data presented do not quantify annular geometry and motion during the entire cardiac cycle. However, rapid advances in technology and software may soon enable real-time quantification of mitral annular geometry and motion continuously during the cardiac cycle. The limited data that we gathered demonstrated that perturbations of mitral annular geometry and motion were most pronounced at end-diastole, whereas differences observed at end-systole may be related to chance. It is possible that ventricular and annular contraction reduce end-systolic differences in annular geometry and motion between patients with IMR and normal individuals. Examination of larger numbers of patients at more points during the cardiac cycle is required to assess the impact of systolic contraction on annular size and function.
The computer software was not designed to assess changes in the geometry or motion of the mitral leaflets, left ventricle, or subvalvular apparatus. Changes in the geometry and motion of these structures contribute to the development of IMR [1–4]. Because of the multiplicity of factors involved in the pathogenesis of IMR, it is necessary to use data from multiple studies to characterize this complex phenomenon. Better understanding of IMR is necessary to enable a more focused study of the impact of surgical repair on IMR.
Clinical Inferences
The anterior mitral annulus dilates in patients with IMR; therefore, its length should not be used to judge annuloplasty size. Surgical repair by annuloplasty effectively reduces the septal-lateral diameter of the mitral annulus [7]. Detailed clinical study of the impact of different annuloplasty techniques on other indices of mitral annular geometry and motion is warranted.
|
Appendix The Computer Program |
|---|
|
TopAbstractIntroductionPatients and MethodsResultsCommentAppendix The Computer ProgramReferences |
|---|
Distance Between Two Points A, B
A is given by the coordinates (Ax, Ay, Az)
B is given by the coordinates (Bx, By, Bz)
Distance = 
[(Ax – Bx)2 + (Ay – By)2 + (Az – Bz)2].
Calculation of the Mitral Annular Perimeter
The reconstructed mitral annulus is composed of multiple points. The perimeter is defined by connecting adjacent points. If we start at point A0 at the anterior trigone and calculate the distance between adjacent points (segment lengths) and return to the starting location A0, then the sum of these segmental lengths is the perimeter of the annulus: thus, if A0, A1, A2, , An is the series of points defining the mitral annulus, and the distances between (A0, A1), (A1, A2), (A2, A3), , (An–1, An), are the segmental distances between adjacent points; the sum of these segments is the mitral annular perimeter.
If we are interested in calculating a partial length such as the anterior annulus, then the calculation of the distances is taken to that point. For example, if A0 defines the anterior trigone and Af defines the posterior trigone, then the sum of the distances in the series of points from A0 to Af will be the anterior annular perimeter.
Clearly, it is important to keep track of orientation on the annulus. If we travel in one direction from the anterior trigone, we will trace out the anterior annulus. From the same starting point on the anterior trigone, traveling in the opposite direction will trace out the posterior annulus.
Calculation of the Orifice Area in Three Dimensions
The mitral annulus is a 3D structure. To calculate the area of the surface bounded by the annulus, one can make the visual analogy of dipping a closed and bent wire frame into a soap solution. Figure 2A demonstrates this principle. The orifice area can be calculated by calculating the area of each four-sided polygon (quadrilateral). The sum of the areas of the quadrilaterals will be the orifice area.
Each quadrilateral can be broken down into two triangles. Therefore, the area of each quadrilateral is the sum of the two triangles. The area of the triangle can be calculated using Heron's formula:
Area of triangle = [s(s – a)(s – b)(s – c)],
where a, b, and c are the lengths of the three sides of the triangle and s is the semiperimeter of the triangle defined by (a + b + c)/2.
Calculation of the Motion Area
The motion area allows quantification of the degree of movement of the annulus during the cardiac cycle.
Let A0, A1, A2, , An be the set of points that define the annulus at end-diastole.
Let B0, B1, B2, , Bn be the set of points that define the annulus at end systole.
Then the motion area of the segment (A0, A1) can be calculated by calculating the area of the quadrilateral defined by the points (A0, A1, B0, B1). It is important to select a starting point that defines a key landmark such as the anterior or posterior trigone. The sum of the areas defined by these quadrilaterals between end-diastole and end-systole generates the motion area.
|
References |
|---|
|
TopAbstractIntroductionPatients and MethodsResultsCommentAppendix The Computer ProgramReferences |
|---|
Related Article
This article has been cited by other articles:
|
|
 |
|
  P. Tozzi, D. Locca, F. Gronchi, D. Hayoz, E. Ferrari, L. K. von Segesser, and R. Hullin Active mitral ring for post-surgical remote correction of residual mitral regurgitation on the beating heart Eur J Cardiothorac Surg, February 5, 2013; (2013) ezs710v1. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 K. R. Khabbaz, F. Mahmood, O. Shakil, H. J. Warraich, J. H. Gorman III, R. C. Gorman, R. Matyal, P. Panzica, and P. E. Hess Dynamic 3-Dimensional Echocardiographic Assessment of Mitral Annular Geometry in Patients With Functional Mitral Regurgitation Ann. Thorac. Surg., January 1, 2013; 95(1): 105 - 110. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 E. G. Caiani, L. Fusini, F. Veronesi, G. Tamborini, F. Maffessanti, P. Gripari, C. Corsi, M. Naliato, M. Zanobini, F. Alamanni, et al. Quantification of mitral annulus dynamic morphology in patients with mitral valve prolapse undergoing repair and annuloplasty during a 6-month follow-up Eur Heart J Cardiovasc Imaging, May 1, 2011; 12(5): 375 - 383. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
M. Shanks, V. Delgado, A. C. T. Ng, F. van der Kley, J. D. Schuijf, E. Boersma, N. R. L. van de Veire, G. Nucifora, M. Bertini, A. de Roos, et al. Mitral Valve Morphology Assessment: Three-Dimensional Transesophageal Echocardiography Versus Computed Tomography Ann. Thorac. Surg., December 1, 2010; 90(6): 1922 - 1929. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
M. Padala, R. A. Hutchison, L. R. Croft, J. H. Jimenez, R. C. Gorman, J. H. Gorman III, M. S. Sacks, and A. P. Yoganathan Saddle Shape of the Mitral Annulus Reduces Systolic Strains on the P2 Segment of the Posterior Mitral Leaflet Ann. Thorac. Surg., November 1, 2009; 88(5): 1499 - 1504. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 A. Itoh, D. B. Ennis, W. Bothe, J. C. Swanson, G. Krishnamurthy, T. C. Nguyen, N. B. Ingels Jr., and D. C. Miller Mitral annular hinge motion contribution to changes in mitral septal-lateral dimension and annular area J. Thorac. Cardiovasc. Surg., November 1, 2009; 138(5): 1090 - 1099. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 V. Mor-Avi, L. Sugeng, and R. M. Lang Real-Time 3-Dimensional Echocardiography: An Integral Component of the Routine Echocardiographic Examination in Adult Patients? Circulation, January 20, 2009; 119(2): 314 - 329. [Full Text] [PDF]
|
|
|
|
|
|
P. Ferrazzi, A. Iacovoni, S. Pentiricci, M. Senni, M. Iascone, N. Borenstein, L. Behr, A. Borghi, R. Balossino, and E. Quaini Toward the development of a fully elastic mitral ring: preliminary, acute, in vivo evaluation of physiomechanical behavior. J. Thorac. Cardiovasc. Surg., January 1, 2009; 137(1): 174 - 179. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 F. Veronesi, C. Corsi, L. Sugeng, V. Mor-Avi, E. G. Caiani, L. Weinert, C. Lamberti, and R. M. Lang A Study of Functional Anatomy of Aortic-Mitral Valve Coupling Using 3D Matrix Transesophageal Echocardiography Circ Cardiovasc Imaging, January 1, 2009; 2(1): 24 - 31. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 J-M Song, M-J Kim, Y-J Kim, S-H Kang, J-J Kim, D-H Kang, and J-K Song Three-dimensional characteristics of functional mitral regurgitation in patients with severe left ventricular dysfunction: a real-time three-dimensional colour Doppler echocardiography study Heart, May 1, 2008; 94(5): 590 - 596. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
E. Agricola, M. Oppizzi, M. Pisani, A. Meris, F. Maisano, and A. Margonato Ischemic mitral regurgitation: mechanisms and echocardiographic classification Eur Heart J Cardiovasc Imaging, March 1, 2008; 9(2): 207 - 221. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
P. W.M. Fedak, P. M. McCarthy, and R. O. Bonow Evolving Concepts and Technologies in Mitral Valve Repair Circulation, February 19, 2008; 117(7): 963 - 974. [Full Text] [PDF]
|
|
|
|
 |
|
 J. I. Fann, N. B. Ingels Jr., and D. C. Miller Pathophysiology of Mitral Valve Disease , January 1, 2008; 3(2008): 973 - 1012. [Full Text]
|
|
|
|
|
|
J. Kwan, G.-C. Kim, M.-J. Jeon, D.-H. Kim, T. Shiota, J. D. Thomas, K.-S. Park, and W.-H. Lee 3D geometry of a normal tricuspid annulus during systole: A comparison study with the mitral annulus using real-time 3D echocardiography Eur Heart J Cardiovasc Imaging, October 1, 2007; 8(5): 375 - 383. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
L. P. Ryan, B. M. Jackson, Y. Enomoto, L. Parish, T. J. Plappert, M. G. St. John-Sutton, R. C. Gorman, and J. H. Gorman III Description of regional mitral annular nonplanarity in healthy human subjects: A novel methodology J. Thorac. Cardiovasc. Surg., September 1, 2007; 134(3): 644 - 648. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
G. De Cicco, C. Russo, A. Moreo, C. Beghi, C. Fucci, P. Gerometta, and R. Lorusso Mitral valve periprosthetic leakage: anatomical observations in 135 patients from a multicentre study Eur J Cardiothorac Surg, December 1, 2006; 30(6): 887 - 891. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
Pitfalls and limitations in measuring and interpreting the outcomes of mitral valve repair. J. Thorac. Cardiovasc. Surg., March 1, 2006; 131(3): 523 - 529.
|
|
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
| ANN THORAC SURG | ASIAN CARDIOVASC THORAC ANN | EUR J CARDIOTHORAC SURG |
| J THORAC CARDIOVASC SURG | ICVTS | ALL CTSNet JOURNALS |
