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© 2004 European Association of Cardio-Thoracic Surgery
Perioperative changes in dynamic aortic root morphology after Yacoub's root remodeling and concomitant aortic annuloplasty
a Department of Cardiovascular Surgery, Memorial Heart Center, Iwate Medical University, 1-2-1 Chuoudori Morioka City, Iwate, Japan
* Corresponding author. Tel.: +81-19-651-5111; fax: +81-19-624-8384 Received October 18, 2003; received in revised form March 4, 2004; accepted March 15, 2004
We have performed aortic root remodeling concomitant with aortic annuloplasty (subvalvular circular annuloplasty: it tightens the aortic annulus, using Gore-Tex strip (N.L. Gore and Associates, Arizona, USA)) in patients with AAE and AR. We examined morphologic changes in the aortic root during cardiac cycles, using pre- and post-operative echocardiography. Twelve patients were underwent the procedure. Their grade of AR was 3.2±1.0. Five adults with normal aortic roots were studied as controls. The systolic and diastolic radius of each cusp was measured at the annulus, the Valsalva and the STjunction level. The ratio of diastolic radius to systolic radius in the control, pre-operative data and post-operative data was obtained. In the controls, the rate of diameter change during the cardiac cycle was largest at the annulus level (Right coronary cusp (RCC), Left coronary cusp (RCC), Noncoronary cusp (NCC); 1.00±0.2, 1.12±0.1, 1.23±0.2), second largest at Valsalva level (RCC, LCC, NCC; 0.96±0.6, 1.07±0.2, 0.97±0.2), and smallest at the ST junction (RCC, LCC, NCC; 0.95±0.4, 1.03±0.2, 0.93±0.2). Pre-operative data showed that it was largest at the Valsalva level. Post-operative data showed that the rate of change at each level was not significantly different from the control data. All patients were in NYHA class I and the grade of AR was 0.4±0.7 at the latest follow-up. Subvalvular circular annuloplasty did not interfere with annulus motion during the cardiac cycle. Aortic root remodeling and concomitant aortic annuloplasty restored near normal cyclic aortic root motion and morphology on the short-term.
Key Words: Aortic root morphology; Aortic root motion; Aortic root remodeling; Subvalvular circular annuloplasty
Aortic root remodeling, a procedure that was introduced by Yacoub et al. [1,2], has been performed by many centers throughout the world. Some of these have reported recurrent aortic regurgitation (AR) after the operation. One of the causes of recurrence of AR is an unsecured aorto-ventricular junction. David et al. reported that reinforcement of the aorto-ventricular junction brought about reduced recurrence of AR [3,4]. We have performed aortic root remodeling concomitant with aortic annuloplasty (subvalvular circular annuloplasty) in patients with annuloaortic ectasia (AAE) and AR to treat AR and prevent aortic annulus from dilation in the future. We have achieved satisfactory results [5,6]. A number of clinical studies have demonstrated the effectiveness of Yacoub's procedure [7–9], but few papers have verified that the procedure preserves physiological motion and morphology of the aortic root [9]. This study reported that aortic root remodeling is superior to aortic root reimplantation in that the aortic root moves flexibly during cardiac cycle, rendering it more physiological and preserving normal cardiac function [9]. We added subvalvular circular annuloplasty [5] to aortic root remodeling. This may reduce AR, but the effect on aortic root motion during the cardiac cycle was obscure. Since the main method for evaluating the aortic root in other studies was transthoracic echocardiography (TTE), the cardiac motion information that has been obtained is two-dimensional. While it is very difficult to evaluate the whole morphology of the aortic root during the cardiac cycle, transesophageal echocardiography (TEE) can more precisely evaluate axial and longitudinal lengths of the aortic root and can reconstruct three-dimensional images more easily [10]. TEE can evaluate the aortic root more precisely, because subvalvular circular annuloplasty tightens the aortic annulus, which is three-dimentional rather than two-dimensional. The objectives of this study were: (1) to reconstruct the time-varying, three-dimensional shape of the aortic root during the cardiac cycle using TEE before and after aortic root remodeling; (2) to investigate the impact of subvalvular circular annuloplasty on the dynamic morphology during the cardiac cycle.
Twelve patients with AAE and AR underwent aortic root remodeling and aortic annuloplasty (subvalvular circular annuloplasty). There were 3 women and 9 men, with a mean age of 56.2±10.3 years. They had grade 1 to grade 4 aortic insufficiency. Two patients had grade 1 AR, 1 patient had grade 2 AR, 2 patients had grade 3 AR and 7 patients had grade 4 AR. Echocardiographic data are shown in Table 1. All aortic valves were tricuspid. Twelve patients were degenerative valve disease and two patients were Marfan syndrome. There were no aortic dissection patients.
Our indication for this particular surgery is dilated aortic root which is above 45 mm and the grade of AR greater than 2. Even if the grade of AR is 1, we add aortic annuloplasty to prevent future annular dilation. Operative methods were as follows. First, the left and right coronary ostia were harvested with a 3 mm button of surrounding aortic wall. The aortic wall was cut to within 5 mm of the leaflet and commissure. After resection of thinned and dilated aortic sinuses, 5-0 pledgetted horizontal mattress sutures were placed at the aortic annulus, from ascending aorta to left ventricular outflow tract site, using Gore-Tex strip (N. L. Gore and Associates, Arizona, USA) of 9 mm width and 0.6 mm thickness, located inside the aortic root so as to reduce its diameter and gain deeper coaptation. Five patients with no aortic valve disease were studied as controls. There were 2 women and 3 men, with a mean age of 69.4±7.5 years. They had normal systolic left ventricular function and a morphologically unremarkable aortic valve. TEE was indicated in this group of patients during a search for the source of cardiac embolism. All patients were in sinus rhythm. The individual examinations were performed after the patient had granted informed consent. The patients were evaluated by TEE pre and two weeks after the operation. TEE was performed with a 6-MHz multiplane probe- the Aloka SSD-5500 system (Aloka Corp., Tokyo, Japan). Data acquisition was triggered by electrocardiogram. The aortic root was evaluated at three levels: annulus, sinus of Valsalva, and sinotubular junction (ST junction). At each level, transaxial views were obtained. The diameter between the vertex and the aortic valve center were measured. Every diameter measurement was obtained at the systolic and diastolic phases of the cardiac cycle. Systolic diameter was obtained at the end of QRS complex as determined by electrocardiography (ECG). Diastolic diameter was obtained at the P wave of the ECG. Data analysis consisted of calculating the ratio of diastolic to systolic diameter of the distance between the vertex and the aortic valve center.
In the statistical analysis, results were given as mean±SD. Paired data were compared using the Wilcoxon signed-rank test, and unpaired data with the Kruskal–Wallis test, and the Mann–Whitney U test. Differences with
No early or late deaths occurred in this series during the follow-up period of 2 to 42 months (mean: 13.7±11.6 months). No endocarditis or thromboembolic events occurred. No patient was on oral anticoagulants or antiplatelets. All patients were in NYHA class I at the latest follow-up. Echocardiographic data are shown in Table 1. Clinically, all patients were judged to have good valve function throughout the follow up. The grade of AR was 3.2±1.0 before the operation and 0.4±0.7 at the latest follow-up. The results of the long axis view are shown in Fig. 1 and Table 1. Control data showed that the diameter of the sinus of Valsalva was the largest of the three parameters. The diameter of the ST junction was the second largest. The diameter of the annulus was the smallest. Although the diameters of the annulus and the ST junction were smaller in the diastolic phase than in the systolic phase, these differences were not significant. Pre-operative data showed that the same tendency as the control data. The diameters at the three levels were ranked as follows: the sinus of Valsalva was largest, the ST junction was second, and the annulus was smallest. Although the differences were not statistically significant, the diameters of the three levels in the diastolic phase were shorter than in the systolic phase. Post-operative data gave almost the same results as the former two groups: The diameter of the sinus of Valsalva was largest. That of the ST junction was second and that of the annulus was least. Although the difference was not statistically significant, the diameters of the three levels in the diastolic phase were smaller than in the systolic phase.
The results of the short axis view are shown in Fig. 2, and Table 2. The diameters between vertex and aortic valve center were measured. These data are indicated by the ratio of diastolic to systolic radius. Except for the control and the pre-operational ratio for the noncoronary cusp (NCC) at the annulus level, there were no statistically significant differences between the groups. There were, however, definite trends in the results. First, the ratios for the ST junction level were below 1. This means that the radius of the aorta at the ST junction is larger in systole than in diastole. Second, the ratios of post-operational radii are almost 1 at the sinus of valsalva level. This means the radii at the sinus of Valsalva level are almost constant during the cardiac cycle. Third, the ratio of at the annulus was biggest in the control and post-operative groups, except for the right coronary cusp (RCC). This means that the radius at the level of annulus is larger in diastole than in systole.
Histologic examination of Marfan syndrome patients revealed that the aortic wall was cystic medial necrosis.
There have been many reports on aortic root motion during the cardiac cycle in non-human subjects [11–13]. In this study, we investigated the dynamic dimensions of diseased and repaired human aortic roots during the cardiac cycle. Echocardiography of the long axis view revealed that the Valsalva diameter was largest in the three-dimensions, the ST junction was second largest, and the annulus was smallest. This trend was invariant with phase (systolic vs diastolic), and between the pre-operative and post-operative measurements. In contrast with our data, those of Kunzelman et al. [14] showed that the Valsalva dimension was largest, the annulus was second largest, and the ST junction was smallest. One obvious reason for this difference is that our measurements were acquired under normal human blood pressure, whereas their data were measured under atmospheric pressure, because their data were obtained from the cadavers. And the anatomical dissimilarities of different species must be considered. Control data and post-operative data show a similar tendency in the diastolic: systolic length ratio. Both groups showed that the dimensions of the annulus and the ST junction in the systolic phase are larger than in the diastolic phase. And, the dimension of Valsalva in the systolic phase is smaller than in the diastolic phase. On the other hand, pre-operative data showed that the three diameters are smaller in the systolic phase than in the diastolic phase. The reason for this paradoxical motion may be related with AR. Blood flow reverses during the diastolic phase because of AR. Aortic pressure decreases during diastole, and the aortic wall shrinks. Once surgery has restored aortic valve competence, the aortic root moves as in the control group. An important feature of this data is that subvalvular circular annuloplasty does not alter annulus motion during the cardiac cycle. Echocardiography of the short axis view was evaluated by the ratio of diastolic to systolic radius. In the control data, the rate of diameter change (distensibility) during the cardiac cycle was largest at the annulus level: those at the Valsalva level and the ST junction were almost the same. The annulus was the most changeable in the three dimensions. The radius of the RCC did not change between the systolic and diastolic phase. On the other hand, the radius of the left coronary cusp (LCC), and the NCC changed their length during the cardiac cycle. This is because of the surrounding components of the aortic root. Exterior to the RCC is a muscular portion of the heart that is contiguous with the right ventricle. Outside the LCC and NCC is the aortic curtain, which is the aorto-mitral junction. The motions of the NCC and LCC correlate with mitral valve motion during the cardiac cycle. Lansac et al. [15]. pointed out that, in systole, the anterior mitral annulus expanded (intertrigonal distance: +11.5±2.3%) and the posterior mitral annulus contracted (distance between lateral extremities of the posterior annulus: –12.1±1.5%). The intertrigonal distance corresponded to the base of the left and noncoronary sinuses of Valsalva, which expanded similarly during systole (+12.9±2.0%). Pre-operational measurements showed that NCC and LCC did not become longer at the diastolic phase. Although the difference between pre-operational measurements and rest of groups were not significant, the way of aortic root motion during cardiac cycle may be different. Post-operative ratios showed that the modes of change at the annulus level were not significantly different to the control data. NCC and LCC changed most during the cardiac cycle, but RCC did not changed. This indicates that subvalvular circular annuloplasty restored distensibility to the annulus. At the Valsalva level, the radii of the three cusps were almost identical throughout the cardiac cycle. One of the reasons for this is that the tailored graft fixed the Valsalva level so that its length was virtually invariable. These figures make clear that subvalvular circular annuloplasty may play a major role in treating AR and restoring the near normal morphology of the aortic root. Also it does not alter the dynamics of the aortic root especially at the annulus. This technique uses a Gore-Tex strip (N. L. Gore and Associates, Arizona, USA), which has a degree of flexibility. At every level, at every part, the rate of change was within 25%, that is approximately 0.5–0.6 cm. The Gore-Tex strip can cope with this change. The effect of subvalvular circular annuloplasty is to tighten the annulus and to obtain a deeper coaptation zone, in order to treat AR, and to secure the annulus, preventing future re-dilatation. The results of histologic examination might have some influence on the long- term, but it is still unclear at this point. 4.1. Study limitations There are several limitations to this study. Echocardiography does not always provide the same results. However, because echocardiographic examination was performed by a single experienced, and interpretation of the data was by a single echocardiographer, the error range due to subjectivity was minimal.Inspection by TEE required considerable patience. It was only practical to take two points during the cardiac cycle. Because we could not examine many other points during the cardiac cycle, reconstructing the time-varying, three-dimensional image of aortic root was difficult. Although the inspection was imperfect, the dependence on cardiac cycle phase and aortic root morphology can be appreciated. In conclusion, we demonstrated important differences in aortic root motion during the cardiac cycle. The near normal pattern of the aortic root motion after aortic root remodeling with concomitant aortic annuloplasty is associated with correction of aortic root morphology and AR. Subvalvular circular annuloplasty did not hinder the motion of the aortic root. In order to determine whether the observed differences in aortic root motion in the three groups affect cardiac performance and valve durability, long-term follow up is mandatory.
Conference discussion Dr S. Hagl (Heidelberg, Germany): What are you doing with this subvalvular circular annuloplasty? Do you form a more or less rigid ring? Dr Kazui: No. We use a Gore-Tex strip, which is quite flexible, I think, and in this paper I think we could show the distensibility of using a Gore-Tex strip to recreate the aortic annulus. Dr Hagl: Does this have any implications or any disturbance of transaortic flow? Dr Kazui: In this paper we cannot verify that, but in the future we want to verify that excellent flow can be obtained.
We would to thank Norihiko Itoh for his effort in obtaining TEE data, which was essential to the completion of this study.
Presented at the joint 17th Annual Meeting of the European Association for Cardio-thoracic Surgery and the 11th Annual Meeting of the European Society of Thoracic Surgeons, Vienna, Austria, October 12–15, 2003. doi:10.1016/j.icvts.2004.03.008
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Abstract
1. Introduction
were considered statistically significant. 
