Ann Thorac Surg 2009;88:1238-1243. doi:10.1016/j.athoracsur.2009.05.048
© 2009 The Society of Thoracic Surgeons
Original Articles: Adult Cardiac
Adjustment of Sinotubular Junction for Aortic Insufficiency Secondary to Ascending Aortic Aneurysm
Naoto Morimoto, MD*,
Masamichi Matsumori, MD,
Akiko Tanaka, MD,
Hiroshi Munakata, MD,
Kenji Okada, MD,
Yutaka Okita, MD
Division of Cardiovascular Surgery, Kobe University Graduate School of Medicine, Kobe, Hyogo, Japan
Accepted for publication May 13, 2009.
* Address correspondence to Dr Morimoto, Division of Cardiovascular Surgery, Kobe University Graduate School of Medicine 7-5-1, Kusunoki-cho, chuo-ku, Kobe, Hyogo, 650-0017, Japan (Email: naotofrcs{at}gmail.com).
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Abstract
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Background: Dilatation of the sinotubular junction (STJ) causes aortic regurgitation (AR) in patients with ascending aneurysm. These patients can regain valve competence by simple reduction of the diameter of STJ. Results of this technique were investigated clinically and echocardiographically.
Methods: Replacement of the ascending aorta with reduction of the diameter of the STJ to correct AR (mean grade, 2.7 ± 0.7) was performed in 29 consecutive patients (mean age, 73.2 ± 6.2). Two required repair of cusp prolapse. All underwent ascending aortic aneurysm replacement. Echocardiographic studies were performed at discharge and during latest clinical follow-up (mean follow-up, 3.8 ± 2.5 years).
Results: No hospital deaths occurred. The AR grade at discharge was 0.7 ± 0.5. No valve related-deaths occurred. Actual survival at 8 years was 91% ± 9%. Failure occurred 4.1 years postoperatively in a patient with bicuspid valve. Three patients had late recurrence of AR that was caused by aortic root dilatation in bicuspid valves in 2. Multivariate analysis showed bicuspid aortic valve was the predictor of late progression of AR. The freedom from more than grade II AR at 8 years was 79.5% ± 10.7%.
Conclusions: Adjustment of the diameter of STJ could treat AR secondary to ascending aortic aneurysm with nearly normal aortic cusps. Midterm results of this procedure were acceptable. Although bicuspid aortic valve is the risk factor for late AR due to dilation of remaining aortic root, this procedure provides satisfactory long-term outcomes among the patients with tricuspid valve.
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Introduction
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The aortic root provides the supporting structures for the leaflets of the aortic valve and is important in aortic valve competence. The root consists of the basal ring, interleaflet triangle, sinus of Valsalva, and sinotubular junction (STJ) [1]. The dilatation of each component may alter the dimension of the valve leaflets, causing aortic regurgitation (AR). AR accompanied with aortic root aneurysm can be treated by surgical correction of most anatomic components of the aortic root. However, for the AR accompanied with an ascending aortic aneurysm, simple reduction of its diameter can restore valve competence because the AR is caused by dilatation of the STJ. This study investigated the clinical and echocardiographic results of replacement of the ascending aorta with reduction of the diameter of STJ to correct AR in patients with ascending aortic aneurysm and normal sized aortic sinuses.
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Patients and Methods
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This retrospective cohort study was approved by our local Institutional Review Board, which waived the need for patient consent because of the retrospective nature of the study. From October 1999 to February 2008, 107 consecutive patients with ascending aortic aneurysm and AR were operated on at Kobe University Hospital. Ascending aortic aneurysm was defined as a dilatation exceeding 50 mm of one or more segments of the proximal thoracic aorta.
Of these patients, 52 patients had aortic valve-sparing reimplantation, 26 underwent a Bentall procedure, and 29 had ascending aortic replacement and reduction of the STJ diameter. We excluded from analysis a patient who had acute aortic dissection, chronic dissection with commissural detachment, and mild or no AR. Table 1
reports the preoperative demographics of the patients.
Preoperative Echocardiographic Assessment
All patients were examined preoperatively with transthoracic and transesophageal echocardiography. After the cardiovascular structures were analyzed, a standard was used to carefully explore the aortic valve and the ascending aorta. The following variables were obtained by an average of 3 consecutive beats:
Regurgitation severity grading was quantitative and was based on regurgitant volume, regurgitant fraction, and effective regurgitant orifice area. The AR severity was graded as I = trace, grade II = mild, grade III = moderate, and grade IV = severe. Different levels of aortic root diameter (basal ring, mid-sinus, and STJ) were measured, guided by M-mode tracking using cross-sectional echocardiography in the long-axis view. Preoperative mean AR grade was 2.7 ± 0.7, regurgitant volume was 39.7 ± 30.8 mL, regurgitant fraction was 34.8% ± 10.9%, and effective regurgitant orifice area was 0.31 ± 0.15 cm2. Aortic root diameters were obtained at maximum anterior motion of the aorta and at the peak of the QRS complex using following criteria:
- • Basal ring (mm): the distance between the insertion of the basal valve cusps into the aortic root;
- • Mid-sinus (mm): maximum distance between the Valsalva sinuses;
- • STJ (mm): dimension of the aortic root at the level of commissural cusp-tip insertion into the aortic wall.
Preoperative mean diameters of basal ring, mid-sinus, STJ, and ascending aorta were 21.6 ± 1.6 mm, 37.4 ± 3.7 mm, 35.1 ± 4.8 mm, and 57.5 ± 10.8 mm, respectively. Figure 1
shows the relationship diameter of STJ or ascending aorta and AR grade. For the relationship between AR grade and aortic diameters, AR grade was significantly correlated with diameter of STJ (Spearman correlation coefficient r = 0.61, p < 0.001) and ascending aorta (r = 0.52, p = 0.01). In addition, stepwise linear logistic regression analysis showed an independent correlation between the STJ diameter and the AR grade (β = 0.52, p = 0.01).
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Fig 1. Scheme shows the relationship between the grade of aortic regurgitation and the diameters of the sinotubular junction and ascending aorta.
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Patient Selection
AR complicated by an ascending aortic aneurysm was surgically treated by aortic root replacement or reduction of the diameter of STJ. The current indication for valve-sparing aortic root replacement included an aortic mid-sinus diameter exceeding 45 mm in non-Marfan patients and exceeding 40 mm in Marfan patients, patients with aortic mid-sinus diameter increasing more than 1 cm/y, and age younger than 70 years.
The indication for adjustment of STJ was (1) normal diameter of the aortic annulus (<25 mm) and mid-sinus (<40 mm), (2) incomplete aortic cusp coaptation caused by dilatation of STJ (>30 mm), (3) minimal degenerative change in aortic cusps (small fenestrations, mild fibrosis/sclerosis, and the absence of calcifications), (4) central aortic regurgitation, and (5) normal ventricular performance without any episodes of congestive heart failure (Fig 2). Although it was possible to select patients for this procedure by assessing the preoperative echocardiogram, the final decision was made by inspecting the aortic root and aortic cusps intraoperatively.
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Fig 2. (A–E) Preoperative transesophageal echocardiography and (F) postoperative transthoracic echocardiography. (A) The diameter of the sinotubular junction aorta was dilated to 33.7 mm. (B, C) Aortic valve with minimal degenerative change. (D, E) Central aortic regurgitation. (F) The diameter of the sinotubular junction was adjusted and aortic valve function was competent.
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Operation
The neck of ascending aortic aneurysm was a few centimeters above the aortic valve. Although the STJ is not easily identifiable, the ascending aorta was transected 1 cm above the level of each commissure post. Adjustment of the diameter of the STJ was performed by suturing a tubular Dacron (DuPont, Wilmington, DE) graft in all patients. To prevent misalignment of commissure posts, the circumference of STJ was divided into 3 intercommissural parts by placing 3 stay stitches at each commissure post. The intercommissural distance was adjusted by anastomosing these 3 parts to the graft with same reduction rate. The diameter of graft was 22 or 24 mm in the patients whose body surface area was less than 1.5 mm2. When the patient's body surface area exceeded 1.5 mm2, a 26-mm graft was selected according to the size of basal ring.
Two patients had prolapse of 1 cusp and the free margin was shortened by plicating along the nodule of Arantii. Concomitant aortic procedures included hemiarch replacement in 22 patients, total arch replacement in 6, replacement of the entire thoracic aorta in 1, and replacement of abdominal aorta in 1 (Table 2).
Follow-Up
Clinical and echocardiographic follow-up was complete in all patients. Postsurgical echocardiographic studies were performed at discharge and at the latest clinical follow-up.
Statistical Analysis
Comparisons between the two groups with and without late progression of AR were performed with the t test for normally distributed data. Proportions were analyzed by 
2 or F test, as appropriate. A two-sided error level of p < 0.05 was considered statistically significant. Variables significantly associated with late progression of AR in univariate analysis were entered into a multivariate logistic regression analysis. For correlation analysis, Spearman correction coefficient (r) was used. Statistical analysis was computed with SPSS 11.5 software (SPSS Inc, Chicago, IL).
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Results
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Hospital Death and Morbidity
No patients died in the hospital. Two patients had a stroke intraoperatively. Nine patients had atrial fibrillation postoperatively. There was no other in-hospital complication.
Echocardiographic Analysis at Discharge
The amount of AR determined intraoperatively by the color Doppler technique was 2.7 ± 0.8 preoperatively and 0.7 ± 0.5 postoperatively (p < 0.001). Diameter of STJ was reduced from 35.1 ± 4.8 to 27.0 ± 3.1 mm (Fig 3) The amount of AR documented at discharge was the same as at the intraoperative findings. On the echocardiographic quantification at discharge, regurgitant volume was 9.9 ± 10.0 mL, regurgitant fraction was 10.3% ± 7.2%, and the effective regurgitant orifice area was 0.05 ± 0.06 cm2 and showed significant decrease compared with preoperatively (p = 0.02, p < 0.001, p = 0.001, respectively). The left ventricular end-systolic and end-diastolic volume indices were 57.6 ± 48.7 mL/m2 and 25.5 ± 26.4 mL/m2, respectively. The left ventricular ejection fraction was 0.573 ± 0.111. The New York Heart Association class decreased from 1.7 ± 0.7 to 1.1 ± 0.3 (p < 0.001).
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Fig 3. Scheme shows postoperative change in the grade of aortic regurgitation in 29 patients after the operation. Bicuspid valve patients are shown as broken lines, whereas tricuspid valve patients are shown as solid lines.
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Late Death and Morbidity
Late death occurred in 1 patient. This patient underwent thoracoabdominal aortic repair 3 years after first operation and died of postoperative pulmonary embolism. There was no valve-related death. The actual survival was 91% ± 9% at 8 years. Thromboembolic events and infective endocarditis were not noted in the postoperative follow-up. Two patients were receiving warfarin sodium for atrial fibrillation. There was no anticoagulant-related hemorrhage. A pacemaker was implanted in 1 patient for sick sinus syndrome 7.2 years postoperatively.
Reoperation
Recurrent AR requiring reoperation developed in 1 patient (3.4%). This 72-year-old woman had bicuspid aortic valve, and the echocardiography showed grade I AR postoperatively. She experienced dyspnea on exertion 4 years later and palpitation and echocardiography revealed grade IV AR. At reoperation, the diameter sinus of Valsalva had enlarged from 40 to 47 mm and aortic cusp shrinkage had caused inadequate leaflet coaptation. The valve was replaced. Two patients had operations for aneurysm of thoracoabdominal aorta, and 1 died as described.
Echocardiographic Follow-Up
Mean AR grade and its quantification showed no statistically significant difference between the echocardiogram at discharge and at the latest follow-up. Evidence of late progression of AR was found in 3 patients (Fig 4). Although the diameters of aortic annulus, sinus of Valsalva, and sinotubular junction were stable postoperatively in patients with a tricuspid valve, in 2 of the 3 patients who had a bicuspid aortic valve, echocardiography revealed progressive increase in AR grade with concomitant aortic root dilatation (Fig 2). Multivariate logistic regression analysis showed bicuspid aortic valve was predictor of late progression of AR grade more than II (odds ratio, 24.0; 95% confidence interval, 1.5 to 394.8; p = 0.03, Table 3). Actual freedom from more than grade II AR was 72.0% ± 17.8% at 8 years (Fig 5).
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Fig 4. Changes in aortic root dimension at three levels (base, mid-sinus, and sinotubular junction) are shown on serial echocardiograms (preoperative, at discharge, and latest follow-up). Although the size of aortic root dimension was stable in patients with tricuspid valve, the diameter of the mid-sinus had tendency to increase during the follow-up period in those with bicuspid valve.
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Comment
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Aortic root dilatation is the most common cause of isolated AR. The mechanism by which the aortic valve opens and closes involves the whole aortic complex, composed of supporting interleaflet triangles, commissures, basal ring, sinus of Valsalva, and ascending aorta [1]. Therefore, despite normal aortic valve leaflets, an abnormality in the structures that support the valve at the moment of closure can cause AR. Frater [2] defined this type of AR as functional AR. Adjustment of the supporting structures has long been accepted as a treatment for functional AR. In patients with annuloaortic ectasia, aortic valve-sparing procedures have gained popularity. The standard operation for patients with ascending aortic aneurysm and AR has been aortic valve replacement and supracoronary replacement of the ascending aorta.
This mechanism of AR secondary to dilatation of the diameter of the STJ was clearly described by Corrigan [3]. Dilation of the STJ displaces the commissures away from each other and holds the cusps permanently open. This hypothesis was validated by experimental study [4]. Simple reduction of the STJ diameter restores valve competence if the cusps are normal. In 1986 Frater [2] first described preservation of the aortic valves by the adjustment of dilated STJ in 5 patients with dilation of ascending aorta causing AR. David and associates [5] recently demonstrated their experience of this procedure in 103 patients with AR secondary to an ascending aortic aneurysm.
The typical features of anatomy in AR secondary to dilatation of STJ are a normal or minimally dilated aortic root and normal cusps. However, the longstanding hemodynamic alternation in the aortic root increases the stress on the cusps, and they may become elongated or develop fenestrations in the commissural areas, or both. Cusp prolapse is often noted in these patients. David and associates [5] described that additional aortic valve repair was required for aortic valve prolapse in 28% of their series. We encountered 2 patients (6%) with cusp prolapse and corrected it by plicating the elongated free margin along the nodule of Arantii with a 6-0 polypropylene suture. This cusp procedure does not seem to increase the risk of late AR, and we have expanded the indications for aortic valve repair.
Bicuspid aortic valve was only risk factor of recurrent AR on our analysis. Late progression of AR was noted in 2 of 3 patients (66%) who had bicuspid valve. The findings in the patient requiring reoperation were dilatation of sinus of Valsalva and leaflet shrinkage. Dilatation of the aortic root may stretch the aortic leaflets after compensatory elongation and thickening of the free margin of the aortic valve, causing AR [6, 7]. Thus, future dilatation of sinus of Valsalva is a potential hazard of reduction of the diameter of STJ.
Aortic dilatation can occur in patients with a hemodynamically normal bicuspid aortic valve [8]. According to results of 46 patients undergoing bicuspid aortic valve repair described Alsoufi and associates [9], dilatation of the aortic root will be a common cause of AR and a common feature of these patients. Thus, this operation is not preferable in patients with abnormal aortic elastic abnormalities, including bicuspid aortic valve, Marfan syndrome, and other connective tissue disorder. When the aortic valve can be preserved in these patients, aortic valve reimplantation or remodeling should be performed to replace the entire proximal aorta.
The diameter was the graft was selected according to the technique described by Morishita and colleagues [10]. The ascending aorta was transected 1 cm above the STJ, and 3 commissures were pulled up with stay sutures. With the aortic cusps coadjusted centrally, the diameter of imaginary circle that includes all commissures was the estimated diameter of the STJ. If the diameter was less than 24 mm, a graft of this size or larger was selected and the diameter of the STJ was reduced to the graft size, except for 3 patients whose body surface areas were less than 1.3 mm2. Measurement studies of normal human aortic root [11, 12] show that the STJ is approximately 30% larger than the annulus. In our study, the mean diameter of the annulus and the graft size were 21.6 and 24.2 mm, respectively. We believe that our mean graft size of 24.2 mm (12% greater than diameter of the annulus, 21.1 mm) was proper because the diameter of Dacron aortic graft increased 30% after the implantation.
Patients with ascending aorta aneurysm and secondary AR are usually older than patients with aortic root aneurysm [13] and have more extensive aneurysmal disease, with frequent involvement of the transverse arch and remaining thoracic and sometimes the abdominal aorta. Our patients were a mean age of 72.9 years, and 38% required simultaneous total arch replacement. Reducing the diameter of STJ is much easier and quicker than valve replacement and is more beneficial to older patients. If the sinus or aortic annulus is dilated, younger patients are good candidate for an aortic valve-sparing operation such as reimplantation. Three patients who were older than 75 year underwent total arch replacement and the reduction of STJ, although their sinuses of Valsalva were moderately dilated.
In conclusion, aortic valve sparing to treat patients with ascending aortic aneurysm with AR resulting from dilation of the STJ is a relatively simple and quicker than aortic valve replacement. Aortic valve function remains stable for many years, and valve-related events are rare. Although bicuspid aortic valve is a risk factor for late AR due to dilation of the remaining aortic root, this procedure provides satisfactory long-term outcomes among the patients with tricuspid valves.
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References
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Abstract
Introduction
