Eur J Cardiothorac Surg 2008;34:37-41. doi:10.1016/j.ejcts.2008.03.065
Copyright © 2008, European Association for Cardio-thoracic Surgery. Published by Elsevier. All rights reserved.
Long-term results of Konno procedure for complex left ventricular outflow tract obstruction
Takahiko Sakamoto*,
Goki Matsumura,
Yoshimichi Kosaka,
Yusuke Iwata,
Noboru Yamamoto,
Satoshi Saito,
Kazuaki Ishihara,
Hiromi Kurosawa
Department of Cardiovascular Surgery, The Heart Institute of Japan, Tokyo Women's Medical University, 8-1 Kawada-cho, Shinjuku-ku, Tokyo 162-8666, Japan
Received 22 September 2007;
received in revised form 22 March 2008;
accepted 31 March 2008.
* Corresponding author. Present address: Nagano Children's Hospital, Japan. Tel.: +81 3 3353 8111; fax: +81 3 3356 0441. (Email: takasakamoto{at}yahoo.co.jp).
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Abstract
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Objective: The current study aims to evaluate the long-term outcomes of the Konno procedure. Methods: The clinical records of 63 patients who had undergone the Konno procedure between February 1984 and March 2007 were reviewed. During this period, the Ross procedure was introduced in 1996. Of the 63 patients, 38 were male and 25, female. Their ages at the time of operation ranged from 1 year 9 months to 37 years, and their body weights ranged from 8.1 to 63 kg. Valves larger than 23 mm were used in 57 patients. Results: There was one hospital death (myocardial infarction) and six late deaths (sudden death, 2; congestive heart failure, 2; infectious endocarditis, 1; traffic accident, 1). The Kaplan–Meier survival rates including hospital mortality and late mortality were 91.9% at 10 years and 87.7% at 15 years. There were 20 significant complications in 16 patients: thromboembolism was noted in 1 patient; reoperations (Konno procedure (aortic valve replacement), 5 (thrombosed valve, 3; pannus formation, 1; IE, 1); mitral valve replacement, 3; coronary artery bypass grafting, 2; grafting of the descending aorta, 1), balloon dilatation for recoarctation, and 7 catheter interventions were required in 9, 1, and 5 patients, respectively. The event-free rates including all events were 75.2% at 10 years and 67.2% at 15 years. In the long-term period, the results of echocardiography revealed good cardiac function. Conclusions: The Konno procedure is effective and safe for the treatment of complex left ventricular outflow tract obstruction and for the preservation of ventricular function. Since some issues concerning anticoagulation-related complications and infectious endocarditis remain, careful observation is mandatory.
Key Words: Konno procedure • Ross procedure • Long-term outcomes
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1. Introduction
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The surgical management of complex left ventricular outflow tract (LVOT) obstruction has developed over three decades, and it continues to undergo further development. The Konno procedure was first performed in October 1974 and was reported in 1975 [1]. In this procedure, the proximal aorta and LVOT are simultaneously enlarged, and it is therefore considered to be an effective measure to relieve severe LVOT obstruction associated with aortic root narrowing. However, the effect of extensive incision into the ventricular septum on left ventricular (LV) function and conduction disturbance needs to be clarified [2]. Moreover, the use of the Konno procedure with mechanical or bioprosthetic valves for LVOT obstruction in children poses potential risks of chronic anticoagulation, infectious endocarditis (IE), and valve degeneration [3]. On the other hand, the Ross procedure, which was first reported in 1967, involves aortic valve replacement with a pulmonary autograft [4]. The Ross procedure is considered to be a novel method since the autograft may grow and since anticoagulation is not required, and it has become popular for its application in the surgical treatment of LVOT obstructions (currently, the Ross procedure is the first choice for this treatment at our institute.). However, the Ross procedure may not be suitable in some cases; therefore, the Konno procedure continues to play a significant role. The current study aims to evaluate the long-term outcomes of the Konno procedure.
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2. Patients and methods
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Since 1984, we have performed the Konno procedure by using mainly St. Jude Medical prostheses (SJM). The clinical records of 63 patients who had undergone the Konno procedure between February 1984 and March 2007 were reviewed. The Ross procedure was introduced in 1996, and a total of 68 patients underwent this procedure in the above-mentioned period. Of the 63 patients who had undergone the Konno procedure, 38 were male and 25, female. At the time of operation, their ages ranged from 1 year 9 months to 37 years (mean, 11.3 ± 7.7 years), and their body weights ranged from 8.1 to 63 kg (mean, 31.1 ± 15.2 kg). The cardiopulmonary bypass (CPB) time was 174.8 ± 40.5 min, and the aortic cross-clamp time was 108.4 ± 21.3 min. The mean follow-up period was 13.4 ± 6.2 years. All data were evaluated at the end of August 2007 (Fig. 1
).
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Fig. 1. Number of operations. A total of 131 patients underwent either the Konno procedure (n
= 63) or the Ross procedure (n
= 68) between February 1984 and March 2007. The Ross procedure was introduced in 1996.
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The indications for operation were aortic stenosis (AS) in 24 patients, aortic stenosis and regurgitation (ASR) in 31 patients, aortic regurgitation (AR) in six patients, and infectious endocarditis (IE) in two patients. The principal concomitant procedures were mitral valve replacement (MVR) in five patients, coronary artery bypass grafting (CABG) in two patients, left ventriculoplasty in one patient, aneurysmorrhaphy of Valsalva aneurysm in one patient, and atrioventricular groove patch plasty in two patients.
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3. Operative technique
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With the patient under fentanyl anesthesia, a median sternotomy is made. CPB is started with ascending aortic perfusion and direct bicaval drainage accompanied by left atrial (LA) venting. First, a right ventricular (RV) incision is made parallel to the pulmonary artery (PA) ring and 5 mm proximal to it; this incision is extended toward the aortic root. After aortic cross-clamping and the induction of cardioplegia, the ascending aorta is longitudinally opened along its left anterior wall down to the commissure between the left and right coronary cusps. Next, the aortotomy incision is extended 20–30 mm into the ventricular septum, parallel to the PA ring and 5 mm proximal to it. The aortic cusps are excised, and half the circumference of a mechanical prosthesis is embedded in the original aortic valve ring. The septal incision is closed with the lower one-third of a composite patch. The remaining sewing ring of the valve is fixed to the aortoventricular patch, whereby the RV patch is simultaneously fixed to the latter. The aortic incision is enlarged with the upper two-thirds of the aortoventricular patch. After the aorta is unclamped, the RV incision is closed with the RV patch.
Fig. 2
shows the correlation between the aortic annular diameter and the age at the time of the Konno operation. The preoperative aortic annular diameter was less than 20 mm in 80% of the patients. Sixty-two mechanical valves (59 SJM, 1 Bicarbon, 1 CarboMedics, and 1 ATS) and 1 biological valve (Carpentier–Edwards pericardial valve (CEP)) were implanted. The valve size was fundamentally decided as 25 mm for the males and 23 mm for the females, and valves larger than 23 mm were used in 57 patients (90.5 %) (Fig. 3
).
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Fig. 2. Correlation between aortic annular diameter and age at the time of the Konno operation. The preoperative aortic annular diameter was less than 20 mm in 80% of the cases.
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Fig. 3. Size of prosthesis implanted during the Konno procedure. The valve size was fundamentally decided as 25 mm for males and 23 mm for females. In 57 patients (90.5%), a mechanical valve larger than 23 mm was implanted.
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4. Statistical analysis
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All the results were expressed as mean ± standard deviation of the mean. Time interval curves were constructed by the Kaplan–Meier product limit method. All data were analyzed with a statistical analysis software package (StatView 5.0, Abacus Concepts, Berkeley, CA).
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5. Results
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There was one hospital death and six late deaths. A 3-year-old boy died of perioperative myocardial infarction on the 9th postoperative day. The mean duration from the operation to late death was 4.9 ± 5.0 years. The causes underlying the late deaths were sudden death (2), congestive heart failure (CHF) (2), IE (1), and a traffic accident (1). The Kaplan–Meier survival rates including hospital mortality and late mortality were 91.9% at 10 years and 87.7% at 15 years (Fig. 4
).
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Fig. 4. Overall survival rate. The actuarial survival rates calculated with the Kaplan–Meier curves were 91.9% at 10 years and 87.7% at 15 years.
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There were 20 significant complications in 16 patients: thromboembolism was noted in one patient. Reoperation (Konno procedure (AVR) in five (thrombosed valve, 3; pannus formation, 1; IE, 1), MVR in three, CABG in two, and grafting of the descending aorta in 1) was conducted in nine patients. Balloon dilatation for recoarctation was required in one patient and seven catheter interventions, in five patients. Event-free rates including all mortality and reoperation were 86.7% at 10 years and 78.0% at 15 years (Fig. 5
). Those including all mortality, reoperation, catheter intervention, and significant complications were 75.2% at 10 years and 67.2% at 15 years (Fig. 6
).
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Fig. 5. Freedom from death and reoperation. Event-free rates including all mortality and reoperation were 86.7% at 10 years and 78.0% at 15 years.
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Fig. 6. Freedom from all events. Event-free rates including all mortality, reoperation, catheter intervention, and significant complications were 75.2% at 10 years and 67.2% at 15 years.
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In the long-term period, the results of echocardiography were as follows: LV shortening fraction (LVSF), 0.34 ± 0.08; estimated RV pressure, 48.9 ± 15.5 mmHg, and LVOT flow, 2.2 ± 0.8 m/s. All the long-term survivors (56) were in either NYHA class I or II.
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6. Discussion
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The current study demonstrated that the Konno procedure is effective and safe for the treatment of complex LVOT obstructions and for the preservation of ventricular function. However, some issues concerned with anticoagulation-related complications or IE remain.
6.1 Surgery for complex LVOT obstruction
The primary surgical plan for congenital aortic valve stenosis or subaortic stenosis is usually valvotomy or resection of the hypertrophied muscle. Catheter balloon dilatation is also considered effective for aortic valve stenosis in children [5]. However, patients with both valvular and subvalvular lesions require extensive surgery for anatomical reasons. In addition, the first intervention, either valvotomy and balloon plasty, yields palliative effects, and LV function might gradually decrease in the long-term period. A new episode of aortic regurgitation might occur after the first intervention. Continuous pressure overload leads to LV hypertrophy and decreased compliance. In addition, volume overload due to aortic regurgitation may result in LV dilation. Therefore, complex LVOT lesions should generally be treated by extensive surgery within the appropriate period. Procedures for mild annular enlargement can easily yield prostheses of an adequate size for adult patients even if the aortic annulus in these patients is small. However, in the case of infants or small children, particularly those with subaortic lesions, an aggressive approach such as one involving the Konno or Ross procedure is required. The Konno procedure was reported in 1975 as a novel aortoventriculoplasty technique, and it is well known to effectively enlarge the LVOT [1]. However, the long-term effects of ventricular septum incision on LV function are unknown, and the Konno procedure usually involves mechanical valves, which necessitate anticoagulation. The Ross procedure was proposed in 1967 [4], and its use was revived in the 1990s after technical difficulties were overcome [6,7]. This procedure is considered to be superior because it does not necessitate anticoagulation and the autograft may grow [8]. Owing to these reasons, the frequency at which the Ross procedure is conducted at our institute has increased. However, this procedure may not be suitable in some cases such as those of AR after repair of truncus arteriosus or tetralogy of Fallot; therefore, the Konno procedure must be selected in such cases.
6.2 Advantage of the Konno procedure
The main advantage of the Konno procedure when compared with simple aortic valve replacement is that it enables the insertion of an appropriately sized prosthesis even in the case of small children. The Nicks procedure is one of the aggressive surgical procedures used to correct LVOT obstruction. It is used to extend the aortotomy through the noncoronary cusp, across the aortic ring, and into the fibrous continuity, whereby the hypoplastic aortic annulus can be enlarged. This procedure enables the insertion of a valve that is one or two sizes larger than the measured size of the native aortic annulus [9]. The Manouguian procedure is more aggressive than the Nicks procedure; if the former is used, great care should be taken in the case of new-onset mitral regurgitation, which is a common complication occurring at a frequency of 0–14% [10–13]. Further, the new method proposed by Yamaguchi et al. enables the implantation of a prosthesis that is four sizes larger than the measured size of the native aortic annulus [14]. This procedure may be helpful in the case of small children if it is used with supra-annular valve models such as St. Jude Hemodynamic Plus or Regent because extensive incision into the ventricular septum, as is required in the Konno procedure, can be avoided. However, the above-mentioned procedures are of no use in the case of severe subaortic lesions. In contrast, the Konno procedure allows almost unlimited enlargement of the LVOT. On the basis of this theoretical background, we have decided to use 23 mm SJM for females and 25 mm SJM for males in order to curtail the need for reoperation in adulthood. As shown in Fig. 3, in most cases, we could employ a 23 mm prosthesis for patients over 3 years of age and a 25 mm prosthesis for patients over 10 years of age or older. This indicates that for this type of repair, prosthetic valves of the sizes used for adults can be implanted in most patients over 3 years of age.
Another advantage of the Konno procedure over other procedures such as aortic root replacement is the low incidence of postoperative conduction disturbance. The new appearance of a complete right bundle branch block was observed in 14 cases (22%). However, a new AV block was not observed in any case. Conduction disturbance can be prevented if the septal incision is made at a distance from the medial papillary muscle, 5 mm proximal to and parallel to the PA ring [15].
6.3 Long-term outcome of the Konno procedure
In the Konno procedure, a mechanical valve and a patch for the ventricular septum are usually used. These materials might pose a greater risk of thromboembolism, infection, and calcification than those used in the Ross procedure or aortic root replacement with a homograft. In fact, one thromboembolism and four valve malfunctions (thrombosed valve, 3; pannus formation, 1) were observed in the current study. This issue is related to the difficulty of anticoagulation control in children even under careful management. In addition, other risks associated with the use of mechanical valves versus the use of bioprosthetic ones in AVR have been reported [16].
There have been some cases in which right ventricular outflow tract (RVOT) reconstruction or a related intervention was conducted in the long-term period. However, in these patients, peripheral pulmonary artery stenosis was addressed, and no stenosis was recognized at the subpulmonary/RV outflow region. The stenosis of the peripheral pulmonary artery is not a Konno procedure-related one. This issue has emerged because the indications of the Konno procedure have been extended to complex cardiac anomalies rather than merely aortic/subaortic stenosis.
LV function after atrioventriculoplasty is important because the Konno procedure involves a longitudinal aortoseptal incision through an RV incision [17]. In the original illustration, the septal incision was made at a distance from the PA in the proximity of the conduction system [1]. However, the incision must be made parallel to the PA ring. This modification could lead to the maintenance of the LV function and prevent new-onset AV block [15]. In addition, it is important to prevent damage to the first septal branch of the left anterior descending coronary artery [18]. It should be noted that the LVSF in two patients was less than 0.20 in the long-term period. This might be associated with the paradoxical motion of the ventricular septum or may eventually lead to poor myocardial protection for the severely hypertrophied LV myocardium. Further, in addition to the Konno procedure itself, concomitant procedures such as coronary artery surgery, left ventriculoplasty, and MVR may affect the LV function.
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7. Conclusions
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The Konno procedure is effective and safe for the treatment of complex LVOT obstructions and for the preservation of LV function, although some issues concerned with anticoagulation-related complications and IE remain, due to which careful observation is mandatory.
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Appendix A
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Conference discussion
Dr G. Sarris (Athens, Greece): Let me open the paper for discussion with a comment and a question to you that pertains to the two groups of patients. It seems by looking at your data that essentially you have shifted your practice mostly to the Ross operation over the last 10 years, and therefore those two groups of patients that are being compared are certainly not randomized and they aren’t even concurrent, and therefore some of the differences that you have noticed may be possibly attributed to general improvements in techniques, myocardial protection, and perioperative care. In view of that and in looking at your data, have you made a firm decision to persist in this policy, or have you developed some criteria by which you choose one operation or the other according to some patient variables?
Dr Sakamoto: Actually, the Ross operation was introduced in 1996 at our institute. When we had one patient with left ventricular outflow obstruction, we formerly, before 1996, chose the Konno operation. However, we choose the Ross operation at present.
Myocardial protection and perioperative management are another things that have been changing during this decade. On the other hand, the data presented here is the long-term outcome, not the early result. Therefore, the difference between the two groups might not be affected directly by the technical improvements, although this study is not a randomized one. Our policy now is that the Ross operation is the first choice for this kind of patients and in special cases we can choose the Konno operation.
Dr J. Moll (Lodz, Poland): I was surprised that patients who had Konno operation were younger than those patients who had Ross operation. For me the Ross operation is especially good for young children. How can you explain this?
Dr Sakamoto: We had been doing the Konno operation in all cases before 1996. Afterwards we changed the strategy to the Ross operation. Actually, some young ladies who can hope for pregnancy, were good candidates for the Ross operation. Also, the patients with infectious endocarditis in aortic valve should be good candidates for Ross operation. So, from these reasons, the age of the Ross patients is a little bit higher than that of the Konno operation.
Dr Moll: And you didn’t do any Ross–Konno operations?
Dr Sakamoto: In the Ross group, 11 patients underwent the Ross-Konno operation.
Dr Moll: But you didn’t have it in this group. You divided only for Ross and Konno.
Dr Sakamoto: Ross–Konno operation is basically the Ross operation with Konno ventricular incision. The 11 patients who underwent the Ross–Konno operation do not use mechanical valves and the pulmonary autograft was implanted.
Dr R. Jonas (Washington, D.C., USA): I wanted to check that all of your Ross patients were performed as a root replacement and not as an inclusion technique and ask if you have data regarding dilation of the neoaortic root. Some very important data was published by the Children's Hospital of Philadelphia group in the Journal of the American College of Cardiology earlier this year. They had two reports actually. One was in JTCVS and one was in the cardiology journal. The report in the cardiology journal showed that dilation of the neoaortic root was of very great concern, that there was very serious dilation, and for the first time I detected that that group really has developed serious reservations about doing the Ross operation as a root replacement. So I have two questions. Did you do all your Ross procedures as a root replacement and what were the late diameters?
Dr Sakamoto: Our technique is a root replacement. In our series, there was no case of aortic root dilation. We have a couple of cases of aortic valve replacement after the Ross procedure. One patient's aortic valve was injured during the operation and he needed the aortic valve replacement in the late period. The other two patients showed aortic regurgitation due to the leaflet degeneration. We do not have any aortic root and ring dilatation cases.
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Footnotes
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Presented at the 21st Annual Meeting of the European Association for Cardio-thoracic Surgery, Geneva, Switzerland, September 16–19, 2007.
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References
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Abstract
1. Introduction
