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Eur J Cardiothorac Surg 2004;26:129-136
© 2004 Elsevier Science NL
skabskibskia
a Department of Pediatric Cardiac Surgery, University of Medical Science, ul. Szpitalna 27/33, 60-572, Pozna, Poland
b Department of Pediatric Cardiology, University of Medical Science, Pozna, Poland
c Department of Pediatric Radiology and Catheter Laboratory, University of Medical Science, Pozna, Poland
d First Department of Cardiology, University of Medical Science, Pozna, Poland
Received 2 January 2004; received in revised form 25 March 2004; accepted 9 April 2004.
* Corresponding author. Tel.: +48-61-849-1277; fax: +48-61-866-9130
e-mail: girish{at}poczta.onet.pl
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Abstract |
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 Top Abstract 1. Introduction2. Materials and methods3. Results4. DiscussionReferences |
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Key Words: Aortic valve disease • Aortic valve replacement • Aortoventriculoplasty • Follow-up
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1. Introduction |
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TopAbstract1. Introduction2. Materials and methods3. Results4. DiscussionReferences |
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Pressure overload because of narrow aortic valve leads to left ventricular hypertrophy and its dysfunction. During the surgery, the concentric hypertrophied septum is widely incised and enlarged by a patch to fit an adult size prosthesis. Patch enlargement of the left ventricular outlet tract lowers the pressure gradient across it. Little data are available about the systolic and diastolic functions after the surgery and during the long-term follow-up.
This study reports our experience in aortic valve replacement analyzed retrospectively in young and adolescent patients.
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2. Materials and methods |
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TopAbstract1. Introduction2. Materials and methods3. Results4. DiscussionReferences |
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, between 1988 and 2002. These patients were divided in two groups. Group A consisted of 26 patients (23 males and 3 females) from 5 to 18 years (13.6±3.34 years). These patients underwent simple aortic valve replacement. Among 26 patients, 8 patients had aortic valve stenosis, 8 had aortic valve insufficiency and 10 patients had complex lesion of the aortic valve. For 4 patients it was a secondary procedure. Two of them had been operated on previously for ventricular septal defect and the other two had undergone aortic valve commissurotomy (Table 1) .
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2.2. Echocardiographic data
This study is based on the echocardiographic parameters measured during the preoperative and postoperative checkups. During the follow-up these checkups were repeated every year or two. All data were taken from our hospital database.
Images of left ventricle were obtained from 2D echocardiographic examination in the parasternal long axis view and LV cavity dimensions were measured by M mode examination. LV fractional shortening and ejection fraction were calculated from these dimensions. Left ventricle flow velocities were obtained by pulsed-wave Doppler echocardiography. For the aortic valve flow velocity a five-chamber view was employed, whereas the mitral valve flow (left ventricle inflow) velocity was measured from the four-chamber view. The left ventricle–aorta pressure gradient was calculated from the aortic valve flow velocity using the modified Bernoulli equitation. The LV diastolic function was evaluated from isovolumetric relaxation time, peak diastolic filling rates and deceleration time of the early filling velocity. The early peak diastolic filling velocity (MV E), late peak velocity after atrial contraction (MV A), deceleration slope of the early filling velocity (MV DCT) and left ventricle isovolumetric relaxation time (LV IVRT) were measured.
The percentage fraction of the aortic valve index (AOVI%) was calculated as follows:
2.3. Definitions and choice of surgical technique
Classification of the aortic valve disease was made based on echo findings. Pressure gradients across the aortic valve above 30 mmHg and aortic regurgitation above II were considered significant for the nomenclature. Aortic valve with pressure gradient above 30 mmHg, and regurgitation up to II was classified as stenosis. Aortic valve with regurgitation above II and pressure gradient below 30 mmHg was classified as insufficient. Aortic valve with pressure gradient above 30 mmHg and regurgitation above II was classified as complex lesion.
Qualification for the cardiovascular procedure was also based on echo findings. Aortic stenosis with pressure gradient above 60 mmHg, aortic insufficiency IV, and complex defect with pressure gradient above 40 mmHg and regurgitation above III were qualified for the surgery. Not only the pressure gradient and aortic valve regurgitation, but also their effects on the left ventricle, were used as qualification criteria. So a patient with advanced ventricle hypertrophy was qualified for the surgery even though he had low-pressure gradient across the aortic valve.
The choice of the procedure employed for a patient depended on his age and major lesion. Adolescent patients with adult size aortic annulus were qualified for the aortic valve replacement by a mechanical prosthesis. Pediatric patients and adolescent patients with narrow aortic annulus were qualified for the Konno procedure.
2.4. Surgical technique
2.4.1. Konno procedure
The standard pediatric technique of cardiopulmonary bypass, including bicaval cannulation and moderate hypothermia, was applied. Cold cardioplegic solution of St. Thomas was induced.
The aortic valve was replaced by a mechanical prosthesis sutured to the aortic ring in a subcoronary position with continuous suture. A spindle shaped dacron patch covering the mechanical prosthesis to which it was sutured reconstructed the septal and the aortic incision. Lastly the right ventricular gap was closed with an additional dacron patch. In one patient an autologous pericardial patch was used to close the right ventricular incision. To minimize oozing through the dacron patch we originally employed preclotting of the woven dacron patch, later we used a dacron patch covered with gelatin. Lately we have employed a double layer patch (dacron+porcine pericardial) to cover the right ventriculotomy, which also covers the patch on the ascending aorta. Care was taken that at least 1/2 to 1/3 of the aortic prosthesis was covered with the native tissue.
2.4.2. Simple aortic valve replacement
Standard anesthesia, extracorporeal circulation and myocardial protection were similar as in the Konno procedure. A low transverse aortotomy in the shape of a hockey stick reaching to the non-coronary sinus was made. In cases of aortic valve insufficiency, cold cardioplegic solution was induced directly to the coronary ostium in proportion 2/3 to the left coronary ostium and 1/3 to the right coronary ostium, and repeated every 30 min. The deformed aortic valve was removed and a mechanical prosthesis was sutured in subcoronary position. The aortotomy was closed with a double whipstitch.
2.5. Follow-up
Excluding two early deaths after the Konno procedure, all the remaining patients are included in this study. After the Konno procedure, 17 patients were followed up for 80.35±49.13 months (0–173 months). After the simple aortic valve replacement 26 patients (including one late death) were followed up for 74.86±44.4 months (11–171 months). All data were collected from the hospital charts and outpatient department records.
2.6. Statistical analysis
Statistical analysis was carried out with Statistica 6.0 for Windows. Numerical variables are presented as mean±SD. Nominal data distribution was checked by the W Shapiro-Wilk test. Data not distributed normally were compared between the groups using the Mann–Whitney U test, or within the groups using the par Wilcoxon test. Analysis of patient survival was done using the Kaplan–Meier test, and predictors were analyzed with the Cox–Mantel test. A value of P<0.05 was considered significant.
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3. Results |
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TopAbstract1. Introduction2. Materials and methods3. Results4. DiscussionReferences |
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3.1.1. Hospital mortality
Two hospital deaths after the Konno procedure were noted in group B. One patient died during the operation with symptoms of stone heart syndrome. During the operation, cardiopulmonary bypass time was 244 min and aortic cross clamp time 154 min. We assume that either myocardial protection was not adequate or the dominant septal coronary artery was damaged by the septal incision. Another patient died on the seventh postoperative day. This patient had sudden bradycardia and during the resuscitation massive bleeding occurred, apparently from the pericardial patch on the right ventricular incision.
3.1.2. Morbidity
In two patients, after the Konno procedure a pacemaker had to be implanted because of complete A-V block.
Among the 26 patients undergoing simple aortic valve replacement, 16 patients (61.53%) received catecholamine, whereas after the Konno procedure all 18 patients who survived the surgery had to be treated for low cardiac output with high doses of catecholamines. Among 18 patients with low cardiac output, acute renal insufficiency was observed in one patient who had to undergo peritoneal dialysis for 12 days until the renal function was restored.
Two patients undergoing the Konno procedure had to be reoperated because of excessive drainage. In the first patient an extra suture had to be placed on the ventriculotomy patch, whereas in the second patient no surgical bleeding was found.
3.2. Late results
In contrast to the early results, most of the complications were noted in group A after simple aortic valve replacement.
3.2.1. Late mortality
One patient died a year after the surgery. No autopsy was performed, so the cause of death is unknown.
3.2.2. Late morbidity
In one patient 9 months after simple aortic valve replacement, septic fever was observed. Blood culture showed methicillin-resistant Staphylococcus. In an echocardiography checkup, vegetation on the mechanical prosthesis causing aortic valve regurgitation of III was noted. Antibiotic therapy failed, so the patient was scheduled for the Ross procedure, and 11 months after the primary surgery the mechanical prosthesis was replaced with a pulmonic autograft [9].
3.3. Aortic valve index
In group A with larger patients, after simple aortic valve replacement (Table 1) 42% of them received mechanical prosthesis of small size (19 and 21 mm), whereas in group B with smaller patients only 36.8% of them received prosthesis of small size (Table 1). So the AOVI% after AVR dropped significantly (P<0.01) from 110±21 to 98±11% and a further downward tendency was observed in the following years. After the Konno procedure AOVI% rose significantly (P<0.001) from 82±16 to 114±11%, and during the following years, as the patients grew, it slowly dropped (P<0.05) to 95±18% (Fig. 1).
3.4. Systolic function
In both groups, after the surgery improvement of the systolic function was noted. A significant drop (P<0.01) in the pressure gradient from 49.4±27 to 21.26±15 mmHg across the aortic valve was noted after the valve replacement in group A (Fig. 2). Fractional shortening and ejection fraction of the left ventricle also became normalized (P<0.05) after the surgery in this group (Figs. 3 and 4). During the following years, with further lowering of the aortic valve index, the pressure gradient across the aortic valve increased and so did the value of fractional shortening and ejection fraction of the left ventricle. In group B the pressure gradient across the aortic valve decreased significantly (P<0.001) after the Konno procedure, from 80.45±21 to 11.17±5 mmHg (Fig. 2). Hyperkinetic function of the left ventricle also became normalized (P<0.01) (Fig. 3). At the end of our observation, especially in patients with small valves (19 and 21 mm) we observed hemodynamically significant pressure gradient across the aortic valve (Fig. 2). Fractional shortening and ejection fraction of the left ventricle were also elevated, though still within the norms (Fig. 3). After 60 months only 22% of patients in group A and 75% in group B still had pressure gradients below 30 mmHg (Fig. 7).
3.5. Diastolic function
Within both groups and between the two groups no significant differences were observed between the left ventricle inflow parameters over the whole period of observation (Figs. 4–6). Nevertheless in group A, at the end of our observation, MV DCT and LV IVRT were elevated above the norms (P non-significant). Similarly in group B, MV DCT before the surgery was below the norms and 6 years after the surgery was above the norms (P non-significant) (Figs. 5 and 6).
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4. Discussion |
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TopAbstract1. Introduction2. Materials and methods3. Results4. DiscussionReferences |
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The degree of improvement in left ventricle structure and function after aortic valve replacement depends on the extent of hypertrophy at the time of operation, coexisting disease, extent of left ventricle intraoperative damage and residual or recurrent stenosis or incompetence of the valve replacement device [11]. As all the patients included in this study were children and adolescents, the left ventricle damage was not so extensive before the surgery as in the adult population. The only permanent damage during the surgery was the interventricular septal incision during the Konno procedure in group B which could compromise the left ventricle function. During the postoperative period it was confirmed by low cardiac output in all patients requiring inotropic support within this group. In one patient it even resulted in acute renal insufficiency. Another damaging result of interventricular septal incision is complete A-V block. This was noticed in two patients (10.52%) in this study and pacemakers had to be implanted in these patients. According to other authors this complication is rare and ranges from 2 to 7% [5,6,11]. During the septal incision the surgeon should try to aim toward the left side of the septum to avoid damaging the conducting tissue. Early mortality after the Konno procedure in this study (10.52%) is well within the range (5–15%) reported elsewhere [2,5,6].
In group A, considering the patients' age and their BSA, one should expect that the size of mechanical prosthesis implanted would be larger, whereas only 48% of the population received large size (size 23 mm and above) prosthesis (Table 1). As a result, after the surgery a significant drop in AOVI% was noticed, and this further declined due to somatic growth of the patients in the following years. In the postoperative period residual pressure gradient between the left ventricle and the ascending aorta became significant in this group during the following years. LVSF and LVEF were also within the upper limit throughout the observation period.
In group B, with smaller patients having low BSA, in almost 54% of the population mechanical prosthesis of larger size were implanted (Table 1). Anterior augmentation of the aortic valve as proposed by Konno and Rastan [1,2] completely removed left ventricular outlet tract obstruction. As a result a spectacular drop in the pressure gradient between the left ventricle and ascending aorta was noticed. Left ventricle fractional shortening and ejection fraction also became normalized [12]. The only drawbacks related to the very young patients in whom small prosthesis (size 19 and 21) were implanted. In these patients low AOVI% resulted in the appearance of pressure gradients across the aortic prosthesis 5 years after the surgery. So after 60 months only 22% of patients in group A, as compared to 75% in group B, still had pressure gradient below 30 mmHg (Fig. 7).
Pressure gradient after mechanical prosthesis implantation is present in virtually all patients. Its magnitude depends on the characteristics of the prosthesis, the size of the device relative to the size of the patient, the cardiac output and abnormal developments in and around the replacement device [11]. Nonetheless all mechanical prosthesis larger than 21 mm size can provide satisfactory performance in most adults. Implanting a 19 mm aortic valve is acceptable only in patients with BSA not greater than 1.7 m2 [13]. Even low (10 mmHg) resting gradients associated with prosthetic valves (especially those of small size) increase during periods of increased cardiac output [14]. So while choosing the type and size of prosthesis for the pediatric patient, the surgeon should take into consideration the patient's potential growth and the average BSA for the given population.
Hypertrophied left ventricle, because of its decreased compliance, has an adverse influence on its diastolic function. Murakami et al. [15] demonstrated that left ventricle filling might vary depending on the degree of LV hypertrophy and systolic ejection performance in patients with aortic stenosis. Villari et al. state that relaxation abnormalities and passive diastolic myocardial stiffness precede alterations in myocardial contractility. Assessment of peak filling rates is not helpful for detecting diastolic dysfunction in patients with aortic valve disease [16]. In our study also early and late peak filling velocities of left ventricle showed no variation between the two groups (P non-significant). They were within the norms throughout the observation period (Fig. 4). Otto et al. [17] also state that no difference in MV E, MV A, or MV E/A was found in patients with AS and age-matched normal subjects. Fifer et al. [18], studying 16 pediatric patients and 25 adults with AS, showed larger deterioration of the LV diastolic function in adults than in children and attributed it to the magnitude of LV hypertrophy.
Most of the patients in group A with high values of MV DCT and LV IVRT had diastolic dysfunction with abnormal relaxation and reduced distensibility. Opening of the mitral valve in these patients is delayed, because the pressure fall in the hypertrophied left ventricle is slower, hence LV IVRT is elongated. During the diastolic phase high pressure in the left ventricle with decreased compliance increases the early filling time, especially its deceleration slope [17,19]. These values were around the upper limit throughout the observation period, but during the last 2 years of the observation they even exceed the upper normal limits (P, non-significant) (Figs. 5 and 6).
In group B before and during the postoperative period patients with low values of MV DCT (below 120 ms) and normal values of LV IVRT had diastolic dysfunction with pseudonormal filling patterns [20]. In these patients elevated atrial pressure decreases the atrial-left ventricle pressure gradient and shortens the early filling time, in particular its deceleration slope [17,19–21]. In the following years these parameters became normalized (P, non-significant). By the end of our observation we noticed high values of MV DCT and LV IVRT signifying LV diastolic dysfunction with abnormal relaxation (P, non-significant) (Figs. 5 and 6). This dysfunction was observed in patients with small prosthesis.
In summary, we conclude that improvement of the systolic function after the surgery was noted in both groups. The residual pressure gradient noted in group A became significant (above 30 mmHg) 2 years after the surgery. In group B significant recurrent pressure gradient was noted 5 years after the surgery. As regards the diastolic function, no significant difference was noted between these two groups. As far as septal incision is concerned, it may have some transient effects on the left ventricle function in the postoperative period, but no permanent sequelae were observed in the long-term follow-up.
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References |
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TopAbstract1. Introduction2. Materials and methods3. Results4. DiscussionReferences |
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