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Ann Thorac Surg 2008;85:604-610. doi:10.1016/j.athoracsur.2007.10.035
© 2008 The Society of Thoracic Surgeons
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Right arrow Valve disease

Original Articles: Cardiovascular

Outcome After Mechanical Aortic Valve Replacement in Children and Young Adults

Raoul Arnold, MDa,1, Julia Ley-Zaporozhan, MDb,1, Sebastian Ley, MDc, Tsvetomir Loukanov, MDd, Christian Sebening, MDd, Johann-Baptist Kleber, cand.med.e, Björn Goebel, MDf, Siegfried Hagl, MDd, Matthias Karck, MDd, Matthias Gorenflo, MDe,*

a Department of Pediatric Cardiology, University Medical Centre, Freiburg, Germany
b Department of Radiology, German Cancer Research Center, Heidelberg, Germany
c Pediatric Radiology, University Hospital Heidelberg, Heidelberg, Germany
d Department of Cardiac Surgery, University Medical Center, Heidelberg, Germany
e Department of Pediatric Cardiology, University Medical Center, Heidelberg, Germany
f First Department of Medicine, University Hospital Jena, Jena, Germany

Accepted for publication October 5, 2007.

* Address correspondence to Dr Gorenflo, Department of Pediatric Cardiology, University Medical Center, INF 153, Heidelberg, D-69120, Germany (Email: matthias.gorenflo{at}med.uni-heidelberg.de).


   Abstract
Top
 Abstract
Introduction
 Patients and Methods
 Results
 Comment
 Footnotes
 Acknowledgments
 References
 
Background: We asked whether aortic valve replacement using a mechanical prosthesis would allow normalization of left ventricular function and structure in children and young adults.

Methods: We performed a clinical follow-up examination in 30 patients with aortic valve replacement at 25 years of age or younger, including conventional and tissue Doppler echocardiography and magnetic resonance imaging.

Results: Aortic valve replacement was performed at the median age of 14.3 years (range, 7.6 to 24.3 years) using a mechanical prosthesis (St. Jude Medical; median diameter, 23 mm; range, 17 to 27 mm). Indications were severe aortic stenosis in 6 of 30 patients, aortic regurgitation in 20 of 30 patients, or a combination of aortic stenosis and regurgitation (4 of 30 patients). Aortic valve replacement was a reoperation in 12 of 30 patients who primarily underwent aortic valvotomy at a median of 7.1 years (range, 1.0 to 11.3 years). In-hospital mortality was 0%. Follow-up was a median of 6 years (range, 1.2 to 14.5 years). Twenty-nine of 30 patients were in New York Heart Association functional class I without thromboembolic complications, cerebrovascular accidents, or major bleeding on oral anticoagulation. Left ventricular dilatation before aortic valve replacement was present in 20 of 30 patients but normalized in all but 4 patients on follow-up. Most patients showed a normal end-diastolic volume on magnetic resonance imaging, and 23 of 26 patients showed a normal left ventricular ejection fraction (median, 0.53; range, 0.33 to 0.75). Peak systolic strain of the left ventricular myocardium was a median of –13.3% (range, –0.5% to –31%), and was normal in 28 of 30 patients.

Conclusions: Aortic valve replacement in children and young adults offers a good treatment option and may lead to normalization of left ventricular size and function in most patients.


   Introduction
Top
 Abstract
 Introduction
Patients and Methods
 Results
 Comment
 Footnotes
 Acknowledgments
 References
 
Mechanical aortic valve replacement (AVR) represents one of several treatment options currently available for children presenting with severe aortic valve stenosis or aortic regurgitation not suitable to valve-sparing surgical procedures. Previous studies report a favorable outcome with low mortality and morbidity in children with mechanical AVR [1, 2]. However, AVR with mechanical prosthesis carries the potential risk of thromboembolism and the need for lifelong anticoagulation with the risk of hemorrhage. The fixed prosthesis diameter in the growing child may lead to a valve re-replacement later in life [3].

Little is known about the long-term effect of mechanical AVR on left ventricular geometry and function in children and adolescents, especially in the context of left ventricular (LV) dilatation and hypertrophy. In this single-institution observational study we report the long-term outcome in children using conventional echocardiography, two-dimensional strain echocardiography (2D-strain echo), and magnetic resonance tomography (MRI). We asked whether LV dilatation would normalize after AVR in children and adolescents.


   Patients and Methods
Top
 Abstract
 Introduction
 Patients and Methods
Results
 Comment
 Footnotes
 Acknowledgments
 References
 
Patients
We reviewed the database of our institution for patients who underwent surgery for AVR as a result of congenital valve disease at the age of 25 years or younger in the period between January 1992 and December 2005. Patients presenting with LV outflow tract obstruction requiring an aortoventriculoplasty (Konno procedure) were excluded [4]. Of 40 patients who fulfilled these criteria, 30 agreed to participate in this study and presented for reexamination. Four of these 40 patients reported to be in a good condition but declined to participate, and 6 patients discharged from our unit after successful AVR were living abroad and lost to follow-up. Informed consent was obtained from all patients participating in this study. The study protocol was approved by the local ethical committee (number L-50-2006).

A follow-up visit was performed, and the following data were obtained: (1) clinical examination and assessment of the functional status of the patients according to the New York Heart Association (NYHA) classification [5], (2) echocardiography including two-dimensional conventional Doppler and 2D-strain echo, (3) MRI of the left ventricle, and (4) the presence or absence of thromboembolic or bleeding complications such as gastrointestinal, cerebral, or posttraumatic bleeding.

Cardiac Catheterization Before Aortic Valve Replacement
All patients underwent cardiac catheterization and biplane angiography before AVR with a Philips Integris BH 3000 machine (Philips Nederland B.V., Eindhoven, The Netherlands). Diagnostic quality was achieved in all cases. Digital and film-stored catheterization and hemodynamic data were reviewed by one reader (M.G.) blinded to echocardiography and MRI findings. Size of the left ventricle was evaluated as "normal" or "dilated" using angiographic criteria [6]. Additionally, peak-to-peak systolic gradient across the native aortic valve and the degree of aortic regurgitation were assessed.

Surgical Technique
Cardiopulmonary bypass with moderate systemic hypothermia (28° to 32°C) was used in all patients. As a standard technique, the aortic valve annulus was incised and a careful subvalvular myectomy was performed when necessary. A mechanical prosthesis (St. Jude Medical, St. Paul, MN) was implanted in all patients in a subcoronary and supraannular position. Transesophageal echocardiography was performed before protamine administration and removal of cannulas to confirm adequate valve function and complete air evacuation. The median cardiopulmonary bypass time at surgery was 88 minutes (range, 65 to 245 minutes), and the median cross-clamp time was 58 minutes (range, 33 to 172 minutes). Anticoagulation was performed with phenprocoumon in all cases with the aim to achieve an international normalized ratio between 2.5 and 3.5.

Echocardiography
Image Acquisition
Echocardiographic data could be obtained in all patients using a General Electric Vivid 7 system (GE Vingmed Ultrasound, Horten, Norway) equipped with a M3S Octave phased-array transducer (transducer frequency, 2.0/4.3 MHz). Echocardiographic studies included M-mode and two-dimensional studies of the left heart and the aorta. Color, pulsed-wave, and continuous-wave Doppler studies were performed over the mitral and aortic valves and the LV outflow tract. Values were related to data obtained in a large series of patients with known well-functioning St. Jude Medical aortic valve prostheses [7].

A 2D-strain echo was performed in the same session. For image analysis, cine loops of at least three cardiac cycles were acquired from an apical four-chamber view and parasternal short axis.

Image Processing and Quantitative Analysis
Digitally stored data were reviewed by two readers (R.A., B.G.), blinded to MRI findings. We used General Electric EchoPAC software for M-mode, two-dimensional, and conventional Doppler studies and for 2D-strain echo analysis.

M-Mode, Two-Dimensional, and Conventional Doppler Echocardiography
The LV volumes and ejection fraction (EF) were calculated by the method of Simpson from biplane imaging. Left ventricular mass was calculated from M-mode studies using the Devereux method [8].

Doppler studies included maximum and mean velocity across the aortic valve and the LV outflow tract. In addition, mitral valve peak flow velocity in the early diastole and peak velocity at atrial contraction were measured. The ratio between them was additionally calculated [9].

Two-Dimensional Strain Echocardiography
The 2D-strain echo analysis software on the EchoPAC program was used using unique ultrasound patterns in each frame [10]. These individual patterns were tracked for variable periods and were then continually replaced to track further in time. The displacement of each pattern with time was used to calculate velocity, and this velocity is used to derive strain rate and strain [11].

The following variables were analyzed for the longitudinal function (measured in the apical four-chamber view) and the radial function (measured in the parasternal short axis): peak systolic strain, peak systolic strain rate, peak early diastolic strain rate, and peak late diastolic strain rate. All variables were averaged for three cardiac cycles, and all values were averaged to yield a mean value. Signals that did not have a significant peak in systole and two distinct peaks in diastole were labeled as uninterpretable.

Magnetic Resonance Imaging
Image Acquisition
Studies were performed on a commercial 1.5 -T whole-body magnetic resonance system (Magnetom Avanto; Siemens Medical Systems, Erlangen, Germany) with a slew rate of 30 mT/m and 125 T/m per second. The electrocardiographic gating unit of the scanner was used for triggering during the cardiac measurements. For magnetic resonance signal detection one body array coil (anterior) and the two spine array elements (posterior) were used. No intravenous contrast media was applied. The magnetic resonance protocol contained sequences to quantify LV volume, the EF, and myocardial mass. Data were compared with values obtained in healthy control subjects using these techniques [12, 13].

Image Processing and Quantitative Analysis
The volume of the left ventricle was evaluated with a dedicated software application (Argus; Siemens Medical Solutions) following the standard evaluation procedures [14, 15]. The end-systolic and end-diastolic volumes and stroke volume were obtained. The EF was calculated as stroke volume divided by end-diastolic volume. For calculation of the LV mass the density of the myocardium was assumed to be 1.05 g/cm3 [16, 17].

Regional wall motion abnormalities were assessed visually by two readers (J.L., S.L). Evaluation of MRI data was done blinded to all other examination results.

Statistics
Data are presented as median and range. Descriptive statistics was used to analyze patient demographic data and variables obtained by cardiac catheterization, echocardiography, and MRI. Linear regression analysis was performed to study the correlation between echocardiographic and MRI data. Results of MRI and echocardiography were compared using the Spearman rank order correlation test. A probability value of 0.05 or less was considered significant.


   Results
Top
 Abstract
 Introduction
 Patients and Methods
 Results
Comment
 Footnotes
 Acknowledgments
 References
 
Patients
At birth 5 of 30 presented with isolated aortic regurgitation without signs of preceding endocarditis. None of these 5 patients underwent previous surgical or interventional valvuloplasty. Seven of 30 patients presented with both aortic stenosis and regurgitation. Eighteen of 30 had isolated aortic stenosis of whom 12 primarily underwent aortic valvotomy at 7.1 years (range, 1.0 to 11.3 years). The interval between the valvotomy and the AVR was 5.0 years (range, 3.3 to 15 years).

The morphology of the aortic valve was assessed at surgery. Sixteen of 30 patients were found to have dysplastic, primarily bicuspid aortic valves. The remaining 14 patients presented with dysplastic tricuspid aortic valves.

Associated congenital cardiac defects were found in 4 of 30 patients. In 2 patients an additional ventricular septal defect was closed at the operation for AVR. In this series the 2 patients with the additional ventricular septal defect did not present with a subaortic ventricular septal defect. Aortic regurgitation was not related to the ventricular septal defect in these patients. In 2 patients coarctation repair was performed previously. In-hospital mortality and late mortality in these 40 patients after AVR was 0%.

Echocardiography Before Aortic Valve Replacement
Left ventricular systolic function as assessed by the determination of the shortening fraction was within normal ranges in most patients (shortening fraction, 37%; range, 28% to 49%). Measurements of left ventricular end-diastolic diameter were available in 22 of 30 patients (median, 37 mm; range, 26 to 56 mm). The LV end-diastolic diameter was found to be normal in 15 of 22 patients. In 7 of 22 patients LV end-diastolic diameter was increased (>55 mm).

Cardiac Catheterization Data Before Aortic Valve Replacement
Severe aortic stenosis was present in 6 of 30 patients: the peak-to-peak gradient was 55 mm Hg (range, 40 to 80 mm Hg; Table 1). Significant aortic regurgitation was present in 20 of 30 patients and a combination of aortic stenosis and regurgitation in 4 of 30 patients (Table 1). Twenty of 30 patients (ie, the patients with significant aortic regurgitation) showed dilatation of the left ventricle.


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  		Table 1 Demographic and Clinical Data at Operation for Aortic Valve Replacement a
 
Timing of Aortic Valve Replacement
Demographic and clinical data at operation for AVR are given in Table 1. At the time of AVR patients were 14.3 years old (range, 7.6 to 24.3 years). The size of the implanted prosthesis was 23 mm (range, 17 to 27 mm; Fig 1). Few children required AVR with a prosthesis less than 21 mm (Fig 1). The individual aortic valve annulus was measured at surgery using calibrated Hegar-probes. The Z-scores of these and other measurements are given in Table 2. Prostheses were chosen according to the measured size of the aortic annulus. Fourteen of 30 patients received a St. Jude Medical–Hemodynamic Plus prosthesis.


Figure 1
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  		Fig 1. Size of implanted St. Jude Medical (SJM) prostheses and age at aortic valve replacement (AVR).

 

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  		Table 2 Calculated Z-Scores for Left Ventricular Mass Derived From Magnetic Resonance Imaging and Left Ventricular End-Diastolic Diameter Before and After Aortic Valve Replacement (Echocardiographic Data)
 
Clinical Examination at Follow-Up: Prosthetic Valve-Related Morbidity
At follow-up, the patients were 21 years old (range, 13 to 31 years). The median follow-up period was 5.9 years (range, 1.2 to 14.5 years). The follow-up period with respect to the implanted sizes of prosthesis is depicted in Figure 2. On clinical examination, 29 of 30 patients were in NYHA functional class I; 1 patient presenting with acute valve thrombosis at the time of examination was in NYHA class III at presentation. Replacement of mechanical prosthesis was necessary in this patient only and led to complete recovery (see details below).


Figure 2
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  		Fig 2. Follow-up period with respect to implanted sizes of prostheses. (AVR = aortic valve replacement; SJM = St. Jude Medical.)

 
Two patients required implantation of a pacemaker as a result of complete heart block after AVR. These patients did not undergo additional ventricular septal defect closure. There were no hemorrhagic events such as gastrointestinal or cerebral bleeding observed during follow-up.

One 32-year-old woman with a known heterozygote prothrombin mutation underwent AVR at the age of 15 years for severe aortic valve regurgitation. She was anticoagulated with phenprocoumon. Seventeen years later she intended to become pregnant, and phenprocoumon was replaced by low-molecular-weight heparin (Nadroparin) at another clinic. Shortly thereafter she presented at our center with valve thrombosis and dysfunction and was in NYHA functional class III. The 21-mm St. Jude Medical prosthesis was replaced using a St. Jude Medical prosthesis of the same size. Postoperative complete atrioventricular block ensued, and a permanent dual-chamber pacemaker was implanted. After all procedures she recovered and is now in NYHA class I.

Echocardiography
Echocardiography at follow-up was performed in all patients. Echocardiographic data are summarized in Table 3. Fractional shortening of the left ventricle was normal in 26 of 30 patients. Left ventricular EF was 0.55 (range, 0.24 to 0.67). Left ventricular end-diastolic diameter was found to be normal in 26 of 30 patients, whereas 4 of 30 patients showed LV dilatation on follow-up after AVR, 2 of them showing LV dilatation before surgery.


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  		Table 3 Echocardiographic Findings in 30 Patients After Aortic Valve Replacement
 
The mean systolic gradient across the aortic valve prosthesis was 14 mm Hg (range, 5 to 29 mm Hg) as calculated from the continuous-wave Doppler measurements (Table 3). In children after AVR using prostheses of 17 and 19 mm diameter, the mean systolic gradient did not exceed 30 mm Hg (Fig 3).


Figure 3
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  		Fig 3. Size of implanted prostheses versus mean systolic gradient at follow-up, determined by continuous-wave Doppler echocardiography (cw-Doppler).

 
Tissue Doppler examination revealed that LV contractility expressed by strain and strain rate was normal in 28 of 30 patients and decreased in 2 of 30 patients compared with values obtained in healthy control subjects [10]. One patient (clinically in NYHA class I) presented with extreme LV asynchronicity accompanied by left bundle-branch block. He was found to have pathologic values in all examined tissue Doppler variables.

Magnetic Resonance Imaging Data
Magnetic resonance imaging scans could be performed in 25 of 30 patients. In 2 patients MRI could not be performed because of an implanted pacemaker. Three patients declined to participate in this examination. Left ventricular mass was normal in 23 of 25 patients (Tables 2, 4).Go One patient with severe aortic regurgitation was found to have a reduced LV myocardial mass (34.3 g/m2) at follow-up. Another patient presenting with aortic valve stenosis and regurgitation before AVR was found have an increased LV myocardial mass (83.3 g/m2) at follow-up. A good correlation (Spearman rank order correlation coefficient = 0.746; p < 0.01) was found between the LV mass determined by echocardiography and MRI and was confirmed by linear regression analysis (LV mass [MRI] = 66.054 + [0.851 x LV mass echo]; R = 0.775; p < 0.001).


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  		Table 4 Magnetic Resonance Imaging Findings in 25 of 30 Patients After Aortic Valve Replacement Compared With Normal Values
 
Twenty-two of 25 patients showed a normal end-diastolic volume (Table 4, Fig 4). A slight reduction in LV end-diastolic volume was observed in 4 of 25 patients presenting with LV muscle mass in the upper range of normal on follow-up.


Figure 4
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  		Fig 4. Left ventricular dilatation in a patient with aortic regurgitation (A) on angiography and normalization of left ventricular size in the same patient after aortic valve replacement as demonstrated by magnetic resonance imaging (B).

 
Twenty-three of 26 patients showed a normal LV EF (Table 4). Three patients showed a reduced LV EF. There was a high correlation (Spearman rank order correlation coefficient = 0.6; p < 0.01) between the two modalities (echocardiography and MRI) for determination of the LV EF, which was confirmed on linear regression analysis (LV EF [MRI] = 13.188 + (0.737 x LV EF echo; R = 0.693; p < 0.001).

The visually assessed global LV function was good in 24 of 25 patients; 7 of 24 patients showed mild septal hypokinesia. One patient showed a reduced systolic function combined with a septal hypokinesia.


   Comment
Top
 Abstract
 Introduction
 Patients and Methods
 Results
 Comment
Footnotes
 Acknowledgments
 References
 
This study focussed on left ventricular morphology and function in children and young adults after AVR using mechanical prosthesis. Mid-term follow-up in 30 patients after AVR showed good functional and morphologic results determined by echocardiography and MRI. In addition most patients show a good functional status. Complications were rare provided that anticoagulation was performed adequately.

As shown by other authors, survival after this procedure is high (94% to 96%) [2, 18] and freedom of reoperation is better compared with alternative procedures [19]. The use of a mechanical prosthesis, however, is often criticized because of possible complications, inconvenience from anticoagulation [20], and need for reoperation because of outgrowth.

Previous studies have addressed the survival rate and morbidity after AVR [2, 21, 22]. The development of the LV structure and function is extremely important for the long-term result and was therefore the primary goal of our investigation. Using echocardiographic data alone, Tafreshi and coworkers [23] have demonstrated that the presence of severe LV dilatation and reduced LV EF both are predictors of persistent LV dilatation after AVR in children. In contrast to Tafreshi and coworkers, we did not encounter preoperative LV dilatation exceeding 4 standard deviations of the normal. In our study no severe postoperative dilation occurred. We can thus assume that AVR should not be postponed until severe LV dilatation has developed. In this series, 20 of 30 patients showed dilatation of the left ventricle before AVR, but LV function was still preserved in most of our patients before AVR. Both MRI and echocardiography demonstrated that LV dilatation disappeared in most of our patients at follow-up. Our data, therefore, do not contradict the findings of Tafreshi and coworkers [23]. Regional wall motion abnormalities were rare in our series and limited to the septal region. Overall wall motion abnormalities were mild.

All but 1 patient were in NYHA class I, and did not show exercise restriction. The single patient being in NYHA class III presented with acute valve thrombosis as a result of inappropriate anticoagulation.

Development of LV dimensions and function as well as the clinical status after AVR were favorable in our study group. To assess load-independent myocardial function 2D-strain echo was performed. Two-dimensional strain echocardiography is a novel method for real-time quantitative echocardiographic assessment of myocardial function [10]. Lately strain echocardiography proved feasible to detect early subclinical myocardial abnormalities in asymptomatic young patients with aortic regurgitation of severe degree, despite the presence of a normal EF [24]. Systolic and diastolic values of our patients were within the known normal ranges in 90% of the patients investigated. Of note, low values were found in the same patients who had pathologic findings on conventional echocardiography and MRI. In 1 patient only, presenting with left bundle-branch block and contractive asynchronicity, values were diminished, potentially as a result of the fact that electric abnormality might lead to unreliable measurements. Overall, 2D-strain echo data support our findings from conventional echocardiography and MRI. High correlations between echocardiography and MRI were found in this study for LV mass and LV EF. This finding underlines the capability of MRI in the assessment of the left ventricle after mechanical aortic valve prosthesis.

Potential complications after implantation of a mechanical valve are thrombosis, hemorrhage, cerebral embolism, ventricular arrhythmias, ventricular failure, and endocarditis [21]. In our series complications were rare. In fact the only patient presenting with valve thrombosis was treated with low-molecular-weight heparin despite known prothrombin mutation. Additionally, current observations show that anticoagulation with subcutaneous low-molecular-weight heparin does not prevent valve clotting sufficiently during pregnancy [25]. With adequate self-management of anticoagulation, the complication rate for thrombosis, hemorrhage, and cerebral embolism has improved [26].

The median follow-up period after AVR in this study (5.9 years) represents a limitation with respect to potential reoperations in the future: At present none of the patients needed reoperation for valve outgrowth. The single patient with a 17-mm St. Jude Medical prosthesis being implanted at the age of 7 thus far was found to be free from valve dysfunction at follow-up at the age of 13 years. However, with further somatic growth he might be expected to need a reoperation. We did not perform standardized exercise testing to assess the global functional status of the patients. However, all patients reported a normal physical activity at follow-up.

We did not attempt to compare our procedure and policy for AVR in children with alternative concepts such as the Ross procedure or homograft repair. Therefore we cannot judge which of the methods will ultimately lead to better outcome and fewer complications. However, concerns regarding potential reoperation for autograft dysfunction and replacement of right ventricular–to–pulmonary artery conduits are a matter of continuing debate [27–29].

In summary, our data demonstrate that AVR in children and young adults can be performed safely and with low morbidity using oral anticoagulation. Functional outcome in the long-term is favorable. Regression of LV dilatation in children with severe aortic regurgitation can be observed on echocardiography and MRI after timely AVR [30].


   Acknowledgments
Top
 Abstract
 Introduction
 Patients and Methods
 Results
 Comment
 Footnotes
 Acknowledgments
References
 
We are grateful to Angelika Jung, Brigitte Bernstorff, and Waltraud Kansteiner for perfect technical assistance. We thank Susanne Yubai for performing the magnetic resonance examinations.


   Footnotes
Top
 Abstract
 Introduction
 Patients and Methods
 Results
 Comment
 Footnotes
Acknowledgments
 References
 
1 Raoul Arnold and Julia Ley-Zaporozhan equally contributed to this work and are both first authors of this paper. Back


   References
Top
 Abstract
 Introduction
 Patients and Methods
 Results
 Comment
 Footnotes
 Acknowledgments
 References
 

  1. Ibrahim M, Cleland J, O’Kane H, Gladstone D, Mullholland C, Craig B. St. Jude Medical prosthesis in children J Thorac Cardiovasc Surg 1994;108:52-56.[Abstract/Free Full Text]
  2. Shanmugam G, MacArthur K, Pollock J. Mechanical aortic valve replacement: long-term outcomes in children J Heart Valve Dis 2005;14:166-171.[Medline]
  3. Kanter KR, Kirshbom PM, Kogon BE. Redo aortic valve replacement in children Ann Thorac Surg 2006;82:1594-1597.[Abstract/Free Full Text]
  4. Ullmann MV, Gorenflo M, Sebening C, et al. Long-term results after reconstruction of the left ventricular outflow tract by aortoventriculoplasty Ann Thorac Surg 2003;75:143-146.[Abstract/Free Full Text]
  5. Fox AC, Devereaux RB, The Criteria Committee of the New York Heart Association Nomenclature and Criteria for Diagnosis of Diseases of the Heart and Great Vessels9th ed.. Boston: Little, Brown & Co; 1994.
  6. Dodge HT, Sandler H, Ballew DW, Lord Jr JD. The use of biplane angiocardiography for the measurement of left ventricular volume in man Am Heart J 1960;60:762-776.[Medline]
  7. Perin EC, Jin BS, de Castro CM, Ferguson JJ, Hall RJ. Doppler echocardiography in 180 normally functioning St. Jude Medical aortic valve prostheses: early and late postoperative assessments Chest 1991;100:988-990.[Medline]
  8. Devereux RB, Reichek N. Echocardiographic determination of left ventricular mass in man: anatomic validation of the method Circulation 1977;55:613-618.[Abstract/Free Full Text]
  9. Appleton CP, Jensen JL, Hatle LK, Oh JK. Doppler evaluation of left and right ventricular diastolic function: a technical guide for obtaining optimal flow velocity recordings J Am Soc Echocardiogr 1997;10:271-292.[Medline]
  10. Leitman M, Lysyansky P, Sidenko S, et al. Two-dimensional strain-a novel software for real-time quantitative echocardiographic assessment of myocardial function J Am Soc Echocardiogr 2004;17:1021-1029.[Medline]
  11. D’Hooge J, Heimdal A, Jamal F, et al. Regional strain and strain rate measurements by cardiac ultrasound: principles, implementation and limitations Eur J Echocardiogr 2000;1:154-170.[Abstract/Free Full Text]
  12. Alfakih K, Plein S, Thiele H, Jones T, Ridgway JP, Sivananthan MU. Normal human left and right ventricular dimensions for MRI as assessed by turbo gradient echo and steady-state free precession imaging sequences J Magn Reson Imaging 2003;17:323-329.[Medline]
  13. Haimerl J, Freitag-Krikovic A, Rauch A, Sauer E. Quantification of aortic valve area and left ventricular muscle mass in healthy subjects and patients with symptomatic aortic valve stenosis by MRI Z Kardiol 2005;94:173-181.[Medline]
  14. Rominger MB, Kluge A, Bachmann GF. [Biventricular MR volumetric analysis and MR flow quantification in the ascending aorta and pulmonary trunk for quantification of valvular regurgitation] Rofo Fortschr Geb Rontgenstr Neuen Bildgeb Verfahr 2004;176:342-349.[Medline]
  15. Ley S, Eichhorn J, Ley-Zaporozhan J, et al. Evaluation of aortic regurgitation in congenital heart disease: value of MR imaging in comparison to echocardiography Pediatr Radiol 2007;37:426-436.[Medline]
  16. Katz J, Milliken MC, Stray-Gundersen J, et al. Estimation of human myocardial mass with MR imaging Radiology 1988;169:495-498.[Abstract/Free Full Text]
  17. Semelka R, Tomei E, Wagner S, et al. Normal left ventricular dimensions and function: interstudy reproducibility of measurements with cine MR imaging Radiology 1990;174:763-768.[Abstract/Free Full Text]
  18. Sachweh JS, Tiete AR, Muhler EG, et al. Mechanical aortic and mitral valve replacement in infants and children Thorac Cardiovasc Surg 2007;55:156-162.[Medline]
  19. Kilian E, Oberhoffer M, Gulbins H, Uhlig A, Kreuzer E, Reichart B. Ten years’ experience in aortic valve replacement with homografts in 389 cases J Heart Valve Dis 2004;13:554-559.[Medline]
  20. Al-Halees Z, Pieters F, Qadoura F, Shahid M, Al-Amri M, Al-Fadley F. The Ross procedure is the procedure of choice for congenital aortic valve disease J Thorac Cardiovasc Surg 2002;123:437-442.[Abstract/Free Full Text]
  21. Astor BC, Kaczmarek RG, Hefflin B, Daley WR. Mortality after aortic valve replacement: results from a nationally representative database Ann Thorac Surg 2000;70:1939-1945.[Abstract/Free Full Text]
  22. Karamlou T, Jang K, Williams WG, et al. Outcomes and associated risk factors for aortic valve replacement in 160 children: a competing-risks analysis Circulation 2005;112:3462-3469.[Abstract/Free Full Text]
  23. Tafreshi RI, Shahmohammadi A, Davari PN. Predictors of left ventricular performance after valve replacement in children and adolescents with chronic aortic regurgitation Pediatr Cardiol 2005;26:331-337.[Medline]
  24. Di Salvo G, Pacileo G, Verrengia M, et al. Early myocardial abnormalities in asymptomatic patients with severe isolated congenital aortic regurgitation: an ultrasound tissue characterization and strain rate study J Am Soc Echocardiogr 2005;18:122-127.[Medline]
  25. Descarries LM, Leduc L, Khairy P, Mercier LA. Low-molecular-weight heparin in pregnant women with prosthetic heart valves J Heart Valve Dis 2006;15:679-685.[Medline]
  26. Koertke H, Zittermann A, Wagner O, Koerfer R. Self-management of oral anticoagulation therapy improves long-term survival in patients with mechanical heart valve replacement Ann Thorac Surg 2007;83:24-29.[Abstract/Free Full Text]
  27. Hazekamp MG, Grotenhuis HB, Schoof PH, Rijlaarsdam ME, Ottenkamp J, Dion RA. Results of the Ross operation in a pediatric population Eur J Cardiothorac Surg 2005;27:975-979.[Abstract/Free Full Text]
  28. Luciani GB, Favaro A, Casali G, Santini F, Mazzucco A. Ross operation in the young: a ten-year experience Ann Thorac Surg 2005;80:2271-2277.[Abstract/Free Full Text]
  29. Raja SG, Pollock JC. Current outcomes of Ross operation for pediatric and adolescent patients J Heart Valve Dis 2007;16:27-36.[Medline]
  30. Kampmann C, Wiethoff CM, Wenzel A, et al. Normal values of M mode echocardiographic measurements of more than 2000 healthy infants and children in central Europe Heart 2000;83:667-672.[Abstract/Free Full Text]




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ANN THORAC SURG ASIAN CARDIOVASC THORAC ANN EUR J CARDIOTHORAC SURG
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