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Transvenous cardiac pacing in children: problems and complications during follow-up / Cocuklarda transvenoz pacemaker tedavisi deneyimlerimiz: Izlemde problem ve komplikasyonlar.

ABSTRACT

Objective: Transvenous permanent cardiac pacing (TPCP) has become a frequently used therapeutic modality in children. The purpose of this study was to evaluate the outcome of pediatric TPCP regarding problems and complications.

Methods: Records of 155 patients (mean age 9.2 [+ or -] 4.7 years) who underwent implantation of TPCP between 1993 and 2003 were reviewed retrospectively. Indications for pacing included atrioventricular block in 76% and sinus node dysfunction in 22% patients. In 92 patients, bradyarrhythmia was secondary to cardiac surgery. Percutaneous subclavian puncture was used for lead implantation in 96% of patients. Pacemakers were placed to the right side of the chest in 84% and in the subpectoral area in 68%. Pacing modes were VVIR in 72%, VDD in 13%, AAIR in 8%, and DOD in 7% of patients atthe initial implantation time. Of all electrodes, 95% had steroid elution and 53% had an active fixation mechanism. Mean follow-up period was 37 [+ or -] 28 (1-120) months.

Results: Forty-five (29%) patients had 21 minor and 45 major complications. Forty-four of 76 revisions were due to lead problems and battery extraction. Most of the lead problems were dislodgment and stretching (n=14). Kaplan Meier analysis of lead survival did not show any difference between lead types. During the follow-up, there were three sudden unexpected deaths.

Conclusions: In children, TPCP can be used safely and effectively. Although, complications are possible and sometimes lead or generator revision may be necessary, long-term outcome is favorable. (Anadolu Kardiyol Derg 2007- 7.- 292-7)

Keywords: Endocardial pacing, childhood, complications

OZET

Amac: Kalici transvenoz pacemaker tedavisi cocuklarda da siklikla kullanilan bir tedavi yontemi olmaktadir. Bu calismanin amaci pil tedavisinin cocuklarda uzun donem problem ve komplikasyonlanni belirlemektir.

Yontemler: Bin dokuz yuz doksan uc-iki bin uc yillarmda pacemaker yerlestirilen 155 hastanin (ortalama yas 9.2 [+ or -] 4.7 yil) kayrtlan geriye yonelik olarak incelendi. Pil gereksinimi %76 atriyoventrikuler blok, %22 hastada sinus nod disfonksiyonuydu. Bradiaritmi 92 hastada kalp cerrahisine ikincil gelismisti. Elektrotlar %96 oraninda perkutan subklaviyan girisim ile yerlestirildi. Pacemaker %84 gogsun sag tarafma, %68 subpektoral bolgeye yerlestirildi. Pil modlan %72 VVI, %13 VDD, %8 AAI ve %7 DDD seklindeydi. Elektrotlar %95 steroid iceren, %53 aktif sabitleme mekanizmaliydi. Izlem zamani ort 37 [+ or -] 28 (1-120) ay olarak belirlendi.

Bulgular: Hastalarnin 45'inde (%29), 21 minor ve 45 major komplikasyon oldu. Revizyonlarin %58'i elektrot problemi ve pil cikarilmasi nedeni ileydi. Elektrot problemlerin cogunlugu yer degistirme ve gerilme (14 kez) seklinde oldu. Kaplan Meier yasam analizi ile elektrot tipleri arasinda istatistiksel anlamli bir fark gosterilemedi. Izlem sirasinda beklenmeyen uc ani olum oldu.

Sonuc: Komplikasyonlar olabilmesine ve bazen elektrot ve pil revizyonu gerekebilmesine ragmen cocuklarda pil implantasyonu guvenli ve etkili bir sekilde yapilabilir. (Anadolu Kardiyol Derg 2007; 7:292-7)

Anahtar kelimeler: Endokardiyal pil yerlestirilmesi, cocukluk cagi, komplikasyonlar

Introduction

Permanent transvenous cardiac pacing in children is being used increasingly. Long-term pacing therapy has become more reliable with developments in lead and generator technology and implantation techniques (1, 2). There are several reports describing the utility and usefulness of epicardial pacemaker system. Although epicardial pacing is useful to spare the venous system, there are various pitfalls of epicardial pacing (3, 4). After the infancy period, it is advised to implant endocardial pacemakers (5). Endocardial pacing systems have many advantages, including lower capture thresholds and fewer lead problems. There are few reports of medium-term results of endocardial pacing in children (6, 8).

In this study, we retrospectively evaluated the long-term results of transvenous pacemaker treatment in children underwent pacemaker implantation, and data regarding the indications, methods, complications and revisions in children in our center.

Methods

Patient characteristics: From January 1993 to December 2003, 155 patients received permanent transvenous pacing systems in the department of Pediatric Cardiology of Hacettepe Medical School. There were 62 males (40%), 93 females (60%) with a mean age 9.2 [+ or -] 4.7 (9 months to 22 years) years, and body weight 29 [+ or -] 15 (6.4-80) kg. Their records were reviewed retrospectively. The patients were monitored with 1587 outpatient visits (3.4 per patient/year) during follow-up.

Evaluation included routine clinical examination, electrocardiogram, chest X-ray, echocardiogram, and a full analysis of the pacing system measurements. The voltage stimulation threshold at 0.5-ms pulse width, pacing impedance, and R or P wave amplitude were assessed at time of implantation, 2nd day, 4th week, 3rd month, 6th month, and every six months thereafter. The 24-hour ambulatory electrocardiographic monitoring and, if the patient was suitable, treadmill exercise testing was performed every year.

Pacing indications: Indications for pacemaker implantation included advanced second- or third degree surgical/acquired (n=84, 54%), congenital (n=38, 25%) atrioventricular block (AVB), sinus node dysfunction (SND) (n=29, 19%) and other reasons such as long QT syndrome and hypertrophic cardiomyopathy (n=4, 3%) (Table 1). Of all, 67 (43%) patients had had implanted epicardial lead system previously. Ventricular septal defect closure (n=21), total correction for tetralogy of Fallot (n=18), and subaortic resection (n=13) were the most frequent cardiac operations leading to postoperative AVB. Mean time to implantation time for postoperative AVB was 19 days following surgery. Of the 77 patients with surgical AVB, five patients had also sinus node dysfunction in addition to late onset AVB. Eight (21%) of the patients with congenital AVB had structural congenital heart disease. The most common lesion was congenitally corrected transposition of the great arteries. Among the patients with acquired AVB (n=7), cardiomyopathy and/or myocarditis were present in four.

When the patients with surgical AVB (n=77) were excluded, 40 (51%) of the remaining 78 patients had symptoms related to bradycardia, such as seizures, syncope, presyncope, dizzy spells (n=19, 24%), and exercise intolerance (n=21, 27%). Although the remaining 38 patients with severe bradycardia were asymptomatic, 15 (19%) of them had a pause >3 seconds while awake or >5 seconds while sleeping, 10 (13%) of them had complex ventricular arrhythmias, and five (6%) of them had left ventricular dysfunction associated with severe bradycardia.

Twenty-four of 34 patients with SND had a congenital heart defect or previous cardiac surgery. All of them were symptomatic and eight of 34 (24%) were defined as having brady-tachy syndrome. Five of 34 SND patients also had concomitant atrioventricular conduction disturbance, as mentioned above. Pacemaker implantation was performed in this subgroup at mean of 410 days following surgery.

Twenty-five of 155 patients (16%) were pacemaker dependent, with an intrinsic heart rate less than 30 bpm. Twenty-one of them (84%) had postoperative brady-dysrhythmia.

Implantation procedure: The same cardiologist performed the implantation procedure in the catheterization laboratory under general anesthesia. Endocardial leads were implanted by the percutaneous subclavian technique in 96% of cases. The pacemaker pocket was placed beneath the pectoral muscle in 92 patients (59%) and subcutaneous in 49 patients (32%) through the subclavicular incision, and under the pectoral muscle in 14 patients (9%) through the axillary incision at the initial implantation. Pacemakers were placed to the right side in 84% and left side in 16% of patients, respectively. Patients were discharged from the hospital between the second to fifth days after implantation.

Battery type: Pacing modes were VVIR in 112 (72%), VDD in 20 (13%), AAIR in 12 (8%), and dual chamber devices (DDD) in 11 (7%) patients at the initial implantation. Mean age was 7.8 [+ or -] 4.5 (0.75-21) years in VVIR, 12.2 [+ or -] 5.8 (1.1-22) years in AAIR, 13.1 [+ or -] 2.6 (7-16) years in DDD, and 10.2 [+ or -] 3.9 (1.3-17) years in VDD pacing group. Initial pacemaker mode was based on cardiac status, age, and weight of the patient.

Electrode characteristics: In 155 patients, 166 leads were used at the initial implantation. Additionally, 25 leads were required due to revisions or upgrading from single to dual chamber pacing during the follow-up. Active fixation leads with steroid eluting (n=102, 53%), passive fixation leads with steroid eluting (n=80, 42%) were used in the majority of the patients. There were no differences regarding age (9.3 [+ or -] 4.8 vs 8.8 [+ or -] 4.9 years, p=0.46) and weight (29.4 [+ or -] 16 vs 27.6 [+ or -] 14.6 kg, p=0.45) between patients with these two types of electrodes. Seven patients with congenitally corrected transposition of the great arteries had implanted screw-in leads placed into the anatomic left ventricle.

Statistical analysis: Exploratory data analysis was performed using descriptive measures. All ages reported are mean ages at implantation. Data are expressed as mean [+ or -] SD. One-way analysis of variance (ANOVA) with Bonferroni corrected post hoc t test was used to compare the threshold, impedance and R/P wave values within active and passive lead groups. The comparison of lead characteristics between active and passive lead groups were done using Student's unpaired t test. A p value of <0.05 was considered significant. Survival analysis was assessed by using Kaplan Meier analysis with significance based on the log-rank test. Survival time was calculated from the date of implantation to the date of lead related events or unknown death of the patient. The analyses were performed using the Statistical Package for the Social Sciences 11.0 (SPSS, Inc., Chicago, IL, USA) for Windows computer program.

Results

Electrical measurements (Table 2): The changes in electrical characteristics during the 3 follow-up measurements within groups were not significant (p>0.05). There were no significant differences regarding ventricular thresholds, ventricular lead impedance, intrinsic R wave amplitudes, atrial thresholds between ventricular active and passive electrode groups at the implantation, third month and the end of the follow-up period. There were significant differences between groups in atrial impedance (3rd month - p=0.03) and P wave amplitude (p=0.001 for 3rd month and p=0.04 for the end of follow-up) during follow-up period.

Complications: Forty-five patients (29%) developed 66 complications, 16 of them were detected in first 15 days after implantation and the others occurred thereafter. Twenty-one of them were minor and 45 (68%) were major. Major complications are noted in Figure 1. Beyond the implant time, the most frequent minor complications were muscle and phrenic nerve stimulation, and major complications were lead stretching and dislodgment (Fig. 1). No patient developed syncope or presyncope. Seven of the eight of dislodgements were seen in patients with passive fixation leads.

[FIGURE 1 OMITTED]

Lead survival: Follow-up was available for 133 patients. The mean follow-up period was 37 [+ or -] 28 (range 1 to 120) months. Lead related events were encountered 13 times; loss of pacing and sensing in five, fracture in four, unknown death in three, damage to screw mechanism in one patient. Lead survival was 33 [+ or -] 27 months in active fixation group and 41 [+ or -] 28 months in passive fixation group. Kaplan Meier survival analysis did not show any difference in their distributions with log rank test (p=0.78).

Lead or battery revisions: During follow-up, 76 patients required revision. Forty-three (57%) of them were related to the pacemaker, with the most common reason being battery end-of-life (n=32, 42%). Lead revision was required 33 times, with the most common reason being lead dislodgment and stretching (n=14, 19%) (Fig. 2).

[FIGURE 2 OMITTED]

Deaths: There were eight deaths. Five of them were related to the underlying cardiac diseases. First one was thromboembolic event at the gravity in one who had mitral valve replacement; second -dysfunctional prosthetic aortic valve with severe congestive heart failure and chronic atrial fibrillation; third had atrial fibrillation with rapid ventricular conduction; fourth--severe congestive heart failure with dilated cardiomyopathy, and last one died due to the postoperative infectious complications. There were three sudden unexpected deaths, including two patients who had open cardiac surgery. None of them was pacemaker-dependent. The cause of death was unknown, but battery malfunction and/or exit block could not be excluded as possible etiologies. Their follow-up periods were 43, 23 and 3 months and their pacing mode was VVIR.

Discussion

In the present study, we report our long-term experience with endocardial cardiac pacing in 155 children up to a 9-year follow-up. The indications for permanent pacing in children are well established (5, 8, 9). Pacing in the pediatric patient is more difficult because of the size of the patient (5, 7). Transvenous pacing in children has become widespread since the early 1980s. In our unit, we prefer epicardial system at the infancy period. The improved reliability and long life of cardiac pulse generators justify pacing in symptomatic patients and those with potentially life-threatening conditions. A pediatric patient can anticipate receiving 10 to 15 pacemaker implantations during his lifetime (8). In our study, the most common indication for pacing was bradyarrhythmias following cardiac surgery.

Placing one lead in children is technically easier than two leads and theoretically has a lower risk for venous obstruction (10). The incidence of venous obstruction following implantation of transvenous pacing leads in children was found to have a large spectrum from 2-5% to 18% (10, 11). However, most of pediatric patients with stenosis or occlusions of the venous system have venous collateral formation. No clinical signs of occlusion were observed in our patients except one. This patient was managed by oral antiplatelet treatment to prevent arm swelling.

Rate adaptive pacing mayfurther improve functional status by increasing exercise capacity and this pacing mode produced equivalent exercise improvement when compared to the DOD mode (8, 12). Use of relatively reliable sensors mimicking daily activity has improved the rate adaptation mechanism of these pacemakers. Although, we have used rate responsive systems in most of our patients, the main difficulty for these pacing systems was the adjustment of appropriate rate response factor. Pacemaker syndrome may develop in some children with single chamber ventricular pacing. Pacing system upgrading may be necessary in these children to solve this problem during follow-up (13).

Active fixation leads are much easier to stabilize and more easily provide acceptable pacing and sensing indices when underlying anatomy is altered. Scar tissue formation due to cardiac surgery and anatomic variations due to congenital heart disease may limit available sites for implantation of passive fixation leads. Children are more active then adults and lead displacement may be more frequent (14-17). Although dislodgement may occur with active and passive fixation leads, current data show that active fixation reduces the incidence of lead dislodgement. Passive leads with auto capture function had been used more than active ones at the beginning of this study. We have shown that two leads did not differ significantly in ventricular sensing or pacing properties, however, the study was retrospective, not controlled and the recipients and site of implantation were not homogeneous in the groups. Pacing and sensing thresholds generally were good with minimally observed acute to chronic threshold changes. In addition, septal pacing can improve myocardial dysfunction secondary to right ventricular apical pacing, which is possible with active fixation electrodes (18).

Pacing leads are the most important part of the transvenous pacing system, since any problem related with this component may necessitate a serious intervention. The most common causes for lead revision include high threshold, lead migration, lead fracture, insulating defects, subcutaneous tissue infection, recovery of iatrogenic AV13, lead migration, lead trapped in a valve, too many leads, pain, and venous thrombosis (15-17, 19). In this study, pacemaker and lead-related complications were relatively frequent; 29% of patients experienced a complication related to their pacemaker system. The most common complications were lead dislodgement and infection of pacing system. The use of an active fixation mechanism may prevent lead dislodgement (15-17). We did not see any case of lead migration in the last five years owing to use of these electrodes routinely. Lead and pacing system infection may necessitate intervention, since they cannot be managed by medical treatment with antibiotics or local drainage alone (19). Lead fracture at the thoracic entry was another important complication, and a new electrode insertion had been required (20). Lead revisions and removal could be performed successfully in most cases without major complications. However, the large size of laser sheaths may preclude the use of this system in small children (20).

Patient growth may produce lead stretching and tricuspid valve interference. In our study group, we performed revisions to treat this problem without serious complication. Nevertheless, in most cases, the complications were not dangerous and could be managed appropriately.

Our results indicate that endocardial pacing is feasible in children. Although lead-related complications were relatively frequent, they could be managed without significant morbidity and mortality. Lead extraction tools designed for children may be useful for the treatment of lead problems. Smaller pulse generators and steroid-eluting active fixation leads are few of the technological advances that have made pacing in children easier, safer, and more durable. Continued experience may result in further improvements in endocardial pacing in children.

References

(1.) Hayes DL, Holmes DR, Maloney JD, Neubauer SA, Ritter DG, Dannielson GK. Permanent endocardial pacing in pediatric patients. J Thorac Cardiovasc Surg 1983; 85: 618-24.

(2.) Till JA, Jones S, Rowland E, Shinebourne EA, Ward DE. Endocardial pacing in infants and children 15 kg or less in weight: medium-term follow-up. Pacing Clin Electrophysiol 1990;13: 1385-92.

(3.) Cutler NG, Karpawich PP, Cavitt D, Hakimi M, Walters HL. Steroid-eluting epicardial pacing electrodes: six-year experience of pacing thresholds in a growing pediatric population. Pacing Clin Electrophysiol 1997; 20: 2943-8.

(4.) Sachweh JS, Vazquez-Jimenez JF, Schondube FA, Daebritz SH, Dorge H, Muhler EG, et al. Twenty years experience with pediatric pacing: epicardial and transvenous stimulation. Eur J Cardiothorac Surg 2000;17: 455-61.

(5.) Gillette PC, Zeigler VL, Winslow AT, Kratz JM. Cardiac pacing in neonates, infants, and preschool children. Pacing Clin Electrophysiol 1992; 15: 2046-9.

(6.) Lau YR, Gillette PC, Buckles DS, Zeigler VL. Actuarial survival of transvenous pacing leads in a pediatric population. Pacing Clin Electrophysiol 1993; 16: 1363-7.

(7.) Molina JE, Dunnigan AC, Crosson JE. Implantation of transvenous pacemakers in infants and small children. Ann Thorac Surg 1995; 59: 689-4.

(8.) Maginot KR, Mathewson JW, Bichell DP, Perry JC. Applications of pacing strategies in neonates and infants. Prog Pediatr Cardiol 2000;11: 65-75.

(9.) Friedman RA, Fenrich AL, Kertesz NJ. Congenital complete atrioventricular block. Pacing Clin Electrophysiol 2001; 24: 1681-8.

(10.) Celiker A, Tokel K, Balkanci F, Cekirge S, Oto A, Ozme S. Venous obstruction due to insertion of permanent transvenous pacemaker electrodes in children. Cardiol Young 1997; 7: 375-7.

(11.) Figa FH, McCrindle BW, Bigras JL, Hamilton RM, Gow RM. Risk factors for venous obstruction in children with transvenous pacing leads. Pacing Clin Electrophysiol 1997; 20: 1902-9.

(12.) Celiker A, Alehan D, Tokel NK, Lenk MK, Ozme S. Initial experience with dual-sensor rate-responsive pacemakers in children. Eur Heart J 1996; 17: 1251-5.

(13.) Horenstein MS, Karpawich PP. Pacemaker syndrome in the young: Do children need dual chamber as the initial pacing mode? Pacing Clin Electrophysiol 2004; 27: 600-5.

(14.) Friedman RA, Moak JP, Garson A. Active fixation of endocardial pacing leads: The preferred method of pediatric pacing. Pacing Clin Electrophysiol 1991;14: 1213-6.

(15.) Celiker A, Alehan D, Oto A, Ozme S. Long-term clinical experience with a steroid-eluting active fixation ventricular electrode in children. Am J Cardiol 1997; 80: 355-8.

(16.) Campbell RM, Raviele AA, Hulse EJ, Auld DO, McRae GJ, Tam VK, et al. Experience with a low profile bipolar, active fixation pacing lead in pediatric patients. Pacing Clin Electrophysiol 1999; 22:1152-7.

(17.) Ceviz N, Celiker A, Kucukosmanoglu O, Alehan D, Kilic A, Uner A, et al. Comparison of mid-term clinical experience with steroid-eluting active and passive fixation ventricular electrodes in children. Pacing Clin Electrophysiol 2000; 23: 1245-9.

(18.) Karpawich PP. Chronic right ventricular pacing and cardiac performance: The pediatric perspective. Pacing Clin Electrophysiol 2004; 27: 844-9.

(19.) Klug D, Vaksmann G, Jarwe M, Wallet F, Francart C, Kacet S, et al. Pacemaker lead infection young patients. Pacing Clin Electrophysiol 2003; 26: 1489-93.

(20.) Friedman RA, Van Zandt H, Collins E, LeGras M, Perry J. Lead extraction in young patients with and without congenital heart disease using the subclavian approach. Pacing Clin Electrophysiol 1996;19: 778-83.

Alpay Celiker, Osman Baspmar, Tevfik Karagoz

From the Department of Pediatric Cardiology, Faculty of Medicine, Hacettepe University, Ankara, Turkey
Table 1. Pacing indications and symptoms related required
pacemaker therapy

 Pacing indications n (%)

Surgical or acquired AV block 84 (54)
 VSD closure operation 21
 TOF operation 18
 Subaortic resection operation 13
 Cardiomyopathy and/or myocarditis 7
 Other cardiac operations 25

Congenital reasons 67 (43)
 Atrioventricular block 38
 Sinus node dysfunction 29

Other Long QT syndrome and hypertrophic 4 (3)
 cardiomyopathy 4 (3)

 Pacing symptoms n (%)

Postoperative status 77 (50)
Bradycardia related seizures, syncope, presyncope 19 (12)
Bradycardia related exercise intolerance 21 (13.5)
Asymptomatic bradycardia 38 (24.5)

AV- atrioventricular, TOF- tetralogy of Fallot, VSD - ventricular
septal defect

Table 2. Pacing and sensing measurements in groups with different
types of leads

Parameters Time Passive fixation group

Ventricular capture Implantation 0.6 [+ or -] 0.7
threshold, V 3rd month 1.0 [+ or -] 0.6
 End of follow-up 2.4 [+ or -] 10.2
 * F 0.468
 * p 0.497

Ventricular lead Implantation 607 [+ or -] 132
impedance, Ohm 3rd month 619 [+ or -] 164
 End of follow-up 634 [+ or -] 207
 * F 1.135
 * p 0.290

R wave, mV Implantation 8.5 [+ or -] 3.5
 3rd month 9.1 [+ or -] 4.5
 End of follow-up 9.8 [+ or -] 7.1
 * F 1.008
 * p 0.329

Atrial capture Implantation 1.0 [+ or -] 0.8
threshold, V 3rd month 1.2 [+ or -] 0.6
 End of follow-up 0.8 [+ or -] 0.3
 * F 0.315
 * p 0.631

Atrial lead Implantation 590 [+ or -] 139
impedance, Ohm 3rd month 643 [+ or -] 50
 End of follow-up 775 [+ or -] 106
 * F 0.719
 * p 0.486

P wave, mV Implantation 3.9 [+ or -] 2.0
 3rd month 1.2 [+ or -] 0.7
 End of follow-up 1.3 [+ or -] 1.3
 * F 0.422
 * p 0.544

Parameters Active fixation group p **

Ventricular capture 0.6 [+ or -] 0.2 0.825
threshold, V 1.06 [+ or -] 0.6 0.927
 1.2 [+ or -] 0.7 0.379
 1.523
 0.223

Ventricular lead 589 [+ or -] 110 0.395
impedance, Ohm 631 [+ or -] 149 0.675
 606 [+ or -] 166 0.424
 2.539
 0.117

R wave, mV 10.4 [+ or -] 5.7 0.061
 11.2 [+ or -] 6.8 0.186
 10.5 [+ or -] 7.0 0.664
 0.367
 0.558

Atrial capture 0.9 [+ or -] 0.4 0.780
threshold, V 1.2 [+ or -] 0.4 0.966
 1.0 [+ or -] 0.5 0.341
 0.703
 0.415

Atrial lead 533 [+ or -] 138 0.440
impedance, Ohm 540 [+ or -] 133 0.039
 553 [+ or -] 142 0.158
 0.015
 0.904

P wave, mV 2.9 [+ or -] 1.1 0.090
 3.1 [+ or -] 1.5 0.001
 3.0 [+ or -] 1.7 0.014
 0.916
 0.361

* F test and p values for one way ANOVA analysis comparison of lead
characteristics through 3 measurements within groups, ** p - values
for Student's unpaired t test for comparison between groups data

mV- millivolts, V- volts
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Title Annotation:Original Investigation / Orijinal Arastirma
Author:Celiker, Alpay; Baspmar, Osman; Karagoz, Tevfik
Publication:The Anatolian Journal of Cardiology (Anadolu Kardiyoloji Dergisi)
Article Type:Clinical report
Geographic Code:7TURK
Date:Sep 1, 2007
Words:3822
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