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H Bertram

Publications and source records attributed to H Bertram.

At least 19 recordsLinked to original sources
PubMed2004

Incidence and time course of intimal plaque formation in the right coronary artery after radiofrequency current application detected by intracoronary ultrasound.

BACKGROUND: Despite the current clinical use of radiofrequency (RF) catheter ablation in infants and children, the late effects of RF current application at immature myocardium remain unclear. The purpose of this study was to investigate incidence and time course of coronary lesions after RF current application at developing myocardium in an animal model. RESULTS: In 10 pigs, 6 weeks of age (13+/-2 kg), RF current (500 kHz) was delivered by temperature guidance (75 degrees C) using a steerable electrode catheter (4 mm tip electrode) over 30-second periods. RF lesions were created at the lateral right atrial wall at the tricuspid valve annulus and the lateral left atrial and ventricular wall at the mitral valve annulus. Subsequent coronary angiography and intracoronary ultrasound (ICUS) of the right coronary artery (RCA) and the left circumflex artery (CX) were performed 3, 6, 9 and 12 months after RF current application. Quantitative coronary angiography did not exhibit any significant stenosis of the vessels during the study period. Intimal lesions of the RCA were documented for the first time at the 6-month study in 3 animals by ICUS (mean plaque area 2.2+/-0.2 mm(2), mean area stenosis 30.4+/-4.0%). There was no significant change in lesion length, area stenosis and plaque area at the 9- and 12-month studies. All 3 coronary artery lesions were confirmed in close proximity to myocardial RF lesions by histological examination 12 months after RF delivery. No intimal plaque formation of the CX was observed. CONCLUSIONS: Affection of the RCA as a late sequel after RF current application at the lateral right atrial wall occurred in 3 out of 8 long-term surviving pigs. Three to six months seem to be the time frame for the development of intimal lesions after RF delivery. In this experimental setting, angiography failed to detect these intimal changes. The potential risk of coronary affection may be important for catheter ablation procedures at the right atrial myocardium in infants and small children.

Animals↗
PubMed2004

Preoperative localization of parathyroid glands. Use of MRI, scintigraphy, and image fusion.

AIM: Minimally invasive resection of hyperfunctional parathyroid glands is an alternative to open surgery. However, it requires a precise preoperative localization. This study evaluated the diagnostic use of magnetic resonance (MR) imaging, parathyroid scintigraphy, and consecutive image fusion. PATIENTS, METHODS: 17 patients (9 women, 8 men; age: 29-72 years; mean: 51.2 years) with primary hyperparathyroidism were included. Examination by MRI used unenhanced T1- and T2-weighted sequences as well as contrast-enhanced T1-weighted sequences. (99m)Tc-MIBI scintigraphy consisted of planar and SPECT (single photon emission tomography) imaging techniques. In order to improve the anatomical localization of a scintigraphic focus, SPECT-data were fused with the corresponding MR-data using a modified version of the Express 5.0 software (Advanced Visual Systems, Waltham, MA). Results of image fusion were then compared to histopathology. RESULTS: In 14/17 patients, a single parathyroid adenoma was found. There were 3 cases with hyperplastic glands. MRI detected 10 (71%), scintigraphy 12 (86%) adenomas. Both modalities detected 1/3 patients with hyperplasia. Image fusion improved the anatomical assignment of the 13 scintigraphic foci in five patients and was helpful in the interpretation of inconclusive MR-findings in two patients. CONCLUSIONS: Both MRI and (99m)Tc-MIBI scintigraphy sensitively detect parathyroid adenomas but are less reliable in case of hyperplastic glands. In case of a scintigraphic focus, image fusion considerably improves its topographic assignment. Furthermore, it facilitates the evaluation of inconclusive MRI findings.

Adult↗
PubMed2003

[Arrhythmogenic right ventricular dysplasia/cardiomyopathy - diagnosis in childhood].

Arrhythmogenic right ventricular dysplasia/cardiomyopathy (ARVD/C) is a rare, but important cause for sudden death in adolescents and young adults. Part of the patients affected show the pattern of autosomal-dominant inheritance. Two pediatric patients with ARVD/C are presented who may reflect the spectrum of clinical presentation of ARVD/C in childhood resulting in difficulties or even delay to establish the correct diagnosis. One patient with a sporadic form of ARVD/C presented with a syncope and spontaneous as well as inducible ventricular tachycardia. On the ECG, an epsilon wave could be identified. An automatic cardioverter defibrillator was implanted. The second patient had a familiar form of ARVD/C with no symptoms. There was a history of frequent sudden deaths in this family. Biopsies of the right ventricular myocardium showed fibrosis with deposition of fatty tissue. There was clear evidence of ARVD/C in the necropsy of the patient's aunt. Therapy with propanolol was started in this patient.

Adolescent↗
PubMed2003

Interventional treatment of infantile hepatic hemangioendothelioma.

BACKGROUND/PURPOSE: Hemangioendothelioma is the most frequent liver tumor in infancy. Untreated symptomatic patients with heart failure have a high mortality rate. Symptomatic forms may request nonoperative treatment, because surgery is burdened with high risks in patients with heart failure. The authors report their experience with interventional coil occlusion of infantile hepatic hemangioendothelioma (IHE). METHODS: Four patients (age range, 2 to 146 days; mean, 53 days) suffering from IHE associated with heart failure were treated by endovascular coil occlusion of arterial feeders. Catheter intervention was performed via an arterial (n = 2) or venous (n = 2) approach. RESULTS: Signs of heart failure resolved within 2 to 8 days after occlusion in 3 patients. Tumor regression could be observed sonographically within 4 weeks postinterventionally. In 3 children, tumor size was reduced from a mean of 544 mL (65 to 1,350) to a mean of 4 mL (2 to 6); Mean systolic peak velocity in the hepatic artery was decreased from 170 cm/s (140 to 200) before occlusion to 45 cm/s (36 to 70) during follow-up. In the fourth patient, endovascular intervention could not control a rapidly progressing hemangioendotheliomatosis, and finally a liver transplantation had to be performed. CONCLUSIONS: Interventional occlusion of feeding arteries in symptomatic IHE is a safe and effective alternative to early open surgery. The efficacy of endovascular intervention in multifocal tumors seems questionable.

Blood Flow Velocity↗
PubMed2003

Use of statistical parametric mapping of (18) F-FDG-PET in frontal lobe epilepsy.

AIM: Evaluation of the use of statistical parametrical mapping (SPM) of FDG-PET for seizure lateralization in frontal lobe epilepsy. PATIENTS: 38 patients with suspected frontal lobe epilepsy supported by clinical findings and video-EEG monitoring. METHOD: Statistical parametrical maps were generated by subtraction of individual scans from a control group, formed by 16 patients with negative neurological/psychiatric history and no abnormalities in the MR scan. The scans were also analyzed visually as well as semiquantitatively by manually drawn ROIs. RESULTS: SPM showed a better accordance to the results of surface EEG monitoring compared with visual scan analysis and ROI quantification. In comparison with intracranial EEG recordings, the best performance was achieved by combining the ROI based quantification with SPM analysis. CONCLUSION: These findings suggest that SPM analysis of FDG-PET data could be a useful as complementary tool in the evaluation of seizure focus lateralization in patients with supposed frontal lobe epilepsy.

Adolescent↗
PubMed2002

[Transcatheter closure of atrial septal defects with the CardioSEAL occluder].

Data on mid- and long-term follow-up for the recent devices for closure of secundum-type atrial septal defects are limited. The purpose of our retrospective study was to report the effectiveness of transcatheter closure in patients with various morphological types of atrial septal defect other than centrally located defects within the oval fossa using the CardioSEAL and CardioSEAL-Starflex occluder. A total of 91 patients (age 1.5-71 years, median 6 years) underwent transcatheter closure. On the transesophageal echocardiogram, defect size varied from 6 to 18 mm with an estimated stretched diameter of 11 to 24 mm, median 15 mm; the ratio of the stretched diameter to septal length ranged from 0.28 to 0.68. Mean follow-up was 28.7 +/- 11,9 months (range 3-46 months). Isolated secundum-type defects were present in 59 patients (65%), multiple septal defects including patients with perforated atrial septal aneurysms and defects with deficient atrial rim in 32 patients (35%). Occlusion rate using device diameters from 23 to 40 mm increased from 66% (60/91 patients) immediately after implantation to 86% (48/56 patients) 24 months after implantation. Patients with isolated secundum-type defects presented with a significantly higher primary closure rate (45/59 patients, 76%) compared to patients with various defect morphology. Closure rate did not depend on the type of implanted device modification. No thrombus formation, sustained atrial arrhythmia or infective endocarditis occurred. Serial transthoracic echocardiographic findings revealed protrusion of one left-sided arm onto the right atrial aspect in 5 patients; malposition of one right-sided superior arm of the device was observed in 7 patients. Fluoroscopy showed single fatigue fracture in 7 patients (7.7%) within the first 6 months after implantation. These results demonstrate that transcatheter closure with the double umbrella device was effective and safe on medium-term follow-up and could be extended to atrial septal defects of various morphology.

Adolescent↗
PubMed2002

Stimulation of protein kinase C pathway mediates endocytosis of human nongastric H+-K+-ATPase, ATP1AL1.

The human nongastric H+-K+-ATPase, ATP1AL1, shown to reabsorb K+ in exchange for H+ or Na+, is localized in the luminal plasma membrane of renal epithelial cells. It is presumed that renal H+-K+-ATPases can be regulated by endocytosis. However, little is known about the molecular mechanisms that control plasma membrane expression of renal H+-K+-ATPases. In our study, activation of protein kinase C (PKC) using phorbol esters (phorbol 12-myristate 13-acetate) leads to clathrin-dependent internalization and intracellular accumulation of the ion pump in stably transfected Madin-Darby canine kidney cells. Functional inactivation of the H+-K+-ATPase by PKC activation is shown by intracellular pH measurements. Proton extrusion capacity of ATP1AL1-transfected cells is drastically reduced after phorbol 12-myristate 13-acetate incubation and can be prevented with the PKC blocker bisindolylmaleimide. Ion pump internalization and inactivation are specifically mediated by the PKC pathway, whereas activation of the protein kinase A pathway has no influence. Our results show that the nongastric H+-K+-ATPase is a specific target for the PKC pathway. Therefore, PKC-mediated phosphorylation is a potential regulatory mechanism for apical nongastric H+-K+-ATPase plasma membrane expression.

Animals↗
PubMed2001

Atrial reentrant tachycardia after surgery for congenital heart disease: endocardial mapping and radiofrequency catheter ablation using a novel, noncontact mapping system.

BACKGROUND: The purpose of the present study was to determine the role of a novel, noncontact mapping system for assessing a variety of atrial reentrant tachycardias (ART) in patients after the surgical correction of congenital heart disease. METHODS AND RESULTS: In 14 patients, an electrophysiological study using the Ensite 3000 system was performed to assess ARTs resistant to medical treatment. Sixteen different forms of ART were inducible in the 14 patients studied. The reentrant circuit of all ARTs could be characterized and localized with respect to anatomic landmarks such as atriotomy scars, intraatrial patches/baffles, and cardiac structures. In 15 of the 16 ARTs (in 13 of the 14 patients), a target area of the reentrant circuit for radiofrequency current application (ie, an area of conduction between 2 anatomical obstacles such as surgical barriers and cardiac structures of electrical isolation) could be localized within the systemic venous atrium. Nine patients exhibited macroreentry, and 4 showed microreentry. In 12 patients, ART could be terminated by creating linear radiofrequency current lesions (75 degrees C, 180 to 390 s). Completeness of linear lesions after radiofrequency current delivery was proven by analyzing color-coded isopotential maps of atrial activation while applying atrial pacing techniques. The mean duration of the procedures was 286 minutes (range, 130 to 435 minutes); fluoroscopy time ranged from 7 to 33.8 minutes (mean, 17.4 minutes). CONCLUSIONS: In patients with ART after the surgical correction of congenital heart disease, the use of the noncontact mapping system allows for characterization of the tachycardia and guidance for effective radiofrequency current delivery.

Adolescent↗
PubMed2001

Coronary artery stenosis after radiofrequency catheter ablation of accessory atrioventricular pathways in children with Ebstein's malformation.

BACKGROUND: Complications concerning the coronary arteries that are directly related to radiofrequency catheter ablation procedures have not been reported in children. Coronary artery lesions, however, have been demonstrated after the endocardial application of radiofrequency current in young animals. METHODS AND RESULTS: Two boys with Ebstein's anomaly of the tricuspid valve developed clinically asymptomatic coronary artery stenosis after radiofrequency catheter ablation of right-sided accessory atrioventricular pathways with standard catheter technology. CONCLUSIONS: The complication of coronary artery stenosis demonstrates a substantial risk after right atrial free wall radiofrequency current application in children. The risk of late coronary alterations should be considered when the use of catheter ablation procedures to young patients is proposed.

Atrioventricular Node↗
PubMed2001

Laboratory diagnosis of central nervous system infections.

The laboratory diagnosis of CNS infection is essential for optimal therapy. Acute infection requires rapid turn-around testing with high predictive values, that is, the ability of a test to accurately identify those patients who do or do not have disease caused by a specific etiology. The Gram's stain, fungal stains of direct smears, antigen testing for C. neoformans, and culture of bacteria, fungi, mycobacteria, and some viruses are important tests for the diagnosis of acute infection. The laboratory diagnosis of chronic infection necessitates discussion between the clinician and laboratory technician to allow triaging of testing. Antigen tests for bacteria, fungi, and viruses; antibody tests for multiple microorganisms; and PCR testing for bacteria, M. tuberculosis, and many viruses are all important in limited clinical situations. All testing for acute or chronic disease depends on sufficient specimen that is transported to the laboratory in a manner that will not compromise viability or chemical integrity. Sterile containers that maintain moisture content, exclude oxygen for anaerobic requests, and are stored at proper temperatures (22 degrees C room, 4 degrees C refrigeration, or -20 degrees C freezer depending on pathogen and test) are mandatory. Many laboratory issues addressing the diagnosis of CNS infection are changing or evolving. Most important is the recognition that bacterial antigen testing for the diagnosis of acute bacterial meningitis rarely impacts patient management and is not routinely needed, CSF shunt infections differ from usual meningeal infections and require rapid diagnosis, and TB meningitis remains a difficult disease to diagnosis but may be confirmed first by PCR testing of CSF. In addition, Whipple's disease of the CNS can be confirmed using PCR with CSF; CJD has a marker protein, referred to as 14-3-3 antigen, that can be detected in CSF, and the diagnosis of fungal CNS disease requires careful interpretation of direct smears, antigen and antibody testing, and culture. Most difficult to diagnose among the CNS infections are viral meningitis and encephalitis. The appearance of new etiologies, such as West Nile virus, and the common use of PCR for the herpes viruses and enteroviruses represent important advances. Evolving methods for the laboratory diagnosis of CNS infection represent significant improvements over previous testing; however, the array of tests available demands more attention for appropriate selection, is significantly more expensive, and requires new skills for performance and interpretation. The responsibility for proper use of laboratory testing lies both with the clinician and laboratory technician.

Antigens, Bacterial↗
PubMed2001

Abbreviated combined anatomical/electrophysiological approach for catheter ablation of atrioventricular nodal reentrant tachycardia in children.

Atrioventricular nodal reentrant tachycardia was proven during electrophysiologic study in 41 children, aged from 3.7 to 16 years, who were referred for catheter ablation of symptomatic supraventricular tachycardia. Using an abbreviated combined anatomical and electrogram-guided approach for selective ablation of the slow pathway, a steerable ablation catheter was placed at the inferior region of the vestibule of the tricuspid valve close to the orifice of the coronary sinus, with the intention of recording a multicomponent local atrial electrogramm during sinus rhythm. If application of radiofrequency current of 500 kHz at 70 degrees C at this site did not result in a slowly accelerated junctional rhythm, at a rate of less than 120 beats per minute, the catheter was stepwise advanced up to a position midway towards the apex of the triangle of Koch for additional applications of energy. Ablation was achieved in 35 of the patients. In 6 patients, the slow pathway was modulated such that the tachycardia could no longer be induced. The number of applications of energy ranged from 1 to 19, with a median of 6 applications. The mean period of fluoroscopy was reduced to 15.6 (4.3 to 39.8) minutes, while the overall duration of the catheterization procedures ranged from 88 to 280 (mean 173.2) minutes. In none of the patients did we observe permanent high grade atrioventricular block. During follow-up over a mean of 4.1 years, two patients had recurrence of tachycardia, corresponding to a 95% rate of success in the midterm. We conclude that selective radiofrequency ablation of the slow pathway using the abbreviated anatomical and electrophysiological approach is a safe and curative therapeutic approach in children with atrioventricular nodal reentrant tachycardia. Periods required for fluoroscopy can be significantly reduced, and mid-term results are excellent.

Adolescent↗
PubMed2001

Primary repair of tetralogy of fallot in infancy--the effect on growth of the pulmonary arteries and the risk for late reinterventions.

We sought to analyse the long-term follow-up after primary repair of tetralogy of Fallot in infancy in the first year of life, paying particular attention to growth of the pulmonary arteries and the need for reintervention. We performed a combined retro- and prospective echocardiographic study, including measurements of the pulmonary valve and right and left pulmonary arteries, indexed to the square root of body surface area, in 62 patients prior to primary repair, 18 to 24 months after this event, and at the most recent follow-up, with a mean of 80.4+/-24 months. Of these, 38 patients, with an age at operation of 5.0+/-3.4 months, had presented preoperatively with hypoxic spells or increasing cyanosis. The remaining 24 patients had been asymptomatic, with adequate flow of blood to the lungs. Their age at elective operation was 7.4+/-3.0 months. A transannular patch was needed in 37 patients (63%). There were 3 early postoperative deaths (4.8%). Cross-sectional echocardiography revealed a significantly smaller diameter for the pulmonary valve in patients who had been symptomatic preoperatively compared to the asymptomatic patients (1.09 versus 1.3 cm/BSA0.5; p = 0.019). The diameters of the right and left pulmonary arteries did not differ significantly between the groups. Examination of echocardiographic data obtained 18 to 24 months postoperatively in 43 patients revealed a significant increase in the diameter of the pulmonary arteries; 0.83+/-0.17 cm/BSA0.5 versus 1.1+/-0.26 cm/BSA0.5 for the diameter of the right pulmonary artery, 0.85+/-0.2 cm/BSA0.5 versus 1.0+/-0.25 cm/BSA0.5 for the left pulmonary artery. On comparison between individuals, 18.6% and 25.6% of the patients, respectively, did not show any change in the diameters of their right and left pulmonary arteries, whereas the increase in diameter reached or exceeded the measurements in normal controls in 55.8% and 46.5% of the patients, respectively. On recent follow-up, with a range from 56 to 147 months, no further increase in the indexed diameters of the pulmonaries could be documented in 21 of 33 patients. Of these, 9.1% and 18.2%, respectively, presented with small right and left pulmonary arteries compared with measurements obtained in normal controls. Moderate pulmonary incompetence was found on colour flow mapping in one-third. Of 56 longterm survivors, 8 (14%) had required reinterventions, which were surgical in 6 and achieved by transcatheter techniques in the other 2 patients. Thus, primary correction of tetralogy of Fallot in infancy, with restoration of normal pressures and flows, resulted in sustained increase in the diameters of the right and left pulmonary arteries. It allowed for early normal development of the proximal pulmonary arterial system in most patients regardless of their age and symptomatic status at operation. Patients with persistent subnormal diameter of the pulmonary arteries did not present with significantly elevated right ventricular pressure. Early one-stage repair of tetralogy of Fallot in infancy was associated with a low rate of reinterventions.

Age Factors↗
PubMed2001

Experimental preseeding of the STARFlex atrial septal occluder device with autologous cells.

Devices used in interventional cardiology are permanent implants. However, most of the devices fulfill only a temporary function. For example, atrial septal defect (ASD) occluders serve as mechanical shields until complete in- and overgrowth of the occluding device by endogenous tissue from the defect edges has occurred. Thereafter, the foreign body material of the devices is no longer needed and bears potential long-term adverse effects. The concept of "biodegradable" occluder devices that act as transient mechanical shields to close the defects and as scaffolds for overgrowth with autologous tissue is, therefore, tempting. Since rapid and complete ingrowth as well as coverage by firm tissue is a prerequisite for any such "biological" occluder devices, the feasibility and short-term in vivo response to STARFlex devices preceeded with autologous cells was studied in an experimental sheep model. The experiments demonstrated that autologous cell preceeding of cardiovascular implants is technically feasible. Cells survived the mechanical stress of device implantation. A precoating of conventional STARFlex occluders led to an increased cellular density after cell seeding of the device, an increased resistance of the precultured cytolayer against mechanical stress, and a significantly higher poststress viability of "implanted" cells. Experimental closure of ASD using autologous-cell preseeded STARFlex devices was uncomplicated. In the sheep model this led to rapid, complete, and firm ingrowth of the device into the adjacent atrial tissue. A thicker layer of young fibrous granulation tissue in organization was found on the preceeded devices compared with the unseeded control group after 4 weeks in vivo. Currently, an increased thrombogenicity limits in vivo application.

Cell Transplantation↗
PubMed2000

[In vitro manipulation of primary human osteo-progenitor cells for tissue technological bone production].

The aim of the present study was to evaluate the effect of three different techniques for isolation of human bone-marrow-derived mesenchymal stem cells (MSCs) on the in vitro differentiation of these cells. Furthermore, the use of BMP-2 was assessed and the effect of gene transfer of the BMP-2 gene into these cells was evaluated. Reverse transcription polymerase chain reaction showed that isolation of MSCs by outgrowth from cancellous chips resulted in expression of both osteogenic and chondrogenic markers, while cells cultivated from marrow aspirates exhibited only osteogenic markers. Intramuscular reimplantation of BMP-2-transfected cells in poly-(L/DL 70/30) lactic acid fleeces resulted in formation of mineralized tissue after 8 weeks in athymic rats, while control-transfected cells exhibited matrix synthesis without mineralized tissue after intramuscular reimplantation.

Animals↗
PubMed2000

[Atrioventricular nodal reentry tachycardia in children: curative treatment by high frequency catheter ablation].

BACKGROUND: Atrioventricular nodal reentrant tachycardia (AVNRT) is one of the most common forms of supraventricular tachycardia in the pediatric population. PATIENTS AND METHODS: 41 children with a mean age of 9.6 (3.7-16) years with recurrent atrioventricular nodal reentrant tachycardia (AVNRT) refractory to medical treatment (n = 38) and recurrent syncope (n = 3) underwent electrophysiologic (EP) study. In all patients dual AV-nodal physiology could be demonstrated during EP study and typical form of AVNRT (mean heart rate 220/min) could be induced by programmed atrial stimulation. A steerable 7 F ablation catheter was placed at the inferoparaseptal region of the tricuspid valve annulus close to the orifice of the coronary sinus with the intention to record a late fractionated local atrial electrogram during sinus rhythm. Starting at this point radiofrequency current (500 kHz) with a target temperature of 70 degrees C was delivered with the intention to ablate the slow pathway. If a slowly accelerated junctional rhythm (< 120/min) occurred during energy discharge, programmed atrial stimulation was repeated. Otherwise radiofrequency current was delivered step by step up to a septal position next to the tricuspid valve annulus. Slow pathway ablation was defined as lack of evidence of dual AV nodal pathways during repeated atrial stimulation. Slow pathway modulation was defined as maximal one atrial echoimpulse after ablation. RESULTS: The number of energy applications ranged from 1-19 (median 6). In 35/41 patients slow pathway ablation could be achieved; in six patients the slow pathway was modulated. In none of the patients permanent high grade AV block was observed. During follow-up (mean 4.1 years) two patients had a recurrent episode of AVNRT after slow pathway modulation. All other patients are still free of AVNRT without medical treatment. CONCLUSION: Selective radiofrequency current ablation/modulation of the slow pathway is a safe and curative treatment of AVNRT in young patients.

Adolescent↗
PubMed2000

[Supraventricular tachycardia in infants, children and adolescents: diagnosis, drug and interventional therapy].

Supraventricular tachycardias are the most frequent forms of symptomatic tachyarrhythmias in infants, children and adolescents. Clinical symptoms depend on age and underlying cardiac anatomy. Newborn babies and infants with paroxysmal atrioventricular reentrant tachycardias usually present with signs of congestive heart failure due to rapid heart rate. In older children and adolescents, palpitations are the leading symptom. Patients with chronic-permanent tachycardias (i.e., atrial ectopic tachycardia, permanent form of junctional reciprocating tachycardia) often develop a secondary form of dilated cardiomyopathy, the so-called "tachymyopathy". Adenosine has evolved as the drug of choice in any age group for the termination of atrioventricular reentrant tachycardia of any origin. In addition, it serves as a diagnostic tool in primary atrial tachycardias. Long-term management of atrioventricular reentrant tachycardia in infancy and childhood is age dependent. In newborn babies and infants, pharmacological therapy is advised due to the high spontaneous cessation rate of those tachycardias at the end of the first year of life. In contrast to this, the probability of spontaneous cessation of tachycardia in children > 1 year of age is very low. Therefore, radiofrequency catheter ablation of the anatomical substrate of the tachycardia is a rational alternative to long-lasting antiarrhythmic therapy. Results in children with a structurally normal heart are comparable to those achieved in adults. In patients with congenital heart disease and supraventricular tachycardias, catheter ablation during preoperative cardiac catheterization is recommended. Atrial reentrant tachycardias have been identified as one major risk factor for late postoperative morbidity and mortality in young patients. Pharmacological therapy is often not sufficient to control the tachycardia. In addition, underlying sinus node dysfunction may be aggravated in a considerable portion of the patients affected. Catheter ablation based on conventional endocardial mapping techniques by multipolar electrode catheters with the aim of identifying the critical region of the reentrant circuit is associated with an impaired success rate and a considerable recurrence rate. It may be assumed that, using the modern mapping techniques currently available (electroanatomical mapping and non-contact mapping), results of radiofrequency catheter ablation of atrial reentrant tachycardias after surgical correction of congenital heart disease will be significantly improved within the next few years.

Acute Disease↗
PubMed2000

Effects of intracardiac radiofrequency current application on coronary artery vessels in young pigs.

INTRODUCTION: Radiofrequency current is widely used in children to ablate accessory AV pathways. Previous data in a pig model demonstrated coronary artery obstruction adjacent to radiofrequency current lesions 48 hours and 6 months after energy delivery. In the present study, the long-term effects (>6 months) of radiofrequency current application on coronary artery vessels in young pigs are assessed. METHODS AND RESULTS: Radiofrequency current (500 kHz) was delivered over 30 seconds in ten piglets (mean body weight 12.8 kg) using a steerable 6-French catheter with a 4-mm thermistor tip electrode (target temperature 75 degrees C). Lesions were created under fluoroscopic and electrocardiographic guidance at the lateral right atrial (RA) wall above the tricuspid valve orifice, and at the lateral left atrial and left ventricular wall adjacent to the mitral valve orifice. Selective coronary angiography and intravascular ultrasound (IVUS) studies were performed 3, 6, 9, and 12 months after energy application. After 12 months, the lesions were studied pathohistologically. All lesions consisted of compact fibrous tissue. RA lesions extended to the adjacent right coronary artery and led to coronary artery involvement with increased fibrous tissue in the adventitia and media and intimal thickening in three animals. Coronary arterial narrowing was documented by IVUS during follow-up in all three cases 9 months after energy application. Angiography failed to demonstrate coronary pathology in any of the three animals. CONCLUSION: The risk of late coronary artery lesions must be considered when catheter ablation at the RA wall is planned in children with free-wall accessory AV pathways.

Animals↗