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Biomedical subjects

U Bauersfeld

Publications and source records attributed to U Bauersfeld.

At least 19 recordsLinked to original sources
PubMed2004

[Arrhythmias in pediatric patients].

Arrhythmias in children occur frequently as isolated phenomena, however, may also represent comorbidities of congenital heart disease. Therefore electrophysiologic assessments must include morphologic and hemodynamic evaluations. Besides the arrhythmias commonly seen in adults children present with arrhythmias unique to pediatric patients. Antiarrhythmic therapy depends on patient age, expected natural history of the arrhythmia and possible congenital heart disease. As in adult patients in addition to antiarrhythmic drug therapy radiofrequency catheter ablation is a preferred definitive treatment especially in patients with supraventricular tachycardias. Bradycardias can be successfully treated with pacing systems which can already be implanted in the newborn period. As antiarrhythmic treatment in pediatric patients may be very complex a referral to a pediatric cardiology center is recommended.

Adolescent↗
PubMed2004

Measurement of activated clotting time in children--comparison of the Celite i-STAT ACT with the Medtronic ACT II.

BACKGROUND: To evaluate a recently introduced blood-saving method for the measurement of activated clotting time (ACT), the Celite i-STAT ACT, by comparing the values obtained with those from the widely used Medtronic ACT II device. METHODS: In a prospective clinical study, we compared ACT values from the i-STAT device with the Medtronic ACT II device in 60 paediatric, interventional, cardiac catheterization procedures necessitating prophylactic heparinization. Blood samples were pair-analyzed using two i-STAT analyzers and one Medtronic ACT II device with double-tube-cartridges before and after heparinization. Data were compared using Bland-Altman bias analysis, Student's t-test and simple regression analysis. RESULTS: Bias and precision between the Medtronic ACT II and the i-STAT ACT values was -5.4 +/- 26.3. The i-STAT and Medtronic ACT II values were similar before heparinization (P = 0.22), but i-STAT ACT values became significantly longer than Medtronic ACT II values after heparinization (P = 0.021). The increase of ACT after heparinization was greater (median 86.3; range 40-187 s) in the i-STAT analyzer than in the Medtronic ACT II analyzer (median 73.0; range 19-235.5 s). Increase in ACT values was inversely affected by intraoperative haemoglobin concentration in the Medtronic ACT II analyzer (P = 0.001) but not in the i-STAT analyzer. CONCLUSION: Activated clotting times obtained from the Celite i-STAT ACT and the Medtronic ACT II demonstrated poor agreement. The technical principles are quite different and the two methods showed diverse susceptibility to intraoperative haemoglobin concentration. Users have to be aware of technique-specific ACT target ranges and their confounders, which need to be provided by the manufacturers.

Adolescent↗
PubMed2002

Long-term follow up of children with congenital complete atrioventricular block and the impact of pacemaker therapy.

AIMS: This study assessed survival, morbidity and impact of pacemaker (PM) therapy in children with Congenital Complete Atrioventricular Block (CCAVB). METHODS AND RESULTS: Data of 32 children, diagnosed as showing CCAVB at a median age of 0.4 years (range foetal-10 years), were retrospectively analysed. For comparison of clinical data patients were separated into two groups: CCAVB without structural heart disease (group 1; n = 23) and with structural heart disease (group 2; n = 9). Median follow-up time was 10.2 years. Pacemakers (PM) were implanted in 17 group 1 and all group 2 children. Frequency of PM therapy, age and symptoms before PM implantation did not differ significantly between the groups. Indications for PM implantation were bradycardia in 15, decreased exercise tolerance in 6, syncope in 3 and heart failure in 2 children. PM system related complications occurred in 11/26 (42%) children. Although 1 child died due to PM exit block no further CCAVB related symptoms were recorded in children with PM. CONCLUSION: PM therapy reduces mortality and morbidity in children with CCAVB when compared with natural history data. Although children with PM are free from CCAVB related symptoms limited morbidity remains due to PM system related complications.

Cardiac Pacing, Artificial↗
PubMed2001

Treatment of supraventricular tachycardias in the new millennium--drugs or radiofrequency catheter ablation?

UNLABELLED: Supraventricular tachycardias are a cause of significant morbidity in children. Newer anti-arrhythmic drugs and the invention of radiofrequency catheter ablation have revolutionised anti-arrhythmic therapy in children. CONCLUSION: With the availability of these very effective therapeutic options, an improved knowledge of these methods and their indications is required.

Anti-Arrhythmia Agents↗
PubMed2001

Transcatheter occlusion of the patent ductus arteriosus with a single device technique: comparison between the Cook detachable coil and the Rashkind umbrella device.

UNLABELLED: Transcatheter coil occlusion of the patent ductus arteriosus (PDA) has become the interventional treatment option of choice. Immediate occlusion of any residual shunting results in excellent closure rates, but frequently requires multiple coil deployment. AIMS: To assess the efficacy and limitations of single Cook detachable coil PDA closure compared to a preceding series of Rashkind umbrella procedures. METHODS AND RESULTS: Between 1990 and 1999, transcatheter occlusion of a small (<2 mm; n=45) or moderate-sized (2-4 mm; n=47) PDA was successfully attempted in 90/92 consecutive patients (mean age 6+/-4.8 years) with a coil (39/41) or Rashkind device (51/51). Immediate angiographic closure rates for both devices were low, although better for small (54-68%) than moderate ducts (7-22%, P<0.01). A 2-year echocardiographic closure rate of small ducts increased to 92% for the coil group versus 95% for the Rashkind group. By that time, moderate-sized ducts were only occluded in 64% with the coil and 54% with the Rashkind device. A visible residual shunt at post-implant angiography in moderate ducts was associated with a high incidence (59%) of long-term echocardiographic shunt patency and a need for repeat interventions for audible residual shunts (32%). CONCLUSIONS: Single coil transcatheter occlusion is the treatment of choice for the small duct as most residual shunts will resolve spontaneously. However, long-term shunt persistence after single coil deployment in moderate sized ducts is as frequent as with the Rashkind device. A primary multiple coil approach is advocated if the postcoil aortogram shows residual ductal shunting and if there is persistence of a ductal murmur on auscultation.

Cardiac Catheterization↗
PubMed2001

[Diagnosis and treatment of common pediatric supraventricular tachycardias].

The incidence of paediatric supraventricular tachycardias is approximately 0.1-0.4%. AV node and AV reentrant tachycardias represent the most common supraventricular tachycardias in children. Atrial ectopic tachycardias are the second most common group of pediatric arrhythmias with a predominance in younger children. All these arrhythmias may result in a significant morbidity and necessitate therapy. During the last decade the widespread use of newer antiarrhythmic agents and the invention of radiofrequency catheter ablation have revolutionized the treatment of supraventricular tachycardias in children. A thorough knowledge of these various treatments options is essential to achieve a safe and effective management of supraventricular tachycardias in children. This article focuses on diagnostic and therapeutic aspects of the most frequent supraventricular tachycardias.

Catheter Ablation↗
PubMed2001

Avoiding inappropriate ventricular tachycardia detection due to T-wave oversensing in an implantable cardioverter defibrillator: a novel application of the electrogram width criterion.

Appropriate sensing is an essential function of an implantable cardioverter defibrillator (ICD). T-wave oversensing by an ICD can be a serious problem in some patients, causing overestimation of the heart rate, inappropriate tachyarrhythmia detection and therapy delivery. Decreasing the sensitivity or programming longer refractory periods can sometimes overcome T-wave oversensing, but these measures may interfere with the ability of the ICD to correctly detect tachyarrhythmias. This report proposes a novel application of the electrogram (EGM) width criterion using a recently introduced detection enhancement algorithm intended to improve the specificity of ventricular tachycardia detection, to avoid T-wave oversensing. Based on the course of a case with persistent T-wave oversensing and review of previously published reports, oversensing problems in ICDs and management strategies are discussed.

Defibrillators, Implantable↗
PubMed2000

[Maternal cardiac arrhythmias in pregnancy].

During pregnancy an increased incidence of maternal cardiac arrhythmias is observed. These include a wide spectrum, from clinically irrelevant isolated premature beats to debilitating supraventricular and ventricular tachycardias. In principle, management of arrhythmias during pregnancy is similar to that in non-pregnant patients. However, special consideration should be given to foetal age and potential teratogenic and haemodynamic adverse drug effects on the foetus. Therapeutic strategy should be guided by interdisciplinary consulting (i.e. cardiology, obstetrics, neonatology). Diagnostic evaluation must rule out underlying cardiovascular, pulmonary, endocrine or metabolic diseases. Additionally, precipitating factors such as excessive caffeine and/or alcohol ingestion and cigarette smoking should be avoided. For benign arrhythmias a conservative approach is appropriate. Antiarrhythmic drug selection depends on the specific arrhythmia being treated and the cardiac condition of the mother and the foetus. Some antiarrhythmic agents, such as propranolol, metoprolol, digoxin and quinidine, have been extensively tested during pregnancy and have proven to be safe; they should therefore, whenever possible, be used as firstline. For supraventricular tachycardia, intravenous adenosine may be used to terminate the arrhythmia if vagal manoeuvres fail. In emergency situations cardioversion may be performed with relative safety. Implantable cardioverter defibrillators as a preventive measure for life-threatening arrhythmias in pregnant patients do not seem to increase the risk of major complications.

Adult↗
PubMed2000

DDD pacing mode survival in children with a dual-chamber pacemaker.

BACKGROUND: The persistence of DDD pacing is well documented in adults, however, in children survival of the DDD pacing mode is less clear. METHODS: We studied the survival of dual-chamber (DDD) pacing in 36 children aged 1 week to 16 years who underwent implantation of a dual-chamber pacing system between January 1986 and October 1998. The children were divided in the following two groups: 26 had epicardial pacing systems and 10 had endocardial pacing systems. RESULTS: During long-term follow-up 11 patients lost the DDD pacing mode. The DDD pacing survival rate at 3 months and 1, 2, and 5 years was 80%, 77%, 73%, and 69%, respectively. Age, weight, congenital heart disease, and epicardial pacing leads were not found to be risk factors for loss of DDD pacing mode. However, P-wave values of less than 2.5 mV at implantation of epicardial leads were associated with loss of the DDD pacing mode. CONCLUSIONS: The majority of children remain in the DDD pacing mode during long-term follow-up. A P-wave value of less than 2.5 mV at implantation of epicardial leads is a risk factor for loss of the DDD pacing mode.

Adolescent↗
PubMed2000

Threshold tracking pacing based on beat by beat evoked response detection: clinical benefits and potential problems.

Continuous monitoring of pacemaker stimulation thresholds and automatic adjustment of pacemaker outputs were among the longstanding goals of the pacing community. The first clinically successful implementation of threshold tracking pacing was the Autocapture feature which has accomplished automatic ventricular capture verification for every single stimulus by monitoring the Evoked Response (ER) signal resulting from myocardial depolarization. The Autocapture feature not only decreases energy consumption by keeping the stimulation output slightly above the actual threshold, but also increases patient safety by access to high-output back-up pulses if there is loss of capture. Furthermore, it provides valuable documentation of stimulation thresholds over time and serves as a valuable research tool. Current limitations for its widespread use include the requirements for implantation of bipolar low polarization leads and unipolar pacing in the ventricle. Fusion/pseudofusion beats with resultant insufficient or even non-existent ER signal amplitudes followed by unnecessary delivery of back-up pulses and a possible increase in pacemaker output is not an uncommon observation unique to the Autocapture feature. The recent incorporation of the Autocapture algorithm in dual chamber pacemakers has been challenging because of more frequent occurrence of fusion/pseudofusion beats in the presence of normal AV conduction. Along with a review of the previously published studies and our clinical experience, this article discusses the clinical advantages and potential problems of Autocapture.

Algorithms↗
PubMed2000

Autonomic effects of radiofrequency catheter ablation.

Radiofrequency (RF) catheter ablation has become the treatment of choice for a variety of supraventricular tachycardias. Autonomic dysfunction may occur during application of RF current; these abnormalities resolve quickly when current delivery is terminated. We present a case of sinus node arrest and AV block in a 69-year-old woman induced by RF catheter ablation of an AV nodal slow pathway. The proposed mechanisms are a Bezold-Jarisch-like phenomenon or paradoxical activation of cardiac C fibres by direct neural sympathetic stimulation or RF-induced myocardial injury. Based on a review of previously published reports, autonomic effects of RF ablation are discussed.

Aged↗
PubMed2000

Morphology discriminator feature for enhanced ventricular tachycardia discrimination in implantable cardioverter defibrillators.

The morphology discriminator (MD) feature is an electrogram template matching algorithm that intends to improve tachycardia discrimination in implantable cardioverter defibrillators (ICDs). The aim of this study was to evaluate the performance of this feature during spontaneously occurring ventricular and supraventricular tachyarrhythmias and exercise induced sinus tachycardia. Twenty-three patients (20 men, 3 women; mean age 54.3 +/- 13.8 years) with pectorally implanted Ventritex Contour MD, Angstrom MD, and Profile MD ICDs were studied. The stability of the acquired morphology template and performance of the algorithm during spontaneous tachyarrhythmias were evaluated at follow-up. A treadmill exercise test was performed in 16 patients along with continuous telemetric monitoring of matching scores. A satisfactory template could be acquired at baseline in 22 (96%) patients. Variations in electrogram morphology necessitated new template acquisition in seven (30%) patients at first follow-up (6-8 weeks postimplant). During a mean follow-up of 9.1 +/- 3.7 months, 56 ventricular tachycardia (VT) and 15 supraventricular tachycardia episodes (sinus tachycardia in two-thirds) in 11 patients were all appropriately discriminated by the MD feature. Exercise testing showed appropriate discrimination of sinus tachycardia in 15 (94%) of 16 patients. A common observation was postshock changes in electrogram morphology that resulted in transient mismatch with the template. In conclusion, the recently introduced MD feature in ICDs has a high sensitivity for detection of VT and high specificity for rejection of sinus tachycardia. Postshock changes in electrogram morphology have been observed that may cause inappropriate redetection. Marked variations of electrogram morphology over time may be a concern in some patients, especially during lead maturation.

Adult↗
PubMed1999

[Indications criteria for total cavopulmonary anastomosis (Fontan operation)].

OBJECTIVES: In a retrospective study we evaluated the predictive value of the traditional risk factors (Fontan criteria) for mortality and morbidity after total cavopulmonary anastomosis (Fontan operation). DESIGN: We studied 51 consecutive patients who underwent Fontan operations from 1982 through 1994. Morbidity was assessed by a score taking equally into account rhythm disturbances, cardiovascular hospital admissions and heart failure. RESULTS: The mean age at operation was 4.1 +/- 3.4 years. Diagnoses were tricuspid atresia in 20, complex single ventricle in 13 and various complex congenital heart defects in 18 patients. All Fontan criteria were fulfilled in 11 patients while in the remaining 40 up to 6 criteria were not met. The criteria least fulfilled were age in 31 patients and pulmonary artery anatomy in 11. The mean follow-up was 4.6 +/- 3.0 years. The overall 30-day survival was 84% and 1- and 10-year survival 76.5% respectively. All patients who fulfilled all the Fontan criteria survived. The overall mortality and early mortality were associated with a significantly higher number of unfulfilled Fontan criteria (p < 0.01). Age below 2 years at operation and pulmonary resistance > 4 Woods units were risk factors for overall mortality (p < 0.01). The number of unmet Fontan criteria was not significantly different in patients with and without postoperative late morbidity. CONCLUSIONS: The Fontan criteria are reliable predictors for mortality but have little predictive value for morbidity. Surviving patients who do not fulfil all criteria suggest that some criteria may need to be modified. Our limited data support a lower age limit of 2 instead of 4 years.

Adolescent↗
PubMed1999

Low-energy epicardial pacing in children: the benefit of autocapture.

BACKGROUND: Permanent cardiac pacing in children results commonly in augmented energy consumption because of the high pacing rates and the ample stimulation safety margin applied in children. Cardiovascular anatomy and limited venous access sometimes preclude the otherwise preferred endocardial approach. In this multicenter patient series, we studied the feasibility, safety, and energy saving obtained by a combination of steroid-eluting epicardial leads with autocapture devices capable of ongoing adjustment of the stimulation output to the prevailing threshold. METHODS: Autocapture devices (Pacesetter Microny SR+/- and Regency SR+/-; Pacesetter, Solna, Sweden) and steroid-eluting epicardial pacing leads (Medtronic CapSure Epi 10366; Medtronic, Inc, Minneapolis, MN) were implanted in 14 children. Thresholds, telemetry data, evoked response, and polarization signals were obtained at discharge and follow-up, and battery service life was calculated. RESULTS: During a median follow-up of 6.5 months, autocapture pacing was applied in 12 of 14 children. The automatically adjusted pulse amplitude of autocapture devices demonstrated low-energy pacing with no significant changes between discharge and 6 months follow-up (1.1 +/- 0.3 versus 0.9 +/- 0.3 V). Autocapture-programmed pacemakers had calculated life spans of 7.8 +/- 1.4 years (Microny) and 21.0 +/- 1.6 years (Regency). No adverse effects were noted. CONCLUSIONS: Autocapture-controlled pacing with bipolar epicardial pacing leads is feasible and safe in children. Autocapture programming results in substantial energy savings and extends battery life markedly.

Child↗
PubMed1999

Myocardial ischaemia in children with isolated ventricular non-compaction.

AIMS: Isolated ventricular non-compaction is a rare congenital cardiomyopathy with a high morbidity and mortality due to malignant arrhythmias and pump failure. Areas affected by non-compaction are characterized by increased trabecularization and deep inter-trabecular spaces. We hypothesized perfusion defects in these areas and performed positron emission tomography to evaluate the myocardial perfusion in non-compacted areas. METHODS AND RESULTS: Five children (age 10-14 years) with isolated ventricular non-compaction underwent positron emission tomography using N-13-ammonia as flow marker and intravenous dipyridamole for stress testing. Myocardial blood flow was quantified using the positron emission tomography time-activity curves in non-compacted areas and normal myocardium, which were diagnosed by echocardiography, magnetic resonance imaging, and angiography. Coronary angiography, performed in two children with extensive forms of left ventricular non-compaction, demonstrated normal coronary arteries. Myocardial blood flow measurements at rest and after dipyridamole application demonstrated 16-33% and 32-57% perfusion impairment, respectively, in non-compacted areas compared to normal myocardium. Areas of restricted myocardial perfusion corresponded well to the non-compacted areas, defined echographically and by magnetic resonance imaging. CONCLUSION: Positron emission tomography demonstrates restricted myocardial perfusion and decreased flow reserve in areas of ventricular non-compaction in children. The myocardial perfusion defects in non-compacted areas may be the cause of myocardial damage and possibly form the basis of arrhythmias and pump failure.

Adolescent↗
PubMed1998

Myocarditis and coronary dilatation in the 1st week of life: neonatal incomplete Kawasaki disease?

UNLABELLED: Acute heart failure in the early neonatal period is rare. Normally it is due to asphyxia, severe septicaemia, a congenital heart malformation or a viral myocarditis. Kawasaki disease (KD) as a cause of an neonatal myocarditis is not an established diagnosis. KD is a vasculitis of still unknown origin occurring predominantly in infants and preschool children. KD before the age of 3 months is rare. There are only few reports about KD in the 1st month. We present a newborn who showed the cardiac symptoms of KD in the 1st week of life with coronary dilatation and myocarditis. CONCLUSION: The diagnosis of incomplete KD should be considered not only in infants but also in newborns with signs of myocarditis and coronary abnormalities. Therapy with gammaglobulins may prevent the sequelae of coronary involvement.

Coronary Disease↗