Biomedical subjects

E Hoffmann

Publications and source records attributed to E Hoffmann.

At least 55 records · Page 3Linked to original sources

PubMed2001

Laser ablation inductively coupled plasma mass spectrometry: a new tool for trace element analysis in ice cores.

A new method for the detection of trace elements in polar ice cores using laser ablation with subsequent inductively coupled plasma mass spectrometry analysis is described. To enable direct analysis of frozen ice samples a special laser ablation chamber was constructed. Direct analysis reduces the risk of contamination. The defined removal of material from the ice surface by means of a laser beam leads to higher spatial resolution (300-1000 microm) in comparison to investigations with molten ice samples. This is helpful for the detection of element signatures in annual layers of ice cores. The method was applied to the successful determination of traces for the elements Mg, Al, Fe, Zn, Cd, Pb, some rare-earth elements (REE) and minor constituents such as Ca and Na in ice cores. These selected elements serve as tracer elements for certain sources and their element signatures detected in polar ice cores can give hints to climate changes in the past. We report results from measurements of frozen ice samples, the achievable signal intensities, standard deviations and calibration graphs as well as the first signal progression of 205Pb in an 8,000-year-old ice core sample from Greenland. In addition, the first picture of a crater on an ice surface burnt by an IR laser made by cryogenic scanning electron microscopy is presented.

Journal Article↗

PubMed2001

Universal primer set for the full-length amplification of all influenza A viruses.

To systematically identify and analyze the 15 HA and 9 NA subtypes of influenza A virus, we need reliable, simple methods that not only characterize partial sequences but analyze the entire influenza A genome. We designed primers based on the fact that the 15 and 21 terminal segment specific nucleotides of the genomic viral RNA are conserved between all influenza A viruses and unique for each segment. The primers designed for each segment contain influenza virus specific nucleotides at their 3'-end and non-influenza virus nucleotides at the 5'-end. With this set of primers, we were able to amplify all eight segments of N1, N2, N4, N5, and N8 subtypes. For N3, N6, N7, and N9 subtypes, the segment specific sequences of the neuraminidase genes are different. Therefore, we optimized the primer design to allow the amplification of those neuraminidase genes as well. The resultant primer set is suitable for all influenza A viruses to generate full-length cDNAs, to subtype viruses, to sequence their DNA, and to construct expression plasmids for reverse genetics systems.

Child↗

PubMed2001

Early reinitiation of atrial fibrillation following external electrical cardioversion in amiodarone-treated patients.

UNLABELLED: Early reinitiation of atrial fibrillation (ERAF) following external or internal electrical cardioversion is one of the factors determining unsuccessful electrical cardioversion. Prevention of ERAF has not been studied systematically in patients on amiodarone therapy. METHODS AND RESULTS: 22 patients had ERAF within 1 min after external electrical cardioversion of atrial fibrillation. 11 patients were on amiodarone therapy and 11 patients had no antiarrhythmic medication. The effect of atropine, post-shock atrial pacing and intravenous ajmaline on ERAF was consecutively tested in these patients. Administration of atropine before repeated defibrillation or post-shock atrial pacing prevented ERAF in 9 of the 11 patients (82%) on amiodarone therapy but in only 3 of 11 patients (27%) without amiodarone (p<0.05). In the remaining patients, intravenous ajmaline was effective in the suppression of ERAF in 5 patients without amiodarone and in 1 patient with amiodarone. The PP interval preceding the atrial premature beat reinitiating atrial fibrillation was nonsignificantly longer in amiodarone-treated patients (1127+/-419 ms) in comparison to patients without amiodarone (896+/-271ms). 27% of patients without amiodarone at the time of electrical cardioversion and 55% of patients with amiodarone remained in sinus rhythm during the follow-up of 29+/-14 and 30+/-14 months, respectively. CONCLUSIONS: ERAF in patients on amiodarone can be treated by atropine or atrial pacing to prevent bradycardia-dependent ERAF. ERAF in amiodarone-treated patients does not apparently predict late recurrence of atrial fibrillation on continued amiodarone therapy.

Adult↗

PubMed2001

Electroanatomical mapping for visualization of atrial activation in patients with incisional atrial tachycardias.

AIMS: Incisional atrial tachycardias in patients following surgery for congenital heart disease are based on complex structural abnormalities in these hearts. The aim of this study was to evaluate the use of the electroanatomical mapping system, CARTO, in consecutive patients with different forms of incisional atrial tachycardia. METHODS AND RESULTS: The electroanatomical mapping system combines electrophysiological and spatial information and allows visualization of atrial activation in a three-dimensional anatomical reconstruction of the atria. Electroanatomical mapping of right atrial activation was performed in 10 patients after surgery for congenital heart disease, surgery for Wolff-Parkinson-White syndrome, or heart transplantation presenting with 13 incisional atrial tachycardias. The three-dimensional mapping allowed a rapid distinction between focal (n=3) and reentrant mechanisms (n=10) and visualization of the activation wavefronts along anatomical and surgically created barriers. Electroanatomical activation maps (mean right atrial activation time 213+/-107 ms) were constructed with 89+/-60 catheter positions during an average mapping time of 48+/-33 min. Reentrant tachycardias propagating through the tricuspid annulus-vena cava inferior isthmus (n=6) or along periatriotomy loops (n=4) were identified in eight patients. Ectopic atrial foci near surgical scars could be localized in three patients. Catheter ablation by creation of a lesion in a critical isthmus of conduction or by targeting the arrhythmogenic focus eliminated 11 of 13 incisional atrial tachycardias. CONCLUSION: Visualization of atrial activation in a three-dimensional reconstruction of the right atrium using the electroanatomical mapping system CARTO facilitates understanding of the mechanism and defines the reentrant circuits of incisional atrial tachycardias. This new method may improve the success rate of electrophysiologically guided and anatomically guided catheter ablation of incisional atrial tachycardias.

Adult↗

PubMed2001

XML-based visual data mining in medicine.

Medical databases in general are characterized by a high degree of complexity in terms of quantity of items, number of parameter values and data types (free text, categorical, numerical and other). Substantial domain knowledge is required for adequate formalization of medical entities. In this context we developed medical database plot (mdplot), a data mining tool to visualize both structure and quality of data in medical databases to identify items suitable for evaluation. Data models are provided in XML format. Missing data is identified to enable targeted efforts to improve data quality prior to analysis. Database items are classified as 1:1- related to the patient (i.e. variables are collected once per patient) and 1:n related. mdplot provides a list of all classes contained in a database, the number of records each and a condensed bar chart for semi-quantitative description of completeness according to four types of items: categorical, numerical, text and other. All items in a category are grouped from left to right, the height of each bar represents the proportion of non-missing values with respect to the total number of records in the class; thus the amount of content in a specific class is visualized. By selection of a specific class, a detailed description of it is provided including mean completeness in each item category as well as number of values per item. The new methodology was applied to a cardiological research database consisting of 619 items on 88 patients.

Atrial Fibrillation↗

PubMed2001

Identification of pharmaceutical glasses by laser ablation ICP-MS.

The chemical composition of pharmaceutical glasses (ampoules, infusion bottles, plunger) has been determined by laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). A Nd:YAG laser with 10 Hz repetition rate in the Q-switch mode at its fundamental wavelength (1064 nm) was used to identify common types of pharmaceutical glasses. The following isotopes were used for measurements: 7Li, 11B, 23Na, 24Mg, 27Al, 28Si, 29Si, 30Si, 39K, 42Ca, 47Ti, 57Fe, 90Zr, 121Sb, 137Ba. Each analysis included the measurement of 12 craters. Relative standard deviations between 1.8% and 8.0% of the quantitative results were obtained. 29Si was used as internal standard. Standard reference materials (soda-lime-, lead- and borosilicate glasses) were used for external calibration of laser sampling. Linear calibration functions for each isotope were found. All samples and standard materials were digested in a two-step-procedure by nitric/fluoric acid, then measured and externally calibrated by ICP-MS with multi-elemental standard solutions using 45Sc as internal standard. Digestion and laser ablation results agree within 8% (confidential interval 95%) with the certified values. Intensity ratios of most isotopes also agree sufficiently with the corresponding theoretical values (+/- 18%). The developed method allows to distinguish different types of pharmaceutical glasses.

Calibration↗

PubMed2000

Efficient expression of the tumor-associated antigen MAGE-3 in human dendritic cells, using an avian influenza virus vector.

Dendritic cells (DCs) are the most potent inducers of immune reactions. Genetically modified DCs, which express tumor-associated antigens (TAA), can efficiently induce antitumor immunity and thus have a high potential as tools in cancer therapy. The gene delivery is most efficiently achieved by viral vectors. Here, we explored the capacity of influenza virus vectors to transduce TAA genes. These viruses abortively infect DCs without interfering with their antigen-presenting capacity. In contrast to other viruses used for DC transduction, influenza viruses can be efficiently controlled by antiviral pharmaceuticals, lack the ability to integrate into host chromosomes, and fail to establish persistent infections. Genes encoding a melanoma-derived TAA (MAGE-3), or the green fluorescence protein (GFP), were introduced into a high-expression avian influenza virus vector. Monocyte-derived mature DCs infected by these recombinants efficiently produced GFP or MAGE-3. More than 90% of the infected DCs can express a transduced gene. Importantly, these transduced DCs retained their characteristic phenotype and their potent allogeneic T cell stimulatory capacity, and were able to stimulate MAGE-3-specific CD8(+) cytotoxic T cells. Thus influenza virus vectors provide a highly efficient gene delivery system in order to transduce human DCs with TAA, which consequently stimulate TAA-specific T cells.

Animals↗

PubMed2000

Regional and cellular induction of nicotine-metabolizing CYP2B1 in rat brain by chronic nicotine treatment.

In the rat, nicotine is metabolized to cotinine primarily by hepatic cytochrome P450 (CYP) 2B1. This enzyme is also found in other organs such as the lung and the brain. Hepatic nicotine metabolism is unaltered after nicotine exposure; however, nicotine may regulate CYP2B1 in other tissues. We hypothesized that nicotine induces its own metabolism in brain by increasing CYP2B1. Male rats were treated with nicotine (0.0, 0.1, 0.3, or 1.0 mg base/kg in saline) s.c. daily for 7 days. CYP2B1 mRNA and protein were assayed in the brain and liver by reverse transcriptase-polymerase chain reaction (RT-PCR), immunoblotting, and immunocytochemistry. In control rats, CYP2B1 mRNA and protein expression were brain region- and cell-specific. CYP2B1 was not induced in the liver, but CYP2B1 mRNA and protein showed dose-dependent, region- and cell-specific patterns of induction across brain regions. At 1.0 mg nicotine/kg, the largest increase in protein was in the brain stem (5.8-fold, P < 0.05) with a corresponding increase in CYP2B1 mRNA (7.6-fold, P < 0.05). Induction of CYP2B1 was also observed in the frontal cortex, striatum, and olfactory tubercle. Immunocytochemistry showed that induction was restricted principally to neurons. These data indicate that nicotine may alter its own metabolism in the brain through transcriptional regulation, perhaps contributing to central tolerance to the effects of nicotine. CYP2B1 and its human homologue CYP2B6 also activate tobacco smoke procarcinogens such as NNK [4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone]. Highly localized increases in CYP2B could result in increased mutagenesis. These data suggest roles for nicotine-induced CYP2B in central metabolic tolerance, nicotine-induced neurotoxicity, neuroplasticity, and carcinogenesis.

Animals↗

PubMed2000

A DNA transfection system for generation of influenza A virus from eight plasmids.

We have developed an eight-plasmid DNA transfection system for the rescue of infectious influenza A virus from cloned cDNA. In this plasmid-based expression system, viral cDNA is inserted between the RNA polymerase I (pol I) promoter and terminator sequences. This entire pol I transcription unit is flanked by an RNA polymerase II (pol II) promoter and a polyadenylation site. The orientation of the two transcription units allows the synthesis of negative-sense viral RNA and positive-sense mRNA from one viral cDNA template. This pol I-pol II system starts with the initiation of transcription of the two cellular RNA polymerase enzymes from their own promoters, presumably in different compartments of the nucleus. The interaction of all molecules derived from the cellular and viral transcription and translation machinery results in the generation of infectious influenza A virus. The utility of this system is proved by the recovery of the two influenza A viruses: A/WSN/33 (H1N1) and A/Teal/HK/W312/97 (H6N1). Seventy-two hours after the transfection of eight expression plasmids into cocultured 293T and MDCK cells, the virus yield in the supernatant of the transfected cells was between 2 x 10(5) and 2 x 10(7) infectious viruses per milliliter. We also used this eight-plasmid system for the generation of single and quadruple reassortant viruses between A/Teal/HK/W312/97 (H6N1) and A/WSN/33 (H1N1). Because the pol I-pol II system facilitates the design and recovery of both recombinant and reassortant influenza A viruses, it may also be applicable to the recovery of other RNA viruses entirely from cloned cDNA.

Animals↗

PubMed2000

Heart rate dynamics at the onset of ventricular tachyarrhythmias as retrieved from implantable cardioverter-defibrillators in patients with coronary artery disease.

BACKGROUND: The recent availability of implantable cardioverter-defibrillators (ICDs) that record 1024 R-R intervals preceding a ventricular tachyarrhythmia (VTA) provides a unique opportunity to analyze heart rate variability (HRV) before the onset of VTA. METHODS AND RESULTS: Fifty-eight post-myocardial infarction patients with an implanted ICD for recurrent VTA provided 2 sets of 98 heart rate recordings in sinus rhythm: (1) before a VTA and (2) during control conditions. Three subgroups were considered according to the antiarrhythmic (AA) drug regimen. A state of sympathoexcitation was suggested by the significant reduction in HRV before VTA onset compared with control conditions. beta-Blockers and dl-sotalol enhanced HRV in control recordings; nevertheless, HRV declined before VTA independent of AA drugs. A gradual increase in heart rate and decrease in sinus arrhythmia at VTA onset were specific findings of patients who received dl-sotalol. CONCLUSIONS: The peculiar heart rate dynamics observed before VTA onset are suggestive of a state of sympathoexcitation that is independent of AA drugs.

Adrenergic beta-Antagonists↗

PubMed2000

"Ambisense" approach for the generation of influenza A virus: vRNA and mRNA synthesis from one template.

We present a system for creating influenza virus by generating viral RNA (vRNA) and mRNA from one template. Recently, a system for the generation of influenza A virus entirely from cloned cDNAs was established (Neumann et al., 1999, Proc. Natl. Acad. Sci. USA 96, 9345-9350). Cells were transfected with plasmids for RNA polymerase I-driven intracellular synthesis of all eight viral RNAs, and with protein expression plasmids for the synthesis of viral structural proteins. Although this system is highly efficient in virus generation, the construction and cotransfection of 17 plasmids is cumbersome and may limit the use of this system to cell lines that can be transfected with high efficiencies. Synthesizing both vRNA and mRNA from one template would reduce the number of plasmids required for virus generation. Therefore, we generated a bidirectional transcription construct that contains cDNA encoding PB1 flanked by an RNA polymerase I (pol I) promoter for vRNA synthesis and an RNA polymerase II (pol II) promoter for mRNA synthesis. The utility of this approach is proved by the generation of virus after transfecting the pol I/pol II-promoter-PB1 construct together with vRNA- and protein-expression constructs for the remaining seven segments. Because this approach reduces the number of plasmids required for virus generation, it also reduces the work necessary for cloning, probably enhances the efficiency of virus generation, and expands the use of the reverse-genetics system to cell lines for which efficient cotransfection of 17 plasmids cannot be achieved.

Animals↗

PubMed2000

Effects of intra-accumbens injection of 2-methylthio ATP: a combined open field and electroencephalographic study in rats.

RATIONALE: Previous experiments have shown that P2 receptor activation increases the release of dopamine in the mesolimbic mesocortical system. OBJECTIVE: In order to investigate the functional correlates of dopaminergic stimulation, EEG and behavioural responses to injection of the P2 receptor agonist 2-methylthio ATP (2-MeSATP) into the nucleus accumbens (NAc) of rats were investigated. METHODS: EEG electrodes were positioned into the NAc together with the guide cannula for intracerebral injection. Behavioural analysis was performed in an open field cage and was evaluated by a video activity measurement system. Rats were assigned to separate groups that were given artificial cerebrospinal fluid (aCSF) or drug treatment. RESULTS: 2-MeSATP significantly extended the period of locomotor activity in the novel environment. The quantitative EEG was characterized by an elevation of the power in the alpha-range and a decrease in power in the delta range. The P2 receptor antagonists reactive blue 2 but not pyridoxalphosphate-6-azophenyl-2'4'-disulphonic acid (PPADS) also enhanced locomotion when given alone, and elevated the alpha-1 and beta-2 bands. Both antagonists abolished the locomotor and EEG responses to 2-MeSATP. The dopamine D1 receptor antagonist SCH 23390 and the D2/D3 receptor antagonist sulpiride did not alter locomotor activity when given either alone or in combination. Only sulpiride and especially sulpiride in combination with SCH 23390 prevented the effect of 2-MeSATP. Sulpiride produced a selective increase in the alpha-1 band of the power spectrum whereas SCH 23390 elevated the power of the alpha-1, alpha-2 and beta-1 activities. Neither antagonist inhibited the effect of 2-MeSATP on the EEG when applied separately; however, the co-administration of SCH 23390 and sulpiride abolished the 2-MeSATP-induced alteration of power distribution. After a 6-hydroxydopamine (6-OHDA)-induced lesion of the accumbal dopaminergic terminals, 2-MeSATP failed to enhance the locomotor activity and to induce the characteristic EEG changes. CONCLUSIONS: The observed alterations in open field behaviour and quantitative EEG after injection of 2-MeSATP into the NAc may be mostly due to P2 receptor-mediated dopamine release and subsequent receptor activation.

Adenosine Triphosphate↗

PubMed2000

Spatial determination of elements in green leaves of oak trees (Quercus robur) by laser ablation-ICP-MS.

Laser ablation inductively coupled plasma mass spectrometry (laser ablation-ICP-MS) has been applied to the spatially resolved determination of the elements Mg, Ca, Cu, Ni, Ba, Al, Pb, Sr and Mn in green leaves of oak trees. Instrument operating parameters such as the laser wavelength and the pulse energy have been optimized to provide the sensitivity and reproducibility required for the analysis. The method provides spatial resolution down to 300 microm with the use of the 355 nm wavelength (3rd harmonic of the 1,064 nm Nd:YAG laser wavelength) and the pulse energy of 50 mJ. Plant standards and cellulose, doped with multi element solution standards, dried and pressed to pellets were used as calibration samples. To compensate for signal fluctuations caused by the variation of the ablated sample mass 13C was used as a "natural" internal standard. The accuracy of the calibration was verified with selected samples analyzed by ICP-MS (high pressure digestion, 170 degrees C, 10(7) Pa, HNO3, 2 h) and by laser ablation-ICP-MS. Recovery rates between 93% (Cu) and 108% (Mn) were obtained. Leaves taken from oak trees (Quercus robur) were analyzed.

Calibration↗

PubMed2000

Solar blind photocell--a simple element specific detector in Hg, As and Se speciation.

An element-specific detection method, based on atomic absorption spectrometry (AAS) using solar blind photocells instead of a dispersion system, is described for the determination of Hg-, As-, and Se-species. Spectrometric investigations of AAS background lamps for As and Se measured with a CsI-cathode photocell shows its quality as narrow band detector. Species determination can be carried out subsequently to prior separation by HPLC or GC. The LODs for alkylated Hg species were below 1 ng/L, and for methylated As species below 1 microg/L. The relative standard deviation was < 10%. With the components described the production of cheap and automated dedicated speciation spectrometers is possible.

Journal Article↗

PubMed2000

[Variable late potentials in long-term ECG of the post-infarct patient at risk for ventricular fibrillation].

BACKGROUND: Ventricular late potentials are found more readily in post-infarction patients who had sustained ventricular tachycardia than in those who survived ventricular fibrillation. Hypothetically, a daytime variability of late potentials might be responsible for this finding. METHOD: Therefore a conventional late potential analysis only performed once a day was compared to a late potential analysis in time and frequency domain repeatedly performed every hour in the Holter-ECG of 160 post-infarction patients (50 patients (= VT-group) with documented, sustained ventricular tachycardia (cycle-length > 230 ms), 50 patients (= VF-group) who survived, documented ventricular fibrillation and 60 patient, without ventricular arrhythmias (= O VT/VF-group)). RESULTS: The conventional analysis showed late potentials in time domain in 72% of the patients in the VT-group, in 40% of patients in the VF-group and in 20% of the patients in the O VT/VF-group. The Holter-ECG showed late potentials to be permanently present in frequency domain in 66% of the patients in the VT-group, in only 6% in the patients in the VF-group and in no patient in the O VT/VF-group. However, in at least one analysis we detected late potentials in 84% of patients of the VF-group, in 90% of patients in the VT-group and in 18% of patients in the O VT/VF-group. Transiently detectable late potentials in patients of the VF-group were predominantly seen at heart rate accelerations in the morning hours, ST-segment shifts or transitory decreased heart rate variability. CONCLUSIONS: Post-infarction patients with sustained ventricular tachycardia predominantly have constantly detectable late potentials over 24 hours. In these patients conventional late potential is successful for post-infarction risk stratification at any time of the day. However, in post-infarction patients who survived ventricular fibrillation, late potentials are found to be transitory and only detectable by Holter-ECG. Thus, late potential analysis performed in the Holter-ECG might improve post-infarction risk stratification in patients prone to sudden cardiac death.

Aged↗

PubMed2000

Amiodarone: maximising survival benefit with empiric or guided therapy.

Review of available data suggests that serial drug testing in patients with a history of sustained ventricular tachyarrhythmias using various antiarrhythmic drugs including amiodarone is able to identify subgroups with favorable and unfavorable outcome (patient groups with suppression vs. no suppression of inducibility of VT/VF). These results more likely reflect patient selection rather than drug effects, thus limiting the role of electrophysiologically guided antiarrhythmic therapy to actively modify outcome. All major and actual antiarrhythmic drug trials including an amiodarone arm, have chosen to deliver this drug empirically in both patients with asymptomatic as well as severely symptomatic life-threatening sustained ventricular tachyarrhythmias instead of a guided approach. The empiric approach is therefore adequate until new valid data comparing the empiric with the guidedor the invasive with the non invasiveapproach tell us otherwise.

Amiodarone↗

PubMed2000

New mapping technology for atrial tachycardias.

UNLABELLED: Prerequisite for succesful radiofrequency catheter ablation of tachycardias is the exact mapping during the electrophysiological study. The new mapping system CARTO allows a three-dimensional color-coded electroanatomic map of impulse propagation using electromagnetic technology. The aim of this study was to determine the feasibility and safety of the new electromagnetic mapping technology CARTO for atrial tachycardias. RESULTS: Electrophysiologic study and CARTO mapping was performed in 38 atrial tachycardias. The mapping procedure took 26 +/- 23 min. We created 33 maps within the right atrium and 5 maps within the left atrium with a mean of 74 +/- 38 different catheter positions. The mechanism was determined as reentrant in 9, junctional in 1 and focal in 28 tachycardias. In focal tachycardias the tachycardia cycle length (CL) and the total atrial activation time (AT) were clearly different (352 +/- 98 ms vs 99 +/- 25 ms). Reentrant tachycardias had a comparable CL and AT (236 +/- 44 ms vs 240 +/- 56 ms). In 83% of the focal tachycardias and in 67% of the reentrant tachycardias, ablation was performed successfully. No complications occured. CONCLUSION: The electroanatomic mapping system allows high resolution visualization of electrical activity and may therefore improve precision and simplify the determination of the arrhythmogenic substrate during tachycardias for successful catheter ablation.

Adult↗

PubMed2000

Catheter ablation of atrial flutter due to amiodarone therapy for paroxysmal atrial fibrillation.

AIMS: Antiarrhythmic drug treatment for atrial fibrillation can cause atrial flutter-like arrhythmias. The aim of this study was to clarify the effect of catheter ablation of the tricuspid annulus-vena cava inferior isthmus on amiodarone-induced atrial flutter and to determine the incidence of atrial fibrillation after catheter ablation of amiodarone-induced atrial flutter in comparison to regular typical flutter. METHODS AND RESULTS: Among 92 consecutive patients with typical atrial flutter who underwent isthmus ablation 28 patients had atrial flutter without a history of previous atrial fibrillation (group I), 10 patients had atrial flutter following the initiation of amiodarone therapy for paroxysmal atrial fibrillation (group II) and 54 patients had atrial flutter and atrial fibrillation (group III). Atrial cycle length during atrial flutter in amiodarone-treated patients (group II) (277+/-24 ms) was significantly longer as compared to the cycle length of atrial flutter in group I (247+/-33 ms) and group III patients (235+/-28 ms). The rate of successful transient entrainment and overdrive stimulation to sinus rhythm was not different between patients with (60%) or without amiodarone therapy (group I: 71%, group III: 53%). Successful isthmus ablation with bidirectional conduction block eliminating right atrial flutter was achieved in 90% of amiodarone-treated patients and 93% of patients without amiodarone therapy. In the amiodarone-treated patient group atrial conduction times during pacing in sinus rhythm were significantly prolonged by 20-30% before and after ablation in all regions of the reentrant circuit. During a mean follow-up of 8+/-3 months post-ablation, atrial fibrillation recurred in two of 10 patients on continued amiodarone therapy after successful isthmus ablation. Thus, successful catheter ablation of atrial flutter due to amiodarone therapy was associated with a markedly lower recurrence rate of paroxysmal atrial fibrillation (20%) as compared to patients with atrial flutter plus preexisting paroxysmal atrial fibrillation (76%) and was similar to the outcome of patients with successful atrial flutter ablation without preexisting atrial fibrillation (25%). CONCLUSION: These data suggest that isthmus ablation with bidirectional block and continuation of amiodarone therapy is an effective therapy for the treatment of atrial flutter due to amiodarone therapy for paroxysmal atrial fibrillation.

Adult↗