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Biomedical subjects

F Hintringer

Publications and source records attributed to F Hintringer.

At least 19 recordsLinked to original sources
PubMed2006

Electromechanical synchronization of the heterotopic and native heart by dual atrial stimulation following heart transplantation.

After heterotopic heart transplantation, a 59-year-old woman presented with remarkable symptoms of breathlessness and fatigue, despite excellent donor heart function. Asynchrony of donor and native heart provoked haemodynamic instability. Dual atrial pacemaker implantation lead to linkage and synchronization of atrial and ventricular contraction in both the donor and native heart with the faster organ executing the synchronization. Remarkable relief of symptoms has been evident during the long-term follow-up.

Arrhythmia, Sinus↗
PubMed2005

Psychometric properties of an established heart disease specific health-related quality of life questionnaire for pacemaker patients.

Little is known about the HRQL of pacemaker patients due to the limited availability of disease-specific instruments. The aim of the Pacemaker Patients Quality of Life (PAPQoL) study was to determine the psychometric properties for the MacNew Heart Disease Health-related Quality of Life Questionnaire (MacNew) in patients before and after pacemaker implantation. Patients with a given indication for pacemaker therapy (N = 68) completed two self-administered HRQL instruments, the SF-36, a well-known and psychometrically sound health survey, and the MacNew, a reliable and valid heart-disease-specific HRQL instrument, before and one, three and six months after pacemaker implantation. We assessed disease severity with the New York Heart Association (NYHA) classification. Test-retest reliability, intra-class correlation, Cronbach's alpha, validity coefficients, sensitivity analyses (effect sizes) and confirmatory factor analysis were carried out. The MacNew demonstrated adequate reliability (Cronbach's alpha and ICCs > 0.80 on all scales), validity (correlations between similar SF-36 and MacNew subscales > 0.80), and responsiveness (all effect sizes > or = 0.67) in pacemaker patients. The MacNew demonstrates adequate psychometric properties for evaluating HRQL in patients before and after pacemaker implantation.

Aged↗
PubMed2005

A signal processing pipeline for noninvasive imaging of ventricular preexcitation.

OBJECTIVES: Noninvasive imaging of the cardiac activation sequence in humans could guide interventional curative treatment of cardiac arrhythmias by catheter ablation. Highly automated signal processing tools are desirable for clinical acceptance. The developed signal processing pipeline reduces user interactions to a minimum, which eases the operation by the staff in the catheter laboratory and increases the reproducibility of the results. METHODS: A previously described R-peak detector was modified for automatic detection of all possible targets (beats) using the information of all leads in the ECG map. A direct method was applied for signal classification. The algorithm was tuned for distinguishing beats with an adenosine induced AV-nodal block from baseline morphology in Wolff-Parkinson-White (WPW) patients. Furthermore, an automatic identification of the QRS-interval borders was implemented. RESULTS: The software was tested with data from eight patients having overt ventricular preexcitation. The R-peak detector captured all QRS-complexes with no false positive detection. The automatic classification was verified by demonstrating adenosine-induced prolongation of ventricular activation with statistical significance (p <0.001) in all patients. This also demonstrates the performance of the automatic detection of QRS-interval borders. Furthermore, all ectopic or paced beats were automatically separated from sinus rhythm. Computed activation maps are shown for one patient localizing the accessory pathway with an accuracy of 1 cm. CONCLUSIONS: The implemented signal processing pipeline is a powerful tool for selecting target beats for noninvasive activation imaging in WPW patients. It robustly identifies and classifies beats. The small beat to beat variations in the automatic QRS-interval detection indicate accurate identification of the time window of interest.

Action Potentials↗
PubMed2005

Computationally efficient noninvasive cardiac activation time imaging.

OBJECTIVE: The computer model-based computation of the cardiac activation sequence in humans has been recently subject of successful clinical validation. This method is of potential interest for guiding ablation therapy of arrhythmogenic substrates. However, computation times of almost an hour are unattractive in a clinical setting. Thus, the objective is the development of a method which performs the computation in a few minutes run time. METHODS: The computationally most expensive part is the product of the lead field matrix with a matrix containing the source pattern on the cardiac surface. The particular biophysical properties of both matrices are used for speeding up this operation by more than an order of magnitude. A conjugate gradient optimizer was developed using C++ for computing the activation map. RESULTS: The software was tested on synthetic and clinical data. The increase in speed with respect to the previously used Fortran 77 implementation was a factor of 30 at a comparable quality of the results. As an additional finding the coupled regularization strategy, originally introduced for saving computation time, also reduced the sensitivity of the method to the choice of the regularization parameter. CONCLUSIONS: As it was shown for data from a WPWpatient the developed software can deliver diagnostically valuable information at a much shorter span of time than current clinical routine methods. Its main application could be the localization of focal arrhythmogenic substrates.

Arrhythmias, Cardiac↗
PubMed2004

Ventricular surface activation time imaging from electrocardiogram mapping data.

Non-invasive imaging of cardiac electrophysiology provides a non-invasive way of obtaining information about electrical excitation. An iterative algorithm based on a general regularisation scheme for non-linear, ill-posed problems in Hilbert scales was applied to the electrocardiographic inverse problem, imaging the ventricular surface activation time (AT) map. This method was applied to electrocardiographic data from a 31-year-old healthy volunteer and a 24-year-old patient suffering from a Wolff-Parkinson-White (WPW) syndrome. The objective was to evaluate non-invasive AT imaging of an autonomous sinus rhythm and to quantify the localisation error of non-invasive AT imaging by localising the accessory pathway of the WPW syndrome and a pacing site for left ventricle pacing. The distances between the invasive and non-invasive localisation of the pacing site and the accessory pathway were 8 mm and 5 mm. The clinical case presented, shows that this non-invasive AT imaging approach may enable the reconstruction of single focal events with sufficient accuracy for potential clinical application.

Adult↗
PubMed2004

Reduction of the pace polarization artefact for capture detection applications by a tri-phasic stimulation pulse.

This study investigated the ability to minimize pace polarization artefacts (PPA) by adjusting the post-stimulus pulse duration of a tri-phasic stimulation pulse. Adjustment of the stimulation pulse was enabled by downloading special study software into an already implanted pacemaker. Tests were performed in a total of 296 atrial leads and 311 ventricular leads. Both chronic and acute leads were included in the study. Statistically significant differences were found in the initial PPA (without any adjustment of the stimulus pulse) between atrial and ventricular leads. In addition, significant differences were observed among various lead models with respect to changes over time in the initial ventricular PPA. Successful PPA reduction was defined as a reduction of the PPA below 0.5 mV for atrial leads and below 1 mV for ventricular leads. Results show a success rate for ventricular and atrial PPA reduction of 97.8% and 98.7%, respectively. Threshold tests showed that after reduction of the PPA loss of ventricular capture can be reliably detected. However, atrial threshold tests showed many false positive evoked response detections. In addition, unexpectedly high evoked response amplitudes were observed in the atrium after reduction of the PPA. Results from additional measurements suggest that these high atrial evoked response amplitudes come from the influence of the input filter of the pacemaker.

Aged↗
PubMed2001

Mouse model of myocardial remodelling after ischemia: role of intercellular adhesion molecule-1.

OBJECTIVE: We studied the effects of temporary myocardial ischemia and reperfusion on myocyte injury and ventricular remodelling in wildtype and intercellular adhesion molecule-1- (ICAM-1) deficient mice. METHODS: ICAM-1-/- and ICAM-1+/+ mice were subjected to 30 min of myocardial ischemia and subsequent reperfusion for 2 h, 1 week and 3 weeks, respectively. The evaluation of tissue damage and scar size was performed with histological sections stained with hematoxilin and eosin. Serum levels of troponin T, creatine kinase and lactate dehydrogenase isoenzyme 1 were evaluated as an index of cardiac cellular damage. Immunohistological analysis was employed to determine cell compositions in ischemic regions. RESULTS: After myocardial ischemia (30 min) and 2 h reperfusion, elevation in serum troponin T, creatine kinase and lactate dehydrogenase isoenzyme 1 were found in both groups, but significantly reduced in ICAM-1-/- mice compared with wildtype mice (P<0.05). Absence of a functional ICAM-1 gene in ICAM-1-/- mice resulted in a marked reduction of ischemia-reperfusion injury at the early stage. The damage score and size of the infarct area were lower in ICAM-1 -/- mice by 30 min of ischemia and 2 h of reperfusion (1.4+/-0.54 vs. 2.4+/-0.47, P<0.05). The percentage of MAC-1-positive cells in the ischemic region and the border zone was also significantly diminished in groups of ICAM-1-/- mice. Surprisingly, the scar size in ventricles in animals 1 or 3 weeks after ischemia was similar between ICAM-1-/- and ICAM-1+/+ mice, although the number of infiltrated MAC-1 positive cells in the scar in wildtype mice was higher. CONCLUSION: Our results demonstrate that the absence of ICAM-1 expression results in less myocardial damage induced by ischemia-reperfusion at the early stage, but does not influence the size of myocardial infarction and scar formation.

Animals↗
PubMed2001

The effect of the atrial pacing site on the total atrial activation time.

The effect of dual site pacing for prevention of atrial fibrillation may be due to synchronization of right and left atrial activation. Little is known, however, about the effect of pacing from single right atrial sites on differences in interatrial conduction. Twenty-eight patients without structural heart disease were studied following radiofrequency catheter ablation of supraventricular arrhythmias. Pacing was performed using standard multipolar catheters from the presumed insertion site of Bachmann's bundle, the coronary sinus ostium, the high lateral right atrium, and the right atrial appendage (n = 8 patients). Bipolar recording was performed from the distal coronary sinus, the high and low lateral right atrium, and the posterolateral left atrium (n = 13 patients). The longest conduction time from each pacing to each recording site was considered the total atrial activation time for the respective pacing site. During high right atrial pacing, the total atrial activation time was determined by the conduction to the distal coronary sinus (118 +/- 18 ms), during coronary sinus ostium pacing by the conduction to the high right atrium (94 +/- 18 ms), and during Bachmann's bundle pacing by the conduction to the distal coronary sinus (74 +/- 18 ms). The total atrial activation time was significantly shorter during pacing from Bachmann's bundle, as compared to pacing from other right atrial sites. Thus, in normal atria, pacing from the insertion of Bachmann's bundle causes a shorter total atrial activation time and less interatrial conduction delay, as compared to pacing from other right atrial sites. These findings may have implications for alternative pacing sites for prevention of atrial fibrillation.

Analysis of Variance↗
PubMed2001

Inappropriate detection of supraventricular arrhythmias by implantable dual chamber defibrillators: a comparison of four different algorithms.

Inappropriate therapy of supraventricular tachyarrhythmias by an ICD is still a common problem. Dual chamber (DDD) ICDs provide additional atrial sensing and should result in higher specificity for detection of supraventricular tachyarrhythmias. However, a direct comparison of different dual chamber algorithms has not been reported. The detection algorithms of four different DDD ICDs were tested: Phylax AV, Defender IV, Ventak AV III DR, and Gem DR 7271. Based on arrhythmias recorded from patients undergoing invasive electrophysiological studies and in many cases of catheter ablation at our institution, a library consisting of 71 supraventricular and 15 ventricular tachyarrhythmias was created. The library consists of episodes of atrial fibrillation, atrial flutter with different AV conduction, typical and atypical AV nodal reentrant tachycardia, AV reentrant tachycardia, sinus tachycardia, and ventricular tachycardia with and without ventriculoatrial conduction. Atrial fibrillation was appropriately classified by all four algorithms. However, the specificity for detection of other supraventricular tachyarrhythmias achieved by the Biotronik (12%) and the Guidant (11%) devices was significantly lower compared to the specificity of the ELA (28%) and the Medtronic DDD ICD (20%). This is due to the fact that the Biotronik and the Guidant algorithm classified all supraventricular tachyarrhythmias resulting in a stable ventricular rate as ventricular tachycardia, whereas the ELA and Medtronic algorithms performed a more detailed analysis by assessment of PR association, atrial onset, or timing of the atrial event relative to the ventricular event, respectively. Atrial fibrillation, the most common supraventricular tachyarrhythmia in patients with ICD, was detected by all devices.

Algorithms↗
PubMed1998

Pacing in distal left ventricular hypertrophic cardiomyopathy.

We report the case of an 85-year-old woman with distal LV hypertrophy resulting in an intraventricular pressure gradient and incomplete systolic emptying who benefited from permanent DDD pacing. Our experience based on this case suggests that permanent dual chamber pacing might be a safe and effective therapy also in symptomatic patients with the rare form of hypertrophic cardiomyopathy with left mid-ventricular obstruction resulting in incomplete emptying of the apical portion of the LV and a significant intraventricular pressure gradient that was not responding to pharmacological therapy.

Aged↗
PubMed1995

Prediction of atrioventricular block during radiofrequency ablation of the slow pathway of the atrioventricular node.

BACKGROUND: Selective radiofrequency (RF) ablation of the slow pathway is an effective treatment for atrioventricular (AV) nodal reentry tachycardia. A previous report showed that rapid junctional tachycardia (JT) caused by RF associated with loss of ventriculoatrial (VA) conduction is related to increased risk for AV block. However, this can be difficult to detect during energy delivery, and more importantly, it cannot be measured before the onset of RF energy delivery. The aim of our study was to determine whether measurements made from electrograms could be used to predict the risk of AV block before RF energy is delivered. METHODS AND RESULTS: Fifty-eight patients underwent 63 selective slow pathway RF ablation procedures. In 46 (26.9%) of 172 JTs caused by RF, VA block was observed, and in 11 this was followed by AV block of various degrees. Electrograms before each application of RF were analyzed for the interval between the atrial signals in the His bundle catheter and in the distal mapping catheter [A(H)-A(Md)], the interval between the atrial signals in the His bundle catheter and in the proximal coronary sinus catheter [A(H)-A(CS)], the AV ratio, and the presence of a slow pathway potential or a fractionated atrial signal in the distal mapping catheter. Mean cycle length (CL) of JT was calculated if it consisted of at least 10 beats. These parameters were compared between patients with JT who developed VA block and subsequent AV block (group 1), patients with JT and VA block but without subsequent AV block (group 2), and patients with JT without VA block (group 3). The A(H)-A(Md) interval was significantly shorter in group 1 (17 +/- 8 ms) than in groups 2 (33 +/- 8 ms, P < .001) and 3 (32 +/- 10 ms, P < .001), whereas the A(H)-A(Md) intervals of groups 2 and 3 did not differ from each other. CL of JT, A(H)-A(CS) interval, AV ratio, presence of a slow pathway potential, or a fractionated atrial electrogram were not related to the occurrence of AV block. CONCLUSIONS: The A(H)-A(Md) interval provides an electrophysiological marker that can be used in addition to the radiological catheter position to assess the risk for AV block before onset of RF delivery. CL of JT and occurrence of VA block are not related to the risk of AV block.

Atrioventricular Node↗
PubMed1995

[High frequency catheter ablation in AV-nodal reentry tachycardia: clinical significance of slow pathway potentials and junctional tachycardia].

During slow pathway-ablation of AV nodal reentrant tachycardia (AVNRT) with a mean cycle length of 355 +/- 70 ms the clinical significance of slow pathway electrograms (SP-EGM) and junctional tachycardias (JT) was evaluated in 39 patients (9 male, 30 female; mean age 57 +/- 15 years). After two patients were excluded from further investigation because of inadvertent procedural complete heart block, typical SP-EGM were recorded in 30/37 patients (81%) before successful RF administration in the posteroseptal portion of the right atrium. Signals were recorded 61 +/- 22 and 34 +/- 24 ms after atrial activation in the His bundle and proximal coronary sinus catheter, respectively. Additionally, timing was noted 15 +/- 10 ms before the His spike; the duration of SP-EGM was 27 +/- 7 ms, and the A/V relation of the SP-EGM was calculated as 0.59 +/- 0.51 in the ablation bipole. JT was observed in 24/37 patients (78%), with a mean cycle length of 511 +/- 92 ms. The first tachycardia beat appeared initially 4.1 +/- 3.8 s after delivery of the successful RF administration and lasted 18 +/- 8 s. In 14/37 patients (38%) either SP-EGM or JT was missing; in one patient neither of these two was recorded despite successful ablative therapy. The success rate, defined by noninducibility of AVNRT, was 95% (35/37). In 11% (4/37) AVNRT recurred during a mean follow-up of 5 +/- 4 months. In summary, SP-EGM and JT were recorded reproducibly and proved to be a useful tool as electrographic mapping approach of slow pathway ablation in AVNRT.

Adult↗
PubMed1994

Successful radiofrequency ablation of adenosine-sensitive right ventricular outflow tract tachycardia.

We report on a patient without evidence of structural heart disease who presented with adenosine-sensitive sustained ventricular tachycardia with left bundle branch block and right axis QRS morphology. Endocardial catheter mapping revealed the origin of ventricular tachycardia to be located in the right ventricular outflow tract, where the earliest endocardial activation during ventricular tachycardia was registered 30-40 ms prior to onset of QRS complex in the surface ECG. Pace-mapping provided no additional information; we found a good match between 12 lead surface ECGs registered during spontaneous episodes of ventricular tachycardia and those recorded during pacing in a relatively large area in the right ventricular outflow tract. The 10th application of radiofrequency current abolished ventricular tachycardia temporarily, but it recurred within 30 min. After the 28th radiofrequency current delivery ventricular tachycardia was permanently abolished.

Adenosine↗