Dual atrioventricular nodal non-re-entrant tachycardia (DAVNNT), also known as 'double fire', has recently received more attention since it was demonstrated to mimic more common arrhythmias such as atrial premature beats, atrial fibrillation, and ventricular tachycardia. This is important, since mistaken differential diagnoses and the resulting therapeutic decisions have severe consequences for affected patients. DAVNNT is characterized by conduction characteristics of the atrioventricular (AV) node that leads to a double antegrade conduction of one sinoatrial nodal activity via the slow and fast AV nodal pathways. As a result, the most significant hint from an electrocardiogram (ECG) is a P wave followed by two narrow QRS complexes. Although DAVNNT is rather a rare arrhythmia, it now appears to be more common than previously thought. To date, 68 cases including 3 small single-centre observational studies accumulated over the last 5 years have demonstrated the feasibility and safety of radiofrequency catheter ablation for DAVNNT. Catheter ablation treats this arrhythmia effectively by modifying or eliminating slow pathway function. Here, we review the current state of DAVNNT knowledge systematically and address current challenges presented by this 'ECG chameleon from the AV node'.
The DAVNNT seems to be more common than previously thought. This important differential diagnosis needs to be taken into consideration as slow pathway modulation can be curative while a misdiagnosis, such as atrial fibrillation or ventricular tachycardia might result in over-treatment in patients with this arrhythmia.
Pulse detection via palpation is a basic and essential procedure in daily medical practice. We have been investigating the performance of a single accelerometer placed above the carotid artery, which is one of the recommended locations for manual palpation. A low-cost sensor attached by an adhesive measures accelerations due to carotid dilatations and whole body vibrations. A real-time demonstrator has been developed to classify 10 second- windows in "Pulse", "Motion" and "No Pulse" and to infer pulse rate. Data were obtained during a scheduled head-up tilt table test (HUTT). Our results show for a subgroup of 10 patients with acute hypotension a wide spread of "good" signal coverage ranging from as low as 37% up to 100%. Key factors compromising the performance in HUTT are motion artifacts, arrhythmias, sensor placement and sensor-skin coupling. In conclusion, pulse detection with a single accelerometer is sufficiently accurate, if good signal coverage can be achieved.
Hintergrund Vorhofflimmern (VHF) ist aktuell in Deutschland die vierthäufigste Ursache einer Hospitalisierung. Trotz enormer
Background: Magnetocardiographic mapping (MCG) provides real-time imaging of the magnetic field (MF) produced by cardiac ionic currents. Compared to the electrocardiogram (ECG), MCG is more sensitive to tangential currents and detects also vortex currents unrecordable by ECG. Such additional information may explain why MCG may detects ventricular repolarization (VR) abnormality suggestive of ischemia earlier than ECG and enzyme pattern. So far, high costs and complexity of cryogenic instrumentation working in magnetically shielded rooms have impeded widespread clinical application of MCG in hospital environments. However, with the development of new non-cryogenic sensors a wider use of MCG in unshielded hospital environments is foreseen, especially to rule-out ischemic heart disease (IHD) in patients presenting with chest pain in emergency departments. Purpose: The aims of this study were to validate the feasibility of MCG carried out in an unshielded hospital ambulatory room and to estimate the repeatability and reproducibility of VR parameters currently used for the diagnosis of IHD. Results: A database of MCG measurements in healthy subjects was obtained, useful to define the normal range of each parameter in a larger cohort compared to previous studies. The average CV ± SEM of all MCG parameter for the entire cohort were 16.2±1.4 (%) and good individual repeatability was found for each MCG parameter at Bland Altman analysis. The reproducibility was optimal (ICC >0,7) for 11 out of 12 parameters (mean values). When evaluated individually, the reproducibility was optimal for 8 and good (>0.6) for 3 out of the 12 parameters. Conclusion: Reliable MCG recordings can be obtained into an unshielded hospital room, with a good repeatability and reproducibility of the most VR parameters. The range of normality obtained in the present study was substantially in agreement with previous preliminary observations on smaller population. No significant gender-related difference of VR parameters was observed. Both repeatability and reproducibility of MCG VR parameters were more than adequate for clinical use, except for the MF Extrema "Distance Dynamics", which deserves further evaluation. P5518 | BEDSIDEReduced heart rate response after premature ventricular contraction in mildly symptomatic patients with atrial fibrillation: analysis on heart rate turbulence Background: The severity of symptoms during atrial fibrillation (AF) may be influenced by heart rate and blood pressure variation, due to irregular beats and the related adaptations in baroreflex sensitivity. Heart rate turbulence (HRT) is considered to be a baroreflex related heart rate reaction in response to premature beats. Purpose: The aim of this study was to assess the relationship between the HRT reflecting a baroreflex sensitivity and the intensity of symptoms during AF. Method: Patient population consisted of 97 patients (pts) who underwent electrophysiological study. Consecutive fifty-six pts had paroxysmal AF (21 with milder symptoms [EHRA class I or II; Gro...
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