69 research outputs found

    Right ventricular performance after valve repair for chronic degenerative mitral regurgitation.

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    Our aim was to assess right ventricular (RV) performance after mitral valve repair by use of RV focused echocardiography and to evaluate the influence of elevated pulmonary artery systolic pressure (PASP) on RV recovery

    Prediction of sinus rhythm maintenance following DC-cardioversion of persistent atrial fibrillation – the role of atrial cycle length

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    BACKGROUND: Atrial electrical remodeling has been shown to influence the outcome the outcome following cardioversion of atrial fibrillation (AF) in experimental studies. The aim of the present study was to find out whether a non-invasively measured atrial fibrillatory cycle length, alone or in combination with other non-invasive parameters, could predict sinus rhythm maintenance after cardioversion of AF. METHODS: Dominant atrial cycle length (DACL), a previously validated non-invasive index of atrial refractoriness, was measured from lead V1 and a unipolar oesophageal lead prior to cardioversion in 37 patients with persistent AF undergoing their first cardioversion. RESULTS: 32 patients were successfully cardioverted to sinus rhythm. The mean DACL in the 22 patients who suffered recurrence of AF within 6 weeks was 152 ± 15 ms (V1) and 147 ± 14 ms (oesophagus) compared to 155 ± 17 ms (V1) and 151 ± 18 ms (oesophagus) in those maintaining sinus rhythm (NS). Left atrial diameter was 48 ± 4 mm and 44 ± 7 mm respectively (NS). The optimal parameter predicting maintenance of sinus rhythm after 6 weeks appeared to be the ratio of the lowest dominant atrial cycle length (oesophageal lead or V1) to left atrial diameter. This ratio was significantly higher in patients remaining in sinus rhythm (3.4 ± 0.6 vs. 3.1 ± 0.4 ms/mm respectively, p = 0.04). CONCLUSION: In this study neither an index of atrial refractory period nor left atrial diameter alone were predictors of AF recurrence within the 6 weeks of follow-up. The ratio of the two (combining electrophysiological and anatomical measurements) only slightly improve the identification of patients at high risk of recurrence of persistent AF. Consequently, other ways to asses electrical remodeling and / or other variables besides electrical remodeling are involved in determining the outcome following cardioversion

    Age-related changes in P wave morphology in healthy subjects

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    <p>Abstract</p> <p>Background</p> <p>We have previously documented significant differences in orthogonal P wave morphology between patients with and without paroxysmal atrial fibrillation (PAF). However, there exists little data concerning normal P wave morphology. This study was aimed at exploring orthogonal P wave morphology and its variations in healthy subjects.</p> <p>Methods</p> <p>120 healthy volunteers were included, evenly distributed in decades from 20–80 years of age; 60 men (age 50+/-17) and 60 women (50+/-16). Six-minute long 12-lead ECG registrations were acquired and transformed into orthogonal leads. Using a previously described P wave triggered P wave signal averaging method we were able to compare similarities and differences in P wave morphologies.</p> <p>Results</p> <p>Orthogonal P wave morphology in healthy individuals was predominately positive in Leads X and Y. In Lead Z, one third had negative morphology and two-thirds a biphasic one with a transition from negative to positive. The latter P wave morphology type was significantly more common after the age of 50 (P < 0.01). P wave duration (PWD) increased with age being slightly longer in subjects older than 50 (121+/-13 ms vs. 128+/-12 ms, P < 0.005). Minimal intraindividual variation of P wave morphology was observed.</p> <p>Conclusion</p> <p>Changes of signal averaged orthogonal P wave morphology (biphasic signal in Lead Z), earlier reported in PAF patients, are common in healthy subjects and appear predominantly after the age of 50. Subtle age-related prolongation of PWD is unlikely to be sufficient as a sole explanation of this finding that is thought to represent interatrial conduction disturbances. To serve as future reference, P wave morphology parameters of the healthy subjects are provided.</p

    Atrial Fibrillation. Modulation of the atrial fibrillatory frequency. A non-invasive approach.

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    Aim: To non-invasively detect and explore the changes in atrial fibrillatory cycle length (i.e. changes in the atrial refractory period) in humans with chronic atrial fibrillation (CAF) following autonomic modulation and pharmacological intervention. Furthermore we investigated if the value of the atrial fibrillatory cycle length could predict outcome following DC-cardioversion. Methods: The study enrolled patients with persistent or permanent AF. Data was acquired using 12-lead standard ECG equipment, a unipolar oesophageal lead or digital Holter recorders. Assessment of atrial fibrillatory electrophysiology was made non-invasively with power spectrum frequency analysis of QRST cancelled ECG using the frequency analysis of fibrillatory ECG methodology (FAF-ECG). The peak frequency was converted to a cycle length, termed dominant atrial cycle length (DACL), which is a validated index of atrial refractoriness. Results: In the first study (I) the DACL derived from both surface and oesophageal ECG as well as additional parameters of the FAF-ECG methodology were evaluated in clinical practice. The second study (II) showed that oral treatment with verapamil increases DACL (and therefore by inference atrial refractory period) in patients with chronic AF. The two following studies (III, IV) investigated the effects of autonomic modulation on atrial fibrillatory electrophysiology. The first of these (III), demonstrated that adrenergic stimulation decreases the DACL and that vagal withdrawal initially increases the DACL. The other study (IV) found that atrial fibrillatory cycle length shows significant diurnal variation, with shorter cycle lengths during day and consequently longer cycle lengths during night. Finally, we demonstrated that the ratio of DACL and left atrial diameter is higher in patients maintaining in sinus rhythm after DC-cardioversion of persistent AF (V). Conclusion: The FAF-ECG method can estimate DACL in the majority of patients, allowing non-invasive assessment of atrial refractoriness and of spatial dispersion in DACL, power maximum and spectral width of DACL (I). Since DACL is recognised as an index of refractoriness, we have demonstrated that already established electrical remodelling can be attenuated/partly reversed with calcium channel blockade (II). Changes in the electrophysiological properties of the fibrillating atrium during pharmacological autonomic modulation are detectable by the FAF-ECG method, and sympathetic modulations appear to be more pronounced than vagal ones during chronic AF (III). DACL, and hence atrial refractoriness, exhibits significant diurnal fluctuations during chronic AF, with a shorter mean DACL during daytime (IV). Prediction of sinus rhythm maintenance following cardioversion is optimised by combining electrophysiological and anatomical measurements, but the absolute predictive accuracy is modest, suggesting other etiological factors than absolute degree of electrical remodelling are important (V)

    Characterization of atrial fibrillation using the surface ECG: time-dependent spectral properties

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    Time-frequency analysis is considered for characterizing atrial fibrillation in the surface electrocardiogram (ECG). Variations in fundamental frequency of the fibrillatory waves are tracked by using different time-frequency distributions which are appropriate to short- and long-term variations. The cross Wigner-Ville distribution is found to be particularly useful for short-term analysis due to its ability to handle poor signal-to-noise ratios. In patients with chronic atrial fibrillation, substantial short-term variations exist in fibrillation frequency and variations up to 2.5 Hz can be observed within a few seconds. Although time-frequency analysis is performed independently in each lead, short-term variations in fibrillation frequency often exhibit a similar pattern in the leads V1, V2 and V3. Using different techniques for short- and long-term analysis, it is possible to reliably detect subtle long-term changes in fibrillation frequency, e.g., related to an intervention, which otherwise would have been obscured by spontaneous variations in fibrillation frequency

    Detection of autonomic modulation in permanent atrial fibrillation

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    A new signal processing method for the detection of cyclic variations in atrial fibrillation frequency is presented. The objective was to investigate whether or not respiration, through the autonomic nervous system, modulates the fibrillation frequency in patients with permanent atrial fibrillation. A group of eight patients with permanent atrial fibrillation, atrioventricular block III and a permanent pacemaker were studied during rest, rhythm-controlled respiration, with each breath lasting for 8 s (i.e. a breathing frequency of 0.125 Hz), and rhythm-controlled respiration after full vagal blockade by atropine. Using the new method, a spectral peak could be detected, in two of the patients, at the breathing frequency during rhythm-controlled respiration then disappeared after injection of atropine
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