| 1. |
- Holm, Magnus, et al.
(författare)
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Non-Invasive Assessment of the Atrial Cycle Length during Atrial Fibrillation in Man: Introducing, Validating and Illustrating a New ECG Method
- 1998
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Ingår i: Cardiovascular Research. - 1755-3245. ; 38:1, s. 69-81
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVES: Atrial fibrillation (AF) in man has previously been shown to include a wide variety of atrial activity. Assessment of the characteristics of this arrhythmia with a commonly applicable tool may therefore be important in the choice and evaluation of different therapeutic strategies. As the AF cycle length has been shown to correlate locally with atrial refractoriness and globally with the degree of atrial organization, with, in general, shorter cycle length during apparently random AF compared to more organized AF, we have developed a new method for non-invasive assessment of the AF cycle length using the surface and the esophagus (ESO) ECG. METHODS AND RESULTS: From the frequency spectrum of the residual ECG, created by suppression of the QRST complexes, the dominant atrial cycle length (DACL) was derived. By comparison with multiple intracardiac simultaneously acquired right and left AF cycle lengths in patients with paroxysmal AF, we found that the DACL in lead V1, ranging from 130 to 185 ms, well represented a spatial average of the right AF cycle lengths, whereas the DACL in the ESO ECG, ranging from 140 to 185 ms, reflected both the right and the left AF cycle length, where the influence from each structure depended on the atrial anatomy of the individual, as determined by MRI. In patients with chronic AF, the method was capable of following changes in the AF cycle length due to administration of D,L-sotalol and 5 min of ECG recording was sufficient for the DACL to be reproducible. CONCLUSIONS: We conclude that this new non-invasive method, named 'Frequency Analysis of Fibrillatory ECG' (FAF-ECG), is capable of assessing both the magnitude and the dynamics of the atrial fibrillation cycle length in man.
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| 2. |
- Holm, Magnus, et al.
(författare)
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Non-Invasive Assessment of the Atrial Cycle Length during Chronic Atrial Fibrillation in Man
- 1996
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Ingår i: 69th Scientific Sessions of the American Heart Association, New Orleans, November 10-13, 1996; Circulation, Vol. 94, No. 8 Suppl., pp. I69, 1996.. ; 94, s. 169-169
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Konferensbidrag (refereegranskat)
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| 3. |
- Ingemansson, Max, et al.
(författare)
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Autonomic modulation of the atrial cycle length by the head up tilt test: non-invasive evaluation in patients with chronic atrial fibrillation
- 1998
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Ingår i: Heart. - 1355-6037. ; 80:1, s. 71-76
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: To determine the effects of upright posture compared with supine position on the dominant atrial cycle length (DACL) in patients with chronic atrial fibrillation. DESIGN: The power/frequency spectrum of QRST suppressed lead V1 ECG was studied in 14 patients in the supine position and during the head up tilt table test. The DACL changes were compared with changes in heart rate and blood pressure. RESULTS: Compared with the supine position, the upright position reduced the DACL from 160 to 150 ms (p < 0.01). The DACL was increased after returning to the supine position from the upright position, from 147 to 154 ms (p < 0.01). Heart rate increased from 91 beats/min in the supine position to 106 in the upright position (p < 0.01). There was a decrease in heart rate from 109 beats/min in the upright position to 93 after returning to the supine position (p < 0.01). No significant changes were seen in systolic or diastolic blood pressure. There were indications of an inverse relation between DACL and heart rate when comparing the supine position before and after tilt with the upright position (p < 0.001). CONCLUSIONS: The sympathetic stimulation and vagal withdrawal induced by rising to upright body position are associated with a decrease in DACL during chronic atrial fibrillation. Thus a reflex increase in sympathetic discharge after induction of atrial fibrillation could favour the persistence of the arrhythmia.
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| 4. |
- Ingemansson, Max
(författare)
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Cellular electrophysiological modulation in chronic atrial fibrillation - Studies with magnesium and GIK solution
- 1998
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Although chronic atrial fibrillation (CAF) is the most common sustained cardiac arrhythmia in man, the mechanisms involved in its progressive course are still not fully understood. Recent studies have verified an electrical remodelling of the atrial myocardium that may be responsible for the electrophysiological disturbances known to exist in the fibrillating atria. The electrical remodelling is linked to a defect intracellular calcium handling that seems to involve an increased release of the ion from the sarcoplasmic reticulum. Furthermore, the arrhythmia is associated with a depolarised resting membrane potential of the atrial muscle verified by several authors. Both these mechanisms may at least in part be modulated by magnesium and GIK solution interfering with the intracellular calcium overload and depolarised resting membrane potential, respectively. By investigating the potential effects of magnesium alone and in combination with GIK solution in an animal model and during chronically perpetuated atrial fibrillation in man, several significant effects were obtained. Magnesium prolonged the action potential duration at 90 % repolarisation in guinea pig atrial muscle and increased the atrial refractoriness during CAF. Resting membrane potential was slightly depolarised with higher concentrations of magnesium consistent with an increased intraatrial conduction delay after DC-conversion of CAF. The AV-nodal function during CAF is characterised by dual conduction pathways responsible for the ventricular response. The two AV-nodal conduction pathways were differently affected by magnesium and GIK solution. The autonomic nervous system decreased the atrial refractoriness during CAF, which is in accordance with the proarrhythmic effect of enhanced activity of either limb. These investigations suggest that magnesium in combination with GIK solution may have beneficial electrophysiological effects during CAF.
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| 5. |
- Ingemansson, Max, et al.
(författare)
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Effects of magnesium and glucose, insulin, potassium (GIK) solution on the action potential parameters of guinea-pig atrial muscle
- 1998
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Ingår i: Acta Physiologica Scandinavica. - 0001-6772. ; 164:2, s. 173-179
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Tidskriftsartikel (refereegranskat)abstract
- The present paper aims to explore the effects of [Mg2+]o and glucose, insulin and K+ (GIK) on action potential parameters in guinea-pig atrial muscle. Specimens of atrial appendages were taken from guinea-pig hearts. Action potentials were recorded in isolated atrial trabeculae. Resting potential (RP) and action potential duration at 90% repolarization (APD90) were measured with conventional microelectrode techniques. [Mg2+]o at 6 and 12 mmol L-1 depolarized the RP and prolonged the APD90, whereas 4 mmol L-1 had no effect at all. Glucose alone or in combination with insulin had no effect on action potential parameters. GIK solution with supernormal [K+]o at 6 mmol L-1 depolarized the RP and decreased the APD90. Intervention with [Mg2+]o at 4 mmol L-1 in combination with GIK solution with supernormal [K+]o of 6 mmol L-1, reversibly depolarized the RP, whereas the APD90 was not significantly changed. [Mg2+]o at 12 mmol L-1 in combination with GIK solution with a physiological [K+]o of 4 mmol L-1 prolonged the APD90 whereas the RP was unaffected. [Mg2+]o at 6 and 12 mmol L-1 slightly depolarized the RP and prolonged the APD90. The action potential of normally polarized atrial muscle was not sensitive to supernormal levels of glucose alone or in combination with insulin. The effects of [Mg2+]o in combination with the GIK solutions on action potential parameters seemed to be attributable to the supernormal [Mg2+]o and [K+]o alone, while these seemed to have opposite effects on APD90.
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| 6. |
- Ingemansson, Max, et al.
(författare)
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Effects of MgSO4 and glucose, insulin and potassium (GIK) on atrial conduction during the first 12 hours after DC-conversion of chronic atrial fibrillation
- 2001
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Ingår i: Scandinavian Cardiovascular Journal. - : Informa UK Limited. - 1651-2006 .- 1401-7431. ; 35:5, s. 340-346
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: To investigate changes in atrial conduction induced by MgSO4 and glucose, insulin and potassium (GIK) during the first 12-h period of sinus rhythm after successful DC-conversion of chronic atrial fibrillation (CAF). METHODS: Signal-averaged P-wave duration, QRS-duration and PQ-time were recorded in 20 patients who were randomly assigned to control or intervention. Ten patients received no infusates (control group) and 10 patients received MgSO4 and GIK infusions (intervention group). P-wave duration was determined from the X-, Y- and Z-leads, which were further combined to obtain a spatial magnitude. P-wave morphology was studied by analysing global activation patterns and discrete components from the calculated spatial magnitude signal. RESULTS: No changes in the measured parameters were seen in the control group. The P-wave duration, QRS-duration and PQ-time increased from 139(13) [mean(SD)] to 149(15) (p < 0.01), 90(7) to 94(9) (p < 0.05) and 188(10) to 207(13) ms (p < 0.01). respectively, after bolus infusion of MgSO4. The time from the start of the P-wave to its 1st and 2nd max. locations increased by 6 ms (p < 0.01) in both cases after bolus infusion of MgSO4 and had reversed after 10 h of MgSO4 and GIK infusion. P-wave duration and PQ-time decreased after 10 h of MgSO4 and GIK infusion, from 149(34) (bolus) to 138(12) and from 207(13) to 195(27) ms (p < 0.05), respectively, in spite of an even higher serum Mg concentration at the end of this period. CONCLUSION: Bolus infusion of MgSO4 2 h after DC-conversion of CAF produced an intra-atrial conduction delay that could be reversed by adding a GIK infusion, in spite of a concomitant increase in serum Mg concentration. No recovery of the intra-atrial conduction delay, seen after DC-conversion of CAF, was observed in either of the two groups during the 12-h study period.
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| 7. |
- Ingemansson, Max, et al.
(författare)
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Intravenous MgSO4 alone and in combination with glucose, insulin and potassium (GIK) prolong the atrial cycle length in chronic atrial fibrillation
- 2000
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Ingår i: Europace. - : Oxford University Press (OUP). - 1532-2092 .- 1099-5129. ; 2:2, s. 106-114
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Tidskriftsartikel (refereegranskat)abstract
- AIMS: To investigate the effects of parenteral administration of MgSO4, and glucose, insulin, and potassium (GIK), on the dominant atrial cycle length during chronic atrial fibrillation (CAF). METHODS AND RESULTS: The length of the dominant atrial cycle (DACL) in the power-frequency spectrum of the QRST-suppressed lead V1 ECG was identified before and after intravenous administration of MgSO4 alone and after 5 and 10 h of MgSO4 and GIK infusion, in 13 patients with CAF. The changes in DACL were compared with changes in heart rate (HR), blood pressure and blood parameters. MgSO4 alone increased the DACL from 146(13) (mean(SD)) (control) to 153(14) ms (P < 0.01) and decreased the HR from 102(22) to 95(18) beats x min(-1) (P < 0.05). After 5 h of MgSO4 and GIK infusion the DACL was increased compared with control, from 146(13) to 152(11) ms (P < 0.01), but unchanged compared with that after the bolus infusion of MgSO4. HR was decreased compared with control (102(22)) and the bolus infusion of MgSO4 (95(18)) to 87(15) beats x min(-1) after 5 h of intervention. The DACL was further increased after 10 h of MgSO4 and GIK infusion compared with both control (from 146(13) to 157(11) ms), (P < 0.01) and the 5h infusion (152(11) to 157(11) ms), (P < 0.05). No further changes were seen in HR after 10 h (87(17)) of intervention. There were indications of an inverse relationship between total changes in HR (deltaHR) and DACL (deltaDACL) during the interventions (P < 0.05). CONCLUSION: Bolus infusion of MgSO4 prolongs the DACL and decreases HR in CAF. A further prolongation of DACL was seen after 10 h of MgSO4 and GIK infusion compared with control and with 5 h of intervention. Changes in DACL and HR during the entire intervention period showed an inverse relationship. The antiarrhythmic properties of MgSO4 and the GIK solution in CAF clearly require further attention.
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| 8. |
- Ingemansson, Max, et al.
(författare)
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Modification of intrinsic AV-nodal properties by magnesium in combination with glucose, insulin, and potassium (GIK) during chronic atrial fibrillation
- 1998
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Ingår i: Journal of Electrocardiology. - 1532-8430. ; 31:4, s. 281-292
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: To explore the effects of MgSO4 in combination with glucose, insulin, and potassium (GIK) on intrinsic AV-nodal properties during chronic atrial fibrillation. METHODS: The study included two patient groups--(a) control and intervention and (b) intervention--with different infusion times and concentrations of MgSO4. Ambulatory electrocardiographic recordings were analyzed using modified heart-rate stratified histogram (HRSH) analysis allowing detailed observation of the RR distribution at different average heart rate levels. The two RR-interval populations observed in most patients were characterized by analyzing the relationship between the summits of the peaks of the bimodal histograms. RESULTS: A bimodal RR distribution with a shorter and a longer RR-interval population was observed in 9 of 11 (control), 9 of 11 (intervention) in group (a), and 11 of 13 in group (b) patients. No significant changes in the two RR populations were seen in the control registration (group a). There were, however, indications of a conduction delay in the longer RR intervals in group (a), which received a low concentration of MgSO4, when control was compared with intervention recordings. In group (b), receiving a high MgSO4 concentration, a conduction delay was seen in both the shorter and longer RR populations, being most pronounced for the longer RR population. CONCLUSION: High MgSO4 levels caused a delay in both the shorter and longer RR intervals. The conduction delay in the longer RR population was most pronounced, indicating that MgSO4 differently affected the two corresponding AV-nodal pathways.
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| 9. |
- Meurling, Carl, et al.
(författare)
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Attenuation of electrical remodelling in chronic atrial fibrillation following oral treatment with verapamil
- 1999
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Ingår i: Europace. - : Oxford University Press (OUP). - 1532-2092 .- 1099-5129. ; 1:4, s. 234-241
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Tidskriftsartikel (refereegranskat)abstract
- AIMS: Electrical remodelling with shortening of the atrial refractory period and increased fibrillatory rate occurs after onset of atrial fibrillation and can be attenuated by pre-treatment with intravenous verapamil. The aim of the present study was to investigate whether already established fibrillatory-induced shortening of atrial fibrillatory cycle length could be reversed with oral verapamil. METHODS AND RESULTS: Thirteen patients (nine men; mean age 67 years) with chronic atrial fibrillation (CAF) were studied. The dominant atrial cycle length (DACL) was estimated non-invasively using the frequency analysis of fibrillatory ECG (FAF-ECG) method. Measurements were repeated following treatment with slow release oral verapamil. DACL increased from 147 +/- 13 ms to 156 +/- 21 ms after 1 day (P=0.02), to 164 +/- 18 ms after 5 days (P=0.005) and finally to 160 +/- 16 ms after 6 weeks (P=0.008). CONCLUSION: Long-term oral treatment with verapamil increases the DACL significantly in patients with CAF. The prolongation is evident after 1 day and is further developed during the first 5 days of treatment. Since DACL is believed to be an index of refractoriness, the findings of the present study suggest that this treatment increases the atrial refractory period in patients with CAF.
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| 10. |
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