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| 2. |
- Kongstad Rasmussen, Ole, et al.
(författare)
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Global and local dispersion of ventricular repolarization: endocardial monophasic action potential mapping in swine and humans by using an electro-anatomical mapping system.
- 2002
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Ingår i: Journal of Electrocardiology. - : Elsevier BV. - 1532-8430 .- 0022-0736. ; 35:2, s. 159-167
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Tidskriftsartikel (refereegranskat)abstract
- This article evaluates whether the global dispersion of ventricular repolarization (DVR) can be estimated from measurements between a few adjacent or remote sites. Monophasic action potentials (MAP) were recorded from 61 +/- 18 left (LV) or right ventricular (RV) sites in 10 pigs and 44 +/- 16 LV, or RV sites in 8 patients by using the CARTO mapping system. MAP duration (MAPd) and end-of-repolarization time were calculated at each site and 13 repolarization maps from pigs and 10 from patients were reconstructed. Global dispersions in MAPd and EOR over the LV or RV were compared with the adjacent DVR among 3 - 7 MAPs in areas > or = 0.7 and < or = 1 cm(2) and with the remote DVRs between 2 MAPs with the greatest activation time difference (remote DVR1) and between the apical and laterobasal LV or RV (remote DVR2). The adjacent dispersions in end-of-repolarization and MAPd were significantly smaller than the global ones, 13 +/- 3 and 12 +/- 3 ms vs. 44 +/- 9 and 42 +/- 12 ms in pigs and 13 +/- 7 and 14 +/- 8 ms vs. 72 +/- 24 and 66 +/- 22 ms in patients. The remote DVR1 (30 +/- 8 and 17 +/- 10 ms in pigs and 40 +/- 28 and 28 +/- 17 ms in patients) and remote DVR2 (16 +/- 7 and 11 +/- 10 ms in pigs and 35 +/- 24 and 21 +/- 21 ms in patients) were also significantly smaller than the global DVRs. In conclusion, global DVR is poorly estimated from MAP recordings from a few adjacent or remote sites, suggesting the importance of obtaining global information in evaluating DVR.
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| 3. |
- Roijer, Anders, et al.
(författare)
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Cardiac changes in stroke patients and controls evaluated with transoesophageal echocardiography
- 1997
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Ingår i: Scandinavian Cardiovascular Journal. - : Informa UK Limited. - 1651-2006 .- 1401-7431. ; 31:6, s. 329-337
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Tidskriftsartikel (refereegranskat)abstract
- In stroke patients several cardiac changes associated with embolism can be detected with transoesophageal echocardiography. Potential major cardiac embolic sources (e.g. atrial fibrillation, thrombi of left ventricle/atrium, vegetation, myxoma, dilated cardiomyopathy) have a causal relationship to embolism. Other changes with no certain causal relationship are regarded as potential minor cardiac embolic sources (e.g. atrial septal aneurysm, patent foramen ovale, mitral annular calcification, mitral valve prolapse, protruding atheroma of the aorta). We compared the prevalences of major and minor potential cardiac embolic sources in a stroke population with that in controls. One hundred and twenty-one patients with first-ever stroke were compared with 68 randomly selected controls. All subjects underwent magnetic resonance imaging of the brain, carotid ultrasound and transthoracic/transoesophageal echocardiography. The patients were slightly older (mean age 70.7 +/- 10.3 years) than the controls (65.5 +/- 15.5 years) (p < 0.05). Potential major cardiac embolic sources were found in 27% of the patients and in 4% of the controls (p < 0.001). The most common major potential embolic source was atrial fibrillation, detected in 22/121 patients. Fifteen of these also had spontaneous echocontrast in the left atrium. Eleven left atrial thrombi were found (four of these patients had atrial fibrillation and seven had sinus rhythm). A history of heart disease was more common in patients with a potential major cardiac embolic source or a carotid artery stenosis (77%) than in those patients without (44%) (p < 0.01). After excluding subjects with a major potential cardiac embolic source and/or carotid artery stenosis, no differences in the prevalence of minor potential cardiac embolic sources were found between patients (55%) and control subjects (47%) (p = NS). Even when subjects without a major potential cardiac embolic source or a carotid artery stenosis were categorized into three age groups (35-54, 55-74 and > 74 years) the prevalence of potential minor cardiac embolic sources did not differ between patients and controls. To conclude, major potential cardiac embolic sources are more common in an older population with first-ever stroke than in a comparable control group. However, potential minor cardiac embolic sources did not differ in prevalence in the patients compared with controls. Certain changes (e.g. atrial septal aneurysm) might have a potential embolic role in younger stroke patients but in our study no difference was found between older stroke patients and controls.
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| 4. |
- Yuan, S, et al.
(författare)
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Monophasic action potentials : concepts to practical applications
- 1994
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Ingår i: Cardiovascular Electrophysiology. - : Wiley. - 1045-3873 .- 1540-8167. ; 5:3, s. 287-308
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Tidskriftsartikel (refereegranskat)abstract
- Monophasic Action Potentials. Monophaisc action potential (MAP) recordings reproduce the repolarization time course of intrucellular action potentials with high accuracy and provide precise information on the local activation time. With the advantage of in vivo application and the development of the safer and simpler contact catheter technique, MAP recording has become the method of choice for evaluating myocardial repolarization changes. This review aims to provide information on practical application of MAP recording in the clinical setting. MAPs can easily be recorded from the endocardium with the contact catheter technique in the electrophysiology laboratory and from the epicardium with electrode probes during open heart surgery. The technical aspects are described in detail. The rate dependence of myocardial excitability and repolarization and the effect of antiarrhythmic drugs on MAP duration and effective refractory period are thoroughly reviewed. The use of MAPs in detecting myocardial ischemia, in studying early afterdepolarization and triggered arrhythmias, in measuring dispersion of repolarization, in identifying intracardiac conduction and the development of the T wave, and in verifying the arrhythmogenic effect of mechanoelectric feedback are presented. Computerized automatic analysis of MAPs and the limitations of the MAP technique are also discussed.
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| 5. |
- Platonov, Pyotr, et al.
(författare)
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Permanent atrial fibrillation in patients without structural heart disease is not associated with signs of infection by Chlamydia pneumoniae and Helicobacter pylori.
- 2008
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Ingår i: Acta Cardiologica. - 0001-5385. ; 63:4, s. 479-484
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: The objective of this study was to explore the role of Chlamydia pneumoniae and Helicobacter pylori infections in patients with idiopathic permanent atrial fibrillation. METHODS AND RESULTS: Sera from 72 patients with permanent atrial fibrillation without structural heart disease (mean age 69.6 years, 23 women) were analysed for IgG antibodies against Chlamydia pneumoniae and Helicobacter pylori and compared in a I:I age- and sex-matched case:control manner with those pooled from a healthy reference population of 72 individuals from the same geographical area. After excluding patients with other possible or definite factors known either to cause atrial fibrillation or to affect the prevalence of seropositivity to these agents, the frequency of seropositivity due to one or both of the infectious agents was compared. Serum C-reactive protein (CRP) level was assessed using immunoturbidimetry technique. Both agents were equally common in men and women. Neither seropositivity to Chlamydia pneumoniae (76% vs. 83%, patients vs. control subjests, ns) nor to Helicobacter pylori (57% contra 55%, patients vs. controls, ns) alone reached significance in the comparisons between patients with atrial fibrillation and control subjects. Serum CRP was higher in patients with AF (5.3 mg/L vs. 2.8 mg/L, P < 0.001). CONCLUSIONS: Though presence of permanent AF is associated with elevated CRP levels, this elevation is not the result of earlier infections with Chlamydia pneumoniae or Helicobacter pylori or their combination.
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| 6. |
- Larsson, Jörgen, et al.
(författare)
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Ultrasound enhanced thrombolysis in experimental retinal vein occlusion in the rabbit
- 1998
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Ingår i: British Journal of Ophthalmology. - 1468-2079. ; 82:12, s. 1438-1440
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Tidskriftsartikel (refereegranskat)abstract
- AIMS: To investigate if it was possible to lower the dose of streptokinase and maintain an effective thrombolysis by adding pulsed low energy ultrasound. METHODS: 53 retinal veins in 27 rabbits were occluded by rose bengal enhanced laser treatment. Six rabbits were treated with streptokinase (50,000 IU/kg), 10 rabbits were treated with a low dose of streptokinase (25,000 IU/kg), and 11 rabbits were treated with a low dose of streptokinase (25,000 IU/kg) and pulsed ultrasound during 1 hour. Fluorescein angiography was performed immediately before the thrombolytic treatment and after 12 hours. RESULTS: In the group treated with streptokinase (50,000 IU/kg) all vessels were open. In the group that was given streptokinase (25,000 IU/kg), 21% of the vessels were open. In the group that was treated with streptokinase (25,000 IU/kg) and ultrasound, 64% of the vessels were open. The difference between groups 2 and 3 is statistically significant (p = 0.011) CONCLUSION: Adding pulsed low energy ultrasound makes it possible to lower the dose of streptokinase while maintaining a good thrombolytic effect.
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| 7. |
- Liu, Shaowen, et al.
(författare)
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Atrioventricular conduction: a determinant for the manifestation of ventricular preexcitation in patients with Wolff-Parkinson-White syndrome
- 2001
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Ingår i: Clinical Physiology. - : Wiley. - 1365-2281 .- 0144-5979. ; 21:5, s. 534-540
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Tidskriftsartikel (refereegranskat)abstract
- The relation between the atrioventricular conduction properties of the atrioventricular node and the anterograde conduction ability over the accessory pathway in the Wolff-Parkinson-White syndrome has never been studied. Atrioventricular nodal characteristics were studied in 285 patients with manifest and 204 with concealed accessory pathway who underwent radiofrequency ablation, and compared with 146 controls. First and second degree atrioventricular block was observed in 13 (5%) preexcitation patients after ablation, compared with none in concealed accessory pathway (P=0.001) and control patients (P=0.006). The atrial-His intervals in preexcitation patients (88 +/- 20 ms) was significantly longer than in concealed accessory pathway (76 +/- 15 ms, P<0.0001) and control patients (77 +/- 15 ms, P=0.0007), as was PR intervals (165 +/- 25 versus 149 +/- 20 and 150 +/- 21 ms, P<0.0001, respectively) even after excluding those with atrioventricular block. Significant differences in PR and atrial-His intervals were not observed between concealed accessory pathway and control patients. More preexcitation patients had ventriculoatrial dissociation than had patients in the other groups. The results indicate that atrioventricular block is not uncommon in preexcitation patients and a relatively long atrioventricular conduction time is an electrophysiological prerequisite for the manifestation of preexcitation in the Wolff-Parkinson-White syndrome.
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| 8. |
- Olsson, Bertil
(författare)
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Atrial fibrillation and flutter: aeromedical considerations. New strategies for management and intervention
- 1999
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Ingår i: European Heart Journal Supplements. - 1520-765X. ; 1:Suppl. D, s. 94-97
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Tidskriftsartikel (refereegranskat)abstract
- Few cases of atrial fibrillation can be completely excused from the possibility of having some impact of potential importance in the aviation environment. The clinical pattern in paroxysmal disturbance is very wide and possible incapacitating phenomena are mainly haemodynamic. In contrast, chronic atrial fibrillation is mostly well-tolerated with only minimal haemodynamic effect, but there is a risk of thromboembolism, suggesting the need for anti-thromboembolic treatment. A subgroup with chronic atrial fibrillation with a very low risk may be defined, allowing avoidance of anti-thromboembolic treatment and a positive attitude towards aeromedical certification. Such individuals are likely to be normotensive males, under the age of 60 years, with a normal left (and right) heart configuration on electrocardiography.
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| 9. |
- Yuan, S, et al.
(författare)
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Dispersion of repolarization following double and triple programmed stimulation. A clinical study using the monophasic action potential recording technique
- 1996
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Ingår i: European Heart Journal. - 0195-668X. ; 17, s. 1080-
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Tidskriftsartikel (refereegranskat)abstract
- To study the dispersion of ventricular repolarization following double and triple programmed stimulation and its correlation with the inducibility of ventricular arrhythmias, monophasic action potentials were simultaneously recorded from the right ventricular apex and outflow tract during programmed stimulation in 12 patients with ventricular arrhythmias and a normal QT interval. The time difference between the ends of the two monophasic action potentials were used as a measure of the dispersion of ventricular repolarization, which consists of the activation time difference and the monophasic action potential duration difference. During double and triple programmed stimulation, the dispersion of ventricular repolarization increased significantly with the shortening of the coupling interval but decreased slightly with the shortening of the preceding interval. The induction of the ventricular arrhythmias in these patients was invariably associated with a marked increase in the dispersion of ventricular repolarization. The maximal dispersion of ventricular repolarization was significantly larger in the seven patients with polymorphic ventricular tachycardia and/or ventricular flutter/fibrillation induced than in the four patients with monomorphic ventricular tachycardia induced. Analysis of the two components of the dispersion of ventricular repolarization revealed that the increased dispersion of ventricular repolarization was mainly caused by an increase in the activation time difference in the monomorphic ventricular tachycardia subgroup, and by increases in both the activation time difference and monophasic action potential duration difference in the polymorphic ventricular tachycardia/fibrillation subgroup. These findings suggest that increased dispersion of ventricular repolarization is one of the underlying mechanisms accounting for the myocardial vulnerability to ventricular arrhythmias and that repolarization disturbance is important for the genesis of polymorphic ventricular tachycardia/fibrillation.
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| 10. |
- Carlson, Jonas, et al.
(författare)
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Classification of Electrocardiographic P-wave Morphology
- 2000
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Ingår i: Proceedings of the 39th IEEE Conference on Decision and Control, 2000.. - 0780366387 ; 2, s. 1804-1809
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- The atrial activity of the human heart is normally visible in the ECG as a P-wave. In patients with intermittent atrial fibrilation, a different P-wave morphology can sometimes be seen, indicating atrial conduction defects. The purpose of this study was to develop a method to discriminate between such P-waves and normal ones. 20 recordings of each type were used in a classification which, based on impulse response analysis of the P-wave and linear discrimination between various parameters, produced a correct classification in 37 of the 40 recordings (sensitivity 95%, specificity 90%)
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